Abstract:The study demonstrates that ECGI can reconstruct epicardial potentials, electrograms, and isochrones over the entire epicardial surface during the cardiac cycle. It can provide detailed information on local activation of the heart noninvasively. Its uses could include localization of cardiac electric events (eg, ectopic foci), characterization of nonuniformities of conduction, characterization of repolarization properties (eg, dispersion), and mapping of dynamically changing arrhythmias (eg, polymorphic VT) on… Show more
“…The Tikhonov regularization method 76 with CRESO-determined regularization parameter 24 is used to stabilize the inverse procedure and obtain , similar to our previous ECGI inverse computations using mesh-based BEM. 15,16,32,33,47,56,61,62,[65][66][67][68][69][70][71] Once the coefficient vector is obtained, u(x) can be computed at any location in the domain using: (5) The epicardial potential can then be calculated using: (6) Epicardial potentials are calculated using (6) on many epicardial nodes; numbers are provided for each dataset in the Results section. An epicardial potential map, reflecting the spatial distribution of potentials on the epicardial surface, is computed every millisecond during the cardiac cycle.…”
Section: Formulating the Methods Of Fundamental Solutions For Ecgimentioning
confidence: 99%
“…62 The setup consisted of an isolated canine heart suspended in a homogenous electrolytic medium in the correct anatomical position inside a tank molded in the shape of a ten-year old boy. The tank had 384 surface electrodes recording torso potentials and 242 rods with electrodes at their tips that formed an epicardial recording envelope around the heart.…”
Section: Isolated Canine Hearts Suspended In a Human Torso-shaped Tanmentioning
Potential-based inverse electrocardiography is a method for the noninvasive computation of epicardial potentials from measured body surface electrocardiographic data. From the computed epicardial potentials, epicardial electrograms and isochrones (activation sequences), as well as repolarization patterns can be constructed. We term this noninvasive procedure Electrocardiographic Imaging (ECGI). The method of choice for computing epicardial potentials has been the Boundary Element Method (BEM) which requires meshing the heart and torso surfaces and optimizing the mesh, a very time-consuming operation that requires manual editing. Moreover, it can introduce mesh-related artifacts in the reconstructed epicardial images. Here we introduce the application of a meshless method, the Method of Fundamental Solutions (MFS) to ECGI. This new approach that does not require meshing is evaluated on data from animal experiments and human studies, and compared to BEM. Results demonstrate similar accuracy, with the following advantages: 1. Elimination of meshing and manual mesh optimization processes, thereby enhancing automation and speeding the ECGI procedure. 2. Elimination of mesh-induced artifacts. 3. Elimination of complex singular integrals that must be carefully computed in BEM. 4. Simpler implementation. These properties of MFS enhance the practical application of ECGI as a clinical diagnostic tool.
“…The Tikhonov regularization method 76 with CRESO-determined regularization parameter 24 is used to stabilize the inverse procedure and obtain , similar to our previous ECGI inverse computations using mesh-based BEM. 15,16,32,33,47,56,61,62,[65][66][67][68][69][70][71] Once the coefficient vector is obtained, u(x) can be computed at any location in the domain using: (5) The epicardial potential can then be calculated using: (6) Epicardial potentials are calculated using (6) on many epicardial nodes; numbers are provided for each dataset in the Results section. An epicardial potential map, reflecting the spatial distribution of potentials on the epicardial surface, is computed every millisecond during the cardiac cycle.…”
Section: Formulating the Methods Of Fundamental Solutions For Ecgimentioning
confidence: 99%
“…62 The setup consisted of an isolated canine heart suspended in a homogenous electrolytic medium in the correct anatomical position inside a tank molded in the shape of a ten-year old boy. The tank had 384 surface electrodes recording torso potentials and 242 rods with electrodes at their tips that formed an epicardial recording envelope around the heart.…”
Section: Isolated Canine Hearts Suspended In a Human Torso-shaped Tanmentioning
Potential-based inverse electrocardiography is a method for the noninvasive computation of epicardial potentials from measured body surface electrocardiographic data. From the computed epicardial potentials, epicardial electrograms and isochrones (activation sequences), as well as repolarization patterns can be constructed. We term this noninvasive procedure Electrocardiographic Imaging (ECGI). The method of choice for computing epicardial potentials has been the Boundary Element Method (BEM) which requires meshing the heart and torso surfaces and optimizing the mesh, a very time-consuming operation that requires manual editing. Moreover, it can introduce mesh-related artifacts in the reconstructed epicardial images. Here we introduce the application of a meshless method, the Method of Fundamental Solutions (MFS) to ECGI. This new approach that does not require meshing is evaluated on data from animal experiments and human studies, and compared to BEM. Results demonstrate similar accuracy, with the following advantages: 1. Elimination of meshing and manual mesh optimization processes, thereby enhancing automation and speeding the ECGI procedure. 2. Elimination of mesh-induced artifacts. 3. Elimination of complex singular integrals that must be carefully computed in BEM. 4. Simpler implementation. These properties of MFS enhance the practical application of ECGI as a clinical diagnostic tool.
