Cardiomyopathy is associated with cardiac Na+ channel downregulation that may contribute to arrhy... more Cardiomyopathy is associated with cardiac Na+ channel downregulation that may contribute to arrhythmias. Previously, we have shown that elevated intracellular NADH causes a decrease in cardiac Na+ current (INa) signaled by an increase in mitochondrial reactive oxygen species (ROS). In this study, we tested whether the NADH–mitochondria ROS pathway was involved in the reduction of INa in a nonischemic cardiomyopathic model and correlated the findings with myopathic human hearts.
Journal of Molecular and Cellular Cardiology, Volume 33, Issue 6, Pages A85, June 2001, Authors:V... more Journal of Molecular and Cellular Cardiology, Volume 33, Issue 6, Pages A85, June 2001, Authors:Vladimir Nikolski; Aleksandre Sambelashvill; Igor Efimov.
Abstract Optical mapping has become an increasingly important tool to study cardiac electrophysio... more Abstract Optical mapping has become an increasingly important tool to study cardiac electrophysiology in the past 20 years. Multiple methods are used to process and analyze cardiac optical mapping data, and no consensus currently exists regarding the optimum methods. The specific methods chosen to process optical mapping data are important because inappropriate data processing can affect the content of the data and thus alter the conclusions of the studies.
Abstract The development of human cardiovascular systems physiology is inhibited by the lack of m... more Abstract The development of human cardiovascular systems physiology is inhibited by the lack of multiscale functional physiological data, which represents human heart physiology at the molecular, cellular, tissue, organ, and system levels. We have developed an experimental approach to study explanted human hearts in vitro at multiple physiological scales with a wide array of imaging modalities.
Abstract Stability of a vortex was studied in a modified cellular automation model. The model inc... more Abstract Stability of a vortex was studied in a modified cellular automation model. The model includes dependence of wave velocity of excitation interval and front curvature. Two kinds of vortex instability are observed, as found also in models based on partial differential equations: meandering of the vortex and vortex drift in a heterogeneous medium.
Abstract: Using Optical Coherence Tomography (OCT), an emerging imaging modality, we have produce... more Abstract: Using Optical Coherence Tomography (OCT), an emerging imaging modality, we have produced both 3D and 4D images of cardiac architecture. We captured 3D images of rabbit Purkinje fiber networks and we also created a 4D representation of a beating stage 28 chicken embryo heart. For the 4D reconstruction, we generated a movie by employing a gated reconstruction technique.
Abstract The response of cardiac cells to the external electrical field is a crucial factor contr... more Abstract The response of cardiac cells to the external electrical field is a crucial factor contributing to the success and failure of defibrillation. We aimed to determine a possible contribution of electroporation to optically recorded response during high-intensity shocks. We applied 10 ms anodal and cathodal stimuli of different intensities to the rabbit heart epicardium during plateau phase of the action potential with 6-mm-diameter electrode.
Abstract Recently published optical mapping studies of larger mammals, including humans, have ide... more Abstract Recently published optical mapping studies of larger mammals, including humans, have identified functionally discrete sinoatrial exit pathways of activation. This is in line with earlier mapping studies of the dog and the human but in contrast with findings in the mouse and the rabbit, wherein a propagation wave front pattern of activation has been described.
Abstract There is a need for accurate measurements of mechanical strain and motion of the heart b... more Abstract There is a need for accurate measurements of mechanical strain and motion of the heart both in vitro and in vivo. We have developed a new structured-light imaging system capable of epicardial shape measurement at 333 fps at a resolution of 768× 768 pixels. Here we present proof-of-concept data from our system applied to a beating rabbit heart in vitro to measure epicardial mechanics.
Summary Technological advances often precede scientific breakthroughs that have led to leaps in ou... more Summary Technological advances often precede scientific breakthroughs that have led to leaps in our understanding of human physiology. The advent of the electrical galvanometer Was a landmark advancement that enabled careful study of the electrical activation of the heart.
Optical imaging of voltage and calcium in the heart, which we pioneered 2 decades ago, 1–3 is ind... more Optical imaging of voltage and calcium in the heart, which we pioneered 2 decades ago, 1–3 is indeed an important and increasingly more valuable technique in the investigation of arrhythmia mechanisms, and we concur that significant advances in the field justify a review of recent progress. In their recent review of the topic, Herron et al tackle a presentation of the essential components that are necessary to build state-of-the-arts optical mapping instruments.
We thank Drs Selvaraj and Nair for the opportunity to discuss the clinical relevance of our recen... more We thank Drs Selvaraj and Nair for the opportunity to discuss the clinical relevance of our recent findings in explanted human hearts and to bridge the gap between clinical and basic electrophysiology research methodologies. Using the basic science methodology of optical mapping, which is not yet available in clinical electrophysiological laboratories, we have recently found that end-stage heart failure results in anatomically heterogeneous repolarization remodeling in humans.
