Publications by authors named "Marc Strik"

38 Publications

Left axis deviation in patients with non-ischemic heart failure and left bundle branch block is a purely electrical phenomenon.

Heart Rhythm 2021 Apr 5. Epub 2021 Apr 5.

Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, 33600 Pessac-Bordeaux, France; IHU Liryc, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, F-33600 Pessac-Bordeaux, France.

Background: Possible mechanisms of left axis deviation (LAD) in the setting of left bundle branch block (LBBB) include differences in cardiac electrophysiology, structure, or anatomical axis.

Objectives: We sought to clarify the mechanism(s) responsible for LAD in patients with LBBB.

Methods: Twenty-nine patients with non-ischemic cardiomyopathies and LBBB underwent non-invasive electrocardiographic mapping (ECGi), cardiac computed tomography, and magnetic resonance imaging in order to define ventricular electrical activation, characterize cardiac structure, and determine the heart anatomical axis.

Results: Sixteen patients had a normal QRS axis (NA, mean axis: 8±23°) whereas 13 patients had LAD (mean axis: -48±13°, p<0.001). Total activation times were longer in the LAD group (112±25 vs 91±14ms, p=0,01) due to delayed activation of the basal anterolateral region (107±10 vs 81±17ms, p<0.001). Left ventricular (LV) activation in patients with LAD was from apex-to-base, contrasting with a circumferential pattern of activation in patients with NA. The apex-to-base delay was therefore longer in the LA group (95±13 vs 64±21ms, p<0.001) and correlated with the QRS frontal axis (R=0,67, p<0.001). Both groups were comparable in LV end diastolic volume (295±84vs LAD: 310±91ml; p=0.69), LV mass (177±33 vs LAD: 180±37g, p=0.83) and anatomical axis.

Conclusion: Left axis deviation in left bundle branch block appears to be due to electrophysiological abnormalities rather than structural factors or the cardiac anatomical axis.
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http://dx.doi.org/10.1016/j.hrthm.2021.03.042DOI Listing
April 2021

Accuracy of a Smartwatch-Derived ECG for Diagnosing Bradyarrhythmias, Tachyarrhythmias, and Cardiac Ischemia.

Circ Arrhythm Electrophysiol 2021 01 14;14(1):e009260. Epub 2021 Jan 14.

Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, F-33600 Pessac, France (T.C., H.M., S.B., N.W., S.P., M.H., P.B.).

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http://dx.doi.org/10.1161/CIRCEP.120.009260DOI Listing
January 2021

Progressive implantable cardioverter-defibrillator therapies for ventricular tachycardia: The efficacy and safety of multiple bursts, ramps, and low-energy shocks.

Heart Rhythm 2020 12 30;17(12):2072-2077. Epub 2020 Jul 30.

Cardio-Thoracic Unit, Bordeaux University Hospital (CHU), Pessac, France; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France.

Background: The Heart Rhythm Society, the European Heart Rhythm Association, the Asia Pacific Heart Rhythm Society, the Latin American Heart Rhythm Society expert consensus statement on optimal implantable cardioverter-defibrillator programming recommends burst antitachycardia pacing (ATP) for the treatment of ventricular tachycardia (VT) up to high rates. The number of bursts is not specified, and treatment by ramps or low-energy shocks is not recommended.

Objectives: We investigated the efficacy and safety of progressive therapies for VTs between 150 and 200 beats/min. After 3 failed bursts, we compared 3 ramps vs 3 bursts followed by a low-energy shock vs high-energy shock.

Methods: Using remote monitoring, we included monomorphic VT episodes treated with ≥1 burst.

Results: A total of 1126 VT episodes were included. A single burst was as likely to terminate VT between 150 and 200 beats/min as VT between 200 and 230 beats/min (63% vs 64%; P=.41), but was more likely to accelerate the latter (3.2% vs 0.25%; P<.01). For VT <200 beats/min, the likelihood of ATP success increased progressively (73% with 2 bursts, 78% with 3 bursts). Three additional bursts further increased VT termination to 89%, similar to the success rate with 3 additional ramps (88%; P=.17). Programming 6 bursts is associated with the probability of acceleration requiring shock of 6.6%. A low-energy first shock was less successful than a high-energy shock (66% vs 86%; P<.01) and more likely to accelerate VT (17% vs 0%; P<.01).

Conclusion: Programming up to 6 burst ATP therapies for VTs 150-200 beats/min can avoid implantable cardioverter-defibrillator shocks in most patients. Ramp ATP after failed bursts were similarly effective. Low-energy shocks are less effective and more arrhythmogenic than high-energy shocks.
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http://dx.doi.org/10.1016/j.hrthm.2020.07.032DOI Listing
December 2020

Should we still monitor QTc duration in frail older patients on low-dose haloperidol? A prospective observational cohort study.

Age Ageing 2020 08;49(5):829-836

Cardiology Department, Maastricht University Medical Centre, Maastricht 6229 HX, The Netherlands.

Background: Haloperidol at high dosage is associated with QTc prolongation and polymorphic ventricular arrhythmia but the effects of low-dose haloperidol remain unknown.

Objective: To evaluate the effects of low-dose haloperidol on QTc-duration in frail hospitalized elderly patients with delirium.

Methods: A prospective observational study including hospitalized patients aged ≥70 years with Groningen Frailty Index-score > 3. We included 150 patients who received haloperidol and 150 age- and frailty-matched control patients. Serial ECG recordings were performed at hospital admission and during hospitalization. QT-interval was corrected according to Framingham (QTc). Patients were grouped according to baseline QTc in normal (nQTc), borderline (bQTc) or abnormal (aQTc). Primary outcome was change in QTc-duration between first and second ECG. Potentially dangerous QTc was defined as QTc >500 ms or an increase of >50 ms.

Results: Patients in the haloperidol group (48% male, mean age 85y, nQT n = 98, bQT n = 31, aQT n = 20) received an average dose of 1.5 mg haloperidol per 24 hours. QTc decreased in patients with borderline (mean - 15 ± 29 ms, P < 0.05) or abnormal (-19 ± 27 ms, P < 0.05) QTc at baseline, no patients developed dangerous QTc-duration. In the control group (41% male, mean age 84y, nQT n = 99 bQT n = 29, aQT n = 22) QTc decreased to a similar extent (bQT -7 ± 16 ms, aQTc -23 ± 20 ms).

