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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 11  |  Issue : 3  |  Page : 159-163

Histological Analysis of Coronary Atherosclerosis at Division: A Cadaveric Study


1 Assistant Professor, Department of Anatomy, Autonomous State Medical College, Hardoi, Uttar Pradesh, India
2 Assistant Professor, Department of Anatomy, School of Medical Sciences and Research, Sharda University, Noida, Uttar Pradesh, India
3 Assistant Professor, Department of Anatomy, Shri Shankaracharya Institute of Medical Sciences, Bhilai, Chhattisgarh, India
4 Assistant Professor, Department of Anaesthesia, SGPGI, Lucknow, Uttar Pradesh, India
5 Professor, Department of Anatomy, KGMU, Lucknow, Uttar Pradesh, India

Date of Submission02-Jan-2022
Date of Decision08-May-2022
Date of Acceptance30-May-2022
Date of Web Publication14-Jul-2022

Correspondence Address:
Deepshikha Kori
Department of Anatomy, Autonomous State Medical College, Hardoi, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/NJCA.NJCA_2_22

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  Abstract 


Background: Coronary artery disease is the leading cause of mortality in India and it is predominately due to atherosclerosis. The present study was conducted to determine the prevalence of atherosclerosis in coronary arteries without a history of cardiac disease and to determine plaque location in the coronary arterial system. Methodology: This study was conducted in the departments of anatomy and forensic medicine on 50 adult human hearts which had no history of cardiac disease. The coronary arteries were dissected, and 300 sections were taken from the origin, division, and from the distal end of right and left coronary arteries. These tissues underwent (histological) evaluation to note atherosclerosis. Results: In the present study, out of 50 cases, 40 (80%) had atherosclerosis. The majority of atherosclerosis was present at the division of coronary arteries (18.6%). Seventy-two percentage of atherosclerosis is present at left coronary artery (LCA) division (bifurcation) and 40% at right coronary artery (RCA) division (bifurcation). Grade I atherosclerosis was observed in 18.3% of hearts, grade II in 7%, and grade III in 2% of specimens, respectively. Both RCA and LCA had a higher proportion and grade of atherosclerosis at bifurcation points than proximal and distal segments. Conclusion: The proportion and grade of atherosclerosis are significantly higher at the division of coronary arteries without a history of cardiac disease. The identification of high-risk areas for atherosclerosis will lead to future advances in locally oriented preventive strategies.

Keywords: Atherosclerosis, bifurcation, coronary artery, plaque


How to cite this article:
Kori D, Singh R, Singh P, Prasad G, Rani A, Verma R, Kumar N. Histological Analysis of Coronary Atherosclerosis at Division: A Cadaveric Study. Natl J Clin Anat 2022;11:159-63

How to cite this URL:
Kori D, Singh R, Singh P, Prasad G, Rani A, Verma R, Kumar N. Histological Analysis of Coronary Atherosclerosis at Division: A Cadaveric Study. Natl J Clin Anat [serial online] 2022 [cited 2022 Oct 6];11:159-63. Available from: http://www.njca.info/text.asp?2022/11/3/159/350921




  Introduction Top


Coronary artery disease due to atherosclerosis is the leading cause of mortality worldwide and is responsible for one-third of all deaths. In the year 2000, approximately 1.3 million Indians died of this disease, and in 2015, the projected deaths from coronary artery disease were 2.95 million, of which 45% were <40 years.[1]

Atherosclerotic plaques are liable to appear at specific areas in the coronary arteries where blood flow is disrupted, specifically at the areas of low shear.[2],[3] Coronary branch points are remarkably susceptible to atherosclerosis because noticeable hemodynamic alternations occur at bifurcations within the arterial tree. A bifurcation is defined as a division of a main, parent branch into two daughter branches of at least 2.0 mm. Stenoses, or narrowing, located in a main coronary artery and an adjoining side-branch vessel is called a bifurcation blockage or bifurcation lesion. A coronary bifurcation lesion occurs at or near a division of a major coronary artery. Characterizing bifurcation lesions involves assessing the lesion morphology in three important anatomic segments: (1) proximal main branch, (2) distal main branch, and (3) side branch. Bifurcation lesions are common and there is a need to focus on these specific sites.

Coronary bifurcation disease is a very challenging subset in interventional cardiology. Therefore, this research is an effort to histologically determine plaque location in coronary arterial system in cadaveric hearts. The objective was to determine the prevalence of atherosclerotic plaque at bifurcation of main coronary arteries in hearts without any documented history of cardiac disease.


