Serial assessment of circumferential regional left ventricular function following complete coronary occlusion.

The effect of abrupt coronary artery occlusion on regional left ventricular (LV) function is well known, but serial changes in circumferential regional function over the first few hours have not been extensively investigated. Circumflex coronary artery occlusion was produced in nine closed-chest, conscious dogs and changes in LV circumferential function were assessed using two-dimensional echocardiography (2DE) performed in the short-axis projection at the mid-papillary muscle level. End-diastolic and end-systolic frames were manually digitized and regional area ejection fractions at 22.5-degree intervals were calculated using a fixed diastolic center of mass. Endocardial motion abnormality was measured from a circumferential regional ejection fraction map. The extent of wall motion abnormality was measured as that exceeding 95% confidence limits of normal controls; the degree of dyssynergy was measured as the planimetered area of the extent of wall motion abnormality. Following circumflex coronary artery occlusion, a wall motion abnormality was well defined with a minute of occlusion and its circumferential extent measured 146 +/- 16 degrees with 11 +/- 2 cm2 absolute degree of dyssynergy. These parameters did not change over the course of the coronary artery occlusion. We conclude that circumferential regional abnormalities produced by coronary occlusions are well defined early and do not change over the first 3 hours of acute ischemia and infarction.