mitral valve size measurement of human heart

Archives of Medicine and Health Sciences / Jul-Dec 2013 / Vol 1 | Issue 2 105

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DOI: 10.4103/2321-4848.123016

Original Article

Introduction

Heart is a vital organ of circulatory system. Valves maintain the unidirectional flow of blood. Mitral valve (MV) prevents the backflow of blood into the left atrium. For the proper functioning of the heart, all valves should be intact. It consists

Corresponding Author: Dr. Kapil Amgain, Department of Anatomy, Jawaharlal Nehru Medical College, KLE University, Nehru Nagar, Belgaum - 590 010, Karnataka, India. E-mail: [email protected]

Kapil Amgain1, Sujit Kumar Thakur1, Rajendrakumar Dundappa Virupaxi2, Daksha Dixit3, Suresh Pitambarappa Desai4, Mohan Gan5

1Post Graduate Student, 2Associate Professor, 3Professor and Head of Department of Anatomy, 4Professor of Anatomy, 5Professor of Cardiothoracic Surgery, Jawaharlal Nehru Medical College, KLE University, Belgaum, Karnataka, India

Mitral valve size measurement in North Karnataka by using cardiac sizer: A cadaveric study

ABSTRACTBackground: Heart is a vital organ of circulatory system. Valves maintain the unidirectional fl ow of blood. Mitral valve (MV) prevents the backfl ow of blood into the left atrium. For the proper functioning of the heart, all valves should be intact. MV prolapse and regurgitation is the main cause of MV replacement. Mean circumference of MV varies from person to person. Aim of the present study is to measure the average size of the valve in the cadavers of North Karnataka region by using cardiac sizer, which would help in the selection of prosthetic valve in the cardiac surgery. Materials and Methods: This study was carried out on 50 cadaveric adult human hearts. Left atrium was opened along the left border of heart so as to expose the mitral orifi ce. Then, the diameter of the valve was measured by using cardiac sizer, whereas circumference was calculated manually. Number of mitral valve cusps and papillary muscles were observed. Results: The mean annular circumference and diameter of the mitral valve was found to be 8.03 ± 0.82 cm and 2.56 ± 0.32 cm, respectively. Majority (72%) of the mitral valves had the circumference ranging from 7.53 to 8.47 cm and the diameter ranging from 2.4 to 2.7 cm. Conclusion: The size of mitral valve in the North Karnataka region was found to be less as compared to the other studies. This study might help cardio-thoracic surgeon as well the prosthetic valve manufacturing companies for the rough estimation of the mitral valve size.

Key words: Circumference of valve, cardiac sizer, diameter of valve, mitral valve

of an orifice and its associated annulus, the cusp, the supporting chordae tendineae, and papillary muscles.[1] Mechanical support is provided by fibro elastic cardiac skeleton. The mean circumference of mitral valve is 9.0 cm in males and 7.2 cm in females.[2] The annulus changes its shape and dimension during cardiac cycle also.[1] So, the aim of the present study is to measure the mitral valve size in formalin-fixed cadaveric hearts. Various heart diseases affect the valves causing stenosis, regurgitation or prolapse of leaflets resulting valve insufficiency. Such cardiac diseases requires repair of the valve and when damage of the valve is more due to disease pathology, valve replacement surgery will be attempted with the artificial valve.[3]

Artificial valve [Figure 1] may be of two types: 1) Biological or Tissue Valve 2) Mechanical or Metal Valve.[4] Tissue valve

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106 Archives of Medicine and Health Sciences / Jul-Dec 2013 / Vol 1 | Issue 2

Amgain, et al.: Mitral valve size measurement in North Karnataka by using cardiac sizer

again is of two three types 1) Homograft (allograft), 2) Autograft, 3) Heterograft (Xenograft). Homograft means transplanting the human cadaveric heart valves in the patient. In autograft patients, own body’s facia lata or pericardium is taken and transplanted in the diseased valve. In case of heterograft, bovine pericardial tissue is taken and transplanted in the diseased person.[5] Mechanical valve are made up of 1) Alloys of stainless steel, 2) Alloys of molybedenum, 3) Pyrolytic Carbon, 4) Silicon, 5) Teflon, 6) Polyester etc.[6] The exact anatomy and measurement of valve are needed for the better selection of prosthetic heart valve.[4]

