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Acute or sustained stretch of cardiac tissue is known to play a key role in arrhythmogenesis. Using a fluorescence approach, we designed a system measuring calcium transients and transmembrane potential changes in monolayers of cultured cardiomyocytes under uniaxial elongation and electrical stimulation. Cardiac myocytes are seeded on a rectangular PDMS template held and stretched by a motorized linear...
Coarctation of the aorta is an obstruction of the aorta and is usually associated with other concomitant cardiovascular abnormalities especially with bicuspid aortic valve stenosis. The objectives of this study are, (1) to investigate the effects of coarctation on the hemodynamics in the aorta to gain a better understanding of the cause of certain post-surgical coarctation problems, (2) to develop...
This paper is concerned with computational modeling of a severe congenital defect called Hypoplastic left heart syndrome (HLHS) that is the most common cardiac malformation with the highest likelihood of deaths in newborns. A lumped parameter model of the HLHS circulation has been developed to study the hemodynamic variables in the various sections of the cardio-pulmonary circulation system. We applied...
A new index to assess left ventricular (LV) function in patients implanted with continuous flow left-ventricular assist devices (LVADs) is proposed. Derived from the pump flow signal, this index is defined as the coefficient (k) of the semiloga-rithmic relationship between “pseudo-ejection” fraction (pEF) and the volume discharged by the pump in diastole, (V d). pEF is defined as the ratio of the...
Fluorescence imaging of transmembrane voltage-sensitive dyes is used to study electrical activation in cardiac tissue. However, fluorescence signals typically have a low signal to noise ratio that can be contaminated with motion artifacts. We describe an alternative processing approach for fluoresced transmembrane potentials (fTmps) using the wavelet multiresolution analysis. We show that fTmp signals...
Ventricular fibrillation (VF) occurs due to disorganized electrical activity in the ventricles. This leads to rapid uncoordinated contractions of the ventricles and sudden cardiac death if not treated within minutes of its occurrence. The mechanism of VF initiation and maintenance is still elusive, however the mother rotor and multiple wavelet theories attempt to explain the mechanism behind this...
Brugada syndrome (BrS) causes sudden death in patients with structurally normal hearts. Manifestation of BrS in the ECG is dynamic and most patients do not show unequivocal signs of the syndrome during ECG screening. Electrograms (EGMs) of BrS patients show conduction delay and fractionation at the right ventricular outflow tract area (RVOT) and thus could be used for diagnosis, but their recording...
Implantable cardiac devices such as artificial pacemakers deliver therapies according to the timing information from the heart. Such devices work under the assumptions of perfect sensing, which are: (a) the pacemaker leads remain in place, and (b) the pacing therapy in one chamber (e.g. atrium) is insulated from the other chambers (e.g. ventricles). But there are common cases which violate these assumptions...
Computational modeling in electrocardiography often requires the examination of cardiac forward and inverse problems in order to non-invasively analyze physiological events that are otherwise inaccessible or unethical to explore. The study of these models can be performed in the open-source SCIRun problem solving environment developed at the Center for Integrative Biomedical Computing (CIBC). A new...
The TASER® Conducted Electrical Weapon (CEW) is used by law enforcement agencies about 900 times per day worldwide and has been shown to reduce suspect and officer injuries by about 65%. However, since a CEW delivers rapid electrical pulses through injected probes, the risk of inducing ventricular fibrillation (VF) has been considered. Animal studies have shown that the tip of the probe must come...
Due to improved reliability and reduced risk of thromboembolic events, continuous flow left ventricular assist devices are being used more commonly as a long term treatment for end-stage heart failure. As more and more patients with these devices are leaving the hospital, a reliable control system is needed that can adjust pump support in response to changes in physiologic demand. An inlet pressure...
Cell behavior during endocardial to mesenchymal transition (EMT) was simulated using the cellular Potts formalism in Compucell 3D. The processes of loss of endocardial cohesion and invasion into the extracellular matrix (ECM) were stimulated by changing surface energy parameters. The simulations match in vitro results which suggest that endocardial motility on the surface of collagen gel can be induced...
Tagged magnetic resonance imaging (MRI) has the ability to directly and non-invasively alter tissue magnetization and produce tags on the deforming tissue [1], [2]. Since its development, the Spatial Modulation of Magnetization (SPAMM) [2] tagging pulse sequence has been widely available and is the most commonly used technique for producing sinusoidal tag patterns. However, SPAMM suffers from tag...
The arterial baroreflex stabilizes arterial pressure by modulating the mechanical properties of cardiovascular system. We previously demonstrated that the baroreflex impairment makes the circulatory system extremely sensitive to volume overload and predisposes to pulmonary edema irrespective of left ventricular systolic function. To overcome the volume intolerance, we developed an artificial baroreflex...
To what extent is Empirical Mode Decomposition (EMD) able to differentiate the embedded components of a cardio-respiratory (CR) signal? We intend to answer this question by providing a tool which compares the performances of the original EMD algorithm with those of a noise-assisted version (CEEMD) on simulated CR signals, depending on the frequency and amplitude ratios between their respiratory and...
Several risk score models are available in literature to predict death/myocardial infarction event for coronary artery disease (CAD) patients, within a short period of time. However, the choice of the most adequate model is not straightforward since there might not be a consensus about the best model to use in clinical practice Moreover, individually, these models present some weaknesses, such as...
State-of-the-Art disease management for Congestive Heart Failure (CHF) patients is still based on easy-to-acquire measures such as heart rate (HR), weight and blood pressure (BP). However, these measures respond late to changes of the patient health status and provide limited information to personalize and adapt medication therapy. This paper describes our concept called “Cardiac Status Assessment”...
Chronic diseases are currently recognized as one of the leading causes of mortality and morbidity worldwide. On top of this, these diseases represent a major burden for the healthcare systems in terms of costs and resources, which is driving them to define and adopt novel programs for prevention and chronic disease management. Still, many aspects of the processes of care and follow up of these patients...
HeartCycle is a large-scale EU integrated project aiming to provide a complete disease management solution for cardiovascular disease patients, with emphasis on Heart Failure (HF) and Coronary Artery Disease (CAD) patients. The project develops innovative technologies and services to facilitate remote management of patients at home and motivate them to be compliant to treatment regimes and to adopt...
This paper describes an elasticity sensing system for left ventricle of small laboratory animal. We first show the basic concept of the proposed method, where a ring shaped specimen is dilated by a balloon type probe using a pressure based control, and the elasticity of the specimen is estimated by using the stress and strain information. We introduce a dual cylinder model for approximating the strengths...
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