Download Unusually Looped and Muzzled Branches of Right Coronary Artery

Online Journal of Health and Allied Sciences
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Mangalore, South India : ISSN 0972-5997
Volume 15, Issue 4; Oct-Dec 2016
-Published Quarterly :
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Case Report:
Unusually Looped and Muzzled Branches of Right Coronary Artery
Authors
Anitha Guru, Senior Grade Lecturer
Naveen Kumar, Assistant Professor
Prasad Alathady Malloor, Associate Professor
Jyothsna Patil, Lecturer
Ashwini Aithal Padur, Lecturer
Department of Anatomy, Melaka Manipal Medical College (Manipal campus), Manipal University. Karnataka, India.
Address for Correspondence
Dr. Naveen Kumar,
Assistant Professor
Melaka Manipal Medical College, Manipal campus
Manipal University, Manipal
Karnataka State,
India.
E-mail: [email protected]
Citation
Guru A, Kumar N, Malloor PA, Patil J, Padur AA. Unusually Looped and Muzzled Branches of Right Coronary Artery. Online J
Health Allied Scs. 2016;15(4):12. Available at URL: http://www.ojhas.org/issue60/2016-4-12.html
Submitted: Sep 9, 2016; Accepted: Dec 15, 2016; Published: Jan 31, 2017
Abstract: Coronary artery disease (CAD) is the major cause
of death in developed countries as it accounts on an average
for 1 of every 5 deaths. Morphological variations of coronary
arterial system is one of the causative factor for CAD.
Anatomical knowledge of all possible variant patterns of
coronary arterial system is imperative in the diagnostic and
therapeutic approach of CAD. We report here a rare branching
pattern of right coronary artery (RCA). The origin of RCA was
normal but the course and branching pattern of it were
atypical. RCA was not occupying its usual position in
atrioventricular (coronary) sulcus and its course was
incomplete. It gave a ventricular branch to right ventricle,
which presented an unusual looping pattern. It terminated as
right marginal artery following its muzzled appearance within
the musculature of the ventricle.
Key Words: Right coronary artery, looped, atrioventricular
groove
Introduction:
The right coronary artery (RCA) is a branch of the ascending
aorta and arises from the right aortic sinus. It lies in relation to
the atrioventricular groove (AVG) submerged in the adipose
tissue of the epicardium. It continues towards the posterior
interventricular groove and often crosses the crux of the heart.
In most of the subjects, the RCA supplies the SA node, AV
node, right atrium, most part of right ventricle excluding the
part along the anterior interventricular groove and the posteroinferior part of interventricular septum.[1]
Coronary artery disease (CAD) is the single most common
cause of death in the developed world. CAD accounts for 1 of
every 5 deaths given the unhealthy food habits, sedentary
lifestyle etc. On an average, the frequency of critical
narrowing of RCA amounts to 30 to 40 %. Hence it becomes
important to understand the variations associated with RCA.
We report here one such case.
Case Report
The heart of an adult male cadaver (aged about 55 years) was
being dissected for the undergraduate medical students. While
dissecting the right side of the heart, a small projection was
seen to rise above the surface of the heart at the upper part of
the border (along the right AVG) of right ventricle. Upon
dissection of the right AVG, it was found unoccupied. On
further probing, atrial branches bearing a proximal origin were
spotted, but no ventricular branches were seen. Exposure of
the upper part of the right AVG revealed the presence of the
RCA (Fig 1a). Its first branch (ventricular) was atypically
looped bearing two bends and passed towards the myocardium
of the right ventricle (Fig 1b). The space underneath the loop
was filled with adipose tissue. It then went astray in the
myocardium of the right ventricle.
RCA further gave rise to many long atrial branches of very
thin caliber which coursed across the AVG and went in to right
atrium (Fig 1b). Few atrial branches coursed along the right
AVG before entering the right atrium. The main trunk then
entered the myocardium of the right ventricle. The ventricular
branches initially coursed superficially in the right ventricular
wall and then passed on to deeper parts. One major branch in
particular (muzzled branch) travelled within the myocardium
of right ventricle parallel to the right AVG, with the elevation
it produced being seen on the surface. It then emerged on to
the surface of the heart and continued as the right marginal
artery.
For the further part, the RCA was not seen in the AVG (Fig 2)
and it did not reach the crux of the heart. The coronary sinus
was the sole relation to the AVG.
1
Figure 1: Dissection of right coronary artery (RCA) in an
isolated heart specimen (a) and closer view of its looped
and muzzled branches (b). The muzzled branch is
continuing as right marginal artery. SVC : Superior vena
cava , AVG- Atrioventricular groove.
Figure 2: Posterior view of the heart showing absence of
right coronary artery (RCA) from atrioventricular
groove (AVG)
Discussion
Number of scientific literatures evidenced the variations in the
origin of coronary arterial system of the heart. But, the unusual
morphology of their branches are quite rare. Yamanaka and
Hobbs in 1990 mentioned that coronary artery anomalies
(CAA) are incidentally discovered during coronary
angiographic study or while performing an autopsy with
incidence rate of 0.64% to 1.3%.[2] In the case we report here,
we discovered the variation during cadaveric dissection. Lluri
et al [3] classify coronary artery anomalies in to 2 main
categories. And both categories pertain to origin of the
coronary artery. One category contains those originating from
the opposite aortic sinus and the other includes those
originating from the pulmonary trunk. Absence of RCA has
been reported by few authors.[4,5] Studies on variant origin of
RCA have been conducted. Elliott et al [6] and Ayalp et al [7]
in their studies involving vast number of subjects enumerate
the variant origins of RCA. Papadopaolos et al [8] discuss
about the agenesis of the RCA ostium. In the present case,
origin of RCA was normal but the variations were seen in its
course and some of its branches.
