Methods and apparatus employed to locate body vessels and occlusions in body vessels finding particular utility in cardiac surgery, particularly minimally invasive cardiac surgery to locate cardiac arteries and occlusions in cardiac arteries are disclosed. An elongated vessel lumen probe incorporating a lumen probe element at or near the elongated vessel lumen probe distal end is advanced into the vessel lumen. A vessel surface probe manipulated by the surgeon and having a surface probe element sensor is employed to detect the lumen probe element and to follow the progress of the vessel lumen probe element as it approaches and is advanced through or is blocked by an occlusion. In the location of a coronary artery, the surface probe element sensor is moved about against the epicardium over the suspected location of the artery of interest until a surface probe element sensor of the present invention at the surface probe distal end interacts with the lumen probe element of the vessel lumen probe.

Diseases of the cardiovascular system affect millions of people each year and are a leading cause of death throughout the world. The cost to society from such diseases is enormous both in terms of the number of lives lost as well as in terms of the costs associated with treating patients through traditional surgical techniques. A particularly prevalent form of cardiovascular disease is coronary artery disease (CAD), which is caused by atherosclerosis. Atherosclerosis is a disease in which the lumen (interior passage) of an artery becomes stenosed (narrowed) or even totally occluded (blocked) by an accumulation of fibrous, fatty, or calcified tissue (hereinafter referred to collectively for convenience as an occlusion). Over time, this tissue, known in medicine as an atheroma, hardens and occludes the artery. The partial stenosis or full occlusion of the coronary arteries that supply the heart muscle leads to ischemia (deficient blood flow) of the heart muscle, angina (chest pain), and can lead to infarction (heart attack) or patient death. Although drug therapies and modifications to diet and lifestyle show great promise for preventing and treating atherosclerotic vascular disease, many patients urgently require restoration of blood flow that has already been lost, especially in those having severely or totally occluded blood vessels.
In many cases, a patient suffering such a coronary vessel occlusion undergoes a coronary artery bypass graft (CABG) surgical procedure, more commonly known as a "heart bypass" operation to restore normal oxygenated blood flow to the heart muscle downstream of the occlusion. The heart bypass typically involves surgically attaching a blood vessel harvested from the patient's body from a source of oxygenated blood, e.g., the aorta or a site of the obstructed coronary artery proximal to the obstruction, to provide a conduit for oxygenated blood downstream or distal to the occlusion to restore the flow of oxygenated blood to the heart muscle. CABG surgery is generally lengthy, traumatic and subject to patient risk. Among the risk factors involved is the use of a cardiopulmonary bypass (CPB) circuit, also known as a "heart-lung machine", to both pump blood and oxygenate the blood so that the patient's heart can be stopped or arrested during the surgery, with its function performed by the CPB circuit. Recently, beating heart procedures have been developed that eliminate the need for any form of CPB.
In one approach, the surgeon harvests a section of a blood vessel from the patient's venous or arterial system, closes any branching vessel openings, and prepares its proximal and distal ends to be attached in a "proximal anastomosis" and a "distal anastomosis" bypassing the occlusion. The proximal or inflow end of such a "free graft" can be attached via a proximal anastomosis at a site proximal or upstream to the occlusion or to another vessel supplying oxygenated blood, e.g., the aorta. Generally, a free graft is a section of the saphenous vein harvested from the patient's leg or segment of radial artery harvested from the patient's arm.
In another approach, an available blood vessel within the trunk is dissected from supporting tissue while leaving it connected to the source of oxygenated blood so as to provide a source vessel free end. The sites of excision of the "attached" graft are closed to avoid blood loss, and the source vessel free end is anastomosed to the obstructed coronary artery at a distal anastomosis site distally or downstream from the occlusion that obstructs or restricts blood flow.
The trunk hosts a number of potential grafts including, the left internal mammary artery (left IMA), the right internal mammary artery (right IMA), the radial arteries and three visceral arteries, one in the abdomen, and two in the lower abdominal wall, though the latter can be quite short and are generally of limited usefulness. The visceral arteries include the epigastric artery, the gastroepiploic artery and the splenic artery.
The left IMA is best used for bypass to the left anterior descending (LAD) coronary artery and its diagonal branches, whereas, the right IMA can be used for bypass to selected vessels more posterior such as the distal right coronary artery (RCA). The right IMA can also be used for bypass to selected marginal branches of the left circumflex coronary artery. A segment of radial artery harvested from an arm is generally used to revascularize the posterior surface of the heart. The right gastroepiploic artery can be used to revascularize almost any artery on the surface of the heart and is most commonly used for bypass to the distal RCA or the posterior descending coronary artery. In unusual circumstances, the splenic artery is used to revascularize posterior coronary arteries, but it is long enough to reach the marginal branches of the circumflex coronary artery.
Surgeons typically complete bypass grafts to the following coronary arteries in a patient undergoing multiple bypass surgery in roughly the following order: posterior descending coronary artery (PDA), RCA, obtuse marginal branch, circumflex coronary artery, diagonal branch, and LAD. More generally, surgeons typically revascularize the three coronary systems in the following order: right, circumflex, and anterior descending. However, the order can vary depending on whether the procedure is performed on a beating heart or an arrested heart. About three to four bypass grafts, of which one to three are free grafts, are generally performed per procedure when the heart is arrested. In contrast, about two to three bypass grafts, of which zero to two are free grafts, are generally performed per beating heart procedure. In general, one free graft is used per beating heart procedure.
Two anastomoses are performed when a saphenous vein or other blood vessel is used as a free graft in a CABG procedure; one to the diseased artery distal to the obstruction (outflow end) and one proximally to the blood vessel supplying the oxygenated blood (inflow end). End-to-side anastomotic techniques described further herein are usually performed, although end-to-end or side-to-side anastomotic techniques described further herein are performed at times. For example, sequential graft techniques or "jump" grafts which use side-to-side anastomoses can be used to conserve the amount of blood vessels required when more than one graft is required in any of the three coronary systems for complete revascularization of the heart.
The majority of surgeons will complete the distal anastomosis of a free graft prior to completion of the proximal anastomosis. The small percentage of surgeons who do complete the proximal anastomosis first usually do so to allow antegrade perfusion of cardioplegic solution through the graft during revascularization.
Construction of an anastomosis begins by first precisely locating the occlusion within the target coronary artery. Then, the anastomosis site(s) of the target coronary artery are isolated from the epicardial tissues and overlying fatty layers. Typically, blunt, rounded #15 scalpel blades are employed to dissect these tissues and layers away from the target coronary artery. Blood flow in the target coronary artery can be interrupted by, for example, temporary ligation or clamping of the artery proximal and distal of the anastomosis site. The target coronary artery wall is opened to form an arteriotomy, that is, an elongated incision at the anastomosis site extending parallel to the axis of the coronary vessel and equally spaced from the sides of the coronary artery that are still embedded in or against the epicardium. The arteriotomy is typically created by use of a very sharp, pointed, #11 scalpel blade to perforate the target coronary artery wall, and the puncture is elongated the requisite length using scissors. The length of the incision generally approximates the diameter of the graft or source vessel, e.g., a typical incision for a saphenous vein is about 4 to 5 mm. A "perfect arteriotomy" is an incision that has straight edges, that does not stray from the axial alignment and equal distance from the sides of the coronary artery, and is of the requisite length. A variety of techniques and devices may be used to form an arteriotomy and/or aortotomy, i.e., an incision in the aorta. For example, devices that can cut tissue may be used to form an incision in a vessel. Devices that can cut tissue include mechanical devices, e.g., scissors, scalpel, knife or punch, radio frequency (RF) devices, e.g., electrocautery devices, laser devices and ultrasound devices.
Next, it is necessary to prepare the attachment end or ends of the graft or source vessel by cutting the source vessel end to an appropriate angle for an end-to-side anastomosis or by closing the source vessel end and forming an elongated arteriotomy in the source vessel wall of a suitable length that is axially aligned with the source vessel axis for a side-to-side anastomosis. In an end-to-side anastomosis, it is necessary to prepare the attachment end of the source vessel by beveling its severed end typically at about 30 to 45 degrees. Generally, the surgeon uses surgical scalpels and scissors to shape the source vessel end or make the elongated arteriotomy slit in the source vessel, and sutures to close the open severed end. One method of forming an elongated arteriotomy of a suitable length axially aligned with the source vessel axis for a side-to-side anastomosis is shown, for example, in U.S. Pat. No. 5,893,369.
The prepared end or elongated arteriotomy slit of the bypass graft or source vessel is attached or anastomosed to the target coronary artery at the arteriotomy in a manner that prevents leakage of blood. The inner, endothelial layer, vessel linings are less thrombogenic than the outer epithelial layers. So, in one approach, the attachment of graft to target artery is made by everting and applying the interior linings of the bypass graft or source vessel and the target coronary artery against one another and suturing the everted linings together. Surgeons can construct the anastomosis via a ten-stitch running suture using 7-0 polypropylene suture material. The ten-stitch anastomosis typically comprises five stitches around the "heel" of the source vessel and five stitches around the "toe" of the source vessel. The five stitches around the heel of the graft comprise two stitches to one side of the apex of the graft and the artery, a stitch through the apex and two stitches placed at the opposite side of the apex. The graft is generally held apart from the coronary artery while the stitches are constructed using a needle manipulated by a forceps. Suture loops are drawn up and the suture pulled straight through to eliminate purse-string effect. The five stitches around the toe of the graft also comprise two stitches to one side of the apex of the graft and the artery, a stitch through the apex and two stitches placed at the opposite side of the apex. Again, suture loops are drawn up, the suture is pulled straight through to eliminate purse-string effect, and the suture ends are tied.
The proximal anastomosis of a saphenous vein free graft to the aorta, i.e., an aortosaphenous vein anastomosis, is formed by first removing the pericardial layer that covers the aorta. An occluding or side-biting clamp can be placed on the aorta at the anastomosis site. A small circular or elliptical portion of the ascending aorta is excised forming a small opening, or aortotomy, 4 to 5 mm in diameter. An aortic punch typically facilitates this procedure. The opening for a right-sided free graft is made anterior or to the right lateral side of the aorta, whereas an opening for a left-sided free graft is made to the left lateral side of the aorta. The opening is made proximal on the aorta if the free graft is to supply blood to the right coronary artery. If the free graft is to supply blood to the anterior descending coronary artery, the opening is made in the middle on the aorta. And, if the free graft is to supply blood to the circumflex artery, the opening is made distal on the aorta. The right graft opening is placed slightly in the right of the anterior midpoint of the aorta and the left graft opening slightly to the left. The end of the saphenous vein free graft is cut back longitudinally for a distance of approximately 1 cm. A vascular clamp is placed across the tip of the saphenous vein free graph to flatten it, thereby exposing the apex of the vein. Five suture loops of a running suture using 5-0 polypropylene are then placed around the heel of the saphenous vein free graft and passed through the aortic wall. Two stitches are placed on one side of the apex, the third stitch is placed precisely through the apex of the incision in the saphenous vein free graft, and the final two stitches are placed on the opposite side of the apex. Suture traction is used to help expose the edge of the aortic opening to ensure accurate needle placement. Stitches include about 3 to 5 mm of the aortic wall for adequate strength. Suture loops are then pulled up to approximate the vein graft to the aorta. The remaining stitches are placed in a cartwheel fashion around the aortic opening thereby completing the remainder of the anastomosis.
