Thoracic aortic dissection that wasn't: CT demonstration of probable paradoxical embolus secondary to unsuspected pulmonary embolus.

A patient presented with chest pain, cyanosis and acute ischaemia of the left arm. Aortic dissection was considered to be the likely diagnosis. CT demonstrated multiple large pulmonary emboli and a serpiginous thrombus occluding the origin of the left subclavian artery. Venous thrombosis was proven. The sudden onset of cyanosis followed immediately by a systemic arterial embolus with morphology typical of a venous source was very likely the result of transforaminal shunting induced by massive pulmonary emboli. Post-mortem studies have demonstrated a high incidence of asymptomatic patent foramen ovale in normal individuals. Using contrast echocardiography techniques, any physiological or pathological rise in right heart pressure increases the likelihood of right to left transforaminal shunting of blood or embolic material.