Abstract：
:Both invasive left-ventricular pressure measurements and non-invasive colour M-mode echographic measurements have shown the existence of intraventricular pressure gradients (IVPGs) during early filling. The mechanisms responsible for these IVPG cannot be completely explained by the experiments. Therefore a one-dimensional numerical model is developed and validated. The model describes filling (both velocities and pressures) along a left ventricular (LV) base-apex axis. Blood-wall interaction in the left ventricle with moving boundaries is taken into account. The computational results for a canine heart indicate that the observed IVPGs during filling are the consequence of a complex interaction between, on the one hand, pressure waves travelling in the LV and, on the other hand, LV geometry, relaxation and compliance. The computational results indicate the pressure dependency of wavespeed (0.77-1.90 m-1 s) for different mean intraventricular pressures (0.88-5.00 mmHg) and IVPGs up to 2 mmHg, independent of the ratio of end systolic volume and equilibrium volume. Increasing relaxation rate not only decreases minimum basal pressure (2.8 instead of 3.6 mmHg) but also has a strong influence on the time delay between the minimum basal and apical pressures (14 ms instead of 49 ms). The results sustain the hypothesis that pressure-wave propagation determines IVPGs and that IVPGs are no proof of elastic recoil.
journal_name
Med Biol Eng Computjournal_title
Medical & biological engineering & computingauthors
Verdonck P,Vierendeels J,Riemslagh K,Dick Edoi
10.1007/BF02513338keywords:
subject
Has Abstractpub_date
1999-07-01 00:00:00pages
511-6issue
4eissn
0140-0118issn
1741-0444journal_volume
37pub_type
杂志文章abstract：:To study the effects of the geometrical characteristics of a framing coil on aneurysm thromboembolization efficacy, the hemodynamics in lateral aneurysms filled with coils having a different shape, orientation, and thickness were analyzed using computational fluid dynamics. The aneurysms packed with vortex and cage-sh...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-013-1073-2
更新日期：2013-09-01 00:00:00
abstract：:Deep brain stimulation (DBS) surgery is extensively used in the treatment of movement disorders. Nevertheless, methods to evaluate the clinical response during intraoperative stimulation tests to identify the optimal position for the implantation of the chronic DBS lead remain subjective. In this paper, we describe a ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-016-1559-9
更新日期：2017-05-01 00:00:00
abstract：:A method for accurately finding cardiac bidomain conductivity parameters is a crucial part of efforts to study and understand the electrical functioning of the heart. The bidomain model considers current flowing along (longitudinal) and across (transverse) sheets of cardiac fibres, as well as between these sheets (nor...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-013-1101-2
更新日期：2013-12-01 00:00:00
abstract：:Parkinson's disease (PD) is a neurodegenerative disease of the central nervous system that results from the degeneration of dopaminergic neurons in the substantia nigra. Abnormal gait begins in the early stage and becomes severe as the disease progresses; therefore, the assessment of gait becomes an important issue in...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-015-1335-2
更新日期：2016-03-01 00:00:00
abstract：:A technique to obtain the spacing distribution of macro- and microstructures of hypercholestrolemic liver, lymphoidlucosed liver, rhinosporidium of man and ethmoidal tumour of bovine is presented. The method uses signal processing of spatially averaged spectra of ultrasonic backscattering from tissues in the frequency...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02442608
更新日期：1990-11-01 00:00:00
abstract：:The understanding of cardiac arrhythmia under genetic mutations has grown in interest among researchers. Previous studies focused on the effect of the D172N mutation on electrophysiological behavior. In this study, we analyzed not only the electrophysiological activity but also the mechanical responses during normal s...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-020-02124-w
更新日期：2020-05-01 00:00:00
abstract：:Implantable cardioverter defibrillators (ICDs) can store intracardiac electrograms (EGMs) in sinus rhythm (SR), at the onset of spontaneous ventricular tachyarrhythmias (VT) or during their course. This allows the investigation of unknown features of the heart electrical activity associated with different cardiac rhyt...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-005-0014-0
更新日期：2006-03-01 00:00:00
