[The adverse effect of catheter ablation on the AV junction in experimental dogs]

The purpose of this study was to assess the adverse effects of catheter electrical ablation. Eighteen anesthetized mongrel dogs received 10-400 J of DC countershocks one to five times in each of them near the region of AVJ. Complete AV block was established, no pacemaker was implanted. Electrical unstability was seen nearly in all. Among the date of observation (1-547 days), 16 dogs died spontaneously and the other two were killed. Gross and microscopic examination revealed that cardiac damage produced by DC shock was diffusely spread over the endocardium/valve, myocardium and epicardial layers. The prominent lesions of the acute stage were myocytolysis and/or necrosis of myocardium/endocardium. In chronic stage, diffuse fibrosis and other types of tissue degeneration were revealed, some dogs had both acute and chronic lesions at the same time. Two dogs with perforated aortic valve revealed an elevation of PAEDP, one of them developed marked right heart failure and ascites. We proposed that the acute submicroscopic injury induced by DC shock may progress to a diffuse and irreversible pathologic changes. Therefore, the chronic adverse effects of catheter ablation should be evaluated carefully.