Tricuspid valve: the anterior leaflet is significantly larger in men

The anatomy of the tricuspid valve: an imperative for restorative surgery

The tricuspid valve plays a central role in right cardiac function, but its precise morphology remains a critical factor for the success of surgical interventions. Tricuspid valve diseases, whether regurgitation or stenosis, are closely linked to pulmonary hypertension and right heart failure. For the surgeon, a detailed knowledge of leaflet dimensions is essential, not only for valve repair, but also when using tricuspid tissue for mitral valve reconstruction.

This descriptive morphometric study was designed to establish precise anatomical references by measuring the height, length, and surface area of the valvular leaflets. The primary objective was to quantify morphological variability — specifically the number and size of the leaflets — on a sample of 50 adult cadaveric hearts. The researchers explored the hypothesis of a systematic dominance of the anterior leaflet and sought to identify any significant biometric differences between sexes, potentially dictated by genetic factors, hormonal factors, or distinct cardiac workload constraints.

Methodology: Morphometric analysis of the tricuspid valve

This cross-sectional and descriptive morphometric study was conducted prospectively on 50 adult human hearts (35 males and 15 females). The specimens, preserved in 10% formalin for an average period of 3 to 6 months, were selected from several medical colleges in Maharashtra, India, via purposive sampling.

The inclusion protocol required structurally normal organs upon macroscopic examination, excluding any visible pathology (rheumatic, degenerative, or infectious), congenital anomaly, or surgical scar. After rinsing and drying, a right lateral incision was performed from the inferior vena cava to the ventricular border to expose the valvular apparatus without damaging the free margins.

All measurements were performed by a single trained observer in a controlled thermal environment (25°C–28°C). Data were collected for each leaflet (anterior, posterior, and septal) according to the following criteria:

• Height: maximum distance between the annular base and the free margin, without traction on the tissue.
• Length: maximum inter-commissural distance along the free margin.
• Surface: planar area measured by tracing on graph paper and validated by mechanical planimeter.

Instrumentation was based on Vernier digital calipers (accuracy ≤ 0.01 mm) systematically zeroed and verified using precision gauge blocks. The surface area was confirmed by a point-counting method on a millimetre grid.

Leaflet morphometry: a constant dimensional hierarchy

Analysis of 50 adult hearts (35 men, 15 women) reveals a uniform valvular architecture: 100% of the specimens presented three leaflets (anterior, posterior, and septal), with no accessory leaflets detected. The anterior leaflet systematically stands out as the dominant structure in terms of surface area and linear dimensions.

Comparative analysis by sex

The study highlights a targeted sexual dimorphism. A statistically significant difference was isolated exclusively for the anterior leaflet (P < 0.01), with dimensions being greater in male subjects. Conversely, no significant disparity was observed between sexes for the posterior and septal leaflets.

Qualitative observations and variability

Beyond quantitative measurements, dissections allowed for the identification of distinct morphological behaviors according to the layers:

• Anterior leaflet: Presents the greatest regularity in its dimensional dominance (height and inter-commissural length).
• Posterior leaflet: Characterized by significant size heterogeneity between specimens, although its height remains generally the most limited of the valvular apparatus.
• Septal leaflet: Presents the greatest structural stability, with minimal variations in shape from one heart to another.

A constant architecture: 100% anatomical compliance

This cross-sectional descriptive study analyzed 50 adult human hearts (35 males, 15 females) preserved in formalin. A major clinical finding emerged: the total absence of numerical variations. Across the entire sample (n=50), no accessory leaflets were detected. Each valve strictly presented three leaflets: anterior, posterior, and septal. This structural homogeneity reinforces classical anatomical models, while providing precise data for surgical planning.

Hierarchy of layers: the anterior giant

Measurements performed via digital calipers and planimeter reveal a strict hierarchy of surfaces. The anterior leaflet systematically dominates with an average surface area of 481.24 ± 82.93 mm². It is followed by the posterior leaflet (338 ± 81.96 mm²) and the septal leaflet (302.04 ± 71.49 mm²). While the anterior leaflet is the largest, the posterior leaflet is distinguished by the greatest variability in size and a generally lower height. The septal leaflet, although the smallest in surface area, presents the most uniform structure of the cohort.

Sexual dimorphism and clinical implications

Statistical analysis reveals significant sexual dimorphism only for the anterior leaflet (p < 0.01), which is markedly wider in men. This difference, potentially linked to the overall cardiac workload, was not found for the posterior and septal leaflets. For the surgeon, these data are crucial when using tricuspid tissue for mitral valve repair, or during annuloplasty procedures where millimetric precision is required.

Limits and perspectives

The study presents inherent limitations due to its design: the use of formalin-preserved hearts (3 to 6 months) may induce tissue shrinkage. Furthermore, the sample of 50 hearts remains modest for universal generalization. The authors emphasize that additional studies using modern in vivo imaging would allow for the refinement of these morphometric constants within a dynamic physiological context.

Summary of results

This morphometric study on 50 hearts confirms the dominance of the anterior leaflet (481.24 ± 82.93 mm²), significantly more extensive in men (p < 0.01), followed by the posterior (338 ± 81.96 mm²) and septal (302.04 ± 71.49 mm²) leaflets. The absence of accessory leaflets highlights a tricuspid structural stability, despite the dimensional variability of the posterior segment.

In concrete terms, for the practitioner:

• Harvest optimization: When using tricuspid tissue for mitral repair, prioritize the anterior leaflet to maximize the available surface area, taking sexual dimorphism into account.
• Anatomical landmark: Rely on the uniformity of the septal leaflet as a stable morphometric base during your surgical or ultrasound evaluations.
• Differential diagnosis: Consider any supernumerary structure as a rare or pathological variant, as the three-leaflet configuration remained constant in this adult population.

Technical lexicon of the study

Chordae tendineae: Fibrous cords connecting the papillary muscles to the valve leaflets, essential for maintaining valvular competence and preventing eversion during systole.

Ebstein's anomaly: Rare congenital malformation affecting the tricuspid valve, mentioned in the study as clinical context for the analysis of morphological variations.

Commissures: Anatomical junction points between adjacent leaflets, used as landmarks to measure the maximum inter-commissural length on the free edge.

Planimeter: Precision mechanical instrument used by researchers to calculate the planar surface area of sheets after their graphic transfer onto graph paper.

Septal leaflet: One of the three segments of the tricuspid valve apparatus, characterized in this series by its uniform structure and an average surface area of 302.04 ± 71.49 mm².

Vernier caliper: Digital measuring device with a resolution of 0.01 mm, used in the protocol to quantify the height and length of valvular tissues.

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