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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 9  |  Issue : 3  |  Page : 115-120

A study of morphology of the chordae tendineae of the left ventricle in human cadaveric hearts of North West Indian population


1 Associate Professor, Department of Anatomy, Faculty of Medicine and Health Sciences, SGT Medical College Hospital and Research Institute, Gurugram, Haryana, India
2 Professor, Department of Anatomy, Faculty of Medicine and Health Sciences, SGT Medical College Hospital and Research Institute, Gurugram, Haryana, India

Date of Submission08-Jul-2020
Date of Decision08-Aug-2020
Date of Acceptance23-Sep-2020
Date of Web Publication15-Oct-2020

Correspondence Address:
Kirandeep Kaur Aulakh
Department of Anatomy, Faculty of Medicine and Health Sciences, SGT Medical College Hospital and Research Institute, Budhera, Gurugram, Haryana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/NJCA.NJCA_13_20

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  Abstract 


The chordae tendineae form an important part of atrioventricular apparatus connecting papillary muscles to the valve leaflets. Gross morphology of the chordae tendineae of the left ventricle was studied, and any gender differences were noted. Material and methods: 30 grossly normal cadaveric fixed in 10% formalin were studied. An incision was given along left border of heart to open the left ventricle. Gross morphology of chordae tendineae were studied. Statistical analysis: In the anterior leaflet, two strut chordae were found in both males and females in all the cases. The posterior leaflet of mitral valve showed the presence of rough zone, cleft, and basal chordae. Cleft and basal chordae were seen only in the posterior leaflet of mitral valve and not in the anterior leaflet. The number of rough zone chordae was more in the posterior leaflet than other types of chordae, and they were always present. The extent of the spread of anterolateral commissural chorda was mainly to commissural 1/3 of valve leaflet. In males, the chorda spread to commissural 1/3 of leaflet in all the cases, while in females, it was so in 86.7% of cases only. Posteromedial commissural chorda was present in 96.7% of cases.

Keywords: Basal chordae, chordae tendineae, cleft chordae, commissural chordae, rough zone chordae


How to cite this article:
Aulakh KK, Aneja PS, Garg S. A study of morphology of the chordae tendineae of the left ventricle in human cadaveric hearts of North West Indian population. Natl J Clin Anat 2020;9:115-20

How to cite this URL:
Aulakh KK, Aneja PS, Garg S. A study of morphology of the chordae tendineae of the left ventricle in human cadaveric hearts of North West Indian population. Natl J Clin Anat [serial online] 2020 [cited 2020 Nov 28];9:115-20. Available from: http://www.njca.info/text.asp?2020/9/3/115/298158




  Introduction Top


Mitral valve apparatus consists of left atrioventricular orifice and its annulus, two valve leaflets, chordae tendineae, and two papillary muscles. Function of the valve is dependent on the anatomic and mechanical structure of all these parts.[1]

The chordae tendineae form an important part of this apparatus connecting papillary muscles to the valve leaflets. Chordae tendineae rupture will lead to mitral incompetence due to loss of support to the valve leaflet.[2],[3] In mitral incompetence, repair should include restoring the chordae also. It requires knowledge of type of repair and the number of chordal substitutes for reimplantation.[4] There is thickening and fusion of chordae in rheumatic mitral stenosis which leads to disturbances in their functioning. Valve leaflets are unable to open during diastole. This gains importance when the deformity is to such an extent that the function of the valve gets disrupted and clinical symptoms appear. There are deficiencies in our present knowledge of the chordae tendineae of human hearts. This study was done with an aim to overcome this deficiency.

Mitral valve has two leaflets. It is a continuous attachment around the entire mitral orifice rather than two distinct leaflets.[5] Its free edge has dips. There are two deep and constant indentations called anterolateral and posteromedial commissures. The chordae attached here are called commissural chordae.

The anterior leaflet is semicircular or triangular. The leaflet shows two zones. There is a deep crescentic rough zone and a clear zone. The anterior leaflet has no basal zone. The posterior leaflet usually has two clefts. The posterior leaflet does not have strut chordae among its rough zone chordae.[6] It has rough, clear, and basal zones.

