Catheter Ablation of Atrial Arrhythmias in the Setting of Congenital Heart Disease

In this article, the authors provide an overview on the major types of congenital heart disease surgery such as biventricular repair, the modified Fontan procedure, and atrial baffle procedures, and include details on catheter-based therapies.

Introduction

Surgery for the palliation and repair of congenital heart disease has progressed dramatically since it was first introduced over 60 years ago.¹ Children who would have once succumbed to an early demise in infancy are now able to survive into adulthood. Unfortunately, a large proportion of these patients will develop atrial arrhythmias over the ensuing years, resulting in significant morbidity and mortality in a population already compromised by residual hemodynamic disturbances.^2-4 As this population continues to age, the number of individuals with repaired congenital heart disease who will develop an atrial arrhythmia is expected to reach unparalleled proportions.⁵

Differences in arrhythmia burden vary most dramatically by the type of underlying congenital heart defect, the patient’s age at the time of corrective surgery, and the time elapsed since the surgery was performed.⁶

Variations in incidence of atrial arrhythmia are also closely linked to the number and extent of atrial suture lines as well as residual hemodynamic alterations after repair. For instance, the highest incidence of atrial arrhythmia is found in single ventricle patients after atriopulmonary Fontan surgery, which involves extensive suture lines and ongoing atrial dilation.

Catheter-based ablation has emerged as an effective treatment modality for this group of patients with improved success rates over the past decade.^7-8 This is owed, in large part, to the introduction of electroanatomical mapping techniques with the ability to accurately define the tachycardia circuit. Verification of the mechanism through conventional entrainment maneuvers is still considered vital to a complete understanding of the tachycardia substrate. The major classes of congenital heart disease surgery are reviewed in this article with an emphasis on the various tachycardia substrates and their catheter-based therapies.

Biventricular Repair of Congenital Heart Disease

Biventricular repair in the setting of congenital heart disease ranges from such diverse malformations as simple atrial septal defects (ASD) to more complex lesions such as tetralogy of Fallot and transposition of the great arteries. Long-term follow-up data with regard to arrhythmia burden in general varies by type of congenital malformation, with estimates of approximately 30% after 10 years for the most common cyanotic congenital heart lesion, tetralogy of Fallot.⁹

Mechanisms of atrial arrhythmia in this group of patients are frequently, but not invariably, related to a circuit involving the tricuspid valve annulus much like typical cavotricuspid isthmus-dependent atrial flutter (Figure 1). As opposed to typical flutter circuits encountered in structurally normal hearts, these patients may have simultaneous reentry around an atriotomy incision in addition to the tricuspid valve annulus, the co-occurrence of which is known as dual-loop reentry.^10-11 Ablation of only a single circuit in these cases will not eliminate the arrhythmia substrate, leaving the patient with inducible atrial tachycardia. Therefore, thorough mapping of the right atrial free wall with attention to atriotomy scar and areas of block in the crista terminalis is essential (Figure 2). In addition, regions of scar, prior suture lines, and surgical patch material may result in variations of the typical flutter circuit, such that even though the typical cavotricuspid isthmus may form part of the reentrant pathway, alternative ablation sites serve as more effective targets (Figure 3). Our approach, similar to that of Nakagawa and colleagues, is to perform careful electroanatomical mapping with targeting of sites that require the fewest number of lesions to interrupt the circuit.¹² This approach is expected to result in a decrease in arrhythmia recurrence, simply because residual conduction through the limited ablated areas is less likely than through more extensive and longer lines.

Modified Fontan Procedure

Shortly after the introduction of the Fontan procedure, the increased propensity of this population to develop atrial arrhythmia was realized. It is now known that the incidence of atrial arrhythmia increases linearly with time after Fontan surgery, with an incidence of greater than 50% at 20 years.¹³ Complicating matters, tachycardia circuits in this group are rarely those of typical cavotricuspid isthmus-dependent atrial flutter and are more often the result of intra-atrial reentrant tachycardia (IART), with special predilection for sites involving the right atrial free wall.¹⁴  Depending on the underlying congenital heart disease, the substrate for typical isthmus-dependent atrial flutter may not even exist in this group of patients, and unique circuits such as pericaval reentry have instead been implicated.¹⁵

The most recent modification of the Fontan operation, the extracardiac conduit, was designed to reduce arrhythmia burden in this population by improving flow dynamics through the systemic venous conduit. The notion was that the longstanding elevation of right atrial pressure and atrial dilatation as noted in previous iterations of the Fontan procedure would be avoided. Although this approach has indeed reduced the overall arrhythmia burden for this population, it has unfortunately introduced a new obstacle, namely that of hindering catheter access to the atrial substrate. Not only is the systemic venous circulation separated from the atrium after this surgery (which by itself poses an impediment to catheter access), but the intervening material is often composed of Dacron or GORE-TEX^®, which may or may not be directly adherent to the atrial wall. Despite these challenges, we have found that catheter ablation in this population is possible using a combination of the conventional transseptal puncture technique and radiofrequency energy to perforate the surgical material and enter the atrial chamber (see online figure).¹⁶ We have subsequently performed this procedure on other patients with good results (unpublished data).

