Converting enzyme inhibition by enalapril in experimental heart failure

We analyzed the effect of enalapril (0.1 mg/kg p.o. twice daily) on plasma electrolytes, urea, and creatinine in low cardiac output failure. In 14 male dogs implanted with chronic instrumentation, tachycardia was induced by ventricular pacing (265 impulses/min., 10-14 days). In 7 untreated dogs, pacing progressively lowered aortic flow by 44% and induced hyponatremia and elevations of plasma urea, creatinine, and potassium. Treatment with enalapril (n = 7) during pacing reduced the decrease in aortic flow by 33% and prevented changes in plasma urea, potassium, and sodium. We conclude that this is due to enalapril-induced retardation of heart failure progression.