Search results for "Tilt test"
showing 4 items of 4 documents
Quantifying multidimensional control mechanisms of cardiovascular dynamics during multiple concurrent stressors
2021
Heartbeat regulation is achieved through different routes originating from central autonomic network sources, as well as peripheral control mechanisms. While previous studies successfully characterized cardiovascular regulatory mechanisms during a single stressor, to the best of our knowledge, a combination of multiple concurrent elicitations leading to the activation of different autonomic regulatory routes has not been investigated yet. Therefore, in this study, we propose a novel modeling framework for the quantification of heartbeat regulatory mechanisms driven by different neural routes. The framework is evaluated using two heartbeat datasets gathered from healthy subjects undergoing p…
Hipertensión arterial episódica asociada al síndrome de taquicardia postural ortostática
2006
Se presenta el caso clínico de una mujer de 17 años de edad que acude en reiteradas ocasiones a urgencias por palpitaciones, taquicardia, síncope, reacción vegetativa de escasa duración, con recuperación espontánea y completa y detección de cifras elevadas de presión arterial. Estudiada en diversas consultas de especialidades y tras múltiples exploraciones complementarias no se encontró patología que justificase el cuadro. Ante la sospecha de intolerancia ortostática o síndrome de taquicardia postural ortostática con hipertensión se realizó la prueba de estimulación con cama basculante a 60°, confirmándose el diagnóstico y comprobando la desaparición de los síntomas al iniciar tratamiento c…
Causal relationships in the variability of cardiovascular system evoked by orthostatic stress by transfer entropy.
2015
The coupling between cardiac and vascular systems in healthy volunteers, elicited by the head-up tilt test is estimated by means of transfer entropy with non-uniform embedding. The method applied to beat-to-beat recordings with heart periods and systolic blood pressure, supports the commonly accepted model, that baroreflex is the key factor in maintaining homeostatic blood distribution after tilting. However the method applied to changes of heart periods and changes of blood pressure, display switches in the driving system, from vascular in the early tilt, to cardiac just after the early tilt and back to vascular in the late tilt.
Information Decomposition: A Tool to Dissect Cardiovascular and Cardiorespiratory Complexity
2017
This chapter reports some recent developments of information-theoretic concepts applied to the description of coupled dynamical systems, which allow to decompose the entropy of an assigned target system into components reflecting the information stored in the system and the information transferred to it from the other systems, as well as the nature (synergistic or redundant) of the information transferred to the target. The decomposition leads to well-defined measures of information dynamics which in the chapter will be defined theoretically, computed in simulations of linear Gaussian systems and implemented in practice through the application to heart period, arterial pressure and respirat…