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Right ventricular (RV) failure has been reported to be a problem in 49 of 213 patients who received left ventricular assist devices (LVAD) at 12 different centers. Although the pathology of the problem is not understood, it is clear that the effect of an LVAD on hemodynamic ventricular interactions due to the right and left hearts being in series, and on mechanical ventricular interactions due to the anatomic coupling between the ventricles, could play a role in determining the ultimate fate of the right ventricle. Six hypotheses were generated concerning beneficial and detrimental effects of an LVAD on the determinants of right ventricular function (preload, afterload, contractility). The major potential effect on RV preload is increased venous return produced by the LVAD which can overload a marginal RV; but beneficial effects on RV preload and filling also can be produced by the LVAD unloading a dilated LV, thereby shifting the interventricular septum, which had encroached into the RV, back to the left. A significant beneficial effect on RV afterload can be produced with an LVAD by passive reductions in pulmonary artery (PA) pressure secondary to reductions in left atrial pressure; with pulmonary obstructive disease, however, PA pressures can increase due to the greater blood flow through the fixed pulmonary vascular resistance. The major effects on RV contractility produced by an LVAD are significantly beneficial since aortic and, therefore, coronary perfusion pressure is maintained. There also is a potential detrimental effect on RV contractility produced by decreased septal contribution to RV contraction during complete LV unloading with an LVAD. The initial therapy for the failing right ventricle in patients with an LVAD is volume loading. Isoproterenol, dobutamine, and dopamine can be used for inotropic support, and atrial pacing can improve the atrial contribution to filling. If these modalities fail, surgical techniques including pulmonary artery balloon pump or extracorporeal membrane oxygenation can be tried, but the recommended mechanical support is a right ventricular assist device.

Approximately 20% of patients who receive left ventricular assist devices (LVADs) for refractory cardiac failure after open heart surgery have had complications of right ventricular failure. To evaluate this problem in the diseased heart we simulated an LVAD in the operating room by bypassing and unloading the left ventricle with the heart-lung machine before routine open heart surgery. Right

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