During mitral valve replacement surgery, surgeons need actual circumference and diameter of the patient’s mitral valve rather than the other details of anatomy of the valve. Many publications dealing with the detailed anatomy are found in literature, but most of them lack the numerical values that were actually needed by the surgeons. So, this study was aimed to measure the size of mitral valve by using the cardiac sizer (which is used by cardiac surgeons) rather than using the measuring tape or vernier calipers. Data of the present study will be helpful to surgeons, anatomist as well as for the prosthetic valve manufacturing company. During mitral valve replacement, the surgeons use the cardiac sizer [Figure 2] to measure the diameter of mitral valve in situ. Accordingly, they choose the size of prosthetic mitral valve for that patient and replace it. So, we also used the cardiac sizer to measure size of mitral valve of the cadaveric heart to know what type and size of prosthetic valve would fit for the population of North-Karnataka.

Since there is variation in measurement of annular diameter and circumference of mitral valve in different studies and lack of similar data of North-Karnataka region, the present study was undertaken for the measurement of size of mitral valve. By considering the above mentioned factors, we had attempted to study the size of mitral valve by using the cardiac sizer for the measurements in cadaveric hearts.

Materials and Methods

A total of 50 adult human hearts without any obvious pathology were obtained from the Department of Anatomy, Jawaharlal Nehru Medical College, Belgaum; then, it was numbered and preserved in 10% formalin solution. These hearts were dissected carefully to visualize the cusps of mitral valve. Diameter of the mitral valve was measured by using the appropriate cardiac sizer after exposure of the of the mitral valve by dissection of left atrial walls [Figure 3], and circumference was calculated manually

by using the formula (C = d). Photographs were taken wherever necessary. Data analysis was done by using the software (SPSS version 20). The results were disseminated in tabular as well as narrative form after analyzing the data by using appropriate statistics.

Figure 1: Prosthetic valve

Figure 2: Cardiac sizer

Figure 3: Measurement of mitral valve by cardiac sizer



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Results

In the present study, annular circumference of mitral valve was found to range from 6.59 to 10.36 cm. Out of 50 cadaveric hearts (irrespective of sex), only 2 (4%) hearts had maximum annular circumference of 10.36 cm, whereas 3 (6%) of them had the minimum circumference of 6.59 cm. Maximum 13 (26%) hearts had the mitral valve circumference of 7.85 cm followed by 8.47 cm (24%) and then 7.53 cm (22%). Majority (72%) of the hearts had the mitral valve circumference ranging from 7.53 to 8.47 cm. Details about the frequency distribution of the valve is shown in Table 1.

Similarly, diameter of mitral valve ranged from 2.1 to 3.3 cm. Twenty six percent of hearts had mitral valve diameter of 2.5 cm followed by 2.3 cm in 20% hearts. Only 6% hearts had the minimum diameter of 2.1 cm, and 2% hearts had the maximum diameter of 3.3 cm. Majority of the hearts (72%) had the mitral valve diameter ranging from 2.4 to 2.7 cm [Table 2].

The mean diameter of mitral valve was 2.56 cm and mean circumference was 8.03 cm, while standard deviation for mean and circumference was 0.32 cm and 0.82 cm, respectively [Table 3].

Discussion

The anatomy of mitral valve has been described in many textbooks, but most of them lack the data in relation

with mitral valve measurements. In the present study, circumference of the valve was found to be ranging from 6.59 to 10.36 cm, and majority (72%) of the cases had the valve circumference ranging from 7.53 to 8.47 cm. Similarly, the diameter of the valve was found to be ranging from 2.1 to 3.3 cm, and the majority (72%) of the hearts had the diameter ranging from 2.4 to 2.7 cm. The observations regarding the mitral valve show variable findings depending upon the method used in study.[7] The diameter and circumference obtained in the present study differs from the previous study[8-15] is shown in the Table 4.