Left-sided grafts are oriented so the apex of the incision in the heel of the saphenous vein free graft will face directly to the left side. The stitches are placed in a clockwise fashion around the heel of the graft and in a counterclockwise fashion around the aortic opening. Right-sided grafts are oriented in a caudal fashion. The stitches are placed in a counterclockwise fashion around the heel of the graft and in a clockwise fashion around the aortic opening. Five suture loops complete the heel portion of the graft and an additional five or six are necessary to complete the toe of the graft. Finished proximal anastomoses tend to have a "cobra-head" appearance.
It is essential for the surgeon to take steps to minimize the possibility of thrombosis, narrowing and/or premature closure of the anastomosis due to technical errors. Some surgeons feel the proximal anastomosis must have a take-off angle of 45 degrees while other surgeons believe the take-off angle is not critical. In addition, it was felt that intima-to-intima contact of the vessels at the anastomosis was critical for endothelization to occur, thereby making an ideal union of the vessels. However, most surgeons now feel intima-to-adventitia contact is acceptable. The main objective of the surgeon is to create an anastomosis with an expected long-term patency rate of greater than 5 to 10 years. The creation of an anastomosis takes approximately 10-15 minutes.
Adequate exposure that affords acute visualization of the vessel walls is an essential requirement for creating a sutured anastomosis without error. Acute visualization of the vessel walls is mandatory in order to properly place each stitch and avoid inadvertently including the back wall of the vessel in a stitch, which in effect narrows or completely occludes the vessel. Most surgeons employ blood-less field devices such as shunts, snares, and misted blowers to achieve the required exposure.
Currently, manual suturing is the gold standard for creation of a vascular anastomosis. However, a number of cardiac surgical procedures, e.g., off-pump, beating heart CABG procedures, minimally invasive procedures and even totally endoscopic procedures with access through ports only, can require a variety of other anastomotic techniques. Avoiding the use of cross clamps and CPB or dramatically reducing pump run and cross clamp times can effectively minimize post-operative complications. For this reason, surgeons have been increasingly using easier, quicker, less damaging, but reliable automated, semi-automated, or at least facilitated methods to replace or enhance the normal process of a manually sutured vascular anastomosis.
The major objective of any CABG procedure is to perform a technically perfect anastomosis. However, creation of a technically perfect anastomosis is generally complex, tedious, time consuming and its success is highly dependent on a surgeon's skill level. Therefore, it is perceived that creation of vascular anastomoses without the need to perform delicate and intricate suture lines may enable surgeons to more quickly create simpler and effective anastomoses. Currently, a number of mechanical anastomotic devices, materials, techniques, and procedures are being developed for facilitating the process of forming an anastomosis including vascular clips or staplers, glues, adhesives or sealants, laser welding, mechanical couplers, stents and robot-assisted suturing. These techniques are being developed for performing end-to-end, end-to-side and/or side-to-side anastomoses with or without temporary blood flow interruption. In general, these techniques can include the use of various biomaterials and/or biocompatible agents. See, for example, U.S. Pat. Nos. 5,385,606, 5,695,504, 5,707,380, 5,972,017 and 5,976,178, and 6,231,565.
Sealants, adhesives or glues used in creation of vascular anastomoses are generally based on synthetic or biological substances or a combination of both that are used to either seal post-operative internal air or fluid leaks, or to close a topical wound. Surgical sealants are generally absorbable materials used primarily to control internal bleeding and to seal tissue. Surgical adhesives are stronger than sealants, are often non-absorbable, and typically are biologically based. Surgical glues are stronger than surgical adhesives, are often synthetic and non-absorbable, and are often used to close topical wounds. Surgical glues are typically made from cyanoacrylate adhesives that form strong tissue-to-tissue bonds and are used to bond a wide variety of materials. Biologically based sealants, adhesives or glues are generally derived from blood clotting components such as proteins (e.g., fibrinogen or fibrin), enzymes (e.g., thrombin) and/or platelets. Fibrin based sealants, adhesives or glues generally combine the protein fibrinogen with the enzyme thrombin to immediately begin the clotting process. One surgical adhesive currently being marketed includes a combination of collagen (proteins which form fibers to support body tissues), formalin (a form of formaldehyde), resorcinol and glutaraldehyde. Some sealants, adhesives or glues can be used to control bleeding or to reinforce suture or staple lines rather than to make tissues adhere, thus functioning more as hemostatic agents than glues.
There are a number of uses for sealants, adhesives or glues, such as replacement for sutures and staples in minimally invasive procedures, where the surgeon has little room to maneuver, or for the repair of aortic dissections, where the tissue is so thin it can be damaged by sutures. Such sealants, adhesives or glues can also be used for anastomotic sealing, in which the seal should not be absorbed, or carotid patching, where a complete seal is desired.
Laser welding techniques using laser energy emitted by CO2 lasers, argon lasers or Neodymium-YAG lasers, for example, which thermally join tissues together can also be used to create the anastomosis between the source vessel and coronary artery tissues. One possible mechanism of laser welding of tissues is the thermal denaturation and coagulation of collagen fibrils in the tissue, which generally occur above 60° C. Photosensitive dyes (e.g., indocyanine green) that absorb the laser energy can be applied to the tissues to be joined at the weld site to enhance the weld strength while minimizing thermal damage to the surrounding tissue. Photosensitive dyes used in laser welding procedures may or may not bind chemically to the tissue's proteins depending on their chemical structure. Laser welding can provide a watertight seal to hold bodily fluids in, thereby preventing blood loss, infections and repeat surgeries. Alternatively, a "solder" comprising synthetic and/or biological components that absorb the laser energy can be applied to the tissues to be joined at the weld site to enhance the weld strength while minimizing thermal damage to the surrounding tissue. For example, proteins such as albumin have been used in various solder formulations. Laser welding devices can include one or more flexible optical fibers and solder-delivery tubes that can be snaked through small ports or through a channel in an endoscope.
Mechanical anastomotic devices include stapling devices, clipping devices, ring and pin coupling devices, and suturing devices. These anastomotic devices can be automated or semi-automated. Mechanical anastomotic devices also include mechanical couplers including stents, ferrules, and/or rings. Materials used to form an anastomosis via a mechanical device and/or coupler must be biocompatible, bio-absorbable, bio-active and/or bio-inert.
One component intra-luminal mechanical coupling devices are generally stent-like in design. The graft and the target vessel, i.e., the aorta or coronary artery, are forced into tubular shapes by the device. In general, the application of this type of device is relatively easy. The device can be made to unfold by itself so no deformation forces are necessary at the anastomosis. In addition, angled anastomoses are possible. The device can however have a lot of foreign material exposed within the blood stream, thus increasing the risk of stenosis and thrombosis. In some cases, the device can prevent direct contact between the graft and the target vessel, thereby preventing the vessel walls from healing together. Intimal damage to both the graft and the target vessel can also occur during delivery of the device. Extra sealing methods, e.g., tissue sealants, may be necessary to provide a leak-free anastomosis. In addition, the size of the device is strongly related to the size of the vessels. Therefore, a range of devices and measurement of the vessels is necessary.
Two component intra-luminal mechanical coupling devices require both the graft and the target vessel to be connected to their own coupling component, after which the two coupling components are connected to each other, thereby forming the complete anastomosis. Problems associated with construction of an anastomosis using a two component intra-luminal mechanical coupling device can include mounting of the vessels and connection of the components. Tools for mounting the individual coupling components to each vessel and tools for connecting the coupling components together are both generally required.
One component, extra-luminal, mechanical coupling devices typically allow direct intima-to-intima contact and typically require a delivery tool to position the coupling device in the recipient vessel. In addition, this type of device present less foreign material in the blood stream, thereby decreasing the risk of stenosis and thrombosis. However, mounting of the graft to the coupling device may not be easy. Damage can occur to the intimal layer when everting the graft onto the device for two reasons: 1) one tip of a pair of pincers used to solidly grab vessel wall to evert an artery will roughly touch and pinch the intima of the artery; and, 2) eversion causes high strain (stretching) that can damage the arterial wall. A high level of surgical skill and experience is necessary to reduce the probability that such damage occurs. The skilled surgeon must estimate where to grab the vessel wall and how to evert the graft onto the device to obtain a symmetrical anastomosis. A specially designed mounting tool can make the step of mounting the graft onto the coupling device easier and can help to minimize damage to the graft. In addition, care must be taken to avoid compression of tissue by the coupling device since compression can cause pressure necrosis.
Two component extra-luminal mechanical coupling devices, like the two component intra-luminal mechanical coupling devices, require both the graft and the target vessel to be connected to their own coupling component, after which the two coupling components are connected to each other, thereby forming the complete anastomosis. Problems associated with construction of an anastomosis using a two component extra-luminal mechanical coupling device also include mounting of the vessels and connection of the components. Tools for mounting the individual coupling components to each vessel and tools for connecting the coupling components together are both generally required. Hybrid anastomosis techniques combine one or more techniques, e.g., sutures or clips with glues or laser welding. A specific example of a hybrid anastomotic technique is the use of an intraluminal stent-like device combined with an extraluminal application of biological glue.
Various types of artificial biocompatible reinforcement sleeves or rings, e.g., those shown in the above-referenced '369 patent can be used in the anastomosis. Other examples of forming the arteriotomy, the shaped end or side wall of the source vessel, and the positioning and attachment of the source vessel and target artery together are set forth in U.S. Pat. Nos. 5,799,661, 5,868,770, 6,026,814, 6,071,295, 6,248,117, and 6,332,468.
Largely invasive surgical techniques are typically employed to provide the surgeon access to the anastomoses sites. For this reason, CABG surgery is generally performed through a median sternotomy (open-chest surgical exposure). A median sternotomy incision begins just below the sternal notch and extends slightly below the xyphoid process. A sternal retractor is used to separate the sternal edges for optimal exposure of the heart. Hemostasis of the sternal edges is typically obtained using electrocautery with a ball-tip electrode and a thin layer of bone wax.
Typically, fat layers that make it difficult to see either the artery or the occlusion cover the epicardial surface and the obstructed cardiac artery. However, surgeons are able to dissect the fat away to expose the artery and manually palpate the heart to feel the relatively stiff or rigid occlusion within the artery as a result of their training and experience. The surgeon can determine the location and length of the occlusion as well as suitable sites of the target coronary artery for the proximal and distal anastomoses with some degree of success. However, it is difficult to accurately determine the bounds of a soft or "cheesy" occlusion, and mistakes can happen.
The open chest procedure involves making a 20 to 25 cm incision in the chest of the patient, severing the sternum and cutting and peeling back various layers of tissue in order to give access to the heart and arterial sources. As a result, these operations typically require large numbers of sutures or staples to close the incision and 5 to 10 wire hooks to keep the severed sternum together. Such surgery often carries additional complications such as instability of the sternum, post-operative bleeding, and mediastinal infection. The thoracic muscle and ribs are also severely traumatized, and the healing process results in an unattractive scar. Post-operatively, most patients endure significant pain and must forego work or strenuous activity for a long recovery period.
