Ablation of Atrial Fibrillation in a Patient with a Percutaneous Septal Occluder Device

Patients with atrial septal defect (ASD) have an increase in the incidence of atrial arrhythmias that persist after surgical or percutaneous septal closure. Adult cardiologists are faced with treating atrial flutter (AFL) and atrial fibrillation (AF) in this population who often do not respond well to medical treatment.

Catheter ablation has emerged as a class I indication to treat symptomatic drug-refractory paroxysmal AF. However, left atrium access is challenging after ASD closure, and usually delays or precludes this population from having an ablation.

I report a case of a patient with symptomatic paroxysmal AF refractory to three antiarrhythmic drugs with an ASD percutaneously closed 10 years ago who underwent successful catheter ablation. The potential pitfalls and tricks of this case are reviewed.

Case Description

A 54-year-old male had recurrent episodes of paroxysmal AF for the last two years. He was electrically cardioverted twice within 48 hours of initiation, and lately his episodes were two or three times a week. He failed propafenone, flecainide and dronedarone. Because of an atrial septal closure device placed for atrial septum secundum defect 10 years ago, he was started on amiodarone and not considered for catheter ablation. Later, this drug was stopped because of hypothyroidism and failure to control his symptoms. He was then referred for catheter ablation. He was anticoagulated on warfarin, and continued it throughout the procedure with a target INR of 2.5–3.0.

Ostium Septum Secundum

In 4 of 100,000 newborns, an error in the heart developmental process will result in a defect in the wall separating the two atria, an ASD.1 The atrial septum secundum is the most common type of septal defect. It usually arises from inadequate growth of the septum secundum to close the septum primum, resulting in an orifice in the middle of both atria (Figure 1).

Most frequently, adult patients present with dyspnea on exertion, but de novo atrial arrhythmias or syncope may be the first manifestation of the disease.¹ Rarely, a patient with ASD presents with stroke due to paradoxical embolization. Late follow up (>25 years) in patients who have undergone surgical or percutaneous closure after childhood reported an incidence of atrial arrhythmias up to 41 to 59 percent.²

The pathophysiology of the arrhythmias appears to be related to left atrial dilation that persists after closure. Several studies showed that older age (>40 years) at the time of surgery, the presence of preoperative atrial flutter or fibrillation, and the presence of postoperative atrial flutter or fibrillation or junctional rhythm were predictive of late postoperative AFL or AF.³

When there is evidence of symptoms or echocardiographic right-sided cardiac volume loading without pulmonary hypertension, surgical or percutaneous closure is indicated.

AMPLATZER Device

The AMPLATZER septal occluder (AGA Medical Corporation, now part of St. Jude Medical) is a self-expandable, double-disc device made from a nitinol wire mesh. The two discs are linked together by a short connecting waist corresponding to the size of the ASD (Figure 2). It is delivered percutaneously through a 6–12 Fr catheter, and there should be a distance >5 mm from the margins of the defect to the mitral valve, to the right upper pulmonary vein, and to the inferior and superior vena cava, so that the closure device does not impinge upon the SVC, IVC, or the tricuspid or mitral valves.

ASA is indicated for six months post procedure at a dose of 3–5 mg per kg to a max of 150 mg day to prevent thrombi formation while device endothelialization occurs.

The success and safety of transcatheter techniques have significantly increased the number of percutaneous closure procedures, becoming the preferred mode of ASD repair in many centers.

Ablation of Atrial Fibrillation

Procedure

An anesthesiologist was in charge of inducing general anesthesia with propofol (2 mg/kg) and fentanyl (1–2 kg/kg), followed by a neuromuscular blocking agent (rocuronium 0.6–1 mg/kg) and by endotracheal intubation.

Right internal jugular access was obtained to place a 6 Fr decapolar catheter into the coronary sinus. A small portion of the native septum was identified with intracardiac ultrasound (ViewFlex^™ Intracardiac Ultrasound catheter, St. Jude Medical, St. Paul, MN) as the preferred location to cross to the left atrium (LA). One single transseptal puncture was done with exchanges of a circular catheter (Reflexion Spiral^™, St. Jude Medical) and the ablation catheter through the same sheath to ablate AF.

