The role of the accessory pathway radiofrequency catheter ablation in the secondary prevention of the malignant tachyarrhythmias in patients with Wolff-Parkinson-White syndrome

Background/Aim. The occurrence of atrial fibrillation (AF) in the presence of an accessory pathway (AP) that conducts rapidly is potentially lethal because the rapid ventricular response may lead to ventricular fibrillation (VF). The aim of the study was to determine long-term efficacy of AP catheter-ablation using radiofrequency (RF) current in secondary prevention of VF in WPW patients. Methods. Study included a total of 192 symptomatic WPW patients who underwent RF catheter-ablation of AP in our institution from 1994 to 2007 and were available for clinical follow-up for more than 3 months after procedure. Results. Before ablation, VF was recorded in total of 27 patients (14.1%). In 14 of patients (51.9%) VF was the first clinical manifestation of WPW syndrome. A total of 35 VF episodes were identified in 27 patients. The occurrence of VF was preceded by physical activity or emotional stress in 17.1% of cases, by alcohol abuse in 2.9% and by inappropriate intravenous drug administration in 28.6%. In addition, no clear precipitating factor was identified in 40% of VF cases, while informations about activities preceding 11.4% of VF episodes were not available. The follow-up of 5.7 ? 3.3 years was obtained in all of 27 VF patients. Of the 20 patients who underwent successful AP ablation, all were alive, without syncope or ventricular tachyarrhythmias during long-term follow-up. In 4 of 7 unsuccessfully treated patients, recurrence of supraventricular tachycardia and/or preexcited atrial fibrillation were recorded; one of these patients suddenly died of VF, 6 years after procedure. Conclusion. In significant proportion of WPW patients, VF was the first clinical manifestation of WPW syndrome, often precipitated by physical activity, emotional stress or inappropriate drug administration. Successful elimination of AP by percutaneous RF catheter-ablation is highly effective in secondary prevention of life-threatening tachyarrhythmias in patients with ventricular preexcitation.

[Physical and biophysical aspects of high energy intracardiac electrical discharges. II. Correlations between the physical and electrical effects of liminal and infraliminal shocks]

The electrical phenomena produced during the fulguration impulses are analyzed using a digital oscilloscope which enables the calculation, with precision, of the energies consumed all along the curve or between chosen times. Moreover, it enables the calculation of the corresponding impedance values and shows that the latter varies during all the discharge. The explanation for these impedance variations is obtained thanks to rapid cinematography, showing the formation of the fulguration bubble. Hence, one can observe an impedance variation which is quite distinctive from the one which would correspond to the simple passage of an electrical current in saline solution. Particularly at the end of the impulse, an important increase in the impedance corresponds to the loss of ionization of the bubble. Therefore, by simply reading these electrical parameters, it is possible to know the main stages of the fulguration phenomenon for impulses situated around the deflagration threshold.

[Physical and biophysical aspects of high-energy intracardiac electric discharges. I. The discharge bubble]

Endocavitary discharge produces an electrical spark at the end of the probe. This in turn produces a plume of steam which lasts for about ten milliseconds and which subsequently acts like a cavitation bubble. This phenomenon is well known in the branch of physics dealing with dynamics and fluids, and should be subjected to rapid kinetic recording. It may make it possible to explain various barotraumas which are observed during the discharge. However, the plumes of steam produced by the discharge have some highly specific features which are due to the fact that the discharge is usually produced using a monopole in an electrolyte. In addition, the shape of the electrode also affects the formation of the bubble. This results in a description of the cavitation bubble produced by the discharge as the "discharge bubble".