[Regional myocardial ischemia in the conscious dog under echocardiography control]

Regional myocardial dysfunction is a very sensitive and early parameter of myocardial ischemia. One minute occlusion of the left anterior descending (LAD (n = 8) and circumflex coronary artery (CCA) (n = 8) by means of hydraulic occluders was performed in 10 chronically instrumented conscious dogs. In a left ventricular cross-section diastolic and systolic area (DA, SA) and area shortening (AS) as well as regional function of 6 radial sectors were evaluated with 2D echocardiography. After occlusion of the LAD, SA increased by 33% (p less than 0.05), AS decreased by 22% (p less than 0.05) while the DA remained unchanged. In 2 of 6 radial sectors (anteroseptal) shortening decreased by 41% (p less than 0.01) and 54% (p less than 0.001) respectively. Occlusion of the circumflex coronary artery CCA caused an increase in DA (18%) and SA (33%) and a reduction of AS by 24% (p less than 0.01). Contraction of the anterior wall (sectors 2 and 3) was reduced by 61% and 57% (p less than 0.001). In the same animal 10 one minute occlusions of the LAD with 5 min intervals of reperfusion caused a reproducible depression of sector 6 (septal) from 63.2 +/- 5.4% to 16.3 +/- 3.4%. In another animal 11 one minute CCA occlusions with 5 min intervals of reperfusion reproducibly decreased the contraction of sector 3 (anterior) from 85.2 +/- 6.7% to 21.4 +/- 17.0%. 2D-E allows a reproducible estimation of regional left ventricular dysfunction during ischemia. Our model has the advantage that numerous studies can be performed in the same animal, so that the results can be compared intraindividually.