In the literature review, a looped course of the RCA is reported
by Satija et al.[9] In their reported case, the RCA was found to
loop around the pulmonary trunk. The looping seen in the
present case was not near the pulmonary trunk. The passage of
the ventricular branches within the myocardium may give the
appearance of a myocardial bridge. Angelini et al in their work
in 1999, discuss the consequences of the severity of
myocardial bridge and conclude that in most cases they are a
usual variants.[10]
Olivey et al [11] and Lluri et al [3] elaborate on the
embryological basis for such variations of RCA. Olivey et all
propose that an elaborate interaction of epicardial cells with
myocardial cells leads to the transformation of epicardial cells
into mesenchymal cells, as precursors of building blocks of
coronary vessels.[11] Lluri et al [3] add on that maturation of
developing coronary vessels which includes migration of
smooth-muscle cells, proper arrangement of these cells,
growth of some vessels, and regression of others through
apoptosis. Any abnormalities during this delicate, well
controlled process may lead to congenital coronary artery
anomalies.
Taylor et al [12] postulate that in an anomalous course of right
coronary artery in the sulcus between the pulmonary trunk and
the aorta there is an increased risk of malignant arrhythmias
and sudden death. In the reported case the presence of the
looping above the surface of the heart may also pose similar
increased risks. As said by Lluri et al [3] discrepancies in
reporting suggests that not all myocardial bridges cause
symptoms and symptoms if present usually act secondary to
ischemia. Eckart et al in their 25-year review of autopsies in
military recruits mention that cardiac abnormality accounted
for 51% of sudden deaths in young adults, with coronary artery
abnormality accounting for 61% of it.[13] These reports
provide substantial proof that knowledge of coronary artery
variations and abnormalities are highly important and not to
be ignored. Angelini et al propose that choice of treatment for
such CAA as supported by most of literature is surgical
revascularization.[10] Coronary angioplasty with stent
deployment may be employed here provided normal anatomy
of the concerned coronary artery.
Conclusion
In this case, the branches of RCA present a unique loop and
appears to have gone astray and are muzzled in the
myocardium of the right ventricle. The course of the RCA was
also incomplete and atypical as compared to its normal
anatomy. Such a variation in the course of RCA accompanied
by the unique looping and muzzling pattern is rare. It may pose
a tough challenge to the radiologists and cardiologists in
performing various procedures such as coronary stenting
involving the RCA.
References
1. Standring S; Gray’s anatomy: The Anatomical basis of
clinical practice, Elsevier Churchill Livingstone. 39th
ed; 2005; 996-1018.
2. Yamanaka O, Hobbs RE, Coronary Artery Anomalies in
126,595 Patients Undergoing Coronary Arteriography.
Cathet Cardiovasc Diagn. 1990;21(1):28-40.
3. Lluri G, Aboulhosn J., Coronary Arterial Development:
A Review of Normal and Congenitally Anomalous
Patterns. Clin Cardiol. 2014;37(2):126-30.
4. Roba S. Alhasan, Osama Qaqi, MD, Mahir D. Elder,
MD. An Absent Right Coronary Artery Anomaly.
In: Cath Lab Digest 2012;20(12):46-48.
5. Blaschke F, Zimmermann E, Greupner J, Zohlnhoefer D,
Krackhardt F, Haverkamp W et al. A Rare Case of a
Congenital Single Coronary Artery: Right Coronary
Artery Originating From the Distal Left Circumflex
Artery. Vascular
Disease
Management.
2013;10(11):E244-E247.
6. Elliott GE, Martin AH. Congenital absence of the right
coronary artery with a unique origin of the artery to the
sinu-atrial node: A case study. IJAV 2012;5:120–125.
2
7.
8.
9.
10.
11.
12.
13.
Ayalp R, Mavi A, Serçelik A, Batyraliev T, Gümüsburun
E. Frequency in the anomalous origin of the right
coronary artery with angiography in a Turkish
population. Int J Cardiol. 2002;82(3):253-7.
Papadopoulos DP, Moyssakis I, Athanasiou A,
Anagostopoulou S, Benos I, Votteas VE. Right Coronary
Ostium Agenesis With Absence of The Right Coronary
Artery: A Rare Case Of Non-ST Elevation Coronary
Syndrome, Clin Anat. 2006;19(4):345-6.
Satija B, Sanyal K, Katyayini K. Malignant Anomalous
Right Coronary Artery Detected By Multidetector Row
Computed Tomography Coronary Angiography. J
Cardiovasc Dis Res. 2012;3(1): 40–42.
Angelini P, Villason S, Albert V Chan, Jose G Diez.
Coronary Artery Anomalies: A Comprehensive
Approach, edited by P. Angelini (chapter 4). Lippincott
Williams & Wilkins, Philadelphia O 1999; pp 27-63
Olivey HE, Svensson EC. Epicardial-myocardial
signaling directing coronary vasculogenesis. Circ Res.
2010;106:818–832.
Taylor AJ, Rogan KM, Virmani R. Sudden Cardiac
Death Associated With Isolated Congenital Coronary
Artery Anomalies. J Am Coll Cardiol. 1992;20:640–
647.
Eckart RE, Scoville SL, Campbell CL. Sudden Death In
Young Adults: A 25-year Review Of Autopsies In
Military Recruits. Ann Intern Med. 2004;141:829–34.
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