Exaggerated pulmonary hypertension and right ventricular dysfunction in high-altitude dwellers with patent foramen ovale.
BACKGROUND
There 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.


METHODS
We 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.


RESULTS
The 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.


CONCLUSIONS
These 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.


BACKGROUND
ClinicalTrials.gov; No.: NCT01182792; URL: www.clinicaltrials.gov.
Department of Cardiology and Clinical Research, University Hospital Bern, Bern, Switzerland.
Roman
R
Brenner
Institute of Clinical Physiology, Pisa, Italy.
Lorenza
L
Pratali
Department of Cardiology and Clinical Research, University Hospital Bern, Bern, Switzerland.
Stefano F
SF
Rimoldi
Instituto Boliviano de Biologia de Altura, La Paz, Bolivia.
Carla Ximena
CX
Murillo Jauregui
Department of Cardiology and Clinical Research, University Hospital Bern, Bern, Switzerland.
Rodrigo
R
Soria
Department of Cardiology and Clinical Research, University Hospital Bern, Bern, Switzerland.
Emrush
E
Rexhaj
Instituto Boliviano de Biologia de Altura, La Paz, Bolivia.
Carlos
C
Salinas Salmón
Instituto Boliviano de Biologia de Altura, La Paz, Bolivia.
Mercedes
M
Villena
Instituto Boliviano de Biologia de Altura, La Paz, Bolivia.
Catherine
C
Romero
Department of Cardiology and Clinical Research, University Hospital Bern, Bern, Switzerland.
Claudio
C
Sartori
Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Yves
Y
Allemann
Department of Cardiology and Clinical Research, University Hospital Bern, Bern, Switzerland; Facultad de Ciencias, Departamento de Biología, Universidad de Tarapacá, Arica, Chile. Electronic address: urs.scherrer2@insel.ch.
Urs
U
Scherrer
D000531:Altitude; D017548:Echocardiography, Transesophageal; D054092:Foramen Ovale, Patent / Q000150:complications* / Q000175:diagnosis; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D013557:Switzerland / Q000453:epidemiology; D014655:Vascular Resistance; D018497:Ventricular Dysfunction, Right / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D016278:Ventricular Function, Right / Q000502:physiology*