Ablation of ganglionated plexi
OKLAHOMA CITY, OK. Dr. Warren Jackman and his group at the University of Oklahoma Health Sciences Center present an excellent overview of the history of catheter ablation for atrial fibrillation (available at www.jafib.com). Dr. Jackman and colleagues cover developments from the first use of catheter ablation in 1994 to cure relatively simple arrhythmias, through Prof. Haissaguerre's 1998 discovery of the crucial role of pulmonary vein triggers in AF initiation, to the latest developments involving the ablation of areas exhibiting low-level complex fractionated atrial electrograms (CFAE) during AF episodes (Nademanee protocol).

Although standard pulmonary vein isolation (PVI) procedures carried out by highly skilled EPs are successful in about 90% of cases among paroxysmal afibbers, there is still considerable room for improvement when it comes to persistent and permanent afib. Dr. Jackman and his group now proposes that ablation of ganglionated plexi in the left atrium either by itself or in combination with a PVI procedure, a maze procedure or a mini-maze procedure may further improve success rates.

Ganglionated plexi (GPs) are the hubs or "command modules" of the intrinsic cardiac autonomic nervous system (ICANS). They are particularly well enervated with both adrenergic and vagal nerve endings and are housed in so-called "fat pads" which are mainly located in the area where the pulmonary veins enter the left atrium. Dr. Jackman and colleagues believe that afib episodes can be initiated by excessive vagal or adrenergic stimulation of the GPs and that ablation of the fat pads can substantially increase the chance of a successful ablation. The GPs can be located either on the inside (endocardial) or outside (epicardial) of the heart wall by high-frequency electrical activation.

A recent trial by Dr. Carlo Pappone's group in Milan found that a combination of a circumferential PVI and GP ablation resulted in 99% of 102 patients being free from afib after one year. A very small trial involving 18 patients claims a 94% success rate after one year with GP ablation alone. Similar promising results of GP ablation have been reported from cardiothoracic surgeons performing mini-maze procedures. Dr. Onorati and colleagues at the University of Catanzaro in Italy found that ablating GPs during mitral valve surgery resulted in 93% success as compared to 73% success in the group not undergoing GP ablation.

The Oklahoma researchers conclude that concomitant GP ablation may increase the success rate of catheter ablation and surgical procedures aimed at curing AF.

Scherlag, BJ, et al. The autonomic nervous system and atrial fibrillation: the roles of pulmonary vein isolation and ganglionated plexi ablation. Journal of Atrial Fibrillation, Vol. 1, August 2009, pp. 471-86

Editor's comment: The addition of GP ablation to the standard PVI procedure certainly looks promising. My only concern would be if this additional ablation, which obviously destroys parts of the heart's intrinsic regulatory mechanism, would result in the emergence of tachycardia or – not supported by any evidence I know of – increase the risk of sudden cardiac death.