Improvement of myocardial perfusion in coronary patients after intermittent hypobaric hypoxia.

BACKGROUND: Persons living at high altitude (exposed to hypoxia) have a greater number of coronary and peripheral branches in the heart than persons living at sea level. In this study we investigated the effect of intermittent hypobaric hypoxia on myocardial perfusion in patients with coronary heart disease. METHODS AND RESULTS: We studied 6 male patients (aged>or=53 years) with severe stable coronary heart disease. All patients were born at sea level and lived in that environment. They underwent 14 sessions of exposure to intermittent hypobaric hypoxia (equivalent to a simulated altitude of 4200 m). Myocardial perfusion was assessed at baseline and after treatment with hypoxia by use of exercise perfusion imaging with technetium 99m sestamibi. After the sessions of hypoxia, myocardial perfusion was significantly improved. The summed stress score for hypoperfusion, in arbitrary units, decreased from 9.5+ to 4.5+ after treatment (P=.036). There was no evidence of impairment of myocardial perfusion in any patient after treatment. CONCLUSIONS: Intermittent hypobaric hypoxia improved myocardial perfusion in patients with severe coronary heart disease. Though preliminary, our results suggest that exposure to intermittent hypobaric hypoxia could be an alternative for the management of patients with chronic coronary heart disease.

Cross-sectional study of echocardiographic characteristics in healthy children living at high altitude.

Non-echocardiographic studies in healthy high altitude children have shown right ventricle predominance during infancy and childhood, associated to asymptomatic pulmonary hypertension and an increased pulmonary artery pressure. Systematic studies on echocardiography in such children have not been performed. In a cross-sectional study, we measured right and left heart morphologic and functional parameters, through M-mode, two-dimensional Doppler, and color Doppler echocardiographies, in a population of 321 healthy children ranging in age from 2 months to 19 years and living at high altitude (Tintaya, Peru, 4,100 m). Structured ad-hoc interviews were done to obtain information on medical history, patterns of exposure to high altitude of children and their parents and grandparents, place and altitude of pregnancy and birth, and housing conditions. A complete physical examination was performed before echocardiography. Hemoglobin concentration, pulse oximetry, and anthropometry were measured in all participating children. The right and left heart morphologic and functional echocardiographic measurements expressed by age and by body surface area were generally similar to sea-level reference populations. They were not consistently influenced by sex, nutritional status, chest dimensions, pulse oximetry, hemoglobin concentration, ethnicity, length of residence at high altitude, or parental history of exposure to high altitude. Most children had at least some degree of high-altitude ancestry as assessed by ethnicity and history of parental exposure to altitude. The cardiovascular development at high altitude in children with some degree of high-altitude ancestry seems to follow a pattern similar to sea-level children. The results can be used as reference values to interpret individual echocardiographic studies in comparable children living in similar settings.

Bioenergetics of the heart at high altitude: environmental hypoxia imposes profound transformations on the myocardial process of ATP synthesis.

The low concentration of O2 in the thin air at high altitude is undoubtedly the reason for the remarkable modifications in the structure and function of the heart, lung, and blood of humans permanently living under these conditions. The effect of natural hypoxia on the energy metabolism of the cell is however not well understood. Here we study the proces of ATP synthesis in the heart of guinea pigs native to high altitude (4500 m) as compared with those native to sea level. The following are the novel findings of this study. (1) The rates and extents of ATP synthesis in the presence of low concentrations of ADP (<30 microM) are significantly higher at high altitude than at sea level. (2) The Hill coefficient, i.e. the degree of cooperativity between the three catalytic sites of the ATP synthase, is lower at high altitude (n = 1.36) than at sea level (n = 1.94). (3) Both, the affinity for ADP and the fractional occupancy of the catalytic sites by ATP, are higher at high altitude than at sea level but the P50, i.e. the concentration of ADP at which 50% of the catalytic sites are filled with ADP and/or ATP, is the same (approximately 74.7 microM). (4) In the physiological range of ADP concentrations, the phosphorylation potential deltaGp is significantly higher at high altitude than at sea level. It is concluded that the molecular mechanism of energy transduction is profoundly modified at high altitude in order to readily and efficiently generate ATP in the presence of low concentrations of O2 and ADP.