Conclusion: A trend to QTc shortening was seen, especially in patients with borderline or abnormal QTc at baseline, regardless of haloperidol use. These findings suggest that ECG monitoring of frail elderly patients who receive low-dose haloperidol, may not be necessary.
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http://dx.doi.org/10.1093/ageing/afaa066DOI Listing
August 2020

Validating QT-Interval Measurement Using the Apple Watch ECG to Enable Remote Monitoring During the COVID-19 Pandemic.

Circulation 2020 07 1;142(4):416-418. Epub 2020 Jun 1.

Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, Pessac, France (M.S., T.C., F.D.R., S.A.-A., H.M., N.W., P.R., M.H., S.P., P.B.).

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http://dx.doi.org/10.1161/CIRCULATIONAHA.120.048253DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7382529PMC
July 2020

Electrogram morphology discriminators in implantable cardioverter defibrillators: A comparative evaluation.

J Cardiovasc Electrophysiol 2020 06 7;31(6):1493-1506. Epub 2020 May 7.

Cardio-Thoracic Unit, Bordeaux University Hospital (CHU), Pessac, France.

Background: Morphology algorithms are currently recommended as a standalone discriminator in single-chamber implantable cardioverter defibrillators (ICDs). However, these proprietary algorithms differ in both design and nominal programming.

Objective: To compare three different algorithms with nominal versus advanced programming in their ability to discriminate between ventricular (VT) and supraventricular tachycardia (SVT).

Methods: In nine European centers, VT and SVTs were collected from Abbott, Boston Scientific, and Medtronic dual- and triple-chamber ICDs via their respective remote monitoring portals. Percentage morphology matches were recorded for selected episodes which were classified as VT or SVT by means of atrioventricular comparison. The sensitivity and related specificity of each manufacturer discriminator was determined at various values of template match percentage from receiving operating characteristics (ROC) curve analysis.

Results: A total of 534 episodes were retained for the analysis. In ROC analyses, Abbott Far Field MD (area under the curve [AUC]: 0.91; P < .001) and Boston Scientific RhythmID (AUC: 0.95; P < .001) show higher AUC than Medtronic Wavelet (AUC: 0.81; P < .001) when tested for their ability to discriminate VT from SVT. At nominal % match threshold all devices provided high sensitivity in VT identification, (91%, 100%, and 90%, respectively, for Abbott, Boston Scientific, and Medtronic) but contrasted specificities in SVT discrimination (85%, 41%, and 62%, respectively). Abbott and Medtronic's nominal thresholds were similar to the optimal thresholds. Optimization of the % match threshold improved the Boston Scientific specificity to 79% without compromising the sensitivity.

Conclusion: Proprietary morphology discriminators show important differences in their ability to discriminate SVT. How much this impact the overall discrimination process remains to be investigated.
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http://dx.doi.org/10.1111/jce.14518DOI Listing
June 2020

Oversensing issues leading to device extraction: When subcutaneous implantable cardioverter-defibrillator reached a dead-end.

Heart Rhythm 2020 01 8;17(1):66-74. Epub 2019 Jul 8.

Bordeaux University Hospital, Cardio-Thoracic Unit, Pessac, France; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac - Bordeaux, France.

Background: Subcutaneous implantable cardioverter-defibrillator (S-ICD) implantations are rapidly expanding. However, the subcutaneous detection and interpretation of cardiac signals in S-ICDs is much more challenging than by conventional devices. There is a complete paradigm shift in cardiac signal sensing with subcutaneous signal detection, leading in some cases to oversensing with restricted programming options.

Objectives: The aim of this single-center study was to quantify and describe cases where recurring oversensing made the extraction of the device necessary.

Methods: Consecutive patients (n = 108) implanted with an S-ICD in our tertiary referral hospital were considered for analysis. Clinical and remote monitoring data were analyzed.

Results: The S-ICD had to be explanted in 6 of 108 implanted patients (5.6%) because of refractory oversensing issues: myopotential oversensing, P- or T-wave oversensing, rate-dependent left bundle branch block aberrancy during exercise with R-wave double counting, and R-wave amplitude decrease after ventricular tachycardia ablation leading to noise detection. Seventeen of 108 patients experienced oversensing (15.7%): 9 patients had at least 1 inappropriate charge without a shock (8.3%), 3 patients had at least 1 inappropriate shock (2.8%), and 5 patients had both episodes (4.6%).

Conclusion: So far, cardiologists have had to deal with transvenous ICD lead fractures, but signal oversensing without correcting programming option could be the equivalent weakness of S-ICDs, despite an adequate screening.
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http://dx.doi.org/10.1016/j.hrthm.2019.07.004DOI Listing
January 2020

Non-invasive cardiac mapping for non-response in cardiac resynchronization therapy.

Ann Med 2019 03 23;51(2):109-117. Epub 2019 May 23.

a IHU Liryc , Electrophysiology and Heart Modeling Institute , Bordeaux , France.

Cardiac resynchronization therapy (CRT) is an effective intervention in selected patients with moderate-to-severe heart failure with reduced ejection fraction and abnormal left ventricular activation time. The non-response rate of approximately 30% has remained nearly unchanged since this therapy was introduced 25 years ago. While intracardiac mapping is widely used for diagnosis and guidance of therapy in patients with tachyarrhythmia, its application in characterization of the electrical substrate to elucidate the mechanisms involved in CRT response remain anecdotal. In the present review, we describe the traditional determinants of CRT response before presenting novel non-invasive techniques used for CRT optimization. We discuss efforts to identify the target electrical substrate to guide the deployment of pacing electrodes during the operative procedure. Non-invasive body surface mapping technologies such as ECG imaging or ECG belt enables prediction of acute and chronic CRT response. While electrical dyssynchrony parameters provide high predictive accuracy for CRT response when obtained during intrinsic conduction, their predictive value is less when acquired during CRT or LV-pacing. Key messages Classic predictors of CRT response are female gender, NYHA class ≤ III, left ventricular ejection fraction ≥25%, QRS duration ≥150 ms and estimated glomerular filtration rate ≥60 mL/min. ECG-imaging is a comprehensive non-invasive mapping system which allows to express the amount of electrical asynchrony of a CRT candidate. Non-invasive body surface mapping technologies enables excellent prediction of acute and chronic CRT response before implantation. When performed during CRT or LV-pacing, the added value of these mapping systems remains unclear.
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http://dx.doi.org/10.1080/07853890.2019.1616109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7857455PMC
March 2019

Echocardiographic Assessment of Left Bundle Branch-Related Strain Dyssynchrony: A Comparison With Tagged MRI.

