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https://www.readbyqxmd.com/read/28231318/effects-of-na-channel-blockers-on-the-restitution-of-refractory-period-conduction-time-and-excitation-wavelength-in-perfused-guinea-pig-heart
#1
Oleg E Osadchii
Na+ channel blockers flecainide and quinidine can increase propensity to ventricular tachyarrhythmia, whereas lidocaine and mexiletine are recognized as safe antiarrhythmics. Clinically, ventricular fibrillation is often precipitated by transient tachycardia that reduces action potential duration, suggesting that a critical shortening of the excitation wavelength (EW) may contribute to the arrhythmic substrate. This study examined whether different INa blockers can produce contrasting effects on the rate adaptation of the EW, which would explain the difference in their safety profile...
2017: PloS One
https://www.readbyqxmd.com/read/28227423/dynamic-mapping-of-ventricular-function-from-cardiovascular-magnetic-resonance-imaging
#2
Maria Panayiotou, Peter Mountney, Alexander Brost, Daniel Toth, Tom Jackson, Jonathan M Behar, Christopher A Rinaldi, R James Housden, Kawal S Rhode, Maria Panayiotou, Peter Mountney, Alexander Brost, Daniel Toth, Tom Jackson, Jonathan M Behar, Christopher A Rinaldi, R James Housden, Kawal S Rhode, Alexander Brost, Tom Jackson, Maria Panayiotou, Christopher A Rinaldi, Jonathan M Behar, R James Housden, Kawal S Rhode, Daniel Toth, Peter Mountney
Heart failure is associated with substantial mortality and morbidity and remains the most common diagnosis in older patients. Based on experimental electrophysiologic studies, cardiac resynchronization therapy (CRT) for heart failure results in a maximum resynchronization effect when applied to the most delayed left ventricular (LV) site. Current clinical practice is to identify the optimal site using separate visualisation of scar and activation information. These must be mentally mapped into 3D, which is challenging and time-consuming for the electrophysiologist...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227376/electrocardiogram-reconstruction-from-high-resolution-voltage-optical-mapping
#3
Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton, Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton, Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton
Electrocardiogram recordings during opucal mapping experiments in heart tissue are commonly used tu monitor the health of the preparation and to obtain dominant frequencies during arrhythmic and defibrillatory studies. However the use of ECG reconstructed from optical mapping is seldom used and to date it has not been strictly validated. In this manuscript we present the first detailed validation and comparison of Optical Mapping ECG, or OM-ECG, with standard ECG recordings by calculating the electrostatic potential in space as a function of the voltage measured optically and describe the different approximations that can be used to obtain unipolar or bipolar ECG recordings...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226463/cardiac-katp-channel-modulation-by-16hz-magnetic-fields-a-theoretical-study
#4
Yuval Aharonovich, Mickey Scheinowitz, Sharon Zlochiver, Yuval Aharonovich, Mickey Scheinowitz, Sharon Zlochiver, Yuval Aharonovich, Sharon Zlochiver, Mickey Scheinowitz
Heart exposure to 16Hz magnetic fields (MFs) was shown to be cardio-protective for diseased hearts; still, the mechanism of this effect is unknown. We hypothesize that a possible one mechanism is an increased trans-membrane KATP channel open probability due to modulation of the degree of dissociation between K(+) ions, having a resonance frequency of 16Hz, and the channel selectivity filter. The Fan-Makielski Markovian KATP channel model was adopted, and the MF bio-effect was manifested by modulating the open probability of the channel using the predictive MF bio-effect parameter based on Binhi's quantum mechanics model...
