Comparison Of Left Ventricular Volume And Wall Stress With Dobutamine And Exercise Echocardiography

This prospective observational study will compare the physiologic responses between exercise stress echocardiography and dobutamine stress echocardiography on left ventricular volume and wall stress. Exercise and dobutamine stress testing are two widely employed diagnostic modalities that are often used, interchangeably, to detect inducible ischemia. We hypothesize that dobutamine leads to significantly lower ventricular volumes and wall stress than exercise. Some previous studies have shown that dobutamine and exercise echocardiography have comparable sensitivities and specificities, differences exist between the hemodynamic effects produced by each modality on the cardiovascular system. These variable effects may lead to differences in left ventricular size, volume and wall stress. If divergent left ventricular effects exist(between exercise and dobutamine induced stress), then the degree of myocardial oxygen consumption, ischemic burden, and ischemic threshold observed during exercise and dobutamine stress testing may be different between these commonly used modalities of stress testing. The potentially variable effects on the left ventricle in response to the modality used to induce stress would highlight a physiological difference between exercise and dobutamine stress testing. Differences in volumes and stress could also help explain the greater of ischemia and higher frequency of angina and ST-segment deviation which has been previously observed in some studies during exercise as compared to dobutamine echocardiography. The presence or lack of these expected hemodynamic responses may also have additional diagnostic and prognostic implications. The study involves the collection of data among patients undergoing stress echocardiograms that are clinically indicated. This data will be retrieved from the echocardiogram and report and medical chart, including baseline clinical characteristics, exercise parameters achieved during the test.