Introduction: Previous studies confirm that there is no anthropometric index of normal Iranian hearts, including diameter of cardiac valve, thickness of myocardial septum and coronary artery variation. The purpose of this study was to assess the anatomical indexes of the human heart and coronary artery in the Iranian population. Methods: The study was performed with 207 adult human hearts in both sexes (182 male and 25 female), fixed in 10% formaldehyde. Myocardial thickness and diameter of heart valves were measured using a Vernier caliper. Assessments of the coronary artery were carried out after removal of the pericardium. Results: Analysis of 207 cadaver coronary arteries showed left coronary artery (LCA) dominance type was present in 6.3% of corpus, and balance was present in 4.3% of corpus, while the largest number (89.4%) had right coronary artery (RCA) dominance. The mean values of the morphometric data are as follows: right atrial wall thickness (2.08 ± 0.04 mm), left atrial wall thickness (2.08 ± 0.04 mm), interatrial wall thickness (4.92 ± 0.08 mm), right ventricular wall thickness (3.35 ± 0.05 mm), left ventricular wall thickness (8.36 ± 0.13 mm), interventricular wall thickness (12.01 ± 0.2 mm), diameter of the aorta (23.6 ± 0.4 mm), diameter of the pulmonary artery (24.94 ± 0.4 mm), large diameter of the mitral valve (34.16 ± 0.27 mm), and large diameter of the tricuspid valve (38.8 ± 0.24 mm). Conclusion: The anatomical knowledge of cardiac indicators and coronary artery data will be helpful and clinically relevant, especially for cardiac surgeons for coronary artery bypass grafting and coronary arteriography.

Anthropometric Study Coronary Arteries Human Heart

The heart is a pyramidal organ that pumps blood through the circulatory system. In humans, the heart is located in the thoracic cavity between the lungs. The heart has four chambers that include the left atrium and right atrium, and the left and right ventricles. The right atrium and ventricle are separated by the right atrio-ventricular valve (tricuspid), while the left atrium is associated with the left ventricle through the left atrioventricular valve (mitral). Interatrial, interventricular, and atrioventricular septae separate the four chambers of the heart1, 2, 3. The internal anatomy of each chamber is important for its function4. The right and left coronary arteries (RCA and LCA, respectively) supply the muscle of the heart that normally originates below the junction between the bulbous and the ascending aorta5. The RCA passes vertically between the right atrium and right ventricle in the coronary sulcus. After reaching the inferior border of the heart, it is placed at the diaphragmatic level of the heart. There are several branches of this artery along this course which include: conus artery (CA), atrial rami (AR), sino-atrial artery (SAA), marginal artery (MA), posterior interventricular artery (PIVA), and atrioventricular artery (AV)1, 2. The LCA is thicker than the RCA and passes between the pulmonary trunk and the left auricle, then descends from behind the pulmonary trunk. Eventually, the LCA artery divides into the anterior interventricular (AIVA) and the left circumflex branches (LCX)1, 6.

Variations in the diameter of the heart valves and the coronary arteries are of clinical interest because these findings can be responsive to problems involved in cardiac surgery and angiography. One of these problems is any inconsistency of the size of the artificial valve of the heart or insertion of coronary passages during angiography7, 8. The purpose of this study was to accurately measure heart valves, measure the thickness of atria and ventricles and the septum between them, and to examine the normal variations of coronary arteries using direct dissection for evaluating and determining qualitative changes in the heart. Current indicators include indexes expressed in reference books that are related to Western and European populations, which are consistent with the height, weight, or anthropometric dimensions of these populations. Therefore, this study can be used for guidance by cardiologists, surgeons and medical practitioners involved in the diagnosis and treatment of heart diseases. These findings were observed following dissection from deaths referred to the Department of Forensic Medicine in Isfahan, Iran.

In the study, 207 hearts from 207 cadavers (182 male and 25 female) were evaluated during gross anatomy examination at Isfahan Medical University (Iran). Postmortem coronary dissection was directly performed in all corpses, with some exclusion criteria such as cardiac disease, endocarditis, and aortic root surgery. Overall autopsies were performed at the Department of Forensic Medicine in Isfahan. These hearts belonged to cases in the age group of 15-50. The hearts were embalmed in 10% formalin.

All hearts were meticulously dissected and first, variations and anomaly of the coronary arteries were noted and photographed along their path. Anatomical indicators of coronary arteries were examined according to the following characteristics:

1. Assessment of coronary artery dominance: Right dominant system (A); left dominant system (B); and balance (C) (Figure 1).

2. Assessment of the origin of the conus artery (CA), derived from the trunk of the RCA, or originated from a separate orifice in the anterior aortic sinus (Figure 2).

Figure 2

3. SAA: derived from the right or left coronary artery, or both; if separated from the right coronary artery, first or second part (Figure 3).

4. AV: Whether derived from the right or left coronary artery (Figure 1)

5. Determination of the branches of diagonal artery (Figure 2C)

6. Determination of the length of the left coronary artery (LCX). It is divided into three types: to the left of the heart (short), between the left side of the heart and crux (moderate), and after the crux (high) (Figure 1A and B, Figure 2C).

7. Passing the left and right coronary artery from the crux region (for assessment of coronary artery dominance) (Figure 1B and Figure 2C).