abstract：:To make picture archiving and communication systems (PACS) a practical reality for small-scale structures, it appears necessary to build a network that integrates and optimises production management, analysis and storage of images, and to include the ability to communicate with other similar remote structures. To solv...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02458046
更新日期：1993-05-01 00:00:00
abstract：:A biomechanical analysis of the constant peak displacement and constant peak force methods of cardiopulmonary resuscitation (CPR) has revealed that optimal CC performance strongly depends on back support stiffness, CC rate, and the thoracic stiffness of the patient being resuscitated. Clinically the results presented ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-012-0963-z
更新日期：2012-12-01 00:00:00
abstract：:The present study describes a new methodological approach which allows the separate analysis and quantitative determination of the viscous and elastic components of human hair using a computerised experimental system. In a first series of experiments subsequent to the estimation of the cross-sectional surface area of ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02446198
更新日期：1992-01-01 00:00:00
abstract：:Photoplethysmography imaging (PPGI) for non-contact monitoring of preterm infants in the neonatal intensive care unit (NICU) is a promising technology, as it could reduce medical adhesive-related skin injuries and associated complications. For practical implementations of PPGI, a region of interest has to be detected ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-020-02251-4
更新日期：2020-12-01 00:00:00
abstract：:This article presents model predictive controllers (MPCs) and multi-parametric model-based controllers for delivery of anaesthetic agents. The MPC can take into account constraints on drug delivery rates and state of the patient but requires solving an optimization problem at regular time intervals. The multi-parametr...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-010-0604-3
更新日期：2010-06-01 00:00:00
abstract：:It is proposed that myo-electric signals can be used to augment conventional speech-recognition systems to improve their performance under acoustically noisy conditions (e.g. in an aircraft cockpit). A preliminary study is performed to ascertain the presence of speech information within myo-electric signals from facia...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345373
更新日期：2001-07-01 00:00:00
abstract：:Computer-based simulations of human hip joints generally include investigating contacts happening among soft or hard tissues during hip movement. In many cases, hip movement is approximated as rotation about an estimated hip center. In this paper, we investigate the effect of different methods used for estimating hip ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-012-0873-0
更新日期：2012-06-01 00:00:00
abstract：:The development of an active implantable device for measuring electrocardiogram (ECG) is presented. The study is a part of a project which aims at developing implantable ECG instrumentation with wireless data and power transfer ( http://www.ele.tut.fi/tule ). The developed implant presented here has all the measuremen...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章,评审
doi：10.1007/s11517-007-0264-0
更新日期：2007-12-01 00:00:00
abstract：:The Chinese herb radix Salviae miltiorrhizae (RSM) is used in traditional Chinese medicine as a treatment for cardiovascular and cerebrovascular diseases. Several components of the plant extract from salvia mitorrhiza bunge have been determined previously, one of which is protocatechuic acid (PAC). It has been found, ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345308
更新日期：2002-11-01 00:00:00
abstract：:An algorithm for determining the frequency and propagation time of the gastric slow wave has been designed for integration into a demand gastric pacing system. The algorithm analyses the serosal activity in both the time and frequency domains, and the results are compared to produce a conclusion only when the values a...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02344688
更新日期：2000-01-01 00:00:00
abstract：:Chronic obstructive pulmonary disease (COPD) is characterized by expiratory airflow limitation, but current diagnostic criteria only consider flow till the first second and are therefore strongly debated. We aimed to develop a data-based individualized model for flow decline and to explore the relationship between mod...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-014-1202-6
更新日期：2014-12-01 00:00:00
abstract：:We introduce a novel method for an automatic classification of subjects to those with or without neuromuscular disorders. This method is based on multiscale entropy of recorded surface electromyograms (sEMGs) and support vector classification. The method was evaluated on a single-channel experimental sEMGs recorded fr...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-010-0629-7
