keyword
MENU ▼
Read by QxMD icon Read
search

APD alternans

keyword
https://www.readbyqxmd.com/read/28894423/%C3%AE-adrenergic-inhibition-prevents-action-potential-and-calcium-handling-changes-during-regional-myocardial-ischemia
#1
Shannon R Murphy, Lianguo Wang, Zhen Wang, Philip Domondon, Di Lang, Beth A Habecker, Rachel C Myles, Crystal M Ripplinger
β-adrenergic receptor (β-AR) blockers may be administered during acute myocardial infarction (MI), as they reduce energy demand through negative chronotropic and inotropic effects and prevent ischemia-induced arrhythmogenesis. However, the direct effects of β-AR blockers on ventricular electrophysiology and intracellular Ca(2+) handling during ischemia remain unknown. Using optical mapping of transmembrane potential (with RH237) and sarcoplasmic reticulum (SR) Ca(2+) (with the low-affinity indicator Fluo-5N AM), the effects of 15 min of regional ischemia were assessed in isolated rabbit hearts (n = 19)...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28842915/roles-of-impaired-intracellular-calcium-cycling-in-arrhythmogenicity-of-diabetic-mouse-model
#2
Chung-Chuan Chou, Chien-Te Ho, Hui-Ling Lee, Yen Chu, Tzung-Hai Yen, Ming-Shien Wen, Shien-Fong Lin, Cheng-Hung Lee, Po-Cheng Chang
BACKGROUND: Diabetes mellitus is associated an increased risk of ventricular arrhythmias (VA), but the underlying electrophysiological mechanisms are not fully explored. This study was aimed to test whether dynamic factors and Cai handling play roles in arrhythmogenesis of a diabetic animal model. METHODS: We used 26 db/db type 2 diabetes mice and 28 control mice in this study. VA inducibility was evaluated in vivo under isoflurane general anesthesia. The intracellular Ca(2+) (Cai ) and membrane voltage (Vm ) signals of the Langendorff-perfused mouse hearts were simultaneously recorded using the optical mapping technique...
August 26, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28821956/effects-of-ageing-on-pro-arrhythmic-ventricular-phenotypes-in-incrementally-paced-murine-pgc-1%C3%AE-hearts
#3
Shiraz Ahmad, Haseeb Valli, Charlotte E Edling, Andrew A Grace, Kamalan Jeevaratnam, Christopher L-H Huang
A range of chronic clinical conditions accompany cardiomyocyte energetic dysfunction and constitute independent risk factors for cardiac arrhythmia. We investigated pro-arrhythmic and arrhythmic phenotypes in energetically deficient C57BL mice with genetic ablation of the mitochondrial promoter peroxisome proliferator-activated receptor-γ coactivator-1β (Pgc-1β), a known model of ventricular arrhythmia. Pro-arrhythmic and cellular action potential (AP) characteristics were compared in intact Langendorff-perfused hearts from young (12-16 week) and aged (> 52 week), wild-type (WT) and Pgc-1β (-/-) mice...
August 18, 2017: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/28662005/camkii-activation-promotes-cardiac-electrical-remodeling-and-increases-the-susceptibility-to-arrhythmia-induction-in-high-fat-diet-fed-mice-with-hyperlipidemia-conditions
#4
Peng Zhong, Dajun Quan, Yan Huang, He Huang
BACKGROUND: Obesity/hyperlipidemia is closely related to both atrial and ventricular arrhythmias. CaMKII, a multifunctional serine/threonine kinase, has been involved in cardiac arrhythmias of different etiology. However, its role in obesity/hyperlipidemia-related cardiac arrhythmia is unexplored. The aim of the present study was to determine the involvement of CaMKII in the process. METHODS: Adult male APOE-/- mice were fed a high-fat diet (HFD), administrated with KN93 (10mg/kg/2d), a specific inhibitor of CaMKII...
July 4, 2017: Journal of Cardiovascular Pharmacology
https://www.readbyqxmd.com/read/28290788/-the-myocardial-sleeves-of-the-pulmonary-veins-potential-implications-for-atrial-fibrillation
#5
Y V Egorov, L V Rozenshtrauh
Pulmonary veins (PVs) are thought to play an important role in the initiation of atrial fibrillation. However, systematic microelectrode studies from different regions of the left atria and PV myocardium remain limited. METHODS AND RESULTS: A 2-microelectrode technique was used to characterize electrophysiological properties of rat left atrial and PV myocardium, at baseline and during electrical stimulation. PV myocardium was characterized by prolonged action potential duration (APD) (74+/-2 ms in the PV mouth vs...
