Transcatheter Repair of Fontan Baffle Stenosis and Fenestration in Two Patients Using Cook Zenith Aortic Endografts

ABSTRACT: Patients with Fontan baffles for single ventricle may have cyanosis from right-to-left shunt through leaks in the baffle or due to intentionally created fenestrations. Typically this right-to-left shunt may be addressed with catheter-based occlusion devices. However, in narrowing of the Fontan baffle, placement of occluders within the Fontan baffle may additionally narrow the pathway and is therefore undesirable. We describe 2 patients with the combination of Fontan baffle stenosis and patent fenestration treated with a Zenith abdominal aortic aneurysm endograft (Cook Medical). The covered stent graft both occluded the right-to-left shunt and eliminated the baffle stenosis. Both patients have had symptomatic improvement.

J INVASIVE CARDIOL 2012;24(2):E32-E34

Key words: Fontan, stenosis, endograft

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Fontan baffle stenosis and leaks may occur following a lateral tunnel Fontan operation and usually require surgical or catheter-based reinterventions. These complications may manifest with elevated right-sided pressures, exercise intolerance, chronic effusions, atrial arrhythmias, hypoxemia, cyanosis and paradoxical embolism.^1-5 The combination of stenosis “downstream” from the fenestration or baffle leak may significantly worsen right-to-left shunting especially with exercise because of higher pressure leading to increased right-to-left shunting. We report 2 patients with Fontan baffle stenosis and fenestrations, managed successfully using a Cook Zenith abdominal aortic aneurysm (AAA) endovascular graft. The endografts were expanded in the baffle to eliminate stenosis and exclude right-to-left shunting. 

Case Report 1. An 11-year-old male with a lateral tunnel Fontan presented with severe exercise intolerance. He was born with a diagnosis of complex heterotaxy syndrome of the asplenia type with functional single right ventricle and pulmonary atresia in the setting of dextrocardia. After initial staged procedures in early infancy, he underwent a fenestrated lateral tunnel Fontan at 3.5-years-old. At 6-years-old, his fenestration was closed with an Amplatzer septal occluder and an inferior baffle leak was closed with an Amplatzer duct occluder (ADO). Over the prior year, he complained of exercise intolerance. On walking, he became dyspneic with desaturation to 80% in less than a minute. A cardiac catheterization was performed, which showed residual flow through the Fontan fenestration and significant stenosis just superior to the fenestration (Figures 1A and 1B). The narrowing measured 9 mm with the superior and inferior baffle measuring 17 mm and 19 mm, respectively. The Fontan pressure was measured 11 mmHg without demonstrable gradient across the stenosis at rest.

A Zenith AAA iliac leg extension (Cook Medical) was chosen for the endograft with a diameter of 20 mm and a length of 55 mm to be slightly larger than the largest diameter and adequately cover the stenosis on both ends. The endograft was centered across the narrowest portion of the Fontan baffle and delivered. It was then post-dilated with an 18 mm Maxi-LD balloon (Cordis). After final dilation, the stent graft was in good position with no residual narrowing and no residual baffle leak (Figures 1C and 1D). The patient was anticoagulated with subcutaneous Enoxaparin and bridged to oral Coumadin with INR goal 1.8-2.5.

At 3-month follow-up, his exercise tolerance had improved dramatically. On a modified Bruce protocol he was able to exercise for 10.3 minutes (50th percentile for his age). His oxygen saturation at baseline was 97% and lowest saturation of 93% was recorded at maximal exercise.

Case Report 2. An 18-year-old adolescent with hypoplastic left heart syndrome status, post-staged palliation with lateral tunnel Fontan at 4-years-old, presented with worsening cyanosis. He is developmentally delayed, and his caregivers report oxygen saturations decreasing from his baseline of 91% to less than 80% at times. He underwent cardiac catheterization where a mid-baffle stenosis was found directly opposite a patent fenestration. The Fontan pressure measured 14 mmHg without demonstrable gradient across the stenosis, and an arterial saturation of 81%. An initial attempt to close the fenestration with a 4 mm Amplatzer Septal occluder resulted in a significant gradient (3 mmHg) across the baffle and the occluder was removed with a snare. The patient had several venous collaterals coil occluded and presented 6 weeks later for endograft stenting of the baffle. The narrowing measured 8 mm and the superior and inferior baffle measured 16 mm and 19 mm, respectively.

