Primary thrombosis of pulmonary artery in a child with tetralogy of Fallot.

A 34-month-old child with tetralogy of Fallot developed an acute, primary thrombosis of the pulmonary trunk. A greatly increased haematocrit was most probably a predisposing factor. An unusual postmortem finding was the large number of extremely dilated myocardial capillaries. In a review of a series of 394 consecutive necropsy cases with many kinds of cardiac anomalies, there was only one case (a 28-year-old man) with occluding thrombus formation in the pulmonary artery. This case also belonged to the Fallot group but a subacute glomerulonephritis seemed to be the major cause of death.