Do overlapping vessels protect against canine right ventricular infarction after right coronary artery occlusion?

The severity of ischaemia in the left ventricle from total coronary occlusion is modified by retrograde blood flow through collateral or overlapping vessels, but whether that is true for the right ventricle is not known. The consequences and extent of ischaemic damage from occlusion of the right coronary artery were studied in anaesthetised dogs. In group 1 (n = 9), the right coronary artery alone was occluded; in group 2 (n = 8), the right coronary artery and overlapping vessels from the left anterior descending and circumflex coronary arteries were occluded. Occlusion for 2 h caused right ventricular end diastolic pressure to increase by 2.8(SEM 0.4) mm Hg in group 1 (p less than 0.05) and by 1.9(0.5) mm Hg in group 2 (p less than 0.05). Fractional shortening in the ischaemic zone became akinetic in group 1: 12.0(1.4)% v 0.1(1.6)%; p less than 0.05; and dyskinetic in group 2: 12.1(2.1)% v -1.2(0.9)%; p less than 0.05. In both groups, fractional shortening remained depressed during the ensuing 2 h of reperfusion. The incidence of right ventricular free wall necrosis was 56% in group 1 but 100% in group 2 (p = 0.082). The area of necrosis, expressed as a percentage of the area at risk, was 13.9(6.6)% in group 1 in contrast to 66.9(4.5)% in group 2 (p less than 0.05). Both groups had equal involvement of the subendocardial and subepicardial layers. We conclude that ligating epicardial overlapping vessels in addition to the right coronary artery produces a larger area of right ventricular free wall necrosis.