Activation Wavefront Research Articles

Abstract 13691: High Burden of Sensing Changes in Periprocedural TAVR Patients With Pre-Existing CIEDs Presents A Unique Challenge

Introduction: The data on the management of patients undergoing transcatheter aortic valve replacement (TAVR) with pre-existing cardiac implantable electronic devices (CIED) is scarce. Objective: We describe the R wave sensing changes following TAVR in a patient with CIED and describe CIED behavior peri procedurally in a high volume center over 8 years. Results: A 64 year old male patient with a history of non-ischemic cardiomyopathy and a secondary prevention dual-chamber ICD presented for generator change. Six months prior, he underwent TAVR (29mm ES S3). Post TAVR, he developed a new RBBB. Device interrogation revealed a significant drop in sensed R waves from 9mV to 1.5mV which temporally correlated with TAVR (Figure 1). Pacing thresholds and impedance were stable. Chest x-rays showed stable lead position. Given drop in R wave sensing, successful defibrillation threshold testing was performed with generator change. Of the 115 patients with pre-existing CIEDs undergoing TAVR between 2012-2020, 23.5% (27 patients) showed changes in sensing (mean 3.0±2.5mV) peri procedurally with minimal change in impedance or threshold with no correlation with QRS changes. Conclusions: To our knowledge, this is the 1st reported case of a change in sensed R waves due to conduction disturbance following TAVR. We hypothesize this occurred due to a change in the activation wavefront sensed by the right ventricular lead following the development of new RBBB. Up to a quarter of patients have sensing fluctuations in our experience. Consideration of pre and post device interrogation with TAVR could be of value.

Combining endocardial mapping and electrocardiographic imaging (ECGI) for improving PVC localization: A feasibility study

IntroductionAccurate reconstruction of cardiac activation wavefronts is crucial for clinical diagnosis, management, and treatment of cardiac arrhythmias. Furthermore, reconstruction of activation profiles within the intramural myocardium has long been impossible because electrical mapping was only performed on the endocardial surface. Recent advancements in electrocardiographic imaging (ECGI) have made endocardial and epicardial activation mapping possible. We propose a novel approach to use both endocardial and epicardial mapping in a combined approach to reconstruct intramural activation times. ObjectiveTo implement and validate a combined epicardial/endocardial intramural activation time reconstruction technique. MethodsWe used 11 simulations of ventricular activation paced from sites throughout myocardial wall and extracted endocardial and epicardial activation maps at approximate clinical resolution. From these maps, we interpolated the activation times through the myocardium using thin-plate-spline radial basis functions. We evaluated activation time reconstruction accuracy using root-mean-squared error (RMSE) of activation times and the percent of nodes within 1 ms of the ground truth. ResultsReconstructed intramural activation times showed an RMSE and percentage of nodes within 1 ms of the ground truth simulations of 3 ms and 70%, respectively. In the worst case, the RMSE and percentage of nodes were 4 ms and 60%, respectively. ConclusionWe showed that a simple, yet effective combination of clinical endocardial and epicardial activation maps can accurately reconstruct intramural wavefronts. Furthermore, we showed that this approach provided robust reconstructions across multiple intramural stimulation sites.

B-PO05-085 REGIONAL CONDUCTION VELOCITY MEASUREMENTS: COMPARING CONTACT AND NON-CONTACT ACTIVATION TECHNIQUES

Non-contact (NC) mapping efficiently acquires global activation wavefronts and is potentially more accurate than contact (C) mapping due to elimination of C-related artifact. Common areas of conduction velocity (CV) deceleration during sinus and paced rhythms have been used to characterize the atrial substrate, however, such analysis with C mapping is time-consuming. Compare CV using C local activation timing (LAT) and NC LAT maps. Retrospective analysis of CV of NC LAT maps (SuperMap, Acutus Medical) obtained from 22 clinical pts were compared to CV of C LAT maps created from unique C EGMs concurrently acquired with the AcQMap Catheter. NC LAT maps were created from charge density EGMs inversely computed from NC measurements. For both C and NC datasets, CVs were computed using a polynomial surface fit. C and NC CV vectors were compared for both direction and magnitude using Bland-Altman analysis. C and NC derived CV comparisons (n=780) were made from 29 maps of SR, AT/AFL or pacing. Mean acquisition time/map was 2 min 40s ± 1 min. Figure 1 shows a C and NC generated LAT map with corresponding CV overlaid and Bland-Altman agreement limits. Bland-Altman analysis showed bias between both methods was small with the confidence interval for C CV magnitude at 6.0 ± 17.0 cm/s and for C CV direction being 9.8±16.6°. NC LAT maps were efficiently acquired, and NC CV measurements were consistent when compared to C CV. Results of this study are consistent with analysis of CV from a high-density grid compared to optical mapping (Masse et al, 2016). Accuracy and time efficiencies achieved by NC mapping may facilitate more widespread use of substrate characterization.

