Physiologic condition of the heart in the natives of high altitudes

Rotta, Andrés

doi:10.1016/0002-8703(47)90083-5

Cited by 43 publications

(7 citation statements)

References 17 publications

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“…1 Complementary fluoroscopic studies have demonstrated that an increase inl the volume of the right cavities rather than a total involvement is responsible for heart enlargememmt. 4 More recently, by means of cardiac catheterization, a moderate but significant increase of the pulmonary artery pressure and of total pulmonary resistance has been found in men at high altitudes.6 Finally, a variable grade of right ventricular hypertrophy has been found in a small nurnber of postmortem observations on subjects at high altitudes dying from work accidents. 7 TIme preceding, information, as well as preliiminary eleetrocardiographie observations carried out at this same altitude,4 at lower altitudes,5 and on1 miners without pulmonary silicosis from various altitudes and studied at sea level after several days of residence9 suggests that normal miie living at high altitudes must show some electrocardiographie signs of right ventricular hypertrophy.…”

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Electrocardiographic Patterns in Man at High Altitudes

Rotta¹,

López²

1959

Circulation

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Electrocardiograims of healthy men both native and long-term residents at 14,900 feet above sea level have been obtained and classified according to their dominant pattern. Most of the tracings showed signs of either right ventricular hypertrophy or right bundle-branch block, incomplete and complete. Some of the mechanisms responsible for these electrocardiographic changes found at high altitudes, such as pulmonary hypertension, positional changes of the heart, and chronic hypoxia, are discussed.THIE effect of chronic hypoxia due to altitude oil the right side of the heart is of particular interest. Measurements made on teleroenitgeniogramiis of the heart of normal subjects living perinianieittly-at an altitude of 14,900 feet have shown an increase in the transverse diameter of the heart and in the cardiac silhouette area, as well as a prominent )ullIlOlary-coitus. 1 Complementary fluoroscopic studies have demonstrated that an increase inl the volume of the right cavities rather than a total involvement is responsible for heart enlargememmt.4More recently, by means of cardiac catheterization, a moderate but significant increase of the pulmonary artery pressure and of total pulmonary resistance has been found in men at high altitudes.6 Finally, a variable grade of right ventricular hypertrophy has been found in a small nurnber of postmortem observations on subjects at high altitudes dying from work accidents.7TIme preceding, information, as well as preliiminary eleetrocardiographie observations carried out at this same altitude,4 at lower altitudes,5 and on1 miners without pulmonary silicosis from various altitudes and studied at sea level after several days of residence9 suggests that normal miie living at high altitudes must show some electrocardiographie signs of right ventricular hypertrophy. The work reported here was designed to shed some light on this problem. Accordingly, electrocardiograms of a group of normal subjects residing at higlh altitudes were taken and compared with normal staiidards at sea level. Electrocardiog ramiis were taken during rest in the supine position, with Sanborn Viso-Cardiette and Cambridge Simple-Trol electrocardiographs.The standard leads, 3 augmented unipolar limb leads, and 7 unipolar precordial leads from RV3 to V6 were recorded. In 18 instances RV3 was not registered; in 5 cases, the VE lead was recorded instead of RVY, and in 6 additional cases leads from right precoidiumai (RV4, RV5, and RV6) were taken. In all tracings height and duration of the P, R, S, and T waves in standard and precordial leads were tmeasured. The ventricular activation time (tinte of onset of the intrinsic deflection), from the beginning of QRS complex to the peak of R wave, was measured in V1, V5, and V6. The mean electric axis of QRS and the R/S ratio in V1, V,, and V6 were determined.

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Electrocardiographic Patterns in Man at High Altitudes

Rotta¹,

López²

1959

Circulation

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“…Residents at high altitudes have a lower blood pressure and lower incidence of hypertension than sea level control subjects. 16 Several authors have reported blunting of the usual rise in blood pressure when SHR 17 -) 9 or renal hypertensive rats 20 are exposed to chronic, continuous high-altitude hypoxia. Lund and Tomanek 21 reported a reduction in blood pressure in rats exposed to dairy continuous hypoxia for 6 weeks.…”

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Sympathetic denervation blocks blood pressure elevation in episodic hypoxia.

