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152. Transmural dispersion of myofiber mechanics: implications for electrical heterogeneity in vivo

Author

Ashikaga, Hiroshi, Coppola, Benjamin A., Hopenfeld, Bruce, Leifer, Eric S., McVeigh, Elliot R., and Omens, Jeffrey H.

Subjects
Electrocardiography, Dogs, Models, Animal, Animals, Blood Pressure, Myocardial Contraction, Pericardium, Article, Ventricular Function, Left, Biomechanical Phenomena, Endocardium
Abstract

ObjectivesWe investigated whether transmural mechanics could yield insight into the transmural electrical sequence.BackgroundAlthough the concept of transmural dispersion of repolarization has helped explain a variety of arrhythmias, its presence in vivo is still disputable.MethodsWe studied the time course of transmural myofiber mechanics in the anterior left ventricle of normal canines in vivo (n = 14) using transmural bead markers under biplane cineradiography. In 4 of these animals, plunge electrodes were placed in the myocardial tissue within the bead set to measure transmural electrical sequence.ResultsThe onset of myofiber shortening was earliest at endocardial layers and progressively delayed toward epicardial layers (p < 0.001), resulting in transmural dispersion of myofiber shortening of 39 ms. The onset of myofiber relaxation was earliest at epicardial layers and most delayed at subendocardial layers (p = 0.004), resulting in transmural dispersion of myofiber relaxation of 83 ms. There was no significant transmural gradient in electrical repolarization (p = NS).ConclusionsDespite lack of evidence of significant transmural gradient in electrical repolarization in vivo, there is transmural dispersion of myofiber relaxation as well as shortening.

Published
2006

153. Association of Rate-Dependent Conduction Block Between Eccentric Coronary Sinus to Left Atrial Connections With Inducible Atrial Fibrillation and Flutter.

Author

Dong Huang, Marine, Joseph E., Jing-bo Li, Zghaib, Tarek, Ipek, Esra Gucuk, Sinha, Sunil, Spragg, David D., Hiroshi Ashikaga, Berger, Ronald D., Calkins, Hugh, Nazarian, Saman, Huang, Dong, Li, Jing-Bo, and Ashikaga, Hiroshi

Subjects
ATRIAL fibrillation, CARDIAC catheterization, CARDIAC pacing, CATHETER ablation, CORONARY arteries, HEART atrium, HEART beat, HEART block, HEART conduction system, RESEARCH funding, ATRIAL flutter
Abstract

Background: We sought to describe the prevalence and variability of coronary sinus (CS) and left atrial (LA) myocardium connections, their susceptibility to rate-dependent conduction block, and association with atrial fibrillation (AF) and flutter induction.Methods and Results: The study cohort included 30 consecutive AF patients (age 63.3±10.5 years, 63% male). Multipolar catheters were positioned in the CS, high right atrium (HRA), and LA parallel to and near the CS. Trains of 10 pacing stimuli were delivered during sinus rhythm from each of the following sites: CS proximal (CSp), CS distal (CSd), LA septum (LAs), lateral LA (LAl), and HRA, at the following cycle lengths: 1000, 500, 400, 300, and 250 ms, while recording from the other catheters. With the CS 9 to 10 bipole just inside the CS ostium, CS-LA connections were observed in 100% at CS 9 to 10, 30% at CS 7 to 8, 23% at CS 5 to 6, 23% at CS 3 to 4, and 97% at CS 1 to 2. Eighteen patients (60%) had AF/atrial flutter induced. Rate-dependent conduction block of a CS-LA connection at cycle length of ≥250 ms was present in 17 (94%) of those with versus none of those without AF/atrial flutter induction (P<0.001).Conclusions: Rate-dependent eccentric CS-LA conduction block is associated with AF/atrial flutter induction in patients with drug-refractory AF undergoing ablation. The presence of dual muscular CS-LA connections, coupled with unidirectional block in one limb, seems to serve as a substrate for single or multiple reentry beats, and arrhythmia induction. [ABSTRACT FROM AUTHOR]

Published
2017
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158. The Association of Pre-Existing Left Atrial Fibrosis with Clinical Variables in Patients Referred for Catheter Ablation of Atrial Fibrillation

Author

Dewire, Jane, primary, Khurram, Irfan M., additional, Pashakhanloo, Farhad, additional, Spragg, David, additional, Marine, Joseph E., additional, Berger, Ronald D., additional, Ashikaga, Hiroshi, additional, Rickard, John, additional, Zimmerman, Stefan L., additional, Zipunnikov, Vadim, additional, Calkins, Hugh, additional, and Nazarian, Saman, additional

