Limitation of myocardial infarct size by a right ventricular assist device. To evaluate the effects of an RVAD on myocardial ischemic injury during right coronary artery (RCA) ligation, a pneumatically driven pusher plate pump was inserted between the right atrium and pulmonary artery, and the RCA was ligated at its origin for two hr. There were 18 sheep, of which nine each served as the control and RVAD groups. Hemodynamic parameters and blood samples were collected from the coronary sinus. Area at risk and area of infarct were detected by gentian violet injection and triphenyltetrazolium (TTC) staining. Hemodynamic parameters (left ventricular systolic pressure (LVSP), cardiac output (CO], and creatine kinase levels in coronary sinus blood tended to be beneficial, to some degree, in the RVAD group. Electron microscopic examination revealed chromatin clumping and mitochondrial destruction, however this ultrastructural damage was more severe in the control group. The ratio of area of infarct to area at risk in the RVAD group was significantly less than that in the control group, being 20.25 +/- 6.93% vs. 47.24 +/- 10.53% (p less than 0.05). The infarct size induced by RCA occlusion was significantly reduced by the RVAD, due to the right ventricular unloading via reduced myocardial oxygen demand. 