Dr. Emmanouil S. Brilakis, Minneapolis Heart Institute and Minneapolis Heart Institute Foundation, Abbott Northwestern Hospital, 920 East 28th Street, #300, Minneapolis, Minnesota 55407.
Obtaining femoral and radial arterial access in the cardiac catheterization laboratory using state-of-the-art techniques is essential to optimize outcomes, patient satisfaction, and procedural efficiency. Although transradial access is increasingly used for coronary angiography and percutaneous coronary intervention, femoral access remains necessary for numerous procedures, many requiring large-bore access, including complex high-risk coronary interventions, structural procedures, and procedures involving mechanical circulatory support. For femoral access, contemporary access techniques should combine the use of fluoroscopy, ultrasound, micropuncture needle, femoral angiography, and vascular closure devices, when feasible. For radial access, ultrasound may reveal important anatomic features and expedite access. Despite randomized controlled trials supporting use of routine ultrasound guidance for femoral and/or radial arterial access, ultrasound remains underused in cardiac catheterization laboratories. This article reviews contemporary techniques to achieve optimal arterial access in the cardiac catheterization laboratory.
Procedural and clinical outcomes for patients presenting to the cardiac catheterization laboratory depend on obtaining safe and adequate vascular access. In addition to routine diagnostic coronary angiography and percutaneous coronary intervention (PCI), arterial access is essential for several other procedures, including structural interventions and percutaneous mechanical circulatory support.
Transradial access has been adopted worldwide and now represents the primary access modality in many countries, with increasing use in the United States (1). Despite the increasing use of transradial access and consequential reciprocal reduction in femoral access use for coronary angiography and PCI, femoral access remains necessary for numerous procedures, many of which require large-bore access. The transfemoral approach is the preferred and most commonly used access for transcatheter aortic valve replacement (2). Femoral access is used in most cases of mechanical circulatory support, such as in the setting of cardiogenic shock, cardiac arrest, or high-risk PCI with such devices as intra-aortic balloon pump, Impella (Abiomed, Danvers, Massachusetts), or venoarterial extracorporeal membrane oxygenation (3). Additionally, femoral access is preferred for some complex coronary interventions, such as coronary chronic total occlusion PCI (4,5).
State-of-the-art arterial access techniques are important for optimizing patient outcomes. This article reviews contemporary techniques to achieve optimal arterial access in the cardiac catheterization laboratory.
Historically, arterial access in the cardiac catheterization laboratory has been obtained using anatomic landmarks along with pulsation and/or fluoroscopic guidance for femoral access (6). Despite wide use outside the cardiac catheterization laboratory for vascular access with guideline recommendations endorsing its use (7), the use of ultrasound in the cardiac catheterization laboratory remains infrequent (8). Point-of-care ultrasound is used across all specialties, with numerous internal medicine residency programs having established formal training curricula nationwide (9).
Few operators, however, use ultrasound routinely for vascular access in the cardiac catheterization laboratory. In a small survey of interventional cardiologists only 13% used ultrasound routinely for femoral access, despite 88% answering that ultrasound was readily available in the cardiac catheterization laboratory, and 90% expressing being comfortable with the technical aspects of ultrasound (8).
Several studies have examined the value of ultrasound-guidance for femoral access (10–13). The largest study was FAUST (Femoral Arterial Access with Ultrasound Trial), a prospective, multicenter trial that randomized 1,004 patients to fluoroscopic- or ultrasound-guided femoral access (10). The rate of common femoral artery cannulation (primary endpoint) was similar with ultrasound and fluoroscopy; however, ultrasound guidance significantly increased common femoral artery sheath placements in patients with high common femoral artery bifurcations (fluoroscopy 69.8% vs. ultrasound 82.6%; p < 0.01). Moreover, ultrasound significantly reduced the number of attempts (3.0 ± 3.2 vs. 1.3 ± 0.9; p < 0.000001), venipuncture (15.8% vs. 2.4%; p < 0.000001), and time to insertion (median 148 vs. 136 s; p = 0.003) and increased first-pass success (46% vs. 83%; p < 0.000001) (10). Similarly, ultrasound guidance reduced clinical access complications (3.4% vs. 1.4%; p = 0.04), a result driven by a significant decrease in hematomas >5 cm (2.2% vs. 0.6%; p = 0.03) (10).
