Complex Cyanotic Congenital Heart Disease in Pregnancy: Survival With Unrepaired Pulmonary Atresia and Ventricular Septal Defect - A Case Report.

Pulmonary atresia with ventricular septal defect and systemic-to-pulmonary collateral supply is a severe conotruncal malformation characterized by complete right ventricular outflow tract obstruction, a large ventricular septal defect, and absence of a main pulmonary artery. Without surgical repair, survival into adulthood is rare and depends on the adequacy of collateral pulmonary blood flow. Pregnancy in women with unrepaired cyanotic congenital heart disease carries extreme maternal and fetal risk and is classified as modified World Health Organization class IV when resting oxygen saturation is below 85%. We report a 22-year-old woman at 32 weeks' gestation who presented with progressive dyspnoea, severe hypoxaemia (oxygen saturation 74%), and heart failure. Echocardiography demonstrated a large perimembranous ventricular septal defect and pulmonary atresia. Cardiac computed tomography confirmed an overriding aorta, non-confluent pulmonary arteries arising from the descending thoracic aorta and aortic arch, and absence of a main pulmonary trunk, establishing the diagnosis of pulmonary atresia with ventricular septal defect and systemic-to-pulmonary collateral supply. She underwent caesarean delivery for maternal decompensation, complicated by postpartum haemorrhage requiring hysterectomy. Ten days postpartum, she developed an acute ischaemic stroke. Telemetry excluded atrial fibrillation, and imaging showed no intracardiac thrombus. She improved with antiplatelet therapy and supportive care and remained clinically stable at six-month follow-up. This case highlights the rare survival of unrepaired complex cyanotic congenital heart disease into adulthood, the extreme risks of pregnancy in this setting, and the need for preconception counselling, multidisciplinary management, and vigilant postpartum thromboembolic risk assessment, particularly in resource-limited settings.