B-PO02-094 QUANTIFYING THE VARIABILITY OF BIPOLAR VOLTAGE AMPLITUDE WITH SENSING ANGLE IN RESIDUAL CONDUCTION ISTHMUSES IN ATRIAL SCAR

The angle between the activation wavefront and bipole may conceal the conduction isthmus in conventional bipolar voltage mapping, but the extent of variability of electrogram (EGM) voltage amplitude with directional changes has not been quantified. Using a well-defined model of discrete atrial conduction, we sought to use Omnipolar Technology (OT) to assess variability of voltage amplitude as a function of sensing angle, in sites of residual conduction and scar tissue. During redo pulmonary vein isolation (PVI) procedures, baseline voltage maps were acquired during coronary sinus pacing (500 ms) using a rectangular 16-pole catheter (HD Grid). During retrospective analysis with OT research software, all EGM’s ≤1 cm radius from the site of PVI were classified as GAP (vs No-GAP; Panel A) The variability of voltage amplitude (OT-ΔV) with sensing angle (θ) was computed as the difference between the maximum and minimum voltages (OT-Vmax - OT-Vmin), in both GAP and No-GAP subregions (Panels A & B). 23 GAP sites were identified in 12 of 15 consecutive patients studied. 3464 EGM’s (1386 GAP vs 2078 No-GAP) were analyzed. Global mean OT-ΔV was 0.46±0.80 mV. GAP regions showed significantly (P<0.0001) higher OT-ΔV as compared with No-GAP regions (0.80±1.03 mV vs 0.24±0.47 mV respectively; Panel C) The mean Δθ angle for OT-ΔV was similar in both GAP and No-GAP regions (88.6±11.3° vs 88.0±13.6°, P=0.1; Panel D). (1) The variability of voltage amplitude as a function of bipole orientation can be significant, especially in GAP regions (0.80±1.03 mV). (2) OT-ΔV holds promise for identification of residual conduction within atrial scar tissue.

Adaptive system for correcting optical aberrations of high-power lasers with dynamic determination of the reference wavefront

We present the results of the aberration correction of laser radiation wavefront using a dynamic method for determining the reference wavefront. The method, which is based on the processing of synchronously obtained data on the near- and far-field zones, significantly improves the focusing quality with active wavefront correction, especially under conditions of dynamic aberrations. An increase in the Strehl number S from 0.7 to 0.86 is demonstrated when a beam 18 cm in diameter is focused by an F/2.5 parabolic mirror.

Ventricular electrical storm after Micra™ leadless pacemaker implant

Peri- and post-procedural ventricular tachycardia (VT) is a rare complication after leadless pacemaker implantation and requires an individualized approach. In this case report we describe the management of VT in a patient with subendocardial scarring due to prior coronary artery disease who presented with monomorphic VT the day after implant. The etiology was found to be related to the novel ventricular activation wavefront by ventricular pacing which induced a reentrant circuit dependent on pre-existing myocardial substrate. Invasive electrophysiologic study and ablation is a safe and successful treatment strategy in selected patients with evidence of myocardial scarring.

Active near-infrared wavefront engineering employing geometric phase metasurfaces combined with phase-change materials

In recent years, with the remarkable development of micro–nano technology, phase change materials (PCMs) with superior tunable and nonvolatile functionality are integrated into metasurfaces, which has aroused huge interests among scientific communities. However, the imaginary part of refractive index of PCMs in the crystalline phase is large in the near-infrared region (NIR), leading to the strong absorption of device and limiting the development of the PCMs in the NIR. Here, we propose and investigate the hybrid metasurface with asymmetric double-split rings. We use PCM and silica (SiO2) as the composite dielectric layer, which can efficiently reduce the impact of the high imaginary part of the refractive index PCM in the crystalline phase. Moreover, metasurfaces with two types can obtain two different resonances. Furthermore, by inducing the phase change of the PCM, we can move the short-wavelength resonance peak to the position of another long-wavelength resonance peak. Meanwhile, we can add two sets of different phases to two different types of metasurfaces. Thus, the active metasurface based on the PCM can be used to achieve the active wavefront in the NIR. Hence, the proposed metasurface based on the PCM can be applied in tunable beam switching, reconfigurable holography, and other reconfigurable optical components in the NIR.

