Anesthetic Management for EC-IC Bypass Procedure in a Patient with Fontan Physiology: Navigating a Vascular Multimorbidity

Abstract

The Fontan procedure is a palliative procedure that reduces mortality associated with complex congenital cardiac anomalies. With advanced surgical techniques and improved perioperative care, an increase in the survival rate of palliated complex heart disease patients is rightfully expected. These patients may be encountered in noncardiac surgical suites and require special considerations. We present an interesting case of a 34-year-old male with a rare combination of vascular anomalies in the form of Fontan physiology and moyamoya disease with secondary polycythemia, posted for extracranial-intracranial bypass. We describe the perioperative management of this patient, maintaining stable hemodynamic on dual fronts, avoiding compromise in pulmonary circulation under positive pressure ventilation (a consideration in Fontan physiology), as well as cerebral ischemic complications (known risk with moyamoya disease). Only one case has been reported so far with a similar combination of vascular multimorbidity, in a patient, who underwent pial synangiosis.

 

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Keywords

moyamoya disease - Fontan physiology - combined vascular morbidities

Introduction

Hypoplastic left heart syndrome (HLHS) is a complex congenital heart disease with a 95% mortality, accounting for 23% of neonatal deaths.[1] Fontan procedure, a palliative surgical procedure done in congenital univentricular heart diseases, had a prevalence of 66 people per million (ppm) in 2020.[2] Moyamoya disease is a unique cerebrovascular pathology involving progressive stenosis of major intracranial vessels with basal collateral angiogenesis, thus leading to a state of compensated yet compromised cerebral blood flow.[3] Unusual vascular conditions rarely coexist in physiological harmony, and require dual fronted hemodynamic management. Our patient had such coexisting vascular condition with moyamoya disease and Fontan physiology, posted for left extracranial-intracranial (EC-IC) bypass procedure.

 

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Case Report

A 34-year-old male presented with symptoms suggestive of transient ischemic attacks. Radiological workup, including magnetic resonance imaging of the brain with perfusion scan, led to a diagnosis of moyamoya disease. His magnetic resonance angiography ([Fig. 1]) showed severe stenosis of the bilateral internal carotid artery (left > right), with basal collateral development. He had a history of congenital HLHS palliated to Fontan circulation at the age of 20. Preoperative echocardiography revealed good laminar flow in the bidirectional Glenn graft to the right pulmonary artery, with good ventricular contractility, and no valvular regurgitation. He also had polycythemia, presumably secondary to moyamoya disease, with a hematocrit of 51. He was on aspirin 75 mg, continued perioperatively.

Fig. 1 Magnetic resonance (MR) angiogram showing severe irregular stenosis of the left intracranial carotid artery, with nonvisualization of bilateral middle cerebral arteries and multiple collateral vessels (moyamoya vessels).

After a multispecialty cross-collaboration, a left EC-IC bypass procedure was planned, under general anesthesia with invasive hemodynamic monitoring. Preoperatively, the patient had normal clinical respiratory parameters with oxygen saturation of 100%. Intraoperatively, standard monitors as per the ASA (American Society of Anesthesiology) guidelines were supplemented with invasive blood pressure (IBP), central venous pressure (CVP), nasopharyngeal temperature, urine output, and train-of-four monitoring. Transcutaneous defibrillator pads were applied before induction in anticipation of intraoperative arrhythmias. An initial heart rate of 40 beats per minute increased to 48 after intravenous atropine 0.6 mg. Arterial line was inserted preinduction under local anesthetic infiltration, to acquire real-time IBP monitoring. Anesthesia was induced with midazolam, fentanyl, etomidate, and vecuronium, and maintained with sevoflurane. A postinduction arterial blood gas analysis revealed a PaO2 (partial pressure of oxygen) of 250 mm Hg and PaCO2 (partial pressure of carbon dioxide) of 34 mm Hg, which were maintained in that range. We maintained IBP in the baseline range, core body temperature between 35 and 36°C, and CVP 10 to 15 mm Hg ([Fig. 2]). Following induction, one episode of tachycardia was managed with 60 mg of intravenous lignocaine. Brief occasions of hypotension despite maintaining targeted CVP and pulse pressure variation were managed with aliquots of phenylephrine to avoid overhydration. Lung protective ventilation strategy was used to keep pulmonary pressures in check and maintain normocapnia. Postoperatively, the patient was extubated on table and had 24-hour intensive care unit stay for continued invasive hemodynamic and clinical neurological monitoring. He had an uneventful perioperative course, with a good immediate neurological outcome.

Fig. 2 Intraoperative vital parameters maintained in accordance with the combined implications of the two conditions.

