Ongoing trials
There are several ongoing studies testing the feasibility and efficacy of stem cell therapies for single ventricle diseases such as HLHS. These trials focus on what are the most effective stem cells, what is the best timing in the 3-stage repair, and what is the optimal delivery method. Phase IIb trial testing the efficacy of intramyocardial injections umbilical cord blood cells during Stage II (Glenn) repair. Phase I trial testing the efficacy of autologous cord blood cell infusion during Stage 1 (Norwood) repair within two-to-three days of birth. The ELPIS trial is a phase I/IIb open pilot testing the efficacy and safety of intramyocardial donor human mesenchymal stem cell injections in patients during Stage 2 (Glenn) and Stage 3 (Fontan) repairs. Phase I trial testing the efficacy of umbilical cord blood intramyocardial injections during Stage 2 (Glenn) repair. The PERSEUS study is a phase II trial testing the efficacy of intracoronary infusions of cardiac progenitor cells and evaluating function 3-months post-treatment. APOLLON study is a phase III clinical trial testing the efficacy and safety of intracoronary injections of autologous cardiac stem cells during Stage 2 (Glenn) or Stage 3 (Fontan) repair. CHILD Study is a phase I clinical trial testing the feasibility and safety of intramyocardial injections of c-kit+ cells during Stage 2 (Glenn) repair.It is important to keep in mind that patients with HLHS are at increased risk of developing heart failure as adults. It remains unknown if these potential therapies would reduce the future risk of heart failure in these patients.
A study in 2003 concluded that a selection of physicians who are experts in the care of children with HLHS were evenly split when asked what they would do if their own children were born with HLHS, with 1/3 stating that they would choose surgery, 1/3 stating that they would choose palliative (compassionate) treatment without surgery, and 1/3 stating that they are uncertain which choice they would make.The three-stage procedure is a palliative procedure (not a cure), as the childs circulation is made to work with only two of the hearts four chambers. Norwood procedure
The first step is the Norwood procedure. In this procedure, the right ventricle is used to pump blood into the systemic circulation. Since the right ventricle is no longer directly pumping blood to the lungs, a shunt is required in order to pass deoxygenated blood through the lungs. Either the subclavian artery can be connected to the pulmonary circulation (Blalock-Taussig shunt), or a shunt is made directly from the right ventricle to the pulmonary circulation (Sano shunt). The narrow aorta is enlarged using a patch to improve blood flow to the body.During this time the baby may be medically fragile and have feeding problems because the heart is working very hard. There is a considerable degree of venous mixing in the right ventricle, leading to lower oxygenation saturation. In addition, both the Blalock-Taussig and the Sano shunts expose the lungs to systemic arterial pressures, leading to long-term pulmonary hypertension and eventually heart failure.