Aortic and Pulmonary Valve Fenestrations: An Acquired Anatomic Entity During Adult Life

This study aims to identify and characterize fenestrations in the aortic and pulmonary valves using an endoscopic approach and compare their prevalence and morphology in adult and fetal hearts. The research explores whether these fenestrations are congenital or acquired and their potential clinical implications. We analyzed 41 adult human hearts (mean age: 74.25 years; range: 62-92) and 97 fetal human hearts (mean gestational age: 26 weeks; range: 12-40). Specimens were preserved in alcohol-phenol-formaldehyde and examined using a Stryker 5 mm 0 degree endoscope to visualize valve structures in situ, followed by post-endoscopic dissection. Two independent investigators assessed the specimens for fenestration prevalence, distribution, and morphology, categorized into ovoid, filamentous, and fenestrated types. Fenestrations were absent in all fetal hearts. Fenestrations were identified in 75.61% of adult hearts (31/41), with 74 fenestrations observed in total. Of these, 41 were in the pulmonary valve and 33 in the aortic valve. Ovoid fenestrations predominated in both valves (aortic: 76.3%, pulmonary: 85%), with significant distribution along leaflet edges, particularly in the left coronary and semilunar leaflets. No correlation with age or sex was found. The findings from this study suggest that valve fenestrations are more likely to be acquired postnatally, rather than representing congenital anomalies. The complete absence of fenestrations in all fetal heart specimens, contrasted with their high prevalence in adult hearts, supports this hypothesis. While our results do not directly prove a causal relationship, they align with prior literature proposing that biomechanical factors, such as cumulative leaflet stress, turbulent flow, and repeated coaptation, may contribute to the formation of fenestrations over time. These insights into the prevalence, morphology and leaflet distribution of fenestrations provide a valuable foundation for future research investigating their etiology, clinical significance, and potential role in valve dysfunction.