We did’t find similar study measuring the size of mitral valve by using the cardiac sizer in the literature. There are various studies on valve size measurement by dissection method. A study done by dissection method in Maharashtra showed that the average circumference of mitral valve is 9.34 cm.[16] But, in our present study, we found that average size of mitral valve is only 8.03 ± 0.82 cm, which is less than the study done in Maharashtra. Similarly, table 4 showed the comparison of circumference and diameter of mitral valve with various other studies.

Walmsley T.[7] in 1929 mentioned the mitral valve measurements. Later on, it was done by Rusted IE et al.[8] in 1952. The circumference of the mitral valve in the present study [Table 1] was found to be less than the measurements reported by Tetsuro Sakai[14] by dissection method and Ormiston[13] (1981) by 2D echocardiographic method but significantly lesser than findings of Louis A. Du Plessis[11] (1964) in fresh hearts and Brock RC[9] (1952), Bulkley and Roberts[12] (1975), Rusted IE[8]

(1952), and Chiechi et al.[10] (1956) by using dissection method.

In present study, measurements of mitral valve annular circumference fall in range of 7.53 - 8.47 cm, which constitute 72% of total hearts. Only 14% of hearts had the circumference ranging from 9.10 to 10.36 cm [Table 2]. In present study, annular circumference was observed to be less than previous

Table 2: Frequency distribution table of diameter and circumference of mitral valveSr. No. Diameter (d) Calculated circumference (C)=d Frequency Percentage (%)1 2.1-2.3 cm 6.59-7.22 cm 7 14 2 2.5-2.7 cm 7.53-8.47 cm 36 723 2.9-3.3 cm 9.10-10.36 cm 7 14

Table 3: Mean diameter and circumference of mitral valveSr.No. Parameters Mean±S.D. (cm) Range value (cm)1 Diameter of mitral valve 2.56±0.32 2.1 to 3.32 Circumference of mitral valve annulus 8.03±0.82 6.59 to 10.36

Table 1: Annular diameter and circumference of mitral valveSr. No. Diameter (d) of

Mitral valve (cm)Calculated

circumference (cm) (C=d)

Number of specimen

Percentage (%)

1 2.1 6.59 3 6.02 2.2 6.90 2 4.03 2.3 7.22 2 4.04 2.4 7.53 11 22.05 2.5 7.85 13 26.06 2.7 8.47 12 24.07 2.9 9.10 3 6.08 3.1 9.73 3 6.09 3.3 10.36 1 2.0Total hearts 50 100%

Table 4: Comparison of mitral valve size between previous study and present study Sr. No Name of author Year Circumference Diameter Method of study1 Rusted, I. E et al.[8] 1952 9.9 2.5 Dissection method2 Brock RC[9] 1952 10.05 3.20 Dissection method3 Chiechi et al.[10] 1956 10.00 3.18 Dissection method4 Louis A

and Du Plessis[11]

1964 10.10 3.21 Dissection method

5 Bulkley and Roberts[12] 1975 9.00 2.86 Dissection method6 Ormiston JA[13] 1981 9.30 2.96 2D echocardiography7 Tetsuro Sakai[14] 1990 9.33 2.97±0.35 Dissection method8 Sakai T[15] 1999 9.33 2.23 Dissection method9 Patil et al.[17] 2009 8.248 — Dissection method10 Gunnal et al.[18] 2012 9.12 2.22 Dissection method11 Present study 2013 8.03±0.82 2.56±0.32 Cardiac sizer

after dissecting



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observations given by different authors.[8-15,17] Louis in 1964 stated data of the dimensions of the valve, which may be of interest to anatomists and surgeons.[11] Normal measurements of the component parts of the mitral valve will help the surgeon to assess the exact mechanical reason for valve insufficiency. Vander Spuy[19] in 1964 found that the detailed anatomical and functional features are essential in the manufacture of an entirely anatomical whole mitral valve from autogenous tissues. The data assessed in the present study can be used for manufacturing mitral valves. From the observational study, we found that mitral valve complex has two cusps, among which anterior one is triangular and posterior is quadrangular in shape. Posterior leaflet had two papillary muscles, whereas anterior has only one. And, the papillary muscle of posterior cusps is larger than the anterior one, which is found to be similar with the study done by Muresian H et al.[20]

Conclusion

The size of mitral valve in the North Karnataka region was found to be less as compared to the other studies. This study might help cardio-thoracic surgeon as well the prosthetic valve manufacturing companies for the rough estimation of the mitral valve size.