Many minimally invasive surgical techniques and devices have been introduced in order to reduce the risk of morbidity, expense, trauma, patient mortality, infection, and other complications associated with open-chest cardiac surgery. Less traumatic limited open chest techniques using an abdominal (sub-xyphoid) approach or, alternatively, a "Chamberlain" incision (an approximately 8 cm incision at the sternocostal junction), have been developed to lessen the operating area and the associated complications. In recent years, a growing number of surgeons have begun performing CABG procedures using minimally invasive direct coronary artery bypass grafting (MIDCAB) surgical techniques and devices. Using the MIDCAB method, the heart typically is accessed through a mini-thoracotomy (e.g., a 6 to 8 cm incision between a patient's ribs or intercostal space) that avoids the sternal splitting incision of conventional cardiac surgery. A MIDCAB technique for performing a CABG procedure is described in U.S. Pat. No. 5,875,782, for example.
Other minimally invasive, percutaneous, coronary surgical procedures have been advanced that employ multiple small trans-thoracic incisions to and through the pericardium, instruments advanced through ports inserted in the incisions, and a thoracoscope to view the accessed cardiac site while the procedure is performed as shown, for example, in the above-referenced '468 patent and in U.S. Pat. Nos. 5,464,447, and 5,716,392. Surgical trocars having a diameter of about 3 mm to 15 mm are fitted into lumens of tubular trocar sleeves, cannulae or ports, and the assemblies are inserted into skin incisions. The trocar tip is advanced to puncture the abdomen or chest to reach the pericardium, and the trocar is then withdrawn leaving the port in place. Surgical instruments and other devices such as fiber optic thoracoscopes can be inserted into the body cavity through the port lumens. As stated in the '468 patent, instruments advanced through trocars can include electrosurgical tools, graspers, forceps, scalpels, electrocauteries, clip appliers, scissors, etc.
In such procedures, the surgeon can stop the heart by utilizing a series of internal catheters to stop blood flow through the aorta and to administer cardioplegia solution. The endoscopic approach utilizes groin cannulation to establish CPB and an intraaortic balloon catheter that functions as an internal aortic clamp by means of an expandable balloon at its distal end used to occlude blood flow in the ascending aorta. A full description of an example of one preferred endoscopic technique is found in U.S. Pat. No. 5,452,733, for example.
However, recently developed, beating heart procedures eliminate the need for any form of CPB, the extensive surgical procedures necessary to connect the patient to a CPB machine, and to stop the heart. These beating heart procedures can be performed on a heart exposed in a full or limited thoracotomy or accessed percutaneously.
In such percutaneous procedures, the epicardium of the beating or stopped heart is exposed for viewing typically by use of grasping and cutting instruments inserted through a port to cut through the pericardium surrounding the heart while the area is viewed through a thoracoscope or endoscope, e.g., inserted through a different port. Once the heart is exposed, it is necessary to locate the target coronary artery as well as the occlusion. In this case, it is not possible for the physician to manually palpate the fatty tissue overlying the artery and occlusion to accomplish this.
Fluoroscopy is widely employed during coronary catheterization to provide a real-time X-ray image to visualize the position of devices advanced within the vascular system of a patient. Bi-plane fluoroscopy, provides two real-time x-ray images acquired from different angles to visualize a totally occluded coronary artery. However, biplane fluoroscopy is costly and slow, and erroneous interpretation of the images often occurs.
A reliable technique is needed for precisely determining the relative positions of a therapeutic working device, the boundaries of an occlusion, and the structure of the occluded artery as the working device is manipulated or otherwise. Therefore, it has been proposed to employ instruments, e.g. catheters and guidewires, that can be advanced either through the artery lumen and the occlusion in the target coronary artery itself or via a percutaneous port lumen, or both, to identify suitable unobstructed sites of the target coronary artery for proximal and/or distal anastomoses.
A hand held probe is disclosed in U.S. Pat. No. 6,248,072 that is adapted to be advanced against the epicardium by the surgeon to determine the location of the target coronary artery and the occlusion within the arterial lumen. The probe incorporates an ultrasound transducer at the probe end in contact with the heart that emits and receives reflected ultrasound signals. The reflected ultrasound signals are processed in external equipment to develop images indicative of the tissue that the transducer is applied to by the physician. It is implied that unobstructed anastomosis sites can be determined by the characteristic display of an ultrasound image of an open arterial lumen. The physician may mistakenly locate and open the wrong vasculature lumen unless the physician knows approximately where the target coronary artery resides, because the probe only identifies lumens from cardiac tissue. In fact, it can be difficult to distinguish between a lumen of an artery and that of a vein. Smaller vessel diameters can also be harder to identify than larger diameter vessels. It appears the probe would be unable to precisely identify the targeted coronary artery. Further, in a closed-chest procedure, it can sometimes be very difficult to identify a specific area of the heart while viewing the heart with an endoscope having a limited field of view thereby making it difficult to precisely locate the targeted vessel.
The use of intravascular ultrasound catheters having distally disposed ultrasonic transducers is disclosed in U.S. Pat. No. 6,026,814. The '814 patent relates to systems for performing CABG almost entirely employing intravascular catheters and devices. In one embodiment of the '814 patent, a first ultrasound catheter is advanced from a surgically created opening in a peripheral artery, e.g., the femoral artery, to and through the occlusion in the target coronary artery to a distal anastomosis site. A second ultrasound catheter is advanced in a similar fashion into the lumen of the source vessel to locate a further ultrasound transducer at the site where the source vessel is to be anastomosed to the distal anastomosis site of the cardiac artery. The ultrasound transducers act as transmitters and receivers in order to guide the distal end of the source vessel to the distal anastomosis site. Instruments that are advanced through the source vessel are used to perform the arteriotomy in the target coronary artery at the distal anastomosis site and to anastomose the target coronary artery to the source vessel. According to the '814 patent, one of the ultrasound transducers is positioned in the lumen of the source vessel while the other is positioned in the target vessel. Therefore, the size of the vessels, i.e. the diameter of the vessels, will dictate the size or diameter of the ultrasound transducers or other types of transmitters and receivers. The '814 patent does suggest that a number of other cooperating transmitters and receivers, e.g., RF signal transmitter and receiver, one or more point light source and photodiode, electromagnet and magnetic field responsive element can be substituted for the ultrasound transmitter and receiver. However, these transmitters and receivers will be limited in size required to fit in a source vessel or a target vessel. The smaller size may limit the effectiveness of the transmitters and receivers. For example, the size of an ultrasound transducer can limit the distance and resolution that images may be acquired. Further, the length of the source vessel must be determined prior to guiding of the distal end of the source vessel to the distal anastomosis site. Therefore, the physician would need to know the exact length the source vessel must be prior to guiding of the vessel. If the physician chooses the wrong length, the source vessel may end up to short or to long, both of which may be detrimental to the creation of the anastomosis. In addition, it may be very difficult to manipulate and guide the source vessel having an ultrasound transducer inside itself to the target vessel.
The use of a hand held ultrasound instrument and system to pass a relatively stiff distal segment guidewire through a hardened obstruction that cannot be crossed by the typical soft tip guidewire is disclosed in U.S. Pat. No. 6,241,667. Typically, a guidewire is advanced from a surgically created opening in a peripheral artery, e.g., the femoral artery, to the occlusion in the target coronary artery and the guidewire (or a catheter advanced over the guidewire) is advanced through the occlusion. This approach of placing a variety of devices for performing procedures in the arterial system, e.g., at the occlusion, is well known in the field of interventional cardiology. The guidewire is maneuvered into place to act as a guide for positioning the placement of catheters or devices "over the wire." The guidewire outer diameter typically ranges from 0.010 to 0.038 inches whereas an interventional catheter lumen diameter typically ranges from 0.040 to 0.25 inches so that a combination of guidewire and interventional catheter can be selected that suits the vascular lumens of a particular vascular pathway.
In one embodiment of the '667 patent, an imaging locator comprising an imaging tube and an ultrasonic transducer is passed through an incision in the chest of a patient and positioned adjacent the surface of the heart and outside an occluded coronary artery. A catheter having a tissue-penetrating working element is disposed in the catheter delivery lumen of the imaging tube. During operation, the working element is advanced from the catheter delivery lumen and steered and manipulated through the arterial wall distal to the occlusion and advanced proximally to cross the occlusion retrograde while being imaged by the imaging locator. A guide catheter is then advanced from a surgically created opening in a peripheral artery, e.g., the femoral artery, to the proximal or upstream side of the occlusion in the target coronary artery. The working element is then advanced into the lumen of the guide catheter until it can be grasped outside the body, whereupon the guide catheter is removed.
Again, the physician may mistakenly locate and open the wrong vasculature lumen unless the physician knows approximately where the target coronary artery resides, and it may be difficult to distinguish between a lumen of an artery and that of a vein. Smaller diameter vessels may also be harder to identify than larger diameter vessels. Therefore, the imaging locator alone may be unable to precisely identify the targeted coronary artery. Furthermore, in a closed-chest procedure it can sometimes be very difficult to identify a specific area of the heart while viewing the heart with an endoscope having a limited field of view thereby making it difficult to precisely locate the targeted vessel.
U.S. Pat. Nos. 5,722,426, 6,080,175 and 6,113,588 disclose the use of light emission to assist in locating an occlusion in a target coronary artery by illuminating the arterial lumen with light that the surgeon can observe through a thoracoscope or directly when the epicardial surface is exposed to view in a thoracotomy. A hand held probe is disclosed in the '426 patent that is adapted to be inserted through an incision made in the target coronary artery upstream or downstream from the occlusion and advanced toward the occlusion to determine its respective upstream or downstream end. The probe incorporates a plurality of light sources along the probe end that emit light as the probe is advanced. It is asserted that the light can be seen through the vessel wall and that the light brightness is attenuated as the probe penetrates the occlusion. Unobstructed anastomosis sites can be determined by viewing the change in light brightness. Catheter borne light emitters are disclosed in the '175 and '588 patents. Again a catheter is advanced from a surgically created opening in a peripheral artery, e.g., the femoral artery, to and through the occlusion in the target coronary artery to a distal anastomosis site. The light transmitted through the arterial wall is observed, and it is asserted that unobstructed anastomosis sites can be determined by viewing the change in light brightness.
However, the ability of a surgeon to visually ascertain changes in light brightness of a light shining through a vessel wall either directly or through a thoracoscope can be hampered if the light is diffused in the tissue of the vessel wall or is blocked by an obstruction or any fatty tissue overlying the blood vessel and epicardium. The thickness of cardiac tissue and fatty deposits located between the coronary artery and the surface of the heart can vary greatly among patients. This variance in tissue thickness and fatty deposits can effective a surgeon's ability to accurately identify unobstructed anastomosis sites, since the surgeon's ability to visually ascertain changes in light brightness shining through a vessel wall can be diminished. Moreover, environmental conditions of the operating room, particularly the brightness of the room or the surgical field, can diminish the brightness of the transmitted light and make it difficult to see.
A further probe, referred to as the "H-Probe", is described by Verimetra, Inc. at www.verimetra.com/MEMS_Sensors_for_Surgery/H-Probe/h-prove.html. The H-Probe is described as a MEMS-based instrument designed to palpate vessels to determine the position of internal plaque. It is asserted that the MEMS-based vessel hardness H-Probe at the end of an MIS tool will minimize, if not eliminate, erroneous choices for bypass procedure location, leading to reduced post-operative complications.
While these approaches may hold promise, in some instances they are either unduly complicated to practice or not specific enough. Simple devices and methods that can positively identify vessels and suitable anastomosis sites with high specificity remain highly desirable. Such devices and methods would be useful in locating or tracking body vessels exposed in a surgical field but obstructed by overlying tissues.

