Dobutamine echocardiography and myocardial contrast echocardiography. Two new techniques for the assessment of myocardial viability.

As investigators have discovered that cardiac regions displaying resting wall motion abnormalities are not the necessary equivalent of myocardial scar (and therefore of irreversible injury) but are potentially viable regions rendered dysfunctional by stunning or hibernation, a new field of medicine has developed to identify viable myocardium that can improve in function after revascularization. Moreover, improvements in myocardial preservation and perfusion during coronary artery bypass grafting and percutaneous transluminal coronary angioplasty have enabled patients with poor resting ejection fractions to undergo safer revascularization. In this review, we describe briefly the diagnostic techniques most commonly used in identifying dysfunctional but viable myocardium. We give specific attention to the assets and limitations of these techniques and special emphasis to 2 promising new techniques: dobutamine echocardiography and myocardial contrast echocardiography.