February 2017: Kardiologiia
https://www.readbyqxmd.com/read/28268303/effects-and-underlying-mechanisms-of-refractory-period-pacing-on-repolarization-dynamics-in-the-human-heart
#6
Diogo Santos, Michele Orini, Xin Zhou, Alfonso Bueno-Orovio, Ben Hanson, Peter Taggart, Martin Hayward, Blanca Rodriguez, Pier Lambiase
Repolarization alternans is related to the initiation of life threatening cardiac arrhythmias. Experimental and computational studies suggest that the abolishment of alternans using dynamic pacing protocols may prevent abnormal heart rhythms. In a recent animal study, refractory period pacing (RPP) on every other beat has shown promising results in alternans reduction. However, the cellular mechanisms underlying this therapy and its efficiency in human patients remain unclear. In this study, in vivo unipolar electrograms acquired during RPP from 240 epicardial sites from one patient were analysed...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226462/effects-and-underlying-mechanisms-of-refractory-period-pacing-on-repolarization-dynamics-in-the-human-heart
#7
Diogo Santos, Michele Orini, Xin Zhou, Alfonso Bueno-Orovio, Ben Hanson, Peter Taggart, Martin Hayward, Blanca Rodriguez, Pier Lambiase, Diogo Santos, Michele Orini, Xin Zhou, Alfonso Bueno-Orovio, Ben Hanson, Peter Taggart, Martin Hayward, Blanca Rodriguez, Pier Lambiase, Ben Hanson, Diogo Santos, Martin Hayward, Pier Lambiase, Alfonso Bueno-Orovio, Blanca Rodriguez, Michele Orini, Xin Zhou, Peter Taggart
Repolarization alternans is related to the initiation of life threatening cardiac arrhythmias. Experimental and computational studies suggest that the abolishment of alternans using dynamic pacing protocols may prevent abnormal heart rhythms. In a recent animal study, refractory period pacing (RPP) on every other beat has shown promising results in alternans reduction. However, the cellular mechanisms underlying this therapy and its efficiency in human patients remain unclear. In this study, in vivo unipolar electrograms acquired during RPP from 240 epicardial sites from one patient were analysed...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/27902841/dynamical-effects-of-calcium-sensitive-potassium-currents-on-voltage-and-calcium-alternans
#8
Matthew Kennedy, Donald M Bers, Nipavan Chiamvimonvat, Daisuke Sato
KEY POINTS: A mathematical model of a small conductance Ca(2)(+) -activated potassium (SK) channel was developed and incorporated into a physiologically detailed ventricular myocyte model. Ca(2+) -sensitive K(+) currents promote negative intracellular Ca(2+) to membrane voltage (CAi(2+) → Vm ) coupling. Increase of Ca(2+) -sensitive K(+) currents can be responsible for electromechanically discordant alternans and quasiperiodic oscillations at the cellular level. At the tissue level, Turing-type instability can occur when Ca(2+) -sensitive K(+) currents are increased...
April 1, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/27582498/suppression-of-ryanodine-receptor-function-prolongs-ca2-release-refractoriness-and-promotes-cardiac-alternans-in-intact-hearts
#9
Xiaowei Zhong, Bo Sun, Alexander Vallmitjana, Tao Mi, Wenting Guo, Mingke Ni, Ruiwu Wang, Ang Guo, Henry J Duff, Anne M Gillis, Long-Sheng Song, Leif Hove-Madsen, Raul Benitez, S R Wayne Chen
Beat-to-beat alternations in the amplitude of the cytosolic Ca(2+) transient (Ca(2+) alternans) are thought to be the primary cause of cardiac alternans that can lead to cardiac arrhythmias and sudden death. Despite its important role in arrhythmogenesis, the mechanism underlying Ca(2+) alternans remains poorly understood. Here, we investigated the role of cardiac ryanodine receptor (RyR2), the major Ca(2+) release channel responsible for cytosolic Ca(2+) transients, in cardiac alternans. Using a unique mouse model harboring a suppression-of-function (SOF) RyR2 mutation (E4872Q), we assessed the effect of genetically suppressing RyR2 function on Ca(2+) and action potential duration (APD) alternans in intact hearts, and electrocardiogram (ECG) alternans in vivo We found that RyR2-SOF hearts displayed prolonged sarcoplasmic reticulum Ca(2+) release refractoriness and enhanced propensity for Ca(2+) alternans...
