The Effect of Intracoronary Lidocaine on Ventricular Arrhythmia in the Infarcted Canine Heart

The efficacy of intracoronary administration of lidocaine was studied in three groups of dogs with experimental myocardial infarction induced by occlusion of the left anterior descending coronary artery (LAD). Group 1 included 14 anesthetized and group 2, 7 conscious animals to which lidocaine 1.4 micrograms/kg/minute was administered as an intracoronary infusion. Group 3 consisted of 17 anesthetized dogs that received an intracoronary bolus of lidocaine 40 micrograms/kg over 30 seconds. In group 1, lidocaine reduced ventricular arrhythmia by 59 +/- 30% (p less than 0.001), whereas systemic lidocaine achieved a reduction by 61 +/- 37% (p 0.06). In seven dogs, lidocaine blood levels were measured in the great cardiac and femoral veins. At the end of the infusion the drug concentration was 3.4 +/- 2.2 micrograms/ml in the great cardiac and 1.3 +/- 1.1 micrograms/ml in the femoral vein (p less than 0.05). The reduction in ventricular arrhythmia correlated with the great cardiac vein lidocaine concentration (r = 0.70; p less than 0.05), but not with the drug level in the femoral vein (r = 0.06; NS). In group 2, lidocaine was ineffective by both routes of administration. This may have been related to higher sympathetic activity, as suggested by an elevated heart rate in conscious compared to anesthetized animals (186 +/- 6 vs 164 +/- 21 bpm; p 0.0054). In group 3, bolus injections of lidocaine into the LAD reduced ventricular arrhythmia by 66% (p 0.001). We conclude that by perfusing the infarcted zone with lidocaine, a significant antiarrhythmic effect can be achieved with 2% of the systemic dose.(ABSTRACT TRUNCATED AT 250 WORDS)