A meta-analysis of randomized controlled trials, involving 1,422 patients showed that compared with palpation, ultrasound guidance was associated with ∼49% reduction in overall complications (relative risk [RR]: 0.51; 95% confidence interval [CI]: 0.28 to 0.90), reduced the rate of venipuncture (RR: 0.18; 95% CI: 0.09 to 0.39) and time to access (mean difference: −25.60 s; 95% CI: −38.11 s to −13.09 s), and increased the likelihood of first-attempt success by ∼42% (RR: 1.42; 95% CI: 1.01 to 2.00) (13).
Numerous studies and meta-analyses have examined the use of ultrasound guidance for radial artery cannulation, with the most recent meta-analysis of 1,992 patients (14), including 2 studies of patients undergoing cardiac catheterization, demonstrating that ultrasound guidance decreased first-attempt failure (RR: 0.68; 95% CI: 0.52 to 0.87; p = 0.03), mean attempts to success (mean difference: −1.26 times; 95% CI: −1.58 to −0.94 times; p < 0.00001), mean time to success (mean difference: −43 s; 95% CI: −80 to −6 s; p = 0.02), and the occurrence of hematoma (RR: 0.39; 95% CI: 0.16 to 0.95; p = 0.04) as compared with traditional palpation.
Several observational studies of patients undergoing cardiac catheterization suggested that routine use of ultrasound for radial access might offer important information to augment procedural success and avoid potential complications (15–17). Baumann and Roberts (15) examined 566 radial and ulnar arteries with ultrasound and reported larger radial and ulnar size in men compared with women (radial: 3.2 vs. 2.7 mm, p < 0.01; ulnar: 2.8 vs. 2.4 mm, p < 0.01); presence of dual radial artery in ∼4% to 5% of patients; and an ulnar artery that was >20% larger than the radial artery in ∼6.5% of patients. This information cannot be obtained by palpation, highlighting how ultrasound may inform selection of the most suitable primary access (15). Similarly, Abazid et al. (16) examined 513 patients undergoing coronary angiography with ultrasound, reporting an association of smaller pre-procedural radial artery diameter, cross-sectional area, and (especially) perimeter with vascular complications.
Could routine use of ultrasound result in lower incidence of radial artery occlusion (RAO) (18,19)? Ultrasound could help assess vessel size and reduce the number of punctures needed for access. Avoiding insertion of sheaths larger than the vessel size reduces the risk of RAO (18,20). In the R-RADAR (Rotterdam Radial Access Research) study, the radial arteries of 90 patients who underwent transradial coronary angiography or intervention were examined with a high-resolution 40-MHz ultrasound before cannulation, 3 h and 30 days after the procedure. More radial puncture attempts were associated with RAO (odds ratio: 3.49; p = 0.022), pulsation loss (odds ratio: 2.64; p = 0.027), and pain or discomfort of the upper extremity (odds ratio: 2.24; p = 0.05) (21).
The largest study of ultrasound guidance for radial access was the RAUST (Radial Artery Access with Ultrasound Trial), a prospective, multicenter randomized controlled trial of 698 patients who were randomized to either palpation or real-time ultrasound guidance (22). The primary endpoints were: 1) number of forward attempts required for access; 2) first-pass success; and 3) time to access (22). In RAUST, ultrasound guidance improved the success and efficiency of radial artery cannulation, reduced the number of attempts (1.65 ± 1.2 vs. 3.05 ± 3.4; p < 0.0001) and time to access (88 ± 78 s vs. 108 ± 112 s; p = 0.006), increased the first-pass success rate (64.8% vs. 43.9%; p < 0.0001), and decreased the number of difficult access procedures (2.4% vs. 18.6% for >5 attempts, p < 0.001; and 3.7% vs. 6.8% for >5 min, p = 0.07) (22). RAUST excluded patients presenting with emergent procedures, where, in the context of hemodynamic instability and difficult-to-palpate pulse, ultrasound may be of even higher value.
Rather than relying on a single approach, contemporary femoral access should ideally be obtained combining all 4 available techniques: 1) fluoroscopy; 2) ultrasound; 3) micropuncture access; and 4) femoral angiography (Central Illustration).
