Collateral vessel development after right ventricular infarction in the pig

Although the right coronary artery supplies both ventricles in the pig, a gradual proximal right coronary occlusion produces infarction in the left ventricle, whereas the right ventricle is usually spared. This study evaluates the influence of right ventricular hypertension and hypertrophy (RVHH) on the occurrence of right ventricular infarction and the difference in the rate and extent of collateral vessel development after gradual right coronary occlusion in pigs with (RVHH group) and without (control group) increased right ventricular pressure and mass. Right ventricular hypertension and hypertrophy were induced by pulmonary arterial banding which raised right ventricular systolic pressure from 24 to 74 mm Hg and doubled right ventricular mass in 4 weeks. Right coronary occlusion was produced with an ameroid constrictor in 24 control group pigs and 15 RVHH pigs. Serial selective coronary cineangiograms on days 4, 8, 14, 21 and 28 after ameroid constrictor placement showed no difference in first appearance of collateralization to the occluded right coronary artery. Total collateralization, which was present in all pigs studied in the control group by days 21 and 28, was present in only 57 percent of the RVHH group at the same time. Although left ventricular infarction occurred in all animals in both groups, right ventricular infarction was not found in the control group but was seen in 80 percent of the RVHH group. There was no correlation between the degree of collateralization seen and the size of the right ventricular infarction found. Experimentally induced right ventricular hypertrophy and hypertension make the right ventricle susceptible to infarction and impeded total collateral filling of the occluded right coronary artery in some of the animals studied.