a 75-year - old , 155 cm , 53 kg female patient presented for off - pump coronary artery bypass graft surgery . as a preoperative test the results revealed 86% stenosis of the left anterior descending artery , 83% stenosis of the left circumflex artery and 91% stenosis of the right coronary artery . the aortography revealed that only the right common carotid artery was aberrant in the aortic arch . 1 ) , but delayed imaging of the right subclavian artery was observed ( fig . 2 ) . ecg and other tests did not reveal other abnormal findings and there were no symptoms of dysphagia or respiratory difficulty . the patient was pre - operatively administered 6 mg of morphine by muscular injection , was after which she was moved to the operating room . the pulses of both radial arteries were palpated well and there was no difference in blood pressure between the two upper extremities . because the left radial artery was going to be used as the graft vessel , a 20-gauge catheter was inserted into the right radial artery , and continuous monitoring of the arterial pressure was initiated . a pulmonary artery catheter was inserted into the right internal jugular vein to monitor cardiac performance parameters continuously . to induce anesthesia , 50 g sufentanil , 2.5 mg midazolam , and 10 mg vecuronium were administered and endotracheal intubation was performed . anesthesia was then maintained using a continuous sufentanil infusion ( 0.5 - 1.5 g / kg / hr ) and supplemental sevoflurane ( 0.6 - 2.0 vol% ) . next , a 20-gauge catheter was inserted into the right femoral artery to enable accurate blood pressure monitoring . the radial artery pressure was monitored along with the continuous monitoring of the femoral artery pressure . hemodynamic conditions following the induction of anesthesia were stable , and a 14  12.5 mm tee probe ( 6 t probe , ge vingmed ultrasound , horten , norway ) was inserted into the patient 's esophagus . immediately after insertion of the tee probe , the arterial pressure waveforms of the right radial artery decreased significantly , whereas the right femoral artery pressure remained stable . the tee probe was slowly removed from the patient 's esophagus , after which the right radial waveform reappeared 28 cm from the upper incisor . after slowly advancing and retracting the probe twice , we observed the dampening of arterial pressure reoccur ( fig . it was suspected that the tee probe caused compression of the right subclavian artery ; therefore , the tee probe was removed . diluted blood was observed on the tip of the tee probe after it was removed , indicating that the esophagus may have been damaged by the probe . accordingly , a physician immediately conducted an esophageal endoscopy , which revealed an esophageal stenosis following pulsation on the posterior esophageal wall . with the use of the scope , we found the location of the stenosis to be 28 cm from the upper incisor , but no damage to the esophageal wall was observed . a 9.0  9.0 mm gastroscope ( gif - xq260 , olympus medical system co. , tokyo , japan ) was used for esophageal endoscopy and easily passed through the area of the stenosis . no compression of the right subclavian artery was observed ; therefore , we inserted a 10.9  8.4 mm pediatric tee probe ( 9 t probe , ge vingmed ultrasound , horten , norway ) and proceeded with the surgery . we experienced compression of the right subclavian artery caused by the tee in an adult patient who had a vascular ring . vascular rings are a rare congenital anomaly in which the fetal structure of the aortic arch persists . vascular rings account for less than 1% of all cardiopulmonary mutations and are grouped based on their anatomical characteristics . the most common type of complete ring is a double aortic arch , which consists of two arches that connect posteriorly and form a vascular ring . a right aortic arch and right subclavian artery that is retropharyngeal with a left - sided ductus arteriosus is the next most common types of vascular rings . the most common incomplete rings are a retropharyngeal right subclavian artery , innominate artery compression , and a pulmonary artery sling . however , ecg and other tests can not detect these symptoms ; therefore , they often exist without the patient 's knowing of their presence [ 4 - 7 ] . the patient in the present case had a right subclavian artery that was aberrant in the descending aorta of the distal portion of the left subclavian artery and passed between the esophagus and the vertebral body . in most cases , such variations do not present abnormal findings , and the patient in this case also had no symptoms prior to surgery . tees have increasingly been used for anesthetic management in cardiac and noncardiac surgeries for patients with cardiac defects and other hemodynamic problems . serious complications such as esophageal perforation , respiratory obstruction and ventilator failure may occur ; however , such phenomena are rare . there have been reports of patients with vascular rings in which the tee probe caused vascular compression , but these cases involved babies or young children for whom the probe was larger than their body surface area . there are currently no other known cases of an adult who had the same complications as the patient described in the present case . it is important to emphasize in this case that obstruction of the right subclavian artery for a long period of time can lead to ischemic damage and necrosis . when tee is used for monitoring during surgery , as in the present case , if obstruction of the artery is not discovered early , the probe may cause vascular compression for a long period of time . mechanical damage to the narrowed esophageal mucous membrane by the tee probe can lead to hemorrhage , laceration , or perforation . therefore , if resistance is felt when the tee probe is inserted in patients with congenital anomalies one must refrain from inserting the probe by force . after insertion , it is necessary to compare the blood pressure of both upper extremities or to continuously monitor the other subclavian artery pressure or femoral artery pressure . here , we presented a case of occlusion of the right subclavian artery by a tee probe in an adult patient with a vascular ring . cases of vascular compression by the tee probe in patients with vascular rings are rarer for adults than for children ; nevertheless , they do occur in adults . accordingly , careful attention must be taken with respect to monitoring methods and operative techniques when using a tee probe .
intraoperative transesophageal echocardiography ( tee ) has become an important monitoring device for patients undergoing cardiac or noncardiac surgery . 
 complications associated with tee are unusual , but the potential for tee probe compression of the posterior vascular structures has been reported in pediatric patients . 
 we present here a case of occlusion of the right subclavian artery in an adult patient with a vascular ring after insertion of a tee probe .