Published
2014
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160. Relationship between left atrial appendage morphology and stroke in patients with atrial fibrillation

Author

Khurram, Irfan M., primary, Dewire, Jane, additional, Mager, Michael, additional, Maqbool, Farhan, additional, Zimmerman, Stefan L., additional, Zipunnikov, Vadim, additional, Beinart, Roy, additional, E. Marine, Joseph, additional, Spragg, David D., additional, Berger, Ronald D., additional, Ashikaga, Hiroshi, additional, Nazarian, Saman, additional, and Calkins, Hugh, additional

Published
2013
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162. Abstract 19078: Pre-Existing Left Atrial Fibrosis and Diastolic Dysfunction is Associated With Deterioration in Diastolic Function Following Left Atrial Ablation In Patients With Recurrent Atrial Fibrillation

Author

Khurram, Irfan, primary, Maqbool, Farhan, additional, Dewire, Jane, additional, Beinart, Roy, additional, Berger, Ronald D, additional, Marine, Joseph, additional, Spragg, David D, additional, Ashikaga, Hiroshi, additional, Calkins, Hugh, additional, and Nazarian, Saman, additional

Published
2013
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163. Feasibility of image-based simulation to estimate ablation target in human ventricular arrhythmia

Author

Ashikaga, Hiroshi, primary, Arevalo, Hermenegild, additional, Vadakkumpadan, Fijoy, additional, Blake, Robert C., additional, Bayer, Jason D., additional, Nazarian, Saman, additional, Muz Zviman, M., additional, Tandri, Harikrishna, additional, Berger, Ronald D., additional, Calkins, Hugh, additional, Herzka, Daniel A., additional, Trayanova, Natalia A., additional, and Halperin, Henry R., additional

Published
2013
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164. Phrenic Nerve Injury: An Underrecognized and Potentially Preventable Complication of Pulmonary Vein Isolation Using a Wide‐Area Circumferential Ablation Approach

Author

Yong Ji, Sang, primary, Dewire, Jane, additional, Barcelon, Bernadette, additional, Philips, Binu, additional, Catanzaro, John, additional, Nazarian, Saman, additional, Cheng, Alan, additional, Spragg, David, additional, Tandri, Harikrishna, additional, Bansal, Sandeep, additional, Ashikaga, Hiroshi, additional, Rickard, Jack, additional, Kolandaivelu, Aravindan, additional, Sinha, Sunil, additional, Marine, Joseph E., additional, Calkins, Hugh, additional, and Berger, Ronald, additional

Published
2013
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165. Association of Left Atrial Local Conduction Velocity With Late Gadolinium Enhancement on Cardiac Magnetic Resonance in Patients With Atrial Fibrillation.

Author

Kotaro Fukumoto, Habibi, Mohammadali, Ipek, Esra Gucuk, Zahid, Sohail, Khurram, Irfan M., Zimmerman, Stefan L., Zipunnikov, Vadim, Spragg, David, Hiroshi Ashikaga, Natalia Trayanova, Tomaselli, Gordon F., Rickard, John, Marine, Joseph E., Berger, Ronald D., Calkins, Hugh, Nazarian, Saman, Fukumoto, Kotaro, Ashikaga, Hiroshi, and Trayanova, Natalia

Subjects
ATRIAL fibrillation diagnosis, ACTION potentials, ATRIAL fibrillation, CARDIOVASCULAR system physiology, DIAGNOSTIC imaging, DYNAMICS, HEART atrium, HEART conduction system, HEART function tests, MAGNETIC resonance imaging, COMPUTERS in medicine, RESEARCH evaluation, RESEARCH funding, PREDICTIVE tests, RESEARCH bias, CONTRAST media, DRUG administration, DRUG dosage
Abstract

Background: Prior studies have demonstrated regional left atrial late gadolinium enhancement (LGE) heterogeneity on magnetic resonance imaging. Heterogeneity in regional conduction velocities is a critical substrate for functional reentry. We sought to examine the association between left atrial conduction velocity and LGE in patients with atrial fibrillation.Methods and Results: LGE imaging and left atrial activation mapping were performed during sinus rhythm in 22 patients before pulmonary vein isolation. The locations of 1468 electroanatomic map points were registered to the corresponding anatomic sites on 469 axial LGE image planes. The local conduction velocity at each point was calculated using previously established methods. The myocardial wall thickness and image intensity ratio defined as left atrial myocardial LGE signal intensity divided by the mean left atrial blood pool intensity was calculated for each mapping site. The local conduction velocity and image intensity ratio in the left atrium (mean ± SD) were 0.98 ± 0.46 and 0.95 ± 0.26 m/s, respectively. In multivariable regression analysis, clustered by patient, and adjusting for left atrial wall thickness, conduction velocity was associated with the local image intensity ratio (0.20 m/s decrease in conduction velocity per increase in unit image intensity ratio, P<0.001).Conclusions: In this clinical in vivo study, we demonstrate that left atrial myocardium with increased gadolinium uptake has lower local conduction velocity. Identification of such regions may facilitate the targeting of the substrate for reentrant arrhythmias. [ABSTRACT FROM AUTHOR]

