Pulmonary embolism in a patient of tetralogy of Fallot: a diagnostic challenge

A 46-year-old male patient with tetralogy of Fallot presented to the emergency department with progressive dyspnea for 3 days. The dyspnea was refractory to treatment for tet spells. Pulmonary embolism (PE) was subsequently diagnosed by computed tomography, and the patient was successfully treated with heparinization. Chronic hypoxemia-induced secondary polycythemia and the consequent increase in blood hyperviscosity predisposed this patient to PE. This case reminds us of the similarity in clinical presentation between PE and tet spells.