Tunnel Aorto‐Pulmonary Window in a Child With Tetralogy of Fallot: Natural Central Shunt

To the Editor, A 4-year-old child presented to the outpatient department with complaints of chronic dry cough and low-grade fever of 1-month duration. There was a history of difficulty in breathing, especially during exertion. There was no history of cyanosis, chest pain, or wheeze. Past history of recurrent respiratory tract infections was present, managed at a local hospital. His vitals were stable with a SpO2 of 92% on room air. On chest auscultation, there was the presence of bilateral basal crepitations. Transthoracic echocardiography suggested tetralogy of Fallot (TOF) along with an aorto-pulmonary window (APW) with left-to-right shunting. Computed tomography pulmonary angiography (CTPA) done for further evaluation showed a subaortic ventricular septal defect (VSD) with aortic-overriding (black star, Figure 1A) and infundibular pulmonary stenosis, confirming the echocardiographic finding of TOF. There was tunnel-shaped communication between the distal ascending aorta and the proximal right pulmonary artery (dashed line, Figure 1B–E), suggestive of tunnel APW, mimicking a central shunt. Separate semilunar valves were seen, and the pulmonary valve was bicuspid. The tunnel measured 2 cm in length with a diameter of 8 mm, without evidence of any significant stenosis or thrombosis. Ancillary finding included double superior vena cavae (Figure 1C). Aortopulmonary window is a rare congenital cardiac anomaly, characterized by an intrapericardial communication between the ascending aorta and the pulmonary trunk in the presence of two separate semilunar valves. Most of the cases of APW described in literature are window-like defects [1]. Very rarely can APW have a tunnel-like morphology, such as in this case, with few reported cases [2, 3]. To the best of our knowledge, no case of distal tunnel APW in a child with TOF has been described previously. Saurabh Deshpande: conceptualization, writing – original draft; writing – review and editing. Pratyaksha Rana: conceptualization, writing – original draft. Megha M. Sheth: writing – review and editing, supervision. Hit Jivani: writing – review and editing. T. M. Harishkar: writing – original draft. Dinesh Patel: supervision, resources. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.