Methods and apparatus for locating body vessels and occlusions in body vessels


A lighting panel comprises a light source and a light modifying panel positioned over the light source, in the form of a set of protrusions over the base, the protrusions facing the light source. The protrusions comprise circular/elliptical/polygonal cylinders or cone sections with a small cone taper angle.

Lighting panels in the form of a plate with multiple microlenses are known for use in luminaires, to hide the light source (such as a fluorescent tube or LED) and to deliver a preferred light distribution. The preferred light distribution can depend on national guidelines. For example, a microlens optics plate is widely used in Europe and acrylic plates are widely used in North America. Typically, these are made by hot embossing which is a relatively costly batch process (highly dependent on the base material) and limited to plate materials. Three dimensional lenses or exit windows beyond a single curve are therefore hard to obtain.
WO 2005/083317 describes a microlens optics plate for use in luminaires. The plate is a transparent substrate with tapered protrusions that end in a sharp point or in a sharp edge. Most of the light enters the plate via the flat side and exits via refraction at a tapered conical surface. The plate transmits part of the light from a diffuse source within a limited intensity cone (the intensity distribution required to comply with EU regulations) and recycles the remaining part back to the source, where it is reflected and has a second chance to pass the plate.
In designing office luminaires there are a number of optical problems that have to be taken into account.
The actual preferred light intensity distribution depends on the region. In Europe, office luminaires have to comply with EN-12464-1 which prescribes certain horizontal task illumination Lux levels and has strict glare rules that limit the luminaire luminance at large angles with respect to the normal.
In North America the glare limits are less strict, which allows for more light at large angles. The advantage of this is a larger luminance spacing (giving lower cost) and more vertical luminance (better lighting of the walls). The drawback is a lower utilisation efficiency (less light to the task area) and more glare.
Especially for LED lighting, it is necessary to reduce the brightness of the LED source. The high brightness of LEDs can give discomfort glare. High peak brightness typically means a dotty but efficient product. High brightness is especially problematic under angles that are directly in the field of view of an office worker. The luminaire directly above a person is not directly visible and can therefore have a higher brightness than further away when it is within a person's visual field. Typically, the visual field of a person looking straight ahead starts at about 35 degrees with respect to the vertical orientation. Therefore, there is no direct glare from luminaires at viewing angles between 0 and 35 degrees with respect to the vertical. In general, the discomfort glare by a high luminance source in the ceiling increases with increasing angle to the vertical plane (assuming that the people in the room look straight ahead or downward to a screen or desk).
Thus, high peak brightness should be avoided at large angles to the vertical (i.e. for rays with a large vector component in the plane of the luminaire exit window and ceiling), but higher values may be permitted at low angles (i.e. for rays directed downwardly from the ceiling). Since high homogeneity comes at the cost of decreasing optical efficiency, generally requiring more light recycling, it is preferable to homogenize the luminance only at higher viewing angles where it is really required.


Features for a restraint, such as a cap, are described. The restraint secures a cardiac device in a collapsed, delivery configuration for transcatheter delivery to a heart. The restraint may have a tubular sidewall extending from a proximal end to a distal end, a proximal opening defined by the sidewall at the proximal end and a channel defined by the sidewall and extending distally from the proximal opening. The restraint is configured to receive the implant in the collapsed configuration through the proximal opening to radially restrain the implant within the channel. The restraint eliminates the need for a surrounding sheath, reducing the delivery profile and size of the overall delivery system, among other advantages. The restraint may have an atraumatic leading edge to reduce the risk of injury to the patient.

