T-wave alternans (TWA) has been investigated as a marker for susceptibility to lethal ventricular arrhythmia. In this article, we studied intracardiac TWA and ischemia as predictors of spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) in a canine model of coronary artery occlusion (CAO). Anesthetized, open-chest dogs were studied. Electrograms from intracardiac bipolar electrodes (IBEs) were assessed for TWA and spontaneous VT or VF. TWA was defined on IBE as T wave voltage change on every other complex. In each heart, we examined 62 electrograms measured in the risk zone and surrounding normal sites, filtered from 3 to 1300 Hz. Ischemia was measured as percent of all IBE recorded that had QRS voltage drop >45%. Mapping localized the three-dimensional origin of spontaneous VT or VF. The data from dogs with VF (n = 5), VT (n = 8), or controls (no VT or VF, n = 8) were analyzed before left CAO, at the 20th min after CAO and times immediately preceding VT and VF. We found a correlation between intracardiac TWA and ischemia. More importantly, increases in intracardiac TWA peaked immediately preceding spontaneous VF and VT and were significantly higher compared to controls at comparable times. At VT/VF origins and adjacent sites, the mean TWA magnitude and discordance of TWA distinguished between VT/VF and controls at comparable times but not between VT and VF or between reentry and focal mechanisms. TWA was more common than ischemia at VT/VF origins. In summary, changes in intracardiac TWA and ischemia correlate with impending spontaneous VT/VF in a clinically applicable canine model of CAO.
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http://dx.doi.org/10.1016/j.trsl.2011.07.001 | DOI Listing |
Can J Anaesth
September 2020
Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Purpose: Non-invasive cerebral oxygen saturation (ScO) monitoring is an established tool in the intraoperative phase of pediatric congenital cardiac surgery (CCS). This study investigated the association between ScO and postoperative outcome by investigating both baseline ScO values and intraoperative desaturations from baseline.
Methods: All CCS procedures performed in the period 2010-2017 in our institution in which ScO was monitored were included in this historical cohort study.
Sensors (Basel)
May 2020
Department of Signal Theory and Communications, Telematics and Computing Systems, Rey Juan Carlos University, 28943 Fuenlabrada, Madrid, Spain.
During the last years, attention and controversy have been present for the first commercially available equipment being used in Electrocardiographic Imaging (ECGI), a new cardiac diagnostic tool which opens up a new field of diagnostic possibilities. Previous knowledge and criteria of cardiologists using intracardiac Electrograms (EGM) should be revisited from the newly available spatial-temporal potentials, and digital signal processing should be readapted to this new data structure. Aiming to contribute to the usefulness of ECGI recordings in the current knowledge and methods of cardiac electrophysiology, we previously presented two results: First, spatial consistency can be observed even for very basic cardiac signal processing stages (such as baseline wander and low-pass filtering); second, useful bipolar EGMs can be obtained by a digital processing operator searching for the maximum amplitude and including a time delay.
View Article and Find Full Text PDFPacing Clin Electrophysiol
November 2014
Federation of Cardiology, University Hospital Rangueil, Toulouse, France.
Background: The aim of the Endocardial T-Wave Alternans Study was to prospectively assess the presence of T-wave alternans (TWA) or beat-to-beat repolarization changes on implantable cardioverter-defibrillator (ICD)-stored electrograms (EGMs) immediately preceding the onset of spontaneous ventricular tachycardia (VT) or fibrillation (VF).
Methods: Thirty-seven VT/VF episodes were compared to 116 baseline reference EGMs from the same 57 patients. A Bayesian model was used to estimate the T-wave waveform in each cardiac beat and a set of 10 parameters was selected to segment each detected T wave.
Background: T-wave alternans (TWA) has been implicated in the pathogenesis of ventricular arrhythmias and sudden cardiac death. However, to estimate and suppress TWA effectively, the phase of TWA must be accurately determined.
Methods And Results: We developed a method that computes the beat-by-beat integral of the T-wave morphology, over time points within the T-wave with positive alternans.
Heart Rhythm
July 2012
Department of Cardiovascular Medicine, Toho University Medical Center, Tokyo, Japan.
Background: It has been reported that intracardiac electrogram T-wave alternans (IE-TWA) is greater prior to spontaneous ventricular tachyarrhythmia (VTA) than for baseline recordings.
Objective: To investigate IE-TWA just prior to VTA episodes and at baseline and compare these with microvolt TWA (M-TWA) measured during exercise.
Methods: We analyzed right ventricular ring-can electrogram recordings just prior to VTA episodes and compared T-wave pattern and degree of variation to baseline recordings from 3 patients (2 with idiopathic ventricular fibrillation and 1 with hypertrophic cardiomyopathy) who were enrolled in the Japan Intracardiac Electrogram TWA Study of ICD Recipients.
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