Native Aortic Root Thrombosis After Norwood Palliation for Hypoplastic Left Heart Syndrome

Abstract

Background: Norwood palliation for hypoplastic left heart syndrome typically results in retrograde perfusion of the native aortic root. This may predispose to native aortic root thrombosis (NART).

Methods: Patients who underwent stage 1 Norwood palliation at Children's Hospital Colorado between 2003 and 2019 were retrospectively reviewed for NART. Additional patients were identified by a systematic literature review. Patient factors, operative details, presentation, diagnostic methods, treatments, and outcomes were analyzed.

Results: Three patients with NART were identified among 241 patients who had undergone stage 1 Norwood palliation at Children's Hospital Colorado (mean follow-up, 48 months). A fourth patient identified at Children's Hospital Colorado had undergone stage 1 palliation elsewhere. The systematic literature review identified 12 additional patients. Among the 16 patients, patients presented with new arrhythmias (38% [n = 6]), evidence of ischemia (31% [n = 5]), incidentally (19% [n = 3]), inability to wean from postoperative support (6% [n = 1]), and cardiac arrest (6% [n = 1). The diagnosis was made by transthoracic echocardiography (TTE) in 50% (n = 8), transesophageal echocardiography in 19% (n = 3), cardiac catheterization in 25% (n = 4), and cardiac computed tomography in 6% (n = 1). Importantly, 44% (n = 7) of patients were missed by TTE and subsequently diagnosed by other methods. Treatment strategies were surgical thrombectomy in 38% (n = 6), anticoagulation alone in 38% (n = 6), direct catheter thrombolysis in 19% (n = 3), and systemic thrombolysis in 6% (n = 1). The rate of mortality or transplant listing was 44% (n = 7).

Conclusions: NART is an underappreciated complication of Norwood palliation with high mortality. There should be a high index of suspicion for NART in patients after Norwood palliation with an unexplained complicated clinical course. Importantly, NART is frequently missed by TTE.