Catheter ablation of supraventricular tachycardia in the transplanted heart: a case series and literature review

Management of Arrhythmias After Heart Transplant: Current State and Considerations for Future Research

Orthotropic heart transplantation remains the most effective therapy for patients with end-stage heart failure, with a median survival of ≈13 years. Yet, a number of complications are observed after orthotropic heart transplantation, including atrial and ventricular arrhythmias. Several factors contribute to arrhythmias, such as autonomic denervation, effect of the surgical technique, acute and chronic rejection, and transplant vasculopathy among others. To minimize risk of future arrhythmias, the bicaval technique and minimizing ischemic time are current surgical standards. Sinus node dysfunction is the most common indication for early (within 30 days) pacemaker implantation, whereas atrioventricular block incidence increases as time from transplant increases. Atrial fibrillation can occur in the first few weeks following transplantation but is uncommon in the long term unless secondary to a precipitant such as acute rejection. The most common atrial arrhythmias are atrial flutters, which are mainly typical, but atypical circuits can be observed such as those that involve the remnant donor atrium in regions immediately adjacent to the atrioatrial anastomosis suture line. Choosing the appropriate pharmacological therapy requires careful consideration due to the potential interaction with immunosuppressive agents. Despite historical concerns, adenosine is effective and safe at reduced doses if administered under cardiac monitoring. Catheter ablation has emerged as an effective treatment strategy for symptomatic supraventricular tachycardias, including ablation of atypical flutter circuits. Cardiac allograft vasculopathy is an important risk factor for sudden cardiac death, yet the role of prophylactic implantable cardioverter-defibrillator implant for sudden death prevention is unclear. Current indications for implantable cardioverter-defibrillator implantation are as in the nontransplant population. A number of questions for future research are posed.

Radiofrequency ablation of supraventricular arrhythmias after orthotopic heart transplantation: Long-term follow-up of a single-center experience

BACKGROUND

Supraventricular arrhythmias (SVAs), commonly managed with radiofrequency ablation (RFA), may occur after orthotopic heart transplantation (OHT).

METHODS

We retrospectively assessed 514 consecutive patients (pts.) undergoing OHT between January 1990 and July 2016 in a single-center. Patients with SVAs managed with RFA were included. Mechanisms of genesis of SVAs, association with surgical techniques and outcomes, were analyzed.

RESULTS

Of 514 pts undergoing OHT, 53% (272 pts.) were managed with bicaval (BC) technique and 47% (242 pts.) with biatrial (BA) technique. Mean follow-up 10 ± 8.4 years. Nine pts. (1.7%) developed SVA requiring RFA. The BC technique was performed in 4 pts., 3 pts. presented cavotricuspid isthmus-dependent atrial flutter (CTI AFL), and 1 pt. double loop AFL. Five pts. were managed with BA technique, 4 pts. presented CTI AFL, and 1 pt. atrial tachycardia (AT). Mean time between OHT and SVA occurrence was 6.6 ± 5.5 years. The procedure was successful in 89% (8 pts.). Arrhythmia recurrence was seen in 3 pts (37%), all with BA technique.

CONCLUSION

Supraventricular arrhythmias in heart transplantation may be associated with the surgical scar. Identifying the mechanism is vital to choose the appropriate treatment with radiofrequency ablation.

Atrial Tachyarrhythmias After Cardiac Transplantation

Cardiac transplant recipients demonstrate a unique substrate for atrial tachyarrhythmias owing to the surgical techniques involved. Surgical modification of the atria during transplant surgery has both proarrhythmic and antiarrhythmic effects detailed in this paper. Cavotricuspid isthmus-dependent right atrial flutter is the most common arrhythmia identified. Atrial fibrillation is uncommon owing to obligatory surgical pulmonary vein isolation. Donor hearts can also contain pre-existing accessory pathways or dual AV nodal physiology causing supraventricular tachycardia for which adenosine treatment is not recommended, but catheter ablation is curable.

