Title

Transcatheter pulmonary thrombectomy in an adult with Fontan circulation

Introduction

The Fontan procedure remains an important operation to palliate congenital heart defects, including hypoplastic left ventricle.¹ The operation separates the pulmonary and systemic circulations to improve arterial oxygenation and reduce volume overload. To maintain venous circulation to the lungs, a Fontan conduit bypasses the right ventricle, providing passive flow from the inferior vena cava into the pulmonary arteries. Due to its non-pulsatile nature, Fontan physiology is associated with an increased risk of thrombosis.^1,2 Warfarin is commonly prescribed to reduce the risk of thromboembolism.³

Clinical Case

A 33-year-old patient with D-transposition of the great arteries, mitral atresia, hypoplastic left heart syndrome, and ventricular septal defect received a Glenn shunt with lateral Fontan procedures as a child. His post-operative course was complicated by a stroke at age 6 and he was subsequently treated with warfarin with intermittent compliance over the years. Six weeks prior to presentation, the patient presented to his Cardiologist with progressive dyspnea, hypoxemia, and intermittent chest pain. On examination, he was tachycardic at 106 bpm, normotensive, tachypneic and hypoxic.

Lower extremity venous duplex showed no evidence of DVT. He was referred for right heart catheterization and pulmonary angiography. Selective pulmonary angiography revealed a large filling defect of the left pulmonary artery, with thrombus extending into the apical and basilar segments. The mean PA pressure was 26 mmHg. The patient was not felt to be a suitable candidate for systemic thrombolysis due to a remote history of stroke. Given the chronic and progressive nature of the symptoms, the thrombus was suspected to be largely subacute or chronic.

Mechanical thrombectomy was performed using the Inari FlowTriever® system. A 24F Flowtriever catheter was advanced into the left pulmonary artery and retrieved a large thrombus burden. Serial aspirations of the left pulmonary artery and its tributaries, with the assistance of the T2 Triever ® disc was successful in removing a significant amount of thrombus. A 20 French curved Triever ® catheter was advanced into the left basilar artery and aspirated removing a large amount of thrombus. Post-intervention, the mean PA pressure was 16 mmHg. The patient’s symptoms and saturations improved, and he was transitioned to apixaban to promote compliance.

Discussion

Adults with Fontan shunts have an increased risk of pulmonary thromboembolism. Transcatheter thrombectomy can be used in patients with significant hypoxia and/or hemodynamic effects with a contraindication to thrombolysis. Although warfarin is currently recommended, there is growing evidence to support the use of DOACs in patients with Fontan circulation. ^4–6