ELECTROANATOMIC MAPPING UNMASKS DIFFERENT MECHANISMS IN PATIENTS WITH ATRIOTOMIES FOR CONGENITAL HEART DISEASE

Parvin C. Dorostkar, Priscilla Piros, Albert L. Waldo, Mark D. Carlson, Niraj Varma,
Judith A. Mackall, Bruce S. Stambler, Melvin M. Scheinman
Case Western Reserve University, Cleveland, OH and University of California San Francisco, San Francisco, CA, USA

Abstract:  Background:  Repeated and staged operations increase the number and complexity of surgical incisions to the atria.  Purpose:  We compared the types and mechanisms of atrial tachycardias (ATs) in post-operative patients with congenital heart disease.  Methods:  We defined a simple atriotomy as one contiguous incision to the right atrium and a complex atriotomy as multiple, and/or staged atriotomies.  There were 21 patients who underwent electrophysiologic study with mapping and ablation.  Results:  In 12 patients with a simple atriotomy, 16 ATs were mapped:  there were 14 single loop reentry (88%) and two “Figure-of-8” reentry (12%) ATs.  In contrast, in 9 patients with complex atriotomies, 17 ATs were mapped:  there were 12 single loop reentry (61%), 4 “Figure-of-8” reentry (28%), and one focal (11%) AT.  Successful radiofrequency ablation was achieved in 14/16 ATs (88%) in patients with a simple, and in 13/17 ATs (75%) in patients with complex atriotomies.  Conclusions:  ATs in patients with simple atriotomies are more likely to have a simpler mechanism and are more successfully ablated.  In contrast, patients with complex atriotomies are more likely to have complex and varied underlying mechanisms and are more difficult to ablate.  These findings have important implications for pre-procedure planning and patient education.

INTRODUCTION

The approach to an atrial tachycardia in the electrophysiologic laboratory is especially challenging in patients with post-operative congenital heart disease [1], because traditional mapping techniques are hampered by poor definition of the underlying anatomic defect(s) and associated post-operative distortions and limited ability to describe impulse propagation because of lack of enough, high-density, electrogram recordings from remote or unusual sites within the atrium [2].

The purpose of this study was to describe tachycardia mechanisms in patients with congenital heart disease and to summarize ablative therapy in these patients.

METHODS

Our study cohort consisted of 21 consecutive patients with congenital heart disease and post-operative atrial tachycardia.  In addition to the traditional electrophysiologic approach, patients underwent mapping of the clinical tachycardia using the nonfluoroscopic, electroanatomic mapping system (CARTO).  Entrainment techniques were used to document that the mechanism of the tachycardia was reentrant and to identify a critical tachycardia isthmus.

RESULTS

Atrial tachycardias after simple atriotomy

In these patients with a simple atriotomy, successful ablation sites included the subeustachian isthmus in 6 of 16 tachycardias (38%), the area between double potentials from the posterolateral right atrial free wall and the inferior vena cava in 4 of 16 tachycardias (25%), and in other areas in 4 of 16 ATs (25%); Two of 16 ATs were not successfully ablated (12%).

Atrial tachycardias after complex atriotomy

In patients with complex atriotomies, successful ablation sites included the subeustachian isthmus in only 3 of 17 tachycardias (18%). Four of 17 ATs were not successfully ablated (25%).

Multiple tachycardias were present in 5 of 9 patients in contrast to only 2 of 12 patients after simple atriotomy.  “Figure-of-8” tachycardia occurred in 4 of 17 tachycardias in patients after complex atriotomy, in contrast to only 2 of 16 tachycardias in patients after simple atriotomy.

DISCUSSION

We found that only 27% of tachycardias involved the subeustachian isthmus with another 18% involving posterolateral double potentials and the inferior vena cava.

The type of the reentry tachycardia varied with the type and complexity of the surgical repair.  In addition, “Figure-of-8” tachycardias were noted in only 2 of 16 tachycardias after simple atriotomy, but 4 of 17 tachycardias after complex atriotomies (as high as 25%).

Because patients with congenital heart disease encompass a heterogeneous population and because surgical techniques are variable we found the use of multiple complimentary approaches to be of great benefit to successful treatment of these, often quite complicated, post-operative tachycardias.

REFERENCES

[1] R.J. Kanter, A Garson.  “Atrial arrhythmias during chronic follow-up of surgery for complex congenital heart disease”.  Pacing Clin. Electrophysiol. 1997;20:502-511.

[2] KK Collins, BA Love, EP Walsh, et al. “Location of acutely successful radiofrequency catheter ablation of intraatrial reentrant tachycardia in patients with congenital heart disease”.  Am. J. Cardiol. 2000;86:969-74.