Atresia of the pulmonary veins of the left lung and the right upper lo
be with moderate pulmonary hypertension was diagnosed in a 20 year old
man presenting with exertional dyspnoea and haemoptysis. After left p
neumonectomy gas exchange appeared to have improved. This was shown by
improved arterial oxygen pressures during all steps of exercise in a
cycle ergometer test in comparison with values obtained before surgery
. This improvement could be entirely attributed to a decrease in physi
ological dead space ventilation.