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P.Dharmendra et al
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CLINICALLY SIGNIFICANT ANATOMICAL VARIATIONS OF THE LEFT CORONARY
IN HUMAN CADAVERIC HEARTS
ARTERY
CLINICALLY SIGNIFICANT ANATOMICAL VARIATIONS OF
THE LEFT CORONARY ARTERY IN HUMAN CADAVERIC
HEARTS
Vol 05 issue 12
Section: Healthcare
Category: Research
Received on: 29/04/13
P. Dharmendra, Takkallapalli Anitha, Seema Madan, PradeepLondhe
Department of Anatomy, Chalmeda Anandrao Institute of Medical Sciences,
Bommakal, Karimnagar, Andhra Pradesh, India
Revised on: 18/05/13
Accepted on: 11/06/13
E-mail of Corresponding Author: [email protected]
ABSTRACT
The anatomy of the coronary vessels has been described in detail for atleast 3 centuries. Detailed
appreciation of the normal origin, course, branching and myocardial distribution of these vessels is vital
so that variations of the normal anatomy can be more easily recognized and applied to clinical practice.
Knowledge of normal anatomy and variations in the branching pattern of coronary arteries is very
important to identify the cause of coronary artery diseases and to perform therapeutic, radio diagnostic
and surgical procedures. Since the left main coronary artery system is the commonly affected vessel
and is the first vessel to show blockages, this study was conducted. 93 formalin fixed hearts were
collected in the department of anatomy over a period of 2010 to 2012 and dissected. Origin, length,
number of terminal divisions and the area of distribution of left main coronary artery was noted. The
present study showed that the left coronary artery originated from left posterior aortic sinus except in
one heart where it originated from right coronary sinus. The mean length of left coronary artery is 9.2
±0.31mm, mean outer diameter was 4.64 ± 1.03.In 58.6% cases it bifurcated, in 35.48% cases it
trifurcated and in 6.45% hearts it tetrafurcated.
Keywords:-Left main coronary artery, variations, tetrafurcation, angiographic anatomy.
INTRODUCTION
The incidence of coronary artery diseases has
seen an increasing trend in developing countries
in the last few decades. The study of variations of
coronary arteries especially the left main
coronary artery can be of immense help to
clinician planning interventional procedures such
as stenting, balloon dilatation or graft surgery,
particularly when there are secondary changes of
calcification, plaque formation and stenosis [1].
In the vast majority of people, there are two main
coronary arteries, right and left, which arise from
separate ostia in the ascending aorta [2].Most of
the area of heart is supplied by the left main
coronary artery. The area irrigated by each of
coronary arteries using postmortem angiography
shows that the left main coronary artery irrigates
68.8% of the cardiac muscle mass, 41.5% by left
anterior descending artery and 27.3% by the left
circumflex artery[3]. These values may vary
depending upon the coronary arterial dominant
pattern.
The left coronary artery arises from the left sinus
of valsalva and courses laterally between the base
of pulmonary trunk and left atrium. The left
coronary artery usually divides into two major
branches, the left anterior descending and left
circumflex arteries. A third branch originates
between the angle formed by the left anterior
descending and the left circumflex arteries and
has
various
names,
including
“ramus
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CLINICALLY SIGNIFICANT ANATOMICAL VARIATIONS OF THE LEFT CORONARY
IN HUMAN CADAVERIC HEARTS
P.Dharmendra et al
intermediate”, “median artery” , “left diagonal
artery” and “straight left ventricular artery [2].
ARTERY
specimens were removed along with them. The
coronary arteries were traced from their origin.
Length and outer diameter of left main coronary
artery were noted using a verniercaliper.
Photographs were taken, all the information was
meticulously tabulated, statistically analysed and
compared with earlier studies. The following
criteria have been taken into consideration.
i).Origin of left main coronary artery.
ii).Length and outer diameter of left main
coronary artery.
iii).Termination of left main coronary artery.