Heart valve incompetency is a serious problem. For example, heart disease can cause the chambers of the heart to expand and weaken. With specific reference to the mitral valve, as result of aging or disease, the left ventricle dilates, and the papillary muscles are displaced. Consequently, the annulus of the mitral valve dilates excessively. In this state of dilation, valve leaflets may no longer effectively close, or coapt, during systolic contraction. Consequently, regurgitation (or retrograde flow back across the valve that should be closed) of blood occurs during ventricular contraction, and cardiac output is decreased.
This condition may be addressed by the surgical implantation of an implant. This procedure is performed open chest and is time consuming. In open heart surgery, the patient is put on cardiopulmonary bypass with its associated risks of morbidity and mortality due to stroke, thrombosis, heart attack and extended recovery time.
Improvements in this field are therefore desirable.

Deployment restraint and delivery system for implantable cardiac device


A receiver processes an NMR signal to produce a baseband image information signal from which two quadrature component signals are derived. An intermediate frequency section mixes the received NMR signal with two reference signals to shift the image information into a frequency band having a bandwidth BW and centered at a frequency that is 1.5 times the bandwidth BW. The resultant signal is filtered to remove extraneous signals outside the image information band. An analog to digital converter samples the filtered signal at a rate that is twice the bandwidth BW and digitizes the samples into a digital signal. A quadrature detector derives I and Q output signals from the digital signal by alternately selecting digital samples and negating every other sample selected for each of the I and Q output signals. The quadature detector also digitally filters the I and Q signals which are then used to construct an NMR image.

The field of the invention is nuclear magnetic resonance (NMR) imaging methods and systems. More particularly, the invention relates to an RF synthesizer and transmitter for producing RF excitation pulses having a precise frequency and phase, and a receiver for accurately receiving, demodulating and digitizing the resulting NMR signals.
Any nucleus which possesses a magnetic moment attempts to align itself with the direction of the magnetic field in which it is located. In doing so, however, the nucleus precesses around this direction at a characteristic angular frequency (Larmor frequency) which is dependent on the strength of the magnetic field and on the properties of the specific nuclear species (the magnetogyric constant .gamma. of the nucleus). Nuclei which exhibit this phenomenon are referred to herein as "spins".
When a substance such as human tissue is subjected to a uniform magnetic field (polarizing field B.sub.0), the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field, but precess about it in random order at their characteristic Larmor frequency. A net magnetic moment Mz is produced in the direction of the polarizing field, but the randomly oriented magnetic components in the perpendicular, or transverse, plane (x-y plane) cancel one another. If, however, the substance, or tissue, is subjected to a magnetic field (excitation field B.sub.1) which is in the x-y plane and which is near the Larmor frequency, the net aligned moment, M.sub.z, may be rotated, or "tipped", into the x-y plane to produce a net transverse magnetic moment M.sub.t, which is rotating, or spinning, in the x-y plane at the Larmor frequency. The degree to which the net magnetic moment M.sub.t is tipped, and hence, the magnitude of the net transverse magnetic moment M.sub.t depends primarily on the length of time and magnitude of the applied excitation field B.sub.1 and its frequency.
The practical value of this phenomenon resides in the signal which is emitted by the excited spins after the excitation signal B.sub.1 is terminated. In simple systems the excited nuclei induce an oscillating sine wave signal in a receiving coil. The frequency of this signal is the Larmor frequency, and its initial amplitude, A.sub.0, is determined by the magnitude of the transverse magnetic moment M.sub.t. The amplitude, A, of the emission signal decays in an exponential fashion with time, t: EQU A=A.sub.0 e.sup.-t/T2*
The decay constant 1/T.sub.2.sup.* depends on the homogeneity of the magnetic field and on T.sub.2, which is referred to as the "spin-spin relaxation" constant, or the "transverse relaxation" constant. The T.sub.2 constant is inversely proportional to the exponential rate at which the signal decays, at least in part due to a dephasing of the aligned precession of the spins after removal of the excitation signal B.sub.1 in a perfectly homogeneous field.
Another important factor which contributes to the amplitude A of the NMR signal is referred to as the spin-lattice relaxation process which is characterized by the time constant T.sub.1. This is also called the longitudinal relaxation process as it describes the recovery of the net magnetic moment M to its equilibrium value along the axis of magnetic polarization (z). The T.sub.1 time constant is longer than T.sub.2, much longer in most substances of medical interest. If the net magnetic moment M is not given sufficient time to relax to its equilibrium value, the amplitude A of the NMR signal produced in a subsequent pulse sequence will be reduced.
The NMR measurements of particular relevance to the present invention are called "pulsed NMR measurements". Such NMR measurements are divided into a period of RF excitation and a period of signal emission and acquisition. These measurements are performed in a cyclic manner in which the NMR measurement is repeated many times to accumulate different data during each cycle or to make the same measurement at different locations in the subject. A wide variety of preparative excitation techniques are known which involve the application of one or more RF excitation pulses (B.sub.1) of varying magnitude, frequency content, phase and duration. Such RF excitation pulses may have a narrow frequency spectrum (selective excitation pulse), or they may have a broad frequency spectrum (nonselective excitation pulse) which can produce transverse magnetization M.sub.t over a range of resonant frequencies. The prior art is replete with RF excitation techniques that are designed to take advantage of particular NMR phenomena and which overcome particular problems in the NMR measurement process.
After an excitation pulse, the NMR imaging system receives the radio frequency signals emitted by the excited nuclei and uses these signals to construct an image of the patient. The received signals containing "image information" lie in a band of frequencies centered at the Larmor frequency. Before the image information can be extracted to construct an image of the patient, this band of frequencies must be demodulated by shifting it to lower frequencies. Conventional signal conversion is employed to shift the band of frequencies by mixing the image information signal with a reference signal. Unless properly filtered out, noise in a band of frequencies that is symmetrical about the reference signal frequency with the image information band will become superimposed onto the image information in the resultant signal produced by the heterodyning.
This problem can be avoided if quadrature receivers are used to bring the image information to baseband. The use of in-phase (I) and quadrature (Q) demodulation allows frequencies on either side of a reference frequency to be distinguished, if the phase and amplitude adjustment of the I and Q signal channels is exact. Unfortunately such precise adjustment is difficult and misadjustment can cause some of the energy on one side of the reference frequency to be misassigned to the other side (poor "image" rejection). In addition, low frequency (e.g. 1/F) noise may be introduced into the image information signal and degrade its quality.
Heretofore, the signal processing that demodulated the image information and produced the two quadrature signals was performed in the analog domain. From a noise immunity standpoint, it is advantageous to convert the image information signal into the digital domain as early in the processing as possible. With the advent of high performance digital circuits and programmable signal processors, it is becoming possible to rapidly perform complex signal processing digitally.

Radio frequency receiver for a NMR instrument


A method of etching a carbon-containing layer on a semiconductor substrate using a Si-containing gas and a related method of fabricating a semiconductor device in which a plurality of contact holes having excellent sidewall profiles are formed by etching an interlayer insulating layer using a carbon-containing layer pattern formed in accordance with the invention and having a width of several tens of nm as an etch mask are provided. To etch a carbon-containing layer to be used as a second etch mask, a first mask pattern is formed on the carbon-containing layer to partially expose a top surface of the carbon-containing layer. The carbon-containing layer is then anisotropically etched with a plasma of a carbon-etching mixture gas formed of O2 and a Si-containing gas using the first mask pattern as a first etch mask to form the carbon-containing layer pattern. Neighboring contact holes in a high-density cell array region fabricated in accordance with this invention are distinctly separated from each other, even when an interval between the neighboring contact holes is as small as several tens of nm or less; and, thus, a short-circuit between neighboring unit cells using such contact holes can be prevented.

