Effect of lignocaine in myocardial contusion: an experiment on rabbit isolated heart.

1. The reported incidence of myocardial contusion after blunt chest trauma varies from 16 to 76%. Of these patients, about 6% present a severe, life threatening contusion. We used an isolated heart preparation to examine the effect of lignocaine on myocardial performance after contusion. 2. Thirty hearts obtained from male New Zealand rabbits were perfused at constant flow according to the Langendorff technique and were 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/dtmax, dP/dtmin. 3. Group 1 (n = 6) served as control, group 2 (n = 7) received lignocaine for 20 min (15 microM for the first 10 min and 30 microM for the following 10 min), group 3 (n = 9) had a contusion leading to a 30-50% decrease in dP/dtmax and group 4 (n = 8) had the contusion and the lignocaine infusion was started 10 min after the contusion 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/ dtmax, and dP/dtmin were markedly decreased during the 60 min recording period. In group 4, lignocaine infusion rapidly restored contractility. DP, dP/dtmax and dP/dtmin returned towards their basal values. This improvement of contractility remained stable, even after lignocaine infusion was discontinued. 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 this may lead to promising therapeutic intervention.