IMPROVED DOPPLER DETECTION OF PROXIMAL LEFT ANTERIOR DESCENDING CORONARY-ARTERY STENOSIS AFTER INTRAVENOUS-INJECTION OF A LUNG-CROSSING CONTRAST AGENT - A TRANSESOPHAGEAL DOPPLER-ECHOCARDIOGRAPHIC STUDY

Objective. This study was designed to verify the usefulness of transes ophageal Doppler recording of blood flow velocity in the proximal left anterior descending coronary artery, after a peripheral injection of a lung-crossing contrast agent (SHU 508A), in detecting and locating a hemodynamically significant stenosis (vessel narrowing greater than o r equal to 50%) affecting this portion of the vessel. Background. Tran sesophageal Doppler echocardiography has a limited diagnostic impact o n the evaluation of proximal left anterior descending coronary artery stenoses. Peripheral injection of SHU 508A, a lung-crossing contrast a gent enhancing Doppler signal to noise ratio in coronary arteries, may allow recording of localized disturbed blood how velocity at the sten osis site even in the absence of a clear B-mode visualization of the v essel. Methods. Transesophageal Doppler echocardiography, before and a fter echo contrast injection, was performed in 31 patients who underwe nt coronary angiography. Using color Doppler as a guide, pulsed wave D oppler recording of blood flow velocity in the left anterior descendin g coronary artery was attempted to detect a localized increase in bloo d flow velocity. B-mode evaluation of the vessel was also performed. R esults. Angiography showed a significant proximal left anterior descen ding coronary artery stenosis in 16 patients (group 1) and no stenosis in 15 patients (group 2). In 15 of 16 group 1 patients, Doppler after contrast injection revealed a localized velocity increase of at least 50% of the reference value; mean (+/-SD) percent increase in velocity was 150 +/- 89% (range 367% to 0%). In group 2 Doppler after contrast injection revealed a mild localized increase in velocity in four pati ents and no increase in velocity in the remaining 11 patients; mean (/-SD) percent increase in velocity was 5 +/- 7% (range 21% to 0%, p +/ - 0.001 vs. percent increase in group 1). When a percent velocity incr ease greater than or equal to 50% of the reference value was considere d a positive criterion for detecting significant stenosis, the sensiti vity and specificity were 92% and 100%, respectively. The sensitivity of the evaluation before contrast injection or considering B-mode imag ing alone was much lower (25% and 19%, respectively, p < 0.001 vs. eva luation after contrast injection). In addition, color Doppler after co ntrast injection correctly located the stenosis along the vessel, as c ompared with angiography. Conclusions. Blood how evaluation of the pro ximal left anterior descending coronary artery by transesophageal Dopp ler echocardiography after contrast injection is a feasible and reliab le method for detecting and locating significant stenoses affecting th is part of the vessel and is an improvement over the traditional ultra sound approach.