Why High-Altitude Trips Affect Heart Functioning

Whenever a person ventures into hilly, high-altitude regions, their body starts developing inefficient physiological responses, mainly marked by an increase in breathing and heart rate to as much as double, even at the time of resting.

The reason for this, as already established, is the reduction in the amount of blood the heart pumps with each beat. Scientists have known this problem for more than a century, but there has been no fixed answer as to why the heart’s ability to pump blood declines at high-altitudes.

From modern-day tourists to those involved in the first-ever summit to the Mount Everest, every traveler has been looking for an answer to this mystery.

This is why a group of researchers from Cardiff Metropolitan University, United Kingdom, University of British Columbia Okanagan, Canada, and the Loma Linda University School of Medicine in the United States conducted a two-week long observational study at a remote research facility called The Barcroft Laboratory on White Mountain, California.

They called a small group of participants and took a close look at how the heart and pulmonary blood vessels responded to hypoxic conditions or environments with less oxygen commonly found in high-altitude areas. The whole process was completely invasive as the researcher used a technique called echocardiography where ultrasound waves are used to investigate the action of the heart.

The findings of the work revealed critical insights into the functioning of the heart. Essentially, the researchers found at high altitudes, going beyond 3,000 meters, the reduced amount of oxygen present in the air decreases the volume of blood circulating in the body and increases blood pressure in the lungs. As a result, these two factors jointly contribute to the reduction in the amount of blood the heart is able to pump.

The work also established neither of the two issues compromised the participants’ ability to perform extensive exercises. The researchers believe this as well as other related studies could make high-altitude trips safer for travelers, and performance of participants in high-altitude sporting events.

That said, it is worth noting the findings revealed in this study are just preliminary and broader work would be required to build on the data collected. This particular study was based on a few number of individuals of European descent.

"Currently, a number of the research team are ready to depart for an expedition that will focus on high altitude natives who live and work in the industrial mines of the Andean mountains. Unfortunately, a third of these individuals experience long-term ill health due to their residence at high altitude, a condition termed 'Chronic Mountain Sickness',” Michael Stembridge, the chief investigator on the project said in a statement. “We hope to apply the findings of this work to help improve the health and well-being of these populations by furthering our understanding of the condition and exploring therapeutic targets".

The study was published May 28 in the Journal of Physiology.