ST segment depression after Norwood/systemic-pulmonary artery shunt

A three-month-old girl with double inlet left ventricle(S;D;D), hypoplastic outlet ventricle, restrictive bulboventricular foramen, d-transposition of great arteriesand interrupted aortic archunderwent Norwood stage 1 operation, systemic to pulmonary artery (PA) shunt and atrial septectomy, and developed ectopic atrial tachycardiathat responded to digoxintherapy. She developed fussiness lasting two hours, not associated with cyanosis, and not relieved by feeding. Her pulse oximetrywas 88% while breathing room air, and she had no differential blood pressure gradient. Apart from single second heart soundand a grade IV/VI ejection systolic murmur, the examination was normal. Her electrocardiogram and echocardiogram were unchanged. A Holter monitorrevealed ST segmentdepression and T waveinversion upon increasing the heart rate beyond 140 beats/minute (Figs. 1 and 2). A cardiac catheterization showed patent systemic to PA shunt, patent native aorta, and no evidence of coarctation of aorta. After undergoing the second stage operation, her diastolicrunoff and symptoms of fussiness disappeared and a surveillance Holter monitorshowed better-looking ST segmentsand T waveseven at higher heart rates (Figs. 3 and 4). Three months later, the patient is doing well and is awaiting Fontan completion. Figure 1 Absence of ST segmentdepression with a heart rate <140 beats/minute in a patient with Norwood/systemic to pulmonary artery shunt with diastolicrunoff flow. Figure 2 ST segmentdepression and T waveinversion with a heart rate >140 beats/minute in a patient with Norwood/systemic to pulmonary artery shunt with diastolicrunoff flow. Figure 3 Absence of ST depression with a heart rate <140 beats/minute after stage II palliation with no diastolicrunoff flow. Figure 4 Absence of ST depression with a heart rate >140 beats/minute after stage II palliation with no diastolicrunoff flow. Despite many advances in the field of pediatric cardiology, the interstage mortality rate remains high [1]. The use of the systemic to PA shunt in the Norwood operation has been complicated by wide pulse pressure, diastolicrunoff flow [2,3], uneven distribution of pulmonary blood flow [4], and increased early mortality [5]. Providers need to keep a high index of suspicion for the adverse effects of the diastolicrunoff that accompanies the presence of systemic to PA shunts.