Electrocardiographic Comparison of Dobutamine and BRUCE Cardiac Stress Testing With High Resolution Mapping in Experimental Models.

Clinical tests to detect acute myocardial ischemia induce transient cardiac stress by means of exercise or pharmaceutical stimulation and measure electrical changes of the heart on the body surface via an electrocardiogram (ECG). Such tests assume that both stress mechanisms induce identical-or at least similar-forms of ischemia. To improve electrocardiographic detection of myocardial ischemia, we must study how varied stressing agents (pharmacological or paced stressors) change electrocardiographic signatures. We simultaneously measured electrical recordings within the myocardium, on the epicardial surface, and on the body surface. We then induced acute, controlled ischemia and monitored the electrical response. To create the hemodynamic substrate for ischemia, we applied a hydraulic occlusion to the left anterior descending coronary artery. We varied the ischemic stress with two clinical protocols, the BRUCE and dobutamine stress tests. Our results suggest significant differences in the recorded electrical signal between stress mechanisms. Differences include the location, volume, and temporal development of ischemia throughout a stress episode. These results, and the experimental means used to obtain them, are a significant breakthrough in the field with simultaneous, high density electrical recordings within the myocardium and on the heart and torso surfaces.