Purpose or Case Report: In this exhibit we will review the multimodality imaging findings in patients with HLHS using chest radiography (CXR), computed tomography (CT) and magnetic resonance imaging (MRI). We will discuss the physiologic basis for the radiologic findings of HLHS, describe the palliative surgical procedures to correct HLHS and their complications.
Methods & Materials: Background: Hypoplastic left heart syndrome (HLHS) consists of a spectrum of cardiac abnormalities characterized by hypoplasia of the left ventricle and ascending aorta. HLHS comprises 1.2 -1.5% of all congenital heart defects with an annual incidence of 0.16-0.36 per 1000 live births. Without surgical correction HLHS is uniformly fatal. Before the availability of surgical correction HLHS accounted for 25% of all neonatal cardiac deaths. Through revolutionary surgical work, a series of reconstructive palliation techniques have been developed allowing those infants to survive into childhood. The pediatric radiologist now sees a larger population of HLHS patients making it imperative to understand the imaging of these palliative techniques.
Results: Imaging Findings: In a neonate exhibiting early clinical signs of distress the chest radiograph is often the first imaging study ordered.
Cross sectional imaging such as CT and MRI are useful, not only for characterizing anatomy but for surgical planning and decision making. The surgical palliation of HLHS consists of 3 stages aimed at constructing separate, nonobstructed pulmonary and systemic vascular circulations with systemic flow returning passively to the lungs and a single ventricle providing systemic blood flow. The first stage, known at the Norwood Procedure consists of a creation of a “neo-aorta,” atrial septectomy, patent ductus arteriosus (PDA) ligation and the formation of a controlled source of pulmonary blood flow through a Blalock-Taussig shunt (BTS) or Sano modification. The second stage results in the creation of a bidirectional superior cavopulmonary connection using a bidirectional Glenn shunt and ligation of previously created BTS. The third stage is the Fontan operation which reroutes the systemic venous return from the inferior vena cava directly to the lungs through a conduit resulting in bypassing the single functional ventricle.
Conclusions: The pre- and post-surgical imaging features of hypoplastic left heart syndrome are complex and cross -sectional imaging can assist the radiologist in understanding surgical palliative repairs as well as identifying potential complications.