Ultrasound Med Biol 2019 08 3;45(8):2063-2074. Epub 2019 May 3.

Cardiovascular Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.

Recent studies have shown the efficacy of myocardial strain estimated using speckle tracking echocardiography (STE) in predicting response to cardiac resynchronisation therapy. This study focuses on circumferential strain patterns, comparing STE-acquired strains to tagged-magnetic resonance imaging (MRI-T). Second, the effect of regularisation was examined. Two-dimensional parasternal ultrasound (US) and MRI-T data were acquired in the left ventricular short-axis view of canines before (n = 8) and after (n = 9) left bunch branch block (LBBB) induction. US-based strain analysis was performed on Digital Imaging and Communications in Medicine data at the mid-level using three overall methods ("Commercial software," "Basic block-matching," "regularised block-matching"). Moreover, three regularisation approaches were implemented and compared. MRI-T analysis was performed using SinMod. Normalised regional circumferential strain curves, based on standard six or septal/lateral segments, were analysed and cross-correlated with MRI-T data. Systolic strain (SS) and septal rebound stretch (SRS) were calculated and compared. Overall agreement of normalised circumferential strain was good between all methods on a global and regional level. All STE methods showed a bias (≥4% strain) toward higher SS estimates. Pre-LBBB, septal and lateral segment correlation was excellent between the Basic (mean ρ = 0.96) and regularised (mean ρ = 0.97) methods and MRI-T. The Commercial method showed a significant discrepancy between the two walls (septal ρ = 0.94, lateral ρ = 0.68). Correlation with MRI-T reduced between pre- and post-LBBB (Commercial ρ = 0.79, Basic ρ = 0.82, mean regularised ρ = 0.86). Septal strain patterns and SRS varied with the STE software and type of regularisation, with all STE methods estimating non-zero SRS values pre-LBBB. Absolute values showed moderate agreement, with a bias for higher strain from STE. SRS varied with the type of software and extra regularisation applied. Open efforts are needed to understand the underlying causes of differences between STE methods before standardisation can be achieved. This is particularly important given the apparent clinical value of strain-based parameters such as SRS.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2019.03.012DOI Listing
August 2019

The Left and Right Ventricles Respond Differently to Variation of Pacing Delays in Cardiac Resynchronization Therapy: A Combined Experimental- Computational Approach.

Front Physiol 2019 1;10:17. Epub 2019 Feb 1.

Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, Netherlands.

Timing of atrial, right (RV), and left ventricular (LV) stimulation in cardiac resynchronization therapy (CRT) is known to affect electrical activation and pump function of the LV. In this study, we used computer simulations, with input from animal experiments, to investigate the effect of varying pacing delays on both LV and RV electrical dyssynchrony and contractile function. A pacing protocol was performed in dogs with atrioventricular block ( = 6), using 100 different combinations of atrial (A)-LV and A-RV pacing delays. Regional LV and RV electrical activation times were measured using 112 electrodes and LV and RV pressures were measured with catheter-tip micromanometers. Contractile response to a pacing delay was defined as relative change of the maximum rate of LV and RV pressure rise (dP/dt) compared to RV pacing with an A-RV delay of 125 ms. The pacing protocol was simulated in the CircAdapt model of cardiovascular system dynamics, using the experimentally acquired electrical mapping data as input. Ventricular electrical activation changed with changes in the amount of LV or RV pre-excitation. The resulting changes in dP/dt differed markedly between the LV and RV. Pacing the LV 10-50 ms before the RV led to the largest increases in LV dP/dt. In contrast, RV dP/dt was highest with RV pre-excitation and decreased up to 33% with LV pre-excitation. These opposite patterns of changes in RV and LV dP/dt were reproduced by the simulations. The simulations extended these observations by showing that changes in steady-state biventricular cardiac output differed from changes in both LV and RV dP/dt. The model allowed to explain the discrepant changes in dP/dt and cardiac output by coupling between atria and ventricles as well as between the ventricles. The LV and the RV respond in a opposite manner to variation in the amount of LV or RV pre-excitation. Computer simulations capture LV and RV behavior during pacing delay variation and may be used in the design of new CRT optimization studies.
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http://dx.doi.org/10.3389/fphys.2019.00017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6367498PMC
February 2019

Unsuccessful antitachycardia pacing: What is the mechanism?

Pacing Clin Electrophysiol 2019 Apr 21;42(4):464-466. Epub 2019 Feb 21.

Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands.

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http://dx.doi.org/10.1111/pace.13625DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6849796PMC
April 2019

Integration of cardiac magnetic resonance imaging, electrocardiographic imaging, and coronary venous computed tomography angiography for guidance of left ventricular lead positioning.

Europace 2019 Apr;21(4):626-635

Department of Cardiology, CARIM, Maastricht University Medical Center, Maastricht, the Netherlands.

Aims: An appropriate left ventricular (LV) lead position is a pre-requisite for response to cardiac resynchronization therapy (CRT) and is highly patient-specific. The purpose of this study was to develop a non-invasive pre-procedural CRT-roadmap to guide LV lead placement to a coronary vein in late-activated myocardium remote from scar.

Methods And Results: Sixteen CRT candidates were prospectively included. Electrocardiographic imaging (ECGI), computed tomography angiography (CTA), and delayed enhancement cardiac magnetic resonance imaging (DE-CMR) were integrated into a 3D cardiac model (CRT-roadmap) using anatomic landmarks from CTA and DE-CMR. Electrocardiographic imaging was performed using 184 electrodes and a CT-based heart-torso geometry. Coronary venous anatomy was visualized using a designated CTA protocol. Focal scar was assessed from DE-CMR. Cardiac resynchronization therapy-roadmaps were constructed for all 16 patients [left bundle branch block: n = 6; intraventricular conduction disturbance: n = 8; narrow-QRS (ablate and pace strategy); n = 1; right bundle branch block: n = 1]. The number of coronary veins ranged between 3 and 4 per patient. The CRT-roadmaps showed no (n = 5), 1 (n = 6), or 2 (n = 5) veins per patient located outside scar in late-activated myocardium [≥50% QRS duration (QRSd)]. Final LV lead position was outside scar in late-activated myocardium in 11 out of 14 implanted patients, while a LV lead in scar was unavoidable in the remaining three patients.

