Untitled Document

ORIGINAL ARTICLE

Year : 2020  |  Volume : 3 |  Issue : 1 |  Page : 14-17

DOI: https://doi.org/10.46319/RJMAHS.2020.v03i01.004

 

Study of level of termination of right coronary artery and its dominance in human cadaveric heart specimens
Lakshmiprabha R1, Ramesh P2*, Shivaleela C3, Kavyashree A N4, Anupama D5
1 Professor and HOD, 2 Tutor Cum Research Scholar, 3,4 Associate Professor, 5Professor, Department of Anatomy, Sri Siddhartha Medical College, SSAHE, Tumkur.
*Corresponding author:
Ramesh Palanisamy, Tutor Cum Research Scholar, Department of Anatomy, Sri Siddhartha Medical College, Sri Siddhartha Academy of Higher Institution, Tumkur 572107, Karnataka. India.
E-mail: drramesh.jasmine@gmail.com
Abstract
Background: Major arterial supply to the heart is by Right coronary artery and its branches. Coronary arteries are also called as vasa vasorum of the heart. According to Gray’s anatomy, 70% of the hearts show Right coronary dominance which indicates that Posterior inter ventricular artery arises from RCA in these cases and in such cases usually RCAs terminate beyond the crux of the heart (In Posterior interventricular sulcus - PIVS).The aim of this study was to find out the levels of termination of Right coronary artery and pattern of coronary dominance. Materials and methods: For this study, 55 human formalin fixed  cadaveric heart specimens were taken from the department of anatomy of SSMC, Tumakuru. Results: Right coronary artery(RCA) terminated beyond the level of the crux of the heart (PIVS) in 35 heart specimens and 72 .2 % were right coronary dominant. Conclusion: Our study results are helpful for the accurate interpretation of advanced radiological techniques like angiography especially the  termination levels of right coronary artery and it acts as a guide to cardiothoracic surgeons for  Coronary artery interventional surgeries and management of IHD.
Keywords: Right coronary artery, coronary dominance, termination levels.
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Introduction
The word coronary is derived from Latin and Greek words co-ro-ne and koro ne which means anything curved or hooked. The word coronary also indicates that anything encircling like a crown.[1]Coronary arteries are the vasa vasorum of the heart and they arise  from aortic sinuses of ascending aorta. Right coronary artery (RCA) and left coronary artery (LCA) arise from anterior aortic sinus and left posterior aortic sinus respectively.[2]
                Coronary Artery dominance (CAD) in the humans was described  more on the basis of origin of posterior interventricular artery (PIVA) which arises from right coronary artery in 67% of individuals  whch is called RCAD and from Circumflex branch of left coronary artery(LCA) in 33% of individuals which is described as LCAD. Coronary occlusion occurs in posterior part of the right coronary artery, beyond the level of crux either in the anastomotic branch or  in PIVA. And the same was neglected in previous cardiothoracic interventions.[3]
                RCA supplies whole of the right ventricle, variable parts of the diaphragmatic surface of the left ventricle, the posterior one third of interventricular septum, right atrium, part of the left atrium, sinoatrial node and atrioventricular node,  bundle of his and part of left bundle branch. The incidence of right coronary artery dominance (RCAD) is 90% and left coronary dominance (LCAD) is 10%.[4]
Minor congenital anomalies among coronary arteries are revealed frequently during cardiac catheterization without any adverse prognosis and also these kind of anomalies revealed gave guidelines for avoiding the complications.[5]
                In order to avoid  irreversible complications like necrosis of the area supplied by the injured coronary arteries and its branches, it is better to know all the relevant and possible variations in the  origin, course, branching pattern, distribution  and termination of coronary arteries.[6]
                Various ethnic and regional studies of coronary artery dominance stated varied percentages. Myocardial Infarction (MI) is commonly noticed in the region supplied by left coronary artery and their branches due to its increased transverse diameter than the RCA. The minor occlusions in the posterior part of the right coronary artery and its branches are neglected  most commonly by the surgeons.[7],[8],[9] The present study was undertaken to study the minimal error area (termination levels of the right coronary artery) details for interventional procedures and also for  better understanding of  termination of RCA in this region. This helps the cardiothoracic surgeons for a planned approach and better outcome.
Materials and Methods
A gross anatomical study of 55 specimens of heart by dissection method was conducted in the Department of anatomy, SSMC, Tumakuru for a period of  4 years. Cadaveric heart specimens without any gross pathology were included for the study  & these were obtained  following  prior permission from  Institutional ethical clearance  Committee. 10 Heart  specimens were taken out after incisions on the fibrous pericardium along with  vessels related to it without damaging the outer surface. Specimens were thoroughly washed in running water and blood clots  were removed from heart chambers without damaging other structures.
                The heart specimen was dissected underwater by conventional methods and the veins accompanying  the arteries were removed for clear visualization of arteries avoiding the confusion. Areas like coronary sulcus, interventricular sulcus dissected meticulously and utmost care was taken at the time of removal of fat from the specimens for the preservation of coronary arteries  & their branches along their complete course.[10]
                The course of the RCA, it’s branching pattern  and it’s levels of termination was noted carefully and photographed. Study details were entered in the excel sheet and data was analysed using Epi- info software. Descriptive statistics was applied to interpret the data.
Results
Total 55  heart specimens were utilised for the study. Table 1 shows the level of  termination of the right coronary artery. 1 terminated at the level of rt border of the heart, in 4 specimens before the crux of the heart (Figure 1), in 5 specimens at the crux of the heart, in 35 (71.42%) specimens, right coronary artery continued as posterior interventricular artery in the posterior interventricular groove beyond the crux of the heart and in 4 specimens the level of termination  was at the  left border of the heart (Figure 2).

