Search

The purpose of this study was evaluation of an ice-free cryopreservation method for heart valves in an allogeneic juvenile pulmonary sheep implant model and comparison with traditionally frozen cryopreserved valves. Hearts of 15 crossbred Whiteface sheep were procured in Minnesota. The valves were processed in South Carolina and the pulmonary valves implanted orthotopically in 12 black faced Heidschnucke sheep in Germany. The ice-free cryopreserved valves were cryopreserved in 12.6\~mol/l cryoprotectant (4.65, 4.65, and 3.31\~mol/l of dimethylsulfoxide, formamide and 1,2-propanediol) and stored at -80°C. Frozen valves were cryopreserved by controlled slow rate freezing in 1.4\~mol/l dimethylsulfoxide and stored in vapor-phase nitrogen. Aortic valve tissues were used to evaluate the impact of preservation without implantation. Multiphoton microscopy revealed reduced but not significantly damaged extracellular matrix before implantation in frozen valves compared with ice-fre e tissues. Viability assessment revealed significantly less metabolic activity in the ice-free valve leaflets and artery samples compared with frozen tissues (P\~

Transplantation of cryopreserved heart valves (allografts) is limited by immune responses, inflammation, subsequent structural deterioration and an expensive infrastructure. In previous studies we demonstrated that conventional frozen cryopreservation (FC) is accompanied by serious alterations of extracellular matrix (ECM) structures. As the main culprit of the observed damages ice crystal formation was identified. Objective of this study was the application principles of cryoprotection as observed in nature, occurring in animals or plants, for ice-free cryopreservation (IFC) of heart valves. Using IFC, valves were processed and stored above the glass transition temperature of the cryoprotectant formulation (-124 degrees C) at -80 degrees C to avoid any ice formation, tissue-glass cracking and preserving ECM. After implantation in the orthotopic pulmonary position in sheep, we demonstrate that IFC resulted in cell free matrices, while maintaining crucial ECM-components such as elastin and collagen, translating into superior hemodynamics. In contrast, we reveal that FC valves showed ECM damage that was not restored in vivo, and T-cell inflammation of the stroma with significant leaflet thickening. Compared to currently applied FC practice IFC also reduced infrastructural needs for preservation, storage and shipping. These results have important implications for clinical valve transplantation including the promise of better long-term function and lower costs.

We report findings in spiral-CT from 11 adolescent or adult patients after atrial switch operation. The results demonstrate that computed tomography, particularly with the use of three-dimensional surface reconstruction, is very useful as a highly sensitive procedure for the detailed depiction of residua and sequelae after inflow correction for complete transposition. Especially systemic venous obstruction (SVO) is a well know complication following Mustard procedure for transposition of the great arteries. Demonstration of such obstruction is important, since the recognition and quantification of caval obstruction by clinical techniques is unreliable and indeed often impossible. Imaging procedures such as spiral computed tomography are important for this purpose. Advantages of spiral computed tomography, particularly with three-dimensional reconstruction, are discussed. The images were compared with findings in echocardiography and/or angiography affecting the site of operation.