Transthoracic Doppler echocardiography - noninvasive diagnostic window for coronary flow reserve assessment

Abstract

This review focuses on transthoracic Doppler echocardiography as noninvasive method used to assess coronary flow reserve (CFR) in a wide spectrum of clinical settings. Transthoracic Doppler echocardiography is rapidly gaining appreciation as popular tool to measure CFR both in stenosed and normal epicardial coronary arteries (predominantly in left anterior descending coronary artery). Post-stenotic CFR measurement is helpful in: functional assessment of moderate stenosis, detection of significant or critical stenosis, monitoring of restenosis after revascularization. In the absence of stenosis in the epicardial coronary artery, decreased CFR enable to detect impaired microvascular vasodilatation in: reperfused myocardial infarct, arterial hypertension with or without left ventricular hypertrophy, diabetes mellitus, hypercholesterolemia, syndrome X, hypertrophic cardiomyopathy. In these diseases, noninvasive transthoracic Doppler echocardiography allows for serial CFR evaluations to explore the effect of various pharmacological therapies.

Figure 1

Left main stem coronary artery and proximal segment of LAD in color-coded transthoracic Doppler echocardiography.

Figure 2

Spectral Doppler coronary blood flow by sampling in proximal segment of LAD.

Figure 3

Direct visualization of coronary artery stenosis. The portion of mid segment of LAD with color mosaic (a sign of high-velocity, turbulent flow) at stenotic site.