1. Field of the Invention
The present invention relates to an etching method for use in connection with semiconductor device fabrication and to a method of fabricating a semiconductor device using the same, and more particularly, to a method of etching a carbon-containing layer using a new etching gas and to a method of fabricating a semiconductor device using the same.
2. Description of the Related Art
As semiconductor devices have become more integrated and the feature size thereof has correspondingly decreased, the horizontal areas of the semiconductor devices have also decreased while the thicknesses of such semiconductor devices have increased. As a result, the heights of unit elements and contacts for electrically connecting the unit elements have increased, and thus, the aspect ratios of the corresponding contact holes have also increased. In the etching process for forming a pattern having such an increased aspect ratio, the thickness of a layer to be etched is greater and there is essentially no etching process margin due to the height of the photoresist pattern that needs to be used. Therefore, the thickness of the photoresist layer is decreased, and a relatively thin photoresist layer leads to a number of problems. To solve the problems associated with the photoresist pattern being thin, a technique of using an amorphous carbon layer (ACL) as an etch mask has been developed (See U.S. Patent Laid-open Publication No. 2004/0079726 A1), the disclosure of which is incorporated herein by reference.
An etch mask including an ACL for forming a fine pattern of a highly-integrated semiconductor device (on the scale of microns or smaller) may be an etch mask including a multilayer structure in which an ACL, a capping layer, and a photoresist layer are sequentially stacked on a film to be etched on a substrate. In this case, a photoresist pattern is formed through exposure and development processes, and that pattern is transferred to an anti-reflection layer and the capping layer, thus producing a capping layer pattern. The ACL is etched using the capping layer pattern as a first etch mask, and the capping layer pattern is thereby transferred to the ACL, thus producing an ACL pattern. The thus formed ACL pattern is then used as a second etch mask for etching the film to be etched on the substrate. After the film to be etched is etched, residues and etching byproducts of the ACL pattern are removed through ashing and stripping processes.
The ACL of the etch mask having the multilayer structure as described above includes carbon as a primary component. Accordingly, an etching gas commonly including O2, N2, or a combination thereof may be used to etch the ACL. The capping layer interposed between the ACL and the photoresist layer is preferably formed of a material, for example, SiON or SiO2, which has strong etch resistance to components (such as O2 and N2) which are used as the ACL etching gas, and which also enables low-temperature deposition.
However, as semiconductor devices have become more highly integrated and the width of unit elements has correspondingly decreased, the thickness of the photoresist layer has become reduced, and, accordingly, the thickness of the capping layer has also become reduced. When etching an ACL using a relatively thin capping layer as a first etch mask, the etch selectivity between the capping layer and the ACL layer becomes a critical factor in obtaining an excellent sidewall profile of an ACL pattern to be used as the second etch mask in the succession of etching steps. Particularly, when an ACL is etched using plasma, the capping layer is sputtered by ions, thereby additionally degrading the etch resistance of the capping layer.
In the prior art, to increase the etch resistance of a relatively thin capping layer used as an etch mask for etching an ACL, a fluorocarbon series gas may be injected so that a protective carbon series polymer is stacked on the capping layer. However, since an ACL includes carbon as a primary component, an etching gas that includes N2 or O2 must be used to etch the carbon. Thus, when etching the ACL using an etching gas that also includes the fluorocarbon series gas, it is difficult to deposit the protective carbon series polymer on the capping layer, and, accordingly, a desired etch selectivity of the ACL relative to the capping layer is difficult to obtain.
To form a fine pattern, e.g., a contact hole pattern, that is beyond the ordinary resolution limit of a photolithographic process, the shape of a hole (as defined by an etch mask) that is needed to form the contact hole or other fine pattern is commonly required to have a smaller critical dimension (CD) in the bottom or lower portion thereof than in the top or upper portion, which is an inlet of the contact hole. Accordingly, the ACL pattern obtained by etching the ACL should preferably be formed with an inclined or cone-shaped sidewall profile to reduce the CD of the bottom of the hole relative to the inlet opening at the upper portion of the hole. To obtain such an inclined sidewall profile, a polymer acting as an etch mask could be deposited on sidewalls of the hole being formed by etching the ACL. However, it is difficult to etch the pattern with the inclined sidewall profile following such polymer deposition.
These and other problems with or limitations of the prior art techniques are overcome in whole, or at least in part, by the methods of this invention.

Method of etching carbon-containing layer and method of fabricating semiconductor device


A method of preserving symmetrical routing in a communication system comprising a server farm connected to the Internet through an Internet access router. The server farm includes at least two customer cabinets with at least a WEB server and at least two firewalls. The firewalls use a Virtual Router Redundancy Protocol (VRRP) to set up one firewall as being the primary firewall. The method includes checking in each firewall whether there is a change of the VRRP state from primary to secondary or reciprocally. Such a change indicates that a link between the primary firewall and one of the customer cabinets has failed. The link is disabled from the network to the firewall the state of which has changed from primary to secondary or the link is enabled from the Internet network to the firewall the state of which has changed from secondary to primary.

A server farm is a physical location having a scalable infrastructure and facilities and resources enabling users connected to the Internet network to easily access a number of services provided by a plurality of customers hosted by the server farm. Generally, the resources are located in premises owned by a data processing equipment provider such as the IBM Corporation.
Most server farms are used today to host Internet related devices (for example WEB servers) of several customers. The architecture of such a server farm includes a local network to which are connected the customer cabinets and an Internet front-end connecting this local network to the Internet. Such a local network includes different layers of components such as switches and firewalls through which requests from the users connected to the Internet are routed towards the customer cabinets.
The firewalls are intermediary devices between the local Network and the front-end. They are connected by a LAN to an Internet Access Router (IAR) which is directly connected to the Internet. For redundancy, there are two firewalls connected to the IAR, a primary firewall and a secondary firewall. At a given time, all communications are established through the primary firewall. If the primary firewall fails, the secondary firewall becomes the primary firewall and all the communications pass through it.
The firewalls present all the characteristics of a router with the addition of security filtering features known as firewall rules. A firewall may also have the capability to inspect IP packets and track the state of sessions through the firewall established between two devices separated by the firewall. This capability, which is known as "Statefull Inspection", includes checking that every backward connection is associated with an existing forward connection and following the state of a connection to allow only packets that are in the right sequence level of the connection to proceed. This means that, if a connection is established from an end user to a WEB server (forward path) through a first firewall, all the responses coming from the WEB server to the end user (reverse path) will have to go through this firewall. If any firewall receives a reverse path frame without having received a forward path frame, it will drop the reverse frame. If any firewall receives a data packet while the session is only at the connecting state, it will drop the data packet.
In the local network, a protocol such as the Virtual Route Routing Protocol (VRRP) is used between the firewalls. VRRP allows the customer WEB servers to see the redundant firewalls as a single virtual firewall. At any instant, only one firewall really owns the virtual firewall function based on the availabilities of the firewall interfaces or on static priorities associated with them by configuration. The individual interface having the highest priority is the one elected to own the virtual firewall interface and the associated firewall acts as the virtual firewall until it fails or until another interface with a higher priority appears. A first firewall (called the primary firewall) can own the virtual firewall function for a subset of the customer servers while the other firewall (called the secondary firewall) can own this role for another set of customers. In other words, the first firewall or primary firewall owns the primary interface of the VRRP group of interfaces to each one of these customer servers.
At least two firewalls connect the local network to the Internet network. As a result, there is a routing problem, since the customer WEB servers attached thereto may be reached by at least two different paths going through each firewall. Because of the Statefull Inspection mode in the firewalls, the forward path must be identical to the reverse path, resulting in what is known as symmetrical routing.
One requirement is to allow different customer WEB servers (in different cabinets) to communicate between themselves. This means that all customer servers must have the same primary firewall by configuration in order to provide the symmetrical routing. In case of firewall failover, all the customer servers must be switched over the secondary firewall. Also by configuration, the firewalls are setup so that a first firewall, which is the primary firewall for all the customer servers, is chosen by default as the firewall to be used by the IAR when both firewalls are operational.
But there is a problem when a link between the first firewall which is the primary firewall being used and the customer WEB servers fails. In such a case, all the frames from the customer servers go through a second firewall. However, the IAR will keep selecting the first firewall as the path to route the frames from the Internet to the customer servers. Therefore, symmetric routing is not preserved, as the forward path for the customer servers is through a firewall whereas the reverse path is through the other firewall. This results in dropping all reverse path frames by the latter firewall.

This patent is subject to a terminal disclaimer.

Preserving symmetrical routing in a communication system based upon a server farm

International Business Machines Corporation


Detecting at least one of an echo detector and a noise detector based on analysis of audio streams transmitted to and received from each endpoint of a conference. When certain characteristics of the respective audio streams for a given endpoint are classified as significant against certain criteria, a determination is made as to whether that endpoint is a source of echo and/or noise. Subsequent actions are taken to alert users and/or prevent broadcast of impaired signals.

When participating in a teleconference, participants often use a wide range of devices and different types of connections. This may lead to quality issues that arise due to the presence of one or more contributing sources of undesired audio. In such scenarios, impaired signals are broadcast to all participants, often making the teleconference difficult or impossible to conduct.


A rotary pump for pumping fuel for internal combustion engines in the form of a vane pump or gear and rotor pump with pumping chambers disposed circumferentially around the rotor. The chambers progressively increase in the inlet area of the pump to draw in fuel and progressively ensmall at the outlet area to discharge fuel under pressure to supply an engine. The pulsations initiated in the pump are absorbed in the pump by a closed chamber exposed to the pump outlet flow, the chamber having flexible walls and an internal pressure above atmospheric to reduce pulses in the outlet and resulting pump noise. The chamber is blow molded with an enclosed volume surrounded by flexible walls.

