Changes in 24 h ambulatory blood pressure and effects of angiotensin II receptor blockade during acute and prolonged high-altitude exposure: a randomized clinical trial

Abstract

Ambulatory blood pressure increases progressively with increasing altitude, remaining elevated after 3 weeks. An angiotensin receptor blockade maintains blood pressure-lowering efficacy at 3400 m but not at 5400 m.

Renin–Angiotensin–Aldosterone System Is Not Involved in the Arterial Stiffening Induced by Acute and Prolonged Exposure to High Altitude

“…41 Conversely, telmisartan lost its ability to reduce BP during prolonged exposure to very HA, likely because of the above reported suppression of RAAS. 24 In line with these findings, we also observed no difference in parameters reflecting viscoelastic properties of large arteries, such as PWV and other variables obtained from pulse wave analysis, including subendocardial oxygen supply and demand ratio, between telmisartan-treated and untreated subjects at any altitude. Thus, our study provides unequivocal and novel evidence on the fact that RAAS does not play any relevant role in explaining arterial wall-property changes during acute and prolonged exposition at very HA.…”

“…Changes in plasma noradrenaline, renin, serum angiotensin, and aldosterone levels in both treatment groups throughout the study have been shown in detail in a previous study of ours focusing on ambulatory BP. 24 In brief, type-1 angiotensin II receptor blocker induced, as expected, a significant increase in angiotensin II (P=0.001) and renin (P=0.003) plasma values at SL, although all these variables were significantly reduced under acute exposure to 5400 m (P<0.001), with a tendency to increase again after 2 weeks at this altitude. In the placebo group, angiotensin II, renin, and aldosterone were significantly The Lake Louise score was ≥3 (considered as indicative of acute mountain sickness) in 9 subjects at Namche, in 22 subjects at BC1, and in 3 subjects at BC2.…”

“…In HIGHCARE study, we showed that exposure to HA hypoxia is accompanied by a significant increase in plasma noradrenalin proportional to the altitude reached. 24 This sympathetic activation persisted throughout the time spent at HA. The muscular arteries are much more sensitive than elastic arteries to sympathetic nervous system activity, and, therefore, the weak and insignificant increase in carotid-radial PWV with altitude suggests that other factors, in addition to sympathetic activation, may 26,27 hemoconcentration with consequent increase in blood viscosity, 28 and interstitial edema 29 of the arterial wall, may have an important role in determining the changes in arterial distensibility observed in this condition.…”

“…Also in subjects treated with angiotensin receptor blocker, after the expected increase in their concentration at SL, angiotensin II and renin plasma values significantly fell at very HA. 24 We have previously shown that during short exposure to lower altitudes (≈3400 m) when RAAS at least partly retains its activity, the angiotensin antagonist telmisartan remains effective in BP lowering both in normotensive 24 and in hypertensive subjects. 41 Conversely, telmisartan lost its ability to reduce BP during prolonged exposure to very HA, likely because of the above reported suppression of RAAS.…”

Do People Live at Sea Level and the Dead Sea Level Have Different Patterns of Anti-Hypertensive Drugs

“…According to the study of Luks (2007), no clear mechanisms explaining the increased blood pressure at high altitudes and further, guidelines or patient-centered strategies to control patients with hypertension at high altitudes are not well accepted. In their study, Parati et al (2014) showed that treatment using the angiotensin receptor blocker telmisartan led to a minor decrease in the 24 h ambulatory BP at 3400 m altitude, but had no effect on BP at 5400 m altitude. We think that these findings are important and could have impacts on the choice of antihypertensive treatment during travel to high altitude.…”