MATERIALS AND METHODS
93 formalin fixed heart specimens were collected
from the department of Anatomy, Chalmeda
AnandRao Institute of Medical Sciences,
Bommakal Karimnagar-Andhra Pradesh, India
over a period of 3 years and preserved in 10%
formalin. Skin incisions were given and thorax
was opened as per instructions of cunningham’s
manual of practical anatomy 15th edition [4].The
great vessels were ligated and the heart
RESULTS
Table : 1 Origin of left main coronary artery
Number of hearts
Name of the artery
Variations
Percentage of
variations
93
Left main coronary artery
Arising from Right coronary sinus
1.07%
Table: 2 Mean length and outer diameter of left main coronary artery
Number of hearts
93
Name of the artery
Mean length in
mm
Mean outer diameter
in mm
Left main coronary artery
9.2 ± 0.31mm
(Range 4 to
15mm)
4.64 ± 1.03 (Range
3.0 to 6.8mm)
Table: 3 Termination of Left main coronary artery into two or more branches
Number of
hearts
Name of the
artery
93
Left main
coronary artery
Bifurcated
Total No.
Trifurcated
Percentage
(%)
54
DISCUSSION
Variations related to the origin and course of
coronary arteries may be benign or malignant [5].
The latter predisposes a person to early vascular
compromise, ischaemia and fatal infarction.
58.06
Total No.
33
Percentage
(%)
35.48
Tetrafurcated
Total No.
Percentage
(%)
6
6.45
Benign anomalies of origin of left coronary
artery include.
i). A single coronary artery arises from the right cusp
and divides into right coronary artery and left
coronary artery, with the left coronary artery
coursing anterior to the right ventricular outflow
tract [7].
Int J Cur Res Rev, June 2013/ Vol 05 (12)
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P.Dharmendra et al
CLINICALLY SIGNIFICANT ANATOMICAL VARIATIONS OF THE LEFT CORONARY
IN HUMAN CADAVERIC HEARTS
ii). A single coronary artery arises from the left cusp
and divides into the right and left main coronaries,
with the right coronary artery coursing posterior to
the aorta.
Malignant anomalies of origin of left coronary
artery include.
i). Malignant left coronary artery: This occurs when
the left coronary artery arises from the right cusp
and courses between the aorta and pulmonary
artery. In this interarterial segment of the artery is
subjected to compression during heavy exercise and
can cause sudden death in young persons or
athletes. Basso [6] considered that the left coronary
artery originating from the right cusp and crossing
between the right coronary artery and aorta was
more dangerous than right coronary artery taking
similar path, as a larger volume of myocardium is
put at risk in the former case.[fig: 1]
The variations in the origin of coronary arteries
may be explained on embryological basis. The first
evidence of coronary vessel development is the
appearance at the beginning of the fifth week of
intrauterine life of a structure like blood islands just
under the epicardium in the sulci of developing
heart [8,10]. According to the theory of Ogden J;
there is a dual origin of coronary arteries, proximal
and distal. The distal portion develops first. It is
comprised of a retiform vascular network, similar to
the capillary network that forms in the other parts
of body. This network develops in the
interventricular and atrioventricular grooves and
forms a complete ring around the developing
vessels (peritruncal ring) and communicates with
the heart chamber and extra cardiac great vessels.
Further development of some vessels and
regression of others, the final coronary pattern
develops. This theory adequately explains the
variations of coronary vasculature [9,10].
