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Uncommon anatomical variation of left internal mammary artery – God created Y graft conduit

Authors:
Vijayanand Palanisamy at Madras Medical Mission
Vijayanand Palanisamy
Bharath Kumar Mohandoss
Bharath Kumar Mohandoss
Bharath Kumar Mohandoss
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Mithun Sundararaaja Ravikumar
Mithun Sundararaaja Ravikumar
Mithun Sundararaaja Ravikumar
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Karthik Raman R
Karthik Raman R
Karthik Raman R
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Abstract

The left internal mammary artery is the most accepted and widely used conduit in coronary artery bypass grafting. This report presents a rare case of very early bifurcation of the left internal mammary artery at the level of the third intercostal space.
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Uncommon Anatomic
Variation of Left Internal
Mammary Artery: God-Created
Y-Graft Conduit
Vijayanand Palanisamy, DNB CTh,
Bharath Kumar Mohandoss, DNB CTh,
Mithun Sundararaaja Ravikumar, MBBS,
Karthik Raman R, DNB CTh,
Anjith Prakash Rajakumar, MRCS, DNB CTh, and
Valikapthalil Mathew Kurian, MCh
Department of Cardiac Surgery, Institute of Cardiovascular
Diseases, The Madras Medical Mission, Chennai, India
The left internal mammary artery is the most accepted
and widely used conduit in coronary artery bypass
grafting. This report presents a rare case of very early
bifurcation of the left internal mammary artery at the
level of the third intercostal space.
(Ann Thorac Surg 2020;109:e113-4)
Ó2020 by The Society of Thoracic Surgeons
The left internal mammary artery (LIMA) has a
greater long-term patency rate than the saphenous
vein for use as a conduit in coronary artery bypass
grafting. Patency of the LIMA is the sole reason for
weighing coronary artery bypass grafting ahead of
percutaneous coronary intervention. Hence harvesting
of the LIMA should be a high priority because this
vessel is the primary conduit of choice for coronary
artery bypass. While harvesting the LIMA, anatomic
variations should always be kept in mind. We present a
rare case of very early bifurcation of the LIMA at the
level of the third intercostal space (ICS).
A 53-year-old man with triple-vessel coronary artery
disease was scheduled for coronary artery bypass
grafting surgery. After sternotomy, we noticed a
prominent branch of the LIMA descending along the
pleural fat pad. On meticulous dissection, we found
that the LIMA branched very early, at the level of the
third ICS (Figures 1 and 2). Both branches were more
than 1.75 mm in diameter. On reviewing the coronary
angiogram in retrograde fashion, we recognized the
early branching pattern of the LIMA merged with
the aortic shadow (Figure 3), which made it difficult
to identify preoperatively. Because the patient had a
lesion-free diagonal and an early obtuse marginal
branch, we discarded the musculophrenic branch
and performed grafting using the superior
epigastric branch to the left anterior descending cor-
onary artery.
Comment
Usually, the LIMA arises from the intrascalenous part
of the subclavian artery, occasionally from the common
origin with the thyrocervical trunk, the scapular artery,
the thyroid artery, or the costocervical artery. The
LIMA courses between the transverse thoracis muscle
and the intercostal muscles. The LIMA branches into
the pericardiophrenic, mediastinal, sternal, pericardial,
anterior intercostal, and perforating branches and ter-
minates at the level of the sixth ICS in the superior
epigastric, musculophrenic, and, rarely, diaphragmatic
branches.
Usually, the LIMA bifurcates at the level of the sixth rib
or the sixth ICS, and very rarely it bifurcates earlier, at the
level of fifth rib or the fifth ICS, according to the litera-
ture.
1-4
In our case, the bifurcation of the LIMA occurred
at the level of the third ICS.
On opening the pleura, identifying those abnormal
bifurcations and preserving those branches may help in
grafting more target vessels, with caution taken
regarding the size of the branches. We could not make
use of the God-created Y-graft conduit because the
Figure 1. Early bifurcation of the left internal mammary artery
before breach of the endothoracic fascia.
Figure 2. Early bifurcation of the left internal mammary artery after
complete dissection.
Accepted for publication Apr 27, 2019.
Address correspondence to Dr Palanisamy, Department of Cardiac Sur-
gery, Institute of Cardiovascular Diseases, The Madras Medical Mission,
4A, Dr J.J. Nagar, Mogappair, Chennai, 600037, Tamil Nadu, India; email:
vetri86@gmail.com.
Ó2020 by The Society of Thoracic Surgeons 0003-4975/$36.00
Published by Elsevier Inc. https://doi.org/10.1016/j.athoracsur.2019.04.111
diagonal and early obtuse marginal arteries were free of
disease.