  Materials and Methods Top


The present study was a cross-sectional observational study from September 2015 to August 2016. This study was conducted on 50 adult human hearts of both sexes (35 males and 15 females) in the Department of Anatomy and Forensic Medicine, KGMU, Lucknow, India. The mean weight of cadaveric heart was 271.78 g. All cases in the age group of 16–70 years with a history of death due to natural or unnatural causes without any documented cardiac ailments were included in the study. Decomposed bodies and cases with death due to any cardiac disease, toxin, or history of chest pain were excluded from the study. The study was approved by Institutional Ethics Committee (letter no. 7932/Ethics/R. Cell-15 dated 4/12/15 issued by Institutional Ethics Committee, KGMU, Lucknow).

The hearts were dissected out from the bodies along with a portion of ascending aorta. After dissecting the left coronary artery (LCA) and right coronary artery (RCA), sections were taken at the proximal end of LCA (just after the origin), at the mid of the division between left anterior descending (LAD) and circumflex artery, at the distal end of LAD artery, proximal end of RCA (just after the origin), at the middle of the division between posterior descending artery and RCA, and at the distal end of posterior descending artery. Overall, 300 sections were taken from origin, bifurcation, and distal end of right and left coronary arteries. Histological slide preparation was carried out from these arterial sections. The sections were examined under the microscope to note the presence and site of atherosclerosis and for microscopic assessment of atherosclerotic plaque.

We classified atherosclerotic changes into four grades:

  • Grade 0: No atherosclerotic changes
  • Grade I: <25% narrowing of lumen with atherosclerotic changes present at the arterial wall. Minimal changes, fatty streaks, and preatheroma seen
  • Grade II: 25%–50% narrowing of lumen atherosclerotic changes and atheroma or fibroatheroma
  • Grade III: >50% narrowing of lumen atherosclerotic changes and hemorrhage or thrombosis or calcification present.


Statistical analysis

The categorical variables are presented in number and percentage (%). Association between the variables was assessed using the Chi-square test/Fisher exact test (when in any cell, the expected frequency was <5). To test the inter-rater agreement between two observers, when the observation was in ordinal scale (Grade I, Grade II, and Grade III), weighted kappa, its 95% confidence interval was calculated. Similarly, intra-observer agreement for the assessment of grades in repeated observation was calculated using intraclass correlation. Statistical Package for the Social Sciences software version 23 (SPSS-23, IBM, Chicago, Illinois, USA) and MedCalc Statistical Software version 20 (MedCalc Software, Ostend, Belgium) was used for the data analysis.


  Results Top


In the present study, out of 50 cases, 40 (80%) had atherosclerosis. A total of 300 segments were evaluated which include proximal, division, and distal segments. The majority of atherosclerosis was present at the division. Overall grade I was observed in 18.3% of hearts, grade II in 7%, and grade III in 2% of specimens, respectively. At RCA, the proportion and grade of atherosclerosis were higher at division than proximal and distal segments. At the proximal segment, 14% had grade I atherosclerosis. No atherosclerosis was noted at the distal segment, whereas at division, 24% had grade I and 16% had grade II atherosclerosis. None of the cases had grade III in RCA. The association between atherosclerosis and location was statistically significant.(P < 0.001). At LCA too, the proportion of patients with atherosclerosis was minimum at distal location (8%) and maximum at division (72%). At the proximal segment, 30% of cases had atherosclerosis. At proximal and distal segments, all the cases with atherosclerosis had grade I atherosclerosis only, whereas at division, 34% had grade I [Figure 1]a and [Figure 1]b, 26% had grade II [Figure 2]a and [Figure 2]b, and 12% had grade III [Figure 3]a and [Figure 3]b atherosclerosis. Statistically, differences in incidence and magnitude of atherosclerosis were significant among different segmental locations (P < 0.001) [Table 1]. In between two observers, there was good inter-observer agreement (weighted kappa = 0.945 95% confidence interval [CI]: 0.911–0.978, P < 0.001) was found in the assessment of the level of grades. Similarly, intra-observer percent agreements ranged from 95.6% (95% CI: 94.5%–96.5%, P < 0.001) to 97.7% (95% CI: 97.2%–98.2%, P < 0.001) for observer 1 and observer 2, respectively.{Figure 1}{Figure 2}{Figure 3}{Table 1}


  Discussion Top


Out of 50 cases, 40 (80%) had atherosclerosis in this study. There were only ten (20%) hearts that did not have atherosclerosis. Previous studies on coronary atherosclerosis, its prevalence, distribution, and histological findings were compared with the present study in [Table 2]. The highest prevalence of atherosclerosis of more than 80% was noted by Schmermund et al.,[7] by Corrado et al., it was 89.18%.[5] The lowest prevalence was noted by Lau et al., which was 0.74%,[6] by Davies et al., it was 8.9%[13] in noncardiac disease cases. The prevalence of atherosclerosis recorded in the present study, i.e., 80% which corresponds with Joseph et al.,[4] and higher than studies done by Dhruva et al. who found 23.3%[11] and Garg et al., who found 46.4%.[10] A study of intravascular ultrasound virtual histology and multidetector computed tomography done by Papadopoulou et al. found just proximal portion of bifurcations contains high-risk plaques. They found 52% plaque at the proximal segment, 24% atherosclerosis at the bifurcation segment, and 24% at the distal segment.[14] Nakazawa et al. found 88% atherosclerosis at bifurcation in severe coronary artery disease.[15] In the present study, 72% of atherosclerosis is present at LCA division (bifurcation) and 40% at RCA division (bifurcation) in noncardiac heart disease death cases which is higher than Papadopoulou et al.[14] and lower than Nakazawa et al.[15],[16]{Table 2}