Quantifying the spatiotemporal influence of acute myocardial ischemia on volumetric conduction velocity

IntroductionAcute myocardial ischemia occurs when coronary perfusion to the heart is inadequate, which can perturb the highly organized electrical activation of the heart and can result in adverse cardiac events including sudden cardiac death. Ischemia is known to influence the ST and repolarization phases of the ECG, but it also has a marked effect on propagation (QRS); however, studies investigating propagation during ischemia have been limited. MethodsWe estimated conduction velocity (CV) and ischemic stress prior to and throughout 20 episodes of experimentally induced ischemia in order to quantify the progression and correlation of volumetric conduction changes during ischemia. To estimate volumetric CV, we 1) reconstructed the activation wavefront; 2) calculated the elementwise gradient to approximate propagation direction; and 3) estimated conduction speed (CS) with an inverse-gradient technique. ResultsWe found that acute ischemia induces significant conduction slowing, reducing the global median speed by 20 cm/s. We observed a biphasic response in CS (acceleration then deceleration) early in some ischemic episodes. Furthermore, we noted a high temporal correlation between ST-segment changes and CS slowing; however, when comparing these changes over space, we found only moderate correlation (corr. = 0.60). DiscussionThis study is the first to report volumetric CS changes (acceleration and slowing) during episodes of acute ischemia in the whole heart. We showed that while CS changes progress in a similar time course to ischemic stress (measured by ST-segment shifts), the spatial overlap is complex and variable, showing extreme conduction slowing both in and around regions experiencing severe ischemia.

Active Dielectric Metasurfaces for Switchable Terahertz Beam Steering and Focusing

Conventional metasurfaces often manipulate light propagation in a passive way, which cannot satisfy the dynamic operation requirements of many practical applications. Integrating functional materials or components into the structure design is one effective method, which, however, often introduces additional loss to the resonances, thus greatly affecting the efficiency of modulation. Here, we numerically propose a reflection-type dielectric metasurface design that could allow switchable and efficient wavefront control in the terahertz regime. The metasurfaces are composed of dielectric structures suspended on a ground metallic film, which can exhibit different phase responses at different gap distances between them owing to the variation of the Fabre-Pérot (FP) resonance. Two metasurfaces are designed and numerically demonstrated, which can achieve mechanically switchable beam steering and wave focusing responses, respectively, by only changing the gap distance by a small range of 1/3 working wavelength. The maximum efficiency can reach around 89%. The proposed method provides a new avenue towards efficient and active terahertz wavefront control.

Experimental Demonstration of Adaptive Optics Correction of the External Aberrations for Distributed Fiber Laser Array

A novel method of pre-compensating the phase distortions outside the fiber laser array based on active integrated wavefront sensing is proposed and demonstrated experimentally. The scheme and the working principle are introduced. Pre-compensation experiment of the fiber laser array based on a 7-element adaptive fiber optics collimator (AFOC) array with filled factor of 0.875 is presented. Residual error RMS of $0.11~\mu \text{m}$ is obtained while sensing lower order aberrations of a glass plate is with initial RMS of $0.62~\mu \text{m}$ . Metric of far-field power-in-the-bucket (PIB) is improved about 3.5 times after the phase distortions are pre-compensated. This method could promote the transmission efficiency of the fiber laser array in atmosphere, without limits of array scale and transmission light delay. This method would be upgraded to correct the aberrations located in the whole optical link from laser source to the target in the future. Such method would highly promote the applications of fiber laser array based systems like free space laser communication.

The road to atomically thin metasurface optics

AbstractThe development of flat optics has taken the world by storm. The initial mission was to try and replace conventional optical elements by thinner, lightweight equivalents. However, while developing this technology and learning about its strengths and limitations, researchers have identified a myriad of exciting new opportunities. It is therefore a great moment to explore where flat optics can really make a difference and what materials and building blocks are needed to make further progress. Building on its strengths, flat optics is bound to impact computational imaging, active wavefront manipulation, ultrafast spatiotemporal control of light, quantum communications, thermal emission management, novel display technologies, and sensing. In parallel with the development of flat optics, we have witnessed an incredible progress in the large-area synthesis and physical understanding of atomically thin, two-dimensional (2D) quantum materials. Given that these materials bring a wealth of unique physical properties and feature the same dimensionality as planar optical elements, they appear to have exactly what it takes to develop the next generation of high-performance flat optics.