Left atrial access was obtained with a deflectable 8.5 Fr sheath (Agilis NxT, St. Jude Medical). The whole apparatus, sheath, dilator and Brockenbrough^® needle (Medtronic, Minneapolis, MN) was gently pulled down under ICE visualization, on left anterior view until the tip of the dilator was below the AMPLATZER aiming toward the LA. Heparin 5000 units bolus was administered prior to crossing to the LA. Septal tenting was done inferiorly to the AMPLATZER through the native septum (Figure 3). The Brockenbrough needle failed to cross the septum. A surgical electrocautery pen was placed on the proximal hub of the needle during tenting of the septum, with the generator programmed to 30 W in the cut mode. After 2–4 seconds of radiofrequency energy application, the needle entered the LA with ICE and left atrial pressure confirmation. Then the dilator was advanced over the needle, and the sheath was advanced over the dilator to finally reach the left atrium (Figure 4). At this stage, the needle and dilator were removed, and the sheath was accurately aspirated and flushed with heparinized saline. Heparin was administered to maintain an ACT of >350 seconds.

Manipulation within the LA was relatively easy, facilitated by the use of a deflectable sheath despite a low puncture site. There was a common left antrum and two independent right pulmonary veins (PV). Ablation was done in a power mode with a 4 mm tip ablation catheter (Safire BLU, St. Jude Medical) with the RF generator set at 30 watts maximum. An esophageal probe was used to monitor esophageal temperature during ablation.

Pulmonary Vein Atrial Tachycardia

Left atrial and PV geometry was built with EnSite NavX (St. Jude Medical) by roving the circular catheter within the LA. The CS catheter was used as a reference.

Spontaneous initiation and termination of atrial tachycardia that degenerated into AF was observed on several occasions. P wave polarity was positive in inferior leads and precordial leads, negative in AVL and I (Figure 5). Placement of the circular catheter in the antrum of the left upper PV recorded one of these episodes (Figure 5). Intracardiac electrograms at that site showed an atrial tachycardia, cycle length=110 ms, slightly irregular prior to initiation of atrial fibrillation. The ablation catheter was inserted after removal of the circular catheter through the same deflectable sheath. PV isolation was confirmed by elimination of PV potentials (Figure 6) on the circular catheter at the PV antrum. All the PVs were electrically isolated. Cavotricuspid isthmus ablation was performed because of documentation of typical flutter.

No further arrhythmias were observed after isolation of the left pulmonary vein. Isoproterenol was administered up to 4 micrograms/min without provocation of any arrhythmias.

Follow up

Coumadin was continued for two months post procedure. His CHADS2 score=1 and CHA2DS2-VASc Score=1, thus, oral anticoagulation was recommended over aspirin according to the AF guidelines. He was switched over to dabigatran 150 mg bid afterwards. He has been free of any arrhythmias for seven months, with a heart monitor every three months, on no antiarrhythmic drugs. There was no residual atrial shunt on an echocardiogram performed three months post procedure.

Conclusions

Catheter ablation usually is avoided or delayed in patients with ASD closure devices due to the higher perceived risks and difficulty of performing transseptal puncture in the presence of a septal device. When the following precautions are met, the procedure is safe and effective:

1. Due to the lack of tactile sensation of engaging the fossa ovalis during pulling down the transseptal apparatus when a septal closure device is present, use of intracardiac or transesophageal echo is essential to cross safely to the LA.
2. It is desirable to target the native atrial septum if possible. When no native septum is identified by ICE or a double transseptal is required, a puncture can be safely done by crossing the AMPLATZER with the Brockenbrough needle and upsizing with the aim of a dilator before introducing a sheath in the LA. The latter usually takes longer than crossing the native septum, and it is has been shown to be safe without damaging the device or leaving a residual shunt.⁴
3. Because access of the LA is not through its thinner portion, i.e., the fossa ovalis, radiofrequency energy-assisted transseptal puncture is usually required.  
4. A deflectable sheath may enhance catheter manipulation in the LA, though is not mandatory.

References

1. Sommer RJ, Hijazi ZM, Rhodes JF Jr. Pathophysiology of congenital heart disease in the adult: part I: Shunt lesions. Circulation 2008;117:1090–1099.
2. Spies C, Khandelwal A, Timmermanns I, Schräder R. Incidence of atrial fibrillation following transcatheter closure of atrial septal defects in adults. Am J Cardiol 2008;102:902–906.
3. Gatzoulis MA, Freeman MA, Siu SC, et al. Atrial arrhythmia after surgical closure of atrial defects in adults. N Engl J Med 1999;340:839–846.
4. Santangeli P, Di Biase L, Burkhardt JD, et al. Transseptal access and atrial fibrillation ablation guided by intracardiac echocardiography in patients with atrial septal closure devices. Heart Rhythm 2011;8:1669–1675.