In our present study the left coronary artery arose
normally from left posterior aortic sinus and in
1.07% of hearts it arose from right coronary sinus.
ostium was present below the supra ventricular
ridge.[fig:1]
[Table no: 1]
ARTERY
The length of the left main coronary artery in
general varies from 2 to 12 mm but may be upto
30mm. It’s diameter, ranging from 5 to 10 mm is
generally inversely related to its length [2].Green
G.E. et al [11] studied the length of the left main
coronary artery in 50 consecutive autopsy
specimens in which 48% of cases, the length of left
main coronary artery was 10 mm or less and in
remaining 52% cases, the length was up to 25 mm.
the short left main coronary artery explains some
failures of adequate coronary perfusion. During
aortic valve surgery, myocardial perfusion depends
on the placement of one or more cannulas in the
coronary arteries. In this regard, the length of left
main coronary artery prior to its bifurcation is
particularly important. A short main trunk makes
carrying out coronary angiography difficult because
the catheter is inserted into one of the terminal
branches, the opacification of the other branch does
not occur and an incomplete image of the coronary
tree is seen. In the present study, the mean length of
left main coronary artery was found to be 9.2 ±
0.31mm which correlates with the above
observations. [Table no: 2]
Outer diameter of left main coronary artery is
important in estimating the extent and severity of
dilatation in cases of coronary aneurysm,
calcification and stenosis. According to Glagov
theory, the outer diameter of coronary artery dilates
in the early phases of atherosclerosis, when plaque
deposition leads to positive remodeling with
preservation of the vessel lumen[16]
Reg J et al [12] studied all the characteristics of the
main trunk of left coronary artery in 100 autopsy
heart specimens. The diameter of the main trunk
measured at its midpoint was found to be in
between 3 to 7mm with average value of 4.86 ± 0.8
mm. In the present study, the mean outer diameter
measured at its mid point was found to be 4.64 ±
1.03 mm which is close to the above observation.
[Table no: 2]
The termination of left main coronary artery varies
from 2 or more branches and accordingly named as
bifurcation,
trifurcation,
tetrafurcation
and
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P.Dharmendra et al
CLINICALLY SIGNIFICANT ANATOMICAL VARIATIONS OF THE LEFT CORONARY
IN HUMAN CADAVERIC HEARTS
pentafurcation. Banchi. A [13] described the
termination of left main coronary artery varying
between two to three branches with the most
common pattern of the bifurcation being 64%.
Which is close to the observation made in our study
i.e. 58.06% hearts. In 35.48% of our present study,
the left main coronary artery trifurcated, where as
similar observation was also made by cavalcanti JS
in 38.18% of heart specimens [14]. Bapista[15]
observed that the left main coronary artery
tetrafurcated in 6.7% of cases and the similar
observation was found in our study i.e. in 6.45%
cases. [fig: 2][Table no: 3]
The left main trifurcating lesions are generally
treated with bypass surgery and left main
trifurcation disease is more complex than left main
bifurcation disease. Therefore its percutaneous
treatment is expected to have a higher rate of
adverse events like stent thrombosis. Trifurcation
stenting carries a high rate of adverse events and
may need to be reserved for patients who are at a
high risk of bypass surgery or who refuse surgery
[17].
CLINICAL SIGNIFICANCE
Anomalous origin of the coronary artery from the
opposite sinus of valsalva is particularly important
as it has been associated with myocardial ischaemia,
ventricular arrhythmias & sudden death, especially
when the anomalous artery course is interarterial,
intra myocardial or intramural. Surgical repair in the
form of uproofing of the vessel seems to be the most
promising method for this condition. Isolated
coronary hypoplasia, stenosis or atresia are
extremely uncommon and the left coronary system is
usually hypoplastic and ischaemia is frequent in
these conditions. Congenital coronary artery
aneurysms are indistinguishable from those acquired
conditions secondary to other diseases. Major
aneurysms can rupture thrombose or produce
infarction due to thromboembolism.
ARTERY
CONCLUSION
Knowledge of coronary circulation is not only
important for anatomists but also for radiologists
and cardiologists performing angiographies and
shunt surgeries, in diagnosis and treatment of
congenital,
inflammatory,
metabolic
and
degenerative diseases involving the coronary
arteries. The advances made in coronary artery
bypass surgeries and modern methods of
myocardial revascularization led to the present
study.
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ARTERY
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IN HUMAN CADAVERIC HEARTS
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ARTERY