In an identical fashion to case 1, a Cook Zenith AAA iliac leg extension with 20 mm diameter and 55 mm length was deployed across the Fontan baffle and post-dilated with a 16 mm Maxi-LD balloon. Angiography then showed the graft in good position with no residual narrowing or baffle leak. The arterial saturations improved from 85% to 96%. At 1-month follow-up, he is doing well with no further desaturation episodes. Because of the anticipated difficulty of Coumadin monitoring in this patient, we chose Dabigatran at a dose of 75 mg BID (patient weight 38 Kg) for anticoagulation and he has not experienced any bleeding or thrombotic complications.

Discussion. Complications with lateral tunnel Fontan, including stenosis and leaks, are often repaired with transcatheter approaches. The intrinsic risks involved with surgical repair, including reoperative sternotomy and cardiopulmonary bypass, make surgery a less desirable option in this setting. Transcatheter approaches need to be individually tailored to account for the patient size, weight, cardiac anatomy, and the availability of a proper stent or device. Thus, the experience with such approaches is limited to a small number of case reports and case series describing the use of different stents.^6-8 Balloon expandable covered stents are less desirable in this setting as there is often a significant size discrepancy between the stenotic area and the largest baffle diameter, which can potentially result in either incomplete closure of the baffle leak or an inadvertent baffle tear. Moreover, these stents are not available in suitable sizes in the United States.

Endovascular covered stent grafts are widely used to repair abdominal and thoracic aortic aneurysms in adult patients.⁹ The Cook Zenith endograft is constructed using full-thickness woven polyester fabric sewn to a self-expanding stainless steel endoskeleton. This framework with fabric on the outside provides good graft to vessel wall apposition. The delivery system of the Cook Zenith stent offers an advantage over balloon expandable stents by enabling precise positioning and readjustment of the graft before final deployment. In addition, post-deployment, the self-expanding stent conforms to the vessel wall and selective dilation of specific areas using different balloons can then be performed. This is advantageous in the Fontan patient where the baffle is not of uniform caliber in order to minimize residual leak. While the delivery sheath size is large (16 Fr), it is routinely used for complex transcatheter procedures in older children with congenital heart disease. This size sheath is easily introduced with a Seldinger technique and complications due to a large sheath in the femoral vein are uncommon.

In the U.S., other commercially available aortic endografts include the Gore Excluder, the Medtronic Endurant, and the Endologix Powerlink. Our decision to use the Cook Zenith endograft was influenced by the following factors. The Gore Excluder and Medtronic Endurant iliac leg extensions come in the shortest lengths of 70 mm and 82 mm, respectively. These were unsuitable for our patients as the stents would extend on either end into the pulmonary artery or the hepatic veins. The Endologix Powerlink iliac leg extension is available in 55 mm length, but the stent is supported with a dense cobalt chromium alloy endoskeleton. We were concerned that this might be a higher risk for thrombosis in the low-velocity venous system. 

Conclusion

Covered endovascular stent therapy may offer a good solution to treat Fontan baffle stenosis especially when they are complicated by leaks.

References

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From the Departments of ¹Pediatric Cardiology and ²Surgery, Mount Sinai School of Medicine, New York, New York.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.
Manuscript submitted June 21, 2011, provisional acceptance given July 18, 2011, final version accepted July 27, 2011.
Address for correspondence: Barry Love, MD, Mount Sinai Medical Center, One Gustave L. Levy Place, Box 1201, New York, NY 10029. Email: barry.love@mssm.edu