To the Editor: In their case-control study, Dr Allemann and colleagues1 identified an association between patent foramen ovale (PFO) and susceptibility to high-altitude pulmonary edema (HAPE) in mountaineers. In HAPE-susceptible participants, they observed low arterial oxygen saturation that preceded the onset of clinical HAPE. Their study suggests that intracardiac right-to-left shunting through a PFO is partly responsible for this hypoxemia. We believe that subclinical pulmonary edema may also contribute to the early hypoxemia observed in this group and suggest a means of evaluating this in future studies.
Fagenholz PJ, Harris NS. High-Altitude Pulmonary Edema and Patent Foramen Ovale. JAMA. 2007;297(13):1432-1433. doi:10.1001/jama.297.13.1432-a