The mitral valve, or bicuspid valve, is a complex anatomical structure situated between the left atrium and left ventricle, responsible for unidirectional blood flow during the cardiac cycle. It comprises the annulus, anterior and posterior leaflets, chordae tendineae, and the anterolateral and posteromedial papillary muscles.⁽¹⁾ Precise knowledge of the mitral valve’s morphology is essential for understanding normal cardiac physiology and is of particular importance in surgical interventions such as mitral valve repair or replacement, transcatheter procedures, and valve-sparing techniques.⁽²⁾

Anatomical variation in mitral valve dimensions is influenced by factors such as age, sex, body size, and regional population characteristics.⁽³⁾ While clinical imaging modalities provide functional assessment, morphometric data derived from cadaveric studies offer invaluable structural insights that aid in the design of prosthetic valves, surgical tools, and techniques in cardiac surgery. Despite technological advances, intraoperative complications often arise due to limited understanding of valve geometry and anatomical variability.

Existing literature on mitral valve morphometry is limited in scope and often focused on Western populations.⁽⁴⁾ There is a lack of detailed regional morphometric databases, especially from South Asian populations, which could contribute significantly to designing region-specific surgical prostheses or instruments.

The present study aims to analyze the detailed morphometric parameters of the mitral valve in adult human cadaveric hearts, including annular circumference, valve diameters, leaflet dimensions, chordae tendineae characteristics, and papillary muscle distance. By documenting normal anatomical ranges, this research hopes to enhance anatomical understanding and provide baseline data useful for anatomists, cardiac surgeons, and biomedical engineers.

Study Design and Duration

This was a descriptive cross-sectional cadaveric study carried out in the Department of Anatomy, Lokmanya Tilak Municipal Medical College and General Hospital (LTMMC & GH), Sion, Mumbai, over a period of two years from March 2022 to March 2024. The primary objective of the study was to analyze morphometric parameters of the mitral valve complex in adult human cadaveric hearts and document anatomical variations relevant to surgical, diagnostic, and educational contexts.

Sample Size and Selection

A total of 40 formalin-fixed adult human cadaveric hearts (26 male, 14 female) were selected from the anatomy dissection hall and museum specimens available at LTMMC & GH. The estimated age range of the donors was between 40 to 80 years.

Inclusion criteria:

• Well-preserved adult cadaveric hearts with an intact left atrium, left ventricle, and mitral valve complex.

Exclusion criteria:

• Specimens with gross structural deformities, congenital cardiac anomalies, prior cardiac surgery, valve calcification, or infective/endocarditic changes.

Dissection Procedure

Dissection was performed through a standard anterior left atriotomy. The incision was made along the left atrial wall extending from the atrial appendage to the atrioventricular junction to fully expose the mitral valve. Special care was taken to preserve the anatomical integrity of the:

• Mitral annulus
• Anterior and posterior leaflets
• Chordae tendineae
• Papillary muscles
• Commissures

Residual blood clots, pericardial tissue, and adipose deposits were removed to allow precise measurement of the valve components.

Morphometric Parameters Measured

The following morphometric parameters were assessed using a digital Vernier caliper (Mitutoyo®; accuracy ±0.01 mm), a non-elastic cotton thread, and a flexible measuring tape:

1. Mitral annular circumference (measured using thread along the internal border of the annulus)
2. Anteroposterior diameter (distance from the anterior to posterior margins of the mitral orifice)
3. Transverse diameter (distance between the medial and lateral margins of the annulus)
4. Anterior and posterior leaflet height and width
5. Commissural lengths (anterolateral and posteromedial)
6. Number and length of primary chordae tendineae
7. Distance between anterolateral and posteromedial papillary muscles

Each measurement was taken three times independently by two observers, and the average value was used for analysis to reduce inter-observer variability.

Data Collection and Statistical Analysis

Data were recorded in Microsoft Excel and analyzed using SPSS version 27.0 (IBM Corp.). Descriptive statistics were calculated for all parameters, including mean, standard deviation, minimum, and maximum values. The independent sample t-test was used to assess statistically significant differences in morphometric values between male and female hearts. A p-value < 0.05 was considered statistically significant.

Ethical Clearance

The study was conducted in compliance with ethical standards outlined in the Anatomy Act and the Declaration of Helsinki. Approval was obtained and all cadaveric specimens were handled with full respect and confidentiality as per institutional guidelines.