Table 1: Termination levels of right coronary artery (RCA)


Termination level of RCA

Number of specimens (N=49)*

Percentage (%)

At the level of the right border

1

2.04

Before the crux of the heart

4

8.16

At the level of the crux of the heart

5

10.20

After the crux of the heart(PIVS)

35

71.42

At the level left border

4

8.16

TOTAL

49

100

Figure 1: Termination of right coronary artery before the crux of the heart.
newor2img1

Figure 2: Termination of right coronary artery after the crux of the heart and near the left border.
newor2img2
newor2img3
Figure 3:  Bar diagram shows the origin of the posterior interventricular artery (PIVA) in our study / coronary dominance

Figure 3 shows the Source of origin of  posterior interventricular artery. Out of 55 specimens studied , PIVA arose from RCA in 39 specimens (72.2%) which  indicates the Right coronary artery dominance (RCAD -72.2% cases) and in 15 specimens (27.3%) PIVA arose from LCA which  indicates the left coronary artery dominance (LCAD- 27.3%) and in 1 case it was arising from both (0.5% - Codominant circulation) .
Discussion
The study of Right coronary artery was done globally by various authors regarding its origin, course, distribution and termination. This study mainly focuses on the levels of termination RCA particularly in the posterior aspect of the  heart, ie in the Right coronary sulcus and Posterior interventricular groove. During angiography and other surgical procedures related to coronary arteries, this study helps in better approach particularly on the posteroinferior aspect of the heart.
1) Level of termination of  Right coronary artery
Table 2: Level of Termination of Right coronary artery in various studies.


Authors

At the right border of the heart (%)

Before the crux of the heart (%)

At or after the crux of the heart(PIVG) (%)