Conclusion: A non-invasive pre-implantation CRT-roadmap was feasible to develop in a case series by integration of coronary venous anatomy, myocardial-scar localization, and epicardial electrical activation patterns, anticipating on clinically relevant features.
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http://dx.doi.org/10.1093/europace/euy292DOI Listing
April 2019

Inappropriate disabling of an ICD noise-detection algorithm in pacemaker-dependent patients.

Pacing Clin Electrophysiol 2019 Apr 12;42(4):478-482. Epub 2018 Dec 12.

Cardio-thoracic Unit, Bordeaux University Hospital (CHU), Pessac, France.

SecureSense is an implantable cardioverter defibrillator algorithm that differentiates lead-related oversensing from ventricular tachycardia/ventricular fibrillation by continuous comparison between the near-field (NF) and the far-field (FF) electrogram. If lead noise is identified, inappropriate therapy is withheld. Undersensing on the FF channel could result in inappropriate inhibition of life-saving therapy. Thus, the device automatically switches SecureSense to passive mode if undersensing on the FF channel is suspected. We report here the first cases of inappropriate automatic SecureSense deactivation due to misdiagnosed FF undersensing in pacemaker-dependent patients. Physicians should be aware that SecureSense does not withhold an inappropriate therapy for sustained oversensing in pacemaker-dependent patients.
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http://dx.doi.org/10.1111/pace.13564DOI Listing
April 2019

Unexpected and undesired side-effects of pacing algorithms during exercise.

J Electrocardiol 2018 Nov - Dec;51(6):1023-1028. Epub 2018 Aug 17.

IHU Liryc, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, F-33600 Pessac-Bordeaux, France; Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, F-33600 Pessac, France.

While the implantable pacemaker has initially been developed to treat symptomatic bradycardia, we demand of modern devices that they also function properly during exercise. In recent years, device manufacturers have implemented multiple proprietary algorithms which aim to improve pacemaker function by avoiding unnecessary right ventricular pacing, optimizing atrial refractory periods and diagnosing pacemaker mediated tachycardia. When activated, these algorithms may save the associated EGM into the device memory which enables later analysis by remote monitoring or device interrogation. In addition, the performance of an exercise-test while analyzing the EGM, enables the verification of proper algorithm function, the evaluation of residual symptoms and the optimization of specific parameters that vary as a function of heart rate. In this manuscript, we demonstrate how pacemaker algorithms may induce dropped P-waves during exercise in pacemaker dependent patients and loss of biventricular pacing in CRT patients.
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http://dx.doi.org/10.1016/j.jelectrocard.2018.08.021DOI Listing
October 2019

Response to cardiac resynchronization therapy is determined by intrinsic electrical substrate rather than by its modification.

Int J Cardiol 2018 Nov 6;270:143-148. Epub 2018 Jun 6.

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600 Pessac, Bordeaux, France; Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, F-33600 Pessac, France.

Background: Electrocardiographic mapping (ECM) expresses electrical substrate through magnitude and direction of the activation delay vector (ADV). We investigated to what extent the response to cardiac resynchronization therapy (CRT) is determined by baseline ADV and by ADV modification through CRT and optimization of left ventricular (LV) pacing site.

Methods: ECM was performed in 79 heart failure patients (4 RBBB, 12 QRS < 120 ms, 23 non-specific conduction delay [NICD] and 40 left bundle branch block [LBBB]). 67 patients (QRS ≥ 120 ms) underwent CRT implantation and in 26 patients multiple LV pacing site optimization was performed. ADV was calculated from locations/depolarization times of 2000 virtual epicardial electrodes derived from ECM. Acute response was defined as ≥10% LVdP/dt increase, chronic response by composite clinical score at 6 months.

Results: During intrinsic conduction, ADV direction was similar in patients with QRS < 120 ms, NICD and LBBB, pointing towards the LV free wall, while ADV magnitude was larger in LBBB (117 ± 25 ms) than in NICD (70 ± 29 ms, P < 0.05) and QRS < 120 ms (52 ± 14 ms, P < 0.05). Intrinsic ADV accurately predicted the acute (AUC = 0.93) and chronic (AUC = 0.90) response to CRT. ADV change by CRT only moderately predicted response (highest AUC = 0.76). LV pacing site optimization had limited effects: +3 ± 4% LVdP/dt when compared to conventional basolateral LV pacing.

Conclusion: The baseline electrical substrate, adequately measured by ADV amplitude, strongly determines acute and chronic CRT response, while the extent of its modification by conventional CRT or by varying LV pacing sites has limited effects.
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http://dx.doi.org/10.1016/j.ijcard.2018.06.005DOI Listing
November 2018

Towards eradication of inappropriate therapies for ICD lead failure by combining comprehensive remote monitoring and lead noise alerts.

J Cardiovasc Electrophysiol 2018 08 22;29(8):1125-1134. Epub 2018 Jun 22.

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600, Pessac- Bordeaux, France.

Introduction: Recognition of implantable cardioverter defibrillator (ICD) lead malfunction before occurrence of life threatening complications is crucial. We aimed to assess the effectiveness of remote monitoring associated or not with a lead noise alert for early detection of ICD lead failure.

Methods: From October 2013 to April 2017, a median of 1,224 (578-1,958) ICD patients were remotely monitored with comprehensive analysis of all transmitted materials. ICD lead failure and subsequent device interventions were prospectively collected in patients with (RMLN) and without (RM) a lead noise alert (Abbott Secure Sense™ or Medtronic Lead Integrity Alert™) in their remote monitoring system.

Results: During a follow-up of 4,457 patient years, 64 lead failures were diagnosed. Sixty-one (95%) of the diagnoses were made before any clinical complication occurred. Inappropriate shocks were delivered in only one patient of each group (3%), with an annual rate of 0.04%. All high voltage conductor failures were identified remotely by a dedicated impedance alert in 10 patients. Pace-sense component failures were correctly identified by a dedicated alert in 77% (17 of 22) of the RMLN group versus 25% (8 of 32) of the RM group (P = 0.002). The absence of a lead noise alert was associated with a 16-fold increase in the likelihood of initiating either a shock or ATP (OR: 16.0, 95% CI 1.8-143.3; P = 0.01).

Conclusion: ICD remote monitoring with systematic review of all transmitted data is associated with a very low rate of inappropriate shocks related to lead failure. Dedicated noise alerts further reduce inappropriate detection of ventricular arrhythmias.
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http://dx.doi.org/10.1111/jce.13653DOI Listing
August 2018

Optimizing Implantable Cardioverter-Defibrillator Remote Monitoring: A Practical Guide.

