Detection, location, and severity assessment of left anterior descending coronary artery stenoses by means of contrast-enhanced transthoracic harmonic echo Doppler.

Aims: Contrast-enhanced second harmonic Doppler (ED) is a new ultrasound modality that increases the feasibility of recording blood flow velocity (BFV) in the left anterior descending coronary artery (LAD) using a transthoracic approach. Blood flow velocity convective acceleration is a reliable marker of coronary stenosis and can be used to assess the percentage area reduction at the stenosis site by applying the continuity equation. To detect, locate, and assess the severity of significant stenosis throughout the LAD by means of an ED recording of BFV acceleration at the stenosis site.
Methods and Results: Fifty-three consecutive patients undergoing coronary angiography (CA) underwent a colour-guided pulsed-wave ED recording of BFV in the proximal/mid and distal portions of the LAD, and maximal and reference BFV was obtained in each of the two arterial segments. Maximal velocity was much higher in the diseased segments (>or=50% lumen narrowing) than in the normal segments (143 +/- 84 vs. 38 +/- 20 cm/s; P < 0.001); as the reference velocity was similar (37 +/- 13 vs. 31 +/- 12; P = 0.03), the percentage increase in velocity was also higher (290 +/- 233 vs. 20 +/- 37%; P < 0.001). Using a cut-off value of an 82% increase in velocity, sensitivity and specificity vs. CA was, respectively, 86 and 95%. The reduction in the percentage area of stenosis calculated using the continuity equation agreed with that determined by means of quantitative CA (r = 0.7).
Conclusion: Blood flow velocity evaluation in the LAD by means of transthoracic ED is feasible and reliable in detecting, locating, and assessing the severity of LAD stenosis.