Background-It is important to increase lesion size to improve the success rate for radiofrequency ablation of ischemic ventricular tachycardia. This study of radiofrequency ablation, with adjustment of power to approach a preset target temperature, ie, temperature-controlled ablation, explores the effect of catheter-tip length, ablation site, and convective cooling on lesion dimensions. Methods and Results-In vitro strips of porcine left ventricular myocardium during different levels of convective cooling and in vivo pig hearts at 2 or 3 left ventricular sites were ablated with 2-to 12-mm-tip catheters. We found increased lesion volume for increased catheter-tip length Յ8 mm in vitro (PϽ0.05) and 6 mm in vivo (PϽ0.0001), but no further increase was found for longer tips. For the 4-to 10-mm catheter tips, we found smaller lesion volume in low-flow areas (apex) than in high-flow areas (free wall and septum) (PϽ0.05). Increasing convective cooling of the catheter tip in vitro increased lesion volume (PϽ0.0005) for the 4-and 8-mm tips but not for the 12-mm tip as the generator reached maximum output. In contrast to power-controlled ablation, we found a negative correlation between tip temperature reached and lesion volume for applications in which maximum generator output was not achieved (PϽ0.0001), whereas delivered power and lesion volume correlated positively (PϽ0.0001). Conclusions-Lesion size differs in different left ventricular target sites, which is probably related to convective cooling, as illustrated in vitro. Longer electrode tips increase lesion size for tip lengths Յ6 to 8 mm. For temperature-controlled ablation, the tip temperature achieved is a poor predictor of lesion size. (Circulation. 1999;99:319-325.)

GLP-1 and PYY are both potent inhibitors of the cephalic phase of acid secretion, indicating that at least part of the inhibitory effect of GLP-1 and PYY in man is mediated through neural pathways. Furthermore, the inhibitory effect seems to be independent of circulating concentrations of gastrin and somatostatin.

The limited success rate of radiofrequency catheter ablation in patients with ventricular tachycardias related to structural heart disease may be increased by enlarging the lesion size. Irrigated tip catheter ablation is a new method for enlarging the size of the lesion. It was introduced in the power-controlled mode with high power and high infusion rate, and is associated with an increased risk of crater formation, which is related to high tissue temperatures. The present study explored the tissue temperatures during temperature-controlled irrigated tip ablation, comparing it with standard temperature-controlled ablation and power-controlled irrigated tip ablation. In vitro strips of porcine left ventricular myocardium were ablated. Temperature-controlled irrigated tip ablation at target temperatures 60 degrees C, 70 degrees C, and 80 degrees C with infusion of 1 mL saline/min were compared with standard temperature-controlled ablation at 70 degrees C and power-controlled irrigated tip ablation at 40 W, and infusion of 20 mL/min. Lesion size and tissue temperatures were significantly higher during all modes of irrigated tip ablation compared with standard temperature-controlled ablation (P < 0.05). Lesion volume correlated positively with tissue temperature (r = 0.87). The maximum recorded tissue temperature was always 1 mm from the ablation electrode and was 67 +/- 4 degrees C for standard ablation and 93 +/- 6 degrees C, 99 +/- 6 degrees C, and 115 +/- 13 degrees C for temperature-controlled irrigated tip ablation at 60 degrees C, 70 degrees C, and 80 degrees C, respectively, and 112 +/- 12 degrees C for power-controlled irrigated tip ablation, which for irrigated tip ablation was significantly higher than tip temperature (P < 0.0001). Crater formation only occurred at tissue temperatures > 100 degrees C. We conclude that irrigated tip catheter ablation increases lesion size and tissue temperatures compared with standard ablation in the temperature-controlled mode at the same or higher target temperatures and in the power-controlled mode. Furthermore, tissue temperature and delivered power are the best indicators of lesion volume during temperature-controlled ablation.

Ninety-five percent of the patients were content with the remote FU. Only 25% had unscheduled transmissions and most unscheduled transmissions were for appropriate reasons. Eighty-four percent of the patients wished for a more detailed response and 21% wished for a faster reply after routine transmissions.

Increasing co-morbidity burden was not associated with increased risk of appropriate ICD therapy. With increasing co-morbidity burden, mortality increased, and a higher proportion of patients died, without ever having utilized their device.