Abstract 17013: Voltage Resolution of Standard Bipolar and Omnipolar Ventricular Electrograms

Introduction: Standard bipolar voltage (BiV) mapping is dependent on bipole axis orientation compared to the direction of the activation wavefront. In contrast, omnipolar mapping technology (OmniT) allows for direction-independent voltage measurement, yielding a maximum for each site sampled. However, it is unclear if normal voltage values are the same for BiV and OmniT. Hypothesis: To determine whether electrical signal obtained with OmniT are greater than BiV, using a single 4x4 grid array catheter (HD Grid) inserted in the left ventricle (LV) of an experimental animal. Methods: HD Grid consists of 4 splines, allowing for orthogonal bipoles along (AL) a single spline and across (AC) adjacent splines, allowing for simultaneous OmniT and BiV evaluation. Animals (n=3) underwent transseptal LV mapping during sinus rhythm (SR) and right ventricular pacing (RVP) using HD Grid (4mm interelectrode spacing). Abbott Precision research software was used to generate electroanatomic maps. Peak-to-peak voltage data for OmniT and BiV, both along and across the splines, were exported to a spreadsheet. Data were normalized via log transformation and compared with t-test. Results: Mean voltages and 95% confidence interval for OmniT were consistently greater than BiV AL and AC for both SR and RVP (p&lt;0.05), while BiV AL and AC were comparable. No difference was seen when comparing each method during SR and RVP. The absolute BiV difference due to orientation was significant. See Table. Conclusions: Amplitude of OmiT electorgrams are greater with respect to BiV, which is consistent with the ability of omnipolar technology to capture maximal signals independently from waveform direction. This should be taken into account when determining the optimal OmniT value for ventricular scar.

Ventricular transmural decremental conduction explains short t-peak-t-end interval in “in silico” ECG reconstruction model

Abstract Introduction In chronic hepatic cirrhosis (CHC), T-wave peak to T-wave end interval (TPTE) has shown prognostic value for survival and liver transplantation. Altered cellular ionic regulatory systems may produce decremental conduction in ventricular endocardial to epicardial activation wavefront propagation and ECG waveforms, particularly the T-wave. It was investigated whether ventricular transmural activation wavefront conduction may affect T-wave shape and impact TPTE duration, using “in silico” ECG reconstruction. Methods Mammalian-derived ventricular endocardial to epicardial AP waveforms (APW) were simulated and deployed in 10 discrete layers in homogeneous impedance ventricular wedge-like model. A uniform conduction model was employed to mimic normal heart, in which the speed of propagation of the activation wavefront was nonzero and constant in all layers. In CHC heart, a decremental conduction model was employed, in which the speed of propagation of the activation wavefront was maximal at the endocardial layer and exponentially decayed to greater than zero speed at the epicardial layer. ECG was computed as the sum of dipoles weighted by the inverse of the squared distance to an observation electrode arbitrarily located outside the wedge. One dipole was one layer thick, and its charge was assumed as the time-integral of the current generated by the difference of potential between adjacent APW, from endocardial to epicardial layers. ECG was reconstructed in one axis. Results Two-dimensional transmural APW distribution and respective reconstructed ECGs are presented in Figures 1 and 2. In uniform endocardial to epicardial transmural conduction model, QRS complex was taller and shorter as well as TPTE was larger (Fig. 1) than respective counterparts in decremental conduction model (Fig. 2). Additionally, peak-amplitude of the T-wave as well as the maximal slope of the TPTE were lower in decremental as compared to uniform conduction model. Conclusion Using “in silico” ECG reconstruction, decrementally conducted model of epicardial to endocardial ventricular transmural activation wavefront propagation yields wider and lower amplitude QRS complex as well as shorter TPTE, as compared to respective counterparts in uniformly conducted activation wavefront model. Ventricular transmural decremental conduction model offers an insight into electrophysiological background of ECG findings in CHC. (NCT01433848) Transmural APW distribution vs ECG Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): Universidade do Estado do Rio de Janeiro; Rio de Janeiro, RJ - Brazil

His bundle lead placement: Is His bundle captured?

