Evaluation of the decellularized pulmonary valve homograft (SynerGraft)

Rejection is thought to contribute to the degeneration of valved homografts. A novel cryopreserved decellularized homograft valve (SynerGraft; CryoLife, Inc.) offers the unique opportunity to gain new insight into the immunology of homograft implantation and its significance for valve function.

Twenty-four patients (group I; mean age 37 +/- 11 years) underwent implantation of a pulmonary SynerGraft and were examined at one and six months postoperatively; 22 patients (group II; mean age 41 +/- 17 years) with conventional homografts served as controls. Temperature, C-reactive protein (CRP) levels and white blood cell count (WBC) were studied perioperatively. Follow up included echocardiography and anti-human leukocyte antigen (HLA) class I antibody determination.

Significantly lower temperatures were measured in group I (p = 0.019). CRP level and WBC each increased postoperatively, but did not differ between groups. During follow up, none of the SynerGraft patients became positive for anti-HLA antibodies, compared with 66% of controls (p = 0.011). Homograft diameter and valve orifice area were decreased significantly at one month after surgery in groups I and II (25 +/- 1 versus 18 +/- 3 mm; 25 +/- 1 versus 19 +/- 2 mm, respectively; p <0.001 both groups). Transvalvular pressure gradients significantly increased during follow up.

Implantation of the SynerGraft pulmonary homograft appeared safe, and though evidence was found of a reduced immunologic response after SynerGraft implantation this (unexpectedly) did not translate into any hemodynamic advantage. Hence, factors other than rejection appear as the main contributions to the observed functional changes.