Effects of left ventricular assist for cardiogenic shock on cardiac function and organ blood flow distribution.

Organ blood flow distribution was studied in dogs subjected to a left ventricular assist device (LVAD). In normal hearts (group 1), left ventricular work was reduced by 25% when 35% of cardiac output was performed by the LVAD. Organ perfusion, measured with tracer microspheres, remained normal or slightly increased. After induction of cardiogenic shock (group 2), perfusion deteriorated in all organs, but first in the brain, kidney, and intestinum. All animals died within 1 hour. When maximal inotropic support was administered after shock (group 3), hemodynamics improved but perfusion to most organs decreased progressively and 83% of animals died within 2 hours. When the LVAD was inserted after shock but without inotropic support (group 4), perfusion of all organs became normal during LVAD except for kidney flow, which remained severely depressed (56% of preshock value). After LVAD insertion, hemodynamics did not recover completely, and 33% of the animals died within 3 hours. When use of the LVAD was combined with 5 micrograms.kg-1.min-1 of dopamine after shock (group 5), organ blood flow distribution became normal during and after LVAD use except for renal flow, which was significantly impaired (83% of preshock value). Hemodynamics recovered after LVAD use, and all animals survived in this group. We conclude that use of the LVAD combined with low-dose positive inotropic support can prevent deterioration of organ perfusion after cardiogenic shock except for kidney.