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Blood pressure (BP) is one of the most important physiological parameters reflecting cardiovascular status of people. Continuous and non-invasive BP measurement, which can provide beat-to-beat BP information and call attention to the doctor if the patent is in danger during surgery, plays a very important role in safety control in operation and intensive care. In this paper, a novel and complete methodology...
As cardiovascular disorders have emerged as the primary cause of human mortality, quantitative modeling of cardiovascular system, including the dynamic coupling among its chemical, electrical and pulmonary mechanisms, has evoked keen interest in the recent years. The current dynamic models have little clinical relevance because they cannot be correlated with the real-time signals from a human heart...
The purpose of this paper is to analyze morphological differences in sigmoidal characteristics of baroreflex among two groups of children: highly-reactive and non-reactive. These two groups are separated based on their different autonomic nervous system responses to stressful situations. Baroreflex or baroreceptor reflex is a prompt biological reflex which is stimulated by baroreceptors, and regulated...
The study aimed to determine the potential of pulse wave velocity measurements to reflect changes in compliant cerebral arteries/arterioles in head injured patients. The approach utilizes the electrocardiogram and intracranial pressure signals to measure the wave transit time between heart and cranial cavity. Thirty five clinical records of nineteen head injured patients, with different levels of...
The Pulse Transit Time (PTT) is generally assumed to be a good surrogate measure to comfortably track blood pressure (BP) and blood pressure changes. This paper investigates PTT variations for healthy young subjects during a sequence of short-term physical exercises. PTT was measured by two different methodologies having different measurement accuracies as well as underlying assumptions: the total...
Implantation of sensors to measure hemodynamic parameters such as pulsatile pump flow and differential pressure (head) in an implantable rotary pump (IRBP) requires regular in situ calibration due to measurement drift. In addition, risks associated with sensor failure and thrombus formation makes the long-term implantation in patients problematic. In our laboratory, two stable and novel dynamical...
The pressure-dependent compliance is being paid more and more attention with the research on cardiovascular diseases, because it provides us a new perspective to understand the relation between the arterial compliance and the blood pressure. Based on previous work, the paper proposes a novel algorithm to estimate human arterial pressure-dependent compliance. The nonlinear differential equation incorporating...
The esophageal Doppler monitor (EDM) is a minimally-invasive device to measure aortic blood flow and quantify hemodynamics in patients. A modified dual-Doppler EDM, combined with pressure measurements, allows for measurement of aortic volume via the Bramwell-Hill equation. An in-vitro flow system was developed to model the cardioaortic circulation. This system consists of a pump to expel a viscous...
In this study, an innovative least-squares adaptive estimator is developed for heart fault diagnosis. The reference model of this study is the one developed by Ursino in 1998. Mitral valve function is studied in this paper based on a new method which uses invasive noisy blood pressure waveform observations of left ventricle, left atrium, and left pulmonary vein. To meet this end, an adaptive algorithm...
An approach to classify disorders in autonomic control of cardiovascular system is proposed in this paper. The target of this study is to highlight main features of malfunctions in cardiovascular system due to autonomic disorder. Collecting the data from the physionet archive, we divide patients into two groups of normal and abnormal, based on having autonomic disorder in their cardiovascular system...
A mathematical model, based on our previous pulsatile nonlinear multi-element cardiovascular model, was tested and improved to study cardiovascular response under graded exercise levels. Ten healthy subjects were studied using cycle-ergometry exercise test with constant workloads ranging from 25 Watt to 125 Watt. Breath by breath gas exchange, heart rate, cardiac output, stroke volume and blood pressure...
Total Peripheral Resistance (TPR) is the resistance of the arterial tree, defined as the ratio between the mean systemic pressure and the cardiac output. A lumped parameters model of the arterial tree with active and non linear peripheries was developed in order to show how mutual interactions between systemic and local responses characterize non-linear modulations of TPR. Numerical simulations showed...
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