Discussion

In cases of an isolated left brachiocephalic artery with bilateral patent ductus arteriosus, increased pulmonary blood flow and pronounced cerebral perfusion steal can occur. We successfully managed a patient with transcatheter ductal occlusion.

The embryogenesis of an isolated left brachiocephalic artery was originally explained by Edwards’ hypothetical model of a double aortic arch.^{Reference Crawford3,Reference Fong and Venables4} If an interruption of the left aortic arch occurs between the ascending aorta and the left carotid artery during embryonic vascular development, an isolated left brachiocephalic artery results, which is then connected to the main pulmonary artery via the left ductus arteriosus. Perfusion of the left brachiocephalic artery is maintained by retrograde blood flow from the left common carotid and left vertebral arteries through the circle of Willis. Some cases remain asymptomatic and unrecognised if both ductus arteriosus spontaneously close. However, when the left ductus arteriosus remains patent, the resolution of physiological pulmonary hypertension increases retrograde flow through the circle of Willis, thereby worsening cerebral steal and pulmonary overcirculation.

A previous review of isolated left brachiocephalic artery cases^{Reference Rad and Pouraliakbar5} showed that among patients with a patent left ductus arteriosus, 76.4% had concomitant CHD and 94.1% presented with symptoms of high pulmonary blood flow. Cerebral atrophy of the left hemisphere has been reported in 25% of cases with bilateral patent ductus arteriosus, caused by pulmonary arterial steal of cerebral blood flow. In the present case, no associated cardiac anomalies, extracardiac malformations, or dysmorphic features were present, and the thymus was normal. Genetic testing was not performed.

Percutaneous closure of the bilateral patent ductus arteriosus was successfully performed in a patient with isolated left brachiocephalic artery—the first reported percutaneous intervention for this condition, to our knowledge. Reports of percutaneous intervention for patent ductus arteriosus in isolated left subclavian artery exist;^{Reference Alhuzaimi, Aldawsari and Al-Ahmadi6,Reference Koneti, Qureshi and Sivakumar7} however, isolated left brachiocephalic artery is associated with more pronounced brain steal due to retrograde flow in the left internal carotid artery, warranting intervention. Cerebral perfusion scintigraphy revealed decreased perfusion in the left hemisphere. Previous reports have described left-dominant cerebral atrophy between 3 and 13 months of age in patients with left patent ductus arteriosus and an isolated left brachiocephalic artery.^{Reference Hayabuchi, Inoue and Sakata1,Reference Reeves, Colen and Sheridan2,Reference Binka, Sun and Gailloud8} Although surgical intervention was also considered, the absence of additional cardiac anomalies, the distance between the left brachiocephalic artery and the right aorta, and the uncertainty regarding the extent of ductal tissue involving the left brachiocephalic artery led us to select the percutaneous approach, which was deemed less invasive.

In the present case, preintervention cranial CT revealed no cerebral atrophy, underscoring the need to individualise the optimal timing of the intervention. A previous report suggested using diastolic retrograde flow in the left intracranial internal carotid artery as an indicator for intervention,^{Reference Parsons, Nuttall and Jones9} but accurately assessing its haemodynamic significance is challenging. Brain perfusion scintigraphy before and after surgery demonstrated improvement in the cerebral perfusion pattern (Figure 2c,d). In particular, in cases with persistent bilateral patent ductus arteriosus, cerebral blood flow steal tends to be more pronounced, and reports of cerebral atrophy as early as 3 months of age support considering earlier intervention in such patients.