November 1, 2016: Biochemical Journal
https://www.readbyqxmd.com/read/27385917/impaired-sarcoplasmic-reticulum-calcium-uptake-and-release-promote-electromechanically-and-spatially-discordant-alternans-a-computational-study
#10
Seth H Weinberg
Cardiac electrical dynamics are governed by cellular-level properties, such as action potential duration (APD) restitution and intracellular calcium (Ca) handling, and tissue-level properties, including conduction velocity restitution and cell-cell coupling. Irregular dynamics at the cellular level can lead to instabilities in cardiac tissue, including alternans, a beat-to-beat alternation in the action potential and/or the intracellular Ca transient. In this study, we incorporate a detailed single cell coupled map model of Ca cycling and bidirectional APD-Ca coupling into a spatially extended tissue model to investigate the influence of sarcoplasmic reticulum (SR) Ca uptake and release properties on alternans and conduction block...
2016: Clinical Medicine Insights. Cardiology
https://www.readbyqxmd.com/read/27384223/global-alternans-instability-and-its-effect-on-non-linear-wave-propagation-dynamical-wenckebach-block-and-self-terminating-spiral-waves
#11
Nele Vandersickel, Arne Defauw, Peter Dawyndt, Alexander V Panfilov
The main mechanism of formation of reentrant cardiac arrhythmias is via formation of waveblocks at heterogeneities of cardiac tissue. We report that heterogeneity and the area of waveblock can extend itself in space and can result formation of new additional sources, or termination of existing sources of arrhythmias. This effect is based on a new form of instability, which we coin as global alternans instability (GAI). GAI is closely related to the so-called (discordant) alternans instability, however its onset is determined by the global properties of the APD-restitution curve and not by its slope...
2016: Scientific Reports
https://www.readbyqxmd.com/read/27383322/effects-of-local-radiofrequency-denervation-on-ventricular-electrophysiological-properties-in-normal-and-acute-myocardial-ischemia-heart
#12
Y Huang, D-N Wang, P Liu, Y Song, H-M Cui, J-Y Zhang, J Blackwell, D-N Liao
OBJECTIVE: To observe the effects of local radiofrequency denervation on ventricular effective refractory periods, electrical alternans and ventricular arrhythmia susceptibility post myocardial infarction. MATERIALS AND METHODS: Thirty-four mongrel dogs were randomly divided into the normal heart group (n = 16, 8 in sham and 8 in local sympathetic denervation - LSD) and the acute myocardial ischemia (AMI) group (n = 18, 9 in control and 9 in LSD). The left cardiac sympathetic nerve was denervated with irrigated catheter radiofrequency ablation...
June 2016: European Review for Medical and Pharmacological Sciences
https://www.readbyqxmd.com/read/27336310/electrophysiology-of-heart-failure-using-a-rabbit-model-from-the-failing-myocyte-to-ventricular-fibrillation
#13
Aditya V S Ponnaluri, Luigi E Perotti, Michael Liu, Zhilin Qu, James N Weiss, Daniel B Ennis, William S Klug, Alan Garfinkel
Heart failure is a leading cause of death, yet its underlying electrophysiological (EP) mechanisms are not well understood. In this study, we use a multiscale approach to analyze a model of heart failure and connect its results to features of the electrocardiogram (ECG). The heart failure model is derived by modifying a previously validated electrophysiology model for a healthy rabbit heart. Specifically, in accordance with the heart failure literature, we modified the cell EP by changing both membrane currents and calcium handling...
June 2016: PLoS Computational Biology
https://www.readbyqxmd.com/read/27302910/using-delay-differential-equations-to-induce-alternans-in-a-model-of-cardiac-electrophysiology
#14
Justin Eastman, Julian Sass, Johnny M Gomes, Rodrigo Weber Dos Santos, Elizabeth M Cherry
Cardiac electrical alternans is a period-2 dynamical behavior with alternating long and short action potential durations (APD) that often precedes dangerous arrhythmias associated with cardiac arrest. Despite the importance of alternans, many current ordinary differential equations models of cardiac electrophysiology do not produce alternans, thereby limiting the use of these models for studying the mechanisms that underlie this condition. Because delay differential equations (DDEs) commonly induce complex dynamics in other biological systems, we investigate whether incorporating DDEs can lead to alternans development in cardiac models by studying the Fox et al...
September 7, 2016: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/27284405/restitution-analysis-of-alternans-using-dynamic-pacing-and-its-comparison-with-s1s2-restitution-in-heptanol-treated-hypokalaemic-langendorff-perfused-mouse-hearts
#15
Gary Tse, Sheung Ting Wong, Vivian Tse, Jie Ming Yeo
Action potential duration (APD) and conduction velocity restitution explain the dependence of these parameters on the previous diastolic interval (DI). It is considered to be an adaptive mechanism for preserving diastole at fast heart rates. Hypokalaemia is known to induce ventricular arrhythmias that could be prevented by heptanol, the gap junction uncoupler, mediated through increases in ventricular refractory period (VERP) without alterations in APDs. The present study investigated alternans and restitution properties during normokalaemia, hypokalaemia alone or hypokalaemia with heptanol (0...