JACC Clin Electrophysiol 2017 04 17;3(4):315-328. Epub 2017 Apr 17.

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac, Bordeaux, France; Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, Pessac, Bordeaux, France.

Remote monitoring (RM) receives a Class I: Level of Evidence: A recommendation for the follow-up of patients with implantable cardioverter-defibrillators, positioning the technology as standard of care. RM is often seen and sold as a plug-and-play technology, whereas fundamental differences exist in the philosophy and conception of the 5 main RM systems. The capabilities and limitations of the different RM systems need to be understood and taken into account when the decision is made to remotely manage an individual patient. The purpose of this review is to provide to the cardiologist practical information about RM systems' specificities with respect to the different technical and clinical alerts. Clinically based indications and programming suggestions are provided.
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http://dx.doi.org/10.1016/j.jacep.2017.02.007DOI Listing
April 2017

Too old to shock?: Questioning added benefit of ICD in elderly CRT patients.

Int J Cardiol 2018 07;263:65-66

Departments of Cardiology and Physiology, Cardiovascular Research Institute Maastricht (CARIM), P.O. Box 616, 6200 MD Maastricht, The Netherlands. Electronic address:

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http://dx.doi.org/10.1016/j.ijcard.2018.04.036DOI Listing
July 2018

Defibrillation testing is mandatory in patients with subcutaneous implantable cardioverter-defibrillator to confirm appropriate ventricular fibrillation detection.

Heart Rhythm 2018 05;15(5):642-650

Hospital Haut-Leveque, IHU LIRYC, Pessac, France.

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) remains a new technology requiring accurate assessment of the various aspects of its functioning. Isolated cases of delayed sensing of ventricular arrhythmia have been described.

Objective: The purpose of this multicenter study was to assess the quality of sensing during induced ventricular fibrillation (VF).

Methods: One hundred thirty-seven patients underwent induction of VF at the end of the S-ICD implantation.

Results: VF induction was successful in 133 patients (97%). Mean time to first therapy was 16.2 ± 3.1 seconds, with a substantial range from 12.5 to 27.0 seconds. Four different detection profiles were arbitrarily defined: (1) optimal detection (n = 39 [29%]); (2) undersensing with moderate prolongation of time to therapy (<18 seconds; n = 68 [51%]); (3) undersensing with significant prolongation of the time to therapy (>18 seconds; n = 19 [14%]); and (4) absence of therapy or prolonged time to therapy related to noise oversensing (n = 7 [6%]). In some of the patients in the last group, despite induction of VF the initial counter was never filled, the device did not charge the capacitors, and the shock was not delivered because of a sustained diagnosis of noise (n = 5). A manual shock by the device or an external shock had to be delivered to restore the sinus rhythm.

Conclusion: Our study demonstrated a marked sensing delay leading to prolonged time to therapy in a large number of S-ICD patients. A few worrisome cases of noise oversensing inhibiting the therapies were detected. These results support the need for systematic intraoperative defibrillation testing.
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http://dx.doi.org/10.1016/j.hrthm.2018.02.013DOI Listing
May 2018

Electrical Substrates Driving Response to Cardiac Resynchronization Therapy: A Combined Clinical-Computational Evaluation.

Circ Arrhythm Electrophysiol 2018 04;11(4):e005647

Electrophysiology and Heart Modeling Institute (LIRYC), Bordeaux University, Pessac, France (P.R.H., S.P., M.S., P.R., M.H., J.L., P.B.). Cardiac Electrophysiology and Cardiac Stimulation Team, Bordeaux University Hospital, Pessac, France (P.R.H., S.P., M.S., P.R., M.H., J.L., P.B.). Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Center, the Netherlands (P.R.H., M.S., J.W., F.W.P., T.D., J.L.).

Background: The predictive value of interventricular versus intraventricular dyssynchrony for response to cardiac resynchronization therapy (CRT) remains unclear. We investigated the relative importance of both ventricular electrical substrate components for left ventricular (LV) hemodynamic function.

Methods And Results: First, we used the cardiovascular computational model CircAdapt to characterize the isolated effect of intrinsic interventricular and intraventricular activation on CRT response (ΔLVdP/dt). Simulated ΔLVdP/dt (range: 1.3%-26.5%) increased considerably with increasing interventricular dyssynchrony. In contrast, the isolated effect of intraventricular dyssynchrony in either the LV or right ventricle was limited (ΔLVdP/dt range: 12.3%-18.3% and 14.1%-15.7%, respectively). Effects of activation during biventricular pacing on ΔLVdP/dt were small. Second, electrocardiographic imaging-derived activation characteristics of 51 CRT candidates were used to personalize ventricular activation in CircAdapt. The individualized models were subsequently used to assess the accuracy of ΔLVdP/dt prediction based on the electrical data. The model-predicted ΔLVdP/dt was close to the actual value in patients with left bundle branch block (measured-simulated: 2.7±9.0%) when only intrinsic interventricular dyssynchrony was personalized. Among patients without left bundle branch block, ΔLVdP/dt was systematically overpredicted by CircAdapt (measured-simulated: 9.2±7.1%). Adding intraventricular activation to the model did not improve the accuracy of the response prediction.

Conclusions: Computer simulations revealed that intrinsic interventricular dyssynchrony is the dominant component of the electrical substrate driving the response to CRT. Intrinsic intraventricular dyssynchrony and any dyssynchrony during biventricular pacing play a minor role in this respect. This may facilitate patient-specific modeling for prediction of CRT response.

Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01270646.
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http://dx.doi.org/10.1161/CIRCEP.117.005647DOI Listing
April 2018

Prediction of optimal cardiac resynchronization by vectors extracted from electrograms in dyssynchronous canine hearts.

J Cardiovasc Electrophysiol 2017 Aug 27;28(8):944-951. Epub 2017 Jun 27.

Department of Physiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands.

Introduction: Proper optimization of atrioventricular (AV) and interventricular (VV) intervals can improve the response to cardiac resynchronization therapy (CRT). It has been demonstrated that the area of the QRS complex (QRSarea) extracted from the vectorcardiogram can be used as a predictor of optimal CRT-device settings. We explored the possibility of extracting vectors from the electrograms (EGMs) obtained from pacing electrodes and of using these EGM-based vectors (EGMVs) to individually optimize acute hemodynamic CRT response.

