The effects of exposure to moderate altitude on cardiovascular autonomic function in normal subjects

Veglio, M; Maule, Simona; Cametti, Gianni; Cogo, Annalisa; Lussiana, Livio; Madrigale, G.; Pecchio, Oriana

doi:10.1007/bf02281624

Cited by 39 publications

(32 citation statements)

References 15 publications

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“…However, no sex difference and no difference in the physiological response to hypoxia over a wide age range from 8 to 83 years have been reported. 33 We have previously found, for a large number of subjects, that resting MBF was slightly higher in women than in men but that no sex differences existed during hyperemia. 34 Thus, although we have no data on female volunteers in the present study, one can reasonably anticipate that potential sex differences would not have significantly changed our results with regard to stress perfusion measurement.…”

Section: Discussionmentioning

confidence: 86%

Influence of Altitude Exposure on Coronary Flow Reserve

et al. 2003

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Background-Although no data exist on the effect of altitude exposure on coronary flow reserve (CFR), patients with coronary artery disease (CAD) are advised not to exceed moderate altitudes of Ϸ2500 m above sea level. We studied the influence of altitude on myocardial blood flow (MBF) in controls and CAD patients. Methods and Results-In 10 healthy controls and 8 patients with CAD, MBF was measured by positron emission tomography and 15 O-labeled water at rest, during adenosine stress, and after supine bicycle exercise. This protocol was repeated during inhalation of a hypoxic gas mixture corresponding to an altitude of 4500 m (controls) and 2500 m (CAD). Workload was targeted to comparable heart rate-blood pressure products at normoxia and hypoxia. Resting MBF increased significantly in controls at 4500 m (ϩ24%, PϽ0.01) and in CAD patients at 2500 m (ϩ24%, PϽ0.05). Altitude had no influence on adenosine-induced hyperemia and CFR. Exercise-induced hyperemia increased significantly in controls (ϩ38%, PϽ0.01) at 4500 m (despite a reduction in workload, Ϫ28%, PϽ0.0001) but not in CAD patients at 2500 m (moderate decrease in workload, Ϫ11%, PϽ0.05). Exercise-induced reserve was preserved in controls (ϩ10%, PϭNS) but decreased in CAD patients (Ϫ18%, PϽ0.005). Conclusions-At 2500 m altitude, there is a significant decrease in exercise-induced reserve in CAD patients, indicating that compensatory mechanisms might be exhausted even at moderate altitudes, whereas healthy controls have preserved reserve up to 4500 m. Thus, patients with CAD and impaired CFR should be cautious when performing physical exercise even at moderate altitude.

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Section: Discussionmentioning

confidence: 86%

Influence of Altitude Exposure on Coronary Flow Reserve

et al. 2003

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“…Except for very short exposures to hypoxia (where hypoxiadependent vasodilation may prevail), studies in animals and healthy normotensive individuals have repeatedly documented that conventional BP undergoes a marked increase during acute exposures to altitudes of ≥3000 m. [23][24][25][26][27] In healthy normotensive subjects, an increase in ambulatory BP was also shown, 17,28,29 which becomes progressively more marked as the altitude increases, with a concomitant reduction, at high altitudes, of the nocturnal BP dipping. 17 The present study shows that similar changes occur in hypertensive subjects, regardless of the presence of antihypertensive treatment.…”

Section: Discussionmentioning

confidence: 99%

“…Excepto por exposiciones muy cortas a hipoxia (en donde puede prevalecer la vasodilatación dependiente de la hipoxia), los estudios en animales y en individuos normotensos sanos han documentado repetidas veces que la PA convencional sufre un aumento marcado durante las exposiciones agudas a altitudes ≥ 3000 m. [23][24][25][26][27] En sujetos normotensos sanos, también se mostró un aumento de la PA ambulatoria, 17,28,29 que se hace cada vez más pronunciado a medida que aumenta la altitud, con una reducción concomitante, en altitudes elevadas, del descenso de la PA nocturna. 17 Este estudio muestra que se producen cambios similares en los sujetos hipertensos, independientemente de la presencia de un tratamiento antihipertensivo.…”

Section: Debateunclassified

Ambulatory Blood Pressure in Untreated and Treated Hypertensive Patients at High Altitude

et al. 2015

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A cute exposure to high-altitude hypoxia induces important changes in cardiovascular regulation, [1][2][3][4] including an increase in blood pressure (BP) and heart rate (HR). 2,[5][6][7][8] Millions of subjects travel for relatively short periods of time to high altitude either for work or for leisure including many affected by hypertension 9 in whom the pressor effect of high altitude may be relevant. Limited information is available, however, on the acute BP effects of high altitude in hypertensive subjects, 10 and on the effectiveness and tolerability of antihypertensive drugs under these circumstances. As a result, the few recommendations published on the management of hypertensive subjects planning to spend time at high altitude for either leisure or work are largely based on experts' opinion rather than on evidence. 2,[11][12][13][14] Both angiotensin receptor blockers (ARBs) and dihydropyridine calcium antagonists are widely used for the monotherapy of hypertension, and their combination has been included among the preferred therapeutic choices by recent Abstract-Blood pressure increases during acute exposure to high altitude in healthy humans. However, little is known on altitude effects in hypertensive subjects or on the treatment efficacy in this condition. Objectives of High Altitude Cardiovascular Research (HIGHCARE)-Andes Lowlanders Study were to investigate the effects of acute high-altitude exposure on 24-hour ambulatory blood pressure in hypertensive subjects and to assess antihypertensive treatment efficacy in this setting. One hundred untreated subjects with mild hypertension (screening blood pressure, 144.1±9.8 mm Hg systolic, 92.0±7.5 mm Hg diastolic) were randomized to double-blind placebo or to telmisartan 80 mg+modified release nifedipine 30 mg combination. Twenty-four-hour ambulatory blood pressure monitoring was performed off-treatment, after 6 weeks of treatment at sea level, on treatment during acute exposure to high altitude (3260 m) and immediately after return to sea level. Eighty-nine patients completed the study (age, 56.4±17.6 years; 52 men/37 women; body mass index, 28.2±3.5 kg/ m 2 ). Twenty-four-hour systolic blood pressure increased at high altitude in both groups (placebo, 11.0±9 mm Hg; P<0.001 and active treatment, 8.1±10.4 mm Hg; P<0.001). Active treatment reduced 24-hour systolic blood pressure both at sea level and at high altitude (147.9±11.1 versus 132.6±12.4 mm Hg for placebo versus treated; P<0.001; 95% confidence interval of the difference 10.9-19.9 mm Hg) and was well tolerated. Similar results were obtained for diastolic, for daytime blood pressure, and for nighttime blood pressure. Treatment was well tolerated in all conditions. Our study demonstrates that (1) 24-hour blood pressure increases significantly during acute high-altitude exposure in hypertensive subjects and (2) treatment with angiotensin receptor blocker-calcium channel blocker combination is effective and safe in this condition. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique...

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“…However, no difference in the physiologic response to hypoxia over a wide age range from 8 to 83 years has been reported. 44 No additional measurements were performed during hyperemia to assess flow reserve (hyperemic/baseline flow) because of ethical reasons (restricted amount of radioactivity). Thus no firm conclusion on the influence of hyperemia on the myocardial flow reserve can be drawn.…”

Section: Study Limitationsmentioning

confidence: 99%