At this stage, heart indicators such as diameter of the aorta and pulmonary artery, size of the mitral and tricuspid valves, and thickness of the atria and ventricles were examined9, 10, 11.

Thickness of the right atrium = (Thickness of smooth area*+ Thickness of rough area**)/2

*Thickness of smooth area: the thickness of the right atrium in the sulcus terminalis (Figure 4A).

**Thickness of rough area: the thickness of the right atrium in the pectineal area (Figure 4B)

Thickness of the right atrium

Thickness of the left atrium = (Thickness of smooth area*+ Thickness of rough area**)/2

*Thickness of smooth area: the thickness of the left atrium in the orifice of the pulmonary vein (Figure 4C).

**Thickness of rough area: the thickness of the left atrium in the auricle (Figure 4D).

Figure 4

Wall thickness of the right ventricle (RV): For this purpose, an incision was made between the anterior sinus of the pulmonary artery and parallel to the AIVA up to the apex of the heart; then the average thick and thin areas were measured with a caliper (Figure 5 A and B).

Figure 5

Wall thickness of the left ventricle (LV): To determine the thickness of the right ventricle, an incision was made between the anterior and posterior sinuses of the aortic artery and, similar to the right side, continued to the apex of the heart. The thickness was the average of thin and rough areas (Figure 5 C and D).

The mitral and tricuspid valve annulus were measured in all heart evaluations. For this purpose, a divider, thread and a millimeter scale was used. The diameter of heart valves was taken by keeping a thread at the divider border and the distance of the thread was measured with a millimeter scale. This method is simple and does not require complicated tools.

Human cadaver hearts were opened longitudinally through the commissure between the left and right coronary cusps. Subsequently, the specimens were mounted flat and the annular circumference of aortic and pulmonary margin were measured near the cusps. Diameter of the valve was assessed through standard circle mathematics, including the equation C = 2nr (Figure 6).

Figure 6

Analysis of the coronary arteries of 207 cadavers that were dissected in our university showed the LCA dominance type was present in 13/207 (6.3%) of corpus, and balance type in 9/207 (4.3%) of corpus, while the largest number 158/207 (89.4%) had the RCA type of coronary dominance (Figure 1).

The normal distribution of coronal arteries was monitored during the dissection. The findings showed that 77/207 (37.2%) of the arteries were separate from the distinct orifice and 128/207 (61.8%) cases were segregated from the right coronary artery; in 2/207 (1%) of cases, this artery was absent.

In studying the origination of the SAA, the data showed that 129/207 (62.3%) of arteries originated from the first part of the RCA, 39/207 (18.8%) from the second part of the RCA, 25/207 (12.1%) from the LCA, 4/207 (1.9%) from the first part of the RCA and the LCA, and 2/207 (1%) from second part of RCA and LCA; in 8/207 (3.9%), this artery was absent.

In addition, the data showed that 186/207 (89.9%) of the AV arteries stemmed from the right coronary arteries, 19/207 (9.2%) stemmed from the left coronary arteries, and in 2/207 (1%), this artery were absent. There were also differences in the number of diagonal arteries in the dissected samples. The frequency of this artery is shown in terms of numbers (Table 1).

There were differences in the frequency of the lengths of the circumflex artery (LCX) that were measured by coronary dissection (shown in Figure 1 A and B, and Figure 2 C). Thus, according to categorization of this artery, 17.4% (36/207), 56.5% (117/207), and 25.6% (53/207) of the arteries were short, moderate, and tall, respectively. In 0.5% (1/207), the LCX was absent. Also, 4 of the LCX were separated directly from the RCA and placed in the main path after circumvention of the aorta. In studying the passage of the RCA and LCA from the crux region, the findings confirmed that the RCA passed the crux in 163/207 (78.8%) cases, while it was not crossed in 44/207 (21.3%) cases. In the LCA, in 6/207 (2.9%) cases sampled, the arteries crossed the crux area but in 201/207 (97.1%) cases, it did not cross in the majority of specimens. Table 2 shows the results of quantitative assessments, including ventricular wall thickness, atrial wall thickness, interatrial wall thickness, interventricular wall thickness, diameter of the aortic entrance and pulmonary artery, and the large diameter of the mitral valve and tricuspid.

Table 2

Quantitative variables	Mean	SEM
Right atrium wall thickness	2.08	0.04
Left atrium wall thickness	2.08	0.04
Inter atrial wall thickness	4.92	0.08
Right ventricular wall thickness	3.35	0.05
Left ventricular wall thickness	8.36	0.13
Inter ventricular wall thickness	12.01	0.2
Diameter of the influx of the aorta	23.6	0.4
Diameter of the influx of the pulmonary artery	24.94	0.4
Large diameter of the mitral valve	34.16	0.27
Large diameter of the tricuspid valve	38.80	0.24

An investigation of the sex relationship was carried with the above 10 indicators and tests showed no significant differences except in two cases (Figure 7). The two significant cases are as follows:

In addition, age correlation with the top anatomical indicators, except for three, did not show significant differences (p > 0.05). The four significant cases include the following:

With age, the interatrial wall becomes thicker (p < 0.02).

With age, the interventricular wall becomes thicker (p < 0.006).

As age increases, the large diameter of the mitral valve rises (p < 0.01).

As age increases, the large diameter of the tricuspid valve rises (p < 0.002).