A natural systemic to pulmonary artery shunt.

Isolation of the left subclavian artery is a rare anomaly associated with right aortic arch. We report a case in which this subclavian artery was supplying the pulmonary circulation in a patient with tetralogy of Fallot (TOF) which effectively acted as a natural systemic to pulmonary artery shunt. The patient had good room air saturation and no features of vertebrobasilar insufficiency or left upper limb ischemia. She underwent a total correction of TOF and ligation of the aberrant left subclavian artery.