Cardiac Acclimatization at High Altitude in Two Different Ethnicity Groups

Area of Science:

• Cardiology
• Altitude Medicine
• Physiology

Background:

• High altitude (HA) exposure significantly elevates pulmonary artery pressure (PAP) and resistance.
• The specific effects of HA hypoxia on cardiac function and potential interethnic differences remain poorly understood.
• Research on ethnic variations in cardiac response to HA is limited.

Purpose of the Study:

• To compare cardiac performance in healthy Indian and Kyrgyz subjects during a 3-week exposure to high altitude (4,111m).
• To investigate interethnic differences in cardiac acclimatization to HA.
• To evaluate pulmonary hemodynamics and ventricular functions in response to HA.

Main Methods:

• Noninvasive echocardiography was used to assess cardiac acclimatization in 10 Indian and 20 Kyrgyz subjects.
• Cardiac function was evaluated at baseline, during 3 weeks of HA exposure (days 3, 7, 14, 21), and 3 days after returning to low altitude.
• Measurements included PAP, pulmonary vascular resistance, cardiac output (CO), heart rates (HRs), and ventricular diastolic and systolic functions.

Main Results:

• Both groups showed significant increases in PAP, pulmonary vascular resistance, CO, and HRs at HA.
• Mitral inflow E/A parameters, indicative of left ventricular diastolic function, were impaired in Kyrgyz subjects but not in Indian subjects.
• Right ventricular function remained preserved in both ethnic groups at HA.
• Most cardiac changes reversed upon deinduction, except for a persistent decrease in lateral-septal A' in Indians.

Conclusions:

• Pulmonary hemodynamic responses to HA exposure were similar between Indian and Kyrgyz groups.
• Ethnic variations may influence cardiac functional parameters, particularly left ventricular diastolic function, during HA acclimatization.
• Further research is needed to elucidate the mechanisms behind these ethnic differences in cardiac adaptation to high altitude.