The Norwood Procedure is the first in a series of palliative surgical procedures to treat Hypoplastic Left Heart Syndrome (HLHS), one of the most complex congenital heart defects. HLHS typically involves a number of cardiac malformations that result in a non-functional left ventricle. The first surgical procedure to treat HLHS is the Norwood procedure, which has one of the highest mortality rates in pediatric cardiac surgery. This is largely due to the difficulty in providing sufficient pulmonary blood flow after reconstructing the hypoplastic aorta with the pulmonary artery. The two current options are the RV-PA (right ventricle to pulmonary artery) conduit and the B-T (Blalock-Taussig) shunt. The RV-PA conduit requires a ventriculotomy and results in complete regurgitation back in to the only functioning ventricle. However the use of an RV-PA conduit avoids the low systemic diastolic pressure associated with the B-T shunt, which is caused by its leaching of systemic blood throughout the entire cardiac cycle. Early outcomes are often improved with the RV-PA conduit, however long term detrimental effects to the right ventricle result in similar mortality and morbidity rates overall. A valved RV-PA conduit would allow for higher systemic diastolic pressure without regurgitation, decreasing the load on the right heart and avoiding the hypertrophy and tricuspid valve dysfunction that can lead to the need for transplant or even death.
A simple concept for providing better outcomes for the Norwood Procedure is to utilize a valved RV-PA conduit. This approach would limit regurgitation into the remaining functional ventricle, thus avoiding right heart hypertrophy. Previous attempts to create a functional valve in an RV-PA conduit in an ad-hoc fashion have been unsuccessful due to the small size of the conduit (4-8 mm) and the complex flow profile through them. The conduit is curved after implantation, and this causes complications for leaflets in a valved RV-PA conduits that have been surgically created. Additionally the high cost of development, regulatory barriers and the small size of the market associated with this congenital defect have been obvious barriers to development.
PECA Labs recently received Humanitarian Use Device (HUD) designation for their original product, the MASA valve, which is now being manufactured in a facility managed by a top medical device manufacturer. The MASA valve, a larger valved RV-PA conduit used in another rare surgical procedure, has shown greatly improved clinical results, compared to current options after more than 3 years and 49 patients with intra-operative construction. The material used for both products has been FDA approved for blood-contacting use. This should simplify the regulatory approval process, and the experience PECA labs has had with their previous product development should expedite the process of commercializing the valved conduit for the Norwood procedure.
APDC provided funding to validate the design of the pediatric valved conduit with a coupled solid mechanics and computational fluid dynamics (CFD) simulation and physical mock heart-loop testing; obtain HUD status for the device; and to develop the animal studies protocol for future use.