更新日期：2010-08-01 00:00:00
abstract：:Musculoskeletal models have been developed to estimate internal loading on the human skeleton, which cannot directly be measured in vivo, from external measurements like kinematics and external forces. Such models of the shoulder and upper extremity have been used for a variety of purposes, ranging from understanding ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章,评审
doi：10.1007/s11517-013-1099-5
更新日期：2013-09-01 00:00:00
abstract：:The main constituent of an ultrasound contrast agent (UCA) is gas-filled microbubbles. An average UCA contains billions per ml. These microbubbles are excellent ultrasound scatterers due to their high compressibility. In an ultrasound field they act as resonant systems, resulting in harmonic energy in the backscattere...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-009-0497-1
更新日期：2009-08-01 00:00:00
abstract：:High-intensity noises are a health hazard for industrial workers, and hearing protection is necessary to prevent hearing loss. Passive methods, such as ear muffs, are ineffective against low-frequency noise. Moreover, many hearing-impaired workers must wear hearing aids to enable communication at their workplace, and ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02430951
更新日期：2005-11-01 00:00:00
abstract：:It is acknowledged that the first heart sound S1 consists of two major, high-frequency components M1 and T1, corresponding, respectively, to the vibrations of the mitral and tricuspid valves and their surrounding tissues following valve closure in early systole. In this study, the matching pursuit (MP) method was used...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345436
更新日期：2001-11-01 00:00:00
abstract：:In electrocardiographic imaging (ECGI), one solves the inverse problem of electrocardiography (ECG) to reconstruct equivalent cardiac sources based on the body surface potential measurements and a mathematical model of the torso. Due to attenuation and spatial smoothing within the torso, this inverse problem is ill-po...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-019-02018-6
更新日期：2019-10-01 00:00:00
abstract：:Magnetoenterography (MENG) is a new, non-invasive technique that measures gastrointestinal magnetic signals near the body surface. This study was undertaken to evaluate the temporal and spatial characteristics of the magnetic signals generated by gastric and duodenal slow wave activity. The gastrointestinal magnetic f...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02513347
更新日期：1999-09-01 00:00:00
abstract：:Remote patient monitoring should reduce mortality rates, improve care, and reduce costs. We present an overview of the available technologies for the remote monitoring of chronic obstructive pulmonary disease (COPD) patients, together with the most important medical information regarding COPD in a language that is ada...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章,评审
doi：10.1007/s11517-018-1798-z
更新日期：2018-04-01 00:00:00
abstract：:Induction coils were fabricated based on flexible printed circuit board for inductive transcutaneous power transmission. The coil had closed magnetic circuit (CMC) structure consisting of inner and outer magnetic core. The power transmission efficiency of the fabricated device was measured in the air and in vivo condi...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-012-0939-z
更新日期：2012-09-01 00:00:00
abstract：:Classification of cancerous genes from microarray data is an important research area in bioinformatics. Large amount of microarray data are available, but it is very costly to label them. This paper proposes an active learning model, a semi-supervised classification approach, to label the microarray data using which p...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-020-02238-1
更新日期：2020-10-01 00:00:00
abstract：:This study examined the electroencephalogram functional connectivity (coherence) and effective connectivity (flow of information) of selected brain regions during three different attentive states: awake, meditation and drowsiness. For the estimation of functional connectivity (coherence), Welch and minimum variance di...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-015-1272-0
更新日期：2015-07-01 00:00:00
abstract：:Results of self-consistent analyses of cells show the possibility of temperature increases at membranes in response to a single nanosecond, high-voltage pulse, at least over small sections of the membrane. Molecular Dynamics simulations indicate that such a temperature increase could facilitate poration, which is one ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-011-0745-z
更新日期：2011-06-01 00:00:00
