Ventricular stimulus site influences dynamic dispersion of repolarization in the intact human heart

Mincholé

et al. 2017

JAHA

Self Cite

BackgroundPatients with chronic heart failure are at high risk of sudden cardiac death (SCD). Increased dispersion of repolarization restitution has been associated with SCD, and we hypothesize that this should be reflected in the morphology of the T‐wave and its variations with heart rate. The aim of this study is to propose an electrocardiogram (ECG)‐based index characterizing T‐wave morphology restitution (TMR), and to assess its association with SCD risk in a population of chronic heart failure patients.Methods and ResultsHolter ECGs from 651 ambulatory patients with chronic heart failure from the MUSIC (MUerte Súbita en Insuficiencia Cardiaca) study were available for the analysis. TMR was quantified by measuring the morphological variation of the T‐wave per RR increment using time‐warping metrics, and its predictive power was compared to that of clinical variables such as the left ventricular ejection fraction and other ECG‐derived indices, such as T‐wave alternans and heart rate variability. TMR was significantly higher in SCD victims than in the rest of patients (median 0.046 versus 0.039, P<0.001). When TMR was dichotomized at TMR=0.040, the SCD rate was significantly higher in the TMR≥0.040 group (P<0.001). Cox analysis revealed that TMR≥0.040 was strongly associated with SCD, with a hazard ratio of 3.27 (P<0.001), independently of clinical and ECG‐derived variables. No association was found between TMR and pump failure death.ConclusionsThis study shows that TMR is specifically associated with SCD in a population of chronic heart failure patients, and it is a better predictor than clinical and ECG‐derived variables.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

T‐Wave Morphology Restitution Predicts Sudden Cardiac Death in Patients With Chronic Heart Failure

Ramírez

Mincholé

et al. 2017

JAHA

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“…The non-contact mapping data consisting of 256 unipolar electrograms were collected with a recording bandwidth of 0-300 Hz in all cases and measurements made with a filter band width of 0.1-25 Hz. Electrograms were exported and analysed using semi-automated custom software running in Matlab (The Mathworks Inc., MA, USA) (10,11). During pacing, the time from pacing artefact to the steepest negative deflection (dV/dt min ) was used as the local activation time (AT).…”

Section: Offline Analysesmentioning

confidence: 99%

“…We paced from the RV apex; however, it is known that if the pacing site is changed, this may shift activation and repolarisation (11) and may in some cases shift exit sites for VT. Simulations in ischaemic cardiomyopathy have demonstrated that the RVI map may also change (7) and criteria for the selection of optimal pacing site should be identified in further studies. Our study population was relatively small, and to enable clinical translation, prospective testing in a larger cohort would be necessary to enable clinical translation and demonstrate its superiority over other common substrate mapping procedures.…”

Section: Limitationsmentioning

confidence: 99%

Novel Repolarisation Metric Predicts Arrhythmia Origin And Clinical Events In ARVC And Brugada Syndrome

Martin

Srinivasan

et al. 2017

Preprint

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Structured abstractBackground: Initiation of re-entrant ventricular tachycardia (VT) involves complex interactions between activation (AT) and repolarization times (RT). The re-entry vulnerability index (RVI) is a recently proposed activation-repolarization metric designed to quantify tissue susceptibility to reentry. Objectives:The study aimed to test the feasibility of an RVI-based algorithm to predict the exit site of VT and occurrence of clinical events. ARVC/BrS patients with inducible VT had lower RVI G than those who were non-inducible or those with focal VT. Patients were followed up for 112 ± 19 months; those with clinical VT events had lower RVI G than those without VT or those with focal VT. Methods Conclusions:The proposed methodology based on RVI localises the origin of re-entrant but not focal ventricular arrhythmias and predicts clinical events. This index could be applied to target ablation for arrhythmias which are difficult to induce or are haemodynamically unstable and also risk stratify patients for ICD prophylaxis.peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/123422 doi: bioRxiv preprint first posted online Apr. 3, 2017; 3 Key words

“…During an electrophysiological study for supraventricular tachycardia in a patient with structurally normal ventricles, two decapolar catheters were placed in the left and right ventricles. Unipolar electrograms were referenced against the WCT, sampled at 2 KHz and recorded with amplifier with bandwidth 0.05-500 Hz as in previous studies [9]. Ventricular pacing was established from the RV apex.…”

Section: Experimental Datamentioning

confidence: 99%

Theoretical Assessment of a Repolarization Time Marker Based on the Intracardiac Bipolar Electrogram

Computing in Cardiology Conference (CinC)

Duijvenboden

Srinivasan

et al. 2017

Self Cite

The spatio-temporal organization of cardiac repolarization modulates the vulnerability to dangerous ventricular arrhythmias. Methodologies that provide accurate assessment of cardiac repolarization are of primary importance for a better understanding of cardiac electrophysiology and represent a potentially useful tool for clinical applications. The most commonly used repolarization time (RT) marker from extracellular recordings is derived from the unipolar electrogram (UEG). However, far field potentials and remote activity may in certain conditions bias this marker. In this paper, a RT marker based on the bipolar electrogram (BEG) is proposed. An analytical expression of the BEG based on a simple model of the cardiac extracellular potential is derived. According to the proposed analytical framework the BEG exhibits a repolarization wave whose extremum (maximum or minimum) corresponds to the average of the local RTs at the two electrodes of the bipole. The amplitude of this extremum is a function of the steepness of phase 3 of the action potentials, inter-electrode distance, conduction velocity and direction of wave-back propagation. A simulation study based on this analytical framework showed that for noisy to good signal quality (SNR of the UEG ≥ 10 dB), and for a typical inter-electrode distance of 2 mm, conduction velocity between 0.2 and 0.6 m/s, and an angle between conduction direction and the inter-electrode axis ≤ π/4, the median absolute error was lower than 6.8 ms while the median linear correlation between estimated and theoretical RT was higher than 0.91. Examples of RT derived from BEG recorded in a structurally normal heart in both the right and left ventricles demonstrate that the proposed procedure is feasible in human in-vivo studies.