Supraventricular arrhythmias late after orthotopic cardiac transplantation: electrocardiographic and electrophysiological characterization and radiofrequency ablation

AIMS

Cardiac transplantation (CTX) is an effective treatment for end-stage heart disease. Cardiac arrhythmias are increasingly recognized and associated with significant morbidity and mortality. We aim to describe the clinical and electrophysiological characteristics of patients with atrial arrhythmias occurring late after CTX.

METHODS AND RESULTS

Sixteen patients with prior CTX who presented with late atrial arrhythmias for electrophysiological studies (EPS) were identified at two cardiac transplant centres. Among 859 patients, 16 (mean age 52 ± 14 years, 11 of 16 were men) patients underwent EPS for atrial arrhythmias presenting 8.6 ± 5.7 years following CTX. Among 16 patients, 14 underwent cardiac alone and 2 included lung transplantation. There were no cases of cardiac rejection. Arrhythmias were due to counterclockwise cavotricuspid-dependent atrial flutter (AFL) in 10 of 16, atrial tachycardia (AT) in 6 (1 patient had AFL and AT), and 1 due to atrioventricular nodal re-entrant tachycardia. Recipient-donor atrial electrical connection was seen in two of six AT and in no cases of AFL. In two cases, a focal AT was mapped to the remnant atrium conducting 2 : 1 or at variable block to the donor atrium. In four cases a focal/micro re-entrant AT originated within the vicinity of the interatrial suture scar. All cases were successfully ablated with radiofrequency energy; however, one case of AFL required a repeat ablation. Patients remained free of arrhythmia at 34 ± 15 months post-ablation.

CONCLUSION

Typical AFL and AT are the most frequent supraventricular arrhythmias occurring late following CTX. Focal ATs may originate in low-voltage or border zones immediately adjacent to the atrio-atrial anastomosis. Radiofrequency ablation is an effective treatment strategy with high long-term success.

Atrial flutter after heart transplantation: mechanism and catheter ablation

BACKGROUND

Atrial flutter is a frequent arrhythmia after heart transplantation, but little is known about its mechanism and treatment. We report the results of an electrophysiologic study in patients with atrial flutter after orthotopic heart transplantation, describing its mechanism and demonstrating the acute and long-term efficacy of catheter ablation for treating this arrhythmia.

METHODS

We included 14 patients with symptomatic atrial flutter after orthotopic heart transplantation. All of them underwent an electrophysiologic study to determine the mechanism of the arrhythmia and catheter ablation when possible.

RESULTS

Counterclockwise right atrial circuit around the tricuspid annulus involving the cavotricuspid isthmus was demonstrated in 13 patients (86%). Catheter ablation of the isthmus was performed with good acute results in all but 1. During a mean follow-up of 24 ± 17 months, recurrent atrial flutter was documented in 3 patients and atrial fibrillation in 2. In another patient, we demonstrated a left atrial origin.

CONCLUSIONS

The most common mechanism of atrial flutter in heart transplant recipients is a counterclockwise circuit around the tricuspid annulus involving the cavotricuspid isthmus. Catheter ablation of the isthmus between tricuspid annulus and posterior atrial suture line represents an effective treatment in these patients. This condition may be avoided by changing the surgical technique to a bicaval anastomosis.

Reversible loss of pre-excitation as a sign of acute cardiac rejection

A 50-year-old woman presented with signs of mild heart failure 16 months after orthotopic heart transplantation. Cardiac biopsy revealed ISHLT Grade 2R rejection, which was treated with corticosteroids. Electrocardiograms (ECGs) after transplantation showed a pre-excitation pattern; the presenting ECG showed complete loss of pre-excitation, which returned fully within 7 days of steroid therapy. Intermittent pre-excitation had been present for 4 weeks prior to any other clinical sign of rejection. Accessory pathways can display reversible loss of function during acute cellular rejection, and this may precede other clinical signs. This rare but significant finding may have clinical relevance to other transplanted patients with pre-excitation.

