Most patients after an MI and other cardiac conditions can return to high altitudes, including air travel, after a few weeks, according to information presented at the American College of Cardiology Scientific Session.
“Altitude does require more work from the [CV] and respiratory systems,” John P. Higgins, MD, MPhil, MBA, FACC, FACP, FAHA, director of exercise physiology at Memorial Herman Sports Medicine Institute in Houston, chief of cardiology at Lyndon B. Johnson General Hospital in Houston and associate professor of cardiovascular medicine at the University of Texas Medical School in Houston, said in his presentation. “People with mild to moderate stable [CVD] can go with the right precautions and preparation to altitude. However, those that have [instability], high risk or a recent procedure should delay travel and be guided by their provider.”
Higgins said bodies work most efficiently at sea level, where the barometric pressure is around 760 mm Hg. At sea level, the partial pressure of inspired oxygen is 149 mm Hg and in-arterial saturation in blood is 98%. In higher altitudes, the partial pressure of the inspired oxygen decreases. At 8,000 feet, or where airplanes are pressurized, the barometric pressure is an estimated 564 mm Hg, the partial pressure of inspired oxygen is 108 mm Hg and in-arterial blood saturation is 60%.
“A healthy individual should have a saturation of 90% or more and be able to handle that without any problems,” Higgins said.
A short-term effect of going to a higher altitude is hypobaric hypoxia, where the body increases its minute ventilation and tidal volume, which causes hypoxic pulmonary vasoconstriction. The body’s cardiac output is increased to compensate for it, Higgins said.
Higgins reviewed the recommended amount of time before patients can return to higher altitudes and air travel. Patients with CAD and prior MI who are stable experience angina symptoms at lower workloads. Those who had non–STEMI or STEMI should wait 2 weeks before flying or going to a location of high altitude, but if they had a complicated case of MI, 6 weeks is recommended. Patients with a recent diagnosis of ACS who were not revascularized are recommended to have a maximum stress test prior to air travel, but if they are revascularized with PCI and have no complications, they can wait a couple of days. Patients who recently underwent CABG should wait 10 days for gas to be reabsorbed, he said.
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