A Prospective Study of Patients With Hypoplastic Left Heart Syndrome (HLHS) Following Stage II Surgical Palliation

Hypoplastic left heart syndrome (HLHS) is a severe form of congenital heart disease that
consists of multiple obstructions to flow through the left heart and aorta, as well as
hypoplasia of the left ventricle. Most patients require a three-stage surgical protocol
starting within days of birth. Stage I of this process is the Norwood reconstruction (within
the first few days of life), Stage II (usually required within 3-8 months) involves creation
of a direct connection between the patient's superior vena cava and the pulmonary arterial
confluence (bidirectional Glenn anastomosis), and the last stage is creation of a Fontan
circulation (typically within the first 2-4 years). This "single ventricle" approach requires
the right ventricle to perform as the only circulatory pump for the entire body.

Our long-term goal is to develop regenerative strategies to strengthen and augment the right
ventricular muscle of the single-ventricle heart following surgical palliation in HLHS
patients. To determine the safety and feasibility of a cell-based therapeutic intervention at
the Stage II surgery, we aim to document the natural history of post-surgical care in HLHS
patients having undergone standard of care with protocol specific follow-up over the course
of a 6-month period.

This prospective study will document the natural history in patients with HLHS after planned
Stage II surgical palliation with a focus on cardiovascular parameters within 6 months
following surgery in 10 patients.