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
#5
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/28226460/pro-arrhythmic-effect-of-heart-rate-variability-during-periodic-pacing
#6
Kanchan Kulkarni, Steven W Lee, Elena G Tolkacheva, Kanchan Kulkarni, Steven W Lee, Elena G Tolkacheva, Elena G Tolkacheva, Steven W Lee, Kanchan Kulkarni
Clinically, healthy hearts have been associated with a high ventricular heart rate variability (HRV) while diseased hearts have been known to exhibit low ventricular HRV. Hence, low HRV is suggested to be a marker of cardiac ventricular arrhythmias. Over the past few years, there has been considerable amount of interest in incorporating HRV in pacing to emulate healthy heart conditions and re-stabilize the electrical activity in diseased hearts. Recently, we used single cell numerical simulations to demonstrate that HRV incorporated into periodic pacing promotes alternans formation and thus, can be pro-arrhythmic...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226451/non-invasive-imaging-of-ventricular-activation-during-pacing-and-arrhythmia-methods-and-validation
#7
Long Yu, Steven Pogwizd, Bin He, Long Yu, Steven Pogwizd, Bin He, Bin He, Steven Pogwizd, Long Yu
Cardiovascular disease continued to be a leading killer world widely. Each year, about 400,000 cases of sudden cardiac arrest are reported in the U.S. alone. Clinically, radio-frequency ablative procedure has become widely applied in the treatment of ventricular arrhythmia. Non-invasive approaches have been demonstrated to be able to provide important information on the arrhythmogenesis and potentially assist in the clinical practice. In this work, we develop and validate a novel temporal sparse based imaging method, Cardiac Electrical Sparse Imaging (CESI)...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28224629/clinical-performance-of-magnetic-resonance-imaging-conditional-and-non-conditional-cardiac-implantable-electronic-devices
#8
Anand D Shah, Adarsh U Patel, Andrea Knezevic, Michael H Hoskins, David S Hirsh, Faisal M Merchant, Mikhael F El Chami, David B Delurgio, Anshul M Patel, Angel R Leon, Jonathan J Langberg, Michael S Lloyd
OBJECTIVES: This study compared risks associated with magnetic resonance imaging (MRI) in patients with non-MRI conditional and MRI conditional pacing and defibrillator systems with particular attention to clinically actionable outcomes. BACKGROUND: While recipients of new MRI conditional pacemaker and defibrillator systems may undergo MRI scanning with very low risk, safety and regulatory concerns persist regarding such scanning in recipients of non- MRI conditional systems...
February 22, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28216824/cardiac-troponin-i-a-potent-biomarker-for-myocardial-damage-assessment-following-high-voltage-electric-burn
#9
Arindam Bose, Chandra B Chhabra, Shobha Chamania, Nanda Hemvani, Dhananjay S Chitnis
Myocardial infarction (MI) following high voltage electric burn is very rare, and its pathogenesis remains controversial. Electrical burns represent only 4% of all burns. Hence, clinical managements have taken a slow pace in developing. The recent guidelines laid down by the cardiology societies include cardiac troponin I (cTnI) as the gold standard marker for the assessment of myocardial damage assessment. Two patients were admitted to our hospital at the different time with the same kind of high voltage electric burn...
September 2016: Indian Journal of Plastic Surgery: Official Publication of the Association of Plastic Surgeons of India
https://www.readbyqxmd.com/read/28213505/revealing-the-concealed-nature-of-long-qt-type-3-syndrome
#10
Amara Greer-Short, Sharon A George, Steven Poelzing, Seth H Weinberg
BACKGROUND: Gain-of-function mutations in the voltage-gated sodium channel (Nav1.5) are associated with the long-QT-3 (LQT3) syndrome. Nav1.5 is densely expressed at the intercalated disk, and narrow intercellular separation can modulate cell-to-cell coupling via extracellular electric fields and depletion of local sodium ion nanodomains. Models predict that significantly decreasing intercellular cleft widths slows conduction because of reduced sodium current driving force, termed "self-attenuation...
