The Pulmonary Circulation of High Altitude Natives

Antezana, Gerardo; Barragán, L. Muñoz; Coudert, J; Coudkowicz, L.; Durand, Jean-Luc; Lockhart, A; Mensch-Dechêne, J; Zamora, Megan; Spielvogel, Hilde; Vargas, Enrique; Zelter, Marta

doi:10.1007/978-1-4612-5639-7_19

Cited by 10 publications

(6 citation statements)

References 9 publications

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“…These changes correspond to increments of 100% at HA and 50% at SL (Table 4). Exercise-induced PH in highlanders was confirmed in subsequent studies performed in Leadville, Colo 19,20 ; La Paz, Bolivia 24 ; and La Oroya, Perú. 25 The magnitude of the pressure response was related to the level of altitude and the degree of submaximal workload.…”

Section: Pulmonary Pressure and Arterial Oxygen Saturation During Exementioning

confidence: 60%

“…32 Age is an important factor of variability. Newborns and infants are hyperreactive (34) 93 (34) Ordoñez (22) Bogota, Colombia 2600 13Ϯ3 (18) 90 (18) Grover (20) Leadville, Colo 3100 24Ϯ7 (50) 89 (50) Antezana et al (24) La Paz, Bolivia 3600 22Ϯ1 (11) 90Ϯ0.8 (11) Groves et al (29) Lhasa, Tibet 3600 15Ϯ1 (5) 88Ϯ1.8 (5) Yang et al (26) Yushu, Qinghai, China 3680 22Ϯ4 (17) ⅐ ⅐ ⅐ Hultgren et al (25) La Oroya, Peru 3700 22Ϯ4 (26) 85 (27) Yang et al (27) Chengdou …”

Section: Pap Arterial Oxygen Saturation and Level Of Altitudementioning

confidence: 99%

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The Heart and Pulmonary Circulation at High Altitudes

2007

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Abstract-More than 140 million people worldwide live Ͼ2500 m above sea level. Of them, 80 million live in Asia, and 35 million live in the Andean mountains. This latter region has its major population density living above 3500 m. The primary objective of the present study is to review the physiology, pathology, pathogenesis, and clinical features of the heart and pulmonary circulation in healthy highlanders and patients with chronic mountain sickness. A systematic review of worldwide literature was undertaken, beginning with the pioneering work done in the Andes several decades ago. Original articles were analyzed in most cases and English abstracts or translations of articles written in Chinese were reviewed. Pulmonary hypertension in healthy highlanders is related to a delayed postnatal remodeling of the distal pulmonary arterial branches. The magnitude of pulmonary hypertension increases with the altitude level and the degree of exercise. There is reversal of pulmonary hypertension after prolonged residence at sea level. Chronic mountain sickness develops when the capacity for altitude adaptation is lost. These patients have moderate to severe pulmonary hypertension with accentuated hypoxemia and exaggerated polycythemia. The clinical picture of chronic mountain sickness differs from subacute mountain sickness and resembles other chronic altitude diseases described in China and Kyrgyzstan. The heart and pulmonary circulation in healthy highlanders have distinct features in comparison with residents at sea level. Chronic mountain sickness is a public health problem in the Andean mountains and other mountainous regions around the world. Therefore, dissemination of preventive and therapeutic measures is essential. Key Words: altitude Ⅲ altitude sickness Ⅲ hypertension, pulmonary P eople native to high altitude (HA) environments live in an environment of hypobaric hypoxia with low ambient partial pressure of oxygen. As a consequence, they develop alveolar hypoxia, hypoxemia, and polycythemia. Despite this, healthy highlanders are able to perform physical activities similar to and often even more strenuous than those of people living at sea level (SL). This phenomenon has been ascribed to adaptive mechanisms that occur at sequential steps of the oxygen transport system with the main purpose of decreasing the total pO 2 gradient from ambient hypoxic air to mixed venous blood at the tissue level.The heart and pulmonary circulation in healthy people living at HA exhibit important physiological and anatomic characteristics, which resemble those that occur in chronic clinical conditions associated with alveolar hypoxia, hypoxemia, and polycythemia. Healthy HA natives have pulmonary hypertension (PH), right ventricular hypertrophy (RVH) and increased amount of smooth muscle cells (SMCs) in the distal pulmonary arterial branches. All these findings become exaggerated when healthy highlanders lose their capacity for adaptation and develop chronic mountain sickness (CMS). The physiological, pathological, pathogenic, and cl...

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Section: Pulmonary Pressure and Arterial Oxygen Saturation During Exementioning

confidence: 60%

Section: Pap Arterial Oxygen Saturation and Level Of Altitudementioning

confidence: 99%

The Heart and Pulmonary Circulation at High Altitudes

2007

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“…Conversely, an iron deficit, which was not assessed here, could explain the relatively low [Hb] in some subjects. The threshold of 4.7 kPa for Ppa was chosen according to previous invasive studies at the same altitude [13,17] and according to local experience with cardiac Doppler in healthy subjects (unpublished data). However, individuals with 5.3 kPa Ppa were not very different from those with 4.7 or 4.0 kPa, but were considered as hypertensive for this altitude.…”

Section: Discussionmentioning

confidence: 99%

“…Normal Ppa at this altitude is 4.3±0.40 kPa [13]. Patients were included in a low Ppa group (LPpa) when Ppa was ð4.7 kPa, and in a high Ppa group (HPpa) when Ppa was >4.7 kPa.…”