(A) Hemostat to identify lower edge of femoral head. (B) Confirm position of hemostat with fluoroscopy. (C) Ultrasound positioned to visualize common femoral artery (f.a.). (D) Ultrasound visualization of common femoral artery (left) and common femoral artery bifurcation into superficial and profunda (right). (E and F) Triangulation for needle entry. (G) Needle entry position (arrow) and guidewire advancement (Online Video 1) assessed using fluoroscopy. (H) Femoral angiography.
Micropuncture wire advancement under fluoroscopic-guidance.
Few studies examined use of micropuncture needles for arterial access; most were observational, with only 1 completed randomized controlled trial that was terminated prematurely (23–26). Use of a micropuncture needle is appealing because of the small initial arteriotomy size (56% smaller with the 21-gauge micropuncture needle compared with the standard 18-gauge needle) (24). For patients with challenging or ambiguous access, such as those that are obese, those that are anticoagulated, or in the case of a unsatisfactory stick (either too low or high), the use of a micropuncture needle offers a potential benefit because the arteriotomy site is small and hemostasis may be more easily achieved on needle removal (24); however, observational studies have not shown a benefit (25,26). The FEMORIS (Femoral Micropuncture Or Routine Introducer Study) single-center trial randomized 402 patients to 18-gauge standard needle versus 21-gauge micropuncture needle; there was no difference in the primary endpoint (composite of access bleeding); however, the study was underpowered and was terminated prematurely because of withdrawal of funding from the sponsor (23). In several pre-specified subgroups, however, such as women (17.4% vs. 5.8%; p = 0.05), elective nonacute coronary syndrome cases (18.5% vs. 8.6%; p = 0.03) and those with a final sheath size <6-F catheter (15.1% vs. 6.4%; p = 0.02), the 21-gauge micropuncture needle was associated with lower rates of bleeding (23). In an observational study of patients undergoing standard access with the 18-gauge needle and a 0.035-inch wire (n = 2,699) versus micropuncture access with the 21-gauge needle (n = 544), Ben-Dor et al. (26) demonstrated no significant difference in overall access site complication rates. However, the frequency of retroperitoneal hemorrhage was slightly higher in the micropuncture group (0.7% [n = 4] vs. 0.18% [n = 5]; p = 0.04), suggesting that guidewire advancement should be performed under fluoroscopy to prevent inadvertent wiring of side-branches (26) (Online Video 1). Given the lack of robust data supporting the use of micropuncture, use of standard 18-gauge needles is acceptable. An echogenic tip needle can be used to facilitate needle-entry visualization.
In a study of consecutive femoral angiograms (n = 200) the common femoral artery bifurcation was at or below the center of the femoral head in 98.5% of cases (27), highlighting the value of routine fluoroscopic guidance. Combining fluoroscopy and ultrasound guidance and micropuncture needle may offer the best results by optimizing access location and minimizing the risk of femoral artery injury (Central Illustration).
Puncture below the common femoral artery bifurcation can result in pseudoaneurysm formation. Ultrasound readily identifies patients with a high common femoral artery bifurcation (∼5% of the FAUST trial patients had their bifurcation at the level of upper or middle third of the femoral head) (28). Awareness of the common femoral artery bifurcation location allows operators to choose: 1) obtaining high access above the bifurcation (Figure 1); 2) intentionally accessing the superficial femoral artery; or 3) using of the contralateral femoral artery (although the likelihood of high bifurcation in the contralateral femoral artery is high) (29). Although the classic teaching is to obtain common femoral access this must be balanced against the risk of bleeding with higher punctures. Therefore, in patients with high common femoral artery bifurcation some operators pursue superficial femoral artery access taking into account the higher risk for pseudoaneurysm formation. The latter might be decreased by using a closure device (30,31). Ultrasound can also help identify other features that may inform on optimal access site, such as femoral calcification (Figure 2) or the relationship to the femoral head (Figure 3).
(A) The lower edge of the femoral head is identified using fluoroscopy and the site marked on the skin using a hemostat. Ultrasound is used to visualize the common femoral artery. Needle entry position (arrow) is assessed in relationship to the femoral head using fluoroscopy (B). Femoral angiography is performed showing successful common femoral arterial access (C).
Common femoral artery calcification on ultrasound (arrows).
Transverse ultrasound image of the femoral artery in relationship to the femoral head (arrow) and its course change (diving into the pelvis) above the femoral head (star).