 

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Discussion

Fontan procedure is a palliative surgery for complex univentricular heart conditions, restructuring cardiovascular anatomy to ensure good systemic blood flow and adequate oxygenation. A direct or interposed total caval pulmonary connection establishes good pulmonary blood flow, oxygenates circulating blood, and unloads the systemic ventricle.[4] Plappert et al reported a prevalence of 66 ppm in 2020 for Fontan physiology, projecting an increase to 79 ppm by 2030.[2] They described a progressive age distribution that indicates increasing life expectancy and subsequently their anticipated presentation for noncardiac surgeries. This increase in apparent life expectancy has been attributed to advanced surgical amenities. However, this palliative procedure comes with its own set of complications. The absence of a subpulmonary pump makes circulation, oxygenation, and cardiac output highly dependent on the central venous volume. Adequate hydration to maintain caval pressure of 10 to 14 mm Hg, while avoiding overhydration and lymphatic stasis, is an aptly named concept, the “Fontan Paradox.”[4] Gewillig and Brown described the Fontan concept wherein the pulmonary vascular resistance acts as a dam wall, causing congested upstream and diminished downstream circulation leading to a vasculature progressively failing with advancing age.[5] Atrial arrhythmias have a measurable risk (15–60%), increasing with age.[6] A working knowledge of this unusual functional anatomy helped achieve the implicated intraoperative goals.

Moyamoya disease is a condition of compromised cerebrovascular flow due to progressive cerebral vasoconstriction and reliance on basal collaterals.[3] Moyamoya patients often come to the surgical suites for bypass procedures. The anesthetic management involves ever-evolving precise goals, including aggressive hydration to maintain normal to slightly higher intravascular volume, hypertension in the physiological range, normocapnia (instead of higher PaCO2 which can potentially cause cerebral steal in the maximally dilated cerebral vessels in the ischemic areas), normothermia, prevention of ischemia by ensuring adequate hematocrit and oxygenation (accounting for the increased oxygen extraction ratio in events of compromised perfusion), and blood pressure control to prevent cerebral hyperperfusion post-revascularization.[7]

Undoubtedly, achieving these precise goals at critical time points during the surgery was challenging in our patient with a complex cardiac physiology. We devised an anesthetic plan with quantitative targets, achieving cardiorespiratory goals with real-time hemodynamic monitoring, goal-directed fluid therapy, preparedness for anticipated complications, and tiding over transient hemodynamic inconsistencies with short-acting vasoactive drugs.

Subramaniam et al, in 2006, reported a similar case of Fontan physiology with moyamoya disease posted for pial synangiosis, with postoperative intracranial hemorrhage and subsequent management. They describe the use of pulmonary artery catheter intraoperatively only if compromised contractility requires invasive monitoring. We had similar goals as in this case, with additional recruitment of goal-directed fluid therapy.[8]

This combination of vascular anomalies, though not part of a spectrum, is most challenging. Precise control of pulmonary circulation to maintain good cerebral blood flow in the face of a compromised vasculature while avoiding cerebral edema was crucial for our anesthetic management.

 

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Conclusion

With improved life expectancy of palliated cardiac conditions, we are likely to encounter patients with coexisting complex comorbidities for intracranial procedures. Understanding the pathophysiology and anesthetic implications of each disease helped establish precise intraoperative goals. Finally, a multispecialty cross-collaboration along with advanced techniques like goal-directed therapy for intravenous fluid and vasoactive drugs led to a good outcome in our patient.

 

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Conflict of Interest

None declared.

• References

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• 3 Bang OY, Fujimura M, Kim SK. The pathophysiology of moyamoya disease: an update. J Stroke 2016; 18 (01) 12-20
• 4 Mazza GA, Gribaudo E, Agnoletti G. The pathophysiology and complications of Fontan circulation. Acta Biomed 2021; 92 (05) e2021260
• 5 Gewillig M, Brown SC. The Fontan circulation after 45 years: update in physiology. Heart 2016; 102 (14) 1081-1086
• 6 Laubham M, Blais B, Kamp AN. Atrial arrhythmias in adults with Fontan palliation. Cardiol Ther 2023; 12 (03) 473-487
• 7 Yang KJ, Mistry P, Ayrian E. Update on the anesthesia management in adult patients with moyamoya disease. Curr Opin Anaesthesiol 2024; 37 (05) 439-445
• 8 Subramaniam B, Soriano SG, Michael Scott R, Kussman BD. Anesthetic management of pial synangiosis and intracranial hemorrhage with a Fontan circulation. Paediatr Anaesth 2006; 16 (01) 72-76

Publikationsverlauf

Artikel online veröffentlicht:
15. September 2025