Ischemia-Reperfusion Injury in Porcine Aortic Valvular Endothelial and Interstitial Cells.

Ischemia-reperfusion injury (IRI) in the myocardium has been thoroughly researched, especially in acute coronary syndrome and heart transplantation. However, our understanding of IRI implications on cardiac valves is still developing. This knowledge gap becomes even more pronounced given the advent of partial heart transplantation, a procedure designed to implant isolated human heart valves in young patients. This study aims to investigate the effects of IRI on aortic valvular endothelial cells (VECs), valvular interstitial cells (VICs), and whole leaflet cultures (no separation of VECs and VICs). We employed two conditions: hypoxic cold storage reperfusion (HCSR) and normothermia (NT). Key markers, secreted protein acidic and cysteine rich (SPARC) (osteonectin), and inducible nitric oxide synthase (iNOS2) were evaluated. In the isolated cells under HCSR, VICs manifested a significant 15-fold elevation in SPARC expression compared to NT (p = 0.0016). Conversely, whole leaflet cultures exhibited a 1-fold increment in SPARC expression in NT over HCSR (p = 0.0011). iNOS2 expression in VECs presented a marginal rise in HCSR, whereas, in whole leaflet settings, there was a 1-fold ascent in NT compared to HCSR (p = 0.0003). Minor escalations in the adhesion molecules intercellular adhesion molecule (ICAM), vascular cell adhesion molecule (VCAM), E-selection, and P-selection were detected in HCSR for whole leaflet cultures, albeit without statistical significance. Additionally, under HCSR, VICs released a markedly higher quantity of IL-6 and IL-8, with respective p-values of 0.0033 and <0.0001. Interestingly, the IL-6 levels in VECs remained consistent across both HCSR and NT conditions. These insights lay the groundwork for understanding graft IRI following partial heart transplantation and hint at the interdependent dynamic of VECs and VICs in valvular tissue.

Outcomes in Primary Repair of Truncus Arteriosus with Significant Truncal Valve Insufficiency: A Systematic Review and Meta-analysis.

Data regarding the effect of significant TVI on outcomes after truncus arteriosus (TA) repair are limited. The aim of this meta-analysis was to summarize outcomes among patients aged ≤ 24 months undergoing TA repair with at least moderate TVI. A systematic literature search was conducted in PubMed, Scopus, and CINAHL Complete from database inception through June 1, 2022. Studies reporting outcomes of TA repair in patients with moderate or greater TVI were included. Studies reporting outcomes only for patients aged > 24 months were excluded. The primary outcome was overall mortality, and secondary outcomes included early mortality and truncal valve reoperation. Random-effects models were used to estimate pooled effects. Assessment for bias was performed using funnel plots and Egger's tests. Twenty-two single-center observational studies were included for analysis, representing 1,172 patients. Of these, 232 (19.8%) had moderate or greater TVI. Meta-analysis demonstrated a pooled overall mortality of 28.0% after TA repair among patients with significant TVI with a relative risk of 1.70 (95% CI [1.27-2.28], p < 0.001) compared to patients without TVI. Significant TVI was also significantly associated with an increased risk for early mortality (RR 2.04; 95% CI [1.36-3.06], p < 0.001) and truncal valve reoperation (RR 3.90; 95% CI [1.40-10.90], p = 0.010). Moderate or greater TVI before TA repair is associated with an increased risk for mortality and truncal valve reoperation. Management of TVI in patients remains a challenging clinical problem. Further investigation is needed to assess the risk of concomitant truncal valve surgery with TA repair in this population.

Immunogenicity of Homologous Heart Valves: Mechanisms and Future Considerations.

Pediatric valvar heart disease continues to be a topic of interest due to the common and severe clinical manifestations. Problems with heart valve replacement, including lack of adaptive valve growth and accelerated structural valve degeneration, mandate morbid reoperations to serially replace valve implants. Homologous or homograft heart valves are a compelling option for valve replacement in the pediatric population but are susceptible to structural valve degeneration. The immunogenicity of homologous heart valves is not fully understood, and mechanisms explaining how implanted heart valves are attacked are unclear. It has been demonstrated that preservation methods determine homograft cell viability and there may be a direct correlation between increased cellular viability and a higher immune response. This consists of an early increase in human leukocyte antigen (HLA)-class I and II antibodies over days to months posthomograft implantation, followed by the sustained increase in HLA-class II antibodies for years after implantation. Cytotoxic T lymphocytes and T-helper lymphocytes specific to both HLA classes can infiltrate tissue almost immediately after implantation. Furthermore, increased HLA-class II mismatches result in an increased cell-mediated response and an accelerated rate of structural valve degeneration especially in younger patients. Further long-term clinical studies should be completed investigating the immunological mechanisms of heart valve rejection and their relation to structural valve degeneration as well as testing of immunosuppressant therapies to determine the needed immunosuppression for homologous heart valve implantation.