Quantitative parameters of myocardial perfusion with contrast echocardiography in human beings: Influence of triggering mode

Vascular lesions and s-thrombomodulin concentrations from auricular arteries of rabbits infused with microbubble contrast agent and exposed to pulsed ultrasound

Arterial injury resulting from the interaction of contrast agent (CA) with ultrasound (US) was studied in rabbit auricular arteries and assessed by histopathologic evaluation and s-thrombomodulin concentrations. Three sites on each artery were exposed (2.8 MHz, 5-min exposure duration, 10-Hz pulse repetition frequency, 1.4-mus pulse duration) using one of three in situ peak rarefactional pressures (0.85, 3.9 or 9.5 MPa). Saline, saline/CA, and saline/US infusion groups (n = 28) did not have histopathologic damage. The saline/CA/US infusion group (n = 10) at exposure conditions below the FDA mechanical index limit of 1.9 did not have histopathologic damage, whereas the saline/CA/US infusion group (n = 9) at exposure conditions above the FDA limit did have damage (5 of 9 arteries). Lesions were characteristic of acute coagulative necrosis. Mean s-thrombomodulin concentrations, a marker for endothelial cell injury, were highest in rabbits exposed to US at 0.85 and 3.9 MPa, suggesting that vascular injury may be physiological and not accompanied by irreversible cellular injury.

Potential clinical applications of myocardial contrast echocardiography in evaluating myocardial perfusion in coronary artery disease

Myocardial contrast echocardiography (MCE) is a relatively new technique that uses microbubbles to produce myocardial opacification. Recent advances in echocardiography have resulted in improved detection of microbubbles within the myocardium allowing combined acquisition of function and perfusion data, thus making MCE suitable for bedside use. Regardless of the imaging modality chosen or the type of stress used, MCE detects changes developing in the coronary microcirculation, providing important information for the evaluation of severity of coronary artery disease and for the detection of viable myocardial tissue in acute or chronic coronary artery disease.

Prediction of functional recovery of hibernating myocardium using harmonic power Doppler imaging and dobutamine stress echocardiography in patients with coronary artery disease

The aim of this study was to compare the accuracy of harmonic power Doppler imaging (HPDI) and dobutamine stress echocardiography (DSE) in predicting recovery of myocardial function after bypass surgery. HPDI using triggering imaging with the administration of Levovist (Shering AG, Berlin, Germany) and DSE were performed in 34 patients (mean age 64 +/- 5 years) with left ventricular dysfunction. A repeat echocardiogram at rest was performed 3 months after revascularization. Of the 408 revascularized dysfunctional segments, 188 (45%) improved on the repeat echocardiogram. HPDI exhibited overall similar sensitivity (88% vs 87%) and accuracy (74% vs 79%) but lower specificity (61% vs 72%, p<0.05) compared with DSE for predicting recovery of myocardial function. Only delayed opacification at the 1:8 triggering point, demonstrated in 62% of viable segments, exhibited higher sensitivity (63%) and positive (58%) and negative (66%) predictive values than early opacification at 1:4 (25%, p<0.001; 35%, p<0.001; and 49%, p<0.001, respectively) in predicting functional recovery. The presence of contrast enhancement within the revascularized area resulted in a significant improvement after revascularization in wall motion score index and ejection fraction compared with areas with residual contrast defect (1.9 +/- 0.3 vs 2.3 +/- 0.3, p<0.01; 36 +/- 6% vs 29 +/- 5%, p<0.01, respectively). Significant correlations were observed between the contrast score index and the follow-up wall motion score index (r = -0.67) and between the contrast score index and the follow-up ejection fraction change (r = 0.65). Triggered HPDI has high sensitivity in detecting hibernating myocardium and can accurately predict the potential for recovery of ischemic left ventricular dysfunction 3 months after revascularization.