The morphometric analysis of the mitral valves was performed on 40 formalin-fixed adult human cadaveric hearts, comprising 26 male and 14 female specimens. All specimens had anatomically intact mitral valve complexes with well-preserved structural components.

General Morphometry of the Mitral Valve Complex

Table 1 presents the overall mean values and standard deviations of the key morphometric parameters measured in all 40 specimens.

Table 1: Overall Morphometric Measurements of the Mitral Valve (n = 40)

Comparison Between Male and Female Specimens

To assess anatomical variation by sex, independent sample t-tests were conducted. Table 2 summarizes the statistically significant differences in selected parameters between male (n=26) and female (n=14) hearts.

Figure 1 Comparison of key mitral valve morphometric parameters between male and female cadaveric hearts. Error bars indicate standard deviation. Statistically significant differences (p < 0.05) were observed in all three parameters.

The bar graph comparing the three statistically significant morphometric parameters between male and female cadaveric hearts:

• Mitral Annular Circumference
• Anterior Leaflet Height
• Papillary Muscle Distance

Table 2: Comparison of Mitral Valve Parameters Between Male and Female Cadavers

NS = Not significant (p > 0.05); Significant = p < 0.05

Observations

• The mitral annular circumference, anterior leaflet height, and distance between papillary muscles were found to be significantly greater in males compared to females (p < 0.05).
• Other parameters, such as chordae length, commissural lengths, and leaflet width, showed no statistically significant sex-based differences.
• No congenital anomalies or degenerative changes were noted in any specimen.

The mitral valve is a critical anatomical structure responsible for unidirectional blood flow from the left atrium to the left ventricle. Its unique bicuspid design, comprising anterior and posterior leaflets anchored by chordae tendineae and papillary muscles, demands precise morphometric knowledge for both anatomical education and clinical application. This study aimed to provide foundational morphometric data on the mitral valve using adult cadaveric hearts, with a particular focus on identifying sex-based anatomical variations.

In our findings, the mean mitral annular circumference was 92.6 ± 5.2 mm, comparable to values reported by Misfeld and Sievers, who detailed annular circumferences ranging from 90–95 mm in fixed cadaveric specimens and highlighted the structural complexity of the mitral annulus and its saddle-shaped geometry¹. Our measurements of the anteroposterior (27.1 ± 2.4 mm) and transverse diameters (31.8 ± 2.9 mm) align with prior morphometric and echocardiographic analyses, supporting the use of preserved anatomical hearts as reliable models for teaching and research²⁻³.

The anterior leaflet was observed to be longer and narrower, while the posterior leaflet was shorter but broader — a well-established anatomical principle that facilitates optimal valve coaptation during systole⁴. These dimensions also match echocardiographic findings reported in surgical literature, emphasizing their relevance in mitral valve repair⁵.

Our study also evaluated chordae tendineae number and length (mean: 18.1 ± 2.0 and 19.8 ± 1.9 mm, respectively), supporting ranges described by Schoen and Levy, who noted the role of chordae integrity in valve durability and highlighted the predisposition of chordae to degenerative changes in pathological states⁶. Proper sizing and chordal preservation during surgical procedures are essential to reduce mitral regurgitation risk, as emphasized in surgical reviews⁷.

A statistically significant difference was found in annular circumference, anterior leaflet height, and inter-papillary muscle distance between male and female specimens (p < 0.05). This is consistent with prior studies that indicate larger cardiac chamber dimensions in males, primarily due to differences in myocardial mass and body surface area⁸. These findings underscore the importance of patient-specific valve sizing in prosthetic design, particularly in female patients, to avoid undersizing or suboptimal leaflet coaptation⁹.

The relevance of our findings extends to clinical cardiology and surgical intervention. Morphometric variability plays a key role in transcatheter mitral valve implantation (TMVI) and surgical repair techniques, where accurate understanding of annular geometry and subvalvular structures is vital for procedural success¹⁰. As per recent guidelines, incorporation of anatomical data into 3D modeling, custom prosthetics, and heart team planning has improved outcomes and reduced complications¹¹.

Although our study utilized formalin-fixed hearts, which may introduce slight dimensional shrinkage, prior anatomical research supports their continued use for morphometric reliability when fresh-frozen specimens are unavailable¹². Moreover, our measurements reinforce existing imaging-based models, confirming that cadaveric studies remain an essential complement to in vivo research.

This study provides detailed morphometric data on the mitral valve from adult human cadavers and highlights significant sex-based anatomical differences. The results enhance anatomical understanding and offer valuable implications for cardiac surgery, prosthetic valve design, and anatomical education.

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