Entidades nosológicas de desadaptación aguda a la altura / Clinical pictures of acute high-altitudes sikness

Se efectúa revisión y se discute puntualmente entidades de desadaptacion aguda a la altura. Por implicancias clínicas y pronósticas se enfatiza entre ellas, al edema pulmonar y edema cerebral. Al respecto, se especifican las medidas preventivas y terapéuticas correspondientes.

2001 ¿Existe terapia farmacológica efectiva para el edema agudo pulmonar de altura? / 2001: Exists effective chemical therapy for edema acute pulmonary of hight?

Se reactualiza una clasificación de grados de severidad del edema agudo pulmonar de altura (EAPA) que puede facilitar el hallazgo de la/s drogas que farmacológicamente controlen con certeza esta entidad, que aún tiene riesgos letales y que al 2001 no ha sido resuelto con fármacos. Por estas razones es un buen momento para la divulgación de la clasificación que se propone. Se sustenta en: a) el avance en los mecanismos biológico-moleculares a nivel endotelial, b)el avance en los posibles mecanismos fisiopatológicos que intentan explicar el EAPA mediando hipertensión pulmonar súbita por ascenso rápido a la A y que desestabilizaría la microcirculación pulmonar y, c) Por lo simple que significa el registro de la frecuencia cardíaca y respiratoria. d) Finalmente esta clasificación por grados de severidad de EAPA al haberse estructurado a 3730 m. Podrá variar respecto a otros niveles de altitud u otras circunstancias de alta sensibilidad genética a la hipoxia, o la existencia de patología asociada especialemnte cardiopulmonar, por ejemplo.

Evaluación de métodos terapéuticos en el edema agudo pulmonar de altura: tratamiento y prevención / Evaluation of therapeutical methods in the acute pulmonary edema of high altitude: treatment and prevention

Se ha efectuado la evaluación del tratamiento con sólo reposo (SR) en 16 pacientes con edema agudo pulmonar de altura (EAPA) de grado leve a severo, en pacientes cuyo cuadro ocurrió a 3,730 metros de altura sobre el nivel del mar, La Oroya. El tratamiento de SR fue comparado con otros procedimientos: reposo + O2 y reposo + esteroides. En 4 pacientes se investigó la eficacia de la hidrocortisona, isoproterenol y digital endovenoso. Para facilitar nuestro estudio, se diseñó un sistema de evaluación de grado de severidad (GS) del EAPA, basado en síntomas y signos clínicos, así como hallazgos radiológicos electrocardiográficos y la frecuencia cardiáca y respiratoria. Los grupos tratados con las diferentes modalidades fueron similares en GS. El tratamiento en SR, permitió completa remisión el cuadro dentro de 60 horas promedio. No se tuvo resultados frustros. La combinación de reposo + O2, originó la más pronta remisión de los síntomas y signos y un ligero acortamiento del tiempo de recuperación. Los esteroides orales o endovenosos, el isoproterenol y la digitalización fueron inefectivos. En la prevención lo aconsejable es reposar de uno a dos días al arribo a la altura, así como ascender por etapas a grandes alturas. El uso de acetazolamide parece dismiuir la posibilidad de EAPA en pacientes que previamente la han padecido.

Impact and mid-term assessment of coronary patients rehabilated with intermittent simulated hypoxia technique

Main objetive of the present investigation were evaluate the impact of the simulated hypoxia technique - hypobaric chamber - to rehabilitate coronary bypassed patients with or without myocardial infarction. The following variable, pre and post rehabiliation four months program were explored: myocardial ischemia, arrythmia, late potencials, myocardium perfussion and molecular biochemistry. The last two were observed in a follow up of four months. results, shows general improvement. The follow up items, remained improved until protocol finish. Exercise was not utilized. Findigs are consider principally related to hypoxia. Mainly due to central rather than pheriphery recoveries.