RESUMO
OBJECTIVE: To observe the effects of local radiofrequency denervation on ventricular effective refractory periods, electrical alternans and ventricular arrhythmia susceptibility post myocardial infarction. MATERIALS AND METHODS: Thirty-four mongrel dogs were randomly divided into the normal heart group (n = 16, 8 in sham and 8 in local sympathetic denervation - LSD) and the acute myocardial ischemia (AMI) group (n = 18, 9 in control and 9 in LSD). The left cardiac sympathetic nerve was denervated with irrigated catheter radiofrequency ablation. Left ventricular effective refractory periods (ERP), monophasic action potential duration at 90% (APD90) and APD alternans were measured at baseline and 2 hours after LSD in the normal heart group. AMI was induced by ligating the left anterior descending coronary artery 2 hours after LSD was performed. Then APD90, the occurrence of ventricular arrhythmias (VAs) were measured. RESULTS: Compared with baseline, LSD significantly prolonged ventricular ERP and APD90 at all sites (p < 0.05 for all) in the LSD group, whereas no significant change was shown in the sham group. But their spatial dispersions did not change in both groups. APD alternans occurred at shorter pacing cycle length at each site after LADâLSD when compared to the sham group (p < 0.05 for all). After AMI, the occurrence of VAs was significantly lower in the LSD group than in the control group (p < 0.05). CONCLUSIONS: LSD may have a beneï¬cial impact on ventricular arrhythmias induced by AMI through modulation of autonomic tone.
