Authors: Mouna Kanaan , Diana Alasmar , Anas M. Alrefai , Mohammad Nasser Khattab , Mohammad Younes

Abstract

Background: Co-occurrence of dextro-transposition of the great arteries (D-TGA) and severe hypertrophic cardiomyopathy (HCM) is an exceptionally rare and hemodynamically precarious scenario. While transient, reversible HCM is well-documented in neonates of diabetic mothers, idiopathic biventricular HCM presenting late in infancy introduces unique physiological barriers.
Case Presentation: We present the case of a 4-month-old, non-diabetic infant diagnosed with parallel circulation D-TGA, complicated by massive biventricular hypertrophy, a large ventricular septal defect, and flow-related pulmonary hypertension.
Discussion: The contemporaneous presentation of these pathologies creates a vicious hemodynamic cycle: the excessive volume
and pressure loading from unrestrictive shunts collide with severe intrinsic biventricular hypertrophy, culminating in profound diastolic dysfunction and severely restricted inter-circulatory mixing. This case underscores that, unlike transient neonatal HCM, late-presenting non-diabetic hypertrophy combined with high-volume pulmonary overcirculation renders traditional bridging and corrective therapies physiologically intolerable.
Conclusion: We detail the profound surgical limitations in this subset of patients - specifically the theoretical contraindications for pulmonary artery banding, the Arterial Switch Operation, and atrial switch procedures. We highlight why formal surgical atrial septectomy, with or without patent ductus arteriosus ligation, is proposed as a potential salvage pathway to navigate such profound physiological fragility when advanced percutaneous interventions are unavailable.

Keywords: D-transposition of the great arteries, Congenital anomalies, Hypertrophic cardiomyopathy.