As more people travel to higher altitudes for recreation and adventure, high altitude and lower oxygen availability need to be considered. For most people this causes few problems, but for those with lung or heart disease, altitude can have a negative effect on health. Acute exposure to high altitude can affect the cardiovascular system by decreasing oxygen in the blood (acute hypoxia). It also increases demand on the heart, adrenaline release and pulmonary artery pressures.
Significant changes in atmospheric pressure, oxygen pressure, humidity and temperature typically begin at about 2500 m (8200 ft). How this affects patients depends on many factors, including existing conditions (such as a PFO, which is a hole between the two chambers of the heart), duration of acclimatization, exercise intensity, age and, of course, the genes you were born with.
High-altitude Pulmonary Edema
Acclimation is the process of adapting to changes in a person's environment. With altitude, that means ascending slowly, giving the body time to adjust. High-altitude pulmonary edema affects unacclimated people with a genetic predisposition, usually within 3-4 days of arriving at altitude. This causes fluid to build up in the lungs and makes it difficult to breathe.
Slow ascent serves as a preventive measure. (For ascent greater than 3050m [10,000 ft], ascent should be 305m [1000 ft] daily with a rest every 1000m [3300 ft].) If pulmonary edema is suspected, immediate descent and supplemental oxygen is the treatment of choice. Medication can also be used to both prevent and treat high altitude pulmonary edema.
General Recommendations for Traveling to Higher Altitudes
- Stay hydrated.
- Ascend slowly and take breaks.
- Limit activity to a lower rate than at sea level.
- Raise sleeping altitude gradually.
- Stay conditioned and in shape - Continued moderate physical conditioning at sea level is encouraged before exercise at altitude.
- Alcohol consumption should be minimized, and hydration should be maintained.
- Your doctor may consider exercise testing prior to travel.
Recommendations for Those with Heart Disease
- Patients with unstable cardiac disease (unstable angina, uncontrolled ventricular arrhythmias, decompensated heart failure) should not exercise at high altitude. It may be good to postpone a trip until the heart conditions are stabilized or avoid it altogether.
- Patients with severe cardiac diseases (including severe angina, heart failure, or valve disease) should not visit high altitudes.
- Most patients should avoid high altitude for two weeks after an acute coronary event i.e. heart attack, stent or bypass surgery.
- Patients with stable heart disease should limit physical activity for the first few days after ascending to a high altitude. Be on the lookout for symptoms and stop activity if they occur.
- Patients with prior high altitude pulmonary edema and known intracardiac shunts (holes in the heart) should be advised to avoid travel to high altitude.
- Pacemaker patients can usually safely travel to high altitude.
- Always check with your doctor before any travel to high altitude.