June 2016: Biomedical Reports
https://www.readbyqxmd.com/read/27215536/mechanisms-linking-electrical-alternans-and-clinical-ventricular-arrhythmia-in-human-heart-failure
#16
J D Bayer, G G Lalani, E J Vigmond, S M Narayan, N A Trayanova
BACKGROUND: Mechanisms of ventricular tachycardia (VT) and ventricular fibrillation (VF) in patients with heart failure (HF) are undefined. OBJECTIVE: The purpose of this study was to elucidate VT/VF mechanisms in HF by using a computational-clinical approach. METHODS: In 53 patients with HF and 18 control patients, we established the relationship between low-amplitude action potential voltage alternans (APV-ALT) during ventricular pacing at near-resting heart rates and VT/VF on long-term follow-up...
September 2016: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/27072041/islands-of-spatially-discordant-apd-alternans-underlie-arrhythmogenesis-by-promoting-electrotonic-dyssynchrony-in-models-of-fibrotic-rat-ventricular-myocardium
#17
Rupamanjari Majumder, Marc C Engels, Antoine A F de Vries, Alexander V Panfilov, Daniël A Pijnappels
Fibrosis and altered gap junctional coupling are key features of ventricular remodelling and are associated with abnormal electrical impulse generation and propagation. Such abnormalities predispose to reentrant electrical activity in the heart. In the absence of tissue heterogeneity, high-frequency impulse generation can also induce dynamic electrical instabilities leading to reentrant arrhythmias. However, because of the complexity and stochastic nature of such arrhythmias, the combined effects of tissue heterogeneity and dynamical instabilities in these arrhythmias have not been explored in detail...
April 13, 2016: Scientific Reports
https://www.readbyqxmd.com/read/26961301/small-conductance-calcium-activated-potassium-current-and-the-mechanism-of-atrial-arrhythmia-in-mice-with-dysfunctional-melanocyte-like-cells
#18
Wei-Chung Tsai, Yi-Hsin Chan, Chia-Hsiang Hsueh, Thomas H Everett, Po-Cheng Chang, Eue-Keun Choi, Michael A Olaopa, Shien-Fong Lin, Changyu Shen, Maria Aleksandra Kudela, Michael Rubart-von der Lohe, Zhenhui Chen, Pooja Jadiya, Dhanendra Tomar, Emily Luvison, Nicholas Anzalone, Vickas V Patel, Peng-Sheng Chen
BACKGROUND: The melanin synthesis enzyme dopachrome tautomerase (Dct) regulates intracellular Ca(2+) in melanocytes. Homozygous Dct knockout (Dct(-/-)) adult mice are vulnerable to atrial arrhythmias (AA). OBJECTIVE: The purpose of this study was to determine whether apamin-sensitive small conductance Ca(2+)-activated K(+) (SK) currents are upregulated in Dct(-/-) mice and contribute to AA. METHODS: Optical mapping was used to study the membrane potential of the right atrium in Langendorff perfused Dct(-/-) (n = 9) and Dct(+/-) (n = 9) mice...
July 2016: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/26920995/local-heterogeneous-electrical-restitution-properties-of-rabbit-atria
#19
Amr Al Abed, Nigel H Lovell, Socrates Dokos
INTRODUCTION: This study aims to characterize the regional variability in rate-adaptation in the atria. METHODS AND RESULTS: Action potential (AP) responses to pulses with uniform as well as pseudo-random non-uniform pacing intervals were recorded from rabbit sino-atrial node, right and left atrial pectinate as well as pulmonary vein antrum tissue preparations using conventional intracellular glass microelectrodes. Steady-state restitution curves were reconstructed for various AP waveform metrics...
June 2016: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/26821570/chronic-administration-of-catestatin-improves-autonomic-function-and-exerts-cardioprotective-effects-in-myocardial-infarction-rats
#20
Dandan Wang, Tao Liu, Shaobo Shi, Ran Li, Yingguang Shan, Yan Huang, Dan Hu, Congxin Huang
Catestatin (CST), which is emerging as a novel cardiac modulator, can protect the heart against excessive sympathetic drive in hypertensive cardiomyopathy. The aim of this study is to investigate whether exogenous CST decreases excessive cardiac sympathetic drive and improves autonomic function and exerts cardioprotective effects in myocardial infarction (MI) rats. Rats were divided into a sham group, MI group, and MI plus CST (MI + CST) group. Four weeks later, the autonomic function of the animals was assessed by analyzing heart rate variability (HRV) and measuring plasma catecholamine...
January 27, 2016: Journal of Cardiovascular Pharmacology and Therapeutics
keyword
keyword
45073
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"