Three Rare Anomalies of the Large Vessels in an Infant with Tetralogy of Fallot

Isolated left subclavian artery (LSA) from the pulmonary artery (PA) is a very rare vascular anomaly. We report a case of abnormal origin of the LSA from the PA via a very large ductus arteriosus (DA) in association with a rare communication between the left common carotid artery (LCCA) and the LSA in a patient with tetralogy of Fallot. doi: 10.1111/jocs.12770 (J Card Surg 2016;31:461–463)

Isolated left subclavian artery (LSA) from the pulmonary artery (PA) is a very rare vascular anomaly and has been reported in cases of tetralogy of Fallot with a right aortic arch.[1] An anomalous connection of the LSA to the PA via the ductus arteriosus (DA) may cause a pulmonary or subclavian steal phenomenon, whose expression depends on the presence of other vascular sources supplying the left upper limb. This rare congenital vascular malformation is usually associated with chromosomal or genetic abnormalities.

A one‐year‐old female diagnosed with tetralogy of Fallot and trisomy 21 during the newborn period presented with mild cyanosis and a systemic oxygen saturation of 90%. Auscultation revealed a grade 3/6 harsh systolic murmur at the left sternal border. Despite normal development and equal blood pressure levels at both arms, the left upper limb had intermittent cyanosis and coolness, associated with a weak left brachial pulse as compared to the right. Electrocardiogram showed right atrial enlargement and right ventricular (RV) hypertrophy. Echocardiography confirmed the RV hypertrophy and revealed a large malaligned ventricular septal defect (VSD) with a right‐to‐left shunt, severe RV infundibular stenosis and severe stenosis of the pulmonary valve with a pressure gradient of 95 mmHg, and pulmonary annulus z score −1.4. The aortic arch was right‐sided, giving rise to three cephalic branches. At the same time, echocardiography revealed a large vessel with bi‐directional shunting suggesting a patent DA, connected at the proximal end to the main PA and at the distal end to an anomalous vessel, without any connection to the aorta (Fig. [NaN] ).

Computed tomographic imaging confirmed the origin of the LCCA, right common carotid artery (RCCA) and right subclavian artery (RSA) from the right‐sided aortic arch, and the isolation of the LSA from the aortic arch, originating from the DA. The LSA was connected with the main PA via a DA (Fig. [NaN] ). A large aberant communicating vessel was identified between the LCCA and the LSA (Fig. [NaN] ), providing perfusion of the left upper limb with oxygenated blood supplied by the LCCA.

Surgical intervention consisted of closure of the VSD, enlargement of the infundibulum and the pulmonary valve with a transannular patch, and ligature of the DA. Due to the large anastomosis developed between the LCCA and the LSA, anastomosis of the LSA to the aortic arch was not necessary.

The patient was discharged 10 days after the operation with no cyanosis and equal pulses of both upper extremities.

Publication of this case was approved by the institutional review board in the presence of a signed informed consent obtained from the mother.

Right aortic arch is diagnosed in approximately 0.1% of the population. The association of an isolated LSA with a right aortic arch is an uncommon arch anomaly in which the LSA arises from the PA via a patent or nonpatent DA, without any communication with the aorta.[1] , [2] It is frequently associated with intracardiac malformations. Luetmer and Miller reported associated congenital heart defects in 59% of cases of an isolated LSA, tetralogy of Fallot being the most frequent anomaly.[3] , [4] , [5] , [6] Double‐outlet RV and d‐transposition of the great artery have also been reported in association with this rare anomaly.[2] , [3] , [7]

When the LSA is connected to the PA and isolated from the aortic arch, perfusion of the left arm depends largely on the retrograde flow from the vertebral circulation, and on the anterograde flow from the PA.[5] In cases of a patent DA, the connection of the LSA to the main PA via a patent DA leads to the “pulmonary steal phenomenon”, which occurs as a result of the retrograde filling of the pulmonary arterial trunk from LSA via the open DA. Patients with pulmonary steal phenomenon are at risk for pulmonary overcirculation and frequently present with ischemia of the left arm, including pain, weakness, and coolness.[2] These symptoms occurred in our case, who presented with both congenital subclavian, and pulmonary artery steal phenomena.

Several authors have reported differential growth between development of the upper limbs in these cases, while Bricker and colleagues suggested that the differential growing of the upper limbs starts early in the fetal period.[5] , [8] However, McMahon et al. suggested that the differences between the upper limbs are very subtle in most of these cases.[5] , [7] In our case, the distal LSA was filled through the anastomoses between the LCCA and the LSA, and this explains the lack of any difference between upper limbs development.

Computed tomography provides accurate details of the vascular anatomy and helps to plan surgical correction in most of the complex cases.

The optimal management of this rare disease is still controversial as the surgical experience is limited. Since its original description by Dr Anton Ghon in 1908,[9] fewer than 100 cases were reported in the world's literature. The major objectives of surgical treatment focuses on correction of the associated cardiac malformations and ligation of the DA, ensuring anterograde oxygenated blood flow to the left arm. However, patients presenting with cerebral insufficiency, left arm underdevelopment or claudication of the left arm may require reimplantation of the LSA[2] , [3] , [4] , [7] , [10] into the aortic arch, in order to correct the anatomic substrate for the subclavian steal phenomenon.

In our case, ligation of the patent DA eliminated the pulmonary steal phenomenon, while the subclavian steal phenomenon was prevented by the presence of the large comunication between the LCCA and the LSA.

Isolation of the LSA from the PA via the patent DA associated with tetralogy of Fallot is very rare. In the case of an associated large anastomosis between the LCCA and an isolated LSA, which prevents the development of the subclavian steal phenomenon, surgical intervention could be limited to correction of tetralogy of Fallot and ligature of the DA, without any need for reimplantation of the LSA.

Graph: Echocardiographic images demonstrating: A, ventricular septal defect; B, pulmonary stenosis; C, patent ductus arteriosus; D, ductus arteriosus connected at the proximal end to the pulmonary artery; E, ductus arteriosus connected at the distal end to an anomalous vessel, without any connection to the aorta. LA, left atrium; LPA, left pulmonary artery; LV, left ventricle; PS, pulmonary stenosis; RA, right atrium; RPA, right pulmonary artery.

Graph: Computed tomography demonstrating: A, right aortic arch giving rise to three cephalic branches: LCCA, RCCA, and RSA; B, isolated origin of the LSA from PA via a large patent DA and the communication between LCCA and the LSA (small arrows); C, the communication between LCCA and the LSA (small arrows). LPA, left pulmonary artery; RPA, right pulmonary artery.