The Norwood staged repair for hypoplastic left heart syndrome (HLHS) has saved the lives of thousands of children. Stage I of this procedure involves augmenting the underdeveloped aorta, and at present this is done using either cryopreserved human allograft material (pulmonary artery or aorta) or glutaraldehyde pretreated bovine pericardium. The proposed research will investigate using bovine pericardium, pretreated with a novel cross-linker, triglycidylamine (TGA), synthesized by our group. TGA, when used to crosslink heterograft biomaterials, confers stability, biocompatibility, calcification resistance and mechanical properties that are superior to glutaraldehyde, the cross-linker used to prepare clinically used heterograft biomaterials. In addition we will use TGA in combination with ethanol pretreatment, which confers additional calcification resistance. TGA-ethanol pretreated bovine pericardium is hypothesized to be a better candidate material than glutaraldehyde fixed bovine pericardium for Stage I Norwood aortic augmentation because of a number of advantages of TGA cross-linking compared to glutaraldehyde including greater material stability, mechanical properties more comparable to native tissue and calcification resistance. The goal of these investigations is to carry out preclinical studies in a sheep model under GLPs for submission to the FDA for an IDE for a TGA-ethanol pretreated bovine pericardium implant. This will be the basis of our competitive Phase 2 submission following the conclusion of the proposed initial two year NHLBI C-TRIP program.
Specific Aim 1. Prepare and characterize TGA-ethanol pretreated bovine pericardium. This material will be compared with the currently manufactured glutaraldehyde pretreated bovine pericardium (control implants). Endpoints will include indices of crosslink stability, microscopic morphology and mechanical properties per unaxial testing.
Specific Aim 2. Carry out animal model studies of the Norwood I aortic root augmentation procedure using TGA-ethanol pretreated bovine pericardium versus glutaraldehyde pretreated bovine pericardium (controls) in juvenile sheep with survival to 150 days. Prior to euthanasia animals will undergo a cardiac catheterization and angiography procedure in order to obtain physiologic endpoints and imaging studies of the aortic augmentation site comparing two types of xenograft implants.
Specific Aim 3. Explantation at 150 days will be followed by analyses of aortic augmentation specimens for a number of endpoints including macroscopic and microscopic assessment of material integrity, calcification, thrombosis, and inflammation. Calcification analyses will be carried out on explants and samples will also be studied for changes in mechanical properties compared to unimplanted material parameters.
Congenital heart disease affects thousands of children in the United States, and accounts for billions of dollars in medical care costs. This proposal will investigate a new pediatric cardiac surgery device, a TGA-ethanol pretreated bovine pericardial xenograft, that may improve outcomes for the most severe form of congenital heart disease, the hypoplastic left heart syndrome.
| Connolly, Jeanne M; Bakay, Marina A; Alferiev, Ivan S et al. (2011) Triglycidyl amine crosslinking combined with ethanol inhibits bioprosthetic heart valve calcification. Ann Thorac Surg 92:858-65 |
