Left ventricle after palliation of hypoplastic left heart syndrome: friend, fiend, or innocent bystander?

Hypoplasia of the left side of the heart is the most common cause of death from congenital heart disease in the first weeks of life. Once considered a surgically fatal disease, hypoplasia has been successfully palliated for more than 30 years. Although the palliative route is staged by an early differential bypass of the systemic outflow and the venous inflow to the right ventricle, the left ventricle remains anatomically and biologically influential throughout. Given the variation of the left ventricle, contemporary outcomes for different hypoplastic left heart subsets can vary both early after palliation and long term. This review critically examines the contemporary understanding of the structure and function of the hypoplastic ventricle in this syndrome. It also provides insight into future research directions relevant to clinicians and surgeons.