An experimental contribution to the treatment of acute myocardial infarction.

1. Benzodiazepines and strong analgesics raise considerably the ventricular fibrillation threshold and thus electrically stabilize the heart in the early stage of myocardial ischaemia. 2. Benzodiazepines markedly potentiate the electrostabilizing effect of the beta-blocker metipranolol. 3. Trimecaine per se does not electrically stabilize the heart in the first hour of ischaemia. When combined with a benzodiazepine, trimecaine stabilizes the heart also in this early stage of myocardial ischaemia. 4. Infusion of a benzodiazepine (midazolam) combined with fractionated administration of a potent analgesic (fentanyl) does not produce pronounced changes in the haemodynamics and ventilation of healthy subjects. 5. Benzodiazepines and strong analgesics exert a favourable effect on the neurovegetative stress response in the early stage of acute myocardial ischaemia. They can be therefore recommended as a component in the treatment of patients with acute myocardial infarction.