DOBUTAMINE STRESS ECHOCARDIOGRAPHY - DIAGNOSTIC UTILITY

Pharmacologic stress testing is an accepted alternative in those patients unable to perform exercise stress testing. The most prevalent form of pharmacologic stress testing remains thallium imaging during vasodilator stress with either dipyridamole or adenosine infusions. More recently, dobutamine stress echocardiography has emerged as a promising new technique for the evaluation of patients with known or suspected coronary disease. The rationale for the use of dobutamine infusion as a stress agent lies in its ability to simulate physical exercise through its beta-receptor agonist activity. This causes a supply-demand mismatch which in turn, creates regional myocardial dysfunction which can be detected by two-dimensional echocardiography. A major advantage in the use of echocardiography over other adjunctive imaging techniques is its ability to detect all forms of anatomic heart disease which may be associated with chest pain or may mimic ischemic chest pain. Our current dobutamine protocol involves stepwise infusion of dobutamine beginning at 5-mu-g/kg/min and increasing to 10, 20, and a peak of 30-mu-g/kg/min in three minute stages. Images are recorded in standard parasternal long axis and short axis, four chamber and two chamber views, digitized and displayed for comparison in a quad screen format. A 16 segment model is used for scoring wall motion abnormalities. Ischemia is considered present when a wall motion abnormality develops in an area with normal or only hypokinetic resting wall motion. The overall accuracy is between 85 and 90% for the detection of patients with coronary disease. In over 600 studies at our institution, no major side effects or complications have occurred. Presently, the most intense interest in dobutamine stress echocardiography is in the evaluation of patients with chest pain syndromes, but preliminary studies show promise in the areas of prognosis post myocardial infarction, in preoperative risk stratification, and in predicting myocardial viability following an ischemic insult. Clinical studies in these areas are currently underway.