Cardiology | EPFL Graph Search

Cardiology () is the study of the heart. Cardiology is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease, and electrophysiology. Physicians who specialize in this field of medicine are called cardiologists, a specialty of internal medicine. Pediatric cardiologists are pediatricians who specialize in cardiology. Physicians who specialize in cardiac surgery are called cardiothoracic surgeons or cardiac surgeons, a specialty of general surgery. Specializations All cardiologists in the branch of medicine study the disorders of the heart, but the study of adult and child heart disorders each require different training pathways. Therefore, an adult cardiologist (often simply called "cardiologist") is inadequately trained to take care of children, and pediatric cardiologists are not trained to treat

Myocardial motion and deformation analysis from echocardiograms

Michael Sühling

Echocardiography is a widely used imaging technique to examine myocardial function in patients with known or suspected heart disease. The analysis of ventricular wall motion and deformation, in particular, allows to assess the extent of myocardial ischemia and infarction. In clinical practice, the analysis mainly relies on visual inspection or manual measurements by experienced cardiologists. Manual methods are tedious and time-consuming, and visual assessment leads to qualitative and subjective diagnoses that suffer from considerable inter- and intraobserver variability. Automating the analysis of echocardiographic images is therefore highly desirable but also challenging because of the low image quality and the high amount of speckle noise. In this thesis, we propose a framework for robust and quantitative analysis of echocardiographic sequences. We make the following key contributions: Motion and Deformation Analysis—We propose a novel optical-flow-based algorithm to estimate ventricular wall motion from B-mode echocardiograms. To account for typical heart motions such as contraction/expansion and shear, we use a local affine model for the velocity in space and time. An attractive feature of the affine motion model is that it gives also access to local strain rate parameters that describe local myocardial deformation such as wall thickening. The motion parameters are estimated in the least-squares sense within a sliding spatio-temporal B-spline window. The estimation of large motions is made possible through the use of a coarse-to-fine multi-scale strategy, which also adds robustness to the method. Computational Efficiency—We introduce the notion of multiresolution moment filters, a novel filtering scheme to compute local weighted geometric moments efficiently at dyadic scales by using a wavelet-like algorithm. Beyond their application in motion analysis, we demonstrate their usefulness for image denoising and feature extraction. Multi-Modality—We extend the proposed motion analysis algorithm by integrating directional, Doppler-based velocity measurements. The exploitation of two ultrasound modalities, i.e., B-mode and tissue Doppler, renders the method more accurate and robust. Visualization—We display diagnostically meaningful motion data inside a user-defined region of interest that is tracked in time. Myocardial inward and outward motion is visualized by color coding the radial motion component with respect to the ventricular center. Two-dimensional strain rate information is superimposed in the form of deforming ellipses. The display allows a more intuitive and simplified identification of regions with abnormal motion patterns. Validation—The proposed method is validated on 1) synthetic data, 2) real ultrasound phantom data, and 3) clinical echocardiograms. A large-scale validation study that includes 114 patients confirms its ability to detect and quantify wall motion abnormalities.

EPFL2004

Multiscale Motion Mapping—A Novel Computer Vision Technique for Quantitative, Objective Echocardiographic Motion Measurement Independent of Doppler: First Clinical Description and Validation

Muthuvel Arigovindan, Michael Sühling, Michaël Unser

Background—Objective, quantitative, segmental noninvasive/bedside measurement of cardiac motion is highly desirable in cardiovascular medicine, but current technology suffers from significant drawbacks, such as subjectivity of conventional echocardiographic reading, angle dependence of tissue Doppler measurements, radiation exposure by computer tomography, and infrastructure requirements in MRI. We hypothesized that computer vision technology could represent a powerful new paradigm for quantification in echocardiography. Methods and Results—We present multiscale motion mapping, a novel computer vision technology that is based on mathematical image processing and that exploits echocardiographic information in a fashion similar to the human visual system. It allows Doppler- and border-independent determination of motion and deformation in echocardiograms at arbitrary locations. Correctness of the measurements was documented in synthetic echocardiograms and phantom experiments. Exploratory case studies demonstrated its usefulness in a series of complex motion analyses that included abnormal septal motion and analysis of myocardial twisting. Clinical applicability was shown in a consecutive series of echocardiograms, in which good feasibility, good correlation with expert rating, and good intraobserver and interobserver concordance were documented. Separate assessment of 2D displacement and deformation at the same location was successfully applied to elucidate paradoxical septal motion, a common clinical problem. Conclusions—This is the first clinical report of multiscale motion mapping, a novel approach to echocardiographic motion quantification. For the first time, full 2D echocardiographic assessment of both motion and deformation is shown to be feasible. Overcoming current limitations, this computer vision-based technique opens a new door to objective analysis of complex heart motion.

AHA2004

Measuring the T Wave of the Electrocardiogram; The How and Why

The genesis of the T wave of the electrocardiogram is discussed on the basis of a biophysical model, derived from the underlying electrophysiology. This model is used to scrutinize the commonly-assumed significance of the individual features of this waveform. As is shown, the last word is yet to be said about this topic.