Evaluation of Coronary Flow Reserve by Transesophageal Doppler Echocardiography in Patients with Chest Pain and Normal Coronary Angiogram

Youn, Ho Joong; Chung, Wook Sung; Kim, Jong Jin; Park, Joon Chul; Kim, Chul Min; Chae, Jang Seong; Park, In Soo; Kim, Jae Hyung; Choi, Kyu Bo; Hong, Soon Jo

Abstract

BACKGROUND
The measurement of coronary flow reserve(CFR) is essential for assessing the flow capacity in patients with angina and normal coronary angiogram. Transesophageal Doppler echocardiography(TEE) is a noninvasive method of assessing coronary flow velocity in the proximal portion of left anterior descending coronary artery. This study was designed prospectively to evaluate the usefulness of measurement of CFR by TEE in patients with chest pain and normal coronary angiogram.
METHODS
We studied 49 subjects with chest pain and normal coronary angiogram. Exercise treadmil test by Bruce's protocol was positive in 26 subjects (TMT+group, M : F=8 : 18, mean age 55+/-8) and negative in 23 subjects (TMT-group, M : F=7 : 16, mean age 50+/-12). None of these subjects had previous history of myocardial infarction, atrial fibrillation, significant valvular heart disease, variant angina, wall motion abnormality on ventriculogram and ejection fraction below 50%. After transthoracic echocardiography(H-P Sonos 1000, 2.5 MHz), peak diastolic(PDV) and peak systolic coronary flow velocity(PSV) of proximal portion of left anterior descending coroanry artery by TEE(H-P Sonos 1000, 5 MHz, Single plane) were obtained in resting condition, 4 and 6 minutes after dipyridamole injection(DPY, 0.56mg/kg i.v.), and 2 minutes after aminophyline injection(100mg i.v.). CFR was computed as ratio of the average PDV after DPY to resting PDV.
RESULTS
1) TMT(+) group showed higher incidence of history of typical angina and greater wall thickness than TMT(-) group(P < 0.005). 2) The PDV, PSV and PDV/PSV ratio were significantly increased 6min after DPY IV in both groups as compared to rest(P < 0.05) and decreased to previous level after APL IV. 3) There was no significant difference in double products between rest and DPY IV. 4) CFR was significantly greater in TMT(-) group than in TMT(+) group(P < 0.0005).
CONCLUSIONS
TEE using DPY is a useful noninvasive method to evaluate the coronary flow reserve in patients with chest pain and normal coronary angiogram. The influences of physiologic variables in measuring CFR by TEE should be investigated further.