High Altitude in the Heart of Healthy and Sick

Today exposure to high altitudes is relatively common. Thus, basic knowledge is important also for physicians that are not specialised in this topic. Exercise capacity is limited at high altitude, mainly due to hypoxia. Additional factors (circumstances) may aggravate the problem. Still, day trips to altitudes up to 3000–3500 m are relatively safe even in patients with cardiovascular diseases, unless patients are not stable. Unstable patients are not suited for hypoxia exposure although direct evidence is largely lacking. Overnight stay at high altitude increases the risk. Also, patients with moderate to severe pulmonary hypertension, irrespective of the underlying cause, should limit exposure to altitudes of not more than 1500–2000 m. With respect to flying, similar limitations apply. Moreover, circumstances of travel must be taken into account (e.g., limited access to medical help) and sufficient medication (in duplicate at different places) should be taken with the patient. As discussed in the last part of this review, subjects that are susceptible to develop high altitude pulmonary edema should avoid rapid ascent to high altitude, or should be treated prophylactically. To what extent research in these subjects is relevant for pathophysiology of pulmonary hypertension at normoxia needs further investigation.