Electroanatomical mapping and radiofrequency catheter ablation of atrial tachycardia originating from the donor heart after orthotopic heart transplantation in a child

A 15-year-old boy who had been given an orthotopic heart transplant 12 years earlier underwent radiofrequency ablation after 14 months of tachycardia. At the time of the procedure, the patient presented moderate signs of heart failure and tachycardia-induced cardiomyopathy. During electroanatomical mapping we identified a focal atrial tachycardia with origin in the donor right atrium and bi-directional atrio-atrial conduction. After successful focal ablation the patient had two alternating atrial activation patterns, representing the recipient and the donor heart sinus rhythm. Two months after the ablation heart failure symptoms were in regress, and the patient was still in sinus rhythm.

Supraventricular tachycardia after orthotopic cardiac transplantation

OBJECTIVES

The purpose of this study was to define the incidence, mechanisms, and management, including catheter ablation, of supraventricular tachycardia (SVT) in a large series of patients after orthotopic heart transplantation (OHT).

BACKGROUND

Supraventricular arrhythmias are frequently encountered after OHT, but their characteristics in this population have not been well established.

METHODS

We analyzed the incidence, clinical course, and management of SVTs in a cohort of 729 adult patients who underwent OHT. Furthermore, the mechanisms of arrhythmias among the patients referred for electrophysiological study (EPS) and ablation were also characterized.

RESULTS

The most common arrhythmia was atrial flutter, which occurred in 9% of this cohort. Persistent or paroxysmal atrial fibrillation occurred in 7%, the majority (57%) in the perioperative period. Persistent or paroxysmal atrial fibrillation was observed in OHT patients, beyond the post-operative period, only in the presence of rejection or transplant vasculopathy. Other persistent or paroxysmal SVTs were seen in 47 stable OHT patients (7%). Of these, 24 patients (4%) underwent EPS. Accessory and dual atrioventricular nodal pathways in the donor heart caused SVT in 3 patients. Macro-reentrant atrial tachycardia was seen in 7 patients, and isthmus-dependent atrial flutter occurred in 14 patients.

CONCLUSIONS

The majority of SVTs in stable OHT patients can be attributed to macro-reentrant tachycardias (flutter and scar reentry). Catheter ablation is effective in management of these SVTs. Atrial fibrillation was never encountered in stable patients in our series, and its occurrence should prompt an evaluation for acute rejection and/or vasculopathy.

Recipient atrial flutter masquerading as donor flutter in a heart transplant recipient

Atrial flutter is common after orthotopic heart transplantation. We present the case of a patient who presented with atrial flutter on 12-lead electrocardiogram. On invasive electrophysiologic study, the donor heart was found to be in sinus rhythm and the recipient atrium was in flutter, which was dissociated from the donor.

Radio-Frequency Catheter Ablation of Accessory Pathway Mediated Tachycardia in a Child After Orthotopic Heart Transplantation

Successful radio-frequency catheter ablation of accessory pathway mediated supraventricular tachycardia in the transplanted heart has been reported sporadically in adults, but has not been reported in children. This is the first report of a child having received a donor heart with manifest pre-excitation and who subsequently underwent successful radio-frequency ablation of the accessory pathway.

Mechanism of Atrial Flutter Occurring Late After Orthotopic Heart Transplantation with Atrio-atrial Anastomosis

OBJECTIVE

We sought to better define the electrophysiologic mechanism of atrial flutter in patients after heart transplantation.

BACKGROUND

Atrial flutter is a recognized problem in the post-cardiac transplant population. The electrophysiologic basis of atrial flutter in this patient population is not completely understood.

METHODS

Six patients with cardiac allografts and symptoms related to recurrent atrial flutter underwent diagnostic electrophysiologic study with electroanatomic mapping and radiofrequency catheter ablation. Comparison was made with a control non-transplant population of 11 patients with typical counterclockwise right atrial flutter.