Rotary fuel pumps driven by an electrical powering device have been utilized for some years in some vehicles either as original equipment or as appliances to supplement the original fuel supply system. The pump and power unit are frequently in a common housing as shown, for example, in U.S. Pat. No. 4,401,416, issued Aug. 30, 1982 to Charles H. Tuckey.
Since the pumps are frequently mounted in the fuel tanks of a vehicle, the noise factor is extremely important. A pump under load will normally produce more noise and this may be audible as a humming noise, to an annoying degree, to passengers in the vehicle.
It will be appreciated that in the pumping cycle, as one pumping cell is exhausting, another cell is taking in fluid at the same time. In other words, intake and exhaust pressure waves are timed with one another, and normally the quantity of fluid being exhausted from each cell is the same as that being taken in by another cell.
It is an inherent characteristic of a positive displacement pump to produce slight pressure pulses each time one of the multiple vanes passes through its pumping cycle. For example, a roller vane rotary pump produces an audible humming noise when operating at system pressure. This noise has a tendency to increase as the output pressure requirement is increased.
It has been a desire of manufacturers and users of positive displacement rotary pumps to reduce or eliminate pressure pulses in order to achieve a smooth, pulse-free flow of fluid out of a pump at desired operating pressure.
An object of the present invention is to allow the exhaust pressure peaks to counter the negative inlet pressure valleys thereby cancelling one another and attaining a smooth flow in and out of the assembly and at the same time reducing the pump noise.
This concept involves the utilization of a resilient member between the inlet and exhaust zones within the pump assembly. Thus, each time a pressure peak occurs in the exhaust fluid, the pressure can force the resilient member to yield or move toward the inlet fluid, thereby simultaneously off-setting the negative pressure which occurred at the same time on the inlet side.
It has been noted that pressure waves or pulses are preset at the inlet, as well as the outlet, at all operating pressures.
One must acknowledge and deal with the extreme pressure differential between the inlet and exhaust sides of the pump. For instance, the inlet zone is usually at an average pressure close to atmospheric; and the outlet zone average pressure is much higher, i.e., 60 psi or more depending upon the operating pressure requirement of the pump.
Hollow pulse absorbing chambers in fuel pumps have been proposed previously as exemplified in U.S. Pat. No. 4,181,473 to Yoshifumi issued Jan. 1, 1980 and U.S. Pat. No. 4,521,164 to Tuckey issued June 4, 1985.
In the present invention a hollow pulse modulator of a flexible plastic material is proposed formed by a blow molding process in which the internal pressure within the walls of the hollow chamber is above atmospheric and introduced into the chamber during the molding process.
Other objects of the invention will be apparent in the following description and claims in which the invention is described, together with details to enable a person skilled in the art to practice the invention all in connection with the best mode presently contemplated for the invention.


An adapter for electrical connections of a car radio has a plastic part containing integrated electrical plug-in connection arrangement and mechanically fixable to a car component that does not have any electrical connection with the adapter.

1. Field of the Invention
The invention relates to an adapter for the electrical connections of a car radio.
2. Description of the Related Art
On their rear side, car radios have plug-in connectors which are used to set up a connection to a cable harness in the vehicle. There are a wide variety of embodiments and configurations of the plug-in connectors. This results in the problem that not every car radio can be readily connected in each vehicle since the plug-in connectors on the car radio and on the cable harness of the vehicle are designed differently. On one hand, this makes it more difficult for the end user to retrofit a car radio and, on the other hand, requires the car radio manufacturer, during initial installation, to constantly adapt the plug-in connectors to the differently designed plug-in connectors of various vehicle manufacturers or sometimes even to various plug-in connectors of various vehicle models of a single manufacturer. As a result, different variants of the device are required solely on account of the different plug-in connectors. In addition to considerable development and tool costs, this also leads to increased logistical complexity.
As an alternative to adapting the plug-in connectors of the car radio to the special plug-in connector of the vehicle cable harness, use may be made of adapter cables which have the respective compatible mating connectors for the car radio and the cable harness at their ends. In this case, a separate adapter cable is then generally required for each plug-in connection, thus resulting in increased plug-in complexity during installation of the radio and in a confusing installation situation ("cable clutter") in the case of preinstalled adapter cables.
Therefore, it is an object of the invention to specify an adapter for electrical connections of a car radio, the adapter avoiding the abovementioned disadvantages and facilitating installation.


A button input apparatus with a display function, which generates a switch signal in response to a user's press, and a portable electronic device having the same. The button input apparatus includes: a plurality of lever buttons each having a transparent window in at least a portion thereof, and one fixed edge on one side of the transparent window, so that the buttons are elastically vertically flexible; a switch substrate, which is disposed below the plurality of lever buttons, including openings respectively corresponding to the transparent windows, and generating a switch signal according to a motion of any of the plurality of lever buttons via a plurality of switches disposed to respectively correspond to elastic parts of the lever buttons; and a display panel, which provides an image in an area corresponding to each of the transparent windows, at least a portion of the display panel being disposed below the plurality of lever buttons.

1. Field of the Invention
The present invention relates to a button input apparatus with a display function and a portable electronic device having the same, and more particularly, to a button input apparatus with a display function, which displays images via windows included in a plurality of lever buttons disposed over a display panel and provides a user with a good sense of input in spite of its thinness, and a portable electronic device having the button input apparatus.
2. Description of Related Art
In general, a button input apparatus generates a switch signal in response to a user's press of a button and outputs the generated switch signal. When a user presses a button, the button input apparatus senses the user's input via an elastic member which moves downward and is then restored to its initial position. A dome shaped metal is usually used as the elastic member.
Recently, button input apparatuses having a display function have been suggested. However, when a button input apparatus is thin, it is difficult to provide a user with a good sense of input, and when a button input apparatus is thick, although a user has a good sense of input, it is difficult to assemble the button input apparatus due to its thickness and/or due to a complex structure thereof.

Button input apparatus with display function and portable electronic device having the same


A non-isolating AC-DC voltage converting system has two voltage converters. The first voltage converter receives a bus voltage and turns on a power transistor when the bus voltage is at valley regions and to provide an interim voltage which is lower than the bus voltage. The second voltage converter receives the interim voltage and provides an output voltage of the AC-DC voltage converting system.

In the field of Alternating-Current to Direct-Current (AC-DC) voltage converters, considering the high input voltage of mains power, isolated voltage converters are widely used. However, the cost of an isolated voltage converter is high and the system is complex due to the usage of voltage transformer. Accordingly, non-isolating AC-DC voltage converters are required. However, due to the high voltage of mains power, the power efficiency of a conventional non-isolating voltage converter is low. Besides, the isolation between high voltage and low voltage in a semiconductor die and signal processing are challenging and integration for non-isolating AC-DC voltage converter is low.
In view of at least one of the above deficiencies, an improved solution is required.

Voltage converting circuit and associated chip package and converting method


This invention provides improved body length adjustment value structure for a vacuum powered lifting system of the type that embodies a variable length lifting body responsive to the differential of pressure inside that body with atmospheric pressure to resolve critical manual control problems. Thus control is provided by proportional movement of a control member over a substantially linear range producing a smooth progressive movement of the lifting mechanism. This permits non-critical lowering and release of a work load object by unskilled operators. Thus, an air injection valve with an air release port, is positioned within the lifting body having an elongated slot operable over a control range proportionately change the body length by release of a progressively increasing flow of air into the body to increase air pressure and body length over the critical range of lowering and releasing the work load object in response to a corresponding substantially linear movement of the control member. Variable adjustment value structure establishes a known upper lift limit by control of the length of the body both under loaded and unloaded conditions, and provisions are made to keep a vacuum responsive work object grasping mechanism continuously operable.

Vacuum powered lifting and transport systems are known in the prior art. One example is shown in U.S. Pat. No. 4,413,853, S. Andersson, Nov. 8, 1983, wherein a tubing that changes length with internal air pressure is shortened by means of a vacuum source to lift a work object by vacuum suction and transport it to another location.
While these vacuum powered type of lifting and transport systems have advantages in engaging, lifting and transporting work load objects weighing 200 pounds or more along assembly lines in a factory, for example, several problems and deficiencies are present in such prior art systems that have limited their usefulness. Some limitations have made such systems potentially dangerous, in that heavy work load objects are critical to control and may be inadvertently dropped from the lifting mechanism or inaccurately positioned with uncontrollable speed.
It has been found in accordance with this invention for example that air pressure control systems employed in vacuum powered lifts to engage, lift, transport and release heavy work load objects have critical ranges of load positioning and work object grasping and releasing procedures requiring significant concentration and skill by an operator. In particular, operators must become very skilled in controlling air pressure changes particularly when lowering heavy work load objects to a terminal location under transition conditions from near atmospheric pressure to minimum pressures supplied by a vacuum source, to prevent premature release or mispositioning of the work object, which can impact with accompanying danger of damage to equipment or operator.
Criticality in atmospheric controls in such systems also are encountered as well as other deficiencies, such as (1) variations in performance and positioning of the lifting mechanism when loaded and unloaded; (2) the possibility of work object grasping failures; and (3) malfunctioning or mispositioning due to critical manual operational conditions in pressure control mechanisms.
It is therefore an object of the invention to provide improved vacuum powered lift and transport systems and controls overcoming the foregoing problems encountered in the prior art.
Other objects, features and advantages of the invention will be found throughout the following description, drawings and claims.

Vacuum control system for lifting systems


A sealing glass composition comprising, in wt. %, 30-70% lead oxide, 30-60% vanadium oxide, 1-10% phosphorous oxide, 0-30% bismuth oxide, 0.5 to 5% niobium oxide, and 1-15% of at least one oxide from the group consisting of tellurium oxide and selenium oxide.

The present invention relates to sealing glass compositions. More particularly, the invention relates to sealing glass compositions for bonding ceramics and still more particularly to compositions useful in bonding ceramics with satisfactory bond strength even when fired at temperatures of less than 400.degree. C.
Semi-conductor devices or chips, also known as "dies", are packaged in hermetically sealed ceramic containers to resist breakage and destruction. Such ceramic packages may be made of alumina, silicon carbide, silicon nitride, or other ceramics. A common packaging material is alumina (Al.sub.2 O.sub.3).
Ceramic packages of the type described are typically sealed by applying a sealing glass composition to the surfaces of the ceramic components and then heating them to elevated temperatures to effect bonding. One problem which has arisen in connection with such ceramic packages is that the sealing glass compositions heretofore known have typically required firing at temperatures of 400.degree. C. or higher to achieve bonding of the ceramic components with satisfactory bond strength. For example, sealing glasses based on lead borate systems, such as have been commonly used, required firing at 430.degree. C. to produce the desired bond strength. However, many of the new semi-conductor dies are much more sensitive to firing temperature and their usefulness will be adversely affected by exposure to temperature over 400.degree. C. Dies which are sensitive to firing temperature include larger dies and dies employing fine line geometry. In the latter case, lines of Si-SiO.sub.2 -Si which are spaced 1 to 2 microns apart are provided at the die surface. Firing at high temperatures to accomplish bonding tends to destroy the usefulness of these dies due to incipient melting of the line compositions which may result in undesirable contact between the lines.
It is therefore desirable to be able to provide a ceramic package which does not require firing at these elevated temperatures to achieve satisfactory bond strength.


