Papers by Maria G Signorini
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society Volume 13: 1991
In the present paper we introduce the method of analysis of power spectrum for the heart rate var... more In the present paper we introduce the method of analysis of power spectrum for the heart rate variability (HRV) signal, in normal healthy subjects, undergoing various procedures of physical and psychophysical stress. The spectral parameters obtained constitute a quantitative marker which describes the sympatho-vagal balance elicited in the control of heart rate and other cardiovascular signals. Such an approach is considered important for the evaluation of the effect of different stressors in human cardiovascular physiology and the related pathology.
Physiological Measurement, 2012
Blood pressure values are characterized by marked fluctuations occurring not only within a 24-hou... more Blood pressure values are characterized by marked fluctuations occurring not only within a 24-hour period, but also on a day-today and even visit-to-visit basis. Such blood pressure fluctuation was once considered 'background noise' or a randomly occurring phenomenon; however, recently it is widely accepted that these variations are the result of complex interactions between extrinsic environmental and behavioral factors and intrinsic cardiovascular regulatory mechanisms. Although adverse cardiovascular consequences of hypertension largely depend on absolute blood pressure values, variations in blood pressure also have predictive value for cardiovascular events. Post-hoc analyses of large intervention trials in hypertension have shown that within-patient visit-to-visit blood pressure variation is strongly prognostic for cardiovascular morbidity and mortality, especially in high-risk patients, suggesting that antihypertensive treatment should be targeted not only towards reducing mean blood pressure levels but also to stabilizing blood pressure variability.
It is well known that the coordination among several subsystems in newborns is effectively changi... more It is well known that the coordination among several subsystems in newborns is effectively changing as a function of behavioral states. For this reason, sleep state characterization is an essential procedure in neonatal monitoring. Despite its importance, methodologies assessing sleep states are discrete in time and usually based on visual inspection. In this work, we validate a point process framework on a population of 113 full-term infants with the aim of providing continuous sleep state characterization over time. After determining a suitable probability density distribution to best fit the neonatal RR series, we compare traditional heart rate variability (HRV) parameters with the point process-extracted sets of time and frequency domain instantaneous measures in order to validate the proposed framework. Our results provide insights into the point process ability to capture HRV dynamics with a high degree of reliability, thus providing evidence that our framework might be employ...
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
This paper presents the analysis of the autonomic nervous system (ANS) control and cardiac barore... more This paper presents the analysis of the autonomic nervous system (ANS) control and cardiac baroreflex sensitivity in patients undergoing general anesthesia for major surgery, with the goal of evaluating the effects of anesthesia bolus induction with propofol on autonomic control of heart rate (HR) and arterial blood pressure (ABP). The increase in baroreflex gain in the LF band observed through two different methods hints at the fact that the baroreflex may increase heart period (HP) following a transient ABP decrease, but its response displays a larger amplitude, to compensate for the blunting of the sympathetic action on heart rate and vascular resistance.
Proceedings of the International Conference on Environmental Modelling and Software Society (iEMSs)–14-17 June 2004 University of Osnabruck, 2004
Abstract: We present a Cellular Automata based model for the simulation of the dynamics of plant ... more Abstract: We present a Cellular Automata based model for the simulation of the dynamics of plant populations. The evolution of a plant population in a given area mainly depends on the resources available on the territory (in turn influenced by other factors like sunlight, rain, temperature, and so on) and how different individuals (plants) compete for them.
