Électrocardiographie | EPFL Graph Search

vignette|L'électrocardiographie est la technique d'enregistrement des courants électriques accompagnant les contractions du cœur. Elle est réalisée grâce à un électrocardiographe relié au patient par des électrodes. vignette|Un électrocardiogramme est une représentation graphique sur papier de l'activité électrique du cœur. L'électrocardiographie (ECG) est une représentation graphique de l'activité électrique du cœur. Cette activité électrique est liée aux variations de potentiel électrique des cellules spécialisées dans la contraction (myocytes) et des cellules spécialisées dans l'automatisme et la conduction des influx. Elle est recueillie par des électrodes à la surface de la peau. L'électrocardiogramme est le tracé papier de l'activité électrique dans le cœur. L'électrocardiographe est l'appareil permettant de faire un électrocardiogramme. L'électrocardioscope, ou scope, est un appareil affichant le tracé sur un écran. C'est un examen rapide ne prenant que quelques minutes, indo

Electrical spinal cord stimulation protocols to regulate neurological functions after spinal cord injury

Salif Axel Komi

Spinal cord injury (SCI) is a life-changing event. People who suffer from it lose their abilityto move normally and are subject to life-threatening symptoms. When the insult is not toosevere, partial recovery is possible. Otherwise, for severely affected people, the perspectives toever retrieve normal functions is almost non-existent. A critically important window to promoteplasticity is in the acute phase after the trauma (weeks to months). However, at this stage,people cannot take active part in rehabilitation programs due to their incapacity to activate theirlimbs and to the apparition of severe autonomic symptoms such as orthostatic hypotension.Hence, current activity-based treatments are of little help for this population. Consequently, SCIdramatically affects their autonomy and quality of life on the life-long term.Continuous Epidural Electrical Stimulation (EES) of the spinal cord has been proposed as amethod to reactivate dormant neural networks innervated below the site of injury. It enablesrobust control over locomotion and autonomic functions. In animal models of severe lesion,continuous EES promoted long lasting recovery of motor abilities when coupled with an intensivetraining. In human, its recent application indeed supported overground walking in chronicallyand severely injured people, but only showed limited plastic effects when compared to animals.Why? Recent advances support that continuous EES abolishes proprioceptive feedback thatis essential to promote recovery. Moreover, late treatment of severe injuries consistently fail apromoting recuperation of functions. Alternatively, over the last decade, our laboratory developeda spatio-temporally patterned approach to EES. In addition to restore fine control over motorfunctions, this technique avoids the caveats of continuous EES, and hypothetically opens a windowof opportunity for plasticity to happen. In this thesis, we propose a translation of this concept tohumans. We first demonstrate that spatio-temporal EES restores robust and versatile locomotorcontrol in people with chronic incomplete, though severe, SCI. Furthermore, the results supportan aptitude of this approach to promote long lasting recovery of functions without stimulationafter 5 months of intensive training. We then report on a patient-tailored technology, thatincludes personalized computational models enabling precise pre-operative planning strategies, anew electrode-lead and control softwares. This technology enables restoration of various motorfunctions in people with chronic and motor-complete injuries within few hours after beginningof therapy. Finally, we transfer this targeted approach to the control of blood pressure. Wedemonstrate that closed-loop stimulation protocols support a precise control over arterial bloodpressure in rodents, non-humane primates and humans with severe SCI submitted to challengingcardiovascular conditions. Combined, the results presented in this manuscript open a clinicallyrealistic perspective for the application of EES acutely after injury and to potentially promoterobust recovery in severe SCI.

EPFL2021

Intracardiac organization indices for the monitoring of atrial fibrillation

Sarah Volorio

Atrial fibrillation (AF) is the most common arrhythmia observed in clinical practice. It is responsible for about one third of hospitalizations related to problems of arrhythmia. AF is an important clinical entity due to the increased risk of morbidity and mortality. The consequences of AF most frequently found are hemodynamic function impairment (loss of atrial synchronized contraction, irregular and inadequately rapid ventricular rate), atriogenic thromboembolic events and tachycardia induced atrial and ventricular cardiomyopathy. With the present increase of life expectancy, AF prevalence is expected to double in the next fifty years, in particular in western countries. In collaboration with the Division of Cardiology of CHUV, a catheter ablative protocol mainly based on pulmonary vein isolation (PVI) and complex fractionated elctrograms ablations was defined in order to develop new strategies to decrease procedural time and ablation extent. More precisely, surface EGC as intracardiac electrogram (EGM) signals were recorded from different catheters at specific locations before ablation during and after PVI. The purpose of this project is to evaluate the ability of known (AF cycle length) and new intracardiac organization indices based on recorded surface ECGs and EGM signals to monitor AF organization during stepwise ablation of persistent AF.

2011

ECG-based prediction of atrial fibrillation development following coronary artery bypass grafting

Sinisa Sovilj

In patients undergoing coronary artery bypass grafting (CABG) surgery, post-operative atrial fibrillation (AF) occurs with a prevalence of up to 40%. The highest incidence is seen between the second and third day after the operation. Following cardiac surgery AF may cause various complications such as hemodynamic instability, heart attack and cerebral or other thromboembolisms. AF increases morbidity, duration and expense of medical treatments. This study aims at identifying patients at high risk of post-operative AF. Early prediction of AF would provide timely prophylactic treatment and would reduce the incidence of arrhythmia. Patients at low risk of post-operative AF could be excluded on the basis of the contraindications of anti-arrhythmic drugs. The study included 50 patients in whom lead II electrocardiograms were continuously recorded for 48 h following CABG. Univariate statistical analysis was used in the search for signal features that could predict AF. The most promising ones identified were P wave duration, RR interval duration and PQ segment level. On the basis of these, a nonlinear multivariate prediction model was made by deploying a classification tree. The prediction accuracy was found to increase over time. At 48 h following CABG, the measured best smoothed sensitivity was 84.8% and the specificity 85.4%. The positive and negative predictive values were 72.7% and 92.8%, respectively, and the overall accuracy was 85.3%. With regard to the prediction accuracy, the risk assessment and prediction of post-operative AF is optimal in the period between 24 and 48 h following CABG.

Institute of Physics2010

Electrical spinal cord stimulation protocols to regulate neurological functions after spinal cord injury

Salif Axel Komi

EPFL2021