Measurement of Coronary Flow Velocity by Transesophageal Doppler Echocardiography: Preliminary Study for Clinical Application

Background

The estimation of coronary flow velocity(CFV) is essential for assessing the impaired coronary flow reserve in patients whith angina pectoris and normal coronary arteries. But, intracoronary blood flow velocity measurement remains invasive,requiring cardiac catheterization and can not be repeated without risk during serial follow-up study. Transesophageal Doppler echocardiography(TEE) is a new noninvasive method of assessing CFV in the proximal portion of left anterior descending coronary artery. This study was performed to clarify the value of TEE in evaluating CFV, to compare the coronary flow patterns among various cardiac diseases, to estimate the coronary flow dynamics according to change of blood pressure, and to evaluate the parameters influencing CFV.

Methods

We studied 95 subjects, 51 men and 44 women, mean age 46. Normotensive subjects were 29, hypertensive patients 41, aortic stenosis 5, aortic regurgitation 4, mitral stenosis 8, and others 8. After transthoracic echocardiography(H-P Sonos 1000,2.5 MHz), transesophageal echocardiography was performed using a 5-Hz(omniplane)transesophageal probe connected to a H-P Sonos 1000 to assess CFV in the proximal portion of left anterior descending coronary artery. Doppler evaluation of left anterior descending coronary blood flow velocity was obtained in restiong conditions and after sublingual administraion of nitroglycerim(0.6mg), Blook pressure and heart rate were monitored thoughout the entire procedure.

Results

1) The detection rate of CFV by TEE was 89.5%.

2) The morphology of CFV in proximal left anterior descending coronary artery was biphasic(greater diastolic and smaller systolic).

3) The baseline CFV in hypertensive patients was greater than in normotensive subjects(p<0.05) but there was no difference between two groups in diastolic/systolic CFV ratio.

4) The diastolic CFV and diastolic/systolic CFV ratio in patients with aortic stenosis were greater than in normotensive subjects(p<0.05).

5) The CFV was significantly decreased after administration of nitroglycerin(p<0.05) and the decrement of CFV correlated closely with the decrement of systolic(r=0.65, p<0.05) and diastolic blood pressure(r=0.57, p<0.05).

6) Major parameters influencing CFV were systolic blood pressure and heart rate.

Conclusion

The CFV is influenced by various parameters and the TEE may be a useful, noninvasive tool to investigate the coronary flow dynamics.