Section: Methodsmentioning

confidence: 99%

Pulmonary hypertension in high-altitude chronic hypoxia: response to nifedipine

Antezana

Antezana²,

Aparicio³

et al. 1998

Eur Respir J

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The vasoconstrictive effect of hypoxia upon pulmonary artery vessels is well known in most mammalian species, including humans. A pure form of hypoxic pulmonary artery hypertension can be seen in high-altitude residents. A loss of adaptation to chronic hypoxia, known as chronic mountain sickness (CMS), is observed in 5-10% of people sojourning above 3,000 m and is characterized by excessive polycythaemia (H-Hb), pulmonary hypertension and nonspecific neurological symptoms [1]. Ongoing pulmonary vasoconstriction leads to increased vascular resistance and pulmonary artery pressure (Ppa), which are probable maladaptive responses to high altitude since they result in minimal improvement in ventilation-perfusion matching and increased workload for the right ventricle.In addition to vasoconstriction, chronic alveolar hypoxia is associated with structural changes in the media of terminal portions of pulmonary arterioles [2], such as smooth muscle cell proliferation, thickening of the media, proliferation and turgescence of endothelial cells. Recently, this vascular remodelling has been found in only a few residents at high altitude [3], but it is admitted that sustained hypoxia is able to increase muscularization of the small pulmonary vessels and to increase even further the pulmonary vascular resistance.A reduction in Ppa, under hypoxic conditions, has been obtained by the calcium channel-blocker nifedipine in healthy humans exposed to acute normobaric hypoxia [4] or in subjects suffering from high-altitude pulmonary oedema in hypobaric hypoxia [5]. In other aetiologies of pulmonary hypertension, such as primary pulmonary hypertension [6] or secondary to obstructive pulmonary disease [7,8], nifedipine and felodipine were efficient in decreasing Ppa. Calcium antagonists have also been shown to be efficient in experimental hypoxic pulmonary vasoconstriction [9,10].Reversal of hypoxic pulmonary hypertension with calcium channel-blockers has not been evaluated in a population chronically exposed to high altitude. Venesection has been used to treat CMS, but no modification of pulmonary haemodynamics has been reported.The objectives of this study were to assess pulmonary hypertension in native residents at high-altitude by echocardiography, to analyse the relationship between Ppa and H-Hb, and to study the effect of acute administration of nifedipine on pulmonary pressure. In the presence of reversible vascular changes in altitude-induced pulmonary hypertension, a nifedipine-induced vasodilatation could be anticipated. Materials and methods SubjectsThirty males and one females, native residents of La Paz (3,500-4,100 m), Bolivia, were included in this nonrandomized study. Asymptomatic subjects were recruited Systolic pulmonary arterial pressure (Ppa) was studied by Doppler echocardiography, at rest and after sublingual nifedipine, in 31 asymptomatic residents at 3,600 m. Individuals were separated into two groups according to resting Ppa: a group with low Ppa (ð4.7 kPa, n=17) and a group with high Ppa (>4.7 kPa, n=14). Ind...

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“…T HE PARTIAL PRESSURE OF OXYGEN in inspired air falls with increasing terrestrial elevation above sea level. As a consequence of the hypobaric hypoxic environments, human residents at high altitudes develop numerous physiologic responses, including, in particular, increases in hemoglobin concentration [Hb] and pulmonary artery pressure (Antezana et al, 1982;Hurtado, 1964;Monge-M and Monge-C, 1966;Penaloza et al, 1963). In severely hypoxic residents, large increases in Hb and/or pulmonary artery pressure may be associated with potentially fatal illnesses (Hurtado, 1942;Monge-M et al, 1928;Winslow and Monge-C, 1987;Wu et al, 1998a).…”

Section: Introductionmentioning

confidence: 99%

Consensus Statement on Chronic and Subacute High Altitude Diseases

León‐Velarde

Maggiorini

Reeves

et al. 2005

High Altitude Medicine & Biology

507

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This is an international consensus statement of an ad hoc committee formed by the International Society for Mountain Medicine (ISMM) at the VI World Congress on Mountain Medicine and High Altitude Physiology (Xining, China; 2004) and represents the committee's interpretation of the current knowledge with regard to the most common chronic and subacute high altitude diseases. It has been developed by medical and scientific authorities from the committee experienced in the recognition and prevention of high altitude diseases and is based mainly on published, peer-reviewed articles. It is intended to include all legitimate criteria for choosing to use a specific method or procedure to diagnose or manage high altitude diseases. However, the ISMM recognizes that specific patient care decisions depend on the different geographic circumstances involved in the development of each chronic high altitude disease. These guidelines are established to inform the medical services on site who are directed to solve high altitude health problems about the definition, diagnosis, treatment, and prevention of the most common chronic high altitude diseases. The health problems associated with life at high altitude are well documented, but health policies and procedures often do not reflect current state-of-the-art knowledge. Most of the cases of high altitude diseases are preventable if on-site personnel identify the condition and implement appropriate care.

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The Pulmonary Circulation of High Altitude Natives

Cited by 10 publications

References 9 publications

The Heart and Pulmonary Circulation at High Altitudes

The Heart and Pulmonary Circulation at High Altitudes

Pulmonary hypertension in high-altitude chronic hypoxia: response to nifedipine

Consensus Statement on Chronic and Subacute High Altitude Diseases

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