Effect of lignocaine on heart rate in patients with sinus bradycardia associated with proven or suspected acute myocardial infarction

Lignocaine was given as an intravenous (1 mg/kg body weight) or intramuscular (300 mg) injection to 26 patients with proven or suspected myocardial infarction, heart rate less than 60/min. A slight but significant increase in heart rate occurred and this response might be due to a vagolytic action of lignocaine. Two patients developed AV-junctional or idioventricular dysrhythmia after intravenous lignocaine. These patients did not show signs of clinical deterioration and the dysrhythmia reverted spontaneously. It can, however, not be denied that the drug was in some way responsible.