# Physiological responses of children with surgically corrected congenital heart disease during high-altitude trekking: an exploratory observational study

## TL;DR

Children with surgically corrected heart defects can safely trek at high altitudes, showing good physiological adaptation.

## Contribution

This study explores physiological responses of children with CHD during high-altitude trekking, offering new insights into their cardiovascular adaptation.

## Key findings

- Oxygen saturation declined similarly in children with CHD and adults during ascent.
- Children with CHD showed increased heart rate but stable blood pressure at high altitudes.
- No evidence of maladaptation or altitude-related illness was observed in CHD participants.

## Abstract

Children with surgically corrected congenital heart disease (CHD) are often perceived as fragile and discouraged from engaging in physical activity, despite evidence that structured exercise improves functional capacity and quality of life. However, data on their physiological responses to extreme environments, such as high-altitude exposure, remain limited.

We conducted an exploratory observational study during an Annapurna Base Camp trek (maximum altitude 4,150 m) in February 2024. Children with surgically corrected congenital heart disease and accompanying healthy adults participated in the expedition. Oxygen saturation (SpO2), heart rate (HR), and blood pressure (SBP and DBP) were recorded daily at sequential altitudes, and adverse events were monitored.

From 1,350 m to 4,150 m, SpO2 showed a similar pattern of decline in children (−9.8%) and adults (−8.1%). CHD participants showed a pronounced chronotropic response (+17.8 bpm) with modest declines in both SBP (−9.0 mmHg) and DBP (−5.5 mmHg), while adults showed minimal change. These findings suggest effective cardiovascular adjustment under hypobaric hypoxia and with no evidence of maladaptation or altitude-related illness.

Children with surgically corrected CHD showed preserved oxygenation and well-tolerated hemodynamic responses during high-altitude trekking, underscoring their capacity for physiological adaptation when adequately prepared and supervised. The study highlights the feasibility and safety of structured physical challenges for this population and provides preliminary insight into designing exercise programs that promote confidence and participation.