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439)
Simulations of the activity of a brain cortex slice have been carried out in different conditions... more Simulations of the activity of a brain cortex slice have been carried out in different conditions that mimic physiological and pathological situations of the tissue. The assumption is the coupling of the excitation dynamics of the single cells drives the electrocortical activity. Cellular Automata (CA) has implemented a local rule, which has been taken from a continuous model of cortical
In this paper, new parameters based on the Phase Rectified Signal Average (PRSA) of the Fetal Hea... more In this paper, new parameters based on the Phase Rectified Signal Average (PRSA) of the Fetal Heart Rate (FHR) signal are introduced to assess fetal wellbeing. They are defined as the positive and negative slopes of the PRSA curve, namely Acceleration Phase Rectified Slope (APRS) and Deceleration Phase Rectified Slope (DPRS), depending on the sign of the slope. The parameters were computed on FHR time series recorded from 59 healthy and 61 Intra Uterine Growth Restricted (IUGR) fetuses, during CTG non-stress tests. The performance of APRS and DPRS was compared with the performance of other parameters extracted from the PRSA curve already existing in literature, and with other clinical indices that are provided by computerized cardiotocographic systems. The APRS and DPRS performed better than any other parameter considered in this study to distinguish between healthy and IUGR fetuses. We believe that these new indices might provide useful improvements of the quality of fetus early di...
Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology
ABSTRACT
Computer Methods and Programs in Biomedicine
Background and objectives: Intrauterine Growth Restriction (IUGR) is a fetal condition defined as... more Background and objectives: Intrauterine Growth Restriction (IUGR) is a fetal condition defined as the abnormal rate of fetal growth. The pathology is a documented cause of fetal and neonatal morbidity and mortality. In clinical practice, diagnosis is confirmed at birth and may only be suspected during pregnancy. Therefore, designing an accurate model for the early and prompt identification of pathology in the antepartum period is crucial in view of pregnancy management. Methods: We tested the performance of 15 machine learning techniques in discriminating healthy versus IUGR fetuses. The various models were trained with a set of 12 physiology based heart rate features extracted from a single antepartum CardioTocographic (CTG) recording. The reason for the utilization of time, frequency, and nonlinear indices is based on their standalone documented ability to describe several physiological and pathological fetal conditions. Results: We validated our approach on a database of 60 healthy and 60 IUGR fetuses. The machine learning methodology achieving the best performance was Random Forests. Specifically, we obtained a mean classification accuracy of 0.911 [0.860, 0.961 (0.95 confidence interval)] averaged over 10 test sets (10 Fold Cross Validation). Similar results were provided by Classification Trees, Logistic Regression, and Support Vector Machines. A features ranking procedure highlighted that nonlinear indices showed the highest capability to discriminate between the considered fetal conditions. Nevertheless, is the combination of features investigating CTG signal in different domains, that contributes to an increase in classification accuracy. Conclusions: We provided validation of an accurate artificially intelligence framework for the diagnosis of IUGR condition in the antepartum period. The employed physiology based heart rate features constitute an interpretable link between the machine learning results and the quantitative estimators of fetal wellbeing.
Computational and Mathematical Methods in Medicine, 2015
Objective.This study used a new method called Acceleration (or Deceleration) Phase-Rectified Slop... more Objective.This study used a new method called Acceleration (or Deceleration) Phase-Rectified Slope, APRS (or DPRS) to analyze computerized Cardiotocographic (cCTG) traces in intrauterine growth restriction (IUGR), in order to calculate acceleration- and deceleration-related fluctuations of the fetal heart rate, and to enhance the prediction of neonatal outcome.Method.Cardiotocograms from a population of 59 healthy and 61 IUGR fetuses from the 30th gestation week matched for gestational age were included. APRS and DPRS analysis was compared to the standard linear and nonlinear cCTG parameters. Statistical analysis was performed through thet-test, ANOVA test, Pearson correlation test and receiver operator characteristic (ROC) curves (p<0,05).Results.APRS and DPRS showed high performance to discriminate between Healthy and IUGR fetuses, according to gestational week. A linear correlation with the fetal pH at birth was found in IUGR. The area under the ROC curve was 0.865 for APRS an...
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
Blood pressure (BP) response to volume depletion induced by hemodialysis (HD) treatment may be im... more Blood pressure (BP) response to volume depletion induced by hemodialysis (HD) treatment may be important to understand the pathophysiology of the increased mortality in HD patients with vascular calcification. In the present study a comparison between end stage renal disease (ESRD) patients affected by peripheral vascular disease (PVD) and ESRD patients without PVD was performed. Continuous blood pressure was recorded at the beginning and at the end of HD. BP and heart rate variability (HRV) were analyzed to quantify the autonomic nervous system regulation of heart beat and peripheral resistance. PVD patients showed an increase of pulse pressure (PP) during HD, an altered autonomic peripheral control, a lower sympathetic activity, with respect to ESRD patients without PVD.
