Acute electrical isolation is a necessary but insufficient endpoint for achieving durable PV isolation: the importance of closing the visual gap.

AIMS: Temporary, ablation-mediated effects such as oedema may cause reversible pulmonary vein (PV) isolation. To investigate this, point-by-point circumferential ablation was performed to achieve acute electrical PV isolation with an incomplete circumferential ablation line. Then, the impact of this intentional 'visual gap' (ViG) on the conduction properties of the ablation lesion set was assessed with adenosine and pacing manoeuvres. METHODS AND RESULTS: Twenty-eight patients undergoing ablation for paroxysmal (n= 20) or persistent atrial fibrillation (n= 8) were included. Pulmonary vein (PV) ablation was performed around ipsilateral vein pairs. Once acute isolation was achieved, ablation was halted and the presence and size of the ViG were calculated. The ViG electrophysiological properties were tested with pace capture along the ViG at 10 mA/2 ms, and assessment for dormant PV conduction with adenosine. Despite electrical isolation, a ViG was present in 75% (n= 42/56) of vein pairs (21 of 28 left PVs and 21 of 28 right PVs). There was no difference in the ViG size between the left and right PVs (22.1 ± 14.2 and 17.3 ± 11.3 mm, P > 0.05). Dormant PV connections were revealed by adenosine in more than a quarter (n= 12/42) of acutely isolated PV pairs, of which the majority were dependent on conduction through the ViG. CONCLUSIONS: Electrical PV isolation can usually be achieved without complete circumferential ablation. However, more than a quarter of these 'isolated' PVs exhibit dormant conduction-predominantly via the un-ablated 'ViGs' in the ablation lesion set. These findings support the hypothesis that reversible tissue injury contributes to PV isolation that may be acute but not necessarily durable.

Ventricular arrhythmia: role of the implantable cardioverter defibrillator and radiofrequency ablation in addition to drugs.

The control of life-threatening arrhythmias in the prevention of sudden cardiac death has been a long-standing challenge to clinicians. Large-scale, randomized, controlled trials have contributed immensely to our understanding of the management of life-threatening arrhythmias. There are many causes of life-threatening ventricular arrhythmias, which they occur mostly in the setting of healed myocardial infarction. Available treatments for the management of ventricular arrhythmias include antiarrhythmic drugs, implantable cardioverter defibrillators and catheter ablation. Each therapy provides unique advantages for selected patients with life-threatening arrhythmias. Because the goal of arrhythmia management is not only to provide the single best therapy but to provide the greatest assurance of symptomatic arrhythmia control, the use of combined therapy has become a standard treatment strategy for patients with sustained ventricular arrhythmias. This review will discuss the different modes of treatment available for the treatment of life-threatening ventricular arrhythmias, and their potential risks and benefits. The rationale for using hybrid or combination therapy will be presented. Finally, some of the better-known primary and secondary prevention trials for treatment of ventricular tachycardias will be reviewed.