title: High altitude-induced borderline pulmonary hypertension impaired cardiorespiratory fitness in healthy young men.
abstract: OBJECTIVE
  High altitude exposure has been suggested to cause borderline elevation of pulmonary artery pressure (PAP) in quite a few healthy individuals. This cohort study was to investigate the impact of altitude induced borderline pulmonary hypertension (PH) on cardiorespiratory fitness in healthy subjects.
  
  
  METHODS
  299 healthy Chinese young men with normal PAP were consecutively studied between July 2011 and September 2013. Among these subjects 114 kept living at low altitude (450m), 91 ascended to high altitude (3700m) from low altitude within 24h (acute exposure), and 94 resided at 3700m for more than 1year (chronic exposure). Mean PAP and cardiac function were examined by echocardiography, and cardiorespiratory fitness was determined by predicted work capacity at a heart rate of 170beats per minute (PWC170).
  
  
  RESULTS
  Mean PAP remained within normal range (<20mmHg) in 113 of 114 participants (99%) at low altitude. In contrast, the incidence of borderline PH (mPAP between 20 and 25mmHg) was 29% and 37% for respective acute and chronic exposures. Compared to the subjects with normal mPAP within each of the exposure groups, the subjects with borderline PH had increased right ventricular Tei index (RV-Tei), which correlated with the decline of PWC170 (acute exposure: r=-0.296, p=0.004; chronic exposure: r=-0.247, p=0.016). However, these changes were relatively milder than those with confirmed PH (mPAP>25mmHg).
  
  
  CONCLUSIONS
  Borderline PH compromised cardiorespiratory fitness in healthy young men. The decline of cardiorespiratory fitness was related at least in part with the impaired right ventricular function, which was correlated with the elevated mPAP.
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Te
authors.initials: T
authors.lastname: Yang
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Li
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Qin
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Shuangfei
authors.initials: S
authors.lastname: Li
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Jihang
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Shiyong
authors.initials: S
authors.lastname: Yu
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China. Electronic address: xiaojingwu1992@163.com.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Wu
authors.affiliation: Cardiovascular Department of Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China. Electronic address: huanglan260@126.com.
authors.forename: Lan
authors.initials: L
authors.lastname: Huang
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000175:diagnosis* / Q000503:physiopathology; D001794:Blood Pressure / Q000502:physiology*; D015331:Cohort Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D010809:Physical Fitness / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology*; D055815:Young Adult
keywords: Cardiorespiratory fitness; Cohort study; High altitude; Pulmonary hypertension