Cardiomyopathy is associated with cardiac Na+ channel downregulation that may contribute to arrhy... more Cardiomyopathy is associated with cardiac Na+ channel downregulation that may contribute to arrhythmias. Previously, we have shown that elevated intracellular NADH causes a decrease in cardiac Na+ current (INa) signaled by an increase in mitochondrial reactive oxygen species (ROS). In this study, we tested whether the NADH–mitochondria ROS pathway was involved in the reduction of INa in a nonischemic cardiomyopathic model and correlated the findings with myopathic human hearts.
Journal of Molecular and Cellular Cardiology, Volume 33, Issue 6, Pages A85, June 2001, Authors:V... more Journal of Molecular and Cellular Cardiology, Volume 33, Issue 6, Pages A85, June 2001, Authors:Vladimir Nikolski; Aleksandre Sambelashvill; Igor Efimov.
Abstract Optical mapping has become an increasingly important tool to study cardiac electrophysio... more Abstract Optical mapping has become an increasingly important tool to study cardiac electrophysiology in the past 20 years. Multiple methods are used to process and analyze cardiac optical mapping data, and no consensus currently exists regarding the optimum methods. The specific methods chosen to process optical mapping data are important because inappropriate data processing can affect the content of the data and thus alter the conclusions of the studies.
Abstract The development of human cardiovascular systems physiology is inhibited by the lack of m... more Abstract The development of human cardiovascular systems physiology is inhibited by the lack of multiscale functional physiological data, which represents human heart physiology at the molecular, cellular, tissue, organ, and system levels. We have developed an experimental approach to study explanted human hearts in vitro at multiple physiological scales with a wide array of imaging modalities.
Abstract Stability of a vortex was studied in a modified cellular automation model. The model inc... more Abstract Stability of a vortex was studied in a modified cellular automation model. The model includes dependence of wave velocity of excitation interval and front curvature. Two kinds of vortex instability are observed, as found also in models based on partial differential equations: meandering of the vortex and vortex drift in a heterogeneous medium.
Abstract: Using Optical Coherence Tomography (OCT), an emerging imaging modality, we have produce... more Abstract: Using Optical Coherence Tomography (OCT), an emerging imaging modality, we have produced both 3D and 4D images of cardiac architecture. We captured 3D images of rabbit Purkinje fiber networks and we also created a 4D representation of a beating stage 28 chicken embryo heart. For the 4D reconstruction, we generated a movie by employing a gated reconstruction technique.
Abstract The response of cardiac cells to the external electrical field is a crucial factor contr... more Abstract The response of cardiac cells to the external electrical field is a crucial factor contributing to the success and failure of defibrillation. We aimed to determine a possible contribution of electroporation to optically recorded response during high-intensity shocks. We applied 10 ms anodal and cathodal stimuli of different intensities to the rabbit heart epicardium during plateau phase of the action potential with 6-mm-diameter electrode.
Abstract Recently published optical mapping studies of larger mammals, including humans, have ide... more Abstract Recently published optical mapping studies of larger mammals, including humans, have identified functionally discrete sinoatrial exit pathways of activation. This is in line with earlier mapping studies of the dog and the human but in contrast with findings in the mouse and the rabbit, wherein a propagation wave front pattern of activation has been described.
Abstract There is a need for accurate measurements of mechanical strain and motion of the heart b... more Abstract There is a need for accurate measurements of mechanical strain and motion of the heart both in vitro and in vivo. We have developed a new structured-light imaging system capable of epicardial shape measurement at 333 fps at a resolution of 768× 768 pixels. Here we present proof-of-concept data from our system applied to a beating rabbit heart in vitro to measure epicardial mechanics.
Summary Technological advances often precede scientific breakthroughs that have led to leaps in ou... more Summary Technological advances often precede scientific breakthroughs that have led to leaps in our understanding of human physiology. The advent of the electrical galvanometer Was a landmark advancement that enabled careful study of the electrical activation of the heart.
Optical imaging of voltage and calcium in the heart, which we pioneered 2 decades ago, 1–3 is ind... more Optical imaging of voltage and calcium in the heart, which we pioneered 2 decades ago, 1–3 is indeed an important and increasingly more valuable technique in the investigation of arrhythmia mechanisms, and we concur that significant advances in the field justify a review of recent progress. In their recent review of the topic, Herron et al tackle a presentation of the essential components that are necessary to build state-of-the-arts optical mapping instruments.
We thank Drs Selvaraj and Nair for the opportunity to discuss the clinical relevance of our recen... more We thank Drs Selvaraj and Nair for the opportunity to discuss the clinical relevance of our recent findings in explanted human hearts and to bridge the gap between clinical and basic electrophysiology research methodologies. Using the basic science methodology of optical mapping, which is not yet available in clinical electrophysiological laboratories, we have recently found that end-stage heart failure results in anatomically heterogeneous repolarization remodeling in humans.
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Papers by Igor Efimov