Gray’s anatomy2

10

10

60

Kalpana R et al7

7

3

70

Elururavitheja et al8

13

23

57

Bheemeshpusala et al9

15

22.5

55

Present study

2

8

81

In 81% of the specimens studied, the level of termination of RCA was  at or after the crux of the heart (PIVG)  which was more in comparision with the results of study by Kalpana R et al. (70%), Ravitheja E et al(57%) and Pusala B et al (55%) and also with it’s reference in Grey’s anatomy(Table 2).
In the present study, termination of RCA at the level of right border of the heart was seen in 2% of the specimens which is lesser than the results mentioned by Kalpana et al (7%), Gray’s Anatomy(10%), Ravitheja E et al(13%) and Pusala B et al(15%). The percentage of termination of RCA before the crux of the heart was 8% and was more than the results obtained by  KalpanaR et al (3%) and less than that  in the Gray's Anatomy(10%), Ravitheja E et al(23%) and Pusala B et al (22.5%) (Table 2).
2) Coronary Artery Dominance
In the present study, Right Coronary Artery dominance  was found  more frequently (72.2%) than the left coronary artery dominance(27.3%) similar to that described in Gray’s anatomy. This also correlates with the  previous studies done by Sally P et al (70%  RCAD, 15 % LCAD),12 Moore et al( RCAD -67%), Venkatesh et al( RCAD- 69%) (Table 3)2,3,11

Table 3: Percentage of Coronary artery dominance in different studies.


Authors

RCA dominance (%)

LCA dominance (%)

Gray’s anatomy2

70

20

Moore et al3

67

33

Snell R et al4

90

10

Kalpana R et al7

89

11

Venkatesh K et al11

68.75

16.66

Present study

72.2

27.3

A study by Kalpana R et al shows RCAD of higher percentage (89%) than our study with  RCAD(72.2%) and Richard Snell also documented 90% of RCAD where Rt Coronary arteries  continue as PIVA which is about 20% higher than our study results (Table 3).4,7
Regional variations have been documented in Coronary artery dominance. So before planning the surgical procedures  proper evaluation of the coronary artery dominance and their  termination levels will be helpful in avoiding the minimal errors and failures of procedures thus modifying the outcome of  treatment.
Conclusion
Detailed knowledge regarding the level of termination of Coronary arteries and preponderance of  Coronary dominance will be of great help to Cardiothoracic surgeons. This helps them to manage the Coronary artery related diseases with  sound knowledge & clarity of its anatomy which  yields better outcome in their surgical procedures. This study also aids in better interpretation of angiograms by Intervention cardiologists regarding narrowing or occlusion of the Right coronary artery and its branches and its levels of termination in the posterior aspect of the heart either in Right Atrio Ventricular Sulcus and Posterior Inter Ventricular Sulcus.
Conflict of interest: Nil
Acknowledgements:Nil
Financial support and sponsorship:Nil
References
1. Co-ro-ne. Dorland’s illustrated medical dictionary. 30th edt., Philadelphia : Saunders, 2000:420.
2. Standring S. Gray’s Anatomy:The Anatomical Basis of Clinical Practice. 40thed. Edinburgh, London, New York, Oxford, Philadelphia, St. Louis, Sydney, Toronto, Elsevier, Chirchill Livingstone; 2008: 1017-1023.
3. Moore K L, Dalley A F.Clinically oriented anatomy. 5thEd. Philadelphia: LWW; 2017: 141-161
4. Snell R. Clinical anatomy by regions. 9thEd.Philadelphia: Lippincott Williams & Wilkins; 2012: 79-92.
5. Charles E. Wilkins et al “Coronary Artery Anomalies” A Review of More than 10,000 Patients from The Clayton Cardiovascular Laboratories” Texas Heart Institute Journal 1988;15:166-173.
6. Walmsley R, Watson H, Kirklin JW. Clinical anatomy of the heart. 1stEd. Edinburgh: Churchill Livingstone. 1978:199-214.
7. Kalpana R. A study of principal branches of coronary arteries in human. J AnatSociInd Dec 2003; 52(2):137-40.
8. Ravitheja E, Padmavathi M. A study on variation in the termination of right and left coronary arteries and their clinical significance. Int J Anat Res. 2018;6(3.2):5531-34.
9. Pusala B,Reddy M V. Termination and dominance of coronary arteries: On telangana population. Int J Anat Res. 2017;5(2.1):3735-40.
10. Romanes G, Cunningham D. Cunningham's manual of practical anatomy. 16thEd.London: Oxford University Press; 2019: 49-78
11. Venkateshu KV. Coronary artery dominance. Anat Karnataka Jun 2005;2(1):18-21.
12. Allwork SP. The applied anatomy of the arterial blood supply to the heart in man. AnatSoci Great Britian and Ireland Aug 1987;153:1-16.


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