Radiofrequency catheter ablation and nerve growth factor concentration in humans.

BACKGROUND: In animal models, expression of nerve growth factor (NGF) is increased after necrotic myocardial injury. Whether radiofrequency (RF) catheter ablation increases NGF expression in humans is unclear. OBJECTIVES: The purpose of this study was to determine NGF concentrations in the aorta, coronary sinus, and peripheral veins before and after RF ablation in patients. METHODS: We sampled blood from aorta and either great cardiac vein (group 1, N = 18) or proximal (group 2, N = 20) coronary sinus before and after RF ablation. In group 3 (N = 21), peripheral venous blood was sampled before and after RF ablation and then up to postoperative day 7. In group 4 (N = 10), we sampled peripheral venous blood during diagnostic electrophysiologic study. The NGF concentration was determined by enzyme-linked immunosorbent assay. Transcardiac NGF concentration was the difference in NGF concentrations between coronary sinus and aorta. RESULTS: There was no change in transcardiac NGF concentrations in groups 1 and 2. In group 3, the NGF level did not change significantly from before the procedure (17.10 +/- 15.80 ng/mL) to immediately after the procedure (14.46 +/- 10.36 ng/mL). However, NGF levels increased significantly to 31.24 +/- 19.82 ng/mL (N = 21, P <.0001) on postoperative day 1, 26.23 +/- 16.89 ng/mL (N = 20, P <.001) on postoperative day 2, and 22.01 +/- 11.35 ng/mL (N = 16, P = .003) on postoperative day 3. NGF concentrations did not change significantly in group 4. CONCLUSION: RF ablation did not result in a detectable increase of transcardiac NGF concentration immediately after the procedure. However, the systemic NGF concentration increased significantly on postoperative days 1 to 3, suggesting that RF ablation resulted in increased NGF expression.

Hemodynamic and surface electrocardiographic effects of a new aqueous formulation of intravenous amiodarone.

Intravenous amiodarone is an effective antiarrhythmic agent. However, the standard formulation (Cordarone IV) frequently causes hypotension. Hemodynamic studies have attributed this adverse effect to the solvents employed. A newly developed aqueous formulation (Amio-Aqueous) lacks solvents and thus may not causes hypotension. This study evaluated the hemodynamic effects in a cardiac catheterization laboratory. Two boluses of 150-mg aqueous amiodarone were administered via a peripheral vein to 32 hemodynamically stable patients who underwent cardiac catheterization. Boluses were administered initially over 2 to 5 minutes and in the last 9 patients over 2 minutes. Hemodynamic evaluation was performed and 12-lead electrocardiograms were obtained at baseline, immediately after each bolus, and following 30 minutes of observation. No patient developed hypotension. There were no significant changes in systolic and diastolic blood pressure (BP) following the boluses. Compared with baseline, heart rate (HR) significantly decreased 5 minutes after the second bolus (73 +/- 12 vs 67 +/- 11 beats/min, p <0.05). Mean arterial BP increased (90 +/- 14 vs 100 +/- 16 mm Hg, p <0.05) and dp/dt decreased (1,599 +/- 645 vs 1,294 +/- 531 mm Hg/s p <0.05), whereas the PR, QT, and JT intervals increased (174 +/- 30 vs 182 +/- 33; 402 +/- 32 vs 424 +/- 35; 317 +/- 37 vs 336 +/- 32 ms, p <0.05, respectively) by the end of the 30-minute observation period. Amio-Aqueous possesses pharmacodynamic effects that have been attributed to amiodarone, whereas it lacks the hypotensive effect of the standard intravenous amiodarone formulation. Amio-Aqueous appears to be a safer alternative to Cordarone IV when rapid administration is indicated.

Biphasic versus monophasic shock waveform for conversion of atrial fibrillation: the results of an international randomized, double-blind multicenter trial.

OBJECTIVES: This study compared a biphasic waveform with a conventional monophasic waveform for cardioversion of atrial fibrillation (AF). BACKGROUND: Biphasic shock waveforms have been demonstrated to be superior to monophasic shocks for termination of ventricular fibrillation, but data regarding biphasic shocks for conversion of AF are still emerging. METHODS: In an international, multicenter, randomized, double-blind clinical trial, we compared the effectiveness of damped sine wave monophasic versus impedance-compensated truncated exponential biphasic shocks for the cardioversion of AF. Patients received up to five shocks, as necessary for conversion: 100 J, 150 J, 200 J, a fourth shock at maximum output for the initial waveform (200 J biphasic, 360 J monophasic) and a final cross-over shock at maximum output of the alternate waveform. RESULTS: Analysis included 107 monophasic and 96 biphasic patients. The success rate was higher for biphasic than for monophasic shocks at each of the three shared energy levels (100 J: 60% vs. 22%, p < 0.0001; 150 J: 77% vs. 44%, p < 0.0001; 200 J: 90% vs. 53%, p < 0.0001). Through four shocks, at a maximum of 200 J, biphasic performance was similar to monophasic performance at 360 J (91% vs. 85%, p = 0.29). Biphasic patients required fewer shocks (1.7 +/- 1.0 vs. 2.8 +/- 1.2, p < 0.0001) and lower total energy delivered (217 +/- 176 J vs. 548 +/- 331 J, p < 0.0001). The biphasic shock waveform was also associated with a lower frequency of dermal injury (17% vs. 41%, p < 0.0001). CONCLUSIONS: For the cardioversion of AF, a biphasic shock waveform has greater efficacy, requires fewer shocks and lower delivered energy, and results in less dermal injury than a monophasic shock waveform.