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In this manuscript we present an overview of novel signal processing techniques developed by our group to reduce scoring time in the assessment of the severity of sleep-related breathing disorders in heart failure patients and to detect sleep/wake fluctuations during periodic breathing. Besides describing these methods, we present the results of validation experiments. Our work shows that novel signal...
Tissue engineering of vascular grafts still presents several shortcomings. Aiming to vascular regeneration, we developed a biomimetic multilayered scaffold with a middle pivotal collagen lamina between two functionalized layers of poly-L-lactide by means of electrospinning technique, with oriented drug-delivery capacity for the differentiation of human mesenchymal stem cells seeded therein. Applying...
Progress toward understanding the thermo-mechanical behavior of isolated cardiac muscle, excised from either healthy or diseased heart, is contingent on being able to measure simultaneously the stress (force per cross-sectional area) and heat production. Determination of dynamic modulus (dynamic stiffness times muscle length per cross-sectional area) sheds further light on the behavior of the force-and...
We have developed a novel automated drug delivery system for simultaneous control of systemic arterial pressure (AP), cardiac output (CO), and left atrial pressure (PLA) in acute heart failure. The circulatory equilibrium framework we established previously discloses that AP, CO, and PLA are determined by equilibrium of the mechanical properties of the circulation, i.e. pumping ability of the left...
In this paper, we present two additions to the SFLC algorithm in order to improve the beat by beat estimation of fiducial points (B and X) and the maximum value of the derivative in impedance cardiography signal: addition of a reference input and scanning each beat more than once. On data synthesized from real ICG which exhibits beat by beat changes and baseline variations, we used statistical measures...
Experiments in vitro on a Microelectrode Array (MEA) platform show that electrical stimulation can provoke the generation of spiral waves in cardiac tissue. Nevertheless, the conditions leading to this artificial fibrillation state remain unclear. In order to have a better understanding of this phenomenon, a numerical simulation study has been conducted. The results obtained with a two-dimensional...
In our extended Guyton's model, the ability of heart to pump blood is characterized by a cardiac output curve and the ability of vasculature to pool blood by a venous return surface. These intersect in a three-dimensional coordinate system at the operating right atrial pressure, left atrial pressure, and cardiac output. The baseline cardiac output curve and venous return surface and their changes...
A prototype of a ECG ambulatory system for long term monitoring of ST segment of 3 leads, low power, portability and data storage in solid state memory cards has been developed. The solution presented is based in a mobile embedded architecture of a portable entertainment device used as a tool for storage and processing of bioelectric signals, and a mid-range RISC microcontroller, PIC 16F877, which...
Annulus manual segmentation is an important tool for the study of valve anatomy and physiology, for the four main valves of the heart (mitral, tricuspid, aortic and pulmonary). In this paper we review two traditional manual segmentation approaches: slice-by-slice and interpolating a sparse set of landmarks with a spline curve. We propose a new Spline Tool for the open source software platform Seg3D,...
The integration of mapping techniques with suitable methods for the characterization and visualization of propagation patterns may enhance the targeting of critical arrhythmic areas, thus optimizing the ablative treatment of atrial arrhythmias. In this study, we tested the feasibility of an innovative approach for the automatic determination of activation and velocity maps from sparse data as provided...
The goal of this study is to optimize the transfer of acoustic energy deep in the body. In order to find suitable acoustic paths for the energy transfer to be efficient, we propose a model of ultrasound propagation that takes into account a realistic geometry of the tissue layers inside the human body. The data from the Visible Human Project is used to identify the tissues between the transducer array...
Hydrodynamic valve performance is usually evaluated by effective orifice area (EOA), geometric orifice area (GOA) and transvalvular pressure gradients (PG). Magnetic resonance imaging (MRI) is a very efficient tool for assessing these parameters. In this study, we evaluated a silicone rubber trileaflet valve using MRI. EOA, GOA and PG were evaluated under steady (12 l/min - 20 l/min) and pulsatile...
Our group has been investigating the use of Shearwave Dispersion Ultrasound Vibrometry (SDUV) for quantifying viscoelasticity of the myocardium. The primary aim of this study is the design and testing of viscoelastic materials suitable for validation of the Lamb wave model in the heart. The Lamb wave SDUV method was used to measure shear wave velocity dispersion of gelatin and urethane rubber plates...
An important goal in clinical cardiology is the non-invasive quantification of regional cardiac deformation. While many methods have been proposed for the estimation of 3D left ventricular deformation and strains derived from 4D ultrasound, currently there is a lack of in vivo clinical validation of these algorithms on humans. In this paper, we describe the experiments used in validating cardiac deformation...
Wireless physiological/neurological monitoring in virtual reality (VR) offers a unique opportunity for unobtrusively quantifying human responses to precisely controlled and readily modulated VR representations of health care environments. Here we present such a wireless, light-weight head-mounted system for measuring electrooculogram (EOG) and electroencephalogram (EEG) activity in human subjects...
The partially separable function (PSF) model has been successfully used to reconstruct cardiac MR images with high spatiotemporal resolution from sparsely sampled (k,t)-space data. However, the underlying model fitting problem is often ill-conditioned due to temporal undersampling, and image artifacts can result if reconstruction is based solely on the data consistency constraints. This paper proposes...
Personalized health devices are the novel paradigm to reduce healthcare costs and to improve the quality of health services. At the same time, health interventions and promotion of self behaviors generate benefits to healthcare and allow citizens to be more involved in their own health management. This paper describes the process followed in HeartCycle project to design education and coaching services...
We present a new type of non-contact sensor for use in ambulatory cardiac monitoring. The sensor operation is based on a microwave Doppler technique; however, instead of detecting the heart activity from a distance, the sensor is placed on the patient's chest over the clothing. The microwave sensor directly measures heart movement rather than electrical activity, and is thus complementary to ECG....
The cardiac magnetic resonance (CMR) images from a group of patients with myocardial scars and implanted cardioverter-defibrillator (ICD) are divided into a group with low risk of arrhythmias (late incidents) and a group with high risk of arrhythmias (early incidents). Several hundred quantitative features describing sizes, statistics and textures of the segmented and defined areas of the images are...
Based on some reported clinical data, we attempt to apply the allometric law for evaluating the probability of ventricular fibrillation when electrocardiographic ST-segment deviations are determined. The deviation is measured in millimeters at the standard calibration of 1mV = 10mm and the probability in percent. Using the equation VFP = δ + β (ST) in log-log representation, the fitting procedure...
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