Long-term morphological changes in a cryopreserved pulmonary valve homograft

Lyophilized allografts without pre-treatment with glutaraldehyde are more suitable than cryopreserved allografts for pulmonary artery reconstruction

Various methods are available for preservation of vascular grafts for pulmonary artery (PA) replacement. Lyophilization and cryopreservation reduce antigenicity and prevent thrombosis and calcification in vascular grafts, so both methods can be used to obtain vascular bioprostheses. We evaluated the hemodynamic, gasometric, imaging, and macroscopic and microscopic findings produced by PA reconstruction with lyophilized (LyoPA) grafts and cryopreserved (CryoPA) grafts in dogs. Eighteen healthy crossbred adult dogs of both sexes weighing between 18 and 20 kg were used and divided into three groups of six: group I, PA section and reanastomosis; group II, PA resection and reconstruction with LyoPA allograft; group III, PA resection and reconstruction with CryoPA allograft. Dogs were evaluated 4 weeks after surgery, and the status of the graft and vascular anastomosis were examined macroscopically and microscopically. No clinical, radiologic, or blood-gas abnormalities were observed during the study. The mean pulmonary artery pressure (MPAP) in group III increased significantly at the end of the study compared with baseline (P=0.02) and final [P=0.007, two-way repeat-measures analysis of variance (RM ANOVA)] values. Pulmonary vascular resistance of groups II and III increased immediately after reperfusion and also at the end of the study compared to baseline. The increase shown by group III vs group I was significant only if compared with after surgery and study end (P=0.016 and P=0.005, respectively, two-way RM ANOVA). Microscopically, permeability was reduced by ≤75% in group III. In conclusion, substitution of PAs with LyoPA grafts is technically feasible and clinically promising.

Pulmonary Homografts for Aortic Valve Replacement: Long-term Comparison with Aortic Grafts

<p><b>Objective:</b> The use of homografts for aortic valve replacement (AVR) is an alternative to mechanical or biological valve prostheses, especially in younger patients. This retrospective comparative study evaluated our single-center long-term results, with a focus on the different origins of the homografts.</p><p><b>Methods:</b> Since 1992, 366 adult patients have undergone AVR with homografts at our center. We compared 320 homografts of aortic origin and 46 homografts of pulmonary origin. The grafts were implanted via either a subcoronary technique or the root replacement technique. We performed a multivariate analysis to identify independent factors that influence survival. Freedom from reintervention and survival rates were calculated as cumulative events according to the Kaplan-Meier method, and differences were tested with the log-rank test.</p><p><b>Results:</b> Overall mortality within 1 year was 6.5% (21/320) in the aortic graft group and 17.4% (8/46) in the pulmonary graft group. In the pulmonary graft group, 4 patients died from valve-related complications, 1 patient died after additional heterotopic heart transplantation, and 1 patient who entered with a primary higher risk died from a prosthesis infection. Two patients died from non-valve-related causes. During the long-term follow-up, the 15-year survival rate was 79.9% for patients in the aortic graft group and 68.7% for patients in the pulmonary graft group (<i>P</i> = .049). The rate of freedom from reoperation was 77.7% in the aortic graft group and 57.4% in the pulmonary graft group (<i>P</i> < .001). The reasons for homograft explantation were graft infections (aortic graft group, 5.0%; pulmonary graft group, 6.5%) and degeneration (aortic graft group, 7.5%; pulmonary graft group, 32.6%).</p><p><b>Conclusion:</b> Our study demonstrated superior rates of survival and freedom from reintervention after AVR with aortic homografts. Implantation with a pulmonary graft was associated with a higher risk of redo surgery, owing to earlier degenerative alterations.</p>