Published
2016
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167. The critical isthmus sites of ischemic ventricular tachycardia are in zones of tissue heterogeneity, visualized by magnetic resonance imaging

Author

Estner, Heidi L., primary, Zviman, M. Muz, additional, Herzka, Dan, additional, Miller, Frank, additional, Castro, Valeria, additional, Nazarian, Saman, additional, Ashikaga, Hiroshi, additional, Dori, Yoav, additional, Berger, Ronald D., additional, Calkins, Hugh, additional, Lardo, Albert C., additional, and Halperin, Henry R., additional

Published
2011
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175. Feasibility of Real-Time Magnetic Resonance Imaging for Catheter Guidance in Electrophysiology Studies

Author

Nazarian, Saman, primary, Kolandaivelu, Aravindan, additional, Zviman, Menekhem M., additional, Meininger, Glenn R., additional, Kato, Ritsushi, additional, Susil, Robert C., additional, Roguin, Ariel, additional, Dickfeld, Timm L., additional, Ashikaga, Hiroshi, additional, Calkins, Hugh, additional, Berger, Ronald D., additional, Bluemke, David A., additional, Lardo, Albert C., additional, and Halperin, Henry R., additional

Published
2008
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176. Abnormal Sympathetic Innervation of Viable Myocardium and the Substrate of Ventricular Tachycardia After Myocardial Infarction

Author

Sasano, Tetsuo, primary, Abraham, M. Roselle, additional, Chang, Kuan-Cheng, additional, Ashikaga, Hiroshi, additional, Mills, Kevin J., additional, Holt, Daniel P., additional, Hilton, John, additional, Nekolla, Stephan G., additional, Dong, Jun, additional, Lardo, Albert C., additional, Halperin, Henry, additional, Dannals, Robert F., additional, Marbán, Eduardo, additional, and Bengel, Frank M., additional

Published
2008
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179. Magnetic Resonance–Based Anatomical Analysis of Scar-Related Ventricular Tachycardia

Author

Ashikaga, Hiroshi, primary, Sasano, Tetsuo, additional, Dong, Jun, additional, Zviman, M. Muz, additional, Evers, Robert, additional, Hopenfeld, Bruce, additional, Castro, Valeria, additional, Helm, Robert H., additional, Dickfeld, Timm, additional, Nazarian, Saman, additional, Donahue, J. Kevin, additional, Berger, Ronald D., additional, Calkins, Hugh, additional, Abraham, M. Roselle, additional, Marbán, Eduardo, additional, Lardo, Albert C., additional, McVeigh, Elliot R., additional, and Halperin, Henry R., additional

Published
2007
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180. Model of reentrant ventricular tachycardia based on infarct border zone geometry predicts reentrant circuit features as determined by activation mapping

Author

Ciaccio, Edward J., primary, Ashikaga, Hiroshi, additional, Kaba, Riyaz A., additional, Cervantes, Daniel, additional, Hopenfeld, Bruce, additional, Wit, Andrew L., additional, Peters, Nicholas S., additional, McVeigh, Elliot R., additional, Garan, Hasan, additional, and Coromilas, James, additional

Published
2007
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181. Reply

Author

Ashikaga, Hiroshi, primary, McVeigh, Elliot R., additional, and Omens, Jeffrey H., additional

Published
2007
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191. A Statistical Approach for Detecting Tubular Structures in Myocardial Infarct Scars.

Author

Vidal, Camille, Ashikaga, Hiroshi, and McVeigh, Elliot R.

Abstract

The presence of an infarct scar in the heart generates abnormal electrical pathways that may trigger the occurrence of arrhythmic episodes. While precise models of the electric propagation in the heart have been proposed, we are just starting to observe and analyze infarct scars using high-resolution imaging techniques. Recent observations have shown that the scar is a highly heterogeneous tissue, characterized by a complex interface with surrounding myocardium. For instance, the infarct scar is perforated by tunnels of live tissue, which could generate abnormal activation pathways and therefore facilitate arrhythmia episodes. In order to characterize the role of such structures, we need to first delineate them. In this paper, we propose an automatic method for the detection of these tunnels of normal tissue through scars in high resolution MR images. [ABSTRACT FROM AUTHOR]

Published
2009
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193. Estimating Local Apparent Conductivity with a 2-D Electrophysiological Model of the Heart.

