Lignocaine: effects on coronary blood flow in patients with recent myocardial infarction.

The myocardial clearance of rubidium may be obtained by praecordial counting after a single intravenous injection of Rb86Cl.Eight patients with a recent myocardial infarction had this determination performed before and 5 minutes after the intravenous injection of Ioo mg lignocaine.The average myocardial clearance of Rb was 45+ 26 ml/mmn per IOO g myocardium before lignocaine.This compared to the normal value in our laboratory of 72±2I ml/min per IOOg.After lignocaine the average myocardial clearance rose to 76 ± 32 ml/min per IOO g myocardium.The explanation of thisfinding as well as possible clinical applications are presented.Lignocaine is an effective antiarrhythmic agent.It is the most widely used drug in the management of ventricular tachycardia and ventricular ectopic beats occurring as complications of acute myo- cardial infarction (Frieden, I965; Gianelly et al., I967).Many investigators have shown that in thera- peutic doses lignocaine does not cause significant alterations in cardiac output, stroke volume, or mean arterial pressure in patients with an acute myocardial infarction (Stannard, Sloman, and Sangster, I968; Rahimtoola et al., I97I).In spite of the apparent value of the drug, there is no in- formation on its effects on coronary blood flow in man.Recently, Donato, Bartolomei, and Giordani (I964) and Donato et al. (I966) have described a simple, relatively non-invasive technique for meas- uring coronary blood flow.This method uses radioactive rubidium and external counting.The major advantage of this technique is the avoidance of coronary sinus or coronary artery catheterization which enhances the practical value of this method.The procedure is, therefore, without hazard to the patient and the equipment required for the per- formance of the test is in most well-equipped radioisotope laboratories.Another advantage of this technique is that the entire measurement may be completed in go seconds as compared to the time-consuming N20 or 131I antipyrine method.