et al. 1992

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We have previously described a rat model that responds to repetitive episodic hypoxia (FiO 2 nadir 3-5% for 12 seconds every 30 seconds for 7 hr/day for 35 days) with chronic increase in arterial blood pressure. The purpose of the current study was to determine if peripheral sympathetic nervous system denervation blocks this persistent blood pressure elevation. Chemical sympathetic denervation was achieved and maintained by three intraperitoneal injections (100 mg/kg 6-hydroxydopamine) on days 1, 3, and 27 of a 47-day experiment in two groups of rats. One denervated group was subjected to episodic hypoxia for 40 consecutive days beginning on day 7 and the other remained unhandled in their usual cages. A third group was injected with vehicle only and subjected to the same episodic hypoxia while a fourth group remained unhandled for 40 days. The vehicle-treated, episodic hypoxia-exposed group showed a 7.7 mm Hg increase in mean arterial blood pressure (conscious, unrestrained) over the 40-day period, whereas all other groups showed a decrease in mean arterial pressure. The left ventricle and septum/whole body weight ratio was higher in both episodic hypoxia-exposed groups at the end of the study. Plasma epinephrine in both groups administered 6-hydroxydopamine was higher on day 6 than in the vehicle-injected rats. Measurement of catecholamines in cardiac muscle homogenate confirmed denervation in 6-hydroxydopamine animals. These results indicate that the peripheral sympathetic nervous system is necessary for the persistent increase in blood pressure in response to repetitive episodic hypoxia. emia is associated with acute elevation of blood pressure, and in up to 50% of patients with chronic apnea, persistent elevation of daytime blood pressure is seen. '-3 Repetitive acute hypoxia with heightened sympathetic nerve activity could play an important role in the persistent elevation of blood pressure seen in some patients.With some species variability, acute hypoxemia causes increased heart rate, variable changes in arterial pressure, and increased cardiac contractility and output through stimulation of central and peripheral chemoreceptors and perhaps other local effects.4 -6 The effector arm of this reflex involves increased sympathetic discharge. Plasma norepinephrine is elevated in acute hypoxia, 7 -8 and urinary catecholamine elevation in patients with severe sleep apnea is reversed by tracheostomy.9 Acute hypoxia induces elevated blood pressure and increased microneurographic amplitude, implying increased postganglionic sympathetic activity. 1011 In spontaneously hypertensive rats (SHR) 12 and in humans with borderline hypertension, the sympathetic response to acute hypoxia is exaggerated. 13 The response is further exaggerated in borderline hypertensive humans when apnea is added to acute hypoxia.14 Finally, muscle nerve sympathetic activity recorded during apnea in humans shows a progressive increase throughout the apnea followed by an abrupt reduction at apnea termination. 15A key concept in the above hy...

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“…There is extensive knowledge concerning altered cardiopulmonary function in natives residing at high altitude (1)(2)(3)(4)(5) and in mountaineers staying at altitude for a short period (6)(7)(8)(9)(10). Until the Indo-Chinese mili-(Received in revised form November 30, 1971) 1 From the Respiratory Group, Defence Institute of Physiology and Allied Sciences, New Delhi, India.…”

Section: Introductionmentioning

confidence: 99%

“…Until the Indo-Chinese mili-(Received in revised form November 30, 1971) 1 From the Respiratory Group, Defence Institute of Physiology and Allied Sciences, New Delhi, India.…”

Section: Introductionmentioning

confidence: 99%

Study of Cardiopulmonary Function on Exposure to High Altitude

Kamat¹,

Rao²,

Sarma³

et al. 1972

Am Rev Respir Dis

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_The effects of a prolonged stay at high altitude was studied in 513 immigrants accustomed to living at sea level and 92 natives accustomed to high altitudes. The immigrants had higher pulse rates, and a larger number of them (23.8 per cent), compared with the natives (14.1 per cent) manifested persistent rales in the lungs. Rales increased after a stay of 3 to 12 months. Diastolic blood pressure increased in immigrants who stayed longer. During brief exercise, the performance in both groups was similar, but during endurance tests the natives performed better and recovered sooner. Peak expiratory flows decreased to 536 liter per min in those staying a short time and to 485 liter per min for those staying more than 12 months.Despite long stays at high altitudes, some subjects showed incomplete acclimatization that did not improve with continued stay. Adequacy of adaptation could be judged by serial measurements of peak expiratory flow.Reversal of the effects of altitude was studied in 217 immigrants. The increase in blood pressure, pulse rate, and maximal breathing capacity and the decrease in peak expiratory flow disappeared. Symptoms of altitude disability and evidence of lung congestion disappeared in most subjects.

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Physiologic condition of the heart in the natives of high altitudes

Cited by 43 publications

References 17 publications

Electrocardiographic Patterns in Man at High Altitudes

Electrocardiographic Patterns in Man at High Altitudes

Sympathetic denervation blocks blood pressure elevation in episodic hypoxia.

Study of Cardiopulmonary Function on Exposure to High Altitude

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