True chordae of mitral valve consist of anterolateral or posteromedial commissural chordae and other types of leaflet chordae.[6] Rough zone chordae are seen which include strut chordae. The posterior leaflet has rough zone, cleft, and basal chordae. Anterolateral and posteromedial commissural chordae arise by a single stem fanning out at once into radiating strands attached to the smooth free margin of the commissure.

The anterior leaflet has two specific chordae. They are quite thick and sturdy. They come from tips of anterolateral and posteromedial papillary muscles to attach near line of valvar closure posteromedially (4–5 o'clock position) and anterolaterally (7–8 o'clock position), respectively. They are strut chordae, visible in over 90% of the hearts.[6] Their zone of attachment was earlier termed as the critical point of tendinous insertion of the anterior leaflet.[7]

Most true chordae have a single stem and divide into branches soon after their origin from papillary muscle. Fan-shaped chordae have short stems and branch profusely to attach to the valve leaflets. Rough zone chordae usually have a single stem which splits into three strands. Basal chordae are solitary cords and pass from the ventricular wall to the valve leaflet.[8]

False chordae tendineae of mitral valve are irregularly distributed. They have been named left ventricular bands and often cross the outflow tract.[8] They have been associated with a vibratory functional heart murmur in young adults.

Aims and objectives

  1. To note the number, attachment, and shape of the chordae tendineae of mitral valve
  2. To note the gender differences between the gross morphology of the chordae tendineae of mitral valve.



  Materials and Methods Top


The study material included thirty adult grossly normal-looking cadaveric hearts. The work was done in the Department of Anatomy, Government Medical College and Hospital and Postgraduate Institute of Medical Education and Research, Chandigarh. The geographic region covered includes Punjab and Haryana states of India. The study was done over a period of 1½ years as part of compulsory postgraduation thesis. Gender distribution for the study included 17 male and 13 female hearts. The study was done on donated cadavers used for graduate and postgraduate teaching and dissection. Therefore, ethical clearances had been taken before the start of the study.

Inclusion criteria

Apparently, grossly normal hearts were included without any visible malformation or disease.

Exclusion criteria

Hearts with gross visible malformations or diseases were excluded.

10% formalin-fixed hearts were taken. Running tap water was used to wash off excess formalin. The heart was opened along its left border. This is done to avoid damaging the papillary muscles. The posterior leaflet of mitral valve was cut in the middle. Any blood clots were removed under running tap water. The chordae tendineae were studied with the help of a table lamp with Magna Vision with special attention to their type, origin, number at origin, attachment on the leaflet, level of branching, and direction of the stem. To standardize the concept of chordal insertion, the point of insertion was defined as that point on the leaflet at which a chorda began its attachment, irrespective of the extent of that attachment.

Statistical analysis

An unpaired t-test was used to compare the chordae tendineae to find if there are any sexual differences. The results were compared with another similar study.


  Results Top


Anterior leaflet

The number, shape, and branching pattern of the chordae tendineae of the anterior leaflet of mitral valve found in the present study are shown in [Table 1]. Two strut chordae [Figure 1] were found in both males and females in all the cases by us. However, out of them, 1.7% were atypical with one cord and 6.7% were atypical with two cords. Lam et al.[6] observed strut chordae in more than 90% of the hearts. They appear to have ignored strut chordae with one or two cords, which may account for the difference in the two studies.
Table 1: Chordae tendineae of the anterior leaflet of mitral valve

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Figure 1: Two strut chordae. They are a type of rough zone chordae typical to the anterior leaflet of mitral valve

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Posterior leaflet

The number, shape, and branching pattern of the chordae tendineae of the posterior leaflet of mitral valve found in our study are tabulated in [Table 2]. The posterior leaflet of mitral valve showed the presence of rough zone [Figure 2], cleft, and basal chordae. Cleft and basal chordae were seen only in the posterior leaflet of mitral valve and not in the anterior leaflet.
Table 2: Chordae tendineae of the posterior leaflet of mitral valve

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Figure 2: Fan-shaped anterolateral commissural chorda (black arrow). Rough zone chorda is marked by red arrow, splits into three strands inserting into free edge of leaflet, rough zone of leaflet, and an area midway between them

