[Imaging of coronary arteries and measurement of coronary flow using transesophageal Doppler echocardiography: a comparison with transthoracic Doppler echocardiography].

Recent advances in Doppler echocardiographic techniques, especially using transesophageal approach, enable us to observe coronary arteries and their blood flow. However, the advantages of transesophageal approach in the evaluation of coronary artery are indistinct. The aim of this study was to examine the ability of transesophageal Doppler echocardiography (TED) and transthoracic Doppler echocardiography (TTD) to visualize coronary artery and measure its flow. The study population consisted of 17 healthy subjects and 41 patients with heart diseases (arrhythmia in 2, valvular disease in 10, ischemic heart disease without complete or subtotal obstruction of coronary artery in 22, congenital heart disease in two, cardiomyopathy in four, and infective endocarditis in one). Thirty subjects were examined by TED, and 44 subjects were examined by TTD. Two patients with complete obstruction of the proximal right coronary artery (RCA), who were not included in the above-mentioned subjects, were examined by TED. The results were as follows: 1) The detection rate of coronary arteries by TED and TTD were: left main trunk (LMT); 96.7/86.4%, left anterior descending artery (LAD) and left circumflex artery (LCx); 83.3/56.8%, and RCA; 63.3/38.6%, respectively. 2) Visible length from the orifice: LMT to LAD; 22.2/30.8 mm, RCA; 20.4/22.3 mm. 3) The detection rate of coronary flow by pulsed Doppler of the two methods: LMT; 66.8/0%, LAD; 70.0/31.8%, LCx; 6.6/0%. RCA; 26.7/0%. 4) Coronary flow was detected by transesophageal two-dimensional Doppler in 73.3% of LMT, 76.6% of LAD, 6.6% LCx and 43.3% of RCA. 5) RCA flow was not detected by transesophageal two-dimensional Doppler in two patients who had complete obstruction of the proximal RCA although RCA near the orifice was obviously imaged by two-dimensional echocardiography. In conclusion, TED had an advantage over TTD in detecting coronary arteries and their blood flow, but TTD had an advantage over TED as to the visible length of coronary artery. When RCA near the orifice was clearly visualized, the absence of RCA flow by TED implied complete obstruction of the proximal RCA.