Left Atrial Circumferential Pulmonary Vein Ablation For Treatment Of Paroxysmal Atrial Fibrillation To Sinus Heart Rate Turbulence And Heart Rate Variability Study

Part one Alterations of Heart rate turbulence: immediate vagal reflex during left atrium circumferential pulmonary vein ablationPurpose To observe the alteration of Heart rate turbulence(HRT) before and after left atrium circumferential ablation surrounding pulmonary veins(LACA) in patients with paroxysmal atrial fibrillation(PAF) to indicate whether concealed vagal denervation happened during the procedure.Methods Forty four(26 male, aged 53±11 years) patients with paroxysmal atrial fibrillation were included in the study referred for catheter ablation treatment from Mar 2006 to Dec 2006. The left atrium circumferential ablation surrounding pulmonary veins were done in every patients to achieve complete electrical isolation of both ipsilateral pulmonary veins. RS2 extrastimulus were delivered from right ventricular apex to obtain heart rate turbulence with 60％of basic sinus cycle length and at twice diastolic threshold before and after the procedure. Turbulence onset[To(％)] and Turbulence slope[TS(msec/beat)] were obtained averagely from five respective ventricular premature beats.Results TO and TS significantly changed after LACA[-0.0216±0.0236 to 0.0009±0.0133(P＜0.001)]and [7.3318±6.9835VS2.0553±2.1724 respectively (P＜0.001)].Conclusion Though vagal reflex with significant bradycardia and hypotension might happen during LACA procedure, HRT alteration, which indicates the concealed vagal denervation, is more common. This might contribute to the long term success of LACA treatment of PAF to some extent. Alteration itself also illustrates that the ablation damages or stimulates not the efferent but the afferent limb of the vagal reflex. Part two The effect of left atrium linear lesion encircling Pulmonary veins on the heart rate variabilityPurpose To evaluate the effect of left atrium linear lesion encircling pulmonary veins on the autonomic nervous system via the alternations of the heart rate variability.Methods Twenty five patients with paroxysmal atrial fibrillation were referred for catheter ablation treatment from Jan 2006 to Jun 2006. The left atrium linear lesion encircling pulmonary veins were done in every patients to achieve the disappearance of the pulmonary vein potentials. The maximal heart rate, minimal heart rate, mean heart rate, time domain and frequency domain analyses of HRV were obtained by use of 24-hour ambulatory electrocardiogram before and 3 days after the procedure.Results The parameters of MaxHR, MinHR, MeanHR, SDNN, SDANN, RMSSD, PNNS0, LF, HF, LF/HF were151, 47, 70, 126, 111, 27, 6, 98, 86, 2.4 before theprocedure, and 136, 66, 84, 57, 53, 16, 2, 18, 16, 1.2 after the ablation(P＜0.05).Conclusion The left atrium linear lesion encircling pulmonary veins significantly altered the heart rate variability which demonstrated the damage to the cardiac nervous system and this "neurogenic substrate modification" might be one of the mechanism of catheter ablation of atrial fibrillation.