Aortic valve neocuspidization using the Ozaki technique has shown promising results both in adults and children.
A systematic search of the PubMed and Cochrane databases was performed up to November 13, 2021. Individual patient data were reconstructed and analyzed from the Kaplan-Meier curves of all eligible studies for time-to-event outcomes.
We included a total of 22 studies reporting on 1,891 patients that underwent Ozaki reconstruction. Mean age at the time of surgery was 43.2 ± 24.5 years (65 ± 12.3 years for adult patients and 12.3 ± 3.8 years for pediatric patients). The most common indication was aortic stenosis (46.4%, 95% CI 34.1-58.6). Mean cross-clamp and cardiopulmonary bypass duration were 106.8 ± 24.8 minutes and 135.2 ± 35.1 minutes, respectively. Permanent pacemaker was implanted in 0.7% (95% CI 0.4-1.2) of the patients. At discharge, mean effective orifice area was 2.1 ± 0.5 cm 2 /m 2 . At latest follow-up, peak gradient was 15.7 ± 7.4 mm Hg and only 0.25% (95% CI 0-2.3) had moderate aortic insufficiency. In-hospital mortality was 0.7% (95% CI 0.1-1.7). Late mortality was 1.9% during a mean follow-up of 38.1 ± 23.8 months. One-year, 3-year, and 5-year freedom from reoperation rates were 98.0 %, 97.0 % and 96.5%, respectively. More than half of the reoperations were due to infective endocarditis (51.5%, 95% CI 18.3-84.0). In our cohort, the risk of endocarditis per patient per year was 0.5%.
The midterm outcomes of the Ozaki procedure are excellent in terms of hemodynamics, survival, and freedom from reoperation. Acquiring long-term follow-up will help solidify this technique in the cardiac surgery armamentarium.
Central illustration: Long-term hemodynamics and results of time-to-event analyses.
The concept of the ideal cardiac valve prosthesis is predicated upon optimized hemodynamics, minimal postoperative morbidity, lasting durability, and ultimately prolonged patient survival with superior quality of life. Mechanical valves require lifelong anticoagulation and therefore predispose to hemorrhagic events. On the other hand, biological prostheses mount a chronic inflammatory response, are prone to structural degeneration, and typically require a reintervention within 10 to 15 years. Efforts to replace aortic valve (AV) tissue with biological material such as fascia lata and pericardium date back to the 1960s.
Ozaki et al developed their AV reconstruction technique at Toho University Ohashi Medical Center where they standardized the use of glutaraldehyde-treated autologous pericardium to perform trileaflet aortic valve neocuspidization (AVneo). In 2011, they published their initial experience of 404 patients that postoperatively exhibited favorable hemodynamics and low rates of AV insufficiency (AI). In 2018, the Ozaki group described their full cohort of 850 patients in whom observed survival (OS), freedom from reoperation, and the rate of moderate or greater AI were 85.9%, 95.8%, and 7.3%, respectively within a mean follow-up of 4.4 years.
Neocuspidization offers several benefits in terms of physiology. First, it preserves the natural expansion of the aortic root during systole. Second, in contrast to ring annuloplasty repairs, AVneo does not involve the use of a sewing ring. Therefore, it achieves maximum effective orifice area (EOA) and low transvalvular gradients. Lastly, long-term coumadin anticoagulation is not required. Although repair approaches are limited to regurgitant valves, the Ozaki procedure can be used to treat a wide spectrum of AV pathology including aortic stenosis, AI, infective endocarditis, and prosthetic valve endocarditis.
Most centers abide by the original Ozaki protocol and continue to utilize autologous pericardium for their neocuspidization efforts. Nevertheless, AVneo with xenologous pericardium has been described as well. The commonly used CardioCel bovine pericardium is subjected to an anti-calcification tissue engineering process (ADAPT TEP) which minimizes cytotoxicity by removing lipids, cellular remnants, nucleic acids and α-Gal epitopes followed by low concentration glutaraldehyde crosslinking. Subsequent detoxification strips the final product of all lingering glutaraldehyde. Ultimately, the CardioCel patch is sterilized and stored in a glutaraldehyde-free solution. On the other hand, photofix bovine pericardium is prepared by a dye-mediated photooxidation method that avoids the use of glutaraldehyde, is biocompatible, resistant to calcification and elicits minimal inflammatory responses. Encouraging results have also been reported in pediatric patients, making the Ozaki reconstruction a potentially viable alternative or bridging alternative to the Ross procedure. That said, much of our documented experience with AVneo stems from relatively small case series. In the present study, we sought to synthesize all available data on the hemodynamic benefits and durability of the Ozaki reconstruction through a meta-analysis of patient-level, time-to-event data.