Myocardial contrast echocardiography: a new tool in the noninvasive assessment of perfusion

Although the ability to visualize the microvascular circulation by injection of microbubbles has been recognized for over 30 years, only recently the considerable progress in both ultrasound techniques and new contrast media has made myocardial contrast echocardiography a reliable, noninvasive method for the assessment of regional myocardial perfusion. Several clinical studies have validated this technique for the identification of resting myocardial perfusion defects after myocardial infarction and the detection of no-reflow in ischemia-reperfusion model. In addition, preliminary studies have shown the ability of this method to recognize regional myocardial ischemia during pharmacological stress tests in known or suspected coronary artery disease. Finally, in the experimental setting, the estimation of different degrees of severity of coronary artery stenosis has been proposed using the quantitative assessment of myocardial perfusion by time-intensity curves. Although to date some unresolved questions hinder the routine clinical application of this novel noninvasive technique, myocardial contrast echocardiography is close to providing significant advances in the ultimate goal of any cardiac imaging technique, i.e. the simultaneous assessment of both perfusion and function.