“…This technique uses 252 ECG electrodes mounted on a wearable vest to reconstruct epicardial potentials from torso potentials, see Figure 1. These are displayed as electrograms and activation sequences (isochrones) on the epicardial surface of the heart [76]. 10.1080/17434440.2018.1502084-F0001Figure 1.The 252-lead vest records torso surface electrograms.…”
Introduction: Cardiac resynchronization therapy (CRT) has emerged as one of the few effective treatments for heart failure. However, up to 50% of patients derive no benefit. Suboptimal left ventricle (LV) lead position is a potential cause of poor outcomes while targeted lead deployment has been associated with enhanced response rates. Image-fusion guidance systems represent a novel approach to CRT delivery, allowing physicians to both accurately track and target a specific location during LV lead deployment.Areas covered: This review will provide a comprehensive evaluation of how to define the optimal pacing site. We will evaluate the evidence for delivering targeted LV stimulation at sites displaying favorable viability or advantageous mechanical or electrical properties. Finally, we will evaluate several emerging image-fusion guidance systems which aim to facilitate optimal site selection during CRT.Expert commentary: Targeted LV lead deployment is associated with reductions in morbidity and mortality. Assessment of tissue characterization and electrical latency are critical and can be achieved in a number of ways. Ultimately, the constraints of coronary sinus anatomy have forced the exploration of novel means of delivering CRT including endocardial pacing which hold promise for the future of CRT delivery.
“…Electrocardiographic imaging (ECGI) (9) is a noninvasive cardiac electrical imaging modality that can image epicardial potentials, electrograms, and isochrones (activation sequences) using electrocardiographic measurements from many body surface locations together with heart-torso geometry obtained from computed tomography (CT). This imaging technique was extensively validated previously in normal and abnormal canine hearts (10)(11)(12)(13)(14). In a recent technical report (9), we introduced the methodology of ECGI application in humans, using single examples of ventricular and atrial activation in a normal subject and in patients with right bundle branch block, ventricular pacing, and atrial flutter.…”
Knowledge of normal human cardiac excitation stems from isolated heart or intraoperative mapping studies under nonphysiological conditions. Here, we use a noninvasive imaging modality (electrocardiographic imaging) to study normal activation and repolarization in intact unanesthetized healthy adults under complete physiological conditions. Epicardial potentials, electrograms, and isochrones were noninvasively reconstructed. The normal electrophysiological sequence during activation and repolarization was imaged in seven healthy subjects (four males and three females). Electrocardiographic imaging depicted salient features of normal ventricular activation, including timing and location of the earliest right ventricular (RV) epicardial breakthrough in the anterior paraseptal region, subsequent RV and left ventricular (LV) breakthroughs, apex-to-base activation of posterior LV, and late activation of LV base or RV outflow tract. The repolarization sequence was unaffected by the activation sequence, supporting the hypothesis that in normal hearts, local action potential duration (APD) determines local repolarization time. Mean activation recovery interval (ARI), reflecting local APD, was in the typical human APD range (235 ms). Mean LV apex-to-base ARI dispersion was 42 ms. Average LV ARI exceeded RV ARI by 32 ms. Atrial images showed activation spreading from the sinus node to the rest of the atria, ending at the left atrial appendage. This study provides previously undescribed characterization of human cardiac activation and repolarization under normal physiological conditions. A common sequence of activation was identified, with interindividual differences in specific patterns. The repolarization sequence was determined by local repolarization properties rather than by the activation sequence, and significant dispersion of repolarization was observed between RV and LV and from apex to base.noninvasive electrocardiographic imaging ͉ normal cardiac activation and repolarization ͉ normal sinus rhythm U nderstanding normal cardiac excitation provides a necessary baseline for understanding abnormal cardiac electrical activity and rhythm disorders of the heart, a major cause of death and disability. So far, knowledge of normal human cardiac excitation has been obtained mostly through extrapolation from animal studies, including canine (1, 2) and chimpanzee (3). In addition, human data have been obtained from intraoperative epicardial mapping (4-7) and isolated human hearts (8). Extrapolation of animal studies to humans is limited by interspecies differences in anatomy and electrophysiology. Also, the animal and human studies were conducted under nonphysiological conditions (e.g., anesthesia effects and heart exposure during intraoperative mapping; effects of isolation and absence of neural inputs, mechanical loading, and normal perfusion in isolated heart studies). Until now, it has not been possible to study cardiac excitation in intact healthy subjects under normal physiological conditions because of the unavailabili...
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