February 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28211263/increased-regurgitant-flow-causes-endocardial-cushion-defects-in-an-avian-embryonic-model-of-congenital-heart-disease
#11
Stephanie M Ford, Matthew T McPheeters, Yves T Wang, Pei Ma, Shi Gu, James Strainic, Christopher Snyder, Andrew M Rollins, Michiko Watanabe, Michael W Jenkins
BACKGROUND: The relationship between changes in endocardial cushion and resultant congenital heart diseases (CHD) has yet to be established. It has been shown that increased regurgitant flow early in embryonic heart development leads to endocardial cushion defects, but it remains unclear how abnormal endocardial cushions during the looping stages might affect the fully septated heart. The goal of this study was to reproducibly alter blood flow in vivo and then quantify the resultant effects on morphology of endocardial cushions in the looping heart and on CHDs in the septated heart...
February 17, 2017: Congenital Heart Disease
https://www.readbyqxmd.com/read/28204915/-acute-chest-pain-and-new-ecg-changes-in-pacemaker-patients-a%C3%A2-clinical-challenge
#12
Matthias Hoyme, Ralf Surber, P Christian Schulze, Dirk Prochnau
We report the case of a 82-year-old woman who was admitted to our institution with acute chest pain, nausea, and vomiting. Because of atrial fibrillation with intermittent bradycardia, a single-chamber pacemaker was implanted 4 years ago. The initial 12-lead ECG showed atrial fibrillation with a heart rate of 70 bpm, narrow QRS, and T‑wave inversions in the inferolateral leads. Coronary artery disease was excluded by immediate cardiac catheterization. A subsequent ECG three hours later showed a ventricular paced rhythm...
February 15, 2017: Herzschrittmachertherapie & Elektrophysiologie
https://www.readbyqxmd.com/read/28198133/left-ventricular-assist-device-therapy-in-advanced-heart-failure-patient-selection-and-outcomes
#13
REVIEW
Finn Gustafsson, Joseph G Rogers
Despite improvements in pharmacological therapy and pacing, prognosis in advanced heart failure (HF) remains poor, with a 1-year mortality of 25-50%. While heart transplantation provides excellent survival and quality of life for eligible patients, only a few can be offered this treatment due to shortage of donor organs. Implantable left ventricular assist device (LVAD) technology has improved considerably, and the currently used continuous flow devices may last >10 years in a patient. LVADs are being used increasingly both as bridge-to-transplantation and as destination therapy...
February 15, 2017: European Journal of Heart Failure
https://www.readbyqxmd.com/read/28194611/using-three-dimensional-echocardiography-to-guide-left-ventricle-lead-position-in-cardiac-resynchronization-therapy-does-it-make-any-difference
#14
Haitham A Badran, John Z Kamel, Tarek R Mohamed, Mohamed A Abdelhamid
BACKGROUND: Cardiac resynchronization therapy (CRT) is an effective treatment for patients with advanced heart failure. Nearly 30% of candidates are inadequate responders. Proper patient selection, left ventricle (LV) lead placement optimization, and optimization of the programming of the CRT device are important approaches to improve outcome of CRT. We examined the role of three-dimensional (3D) echocardiography in determining the optimal LV lead position as a method of optimizing CRT response...
February 13, 2017: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
https://www.readbyqxmd.com/read/28191665/apical-left-ventricular-myocardial-dysfunction-is-an-early-feature-of-cardiac-involvement-in-myotonic-dystrophy-type-1
#15
Rodrigue Garcia, Quentin Labarre, Bruno Degand, Pierre Ingrand, François Le Gal, Benjamin Bonnet, Anne Delaubier, Claire Guillou, Barnabas Gellen, Damien Coisne, Claire Bouleti, Luc Christiaens
INTRODUCTION: Left ventricular (LV) dysfunction is a major prognostic determinant in myotonic dystrophy type 1 (DM1). Therefore, markers of early-stage LV impairment may be useful. The aim of this study was to evaluate 2D echocardiographic LV strain in a cohort of DM1 patients with preserved left ventricular ejection fraction (LVEF) and to compare the results with matched controls. METHODS: This prospective single-center study included 33 consecutive DM1 patients between February 2014 and February 2015...