Author

Frangi, Alejandro F., Radeva, Petia Ivanova, Santos, Andres, Hernandez, Monica, Moreau-Villéger, Valérie, Delingette, Hervé, Sermesant, Maxime, Ashikaga, Hiroshi, Faris, Owen, McVeigh, Elliot, and Ayache, Nicholas

Abstract

In this article we study the problem of estimating the parameters of a 2-D electrophysiological model of the heart from a set of temporal recordings of extracellular potentials. The chosen model is the reaction-diffusion model on the action potential proposed by Aliev and Panfilov. The strategy consists in building an error criterion based upon a comparison of depolarization times between the model and the measures. This error criterion is minimized in two steps : first a global and then a local adjustment of the model parameters. The feasibility of the approach is demonstrated on real measures on canine hearts, showing also the necessity to introduce anisotropy and probably a third spatial dimension in the model. [ABSTRACT FROM AUTHOR]

Published
2005
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194. In Vivo Validation of Longitudinal–Circumferential Area Change Ratio to Estimate Myofiber Shortening in the Heart.

Author

Ashikaga, Hiroshi and Omens, Jeffrey H.

Subjects
*LEFT heart ventricle, *HEART beat, *BIOMECHANICS, *DIAGNOSTIC imaging, *PHYSIOLOGIC strain, *CINERADIOGRAPHY
Abstract

The aim of this paper was to validate area change ratio (%AC ) against myofiber shortening (%λ_f) in the heart in vivo. % AC is emerging as a mechanical index that may approximate % λ_f by incorporating both circumferential and longitudinal shortening. However, the physiological significance of % AC remains unclear. We studied the time course of % AC in the anterior midleft ventricular wall of normal canine heart in vivo (n = 14) during atrial pacing over the entire cardiac cycle using transmurally implanted markers and biplane cineradiography (8 ms/frame). %AC was calculated as the myocardial area change relative to the elemental material area on the circumferential–longitudinal plane at the reference configuration (=end diastole). %AC was compared with % λ_f that was determined from the transmural fiber orientation directly measured in the heart tissue. The time course of both %AC and %λ _f was determined in the subepicardial, midwall, and subendocardial layers. The time course of %AC and % λ_f was significantly different, and the difference was more pronounced towards the endocardium. % AC consistently overestimated % λ_f. The timing of the peak % AC was significantly delayed compared to that of the peak % λ_f. We conclude that %AC is significantly different from % λ_f both in magnitude and timing in vivo. %AC overestimates %λ_f, and the overestimation is worse toward the endocardial layers. This may be a potentially important limitation when applying %AC to optimization and responder identification for cardiac resynchronization therapy. [ABSTRACT FROM PUBLISHER]

Published
2012
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195. Transmural mechanics at left ventricular epicardial pacing rate.

Author

Ashikaga, Hiroshi, Omens, Jeffrey H., Ingels Jr., Neil B., and Covell, James W.

Subjects
*LEFT heart ventricle, *MYOCARDIUM, *CARDIAC pacing, *HEART conduction system, *ELECTRIC properties of hearts, *CARDIOLOGY
Abstract

Left ventricular (LV) epicardial pacing acutely reduces wall thickening at the pacing site. Because LV epicardial pacing also reduces transverse shear deformation, which is related to myocardial sheet shear, we hypothesized that impaired end-systolic wall thickening at the pacing site is due to reduction in myocardial sheet shear deformation, resulting in a reduced contribution of sheet shear to wall thickening. We also hypothesized that epicardial pacing would reverse the transmural mechanical activation sequence and thereby mitigate normal transmural deformation. To test these hypotheses, we investigated the effects of LV epicardial pacing on transmural fiber-sheet mechanics by determining three-dimensional finite deformation during normal atrioventricular conduction and LV epicardial pacing in the anterior wall of normal dog hearts in vivo. Our measurements indicate that impaired end-systolic wall thickening at the pacing site was not due to selective reduction of sheet shear, but rather resulted from overall depression of fiber-sheet deformation, and relative contributions of sheet strains to wall thickening were maintained. These findings suggest lack of effective end-systolic myocardial deformation at the pacing site, most likely because the pacing site initiates contraction significantly earlier than the rest of the ventricle. Epicardial pacing also induced reversal of the transmural mechanical activation sequence, which depressed sheet extension and wall thickening early in the cardiac cycle, whereas transverse shear and sheet shear deformation were not affected. These findings suggest that normal sheet extension and wall thickening immediately after activation may require normal transmural activation sequence, whereas sheet shear deformation may be determined by local anatomy. [ABSTRACT FROM AUTHOR]

Published
2004
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196. Abstract 11195: Is Personalized Computational Model of Atrial Fibrillation Really Personalized?

