Pulmonary valve replacement using a bioprosthesis is among the most common strategies to address right ventricular outflow tract (RVOT) problems in adults with congenital heart disease, particularly in patients with repaired Fallot’s tetralogy during childhood. However, the use of these bioprostheses in the RVOT is an off-label indication. Currently, there remains debate about the most suitable bioprosthesis for this context, as the surgical community continues the relentless search for a valve with enhanced durability to minimize the frequency of complex reinterventions.
Today’s article aims to evaluate the outcomes of the new Inspiris Resilia (Edwards Lifescience Inc) compared with the Mosaic (Medtronic Inc), the bioprosthesis previously used at Sandford University Hospital (California). The study reviewed all pulmonary valve replacements with either Mosaic or Inspiris bioprostheses, ranging from 19 mm to 29 mm in size. Freedom from moderate or greater prosthetic regurgitation, stenosis with a Doppler gradient >36 mm Hg, or reintervention were analyzed.
A total of 225 patients were included, 163 with the Mosaic valve and 62 with the Inspiris valve. No significant differences in baseline characteristics were found between cohorts. Postoperative transprosthetic gradients were low in both groups, albeit slightly higher in Mosaic recipients. No patient was discharged with moderate or severe prosthetic regurgitation. Median follow-up was 7 years for Mosaic recipients and 1.7 years for Inspiris recipients. At three years, moderate or greater regurgitation occurred in 10 Mosaic patients and 9 Inspiris patients. Freedom from moderate or severe regurgitation was 93% in the Mosaic cohort and 69% in the Inspiris cohort. Rates of stenosis with a maximum gradient of 36 mm Hg were similar between cohorts. Regarding reinterventions, two Inspiris prostheses were reintervened within 14 months due to thrombosis: one for endocarditis and another following a percutaneous valve implantation. In the Mosaic cohort, only one patient underwent reintervention within the first two years, electively replacing the valve during pulmonary branch expansion. In multivariate analysis, Inspiris valve implantation and prosthesis size were risk factors for prosthetic regurgitation.
The authors concluded that the Inspiris valve shows a higher rate of moderate or severe regurgitation compared to Mosaic valves. This finding suggests that the durability of this new prosthesis in the pulmonary position may not surpass that of other commonly used bioprostheses.
COMMENTARY:
The Inspiris Resilia bioprosthesis, developed in 2004 and marketed in 2017, is constructed from bovine pericardium incorporating innovative leaflet preservation technology. Its processing achieves a stable reduction of free aldehydes, preventing the calcification-glycerolization cycle that exposes more aldehydes, thereby accelerating calcification. The positive outcomes of Resilia technology were demonstrated in the 2017 COMMENCE Aortic Trial, which reported low transprosthetic gradients, minimal regurgitation, and no structural valve deterioration at 5 years. Additionally, this valve is designed for future percutaneous valve-in-valve procedures via radiopaque markers and an expandable zone (Vfit technology). These features, along with dry storage and excellent clinical outcomes, position it as a worthy successor to the Perimount Magna Ease.
Essentially, the Inspiris Resilia is a prosthesis designed and validated for the left heart, specifically the aortic position, where it performs exceptionally. However, the hemodynamics and requirements of a bioprosthesis in the right heart differ significantly. Just as one type of nut does not fit all bolts, not all bioprostheses suit every position. Such oversimplifications disregard the intricacies of cardiac physiology and hemodynamics. Early experiences with the Inspiris Resilia bioprosthesis (discussed in a previous blog entry) suggest failures may result from several mechanisms. On the one hand, bovine leaflets may require higher pressure to move freely, and pulmonary pressures may be insufficient to achieve optimal leaflet excursion, potentially leading to the recorded regurgitations. Porcine leaflets, being thinner, might function better in lower-pressure circulations. However, bovine leaflets in Perimount Magna Ease bioprostheses have not shown similar behavior in the pulmonary position. Another hypothesis involves Vfit technology, which may allow prosthetic ring expansion in a distensible RVOT. It’s important to note that while the aortic root is anchored within the fibrous cardiac skeleton, the pulmonary valve rests on a muscular infundibulum and lacks fibrous support. This lack of rigidity and systolic expansion might hinder adequate leaflet coaptation when supported on a malleable frame.
Despite being a single-center, retrospective study with a limited sample size, this research successfully demonstrated a statistically significant higher incidence of prosthetic regurgitation in Inspiris Resilia recipients in the pulmonary position.
In conclusion, the hypotheses surrounding Inspiris Resilia’s failure in the pulmonary position are numerous and likely multifactorial. What is clear is that its performance in the pulmonary position differs significantly from its success in the aortic position. In war and love, anything goes, but the Inspiris valve in the pulmonary position appears not to.
REFERENCE:
Ragheb DK, Martin E, Jaggi A, Lui GK, Maskatia SA, Ma M, et al. Short- and Mid-Term Results of Pulmonary Valve Replacement with the Inspiris Valve. Ann Thorac Surg. 2024 Jun;117(6):1203-1210. doi: 10.1016/j.athoracsur.2023.07.049.
