In vivo effect of bradykinin during ischemia and reperfusion: improved electrical stability two weeks after myocardial infarction in the pig.

In this study, the effect of bradykinin or saline infusion during ischemia and reperfusion on electrical stability, 2 weeks after myocardial infarction, was assessed. Acute myocardial infarction was induced in 21 pigs by a transluminal occlusion of the left coronary artery with a catheter balloon, inflated for 45 min. Bradykinin was administered by a 30-min infusion that started after 30 min of coronary occlusion and was continued until 15 min after reperfusion. Although creatine kinase levels in bradykinin-treated animals were significantly lower (p less than 0.001), 2 week survival was not different between groups. In survivors, the filtered QRS (ventricular deflection) duration (detected using signal-averaged electrocardiography) was significantly prolonged in saline-treated pigs, whereas in bradykinin-treated pigs this prolongation was prevented. The terminal voltage of the QRS complex was significantly lower in saline-treated pigs than in bradykinin-treated pigs. These two parameters signify an improved electrical stability after bradykinin treatment. Refractory periods in saline-treated hearts were longer than in bradykinin-treated hearts (106 +/- 10% vs. 95 +/- 13%, p less than 0.05). Also, current thresholds in the infarct border zones showed a greater variance in saline-treated hearts (p less than 0.001), pointing toward more tissue heterogeneity of the infarct border zone. Programmed electrical stimulation showed a trend toward reduced inducibility of sustained ventricular tachycardia in bradykinin-treated hearts. Therefore, bradykinin improves electrical stability weeks after experimental myocardial infarction.