Presence of bicarotid trunk has been previously reported in association with aberrant
right subclavian artery (SCA) with no known in human description of bicarotid trunk
in association with aberrant left SCA. We, hereby, describe one such rare aortic arch
pattern highlighting the association of bicarotid trunk with aberrant left SCA and
direct vertebral artery origin from the right aortic arch leading to four arch vessels,
which to the best of our knowledge has not been reported so far in literature.
The development of aortic arch is a complex process with various congenital anomalies
of aortic arch sidedness and its branching patterns.[1] Most commonly encountered pattern is left-sided aortic arch with three arch branches—brachiocephalic
artery that further gives rise to right common carotid artery (CCA) and right SCA,
left CCA, and the left SCA. This case describes a rare right aortic arch branching
pattern with bicarotid trunk, aberrant left SCA, and direct origin of right vertebral
artery from the aortic arch.
A 7-month-old male infant patient with failure to thrive, suck-rest-suck cycles, and
no cyanosis underwent computed tomography (CT) angiography in view of suspected congenital
heart disease (CHD) on clinical grounds and echocardiography showing large ventricular
septal defect (VSD) with echo dropout between aorta and pulmonary artery. CT angiography
showed type II right sided aortic arch with four arch branches—bicarotid trunk (common
trunk giving rise to bilateral common carotids), right vertebral artery, right SCA,
and aberrant left SCA ([Fig. 1]). Additionally, it showed presence of large VSD with confluent dilated pulmonary
arteries causing narrowing of lower trachea, right main bronchus with ostial occlusion
of right upper lobe bronchus ([Fig. 2]). No patent ductus arteriosus or coarctation was seen with normal origin and course
of coronary arteries.
Fig. 1 Volume-rendered reconstructed computed tomography angiography images (A–C) showing type II right aortic arch (RAA) with four-arch branches—bicarotid trunk,
right vertebral artery, right subclavian artery (SCA), and aberrant left SCA. AA,
ascending aorta; 1, bicarotid trunk; 2, left common carotid artery (CCA); 3, right
CCA; 4, right vertebral artery; 5, right SCA; 6, aberrant left SCA.
Fig. 2 Four-chambered view of computed tomography angiography (A) showing the perimembranous ventricular septal defect (#) and axial section (B) showing the dilated pulmonary arteries causing narrowing of right main bronchus
(dashed arrow). Volume-rendered image of central airways and lungs (C) showing the ostial occlusion of right upper lobe bronchus (arrow) with narrowing
of lower trachea (asterisk) and right main bronchus (dashed arrow) caused by dilated
right pulmonary artery.
Right aortic arch is a rare aortic arch anomaly with aberrant left SCA (type II) being
the most common variation in a right-sided aortic arch followed by mirror image branch
pattern (type I) and isolated left SCA (type III). Associated CHD is invariably seen
with type I and is rarely seen with type II right aortic arch.
Association of bicarotid trunk with aberrant right SCA has been reported previously
with origin of three or four arch vessels, including ectopic origin of vertebral arteries.[2]
[3]
[4] Moreover, associated CHD has been reported in 98.4% of patients with bicarotid trunk
with VSD being the most common followed by pulmonary valve stenosis and atrial septal
defect in a study including pediatric cardiology patients who underwent cardiac catheterization.[5]
Literature search showed no known in human description of association of bicarotid
trunk with aberrant left SCA; however, its occurrence in animals is well documented.[6] Moreover, the association of bicarotid trunk with aberrant left SCA and direct vertebral
artery origin from the right aortic arch, leading to four arch vessels, has not been
reported so far. Our case also highlights the importance of CT in delineation of associated
cardiovascular and tracheobronchial abnormalities. Thorough understanding and description
of arch branching pattern, airway anatomy, and cardiovascular associations are extremely
crucial while planning any endovascular or surgical procedure and intubation. It may
require modification of surgical access or technique with careful observation during
the usage of heart-lung machine or extracorporeal membrane oxygenation (e.g., aortic
cannula may obstruct flow to both the carotid arteries in cases of bicarotid trunk).[5]
[7]
