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The pressure-volume relationship of the heart was first reported more than a century ago. It was not widely accepted, however, until the mid-1970s. The pressure-volume diagram became a central theme of cardiac mechanics once it was shown to be a good representation of ventricular mechanics. Early in 1980s, the introduction of the ventricular interaction with afterload using effective arterial elastance...
Sleep science and respiratory engineering as medical subspecialties and research areas grew up side-by-side with biomedical engineering. The formation of EMBS in the 1950's and the discovery of REM sleep in the 1950's led to parallel development and interaction of sleep and biomedical engineering in diagnostics and therapeutics.
Pulse wave velocity (PWV) is a marker of arterial stiffness and may permit continuous, non-invasive, and cuff-less monitoring of blood pressure. Here, robust PWV estimation was sought by application of system identification to proximal and distal arterial waveforms. In this approach, the system that optimally couples the proximal waveform to the distal waveform is identified, and the time delay of...
When recording the pressure oscillations of a seated subject two distinct effects are assessed, ample vibrations due to the person's movement, and periodic oscillations of small amplitude due to cardiopulmonary activity, expressed by the ballistocardiogram (BCG). Embedding a pressure sensor in a chair's back or seat allows unobtrusive monitoring of the BCG. However, inconspicuously acquired signals...
In this study we propose a pipeline for simulation of late gadolinium enhancement images. We used a modified version of the XCAT phantom to improve simulation realism. Modifications included the modeling of trabeculae and papillary muscles, and the increase of sublabels to resemble tissue intensity variability. Magnetic properties for each body tissue were sampled in three settings: from Gaussian...
A generic cardiac ionic model employing membrane currents based on two-gate Hodgkin-Huxley kinetics is presented. Its generic nature allows it to accurately reproduce action potential waveforms in heterogeneous cardiac tissue by optimizing parameters governing ion channel kinetics and magnitudes. The model allows a user-defined number of voltage and time-dependent ion currents to be incorporated,...
Experimental action potential (AP) recordings in isolated ventricular myoctes display significant temporal beat-to-beat variability in morphology and duration. Furthermore, significant cell-to-cell differences in AP also exist even for isolated cells originating from the same region of the same heart. However, current mathematical models of ventricular AP fail to replicate the temporal and cell-to-cell...
The assessment of the autonomic cardiovascular regulation provides important diagnostic and prognostic information. The aim of this study was to investigate the alterations of this autonomic regulation in the progress of a normal pregnancy and in several pregnancy disorders associated with hypertension, especially pre-eclampsia, applying the method of Joint Symbolic Dynamics (JSD). The JSD reveals...
In this work we propose a novel approach for filtering noise-affected electrocardiogram (ECG) signals. The proposed method, mainly based on signal approximation by means of linear segments, has been applied for R-peaks recognition and has been compared with both cardiologists' manual marking and the automatic Laguna's method. The obtained results show that when compared to the Laguna's method the...
Anatomically realistic and biophysically based computational models of the heart have provided valuable insights into cardiac function in health and disease. Nevertheless, these models typically use a “black-box” approach to describe the cellular level processes that underlie the heart beat. We are developing techniques to stochastically generate three-dimensional models of mammalian ventricular myocytes...
The Real-time Experiment Interface (RTXI) is a fast and versatile real-time biological experimentation system based on Real-Time Linux. RTXI is open source and free, can be used with an extensive range of experimentation hardware, and can be run on Linux or Windows computers (when using the Live CD). RTXI is currently used extensively for two experiment types: dynamic patch clamp and closed-loop stimulation...
A gaming platform has been used to implement a Home Automated Telemanagement (HAT) system for chronic disease management in the patient's home. The system questions patients with congestive heart failure (CHF) to monitor symptoms, weight changes, and quality of life while educating the patient on their disease. The system is designed to run on the Nintendo Wii videogame console using an active internet...
Heart Beat Rate calculation has traditionally been conducted using specialized hardware most commonly in the form of pulse oximeters or Electrocardiogram devices. Even though these methods offer high reliability, they require the users to have special sensor to measure their heart rate. In this paper we propose a system capable of estimating the heart beat rate using just a camera from a commercially...
Left-ventricular shape is an important determinant of regional wall mechanics during passive filling. To examine the influence of left-ventricular shape for the ejection phase, the distribution of active fiber stress at the beginning of ejection was calculated in a finite element study. Hereto, finite element models were constructed with varying left-ventricular shapes, ranging from an elongated ellipsoid...
This paper investigates the application of a multi-loop PID controller in an automated treadmill exercise machine. The approach is to design a computer-controlled treadmill control system for the regulation of heart rate (HR) during treadmill exercise. A single-input and multiple-output (SIMO) controller was implemented to fast track a given heart rate profile in treadmill exercise. Two separate single-input...
Respiratory sinus arrhythmia (RSA) is largely mediated by the autonomic nervous system through its modulating influence on the heartbeat. We propose an algorithm for quantifying instantaneous RSA as applied to heart beat interval and respiratory recordings under dynamic respiration conditions. The blood volume pressure derived heart beat series (pulse intervals, PI) are modeled as an inverse gaussian...
Heartbeat and respiration are fundamental vital signs used for estimation of patient's status. In this study, we have proposed a simple method to monitor the heartbeat and respiration based on displacements of human body which occur due to periodic heartbeat and breathing. The proposed system consists of an aircushion, pressure sensing hardware and extraction algorithm. The displacements of subject...
In neurophysiological and pharmaceutical research, parallel and individual access to a dense population of in-vitro cultured neurons is a key feature for analyzing networks of neurons. This paper presents a 0.18μm CMOS chip containing a dense array of micro-nail electrodes, a 128 × 128 sensor/actuator matrix with in-situ differential amplification circuits, pico-Ampere current stimulation, and impedance...
Role of dual AV nodal pathway physiology in the atrioventricular nodal (AVN) conduction during atrial arrhythmias remains unclear. By using His electrogram alternans (HEA), we have developed a functional model of the atrioventricular conduction that incorporates the dual AV nodal pathway physiology. Experiments performed on 5 rabbit atrial-AVN preparations were used to develop and test the presented...
A considerable number of patients in weaning process have problems to keep spontaneous breathing during the trial and after it. This study proposes to extract characteristic parameters of the RR series and respiratory flow signal according to the patients' condition in weaning test. Three groups of patients have been considered: 93 patients with successful trials (group S), 40 patients that failed...
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