It is now clear dynamic cardiomyoplasty alone will not be able to support patients in severe cardiogenic shock. On the other hand, implantable univentricular electromechanically driven devices for permanent circulatory support are undergoing early clinical trials. Because of the potential for existing or subsequent biventricular failure and to avoid the need to implant two space-occupying mechanical devices, hybrid biomechanical assist devices could have certain advantages. To evaluate the feasibility of supporting profound biventricular failure, utilizing the combination of dynamic cardiomyoplasty and mechanical ventricular assistance, six dogs underwent simultaneous right latissimus dorsi cardiomyoplasty and left heart bypass. Microspheres were embolized into the pulmonary artery resulting in pulmonary hypertension and acutely impairing the right ventricle. The left ventricle was unloaded via a centrifugal Biomedicus pump. To create severe biventricular failure, the aorta was cross-clamped and potassium cardioplegia was infused into the aortic root to achieve a flaccid diastolic arrest of the heart. Infusion of microspheres into the pulmonary artery resulted in a dose-dependent increase in pulmonary artery pressure. Stimulation of the cardiomyoplasty under these conditions showed a 25.9 +/- 7.9% (S.E.M.) (p less than 0.05, paired t-test) increase in mean pulmonary artery flow. There was a corresponding increase of 6.75 +/- 10.6% in the centrifugal pump flow. Following diastolic arrest, the mean pulmonary artery and centrifugal pump flows increased 90.8 +/- 11.5% (p less than 0.001) and 16.4 +/- 12.1%, respectively. These preliminary results suggest this approach could be a useful alternative to patients who require long-term biventricular support.