Introduction
Maintaining Fontan pathway patency is essential for preserving haemodynamics in univentricular circulation. Stenosis of the Fontan conduit can develop due to growth-related stretching, graft calcification, or intimal lining formation, leading to power loss. Reference Lee, Lee and Chiu1 These structural changes contribute to power loss within the Fontan circuit, making stent implantation essential for restoring conduit diameter and optimizing blood flow. Reference Moszura, Góreczny and Dryżek2 This report describes a patient with arterial desaturation post-stenting, worsening in the upright position, suggesting platypnea-orthodeoxia syndrome and requiring further investigation.
Case description
A 16-year-old female with pulmonary valve atresia and right ventricular hypoplasia, who had undergone a Fontan procedure with an intracardiac tunnel and a patent fenestration, was admitted for routine follow-up. On admission, she weighed 47.5 kg, was 152 cm tall, and had an oxygen saturation of 84% and hepatomegaly. She reported fatigue, and liver elastography indicated advanced fibrosis. Echocardiography showed significant Fontan tunnel narrowing (Figure 1a), prompting referral for cardiac catheterisation. Despite previous reports of femoral vessel occlusion, vascular access was successfully obtained via the right femoral artery and stenotic left femoral vein. Baseline haemodynamic assessment revealed an inferior vena cava pressure of 12 mmHg and mean pulmonary artery pressure of 11 mmHg. Angiography confirmed severe narrowing (Figure 2a). To reduce the size of the delivery sheath and preserve fenestration patency, a 45 mm uncovered Cheatham Platinum stent (CP, NuMed) mounted on a 16 mm balloon in balloon catheter (NuMed) was implanted and redilated with an Atlas 20 x 40 mm balloon (Bard). Angiography post-implantation confirmed full coverage of the stenotic segment with a patent fenestration and no contrast extravasation (Figure 2b). Additionally, a large venovenous fistula in the left venous angle was occluded.
Figure 1. Echocardiographic findings. a. Subcostal view showing significant narrowing of the Fontan tunnel (blue arrow). b. Subcostal view demonstrating an unobstructed Fontan tunnel following stent implantation (blue arrow). c. Four-chamber view illustrating normal flow through the fenestration (white arrow) before first catheterization. d. Four-chamber view after first catheterization depicting flow through the fenestration (white arrow) with additional excessive flow from the tunnel to the left atrium (black arrowheads).
Figure 2. Angiography findings. a. Significant narrowing of the tunnel. The tunnel measured 25 mm in the proximal segment, 12.1 mm in the middle portion (blue arrow), and 18.9 mm distally. Patent fenestration (white arrow). b. Post-deployment angiography showing complete coverage of the narrowed segment (blue arrow), with a minimum diameter of 19.2 mm, and preservation of fenestration patency (white arrow). No contrast extravasation observed. c. Contrast filling the entire right atrium immediately after contrast administration (black arrows) confirming a significant baffle leak. d. Post-deployment of the covered stent. Contrast is present only in the lower part of the right atrium, at the level of the fenestration (black arrows).
Immediately after the procedure, oxygen saturation improved to 90%, and echocardiography showed normal cardiac function with adequate Fontan tunnel flow. However, the following day, after mobilisation, the patient’s condition deteriorated, with oxygen saturation dropping to 82%. Chest radiography ruled out pulmonary pathology. In the following days, oxygen saturation continued to decline to 78% in the supine position and 65% upright, a finding consistent with platypnea-orthodeoxia syndrome.
Repeat echocardiography suggested a new baffle leak (Figure 1c, d). CT angiography was performed; however, it was inconclusive due to stent artefacts and a patent fenestration. Final angiographies from the heart catheterisation procedure were reviewed, and a small, right-to-left contrast flow, beyond the fenestration, could not be ruled out.. Given the patient’s history and clinical presentation, a second catheterisation was performed, revealing an initial aortic oxygen saturation of 83%. Vascular access was achieved via the right internal jugular vein, avoiding the recently accessed stenotic femoral vein. Angiography revealed significant intracardiac patch dehiscence (Figure 2c, Supplementary Video 2). A 4 Fr Berenstein catheter was advanced across the previously stented tunnel, significantly higher than the fenestration, to the right atrium (Supplementary Video 2). The short sheath was exchanged for a 30 cm 12 Fr sheath, and a covered 45 mm CP stent mounted on a 20 mm BIB balloon was implanted at the site of the previous stent to seal the leak. Control angiography confirmed successful defect sealing (Figure 2d, Supplementary Video 2) while preserving fenestration patency. The procedure was complication-free. Arterial oxygen saturation stabilised at 92%. A 24-hour heparin infusion was initiated, followed by a non-vitamin K antagonist oral anticoagulant for six months per institutional protocol. Post-procedure chest radiography confirmed stable stent positioning, and echocardiography demonstrated satisfactory results (Figure 1b). The patient’s condition improved, with oxygen saturation stabilising at 89% in all positions. At three-month follow-up, she reported no complaints, and her exercise tolerance significantly improved.
Discussion
Fontan circulation relies on passive blood flow, and conduit narrowing can cause power loss, exacerbating hepatic fibrosis and limiting exercise capacity. Although indications for Fontan conduit stenting remain debated, many consider a 25% reduction in diameter significant, even without a pressure gradient. Reference Jalal, Mets and Lee3 In this case, the narrowing approached 50%, justifying stent placement.
Both bare-metal and covered stents are used for Fontan tunnels. Reference Hagler, Tajiri and Mets4 Here, a bare-metal stent was selected due to limited vascular access and the need to maintain fenestration patency. No immediate baffle leak was observed post-procedure, but as the patient’s desaturation worsened and platypnea– orthodeoxia syndrome appeared, further diagnostic steps were taken. Few reports exist describing platypnea–orthodeoxia syndrome in post-Fontan patients; those published have most involved ventilation-perfusion mismatch Reference Tajiri, Lee and Chiu5 or venovenous malformations. Reference Lee and Chiu6 In our case, given the close temporal relationship to stent implantation, a tunnel injury causing a new baffle leak was suspected.
Follow-up echocardiography raised suspicion of a potential leak; however, due to modality limitations, CT was performed. Despite a detailed discussion of anatomy and study objectives with the radiology team, a definitive diagnosis was precluded by artefacts.
Ultimately, a repeat cardiac catheterisation confirmed a significant baffle leak, a recognised iatrogenic complication of stent implantation. Reference Mets, Bergersen, Mayer, Marshall and McElhinney7 This defect created a substantial shunt leading to decreased oxygen saturation. In our patient, the primary manifestation was desaturation without other severe complications. The placement of a covered stent effectively sealed the leak, resulting in marked clinical improvement.
Despite the challenges of diagnosing and managing baffle leaks in Fontan patients, this case highlights the importance of thorough post-procedural monitoring and multidisciplinary collaboration. The successful resolution of the leak led to significant clinical improvement, emphasising the need for vigilance in post-stenting follow-up.
Conclusion
In our case report, we aimed to underscore the potential for a significant baffle leak to occur after stent implantation, even in the setting of initially normal angiographic and clinical findings. Close monitoring of the patient in the days following the procedure is paramount. If atypical symptoms arise, cross-sectional imaging is crucial for establishing a diagnosis. Despite the complicated clinical course, the patient now reports a marked improvement in exercise tolerance and overall quality of life.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S1047951125101108.
Financial support
None.
Competing interests
None declared.
Ethical standard
The research does not involve human experimentation.
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