Comparison of the effects of phentolamine and trinitrine in the treatment of left ventricular failure during the acute phase of myocardial infarct

: Two groups of 10 patients with left ventricular failure during the acute phase of myocardial infarction were studied. One group were given phentolamine, the other trinitrin. The infusion rate was regulated so that the heart rate was not increased by more than 10 beats per minute, and to obtain a pulmonary arterial diastolic pressure less than 18 mmHg with a mean systemic arterial pressure remaining greater than or equal to 80 mmHg. The dose of phentolamine was 5 +/- 3 mcg/kg/mn, but using trinitrin the initial optimal dose of 0.39 +/- 0.22 mcg/kg/mn had to be progressively increased during the first 24 hours. The haemodynamic study done before treatment and after an hour at the optimal infusion rate showed that, for a similar reduction in the pulmonary arterial diastolic pressure, the mean systemic arterial pressure was reduced less by trinitrin than by phentolamine, while the stroke work index was not appreciably altered by either drug. In patients with low systemic arterial pressure, trinitrin appears to be preferable and warrants use after the possible setting up of circulatory assistance by aortic counter-pulsation.