Hypoplastic left heart syndrome
Hypoplastic left heart syndrome (HLHS) is associated with a systemic right ventricle and a remnant left ventricle. The disease represents a spectrum, with the left ventricular cavity appearing of various sizes but being insufficient to sustain a bi-ventricular physiology. The competency of the tricuspid valve is important to assess, as it will become the atrio-ventricular valve of the systemic ventricle. HLHS may also be associated with a globular shape of the right ventricle and various degree of fibro-endoelastosis (often appearing as brightness of the endocardium on echocardiography). One may classify based on the aortic and mitral valve anatomy/physiology. Categories include: mitral stenosis / aortic stenosis (MS/AS), mitral stenosis / aortic atresia (MS/AA), mitral atresia / aortic atresia (MA/AA) or mitral atresia / VSD / aortic stenosis. The entire pulmonary venous return is dependent on the size of the inter-atrial communication. As such, an intact or restrictive atrial septum is of particular concern and may be associated with fetal pulmonary vascular remodelling. As these patients are dependent on low pulmonary vascular resistance to complete the single ventricular palliation, a re-modeled pulmonary vascular bed is of great concern. More on HLHS here.