Atrial Baffle Procedures

The Senning operation for transposition of the great arteries and later the Mustard procedure^17-18 were designed to redirect systemic and pulmonary venous flow to the appropriate arterial outlet, so that physiologic correction of the circulation could be achieved. Despite various modifications, these procedures inevitably result in multiple suture lines in the right atrium as well as frequent loss of sinus rhythm. These changes contribute to the development of sinus node dysfunction and atrial tachycardia in this patient population, with only approximately 50% of patients remaining in sinus rhythm 10 years after repair.¹⁹

Atrial tachyarrhythmias in this population most commonly are the result of cavotricuspid isthmus-dependent atrial flutter and less frequently, circuits involving the morphologic right atrial free wall. As opposed to the usual situation, the typical flutter isthmus is partitioned into both systemic venous and pulmonary venous portions by a surgically created baffle that transects this region.²⁰ Although the reentrant circuit can occasionally be interrupted exclusively from the systemic venous side, a complete line of block is usually only achieved by either the retrograde approach or by trans-baffle puncture to reach the tricuspid valve annulus.²¹ For tachycardia circuits involving the native right atrial free wall, the trans-baffle approach is ideal to ensure detailed mapping and better catheter stability. Moreover, the trans-baffle approach provides added benefit of reduction in trauma to the aortic and tricuspid valves, which are necessarily crossed during the retrograde approach, as well as a lower risk for AV block. 

Conclusions

With the advent of catheter ablation and newer electroanatomical mapping strategies, the treatment of atrial rhythm abnormalities in the congenital heart disease population has improved dramatically. Knowledge of the anatomy of the various congenital heart malformations and the details of surgical repair is vital to successful catheter ablation of these atrial arrhythmias. Although the mechanisms of tachycardia associated with certain malformations and their associated surgical repairs are well described, reentrant circuits are often patient-specific, requiring detailed electroanatomical mapping. A combination of conventional mapping techniques combined with newer catheter navigation technologies is currently the most effective approach to these challenging patients.

References

1. Blalock A, Taussig HB. The surgical treatment of malformations of the heart in which there is pulmonary stenosis or pulmonary atresia. JAMA. 1945;128:189-202.
2. Ghai A, Harris L, Harrison DA, et al. Outcomes of late atrial tachyarrhythmias in adults after the Fontan operation. J Am Coll Cardiol. 2001;37:585-592.
3. Gatzoulis MA, Walter J, McLaughlin PR, et al. Late arrhythmia in adults with the Mustard procedure for transposition of the great arteries: A surrogate marker for right ventricular dysfunction? Heart. 2000;84:409-415.
4. Vetter VL, Tanner CS, Horowitz LN. Inducible atrial flutter after the Mustard repair of complete transposition of the great arteries. Am J Cardiol. 1988;61:428-435.
5. Warnes CA, Liberthson R, Danielson GK, et al. Task force 1: The changing profile of congenital heart disease in adult life. J Am Coll Cardiol. 2001;37:1161-1198.
6. Boucher J, Therrien J, Pilote L, et al. Atrial arrhythmias in adults with congenital heart disease. Circulation 2009;120:1679-1686.
7. Kannanerkil PJ, Anderson ME, Rottman JN, et al. Frequency of late recurrence of intra-atrial reentry tachycardia after radiofrequency catheter ablation in patients with congenital heart disease. Am J Cardiol. 2003;92:879-881.
8. Moore JP, Kannankeril PJ, Fish FA. Improved efficacy of catheter ablation for atrial tachycardia in repaired congenital heart disease [Abstract]. Heart Rhythm. 2010;7(Suppl 5):S314.
9. Roos-Hesselink J, Perlroth MG, McGhie J, Spitaels S. Atrial arrhythmias in adults after repair of tetralogy of Fallot. Circulation. 1995;91:2214-2219.
10. Magnin-Poull I, De Chillou C, Miljoen H, et al. Mechanisms of right atrial tachycardia occurring later after surgical closure of atrial septal defects. J Cardiovasc Electrophysiol. 2005;16:681-687.
11. Mah DY, Alexander ME, Cecchin F, et al. The electroanatomical mechanisms of atrial tachycardia in patients with tetralogy of Fallot and double outlet right ventricle. J Cardiovasc Electrophysiol. 2011;22:1013-1017.
12. Nakagawa H, Shah N, Matsudaira K, et al. Characterization of reentrant circuit in macroreentrant right atrial tachycardia after surgical repair of congenital heart disease: Isolated channels between scars allow “focal” ablation. Circulation. 2001;103:699-709.
13. Weipert J, Boebauer C, Schreiber C, et al. Occurrence and management of atrial arrhythmia after long-term Fontan circulation. J Thorac Cardiovasc Surg. 2004;127:457-464.
14. Collins KK, Love BA, Walsh EP, et al. Location of acutely successful radiofrequency catheter ablation of intraatrial reentrant tachycardia in patients with congenital heart disease. Am J Cardiol. 2000;86:969-974.
15. Mandapati R, Walsh EP, Triedman JK. Pericaval and periannular intra-atrial reentrant tachycardia in patients with congenital heart disease. J Cardiovasc Electrophysiol. 2003;14:119-125.
16. Dave AS, Aboulhosn J, Child JS, Shivkumar K. Transconduit puncture for catheter ablation of atrial tachycardia in a patient with extracardiac Fontan palliation. Heart Rhythm. 2010;7:413-416.
17. Senning A. Surgical correction of transposition of the great vessels. Surgery. 1959;45:966.
18. Mustard WT, Keith JD, Trusler GA, et al. The surgical management of transposition of the great arteries. J Thorac Cardiovasc Surg. 1964;48:953-958.
19. Deanfield J, Camm J, Macartney F, et al. Arrhythmia and late mortality after Mustard and Senning operation for transposition of the great arteries. An eight-year prospective study. J Thorac Cardiovasc Surg. 1988;96:569-576.
20. Khairy P, Van Hare GF. Catheter ablation in transposition of the great arteries with Mustard or Senning baffles. Heart Rhythm. 2009;6:283-289.
21. El Yamen MM, Asirvatham SJ, Kapa S, et al. Methods to access the surgically excluded cavotricuspid isthmus for complete ablation of typical atrial flutter in patients with congenital heart defects. Heart Rhythm. 2009;6:949-956.