Use of dobutamine stress echocardiography in determination of myocardial viability

Echocardiography is a versatile, accurate and readily available method for the evaluation of cardiac anatomy and function. Used in conjunction with exercise or pharmacological stress protocols, modern 2-dimensional echocardiographic techniques can readily assess regional, as well as global, left ventricular (LV) function, and provide information regarding the presence, severity and distribution of coronary artery disease (CAD). In contrast to the coronary vasodilators adenosine and dipyridamole, dobutamine infusion simulates exercise by raising myocardial oxygen consumption through its inotropic and chronotropic effects. Dobutamine is a beta 1 receptor agonist that exerts positive inotropic activity without significant alpha or beta 2 effect. This results in little effect on peripheral vascular tone and considerably less chronotropic and arrhythmogenic activity than dopamine, norepinephrine or isoproterenol. Ischemic end-points during DSE include the development of abnormalities in regional wall motion or thickening of previously normal segments or worsening in areas of baseline hypokinesis. Augmentation of wall motion in hypokinetic segments has been reported by several studies during low-dose dobutamine infusion and has been suggested as a marker of myocardial viability.