This study in the pig was designed to characterize right ventricular (RV) contractile responses during infarction involving three areas of the heart--anteroseptal, anterolateral, and inferoseptal. Porcine coronary architecture was studied from multicolor vinyl casts. Distribution of blood supply to ventricular myocardium and papillary muscles was defined by intra-arterial dye injection. High-fidelity pressure and flow data were measured simultaneously in both ventricles following ligation of approximately equal lengths of the anterior descending, left circumflex, or posterior descending arteries. In the three groups, weight of myocardium involved by the occluded artery was comparable and there was significant depression of left ventricular performance, more pronounced in the two anterior infarcts. However, in anterolateral infarction, despite the obligatory drop in RV flow, there was no significant alteration in RV end-diastolic pressure (EDP), peak rate of rise of RV pressure (dP/dt), or time-to-peak developed dP/dt. In contrast, with both anteroseptal and inferoseptal infarctions there were significant alterations in all RV contractile parameters, at increased levels of RVEDP, signifying a primary depression in RV contractile state. With inferoseptal infarction, further occlusion of the right coronary near its origin produced a more exaggerated and selective RV contractile abnormality and, in half of the animals, varying degrees of acute tricuspid insufficiency.