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Total anomalous pulmonary venous return typically presents in infancy with congestive heart failure. In contrast, partial anomalous pulmonary venous connection (PAPVC) may be asymptomatic and found incidentally on chest roentgenogram or during evaluation of a murmur, or even be an incidental finding at autopsy; PAPVC is often associated with atrial septal defect and occasionally with complex cardiac defects. Isolated PAPVC in association with intact atrial septum remains unusual and may join the venous circulation at various locations. Drainage of the left upper lobe via a vertical vein to the brachiocephalic vein, as in our patient, is the most common pattern. The clinical significance of PAPVC relates to the magnitude of the left-to-right shunt. The number of anomalous pulmonary veins, the presence and degree of pulmonary venous obstruction, and the presence of concomitant lung disease affect the risk for the development of pulmonary hypertension. It has generally been assumed that if less than 50 percent of the pulmonary circuit drains into the right side of the heart, pulmonary hypertension would not ensue. Recent reports by Saalouke et al and Babb et al have challenged this notion and suggest that pulmonary hypertension can develop even with small shunts due to PAPVC, although mechanisms to explain this are speculative. We are unable to estimate the magnitude of left-to-right shunt in our patient since at the time of PAPVC discovery it was not possible to obtain a true mixed venous oxygen saturation antegrade to the site of the shunt. It is not fully satisfying to attribute our patients pulmonary hypertension and right ventricular hypertrophy to his asthma. It is at least possible that his life-long shunt played a role. Recognition of the significance of a malpositioned central venous catheter therefore contributed to our synthesis of this patients findings.