February 13, 2017: Echocardiography
https://www.readbyqxmd.com/read/28185354/eligibility-of-pacemaker-patients-for-subcutaneous-implantable-cardioverter-defibrillators
#16
James E Ip, Michael S Wu, Peter J Kennel, George Thomas, Christopher F Liu, Jim W Cheung, Steven M Markowitz, Bruce B Lerman
INTRODUCTION: The subcutaneous implantable cardioverter defibrillator (ICD) has emerged as a viable therapeutic option for patients who are deemed high risk for sudden cardiac death. Previous studies have shown that 7-15% of patients are not candidates for the S-ICD based on their intrinsic QRS/T-wave morphology. Presently, it is not known if the S-ICD can be considered as supplementary therapy in patients who are ventricularly paced. We sought to determine the proportion of ventricularly paced patients who would qualify for an S-ICD...
February 10, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28181107/stability-of-pacing-indices-and-need-for-pacing-in-cardiac-transplant-patients-over-1%C3%A2-year-of-follow-up
#17
Talha A Farid, Mohamed A Omer, Kensey Gosch, Ashley Moser, Bethany Austin, Anthony Magalski, Alan P Wimmer
BACKGROUND: A significant minority of cardiac transplant patients require permanent pacemaker (PPM) implant, primarily for sinus node dysfunction. The stability of pacing indices has not been determined in this unique patient population, and data regarding ongoing need for pacing are limited. METHODS: Pacing indices (sensing, threshold, and impedance) as well as the percentage of time patients required pacing were recorded, from 30 cardiac transplant patients that underwent PPM implant, over 1 year of follow-up...
February 8, 2017: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
https://www.readbyqxmd.com/read/28176924/high-stakes-and-high-emotions-providing-safe-care-in-canadian-emergency-departments
#18
Samina Ali, Denise Thomson, Timothy A D Graham, Sean E Rickard, Antonia S Stang
BACKGROUND: The high-paced, unpredictable environment of the emergency department (ED) contributes to errors in patient safety. The ED setting becomes even more challenging when dealing with critically ill patients, particularly with children, where variations in size, weight, and form present practical difficulties in many aspects of care. In this commentary, we will explore the impact of the health care providers' emotional reactions while caring for critically ill patients, and how this can be interpreted and addressed as a patient safety issue...
2017: Open Access Emergency Medicine: OAEM
https://www.readbyqxmd.com/read/28176398/the-relationship-of-antitachycardia-pacing-versus-shock-in-an-implantable-cardioverter-defibrillator-population-and-the-risk-of-mortality-just-an-association
#19
EDITORIAL
Jonathan C Hsu, Kurt S Hoffmayer
The mortality benefit of implantable cardioverter-defibrillator (ICD) therapy has been shown for both primary and secondary prevention of sudden cardiac death and in both ischemic and non-ischemic cardiomyopathy patients.(1-3) Although ICD shocks may be life-saving, avoiding shocks by attempting to terminate ventricular arrhythmias with anti-tachycardia pacing (ATP) may be beneficial as shocks can cause patient discomfort and may themselves be associated with increased mortality.(4) This article is protected by copyright...
February 8, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28169914/cardiac-autonomic-function-and-hot-flashes-among-perimenopausal-and-postmenopausal-women
#20
Carolyn J Gibson, Wendy Berry Mendes, Michael Schembri, Deborah Grady, Alison J Huang
OBJECTIVE: Abnormalities in autonomic function are posited to play a pathophysiologic role in menopausal hot flashes. We examined relationships between resting cardiac autonomic activity and hot flashes in perimenopausal and postmenopausal women. METHODS: Autonomic function was assessed at baseline and 12 weeks among perimenopausal and postmenopausal women (n = 121, mean age 53 years) in a randomized trial of slow-paced respiration for hot flashes. Pre-ejection period (PEP), a marker of sympathetic activation, was measured with impedance cardiography...
February 6, 2017: Menopause: the Journal of the North American Menopause Society
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