Paradoxical renal embolism in a patient with congenital cardiac malformation.
Paradoxical embolism is a rare phenomenon in which thrombotic material passes through a right–left shunt to the systemic circulation. This most often occurs across a patent foramen ovale.1 Usual sites of embolism are the brain and the extremities, paradoxical embolism into the kidney is much less common.2

A 35-year-old man was admitted with sudden new-onset pain in his right flank. He had been born with a complex cardiac malformation consisting of double outlet right ventricle with malposition of the great arteries, straddling of the tricuspid valve and large atrial and ventricular septal defects. During the newborn period, pulmonary artery banding was conducted. Three years later corrective surgery was attempted; however, de-banding of the pulmonary artery resulted in pulmonary congestion. Thus, pulmonary artery banding was restored and a palliative Mustard procedure was performed to achieve an increase in systemic arterial oxygen saturation by changing streaming and reducing the amount of venous blood that reaches the aorta (Figure 1). After this surgery, the patient developed relatively normal with only minor physical limitations. At the age of 33 years, cardiac function progressively deteriorated resulting in repetitive cardiac decompensation. Two months before the current admission, the patient presented with numbness and tingling of his left arm and leg, which was interpreted as a transient ischemic attack. Thromboembolism due to intermittent atrial fibrillation was assumed to be the most likely source, because the patient reported palpitations, and atrial tachycardia is a common late arrhythmia after the Mustard procedure.3 



Figure 1. 
( A ) Computed tomography demonstrating the enlarged right ventricle (RV) as well as …