EFFECT OF LIGNOCAINE IN MYOCARDIAL CONTUSION - AN EXPERIMENT ON RABBIT ISOLATED HEART

1 The reported incidence of myocardial contusion after blunt chest tra uma varies from 16 to 76%. Of these patients, about 6% present a sever e, life threatening contusion. We used an isolated heart preparation t o examine the effect of lignocaine on myocardial performance after con tusion. 2 Thirty hearts obtained from male New Zealand rabbits were pe rfused at constant flow according to the Langendorff technique and wer e divided into four groups. The following parameters were measured at frequent intervals for 60 min: mean coronary perfusion pressure (CPP), left ventricular diastolic pressure (LVDP), developed pressure (DP), dP/dt(max), dP/dt(min). 3 Group 1 (n = 6) served as control, group 2 ( n = 7) received lignocaine for 20 min (15 mu M for the first 10 min an d 30 mu M for the following 10 min), group 3 (n=9) had a contusion lea ding to a 30-50% decrease in dP/dt(max) and group 4 (n=8) had the cont usion and the lignocaine infusion was started 10 min after the contusi on and stopped after 30 min. Lignocaine concentration was measured in the effluent. 4 Lignocaine alone moderately decreased contractility in group 2. In group 3, after contusion, DP, dP/dt(max), and dP/dt(min) were markedly decreased during the 60 min recording period. In group 4 , lignocaine infusion rapidly restored contractility. DP, dP/dt(max) a nd dP/dt(min) returned towards their basal values. This improvement of contractility remained stable, even after lignocaine infusion was dis continued. 5 In our rabbit isolated heart preparation, lignocaine at a low therapeutic concentration was able to restore contractility after contusion. These results need to be confirmed by other studies but th is may lead to promising therapeutic intervention.