[Catheter ablation after the direct electrical recording of the bundle of Kent. Apropos of 3 cases].

The success rate of catheter ablation, the latest therapeutic method in the treatment of cardiac arrhythmias, varies according to the precise indication. The best and most logical guarantee of its efficacy is the application of the electrical energy at an anatomical site essential to the arrhythmia. In preexcitation syndromes this site is without doubt the accessory pathway itself rather than its insertions, but this implies the recording of its activation. We recorded the electrical activation of a right sided Kent bundle in three consecutive cases to guide the therapeutic procedure (comparable to the recording of the H potential for his bundle ablation). All patients had paroxysmal atrial fibrillation (minimal RR interval: 175, 150 and 200 ms) and orthodromic reciprocating tachycardia. Two patients had had attacks of ventricular fibrillation. The sites of the Kent bundles were posteroseptal in 2 cases and anterolateral in 1 case. The recording of the electrical activation of the Kent bundle was validated by: the passage (induced or spontaneous) of a preexcited to a normal QRS coincident with the disappearance of the K potential; the exclusion of an atrial or ventricular origin of the electrical activation supposed to be the activation of the Kent bundle; electrical stimulation at the site of the recording of the K potential leading to prolongation of the stimulus-delta wave interval from 10 to 35 ms, with QRS morphology identical to the spontaneous complexes. All 3 patients were clinically cured by catheter ablation at the site of recording of the Kent bundle activation with follow-up periods ranging from 10 to 16 months.(ABSTRACT TRUNCATED AT 250 WORDS)