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Churchill Livingstone; 1999. p. 1006-8.2. Ranganathan N, Lam JH, Wigle ED. Morphology of human

mitral valve II. The valve leaflets. Circulation 1970;41:495-67.3. Menon RG, Al Delamie T, Valliathu J, Zacharias S, AI Lawati A,

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4. Catherine OM, Lenehan A, Ginsburg V. Textbook of valvular heart disease. 2nd ed. Elsevier, Philadelphia,1999. p. 513.

5. Bulkley BH, Roberts WC. Dilatation of the mitral anulus. A rare cause of mitral regurgitation. Am J Med 1975;59:457-63.

6. Brownlee, RT, Yates AK. A fascia lata mitral valve based on the ‘frustum’ principle. Thorax 1971;26:284-7

7. Walmsley T. Quain’s Elements of Anatomy. 11th ed. In: Bryce TH, Walmsley T, editors. Vol. 4. The Heart. London: Longmans, Green; 1929. p. 3.

8. Rusted IE, Scheifley CH, Edwards JE. Studies of the mitral valve. I. Anatomic features of the normal mitral valve and associated structures. Circulation 1952;6:825-31.

9. Brock RC. The surgical and pathological anatomy of the mitral valve. Br Heart J 1952;14:489-513.

10. Chiechi MA, Lees WM, Thompson R. Functional anatomy of the normal mitral valve. J Thorac Surg 1956;32:378-81.

11. Duplessis LA, Marchand P. The anatomy of the mitral valve and its associated structures. Thorax 1964;19:221-7.

12. Bulkley BH, Roberts WC. Dilatation of the mitral annulus-A rare cause of mitral regurgitation. Am J Med 1975;59:457-60.

13. Ormiston JA, Shah PM, Tei C, Wong M. Size and motion of the mitral valve annulus in man-A two-dimensional echocardiographic method and findings in normal subjects. Circulation 1981;64:113-20.

14. Sakai T, Okita Y, Ueda Y, Tahata T, Ogino H, Matsuyama K, et al. Surgery for a acquired cardiovascular disease, Distance between mitral annulus and papillary muscles. Anatomic study in normal human hearts. J Thorac Cardiovasc Surg 1999;118:636-41.

15. Sakai T, Okiya Y, Tehata T, Ogino H, Matsuyama K, Ueda Y, et al. Distance between mital valve annulus and pappilary muscle: Anatomic study in normal human hearts. J Thorac Cardiovac Surg 1999;118:636-40.

16. Pant P, Mukhia R, Kumari HN, Mukherjee A. Morphological and morphometric analysis of mitral valve in Maharashtra region: Cadaveric study. Indian J Appl Res 2013;3:497-8.

17. Patil DS, Mehta CD, Prajapati PA. Morphology of mitral valve in human cadavers. Internet J Cardiol 2009;7:2.

18. Gunnal SA, Farooqui MS, Wabale RN. Study of mitral valve in human cadaveric heart. Heart Views 2013;12:132-5.

19. Van der Spuy JC. The functional and clinical anatomy of the mitral valve. Br Heart J 1958;20:471-8.

20. Muresian H, Diena M, Cerin G, Filipoiu F. The mitral valve: New insights into the clinical anatomy. Medica 2006;1:80-7.

How to cite this article: Amgain K, Thakur SK, Virupaxi RD, Dixit D, Desai SP, Gan M. Mitral valve size measurement in North Karnataka by using cardiac sizer: A cadaveric study. Arch Med Health Sci 2013;1:105-8.

Source of Support: Nil, Confl ict of Interest: None declared.



mitral valve size measurement of human heart

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