Methods And Results: Biventricular pacing was performed in 13 dogs with left bundle branch block (LBBB) of which five also had myocardial infarction (MI), using 100 randomized AV- and VV-settings. Settings providing an acute increase in LV dP/dt ≥ 90% of the highest achieved value were defined as optimal. The prediction capability of QRSarea derived from the EGMV (EGMV-QRSarea) was compared with that of QRS duration. EGMV-QRSarea strongly correlated to the change in LV dP/dt (R = -0.73 ± 0.19 [LBBB] and -0.66 ± 0.14 [LBBB + MI]), while QRS duration was more poorly related to LV dP/dt changes (R = -0.33 ± 0.25 [LBBB] and -0.47 ± 0.39 [LBBB + MI]). This resulted in a better prediction of optimal CRT-device settings by EGMV-QRSarea than by QRS duration (LBBB: AUC = 0.89 [0.86-0.93] vs. 0.76 [0.69-0.83], P < 0.01; LBBB + MI: AUC = 0.91 [0.84-0.99] vs. 0.82 [0.59-1.00], P = 0.20, respectively).

Conclusion: In canine hearts with chronic LBBB with or without MI, the EGMV-QRSarea predicts acute hemodynamic CRT response and identifies optimal AV and VV settings accurately. These data support the potency of EGM-based vectors as a noninvasive, easy and patient-tailored tool to optimize CRT-device settings.
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http://dx.doi.org/10.1111/jce.13241DOI Listing
August 2017

Multicenter investigation of an implantable cardioverter-defibrillator algorithm to detect oversensing.

Heart Rhythm 2017 07 18;14(7):1008-1015. Epub 2017 Mar 18.

Haut-Lévêque Hospital, Centre Hospitalier Universitaire de Bordeaux, LIRYC Institute, Pessac, France.

Background: The SecureSense right ventricular (RV) lead noise discrimination algorithm is designed to detect lead fracture and other types of oversensing in order to decrease inappropriate therapy.

Objective: We studied the real-life accuracy of the SecureSense algorithm in implantable cardioverter-defibrillator (ICD) patients followed by remote monitoring across multiple centers.

Methods: Across 3 French centers, we studied 486 patients with a St Jude Medical device who were followed by remote monitoring and who had the SecureSense algorithm activated. We reviewed ≤10 of the most recent remote monitoring-transmitted electrograms of nonsustained oversensing, RV lead noise, and ventricular tachycardia/ventricular fibrillation that received therapy.

Results: SecureSense inhibited 22 inappropriate therapies (lead dysfunction in 10 cases, P-wave oversensing in 12 cases). A total of 57 patients (12%) sent ≥1 nonsustained oversensing episode (total of 393 episodes) with multiple etiologies: noise on the near-field channel (38%), oversensing of T waves during ventricular pacing (33%), oversensing of the sinus P wave (12%), and oversensing of the paced P wave (6%). Two episodes (0.5%) of nonsustained VT were undersensed by the far-field channel. Of 336 analyzed episodes of ventricular tachyarrhythmia, 15 episodes (4%) in 4 patients were related to oversensing of intrinsic P waves in 11 episodes or oversensing of external noise due to electrical cautery for the remaining 4 episodes.

Conclusion: Of ICD patients equipped with SecureSense, 12% developed episodes of oversensing. The SecureSense algorithm prevented inappropriate ICD therapies with accurate diagnosis of oversensing (caused by lead dysfunction or oversensing of physiological signals). P-wave oversensing in integrated bipolar leads, electrical cautery, and electromagnetic interference are prone to be missed by SecureSense.
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http://dx.doi.org/10.1016/j.hrthm.2017.03.023DOI Listing
July 2017

Assessment of left ventricular mechanical dyssynchrony in left bundle branch block canine model: Comparison between cine and tagged MRI.

J Magn Reson Imaging 2016 10 12;44(4):956-63. Epub 2016 Mar 12.

Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands.

Purpose: To compare cine and tagged magnetic resonance imaging (MRI) for left ventricular dyssynchrony assessment in left bundle branch block (LBBB), using the time-to-peak contraction timing, and a novel approach based on cross-correlation.

Materials And Methods: We evaluated a canine model dataset (n = 10) before (pre-LBBB) and after induction of isolated LBBB (post-LBBB). Multislice short-axis tagged and cine MRI images were acquired using a 1.5 T scanner. We computed contraction time maps by cross-correlation, based on the timing of radial wall motion and of circumferential strain. Finally, we estimated dyssynchrony as the standard deviation of the contraction time over the different regions of the myocardium.

Results: Induction of LBBB resulted in a significant increase in dyssynchrony (cine: 13.0 ± 3.9 msec for pre-LBBB, and 26.4 ± 5.0 msec for post-LBBB, P = 0.005; tagged: 17.1 ± 5.0 msec at for pre-LBBB, and 27.9 ± 9.8 msec for post-LBBB, P = 0.007). Dyssynchrony assessed by cine and tagged MRI were in agreement (r = 0.73, P = 0.0003); differences were in the order of time difference between successive frames of 20 msec (bias: -2.9 msec; limit of agreement: 10.1 msec). Contraction time maps were derived; agreement was found in the contraction patterns derived from cine and tagged MRI (mean difference in contraction time per segment: 3.6 ± 13.7 msec).

Conclusion: This study shows that the proposed method is able to quantify dyssynchrony after induced LBBB in an animal model. Cine-assessed dyssynchrony agreed with tagged-derived dyssynchrony, in terms of magnitude and spatial direction. J. MAGN. RESON. IMAGING 2016;44:956-963.
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http://dx.doi.org/10.1002/jmri.25225DOI Listing
October 2016

Performance of a specific algorithm to minimize right ventricular pacing: A multicenter study.

Heart Rhythm 2016 06 17;13(6):1266-73. Epub 2016 Feb 17.

Haut-Lévêque Hospital, Centre Hospitalier Universitaire de Bordeaux; LIRYC institute, Pessac, France.

Background: In Boston Scientific dual-chamber devices, the RYTHMIQ algorithm aims to minimize right ventricular pacing.

Objective: We evaluated the performance of this algorithm determining (1) the appropriateness of the switch from the AAI(R) mode with backup VVI pacing to the DDD(R) mode in case of suspected loss of atrioventricular (AV) conduction and (2) the rate of recorded pacemaker-mediated tachycardia (PMT) when AV hysteresis searches for restored AV conduction.

