Untitled

Abstract

The aim of this study was to determine the relationship between the size of discontinuities in lines of ablation and wavefront propagation. Discontinuities in linear radiofrequency lesions used for the treatment of atrial fibrillation may be proarrhythmic and a major clinical problem. A better understanding of the electrophysiological properties of these discontinuities (isthmuses) may assist in their detection and treatment. Linear lesions were made in the right atrial free wall using a Nd:YAG laser in 12 dogs. Conduction properties across the discontinuities were studied by pacing from either side of the lesion. Two of the three isthmuses less than 0.8 mm(2) in cross section (smallest 0.2 mm(2)) conducted at extrastimulus intervals of 300 ms. All three failed to conduct at cycle lengths close to the atrial effective refractory period. Isthmuses above 0.8 mm(2) (n¿=8) conducted at all cycle lengths. Conduction slowing (mean slowest conduction 0.5 +/- 0.3 m/s) occurred in the region of the isthmus but the overall delay was only 6 +/- 6 ms where propagation through the isthmus occurred. The effect on conduction of small discontinuities in linear lesions is dependent on the size of the residual isthmus. All but the very smallest of discontinuities in linear lesions conduct and therefore have the potential to participate in reentrant arrhythmias. Efforts should be directed toward the development of ablation techniques that reliably produce continuous transmural linear lesions for cure of atrial fibrillation and flutter.

2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation: Recommendations for Patient Selection, Procedural Techniques, Patient Management and Follow-up, Definitions, Endpoints, and Research Trial Design

“…253,436,507,508,622,623, 624,625,630,870,871,995,996,997,998,999,1000,1001,1002 Most of these tachycardias originate in the LA, although RA cavotricuspid isthmus (CTI)-dependent flutters might also occur. Patients with a regular AT of new onset might complain of worsening symptoms due to a faster mean ventricular rate (frequently 2:1 ventricular response) than that during AF preablation.…”

2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation

“…ATs of new onset make up to 50% of all arrhythmias observed following catheter-based ablation of AF. 253 , 436 , 507 , 508 , 622 , 623 , 624 , 625 , 630 , 870 , 871 , 995 , 996 , 997 , 998 , 999 , 1000 , 1001 , 1002 Most of these tachycardias originate in the LA, although RA cavotricuspid isthmus (CTI)-dependent flutters might also occur. Patients with a regular AT of new onset might complain of worsening symptoms due to a faster mean ventricular rate (frequently 2:1 ventricular response) than that during AF preablation.…”

Organized Atrial Tachycardias after Atrial Fibrillation Ablation

“…As a result, small gaps are usually characterized by long-duration and very fractionated potentials small gaps usually showing [93–95]. The overall delay is not exceedingly great in comparison to normal tissue [94] and has been deemed to lack clinical relevance, insofar as small gaps are still capable of relatively fast conduction [38]. The solid results of Melby et al [95] reaffirm both ideas: only very small gaps tend to manifest features of slow conduction (as a matter of fact, fragmented electrograms are a prominent distinctive mark of conduction gaps in the clinical setting [16, 38, 58]), and the overall conduction velocity impairment is small, allowing for effective conduction of very rapid paced rhythms and even AF.…”