Congenital Heart Disease

Congenital heart disease (CHD) is an anatomic problem, but its urgency is determined by physiology: where blood goes, whether it reaches the lungs or systemic circulation, and whether enough oxygenated blood reaches the tissues. CHD affects roughly 1 in 100 live births; approximately one quarter of affected infants have critical disease requiring surgery or catheter intervention during the first year. The transition after birth exposes the defect. Pulmonary vascular resistance falls, pulmonary blood flow changes, and the ductus arteriosus normally constricts. A lesion that was temporarily supported by fetal circulation may therefore cause sudden cyanosis, heart failure, or shock within hours or days. Ductal-dependent lesions are especially time-sensitive because pulmonary blood flow, systemic blood flow, or mixing between the two circulations depends on a patent ductus. For clinical reasoning, begin with three questions: Is blood moving excessively to the lungs, bypassing the lungs, or failing to reach the systemic circulation? Is the patient compensating, or is tissue perfusion falling? Could the ductus be the only remaining route for adequate circulation? These questions organise assessment, screening, treatment, and escalation more reliably...