Author

Lluch, Eric, Mihalef, Viorel, Vizitiu, Anamaria, Passerini, Tiziano, Audigier, Chloe, Halperin, Henry, Haschemi, Mehdiyar, Ashikaga, Hiroshi, and Mansi, Tommaso

Abstract

Introduction:Computational modeling-guided, personalized electrophysiology (EP) intervention for atrial fibrillation (AF) is an emerging paradigm of precision medicine. In the published models, advanced imaging and invasive mapping achieve personalization of cardiac anatomy. However, EP cellular personalization is less developed, and parameters are often assumed to be uniform across individual patientsHypothesis:Anatomical personalization alone is not sufficient to recapitulate the individual clinical features of AF in personalized models.Methods:For each of 57 patients (66±10 yr, 30 persistent) referred for catheter ablation of AF, we constructed a personalized 3-D model using pre-ablation CT, invasive mapping, and Courtemanche-Ramirez-Nattel atrial cell model. In the pre-ablation model, we performed virtual ramp pacing with cycle lengths at 200-120ms within the coronary sinus to induce AF. AF was defined as being inducible when it persists for >15s. Simulation was repeated for 5 different published sets of EP parameters of ionic currents. In total, >10k simulations were performed on an NVIDIA V100 GPU cluster, using the Lattice Boltzmann method with spatial resolution of 0.5mm and temporal resolution of 0.05ms, achieving a runtime of 24s per 1s of simulation (Fig. A).Results:While 100% AF inducibility was expected in the personalized pre-ablation models, AF inducibility varied between 27% and 96% depending on the set of ionic parameters used (Fig. B). The large variability of AF inducibility indicates that those models are highly sensitive to EP parameters, therefore anatomical personalization alone cannot adequately constrain the individual features of AF.Conclusions:The patient-specificity of the current paradigm of modeling-guided, personalized EP intervention is limited. There is an unmet clinical need for incorporation of personalized EP as well as anatomical parameters to achieve true precision medicine.

Published
2021
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198. Accurate Conduction Velocity Maps and Their Association With Scar Distribution on Magnetic Resonance Imaging in Patients With Postinfarction Ventricular Tachycardias.

Author

Aronis, Konstantinos N., Ali, Rheeda L., Prakosa, Adityo, Ashikaga, Hiroshi, Berger, Ronald D., Hakim, Joe B., Liang, Jialiu, Tandri, Harikrishna, Teng, Fei, Chrispin, Jonathan, and Trayanova, Natalia A.

Abstract

Background: Characterizing myocardial conduction velocity (CV) in patients with ischemic cardiomyopathy (ICM) and ventricular tachycardia (VT) is important for understanding the patient-specific proarrhythmic substrate of VTs and therapeutic planning. The objective of this study is to accurately assess the relation between CV and myocardial fibrosis density on late gadolinium-enhanced cardiac magnetic resonance imaging (LGE-CMR) in patients with ICM.Methods: We enrolled 6 patients with ICM undergoing VT ablation and 5 with structurally normal left ventricles (controls) undergoing premature ventricular contraction or VT ablation. All patients underwent LGE-CMR and electroanatomic mapping (EAM) in sinus rhythm (2960 electroanatomic mapping points analyzed). We estimated CV from electroanatomic mapping local activation time using the triangulation method that provides an accurate estimate of CV as it accounts for the direction of wavefront propagation. We evaluated the association between LGE-CMR intensity and CV with multilevel linear mixed models.Results: Median CV in patients with ICM and controls was 0.41 m/s and 0.65 m/s, respectively. In patients with ICM, CV in areas with no visible fibrosis was 0.81 m/s (95% CI, 0.59-1.12 m/s). For each 25% increase in normalized LGE intensity, CV decreased by 1.34-fold (95% CI, 1.25-1.43). Dense scar areas have, on average, 1.97- to 2.66-fold slower CV compared with areas without dense scar. Ablation lesions that terminated VTs were localized in areas of slow conduction on CV maps.Conclusions: CV is inversely associated with LGE-CMR fibrosis density in patients with ICM. Noninvasive derivation of CV maps from LGE-CMR is feasible. Integration of noninvasive CV maps with electroanatomic mapping during substrate mapping has the potential to improve procedural planning and outcomes. Visual Overview: A visual overview is available for this article. [ABSTRACT FROM AUTHOR]

Published
2020
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