Carolina Varon

Learn More
Early detection of seizures could reduce associated morbidity and mortality and improve the quality of life of patients with epilepsy. In this study, the aim was to investigate whether ictal tachycardia is present in focal and generalized epileptic seizures in children. We sought to predict in which type of seizures tachycardia can be identified before(More)
Recent studies show that principal component analysis (PCA) of heartbeats is a well-performing method to derive a respiratory signal from ECGs. In this study, an improved ECG-derived respiration (EDR) algorithm based on kernel PCA (kPCA) is presented. KPCA can be seen as a generalization of PCA where nonlinearities in the data are taken into account by(More)
It is well known that epilepsy has a profound effect on the autonomic nervous system, especially on the autonomic control of heart rate and respiration. This effect has been widely studied during seizure activity, but less attention has been given to interictal (i.e. seizure-free) activity. The studies that have been done on this topic, showed that heart(More)
One of the main challenges in unsupervised learning is to find suitable values for the model parameters. In kernel principal component analysis (kPCA), for example, these are the number of components, the kernel, and its parameters. This paper presents a model selection criterion based on distance distributions (MDDs). This criterion can be used to find the(More)
GOAL This paper presents a methodology for the automatic detection of sleep apnea from single-lead ECG. METHODS It uses two novel features derived from the ECG, and two well-known features in heart rate variability analysis, namely the standard deviation and the serial correlation coefficients of the RR interval time series. The first novel feature uses(More)
Epileptic seizures have a clear effect on the regulatory mechanisms of the autonomic nervous system, especially on the cardiac and respiratory controls. Changes in heart rate and respiration are well known to occur around the onset of the seizure. This paper studies the ECG signals recorded from patients suffering from epilepsy, whose ages ranged from 3 to(More)
In this paper a methodology to identify sleep apnea events is presented. It uses four easily computable features, three generally known ones and a newly proposed feature. Of the three well known parameters, two are computed from the RR interval time series and the other one from the approximate respiratory signal derived from the ECG using principal(More)
BACKGROUND Autonomic dysfunctions occur during but also in between seizures. During seizures, the direct involvement of central autonomic control centers cause specific changes in heart rate and respiration. The pathophysiology of autonomic dysfunctions that are observed in the interictal period is more difficult to explain. These alterations are most(More)
Epileptic seizures are typically related to autonomic dysfunction. During seizures, the cardiac and respiratory mechanisms are deeply affected. This effect of epilepsy can also occur a few seconds before the seizure onset in the EEG. In addition, the interaction between respiration and heart rate is also expected to be affected. This study aims to determine(More)
  • 1