A 59-year-old female underwent a dual-chamber pacemaker implantation for intermittent complete heart block. A baseline electrocardiogram showed normal sinus rhythm with first-degree atrioventricular (AV) block and right bundle branch block. A His bundle lead placement was attempted. An intracardiac electrogram from the His bundle lead demonstrated atrial-His, and His-ventricular intervals were 186 and 110 ms, respectively. Pacing was performed from the His bundle lead with a decremental pacing output to assess for the His bundle capture threshold. However, there were no significant QRS morphology changes during the pacing. Is the His bundle captured? The tracing evaluation demonstrated the fascinating physiology of activation wavefront in His Purkinje system that could be applied in the use of conducting system pacing technologies.

Slow uniform electrical activation during sinus rhythm is an indicator of reentrant VT isthmus location and orientation in an experimental model of myocardial infarction

BackgroundTo validate the predictability of reentrant circuit isthmus locations without ventricular tachycardia (VT) induction during high-definition mapping, we used computer methods to analyse sinus rhythm activation in experiments where isthmus location was subsequently verified by mapping reentrant VT circuits. MethodIn 21 experiments using a canine postinfarction model, bipolar electrograms were obtained from 196-312 recordings with 4mm spacing in the epicardial border zone during sinus rhythm and during VT. From computerized electrical activation maps of the reentrant circuit, areas of conduction block were determined and the isthmus was localized. A linear regression was computed at three different locations about the reentry isthmus using sinus rhythm electrogram activation data. From the regression analysis, the uniformity, a measure of the constancy at which the wavefront propagates, and the activation gradient, a measure that may approximate wavefront speed, were computed. The purpose was to test the hypothesis that the isthmus locates in a region of slow uniform activation bounded by areas of electrical discontinuity. ResultsBased on the regression parameters, sinus rhythm activation along the isthmus near its exit proceeded uniformly (mean r2= 0.95±0.05) and with a low magnitude gradient (mean 0.37±0.10mm/ms). Perpendicular to the isthmus long-axis across its boundaries, the activation wavefront propagated much less uniformly (mean r2= 0.76±0.24) although of similar gradient (mean 0.38±0.23mm/ms). In the opposite direction from the exit, at the isthmus entrance, there was also less uniformity (mean r2= 0.80±0.22) but a larger magnitude gradient (mean 0.50±0.25mm/ms). A theoretical ablation line drawn perpendicular to the last sinus rhythm activation site along the isthmus long-axis was predicted to prevent VT reinduction. Anatomical conduction block occurred in 7/21 experiments, but comprised only small portions of the isthmus lateral boundaries; thus detection of sinus rhythm conduction block alone was insufficient to entirely define the VT isthmus. ConclusionsUniform activation with a low magnitude gradient during sinus rhythm is present at the VT isthmus exit location but there is less uniformity across the isthmus lateral boundaries and at isthmus entrance locations. These factors may be useful to verify any proposed VT isthmus location, reducing the need for VT induction to ablate the isthmus. Measured computerized values similar to those determined herein could therefore be assistive to sharpen specificity when applying sinus rhythm mapping to localize EP catheter ablation sites.

Endocardial-Epicardial Phase Mapping of Prolonged Persistent Atrial Fibrillation Recordings: High Prevalence of Dissociated Activation Patterns.

Endocardial-epicardial dissociation and focal breakthroughs in humans with atrial fibrillation (AF) have been recently demonstrated using activation mapping of short 10-second AF segments. In the current study, we used simultaneous endo-epi phase mapping to characterize endo-epi activation patterns on long segments of human persistent AF. Simultaneous intraoperative mapping of endo- and epicardial lateral right atrium wall was performed in patients with persistent AF using 2 high-density grid catheters (16 electrodes, 3 mm spacing). Filtered unipolar and bipolar electrograms of continuous 2-minute AF recordings and electrodes locations were exported for phase analyses. We defined endocardial-epicardial dissociation as phase difference of ≥20 ms between paired endo-epi electrodes. Wavefronts were classified as rotations, single wavefronts, focal waves, or disorganized activity as per standard criteria. Endo-Epi wavefront patterns were simultaneously compared on dynamic phase maps. Complex fractionated electrograms were defined as bipolar electrograms with ≥5 directional changes occupying at least 70% of sample duration. Fourteen patients with persistent AF undergoing cardiac surgery were included. Endocardial-epicardial dissociation was seen in 50.3% of phase maps with significant temporal heterogeneity. Disorganized activity (Endo: 41.3% versus Epi: 46.8%, P=0.0194) and single wavefronts (Endo: 31.3% versus Epi: 28.1%, P=0.129) were the dominant patterns. Transient rotations (Endo: 22% versus Epi: 19.2%, P=0.169; mean duration: 590±140 ms) and nonsustained focal waves (Endo: 1.2% versus Epi: 1.6%, P=0.669) were also observed. Apparent transmural migration of rotational activations (n=6) from the epi- to the endocardium was seen in 2 patients. Electrogram fractionation was significantly higher in the epicardium than endocardium (61.2% versus 51.6%, P<0.0001). Simultaneous endo-epi phase mapping of prolonged human persistent AF recordings shows significant Endocardial-epicardial dissociation marked temporal heterogeneity, discordant and transitioning wavefronts patterns and complex fractionations. No sustained focal activity was observed. Such complex 3-dimensional interactions provide insight into why endocardial mapping alone may not fully characterize the AF mechanism and why endocardial ablation may not be sufficient. Graphic Abstract: A graphic abstract is available for this article.

