Myocardial function in general and regional left ventricular ischaemia in dogs at control and high aortic blood pressure.

End-diastolic dilation and reduced systolic shortening are the characteristic dimensional changes during myocardial ischaemia. Elevation of systolic aortic blood pressure by 5.3 kPa (40 mm Hg) normalized shortening and reduced myocardial dilatation when the tissue rendered ischaemic by coronary artery occlusion was less than 20% of the left ventricle. However, when the ischaemic lesion was more extensive, an adverse effect of raising aortic blood pressure was observed.