Methods: In this multicenter study, we included 157 patients with a Boston Scientific dual-chamber device (40 pacemakers and 117 implantable cardioverter-defibrillators) without permanent AV conduction disorder and with the RYTHMIQ algorithm activated. We reviewed the last 10 remote monitoring-transmitted RYTHMIQ and PMT episodes.

Results: We analyzed 1266 episodes of switch in 142 patients (90%): 207 (16%) were appropriate and corresponded to loss of AV conduction, and 1059 (84%) were inappropriate, of which 701 (66%) were related to compensatory pause (premature atrial contraction, 7%; premature ventricular contraction, 597 (56%); or both, 27 (3%)) or to a premature ventricular contraction falling in the post-atrial pacing ventricular refractory period interval (219, 21%) and 94 (10%) were related to pacemaker dysfunction. One hundred fifty-four PMT episodes were diagnosed in 27 patients (17%). In 85 (69%) of correctly diagnosed episodes, the onset of PMT was directly related to the algorithm-related prolongation of the AV delay, promoting AV dissociation and retrograde conduction.

Conclusion: This study highlights some of the limitations of the RYTHMIQ algorithm: high rate of inappropriate switch and high rate of induction of PMT. This may have clinical implications in terms of selection of patients and may suggest required changes in the algorithm architecture.
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http://dx.doi.org/10.1016/j.hrthm.2016.02.008DOI Listing
June 2016

Strategies to improve cardiac resynchronization therapy.

Nat Rev Cardiol 2014 Aug 20;11(8):481-93. Epub 2014 May 20.

Department of Physiology, Maastricht University, PO Box 616, 6200 MD Maastricht, Netherlands.

Cardiac resynchronization therapy (CRT) emerged 2 decades ago as a useful form of device therapy for heart failure associated with abnormal ventricular conduction, indicated by a wide QRS complex. In this Review, we present insights into how to achieve the greatest benefits with this pacemaker therapy. Outcomes from CRT can be improved by appropriate patient selection, careful positioning of right and left ventricular pacing electrodes, and optimal timing of electrode stimulation. Left bundle branch block (LBBB), which can be detected on an electrocardiogram, is the predominant substrate for CRT, and patients with this conduction abnormality yield the most benefit. However, other features, such as QRS morphology, mechanical dyssynchrony, myocardial scarring, and the aetiology of heart failure, might also determine the benefit of CRT. No single left ventricular pacing site suits all patients, but a late-activated site, during either the intrinsic LBBB rhythm or right ventricular pacing, should be selected. Positioning the lead inside a scarred region substantially impairs outcomes. Optimization of stimulation intervals improves cardiac pump function in the short term, but CRT procedures must become easier and more reliable, perhaps with the use of electrocardiographic measures, to improve long-term outcomes.
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http://dx.doi.org/10.1038/nrcardio.2014.67DOI Listing
August 2014

Electrophysiological and haemodynamic effects of vernakalant and flecainide in dyssynchronous canine hearts.

Europace 2014 Aug 30;16(8):1249-56. Epub 2014 Jan 30.

Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, PO Box 616, 6200 MD Maastricht, Limburg, The Netherlands.

Aims: About one-third of patients with mild dyssynchronous heart failure suffer from atrial fibrillation (AF). Drugs that convert AF to sinus rhythm may further slowdown ventricular conduction. We aimed to investigate the electrophysiological and haemodynamic effects of vernakalant and flecainide in a canine model of chronic left bundle branch block (LBBB).

Methods And Results: Left bundle branch block was induced in 12 canines. Four months later, vernakalant or flecainide was administered using a regime, designed to achieve clinically used plasma concentrations of the drugs, n = 6 for each drug. Epicardial electrical contact mapping showed that both drugs uniformly prolonged myocardial conduction time. Vernakalant increased QRS width significantly less than flecainide (17 ± 13 vs. 34 ± 15%, respectively). Nevertheless, both drugs equally decreased LVdP/dtmax by ∼15%, LVdP/dtmin by ∼10%, and left ventricular systolic blood pressure by ∼5% (P = n.s. between drugs).

Conclusions: Vernakalant prolongs ventricular conduction less than flecainide, but both drugs had a similar, moderate negative effect on ventricular contractility and relaxation. Part of these reductions seems to be related to the increase in dyssynchrony.
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http://dx.doi.org/10.1093/europace/eut429DOI Listing
August 2014

Acute electrical and hemodynamic effects of multisite left ventricular pacing for cardiac resynchronization therapy in the dyssynchronous canine heart.

Heart Rhythm 2014 Jan 9;11(1):119-25. Epub 2013 Oct 9.

Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.

Background: Multisite left ventricular (multi-LV) epicardial pacing has been proposed as an alternative to conventional single-site LV (single-LV) pacing to increase the efficacy of cardiac resynchronization therapy.

Objective: To compare the effects of multi-LV versus single-LV pacing in dogs with left bundle branch block (LBBB).

Methods: Studies were performed in 9 anaesthetized dogs with chronic LBBB using 7 LV epicardial electrodes. Each electrode was tested alone and in combination with 1, 2, 3, and 6 other electrodes, the sequence of which was chosen on the basis of practical real-time electrical mapping to determine the site of the latest activation. LV total activation time (LVTAT) and dispersion of repolarization (DRep) were measured by using approximately 100 electrodes around the ventricles. LV contractility was assessed as the maximum derivative of left ventricular pressure (LVdP/dtmax ).

Results: Single-LV pacing provided, on average, a -4.0% ± 9.3% change in LVTAT and 0.2% ± 13.7% change in DRep. Multi-LV pacing markedly decreased both LVTAT and DRep in a stepwise fashion to reach -41.3% ± 5% (P < .001 for overall comparison) and -14.2% ± 19.5% (P < .02 for overall comparison) in the septuple-LV pacing configuration, respectively. Single-LV pacing provided a mean increase of 10.7% ± 7.7% in LVdP/dtmax. LVdP/dtmax incrementally increased by the addition of pacing electrodes to 16.4% ± 8.7% (P < .001 for overall comparison). High response to single-LV pacing could not be improved further during multi-LV pacing.

Conclusions: Compared with single-LV pacing, multi-LV pacing can considerably reduce both LVTAT and DRep in dogs with LBBB, but the improvement in contractility is limited to conditions where single-LV pacing provides suboptimal improvement. Further studies are warranted to determine whether these acute effects translate in antiarrhythmic properties and better long-term outcomes.
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http://dx.doi.org/10.1016/j.hrthm.2013.10.018DOI Listing
January 2014

Electrophysiological and hemodynamic effects of vernakalant and flecainide during cardiac resynchronization in dyssynchronous canine hearts.

