Freehand cryopreserved mitral valve allograft with flexible ring in the pig

Cryopreserved valve allografts have proven satisfactory in aortic and pulmonary positions but not mitrally because of the difficulty in properly aligning the mitral valve allograft due to the complex subvalvular apparatus. To make the surgical procedure easier, we developed a freehand cryopreserved mitral valve allograft with a flexible ring.

Whole cryopreserved mitral valve allografts with the papillary muscle, chordae, and leaflets from donor pigs were implanted mitrally in recipient pigs under cardiopulmonary bypass divided into 2 experimental groups; control allografts without the ring (n = 6) (CA group) and allografts with a flexible ring (n = 7) (RA group). Postimplantation hemodynamics and valvular function were evaluated by measuring arterial pressure, left ventricular end diastolic pressure, and left atrial pressure and by evaluating 2-dimensional echocardiography. Allografts were evaluated pathohistologically after cryopreservation and surgery by light microscopy.

Hemodynamics did not differ significantly between groups. Aortic cross-clamping and Cardiopulmonary bypass times were significantly shorter in the RA group than the CA group (p < 0.05). Pigs requiring optional procedures with sutured annuloplasty and valvuloplasty numbered more in the CA group than the RA group. Postoperative echocardiography showed satisfactory mitral valve opening in diastole and good leaflet coaptation in systole in both groups. Light microscopic examination of cryopreserved allografts after surgery showed almost normal structures.

Acute hemodynamic function and morphology of freehand cryopreserved valve allografts implanted mitrally in pigs proved acceptable. Adaptation of the flexible ring to allografts might be useful for technical benefit to facilitate accurate positioning of mitral subvalvular apparatus at implantation.