The efficacy of right atrial-pulmonary artery （RA-PA） bypass during acute right ventricular failure （RVF） produced by pulmonary artery constriction in dogs was examined in this study Control group （n=7） was supported with conventional volume loading and inotropic therapy. In the experimental animals （n=8）

RA-PA bypass was initiated 5 min. after the onset of severe RVF. Three control animals died from refractory ventricular fibrillation within one hour of RVF. No animals in the experimental group died within two hours of RA-PA bypass

but the histological study of the lungs in these animals demonstrated peribronchial

perivascular and intraalveolar hemorrhage. Light microscopic and electron microscopic examination of the myocardial specimens of the right ventricular free wall displayed the myocardial structures and ultrastructures were maintained effectively with RA-PA bypass while irreversible myocardial injuries occurred in the control animals after two hours of RVF with conventional therapy. During the 2 hours of RA-PA bypass

the hemodynamic indices were also maintained better when compared to the control animals. It may be concluded

a roller pump right ventricular assist device effectively unloads the acute failing right ventricle

maintains systemic cardiac output

and significantly reverses the myocardial ischemia during right ventricular failure

but RA-PA bypass may induce pulmonary hypertension due to increased pulmonary vascular resistance secondary to pulmonary edema and interstitial hemorrhage.