Effects of verapamil on heart and circulation in hemorrhagic shock in dogs.

Myocardial blood flow and left ventricular oxygen utilization were studied in verapamil-treated and untreated pentobarbital-anesthetized dogs subjected to hemorrhagic shock. Blood loss was similar in both groups. The dogs treated with verapamil (n = 15) during shock had a slower heart rate and lower left ventricular oxygen utilization than the untreated dogs (n = 14). Nevertheless, the treated dogs had a significantly higher myocardial blood flow and were able to maintain a higher cardiac index. Thus, verapamil has beneficial hemodynamic and metabolic effects that preserve myocardial function. These effects may explain the improved survival and protection of the heart against anatomic lesions, which have been demonstrated previously in dogs treated with verapamil during hemorrhagic shock.