A self-decoupled RF coil and method for adjusting the same is disclosed. The RF coil is an array of elements including at least one loop. Electromagnetic coupling between elements in the array causes an induced current in the at least one loop. The induced current has two modes. A reactance inserted in the at least one loop balances the two modes. The balanced current modes cancel. This cancelation results in self-decoupling of at the least one loop from the other elements in the RF coil array.

Radio frequency (RF) arrays consisting of a plurality of elements are desirable for parallel imaging and parallel transmission in magnetic resonance imaging (MRI). In general, parallel imaging and parallel transmission are improved as the number of elements in the RF array increases. For example, given two arrays that differ in the number of elements, the array with more elements may offer improved imaging characteristics, such as signal-to-noise ratio (SNR), acquisition time, and/or uniformity. Unfortunately, increasing the number of elements results in an increase in electromagnetic (EM) coupling between the elements. EM coupling affects the performance of the RF array negatively and can reduce the efficiency of the coil because energy that could be delivered to a subject is coupled between array elements instead. Accordingly, it is desirable to reduce EM coupling (i.e., coupling) between elements in an RF coil array.
There exists a variety of methods to reduce coupling (i.e., increase decoupling) in an array. One method includes overlapping adjacent elements in the array. Another method includes incorporating inductive/capacitive (L/C) networks connecting elements of the array. Still another method includes incorporating an auxiliary resonator with the elements array. These methods may significantly reduce coupling between adjacent elements however, these methods are less effective in reducing coupling between non-adjacent elements and may reduce the array's efficiency.
Recently, there has been interest in using mixed-type arrays for MRI. A mixed-type array includes a plurality of elements of different types. For example, a mixed array may include various combinations of elements selected from a group including dipoles, monopoles, and loops. Dipole elements for MRI are described by Raaijmakers, et al., in "Design of a Radiative Surface Coil Array Element at 7T: The Single-Side Adapted Dipole Antenna," Mag. Res. in Med., 66, pgs. 1488-1497 (2011). Monopole elements for MRI are described by Hong, et al. in "New Design Concept of Monopole Antenna Array for UHG 7T MRI," Mag. Res. in Med., 71, pgs. 1944-1952 (2014). These references are hereby incorporated by reference in their entirety.
Mixed-type arrays also require decoupling between elements. Unfortunately, the methods for decoupling described above are typically unsuitable for mixed-type arrays.
A need, therefore, exists for an array having significant decoupling between adjacent and non-adjacent elements, wherein the decoupling technique is suitable for arrays having elements of mixed types.


A system and method for measuring the radial runout of a shaft, rotatably supported on a standard rest, includes at least a first journal surface sensing assembly, a second journal surface sensing assembly, and a test surface sensing assembly which sense the radial position of the first journal surface, the second journal surface, and a test portion of the shaft, respectively, during rotation of the shaft. A transmitter of each surface sensing assembly transmits a runout signal which is received by a receiver of a computer. Within the computer, the runout signal from the test surface sensing assembly is adjusted with the runout signals from the first and second journal surface sensing assemblies to factor out deflection of the shaft caused by the standard rest and the shaft runout is computed and plotted using the normalized runout data.

This invention relates to apparatus and methods for measuring the radial runout of rotating objects. More specifically, the invention relates to apparatus and methods for measuring the radial runout, or circumferential out-of-roundness deviation of a shaft.
Conventional methods of inspecting and measuring the runout of shafts and other such similar parts require the use of precision supports for rotation of either the inspection part or the measurement gauge to establish the parts center or a reference surface. Setup and use of these devices generally requires the labor of several highly trained and skilled technicians. The inspection operation can be very time consuming, labor intensive, expensive and tedious to perform. In some cases, it is extremely difficult to utilize current methods of inspection. This is especially true for large rotating objects, such as generator rotors and turbine assemblies.
Conventional shaft runout measurement techniques typically require the presence of at least two operators. First, the surface of the shaft is prepared by cleaning and ensuring that there are no raised edges which might harm a contact-type gauge. Eight points are then marked around the circumference of the rotor coupling at evenly-spaced intervals of forty-five degrees. The shaft is supported at each end in a precision center, such as a lathe, and is rotated for a predetermined period of time to eliminate weight-induced bowing. As the shaft continues to rotate slowly, one operator positioned near the rotor coupling signals the other operator when each point passes a fixed reference point, the other operator reads the measured runout at five runout points and manually records the measurements. The five runout points include one point on each journal, one point on each coupling and one point intermediate the journals/couplings. All runout measurements are recorded as positive numbers, as only the total indicator runout (TIR) is of interest. On average, the runout measurement operation is performed fifteen times on different sections along the axial length of the rotor. If appropriate, axial runout measurements and shaft float measurements are also taken, axial runout points are adjusted using acceptance tolerances to reflect the actual axial runout, and the values of such measurements are manually recorded. The data collected during the measurement of the runout are then entered into a computer program, such as a spreadsheet, which solves for the Cartesian formula and the runout is manually plotted. After review and approval, the hard-copy runout report is generally stored for archival purposes. When this method is utilized, Runout measurements must be taken each time the machining setup is changed and is generally redone at each shift change to ensure proper setup of the shaft.
As may be easily appreciated, such conventional apparatus and method is man-power intensive and is therefore relatively expensive. Further, the measurement data is handled by personnel four separate times, allowing extensive opportunity for the introduction of error. In addition, the recorded data and the runout plots must be converted to an electronic format if they are to be archived in such form.
Briefly stated, the invention in a preferred form is a system and methods for measuring the radial runout, or circumferential out-of-roundness deviation of a shaft rotatably supported on a standard rest. The shaft includes a coupling, first and second journal surfaces.
The shaft runout measurement system comprises multiple surface sensing assemblies, including at least a first journal surface sensing assembly, a second journal surface sensing assembly, and a test surface sensing assembly which sense the first journal surface, the second journal surface, and a test portion of the outer surface of the shaft, respectively. Each of the surface sensing assemblies has a surface sensor and a transmitter in electrical communication with the surface sensor. The surface sensors continuously sense the radial position of the associated surface of the shaft. During rotation of the shaft, a transmitter of each surface sensing assembly transmits a runout signal proportional to the runout of the associated surface. Each of the runout signals is received by a receiver of a computer. A test operating system, stored in the memory of the computer, applies a normalization program, also stored in the memory, to compute normalized runout data by adjusting the runout signal from the test surface sensing assembly with the runout signals from the first and second journal surface sensing assemblies to factor out deflection of the shaft caused by the standard rest. The test operating system inserts the normalized runout data into predetermined data cells of a runout spreadsheet stored in the memory. Formulas and instructions stored in operator cells of the runout spreadsheet compute and plot the shaft runout.
The system may also comprise a magnetic field sensing device and a plurality of magnets. The magnets are mounted at radially spaced positions on the shaft coupling. A magnetic field sensor of the magnetic field sensing device is positioned proximate to the shaft. A transmitter in electrical communication with the magnetic field sensor transmits an initiation signal each time a one of the magnets passes the magnetic field sensor. In this system, each of the surface sensing assemblies also includes a receiver and the computer also includes a transmitter. The test operating system causes the computer transmitter to transmit a data request signal each time the computer receiver receives a one of the initiation signals and the transmitter of each surface sensing assembly transmitting a discrete runout signal on receipt of a data request signal by the receiver of the surface sensing assembly.
A method for measuring the runout of the shaft described above comprises the steps of attaching the magnets at radially equidistantly spaced points on the shaft coupling. The magnetic field sensor of the magnetic field sensing device is positioned proximate to the shaft coupling such that the magnets are rotatable through a sensing field of the magnetic field sensor with out contacting the magnetic field sensor. The surface sensors of the first and second journal surface sensing assemblies are positioned for sensing the first and second journal surfaces of the shaft, respectively, and the surface sensor of the test surface sensing assembly is positioned for sensing the test surface portion of the shaft. The shaft is rotated, with the surface sensing assemblies continuously sensing the radial position of the associated surface of the shaft and a test run is initiated. Each time a one of the magnets rotates past the magnetic field sensor, an initiation signal is transmitted from the transmitter of the magnetic field sensing device. Each time the transceiver of the computer receives an initiation signal, the computer transmits a data request signal. Each time the transceiver of the surface sensing assembly receives a data request signal, it transmits a discrete runout signal. The computer receives the discrete runout signals and normalizes the runout signal from the test surface sensing assembly to factor out deflection of the shaft caused by the standard rest. The normalized runout signals are then inserted into predetermined data cells of a runout spreadsheet stored in memory of the computer and the runout spreadsheet computes and plots the runout.
It is an object of the invention to provide more efficient systems and methods for measuring the runout of a shaft.
It is also an object of the invention to provide systems and methods for measuring the runout of a shaft which require less operator action and input and are therefore less prone to error.
Other objects and advantages of the invention will become apparent from the drawings and specification.