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Commissures

The attachment, branching, spread, and position of stem of commissural chordae of mitral valve found in our study are tabulated in [Table 3]. The anterolateral commissural chorda [Figure 2] was seen in all the cases in the present study. The extent of the spread of anterolateral commissural chorda was mainly to commissural 1/3 of valve leaflet. In males, the chorda spread to commissural 1/3 of leaflet in all the cases, while in females, it was so in 86.7% of cases only. In females in a few cases, it spread to the middle 1/3 (23.1%) and apical 1/3 (7.7%) of valve leaflet. This difference was statistically significant (P < 0.05).
Table 3: Chordae tendineae of commissures of mitral valve

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Posteromedial commissural chorda was present in 96.7% of cases in the present study. It was present in all the cases in females, while in males, it was present in only 75% of cases. This difference was statistically significant (P < 0.05). The stem of posteromedial commissural chorda pointed toward commissure in 96.6% of cases and toward the anterior leaflet in 3.4% of cases in the present study.


  Discussion Top


The present study followed the classification given by Lam et al.[6] Two anatomically distinct types of fan-shaped chordae-cleft and commissural are found in the mitral valve. There are two commissural chordae in the mitral valve, i.e., anterolateral and posteromedial commissural chordae. The fan-like arrangement of the commissural chordae would help the anterior and posterior leaflets to come into contact with the commissural region by hinge-like movements. Because of its position, the posteromedial commissural chorda would be a more accurate guide in performing commissurotomies.[9] In the anterior leaflet of mitral valve, two types of chordae were identified: rough zone and strut chordae, whereas the posterior leaflet had three types of chordae: rough zone, cleft, and basal chordae.

The chordae tendineae of mitral valve in the present study are compared with a study of Lam et al.[6] in [Table 4].
Table 4: Gender differences in distribution of the chordae tendineae of mitral valve

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Although Lam et al.[6] identified the two types of chordae in the anterior leaflet, i.e., rough zone and strut chordae, they have counted them together. In the present study, the two have been counted separately. As a result, the number of rough zone chordae was less in the present study as compared to that of Lam et al.[6]

The number of rough zone chordae was more in the posterior leaflet than other types of chordae, and they were always present. The cleft and basal chordae were absent in some cases in the present study but not in the other study.[6]

The anterolateral commissural chorda was present consistently in our study as well as in the study by Lam et al.[6] Posteromedial commissural chorda was present in 96.7% of cases in our study, while it was present in all the cases in the study by Lam et al.[6]


  Conclusions Top


Atrioventricular valve repair may be preferred by cardiac surgeons instead of valve replacement.[10] Chordal replacement or repair has proved to be very useful in mitral valve repair.[11] A detailed knowledge of morphology of AV valves, therefore, is important while performing surgeries.

The chordae tendineae of mitral valve were studied in detail with regard to their number at origin, attachment, branching pattern, extent of spread of commissural chorda, and position of central stem of commissural chorda. The comparison with the other studies done in Caucasians shows a markedly similar result as far as the gross morphology, and the number of chordae tendineae is concerned.

On an average, more number of rough zone chordae are attached to the posterior leaflet of mitral valve than to its anterior leaflet. The number of unbranched chordae was more in females. This difference was statistically significant. Atypical rough zone chordae showing one or two cords were seen more commonly in the anterior leaflet than in the posterior leaflet of mitral valve. Furthermore, atypical rough zone chordae with one cord were more frequent than those with two cords in both the leaflets.

In males, the anterolateral commissural chorda spread to commissural 1/3 of leaflet in all the cases, while in females, it was so in 86.7% of cases only. Statistically, this is significant (P < 0.05). In females, the chorda spread to middle 1/3 of valve leaflet in 23.1% of cases, but this was not seen in males. This is significant (P < 0.05).