In this paper, new parameters based on the Phase Rectified Signal Average (PRSA) of the Fetal Hea... more In this paper, new parameters based on the Phase Rectified Signal Average (PRSA) of the Fetal Heart Rate (FHR) signal are introduced to assess fetal wellbeing. They are defined as the positive and negative slopes of the PRSA curve, namely Acceleration Phase Rectified Slope (APRS) and Deceleration Phase Rectified Slope (DPRS), depending on the sign of the slope. The parameters were computed on FHR time series recorded from 59 healthy and 61 Intra Uterine Growth Restricted (IUGR) fetuses, during CTG non-stress tests. The performance of APRS and DPRS was compared with the performance of other parameters extracted from the PRSA curve already existing in literature, and with other clinical indices that are provided by computerized cardiotocographic systems. The APRS and DPRS performed better than any other parameter considered in this study to distinguish between healthy and IUGR fetuses. We believe that these new indices might provide useful improvements of the quality of fetus early diagnosis.
International Journal of Bifurcation and Chaos, 1998
The cardiac conduction system may be assumed to be a network of self-excitatory pacemakers, with ... more The cardiac conduction system may be assumed to be a network of self-excitatory pacemakers, with the SinoAtrial (SA) node having the highest intrinsic rate. Subsidiary pacemakers with slower firing frequencies are located in the AtrioVentricular (AV) node and the His-Purkinje system. Under physiological conditions, the SA node is the dominant pace-maker and impulses travel from this node to the ventricle through the AV junction, which is traditionally regarded as a passive conduit. We consider the Av node as an active pace-maker and develop a model of two nonlinear coupled oscillators in order to describe the interaction between the SA and the AV node. These two nonlinear oscillators are based on a modification of the van der Pol osciallator, so that the generated waveforms resemble the action potentials of cells in the SA and the AV node respectively. A bifurcation analysis of this model is performed and the pathophysiological different kinds of heartbeat pathologies (1°, 2° (both ...
The cardiac conduction system may be assumed to be a network of self-excitatory pacemakers, with ... more The cardiac conduction system may be assumed to be a network of self-excitatory pacemakers, with the SinoAtrial (SA) node having the highest intrinsic rate. Subsidiary pacemakers with slower firing frequencies are located in the AtrioVentricular (AV) node and the His-Purkinje system. Under physiological conditions, the SA node is the dominant pace-maker and impulses travel from this node to the ventricle through the AV junction, which is traditionally regarded as a passive conduit. We consider the Av node as an active pace-maker and develop a model of two nonlinear coupled oscillators in order to describe the interaction between the SA and the AV node. These two nonlinear oscillators are based on a modification of the van der Pol osciallator, so that the generated waveforms resemble the action potentials of cells in the SA and the AV node respectively. A bifurcation analysis of this model is performed and the pathophysiological different kinds of heartbeat pathologies (1°, 2° (both Wenckebach and non-Wenckebach) and 3° AV blocks, sinus arrest, atrials bigeminy, etc.). This simple nonlinear model helps to improve the understanding of the complex phenomena involved in heart rhythm generation as well as of heart rate control and function.
... e di Tele-ecografia A. Di Lieto*, M. Campanile*, M. De Falco*, G. Magenes", MG Signorina... more ... e di Tele-ecografia A. Di Lieto*, M. Campanile*, M. De Falco*, G. Magenes", MG Signorina 'università degli Studi di Napoli Federico li ■ Dipartimento ... tnt J Gynecol Obstet 1997;57:33-7. 2. Anceschi MM, Piazze 11, Ruozi-Berretta A et a!. - Validity of short term variation (STV) in ...
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Papers by Maria G Signorini