Pulmonary haemodynamic response to exercise in highlanders versus lowlanders

Area of Science:

• Cardiovascular Physiology
• Altitude Medicine
• Exercise Physiology

Background:

• High-altitude environments present unique physiological challenges.
• Understanding pulmonary haemodynamic responses to exercise is crucial for acclimatization.
• Central Asian populations offer a distinct model for studying altitude adaptation.

Purpose of the Study:

• To investigate pulmonary haemodynamic responses to exercise in Central Asian highlanders versus lowlanders.
• To compare cardiac function metrics, including TRPG, cardiac index, and TAPSE, during exercise.
• To determine the impact of chronic hypoxia on the pressure-flow relationship in highlanders.

Main Methods:

• Cross-sectional study comparing highlanders (>2500m) and lowlanders (<800m).
• Echocardiography assessed TRPG, cardiac index, and TAPSE.
• Pulse oximetry measured SpO2 during submaximal stepwise cycle exercise.
• 52 highlanders and 22 lowlanders participated.

Main Results:

• Highlanders had lower resting SpO2 but similar exercise-induced changes.
• Significantly elevated TRPG and a steeper exercise-induced increase in TRPG were observed in highlanders.
• A steeper pressure-flow ratio (ΔTRPG/Δcardiac index) was found in highlanders compared to lowlanders.
• Right ventricular-arterial coupling (TAPSE/TRPG) was lower in highlanders at rest.

Conclusions:

• Chronic hypoxia exposure in Central Asian highlanders leads to higher pulmonary artery pressure.
• Highlanders demonstrate a steeper pulmonary pressure-flow relationship during exercise.
• These findings highlight altered pulmonary vascular adaptation to chronic hypoxia and exercise.