RESUMEN
The electrophysiological response to hyperkalaemia was reinvestigated in the whole dog for several reasons including: the paucity of comparative electrophysiological and electrocardiographical studies in which atrial and ventricular tissues were simultaneously investigated; the contrast between the clarity of findings in previous in vitro studies as compared with the rather conflicting results in earlier in vivo investigations; and the difficulty in validating the extrapolation from in vitro results and theory to the in vivo situation because of deficiences in the literature. Biphasic alterations in atrial and ventricular conduction times as well as excitability in response to progressively increasing hyperkalaemia were documented. The alterations in conduction times were reflected quite accurately by relevant electrocardiographical changes. Experiments in the whole animal were designed to test predictions based on membrane theory: the results offering strong support for the validity of extrapolating from the in vitro to the in vivo situation. The results of this study should help clarify and render interpretable many of the seemingly conflicting results in the literature.
Asunto(s)
Corazón/fisiopatología , Hiperpotasemia/fisiopatología , Animales , Perros , Electrocardiografía , Electrofisiología , Atrios Cardíacos/fisiopatología , Sistema de Conducción Cardíaco/fisiopatología , Ventrículos Cardíacos/fisiopatologíaRESUMEN
Environmental protection of Antarctica is a fundamental principle of the Antarctic Treaty. Impact assessment and significance evaluation are due for every human activity on the remote continent. While chemical and biological contaminations are widely studied, very little is known about the electromagnetic pollution levels. In this frame, we have evaluated the significance of the impact of Mario Zucchelli Antarctic Station (Northern Victoria Land) on the local geomagnetic field. We have flown a high resolution aeromagnetic survey in drape mode at 320m over the Station, covering an area of 2km(2). The regional and the local field have been separated by a third order polynomial fitting. After the identification of the anthropic magnetic anomaly due to the Station, we have estimated the magnetic field at the ground level by downward continuation with an original inversion scheme regularized by a minimum gradient support functional to avoid high frequency noise effects. The resulting anthropic static magnetic field at ground extends up to 650m far from the Station and reaches a maximum peak to peak value of about 2800nT. This anthropic magnetic anomaly may interact with biological systems, raising the necessity to evaluate the significance of the static magnetic impact of human installations in order to protect the electromagnetic environment and the biota of Antarctica.
Asunto(s)
Monitoreo del Ambiente/métodos , Campos Magnéticos , Regiones Antárticas , Ambiente , Contaminación Ambiental/estadística & datos numéricos , Actividades Humanas , HumanosAsunto(s)
Auscultación Cardíaca , Hipertensión Pulmonar/etiología , Insuficiencia de la Válvula Mitral/etiología , Infarto del Miocardio/complicaciones , Enfermedad Aguda , Anciano , Cateterismo Cardíaco , Gasto Cardíaco , Electrocardiografía , Frecuencia Cardíaca , Hemodinámica , Humanos , Venas Yugulares , Masculino , Fonocardiografía , Postura , Recurrencia , Presión VenosaAsunto(s)
Arritmia Sinusal/fisiopatología , Nodo Sinoatrial , Adolescente , Adulto , Anciano , Arritmia Sinusal/complicaciones , Bradicardia/complicaciones , Bradicardia/fisiopatología , Niño , Preescolar , Electrocardiografía , Femenino , Bloqueo Cardíaco/complicaciones , Bloqueo Cardíaco/genética , Bloqueo Cardíaco/fisiopatología , Sistema de Conducción Cardíaco/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , SíndromeAsunto(s)
Enfermedad Coronaria/fisiopatología , Digoxina/administración & dosificación , Insuficiencia Cardíaca/fisiopatología , Hemodinámica , Infarto del Miocardio/fisiopatología , Anciano , Presión Sanguínea , Superficie Corporal , Gasto Cardíaco , Enfermedad Coronaria/complicaciones , Digoxina/farmacología , Digoxina/toxicidad , Electrocardiografía , Femenino , Insuficiencia Cardíaca/etiología , Frecuencia Cardíaca , Ventrículos Cardíacos/fisiopatología , Humanos , Inyecciones Intravenosas , Masculino , Persona de Mediana Edad , Infarto del Miocardio/complicaciones , Potasio/sangre , Arteria Pulmonar , Taquicardia/inducido químicamente , Resistencia VascularAsunto(s)
Arritmias Cardíacas/etiología , Infarto del Miocardio/complicaciones , Ansiedad , Arritmia Sinusal/etiología , Arritmia Sinusal/terapia , Arritmias Cardíacas/tratamiento farmacológico , Arritmias Cardíacas/terapia , Bradicardia/etiología , Bradicardia/terapia , Unidades de Cuidados Coronarios , Cardioversión Eléctrica , Electrocardiografía , Electrofisiología , Insuficiencia Cardíaca/complicaciones , Hemodinámica , Humanos , Hipoxia/complicaciones , Monitoreo Fisiológico , Taquicardia/etiología , Taquicardia/terapia , Fibrilación Ventricular/etiología , Fibrilación Ventricular/terapiaRESUMEN
Nine cases of alternation of the atrial cycles during supraventricular tachycardia are presented, three of which were manifestly due to digitalis toxicity. They presented the following features: absence of 1/1 conduction, upright P waves in Lead II, atrial rates of 156-218. When alternation disappeared, the atrium adopted the longest of the previously inscribed cycles. A ventriculophasic cause was excluded. The possible mechanisms are discussed in terms of the known functional anatomy of the various forms of SVT.