Hypoplastic Left Heart Syndrome By Lee B Beerman, MD, Children's Hospital of Pittsburgh of the University of Pittsburgh School of Medicine Reviewed / Revised Apr 2023 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points More Information Topic Resources Hypoplastic left heart Norwood Procedure Overview of Hypoplastic Left.. Hypoplastic left heart syndrome consists of hypoplasia of the left ventricle and ascending aorta, maldevelopment and hypoplasia of the aortic and mitral valves (frequently aortic atresia is present), an atrial septal defect, and a patent ductus arteriosus.