• Roman Brenner, Lorenza Pratali, Stefano F Rimoldi, Carla Ximena Murillo Jauregui, Rodrigo Soria, Emrush Rexhaj, Carlos Salinas Salmón, Mercedes Villena, Catherine Romero, Claudio Sartori, Yves Allemann, and Urs Scherrer.
• Chest. 2015 Apr 1;147(4):1072-9.

BackgroundThere is considerable interindividual variability in pulmonary artery pressure among high-altitude (HA) dwellers, but the underlying mechanism is not known. At low altitude, a patent foramen ovale (PFO) is present in about 25% of the general population. Its prevalence is increased in clinical conditions associated with pulmonary hypertension and arterial hypoxemia, and it is thought to aggravate these problems.MethodsWe searched for a PFO (transesophageal echocardiography) in healthy HA dwellers (n = 22) and patients with chronic mountain sickness (n = 35) at 3,600 m above sea level and studied its effects (transthoracic echocardiography) on right ventricular (RV) function, pulmonary artery pressure, and vascular resistance at rest and during mild exercise (50 W), an intervention designed to further increase pulmonary artery pressure.ResultsThe prevalence of PFO (32%) was similar to that reported in low-altitude populations and was not different in participants with and without chronic mountain sickness. Its presence was associated with RV enlargement at rest and an exaggerated increase in right-ventricular-to-right-atrial pressure gradient (25 ± 7 mm Hg vs 15 ± 9 mm Hg, P < .001) and a blunted increase in fractional area change of the right ventricle (3% [-1%, 5%] vs 7% [3%, 16%], P = .008) during mild exercise.ConclusionsThese findings show, we believe for the first time, that although the prevalence of PFO is not increased in HA dwellers, its presence appears to facilitate pulmonary vasoconstriction and RV dysfunction during a mild physical effort frequently associated with daily activity.Trial RegistryClinicalTrials.gov; No.: NCT01182792; URL: www.clinicaltrials.gov.

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