J Cardiovasc Pharmacol 2014 Jan;63(1):25-32

Departments of *Physiology; and †Cardiothoracic Surgery, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands; and ‡Division of Cardiology, Fondazione Cardiocentro Ticino, Lugano, Switzerland.

Introduction: Patients with heart failure and left bundle branch block (LBBB) are frequently treated with biventricular pacing (BiVP). Approximately one-third of them suffer from atrial fibrillation. Pharmacological conversion of atrial fibrillation is performed with drugs that slow ventricular conduction, but the effects of these drugs on the benefit of BiVP are poorly understood.

Methods: Experiments were performed in dogs with chronic LBBB, investigating the effects of Vernakalant and Flecainide (n = 6 each) on hemodynamics and electrophysiology during epicardial (EPI) and endocardial BiVP. The degree of dyssynchrony and conduction slowing was quantified using QRS width and EPI electrical mapping.

Results: Compared with LBBB, EPI and endocardial BiVP reduced QRS duration by 7% ± 9% (P < 0.05 compared with LBBB) and 20% ± 13% (P < 0.05 compared with LBBB, P < 0.05 between modes), respectively. During BiVP, the administration of Vernakalant and Flecainide increased QRS duration by 20% ± 14% (P < 0.05 compared with predrug BiVP) and 34% ± 10% (P < 0.05 compared with predrug BiVP, P < 0.05 between drugs). left ventricular (LV) dP/dtmax decreased by 16% ± 8% (P < 0.05 compared with predrug BiVP) during Vernakalant and by 14% ± 15% (P < 0.05 compared with predrug BiVP) during Flecainide. The drugs did not affect the relative changes in QRS width and LV dP/dtmax induced by BiVP.

Conclusions: Vernakalant and Flecainide decrease contractility, slow myocardial conduction velocity, and increase activation time. The electrical and hemodynamic benefits of BiVP are not altered by the drugs.
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http://dx.doi.org/10.1097/FJC.0000000000000020DOI Listing
January 2014

Interplay of electrical wavefronts as determinant of the response to cardiac resynchronization therapy in dyssynchronous canine hearts.

Circ Arrhythm Electrophysiol 2013 Oct 18;6(5):924-31. Epub 2013 Sep 18.

Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands.

Background: The relative contribution of electromechanical synchronization and ventricular filling to the optimal hemodynamic effect in cardiac resynchronization therapy (CRT) during adjustment of stimulation-timings is incompletely understood. We investigated whether optimal hemodynamic effect in CRT requires collision of pacing-induced and intrinsic activation waves and optimal filling of the left ventricle (LV).

Methods And Results: CRT was performed in dogs with chronic left bundle-branch block (n=8) or atrioventricular (AV) block (n=6) through atrial (A), right ventricular (RV) apex, and LV-basolateral pacing. A 100 randomized combinations of A-LV/A-RV intervals were tested. Total activation time (TAT) was calculated from >100 contact mapping electrodes. Mechanical interventricular dyssynchrony was determined as the time delay between upslopes of LV and RV pressure curves. Settings providing an increase in LVdP/dtmax (maximal rate of rise of left ventricular pressure) of ≥90% of the maximum LVdP/dtmax value were defined as optimal (CRTopt). Filling was assessed by changes in LV end-diastolic volume (EDV; conductance catheter technique). In all hearts, CRTopt was observed during multiple settings, providing an average LVdP/dtmax increase of ≈15%. In AV-block hearts, CRTopt exclusively depended on interventricular-interval and not on AV-interval. In left bundle-branch block hearts, CRTopt occurred at A-LV intervals that allowed fusion of LV-pacing-derived activation with right bundle-derived activation. In all animals, CRTopt occurred at settings resulting in the largest decrease in TAT and mechanical interventricular dyssynchrony, whereas LV EDV hardly changed.

Conclusions: In left bundle-branch block and AV-block hearts, optimal hemodynamic effect of CRT depends on optimal interplay between pacing-induced and intrinsic activation waves and the corresponding mechanical resynchronization rather than filling.
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http://dx.doi.org/10.1161/CIRCEP.113.000753DOI Listing
October 2013

Comparative electromechanical and hemodynamic effects of left ventricular and biventricular pacing in dyssynchronous heart failure: electrical resynchronization versus left-right ventricular interaction.

J Am Coll Cardiol 2013 Dec 4;62(25):2395-2403. Epub 2013 Sep 4.

Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, L'Institut de rythmologie et modélisation cardiaque (LIRYC), Université Bordeaux, Bordeaux, France.

Objectives: The purpose of this study was to enhance understanding of the working mechanism of cardiac resynchronization therapy by comparing animal experimental, clinical, and computational data on the hemodynamic and electromechanical consequences of left ventricular pacing (LVP) and biventricular pacing (BiVP).

Background: It is unclear why LVP and BiVP have comparative positive effects on hemodynamic function of patients with dyssynchronous heart failure.

Methods: Hemodynamic response to LVP and BiVP (% change in maximal rate of left ventricular pressure rise [LVdP/dtmax]) was measured in 6 dogs and 24 patients with heart failure and left bundle branch block followed by computer simulations of local myofiber mechanics during LVP and BiVP in the failing heart with left bundle branch block. Pacing-induced changes of electrical activation were measured in dogs using contact mapping and in patients using a noninvasive multielectrode electrocardiographic mapping technique.

Results: LVP and BiVP similarly increased LVdP/dtmax in dogs and in patients, but only BiVP significantly decreased electrical dyssynchrony. In the simulations, LVP and BiVP increased total ventricular myofiber work to the same extent. While the LVP-induced increase was entirely due to enhanced right ventricular (RV) myofiber work, the BiVP-induced increase was due to enhanced myofiber work of both the left ventricle (LV) and RV. Overall, LVdP/dtmax correlated better with total ventricular myofiber work than with LV or RV myofiber work alone.

Conclusions: Animal experimental, clinical, and computational data support the similarity of hemodynamic response to LVP and BiVP, despite differences in electrical dyssynchrony. The simulations provide the novel insight that, through ventricular interaction, the RV myocardium importantly contributes to the improvement in LV pump function induced by cardiac resynchronization therapy.
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http://dx.doi.org/10.1016/j.jacc.2013.08.715DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3985285PMC
December 2013