Creation of sinus rhythm and paced maps using a single acquisition step: the "one acquisition-two maps" technique-a feasibility study.

Scars and abnormal electrograms may significantly differ according to the activation wavefront. We propose a new fast technique for reliable comparison between sinus rhythm and ventricular pacing using a single map acquisition and the Rhythmia™ 3D mapping system. A special programming of the external stimulator was assuring full stable regular paced-beat bigeminy during spontaneous rhythm. A first map was acquired for the spontaneous cardiac beat. Then the window of detection was moved to the following paced beat, and a second map was available after recalculation by the system, depicting activation and voltage of the paced cardiac beat at the same locations, with an exactly the same number of beats in both maps. Thirty patients with structural heart disease referred for ablation of ventricular tachycardia underwent this protocol, who were compared with 19 similar patients undergoing repeated maps. Duration of the mapping was significantly shorter compared to controls (34±12 vs 57±14min, p< 0.0001) without differences in the number of electrograms (6978±7067 vs 9554±4424 for sinus rhythm map and 6610±7240 vs 7783±3804 for paced map, p= ns for both). The technique cannot be completed in five patients (17%), because of arrhythmogenicity, mechanical right bundle branch block, hemodynamical impairment, or bradycardia. We propose a novel technique for performing maps during sinus rhythm and ventricular pacing using a single acquisition. Beside time saving, this will allow more strict comparisons between different activation wavefronts.

High-power 7.4W TEM00 and wavelength-tunable alexandrite laser with a novel cavity design and efficient fibre-coupled diode-pumping

We report significant improvement in the performance of TEM00 alexandrite laser operation by employing high power fibre-coupled red diode pumping, novel cavity design, and active direct Shack-Hartmann wavefront sensor measurement of pump-induced lensing. We demonstrate 12.7 W of laser power in low-order ( M 2 ∼ 5 ) mode operation from a compact double-end-pumped cavity, and with novel cavity design, a record power of 7.4 W in TEM00 operation with excellent beam quality ( M 2 ≤ 1.1 ). With single-end pumping, laser power of 4.7 W ( M 2 ∼ 1.3 ) was achieved with slope efficiencies as high as 54.9 %; a record efficiency for red-diode-pumped alexandrite. Using a birefringent filter, continuous laser wavelength tuning from 725-808 nm is achieved in diffraction-limited TEM00 mode, with laser power of 4.7 W at 765 nm, and &gt;1 W across 730-805 nm, which is a higher tunable power than any other directly diode-pumped vibronic laser, to the best of our knowledge.

Impact of interventricular delay on repolarization parameters in patients with biventricular pacing

A 48-year-old man who was previously a responder to cardiac resynchronization therapy (CRT) presented with worsening of heart failure and reduction in the percentage biventricular (BiV) pacing. Device interrogation revealed T-wave oversensing that was eliminated by optimizing the interventricular (VV) delay. Compared to simultaneous BiV pacing, both sequential left ventricle-right ventricle (LV-RV) and univentricular LV pacing shortened the QTc, T peak-end intervals and reduced the T wave amplitude. Modification of VV delays can result in changes in wavefront of activation and thereby affect ventricular repolarization patterns.

2019 APHRS expert consensus statement on three-dimensional mapping systems for tachycardia developed in collaboration with HRS, EHRA, and LAHRS.

2019 APHRS expert consensus statement on three-dimensional mapping systems for tachycardia developed in collaboration with HRS, EHRA, and LAHRS.