Right heart interaction with the mechanically assisted left heart

Abstract

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.

Clinical management of continuous-flow left ventricular assist devices in advanced heart failure

“…LV unloading with a LVAD should decrease RV after-load by reducing pulmonary artery pressures (PAPs). 31 However, mechanical support may increase systemic venous return to a myopathic right heart that is unable to accommodate the additional volume. Furthermore, reduction in LV pressure can cause the interventricular septum to shift leftward, potentially causing disadvantageous geometric changes in the RV that reduce septal contribution to RV stroke volume and exacerbate tricuspid regurgitation.…”

Tod eines 79 Jahre alten Mannes mit einem linksventrikulären Herzunterstützungssystem

“…Als typische LVAD-Komplikationen gelten Blutungen, Infektionen, thrombembolische Ereignisse und Herzrhythmusstörungen sowie ein Rechtsherzversagen, insbesondere im Frühstadium nach dessen Implantation [3,5,11,15]. Durch maligne Herzrhythmusstörungen kann sich jedoch auch schnell ein akutes Rechtsherzversagen entwickeln [11].…”

Ventricular Assist Device – How to Obtain Optimal Benefits?

“…• Lowering pulmonary vascular resistance to optimize right-heart function and to reduce right atrial pressure and secondary hepatic congestion Left ventricular unloading with a LVAD should decrease right ventricular after-load by reducing pulmonary artery pressures (PAPs) (Farrar et al 1985). However, mechanical support may increase systemic venous return to a myopathic right heart that is unable to accommodate the additional volume.…”

“…However, mechanical support may increase systemic venous return to a myopathic right heart that is unable to accommodate the additional volume. Furthermore, reduction in left ventricle pressure can cause the interventricular septum to shift leftward, potentially causing disadvantageous geometric changes in the right ventricle that reduce the septal contribution to right ventricle stroke volume and exacerbate tricuspid regurgitation (Farrar et al 1985). Importantly, right ventricle failure after implantation can be anticipated preoperatively and improved with various therapies that optimize its function.…”