[Atrioventricular block induced by radiofrequency: electrophysiological criteria of success]

In a retrospective series of 18 consecutive patients (10 men, average age: 61.6 +/- 9.2 years) who underwent His bundle ablation by radiofrequency current, the authors analyzed the electrophysiological criteria predictive of complete atrioventricular block. A total of 82 radiofrequency bursts were analyzed (average: 4.5 +/- 3.1 bursts/patient) and classified as effective (N = 14, definitive atrioventricular block), ineffective (N = 55, no effect on atrioventricular conduction) or transiently effective procedures (N = 13, reversible Mobitz II atrio-ventricular block). Seven electrophysiological parameters were measured: HV interval, amplitude of atrial (A), Hisian (H) and ventricular (V) potentials, and the A/H, A/V, and V/H ratios before each radiofrequency burst. At the end of the ablation, 14 patients were in complete atrioventricular block and during the following 24 hours, a complete atrioventricular block developed in 3 other patients. The average value of the H potential was comparable in the effective and transiently effective procedures (0.28 +/- 0.20 mV and 0.27 +/- 0.19 mV respectively) and significantly higher than the same parameters in the ineffective group of procedures (0.65 +/- 0.14 mV, p = 0.008). The V/H ratio was progressively greater in effective (5.43 +/- 2.51), transiently effective (8.07 +/- 6.90) and ineffective procedure (14.32 +/- 13.35), p = 0.02; the average value of the A amplitude tended to be higher in the effective procedures (1.03 +/- 0.75 mV) and the transiently effective procedures (0.98 +/- 0.72 mV) than in the ineffective procedures (0.58 +/- 0.79 mV), p = 0.06. On the other hand, the other parameters were comparable in the three groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)