For optimal results we recommend obtaining femoral access as follows (Central Illustration). First, the lower edge of the femoral head is identified using fluoroscopy and its position marked on the skin using a hemostat (Central Illustration, A and B). Marking this position at the skin with a sterile marker as a landmark for scanning with the ultrasound probe is helpful. Second, the ultrasound probe is positioned above this line on top of the femoral head to visualize the common femoral artery (Central Illustration, C and D). Scanning is performed proximally and distally to identify the bifurcation of the common femoral artery into superficial and profunda femoral arteries (Central Illustration, D). Third, subcutaneous local anesthetic is injected with live ultrasound visualization. Fourth, under ultrasound guidance, micropuncture needle is inserted (aiming to only puncture the anterior wall) approximately 1 to 3 cm below the ultrasound probe with the purpose of triangulating the optimal position at which the needle path can be visualized entering the common femoral artery (Central Illustration, E and F). The latter step is the most challenging for beginners, with potential mistakes including changing the ultrasound position on the skin or beam angle, potentially leading to high femoral access. The closer the needle entry point is in the skin to the ultrasound probe, the steeper the angle required on the needle to triangulate the position, and vice versa (Central Illustration, E and F). If the puncture aim is the artery, but the vein is accessed instead, the vein should not be cannulated to avoid an arteriovenous fistula, especially if using a through-and-through technique. Fifth, once arterial access is obtained and confirmed by visualizing brisk arterial blood flow from the needle exit point, the guidewire is advanced (and stopped immediately if any resistance is felt). If using micropuncture, the wire should be advanced a short distance to gain position in the vessel’s lumen, with subsequent advancement performed under fluoroscopic-guidance (Online Video 1). An advantage of using micropuncture is that the operator may visualize the entry site of the needle in relation to the femoral head (with the goal being achieving needle entry position preferably at or below the center of the femoral head, Central Illustration, G). If the entry position is unsatisfactory the small-caliber needle can be removed, manual pressure can be briefly applied for hemostasis, and access reattempted before proceeding with sheath insertion. Once optimal wire position is achieved, a 4-F catheter sheath is advanced over-the-wire when using micropuncture, transitioning to the intended femoral sheath (6-F to 8-F catheter being the most commonly used sheath sizes for coronary angiography and/or PCI). Once the sheath is inserted, femoral angiography should be routinely performed (except possibly in cases of advanced kidney disease) ideally at a 30° ipsilateral angulation to optimize the view of the artery and the puncture before coronary angiography is performed (Central Illustration, H). If bleeding is detected, PCI should be deferred because heparin administration could exacerbate bleeding.
Although infrequent, potential challenges exist when using the contemporary access techniques described previously. For example, using ultrasound, optimal visualization is sometimes challenging in the morbidly obese or those with calcification. Similarly, in the obese patient, contrary to the more supportive J-wire used with the standard 18-G needle, the micropuncture access technique involves a smaller sheath and guidewire that can kink.
A comprehensive review of arterial closure devices (32,33) is beyond the scope of this article. However, vascular closure devices should be used, whenever possible, at the end of the procedure to achieve faster hemostasis, shorter duration of bed rest, and improve patient comfort (32). Obtaining femoral access as described previously increases the likelihood of using a closure device, by enabling access below the inferior epigastric artery and above the femoral artery bifurcation, in an adequate caliber common femoral artery that is free from atherosclerosis at the puncture site, features identified by femoral angiography and/or ultrasound.
For radial access, whether the first step should be to demonstrate the permeability of the ulnopalmar arch patency or not remains a matter of debate, with many operators not performing such testing based on the findings from the RADAR (Predictive Value of Allen’s Test Result in Elective Patients Undergoing Coronary Catheterization Through Radial Approach) study (34). RADAR enrolled 203 patients, 60 (30%) of whom had an abnormal Allen test, but no clinical or subclinical signs of hand ischemia were identified. Similarly, in the MATRIX (Minimizing Adverse Haemorrhagic Events by Transradial Access Site and Systemic Implementation of angioX) randomized trial, which assessed the patency of the ulnopalmar arches after randomization using the modified Allen and Barbeau tests, no major ischemic complications were observed (35,36).
Whether routine ultrasound guidance is better than palpation alone remains controversial, although randomized data have demonstrated that ultrasound guidance improves the success and efficiency of radial artery cannulation (22). The technique for gaining radial access using ultrasound (37) involves minimum depth of ultrasound penetration to maximize visualization (Figure 4, Online Video 2). The ultrasound probe is positioned approximately 1 to 2 cm proximal to the radial styloid process. Local anesthetic is injected with or without ultrasound guidance (only 1 to 2 ml are administered to avoid distorting the anatomy).
