Unilateral absence of a pulmonary artery. Data from cardiopulmonary exercise testing.

A case of congenital, unilateral absence of a left pulmonary artery is described in a patient presenting with exertional dyspnea. Data from cardiopulmonary exercise testing suggest that the mechanism of dyspnea is secondary to a paradoxic elevation of the physiologic dead space to tidal volume ratio (VD/VT) during exercise.