RESULTS

In each case, mapping showed typical counterclockwise activation of the donor-derived portion of the right atrium, with concealed entrainment shown upon pacing in the cavotricuspid isthmus (CTI). The anastomotic suture line of the atrio-atrial anastomosis formed the posterior barrier of the reentrant circuit. Ablation of the electrically active, donor-derived portion of the CTI was sufficient to terminate atrial flutter and render it noninducible. Comparison with the control population showed that the electrically active portion of the CTI was significantly shorter in patients with transplant-associated flutter and that ablation was accomplished with the same or fewer radiofrequency lesions.

CONCLUSIONS

Atrial flutter in cardiac transplant recipients is a form of typical counterclockwise, isthmus-dependent flutter in which the atrio-atrial anastomotic suture line forms the posterior barrier of the reentrant circuit. Ablation in the donor-derived portion of the CTI is sufficient to create bidirectional conduction block and eliminate this arrhythmia. Ablation or surgical division of the donor CTI at the time of transplantation could prevent this arrhythmia.

Ablation of atrial tachycardia after surgery for congenital and acquired heart disease using an electroanatomic mapping system: Which circuits to expect in which substrate?

OBJECTIVES

The purpose of this study was to compare atrial tachycardia circuits after a range of cardiac operations.

BACKGROUND

Knowledge of circuits occurring in a given postsurgical substrate should help to ablate these challenging tachycardias and develop potential preventive strategies.

METHODS

We analyzed tachycardia circuits in 83 consecutive patients (60 males; median age 47 years, range 9-73) after atrial incisions undergoing ablation of atrial tachycardias. A combined strategy of electroanatomic (CARTO) and entrainment mapping was used. Fifty-two patients (63%) underwent operation for congenital and 31 (37%) for acquired heart disease. Patients were divided into subgroups based on the intervention performed in the atria: right lateral atriotomy (39 patients), left atrial (11) and superior transseptal (10) approach to the mitral valve, biatrial heart transplantation (8), Mustard (8) and Fontan (4) procedure, and other interventions (3).

RESULTS

Most of the 119 tachycardias mapped were isthmus-dependent atrial flutter (66) and incisional tachycardia (30). Isthmus-dependent atrial flutter was the most frequent arrhythmia in all subgroups except for Fontan patients, in whom incisional tachycardia was most frequent. The distribution of tachycardia circuits did not differ significantly among groups.

CONCLUSIONS

The observed circuits did not differ among the postsurgical substrates. Isthmus-dependent atrial flutter should be the first circuit considered in patients after atrial incisions.

Electroanatomical Mapping and Radiofrequency Catheter Ablation of Atrial Tachycardia Originating from the Recipient Heart with Recipient-to-Donor Atrio-Atrial Conduction After Orthotopic Heart Transplantation

Atrial tachycardias resulting from recipient-to-donor atrio-atrial conduction after orthotopic heart transplantation are difficult to treat. We present two patients in whom atrial tachycardia originating in the recipient heart were successfully treated by radiofrequency ablation guided by electroanatomical CARTO mapping system. These cases illustrate that such atrial tachycardia are curable by radiofrequency ablation. Electroanatomical CARTO mapping is useful in identifying the site of origin of the tachycardia and the atrio-atrial conduction sites.

Catheter Ablation of Atrial Flutter after Orthotopic Heart Transplantation

INTRODUCTION

Atrial arrhythmias, including atrial flutter, are common in orthotopic heart transplant recipients. However, only a small number of individual case reports describe the electrical circuit and catheter ablation of atrial flutter after heart transplantation.

METHODS AND RESULTS

Detailed electrophysiologic evaluation and radiofrequency ablation of atrial flutter were performed in three patients after orthotopic heart transplantation. All cases involved a counterclockwise flutter circuit around the tricuspid annulus. All were successfully ablated at the isthmus between the tricuspid valve and the atrial anastomosis adjacent to the inferior vena cava.

CONCLUSION

Atrial flutter involving a counterclockwise circuit around the tricuspid annulus is common in the heart transplant population. Based on the patients described in this study and other cases reported in the literature, this arrhythmia often is treated successfully by ablation of the isthmus between the tricuspid valve and the atrial anastomosis near the inferior vena cava.