Most of the people who climb Mount Everest are adventure seekers who are thrilled with the challenge of trekking the world's tallest mountain. A group of researchers has decided to join an expedition to Mount Everest for scientific reasons that could potentially benefit individuals with certain medical conditions.
For the study published in the European Heart Journal on Aug. 26, Italian researchers joined an expedition of 47 volunteers who travelled to the south base camp of Mount Everest that sits at an altitude of 5,400 meters, where they stayed for 12 days.
The volunteers were fitted with a device that monitored and measured their blood pressure round the clock as they climbed to the base camp and were randomly assigned to receive either 80 milligrams of telmisartan, a blood-pressure lowering drug that works by blocking the effects of a peptide called angiotensin II that causes the narrowing of blood vessels, or placebo. The researchers also collected blood samples from the volunteers.
Study researcher Gianfranco Parati, from the Department of Health Sciences of the University of Milano-Bicocca in Milan, Italy, and colleagues found that exposure to very high altitude increases ambulatory systolic blood pressure by 14 mmHg and elevates ambulatory diastolic blood pressure by 10 mmHg on average over a 24-hour period.
The researchers said that the increase in blood pressure can be attributed to a number of factors, most important of which is the deprivation of oxygen that causes the heart to work harder and the peripheral blood vessels to constrict.
They also observed that while the angiotensin receptor blocker (ARB) telmisartan significantly lowered the ambulatory blood pressure at sea level and at an altitude of 3,400 meters, the blood pressure lowering drug no longer works when the volunteers reached the altitude of 5,400 meters.
"Ambulatory blood pressure increases progressively with increasing altitude, remaining elevated after 3 weeks," the researchers wrote. "An angiotensin receptor blockade maintains blood pressure-lowering efficacy at 3400 m but not at 5400 m."
Parati and colleagues said that the findings of their study have implications on individuals with medical conditions that result in oxygen deprivation such as chronic heart failure, obstructive sleep apnea and severe obesity that together affects over 600 million people globally.
"Our findings will also enable us to take appropriate action to warn cardiovascular patients of the need for caution whenever they are going to be exposed to high altitudes for leisure or work," Parati said.