The advantages of having these abnormal bi-
furcations include aortic bypass grafting (with possible
total arterial revascularization without the need to
create an extra Y limb) and good distal runoff.
Knowledge of anatomic variants may help in strategic
planning for grafting. Our report of an abnormal early
bifurcation of the LIMA alerts cardiac surgeons to this
possible anatomic variant noted while harvesting the
LIMA for bypass grafting. If the size is adequate, we can
make use of this early bifurcation to graft more target
vessels.
References
1. Paliouras D, Rallis T, Gogakos A, et al. Surgical anatomy of
the internal thoracic arteries and their branching pattern: a
cadaveric study. Ann Transl Med. 2015;3:212.
2. Henriquez-Pino JA, Gomes WJ, Prates JC, Buffolo E. Surgical
anatomy of the internal thoracic artery. Ann Thorac Surg.
1997;64:1041-1045.
3. Gupta M, Sodhi L, Sahni D. The branching pattern of internal
thoracic artery on the anterior chest wall. J Anat Soc India.
2002;51:194-198.
4. Puri N, Gupta PK, Mahant TS, Puri D. Bilateral internal
thoracic artery harvesting; anatomical variations to
be considered. Indian J Thorac Cardiovasc Surg. 2007;23:
192-196.
Figure 3. Angiographic image showing early bifurcation of the left
internal mammary artery.
e114 CASE REPORT PALANISAMY ET AL Ann Thorac Surg
GOD-CREATED Y-GRAFT CONDUIT 2020;109:e113-4
... Along its course, the ITA gives rise to branches that supply various structures, including the thymus, breast, mediastinum and sternum [3,5,6]. Typically, it gives rise to several branches, including the anterior intercostal arteries, perforating branches, pericardiophrenic, sternal and mediastinal, and terminates as the superior epigastric artery and musculophrenic artery [1,[7][8][9][10]. Additionally, various cases of accessory internal thoracic vessels have been reported, which may give rise to superficial and deep cervical branches [11,12]. ...
A Rare Bilateral Variation in the Branches of the Internal Thoracic Artery: A Case Report
Article
Full-text available
  • Oct 2023
Background: Anatomical variations and, in particular, arterial variations constitute an important chapter in the learning of Clinical Anatomy. Purpose: The purpose of this report is to describe a rare bilateral anatomical variation in the internal thoracic artery (ITA) in a 60-year-old corpse and to depict its extreme clinical importance in coronary artery bypass surgery. Methods: The rare bilateral aberrant branches of the internal thoracic artery and their course in the thorax were incidentally discovered during routine anatomy dissection of the thorax at the Faculty of Medicine and Medical Sciences of the University of Balamand. The findings were thoroughly documented using digital photography, and the dissection followed the instructions from the “16th Edition of Grant’s Dissector”. Results: In the observed case, the left aberrant branch of ITA descends laterally and gives medial and lateral anterior intercostal branches at the first six intercostal spaces. Conversely, the right aberrant artery, which branches from the ITA, descends laterally and gives medial and lateral branches to every intercostal space in the first five intercostal spaces. Conclusion: This report emphasizes that any unexpected variations in the lateral aberrant branches of the internal thoracic artery may complicate the surgical procedure. Bilateral aberrant lateral branches of the internal thoracic artery constitute rare anatomical variations of the internal thoracic artery and have been rarely reported in the literature. Such a course for aberrant lateral branches in the thorax poses possible lethal complications during several procedures involving the thorax, including basic coronary artery bypass graft, thoracocentesis and intercostal paracentesis and breast reconstruction.
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Surgical anatomy of the internal thoracic arteries and their branching pattern: A cadaveric study
Article
Full-text available
  • Oct 2015
Background: The purpose of this study is to review the anatomic characteristics of internal thoracic artery (ITA) and its branches, in order to pursue the extension of its utilization and avoid intraoperative and postoperative complications. Methods: The study was carried out on anterior chest walls obtained during routine autopsies of 50 specimens (30 male, 20 female). Macroscopic and microscopic dissection was performed and the following were studied: origin, length and termination of ITA, size and distance from the sternum, and types of branches. Results: From the origin to the termination point, the length of the left internal thoracic artery (LITA) varied from 159 to 220 mm; with a mean of 182.60 mm. The length of the right internal thoracic artery (RITA) varied from 150 to 231 mm; with a mean of 185 mm. Four types of branches were distinguished. The RITA mean diameter was 2.31 mm, measured at the 2(nd) intercostal space, while the distance from the sternum was 12.77 mm, measured at the 3(rd) intercostal space. The LITA mean diameter was 1.98 mm with the distance from the sternum measured at 12.01 mm. Conclusions: ITA has become the primary conduit for cardiac bypass surgery; many studies have generated fundamental anatomical knowledge for its clinical utilization, which is always useful in order to avoid intraoperative and postoperative complications.