The extent of the spread of anterolateral commissural chorda in the present study was mainly to commissural 1/3 of leaflet, while posteromedial commissural chorda spread to commissural 1/3 and middle 1/3 of valve leaflet in equal number of cases. This shows that the posteromedial commissural chorda was larger than anterolateral commissural chorda. The greater spread of the posteromedial commissural chorda with the short height of valvular tissue in this area would make this region more susceptible to mitral regurgitation.[9],[12]

There are so many variations of the chordae tendineae that they may be considered as being unique to an individual. This has been observed by a previous study also that no two mitral valve complexes have the same architecture.[13]

A need has been felt for linking of the tissue mechanics and microstructures for the human chordae tendineae. There are limited investigations regarding the chordae-leaflet.[14] This study has tried to overcome such shortcomings. A better understanding of the morphology of the chordae tendineae will lead to improved therapies and treatment outcomes.

Acknowledgments

I am deeply indebted to Dr. Balbir Singh, Professor and ex-HOD, Department of Anatomy, Government Medical College, Chandigarh, for his constant guidance, help, and support. I am grateful to Dr. Kanchan Kapoor, Prof. and HOD, and Dr. Mahesh Sharma, Prof., Department of Anatomy, GMCH, Chandigarh. I am extremely thankful to Dr. Daisy Sahni, Prof. and HOD, Department of Anatomy, PGIMER, Chandigarh, for her help in this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Burch GE, DePasquale NP, Phillips JH. The syndrome of papillary muscle dysfunction. Am Heart J 1968;75:399-415.  Back to cited text no. 1
    
2.
Roberts WC, Braunwald E, Morrow AG. Acute severe mitral regurgitation secondary to ruptured chordae tendineae: Clinical, hemodynamic, and pathologic considerations. Circulation 1966;33:58-70.  Back to cited text no. 2
    
3.
Ronan JA Jr., Steelman RB, DeLeon AC Jr., Waters TJ, Perloff JK, Harvey WP. The clinical diagnosis of acute severe mitral insufficiency. Am J Cardiol 1971;27:284-90.  Back to cited text no. 3
    
4.
Victor S, Nayak VM. Variations in the papillary muscles of the normal mitral valve and their surgical relevance. J Card Surg 1995;10:597-607.  Back to cited text no. 4
    
5.
Harken DE, Ellis LB, Dexter L, Farrand RE, Dickson JF. The responsibility of the physician in the selection of patients with mitral stenosis for surgical treatment. Circulation 1952;5:349-62.  Back to cited text no. 5
    
6.
Lam JH, Ranganathan N, Wigle ED, Silver MD. Morphology of the human mitral valve. I. Chordae tendineae: A new classification. Circulation 1970;41:449-58.  Back to cited text no. 6
    
7.
Brock RC. The surgical and pathological anatomy of the mitral valve. Br Heart J 1952;14:489-513.  Back to cited text no. 7
    
8.
Standring S, Editor-in-Chief. Gray's Anatomy. The Anatomical Basis of Clinical Practice. 41st ed. Philadelphia: Elsevier Limited; 2016. p. 1003-10.  Back to cited text no. 8
    
9.
Ranganathan N, Lam JH, Wigle ED, Silver MD. Morphology of the human mitral valve. II. The value leaflets. Circulation 1970;41:459-67.  Back to cited text no. 9
    
10.
Ratnatunga CP, Edwards MB, Dore CJ, Taylor KM. Tricuspid valve replacement: UK Heart Valve Registry mid-term results comparing mechanical and biological prostheses. Ann Thorac Surg 1998;66:1940-7.  Back to cited text no. 10
    
11.
Reddy VM, McElhinney DB, Brook MM, Silverman NH, Stanger P, Hanley FL. Repair of congenital tricuspid valve abnormalities with artificial chordae tendineae. Ann Thorac Surg 1998;66:172-6.  Back to cited text no. 11
    
12.
Chiechi MA, Lees WM, Thompson R. Functional anatomy of the normal mitral valve. J Thorac Surg 1956;32:378-98.  Back to cited text no. 12
    
13.
Gunnal SA, Wabale RN, Farooqui MS. Morphological study of chordae tendinae in human cadaveric hearts. Heart Views 2015;16:1-2.  Back to cited text no. 13
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14.
Ross CJ, Zheng J, Ma L, Wu Y, Lee CH. Mechanics and Microstructure of the Atrioventricular Heart Valve Chordae Tendineae: A Review. Bioengineering (Basel) 2020;7:25.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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