Radial artery ultrasound (Online Video 2).
Ultrasound-guided radial access using the through-and-through technique.
Access may be obtained using 2 distinct techniques: an anterior wall or a through-and-through puncture (33). Using the anterior wall puncture technique, a short micropuncture needle enters the radial artery lumen with immediate visualization of arterial blood flow exiting the needle and subsequent wiring of the vessel with a steel wire. Alternatively, using the through-and-through technique with a catheter-over-needle system (the through-and-through technique can also be performed using a short micropuncture needle), the needle punctures the anterior wall first, at which point blood fills the proximal hub (in some cases one may successfully puncture the artery as confirmed on ultrasound, yet the hub does not fill with blood) and the needle and catheter are further advanced to puncture the posterior wall. The needle is removed and the catheter is gradually withdrawn until pulsatile arterial blood flow is seen and the vessel wired with a 0.021-inch guidewire. The guidewire is rotated on advancement to avoid side branches. Both techniques were compared in a randomized trial of 412 patients undergoing transradial catheterization (without the use of ultrasound), in which the incidence of hematoma and 30-day RAO did not differ between approaches; however, the through-and-through technique was associated with faster access and procedural time, lower number of attempts, and faster first-attempt access (38).
Once radial access is obtained, a regular or polymer-jacketed (e.g., the Glidewire Baby-J, Terumo Medical Corporation, Somerset, New Jersey) J-wire is advanced to the ascending aorta followed by the diagnostic or guide catheter. Fluoroscopy should be used if any resistance is felt, particularly when navigating calcified and/or tortuous subclavian junctions.
In contrast to femoral access, radial hemostasis consists of compressive bandages or devices that mimic manual compression (33). The goal of these devices, in addition to obtaining hemostasis, is to prevent RAO by performing nonocclusive “patent” hemostasis (39).
▪ Ultrasound guidance should be routinely used to obtain vascular access, especially femoral access.
▪ All cardiac catheterization laboratories should have ultrasound available to guide vascular access. Interventional societies should promote the use of ultrasound for vascular access.
▪ General cardiology and interventional training programs, including structural and CHIP (complex, high-risk, indicated procedures) subspecialty training programs, should facilitate trainee proficiency in both radial and femoral arterial access and use of ultrasound guidance.
▪ RAO is a limitation of radial catheterization. Whether routine use of ultrasound leads to lower RAO rates compared with blind radial access requires further study.
▪ Most studies examining the use of ultrasound have demonstrated a benefit in patients undergoing elective procedures. RAUST excluded patients undergoing emergent procedures and FAUST excluded patients with ST-segment elevation myocardial infarction or unstable non-ST-segment elevation myocardial infarction. However, in patients with difficult to palpate pulses, hypotension, cardiac arrest, or ongoing resuscitation the value of ultrasound may be even greater.
▪ Studies comparing radial with femoral access using contemporary techniques mandating the complementary routine use of fluoroscopy, ultrasound guidance, micropuncture needle, femoral angiography, and closure devices are needed (40–42).
▪ Patients undergoing procedures requiring large-bore access may benefit even more from contemporary femoral access techniques, especially with the use of ultrasound guidance, but further study is needed.
Transradial access has been adopted worldwide and now represents the primary access modality in many countries, with increasing use in the United States. Use of transradial access improves patient comfort overall and improves outcomes in patients with ST-segment elevation myocardial infarction. Femoral access, however, remains necessary for numerous procedures that require large-bore access, including complex high-risk coronary interventions, structural procedures, and mechanical circulatory support. Contemporary, state-of-the-art femoral access is obtained using fluoroscopy, ultrasound guidance, micropuncture needles, femoral angiography, and use of arterial closure devices. Contemporary arterial access could significantly improve the safety of the procedure and requires additional study and education, especially of trainees and early career interventionalists.
Dr. Brilakis has received consulting/speaker honoraria from Abbott Vascular, Amgen, Asahi, Cardiovascular Systems Inc., Elsevier, GE Healthcare, and Medicure; research support from Boston Scientific and Osprey; and his spouse was an employee of Medtronic. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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