Systemic to pulmonary artery shunting.

Two cases showing systemic to pulmonary artery shunting, during the venous phase of bronchial arteriography are presented. In the first patient with chronic bronchiectasis, the shunting is believed to be due to newly formed vessels in the granulomatous tissue. At pulmonary angiography, the increased pressure in the pulmonary arteries simulated an angiographic defect due to dilution of the contrast by retrograde opacification from a left to right shunt. In a second patient with proven pulmonary embolism a true defect was present at pulmonary angiography. Systemic to pulmonary artery shunting is believed to develop secondary to hypoxia.