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Bilateral internal thoracic artery harvesting; anatomical variations to be considered
Article
Full-text available
  • Sep 2007
Introduction Predictable intrathoracic course, anatomical proximity to heart and long-term patency has made Internal thoracic artery (ITA) a conduit of choice in coronary artery bypass grafting (CABG). Its frequent bilateral use has necessitated the need to have a comparative knowledge of surgical anatomy of ITA on both sides. Methods A random study was conducted on 100 adult human cadavers. Sternocostal wall was removed and fixed in 10% formalin and dissected for detailed anatomy of ITA. All observations were expressed as mean ± 2SD and appropriate statistical analysis conducted. Observations ITA originated in common trunk with other branches of subclavian artery in 12% on right side and 4% on left. Mean length of right ITA was 20.15 ± 1.22 cm, left 19.83 ± 1.66 cm in 28% of cases where bilateral ITA terminated in 6th Intercostal space (ICS). On pattern of origin of sternal branches from ITA 3 groups were observed. Group-I-some sternal branches arising from common trunk of ITA on both sides (24%), Group-II-some sternal branches arising from common branch of ITA on one side only (54%), Group-III-all sternal branches arising directly from ITA on both sides (22%). Phrenic nerve crossed anterior to ITA on both sides in 52%, posteriorly in 14% and in remaining it crossed anteriorly on one side and posteriorly on other. Conclusion Variations as described in our study in relations to phrenic nerve, level of bifurcation and sternal blood supply must be kept in mind while harvesting bilateral ITA to reduce risk of sternal dehiscence by preserving the sternal blood supply from common trunk and to prevent post operative phrenic nerve palsy.
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Surgical Anatomy of the Internal Thoracic Artery
Article
Full-text available
  • Nov 1997
  • ANN THORAC SURG
The internal thoracic artery (ITA) has become increasingly important in coronary artery bypass grafting due to the excellent long-term results. This study reviews its anatomic characteristics. The ITAs of 100 cadavers were examined and their origin, relation to the phrenic nerve, presence of lateral costal branch; origin of pericardiacophrenic arteries, length, level and type of ITA termination, relation with the transverse muscle of thorax, collateral parietal branches, and distance between the ITA and sternal margins were studied. The ITA was present in all cases, originating directly from the subclavian artery or from a common trunk with other arteries. Its length was 20.4 cm on average, and the most frequent level of termination was at the sixth intercostal space, existing as a bifurcation in 93% and as a trifurcation in 7%. The pericardiacophrenic artery originated from the ITA in 89%. The lateral costal branch was present in 15% of the cases. The ITA was covered by the transverse muscle of the thorax for 7.5 cm (average) and was crossed anteriorly by the phrenic nerve in 70.0%. Information provided by this study may contribute to knowledge of its anatomic characteristics and in turn help prevent complications in ITA dissections.
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The Branching Pattern of Internal Thoracic Artery On The Anterior Chest Wall
Article
  • Jan 2002
  • J Anat Soc India
The branches of internal thoracic artery (ITA) are well documented in the textbooks of Anatomy. However, during the routine dissections of anterior thoracic wall variations in these branches from their usual description were observed. The present study was conducted to study the branching pattern of ITA, which is the main source of blood supply to the sternum. Thirty formalin fixed specimens of ITA, obtained from adult cadavers were studied. Length of ITA, level of its termination and distribution of its branches were observed. The mean length of ITA was same on both sides (158 mm). It was rectilinear in its course but in 1/3 rd of the cases, it was observed to have a medial concavity. Trifurcation of ITA was seen only in 8.3% specimens where the 3 rd branch supplied the diaphragm, while the bifurcation was seen in 91.7%. The overall mean distance of right and left ITA from sternal margins was 8.28 ± 2.13 mm and 8.26 ± 2.39 mm respectively. Corforming to the usual description, the ITA was observed to give sternal, anterior intercostal (AIC) and perforating branches. Besides these, the sternal branches were found to be arising from intercostal or perforating branches through a common stem. Usually, two AIC braches arise from the ITA and supply the respective intercostal space. Whereas, in the present study besides these the AIC arteries arose by a common stem with sternal branches and with AIC branches of same space or adjacent space. The AIC arteries were absent in upper three spaces in a few specimens and the intercostal space was supplied by a continuation of posterior intercostal artery. These branches of ITA and presence of posterior intercostal artery in the anterior part of intercostal space result in a continued blood supply to anterior thoracic wall after mobilization of ITA.
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