Complete Closure of Long Tunnel Patent Foramen Ovale Using the CardioSeal Device

Introduction

Patent foramen ovale (PFO) is more prevalent in patients with cryptogenic stroke (CS) than in individuals with a stroke of known cause, suggesting that “paradoxical embolus” (i.e., the migration of a venous thrombus across the PFO to the systemic circulation) may be the etiology of stroke in some patients.¹ Currently, secondary prevention of recurrent CS in patients with PFO includes medical therapy with oral antiplatelet and anticoagulant medications or PFO closure (percutaneous or surgical). The majority of the PFO closures are now done percutaneously due to the ease of the technique and the high success rates achieved. Certain anatomical aspects of the PFO make delivering the occluder device and obtaining adequate disk apposition more challenging. We report a case of a PFO with long tunnel closed using the transseptal approach after a failed attempt at device deployment through the PFO.

Case Report

A 38-year-old male presented in May 2005 to the emergency room complaining of a sudden onset left arm weakness and numbness, and left lower extremity numbness. His symptoms improved over a period of two hours, leading to complete recovery of function and sensation. He reported that he had several similar but somewhat milder episodes over the past 3 months. The work-up included an MRI of the brain, an MRA of the neck and head CT angio, which were unremarkable. A transesophageal echocardiogram (TEE) revealed a small PFO with right-to-left shunting on the bubble study with Valsalva maneuver. There was no evidence of left atrial or left atrial appendage thrombus. The left ventricular systolic function was normal, with normal valvular function and physiology. The lower extremities’ Doppler examination with impedance plethysmography was negative. The patient was diagnosed with transient ischemic attack (TIA) secondary to PFO. Due to work restrictions on taking oral anticoagulants and the fact that he had extensive bruising with ASA and clopidogrel, he was referred for PFO closure. The IntraCardiac Echocardiogram (ICE) (AcuNav, Siemens Medical Solutions, Malvern, Pennsylvania) revealed a long tunnel PFO (about 15 mm), which was confirmed with the sizing balloon.

Initially we felt that a large 33-mm CardioSeal closure device (NMT Medical, Boston, Massachusetts) would be adequate to close the defect. Upon deploying the device, we had excellent apposition over the left atrial side; however, the right atrial umbrella clumped inside the tunnel. Despite multiple manipulations, we were not able to free up the device adequately from the tunnel to close the flap. Therefore, it was decided to remove the device and abort the procedure. Immediately after the device removal, the patient was noted to have slurred speech, and left upper and lower extremity weakness. The symptoms improved gradually and completely resolved in 24 hours; however, an MRI revealed a small infarct involving the right hypothalamus region.

The following morning, the patient suffered a second TIA event, which resolved in 10 minutes. Considering the clustering of the recurrent TIA episodes, our management options were closing the PFO using a transseptal technique versus surgical closure. We felt confident that we could close the PFO delivering the device transseptally, and after an informative discussion with the patient about the risks and benefit of both alternatives, it was decided to proceed with percutaneous closure. Under ICE guidance, the septum primum was punctured using a Brockenbrough needle and transseptal sheath. Then the transseptal sheath was exchanged for the CardioSeal sheath over a wire placed in the left superior pulmonary vein. The CardioSeal device was advanced and deployed with good fluoroscopic results. ICE confirmed adequate sandwiching of the left and right atrial disks across the atrial septum, occluding the PFO. The patient was discharged the following morning, and at two-month follow up, he was asymptomatic without any further TIA recurrences. Follow-up TEE with contrast study showed no residual shunt.

Discussion

Approximately 25–40% of strokes have no apparent cause and are termed “cryptogenic.”2 A PFO is found in 44–66% of such patients, compared with only 9–27% in the control group.^2,3 Paradoxical embolization through the PFO, although it remains unproven, is the presumed pathophysiologic mechanism. The most appropriate secondary prevention strategy in survivors of cryptogenic stroke (CS) or transient ischemic attack with PFO is still controversial. A conservative approach of long-term medical therapy with antiplatelet agents or oral anticoagulants has been used. Alternatively, surgical closure of patent foramen ovale can be performed with minimal morbidity and mortality, and has been used in high-risk patients, or those intolerant to antiplatelet therapies. It represents an effective means of eliminating PFO as a potential risk for stroke recurrence, with limited supportive data. Reported ischemic neurologic event recurrence rates of 4–17%/year are likely to be distorted by limited enrollment and the small size of the studies conducted.^4,5

Percutaneous PFO closure, first performed in 1989, has evolved in the past decade as a low-risk alternative therapeutic option.⁶ Despite the lack of large-scale randomized studies, case series have suggested a significant risk of stroke/TIA recurrence (4–20%/year) for patients with CS and PFO using medical treatment.^7,8 Meta-analysis of nonrandomized studies of PFO-associated stroke demonstrated that warfarin was superior to antiplatelet therapy, and that surgical closure and anticoagulation were associated with similar outcome.⁹ Windecker et al.¹⁰ reported that percutaneous PFO closure devices, (compared with medical therapy), resulted in a borderline, statistically significant reduction in the combined endpoint of death, stroke or transient ischemic attack after a mean follow up of 2.3 years (8.5% versus 24.3%, p = .05) in a retrospective series of 308 patients with PFO and cryptogenic stroke. In a recent systemic review of studies involving 1355 stroke patients treated with transcatheter PFO closure, and 895 medically-treated patients, the one-year rates of recurrent neurologic thromboembolism ranged from 0–4.9% in PFO closure group and 3.8–12.0% in the medical therapy group. The authors estimated, after adjusting for attributable risk due to the higher prevalence of diabetes mellitus and smoking in medically treated patients with PFO, that after the first year of follow up, for every 23 patients who had their PFO closed percutaneously, one stroke or TIA was prevented, compared to use of medical treatment.^6,11

Studies have shown over 95% closure success rate using a variety of devices.¹² In the United States, only two percutaneous closure devices are approved by the Food and Drug Administration under the Humanitarian Device Exemption: the CardioSeal septal occlusion system (NMTI Medical, Boston, Massachusetts) and the Amplatzer occluder (AGA Medical Corp. Golden Valley, Minnesota). Despite the reported simplicity of the technique involved in placing the device, occasionally structural variations of the atrial septum increase the difficulty encountered during the device deployment. These variations include long tunnel, thick septum secundum or the presence of multiple fenestrations. In our patient, the presence of a long tunnel precluded full deployment of the umbrella on the right side of the atrial septum.

We opted to deliver the CardioSeal device through a transseptal approach and “sandwich” the septum primum and septum secundum together. Reports describing the efficacy of transseptal closures for PFOs with long tunnel have been mostly anecdotal. The largest published report involved 12 such patients. The authors reported a relatively low success rate (40%) in achieving complete closure at 6-month TEE follow-up.¹³ Besides a simple transseptal puncture, few other techniques have been proposed including using a left atrial to right atrial balloon pull-through to make the septum primum incompetent to assist in the closure. This technique was associated with a high initial success rate of achieving adequate device positioning and few residual shunts (16%) in a small study.¹⁴ An Amplatzer PFO occluder, which conforms to long tunnel-shaped PFO because of the twisted neck connecting the two disks, is another option when available,¹⁵ but there is no large-scale study examining its efficacy under these conditions.

Conclusion

Our case illustrates that a long-tunnel PFO can increase the difficulty of the occluder device deployment. Delivering the device through a transseptal approach, though relatively more time-consuming and requiring more technical skill from the operator, is a safe and viable alternative that may lead to complete PFO closure.