Non-Invasive Monitoring of Hemodynamic Changes During Dobutamine Stress Echocardiographic Testing Using Impedance Cardiography (ICG)
Dobutamine stress echocardiography is valuable as an alternative stress imaging test for evaluation of Coronary Artery disease in patients who are unable to perform standard treadmill or bicycle exercise (1). Dobutamine induced wall motion abnormalities within the myocardium supplied by a stenosed coronary artery are thought to be provoked by increasing external cardiac work and therefore oxygen demand (2). The increments in heart rate and systolic blood pressure, the surrogate determinants of external cardiac work (3) are more modest during dobutamine infusion compared with those observed during exercise (4). It has previously been shown that the frequency and extent of ischemia are more modest during dobutamine infusion compared with those observed during exercise (5,6). Many aspects of DSEchocardiographic protocols were developed from practices used in exercise treadmill protocols without clear consideration for dobutamine pharmacokinetics (7). The pharmacologie half life of dobutamine is 2 minutes, with steady state not obtained up to 10 minutes (8,9). In the United States, dobutamine protocols most commonly use 3 minute stages of increasing dobutamine doses. Thus, 3 minute dobutamine stage results in advancing the dose before achieving steady state. The limitation of 3 minute stages has been recognized clinically in the assessment of myocardial viability where low dose dobutamine is typically extended for at least 5 minutes (10,11,12).
KeywordsIschemia Dopamine Half Life Catecholamine Cardiol
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