[Assessment of perfusion defects by intracoronary myocardial contrast echocardiography]

Myocardial contrast echocardiography has developed rapidly in the last few years. This paper is a review of this method based on our previous studies performed in 43 closed chest dogs. An injection of 2 ml of an agitated saline-Renografin mixture into the left main coronary artery provided contrast opacification of the entire circumference of the left ventricular myocardium. Contrast injection into the left anterior descending or the circumflex artery resulted in contrast opacification of localized regions of the left ventricle. Contrast injection into the left main coronary artery after a selective coronary artery occlusion resulted in a "negative" contrast outline of the corresponding area indicating the underperfused myocardium. The physiological and hemodynamic effects of the intracoronary injection of the contrast material appeared minor and brief. Perfusion defects after coronary artery occlusion assessed by myocardial contrast echo correlated well with those in equivalent sections by monastral blue dye injected into the left ventricle. Furthermore, the extent of myocardial necrosis after five hours of coronary occlusion assessed by myocardial contrast echo correlated well with the area of necrotic myocardium in equivocal slabs. Myocardial contrast washout index (T1/2) measured by digital intensity analysis of successive end-diastolic images was found to be significantly changed in dogs with varying degrees of coronary stenosis. Thus, the measurement of T1/2 appears to be feasible for evaluating degree of coronary stenosis, however, numerous technical problems remain to be clarified.