The atherosclerotic plaques usually appear at specific zone of the coronary arteries where flow is disrupted, particularly at branch points, where hemodynamic alternations occur maximally. Coronary bifurcations are undoubtedly susceptible to atherosclerosis. It has been proclaimed that local hemodynamic forces such as endothelial shear stress (ESS) have been closely related to the occurrence of atherosclerosis at bifurcation.[17],[18],[19] ESS is a tangential force, expressed in units of force/unit area 2, that is applied to the luminal endothelial layer caused by the friction of blood flow. We can state that atherosclerosis develops, especially in the low-shear stress area. It can occur through the modulation of gene expression and the promotion of endothelial cell dysfunction, leading to increased uptake of lipoproteins and migration of leukocyte endothelial cells. All of these promote to the advancement of atherosclerosis.[20]

Coronary bifurcation disease is a very challenging subset in interventional cardiology. If the high-risk zones of atherosclerosis can be identified previously, it will help in taking preventive measures by the detection of vulnerable plaque that will cause severe damage in future so that a comprehensive assessment of high-risk zones of atherosclerosis, i.e., at division including plaque characterization, could help in optimized interventional strategies and better clinical outcomes.

Limitations of study

Although every attempt was made to include only noncardiac causes of death, it cannot be ascertained completely. During specimen study and during processing of specimen, there may be some artifacts that may influence the results. In addition, our study is limited up to 50 cadavers only, and the results will be more reliable with larger sample size.


  Conclusion Top


Seventy-two percentage of atherosclerosis is present at LCA division (bifurcation) and 40% at RCA division (bifurcation) in noncardiac heart disease death cases. Grade I atherosclerosis was observed in 18.3% of hearts, grade II in 7%, and grade III in 2% of specimens, respectively. Both RCA and LCA had a higher proportion and grade of atherosclerosis at bifurcation points than proximal and distal segments.

Acknowledgments

The authors sincerely thank those who donated their bodies to science so that anatomical research could be performed. Results from such research can potentially increase humankind's overall knowledge that can then improve patient care. Therefore, these donors and their families deserve our highest gratitude.[21]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Madan R, Subramanya H, Jalpota YP. Retrospective analysis of fatal aircraft accident investigation during the period 1975-2004: A reality check. Indian J Aerospace Med 2006;50:34-8.  Back to cited text no. 9
    
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Dhruva GA, Agarwal AH, Sanghvi HK. Atherosclerosis of coronary arteries as predisposing factors in myocardial infarction: An autopsy study. Online J Health Allied Sci 2012;11:1-4.  Back to cited text no. 11
    
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Davies MJ, Bland JM, Hangartner JR, Angelini A, Thomas AC. Factors influencing the presence or absence of acute coronary artery thrombi in sudden ischaemic death. Eur Heart J 1989;10:203-8.  Back to cited text no. 13
    
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Papadopoulou SL, Brugaletta S, Garcia-Garcia HM, Rossi A, Girasis C, Dharampal AS, et al. Assessment of atherosclerotic plaques at coronary bifurcations with multidetector computed tomography angiography and intravascular ultrasound-virtual histology. Eur Heart J Cardiovasc Imaging 2012;13:635-42.  Back to cited text no. 14
    
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Nakazawa G, Yazdani SK, Finn AV, Vorpahl M, Kolodgie FD, Virmani R. Pathological findings at bifurcation lesions: The impact of flow distribution on atherosclerosis and arterial healing after stent implantation. J Am Coll Cardiol 2010;55:1679-87.  Back to cited text no. 15
    
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Kumari TK, Das L, Renuka K, Rajeev R, Raju NK. Microanatomy of left internal thoracic artery and left anterior descending artery: A comparative study. Natl J Clin Anat 2021;10:30-4.  Back to cited text no. 16
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Kimura BJ, Russo RJ, Bhargava V, McDaniel MB, Peterson KL, DeMaria AN. Atheroma morphology and distribution in proximal left anterior descending coronary artery: In vivo observations. J Am Coll Cardiol 1996;27:825-31.  Back to cited text no. 18
    
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Traub O, Berk BC. Laminar shear stress: Mechanisms by which endothelial cells transduce an atheroprotective force. Arterioscler Thromb Vasc Biol 1998;18:677-85.  Back to cited text no. 20
    
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