Do Fresh Decellularized Pulmonary Artery Homografts Show Adaptive Growth? Considerations Twelve Years after Implantation of Various RVOT Conduits

Background: Conduit outgrowth or shrinking often limit conduit durability. Decellularized fresh homografts are one attempt to mitigate this undesired development. Based on the results of 3533 regularly conducted follow-up examinations of 617 patients of our multicenter RVOT registry who obtained bovine jugular veins (BJV), cryopreserved (CPH) or fresh decellularized (DPH) pulmonary homografts and had initial and follow-up measurements of weight and pulmonary valve diameter, we looked for the device with optimal size development after implantation.

Methods: 216 patients had received a CPH; 310 BJV; 91 DPH. Median age at implantation was 6.9 years (2 days-41 years); 37.6 years (0.3–62.5); 13.5 (0.5–50.9), and total follow-up was 2120; 1892; 464 years, respectively. Growth of too small conduits and shrinking of too large conduits was considered appropriate. Thus, for each examination the diameter change in respect to the diameter at implantation was paired with the z-value of the same examination. A negative z-value coupled with a diameter increase was considered positive, as well as diameter decrease in case of positive z-values. Other couples were considered a negative development. To take the population differences into account, we included the differing factors in a logistic regression: considering conduit type, age and z value at implantation and time after implantation as potential risk factors for undesired size development, we looked for factors contributing significantly (p < 0.05) to desired development. Apart from the size development we calculated freedom from explantation at 10 years of the 3 devices.

Results: Unadjusted 10 year freedom from explantation was 76.9 ± 3.0% (BJV), 87.3 ± 2.7% (CPH) and 100% (DPH) (p = 0.02). 18.4% of the BJV examinations showed desired development; 16.0% of CPH and 47.7% of DPH (p < 0.001). In the regression model, significant factors (p < 0.001) for a positive size development were DPH (OR 3.4 referenced to BJV) and greater z value at implantation: 1.06; the other factors decreased this probability (CPH: OR = -0.70, implantation age [1 year]:0.98, time after implantation [year]: 0.93).

Conclusion: Positive pulmonary valve diameter development in the sense of adapted growth is observed significantly more often in fresh decellularized pulmonary homografts than in bovine jugular veins or cryopreserved homografts.