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EXPERIMENTAL STUDY

Attenuation of interatrial conduction using right atrial septal catheter ablation

David Schwartzman, MD, FACC^*, Eduardo N. Warman, PhD, William A. Devine, BS and Rahul Mehra, PhD

^* Atrial Arrhythmia Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
Medtronic, Inc., Minneapolis, Minnesota, USA
Department of Pathology, Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA

Manuscript received July 6, 2000; revised manuscript received May 21, 2001, accepted June 4, 2001.

Reprint requests and correspondence: Dr. David Schwartzman, Cardiovascular Institute, Presbyterian University Hospital, B535, 200 Lothrop Street, Pittsburgh, Pennsylvania 15213-2582
schwartzmand{at}msx.upmc.edu

OBJECTIVES

We sought to characterize a method of attenuating interatrial conduction using radiofrequency ablated lesions applied to the right atrial septum.

BACKGROUND

Interatrial conduction occurs in specific zones. Recent data suggest that interatrial conduction can be important in triggering and sustaining atrial fibrillation. Therefore, a method for attenuating interatrial conduction may have therapeutic value.

METHODS

In 13 healthy pigs, interatrial conduction was evaluated before and after sequential ablation of the right atrial septum, targeting interatrial conduction zones. In six animals, zone 1 (crista terminalis and limbus) was ablated first, followed by ablation of zone 2 (fossa ovalis and coronary sinus ostium). In the other seven animals, the order of ablation was reversed. Electrophysiologic and pathologic findings were correlated.

RESULTS

After ablation of zone 1, interatrial conduction was slowed, but there was no block. After ablation of zone 2, conduction was unchanged. After ablation of both zones, complete block was observed in four animals, and there was left atrial quiescence. In the remaining nine animals, incomplete block was observed, with marked conduction slowing or block during sinus rhythm and pacing. Ablation did not adversely affect atrioventricular node conduction, nor did it facilitate sustenance of an atrial arrhythmia. Pathologic analysis revealed that complete interatrial conduction block was associated with confluent ablation of both targeted zones.

CONCLUSIONS

Catheter ablation of the right atrial septum attenuated interatrial conduction without disturbing atrioventricular conduction.

Abbreviations and Acronyms   AF = atrial fibrillation   AVN = atrioventricular node   max = maximal difference between interatrial conduction times during atrial extrastimulation   ERP = local atrial effective refractory period   ICE = intracardiac echocardiography   ICT = interatrial conduction time, measured by interval between RAA and LAA   LAA = left atrial appendage   PDur = maximal duration of surface P wave, derived from 12-lead electrocardiogram   RAA = right atrial appendage   SCL = sinus cycle length

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