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Objectives: To study the safety and feasibility of a restrictive temporary-RV-pacemaker use and to evaluate the need for temporary pacemaker insertion for failed left ventricular (LV) pacing ability (no ventricular capture) or occurrence of high-degree AV-blocks mandating continuous pacing. Background: Ventricular pacing remains an essential part of contemporary transcatheter aortic valve implantation (TAVI). A temporary-right-ventricle (RV)-pacemaker lead is the standard approach for transient pacing during TAVI but requires central venous access. Methods: An observational registry including 672 patients who underwent TAVI between June 2018 and December 2020. Patients received pacing on the wire when necessary, unless there was a high-anticipated risk for conduction disturbances post-TAVI, based on the baseline-ECG. The follow-up period was 30 days. Results: A temporary-RV-pacemaker lead (RVP-cohort) was inserted in 45 patients, pacing on the wire (LVP-cohort) in 488 patients, and no pacing (NoP-cohort) in 139 patients. A bailout temporary pacemaker was implanted in 14 patients (10.1%) in the NoP-cohort and in 24 patients (4.9%) in the LVP-cohort. One patient in the LVP-cohort needed an RV-pacemaker for incomplete ventricular capture. Procedure time was significantly longer in the RVP-cohort (68 min [IQR 52–88.] vs. 55 min [IQR 44–72] in NoP-cohort and 55 min [IQR 43–71] in the LVP-cohort [p < 0.005]). Procedural high-degree AV-block occurred most often in the RVP-cohort (45% vs. 14% in the LVP and 16% in the NoP-cohort [p ≤ 0.001]). Need for new PPI occurred in 47% in the RVP-cohort, versus 20% in the NoP-cohort and 11% in the LVP-cohort (p ≤ 0.001). Conclusion: A restricted RV-pacemaker strategy is safe and shortens procedure time. The majority of TAVI-procedures do not require a temporary-RV-pacemaker.

Background The effect of myocardial injury (MI) post-transcatheter aortic valve implantation (TAVI) on clinical outcomes is controversial. This study aimed to evaluate the effect of MI severity on clinical outcome and left ventricle function 30 days post-TAVI and determine MI post-TAVI predictors. Methods Overall, 138 consecutive patients who underwent successful transfemoral TAVI using SAPIEN3 and diagnosed using echocardiography and computed tomography were analyzed. High-sensitivity cardiac troponin T (TnT) was evaluated at baseline, immediately, and at 24, 48, and 72 h post-TAVI. Echocardiography findings and N-terminal pro-B-type natriuretic peptide (Nt-pro BNP) levels were evaluated 30 days post-TAVI. Results Mean age and STS score were 84.4 ± 3.5 years and 6.4 ± 3.2%, respectively. All cases showed severe aortic valve stenosis. Peri-procedural MI was observed in 48 of 100 patients (48.0%). Patients were grouped into MI (n = 48) and non-MI (n = 52), without significant difference in characteristics. Pre-balloon aortic valvuloplasty rate and total pacing time were significantly higher in MI vs non-MI. Total rapid pacing time (TRPT) was an independent predictor for MI (OR 1.06; 95% CI 1.01–1.16; p = 0.04). Echocardiography and Nt-pro BNP changes 30 days post-TAVI were similar between groups. Conclusion Peri-procedural MI, assessed by TnT changes, was observed in 48% of patients. The MI was not associated with overt cardiac dysfunction, and the recovery of left ventricular function and Nt-pro BNP level occurred similarly by 30 day post-TAVI between both groups. In multivariate analysis, TRPT was associated with MI after SAPIEN3 implantation. Trial registration number UMIN000036669.

INTRODUCTION Catheter stability during atrial fibrillation ablation is associated with higher ablation success rates. Rapid cardiac pacing and high-frequency jet ventilation (HFJV) independently improve catheter stability. Simultaneous modulation of cardiac and respiratory motion has not been previously studied. The objective of this study was to determine the effect of simultaneous heart rate and respiratory rate modulation on catheter stability. METHODS Forty patients undergoing paroxysmal atrial fibrillation ablation received ablation lesions at 15 prespecified locations (12 left atria, 3 right atria). Patients were randomly assigned to undergo rapid atrial pacing for either the first or the second half of each lesion. Within each group, half of the patients received HFJV and the other half standard ventilation. Contact force and ablation data for all lesions were compared among the study groups. Standard deviation of contact force was the primary endpoint defined to examine contact force variability. RESULTS Lesions with no pacing and standard ventilation had the greatest contact force standard deviation (5.86 ± 3.08 g), compared to lesions with pacing and standard ventilation (5.45 ± 3.28 g; P

We report a case of revascularization of the right coronary artery via the epicardial collateral, for which we used transcoronary rapid pacing to obtain cardiac standstill while puncturing the distal chronic total occlusion (CTO) cap. To our knowledge, this is the first case in which this technique has been used in CTO. (Level of Difficulty: Advanced.), Graphical abstract, We report a case of revascularization of the right coronary artery via the epicardial collateral, for which we used transcoronary rapid pacing to…

Patients with myocardial infarction have an abundance of conduction channels (CC); however, only a small subset of these CCs sustain ventricular tachycardia (VT). Identifying these critical CCs (CCCs) in the clinic so that they can be targeted by ablation remains a significant challenge. The objective of this study is to use a personalized virtual-heart approach to conduct a three-dimensional (3D) assessment of CCCs sustaining VTs of different morphologies in these patients, to investigate their 3D structural features, and to determine the optimal ablation strategy for each VT. To achieve these goals, ventricular models were constructed from contrast enhanced magnetic resonance imagings of six postinfarction patients. Rapid pacing induced VTs in each model. CCCs that sustained different VT morphologies were identified. CCCs’ 3D structure and type and the resulting rotational electrical activity were examined. Ablation was performed at the optimal part of each CCC, aiming to terminate each VT with a minimal lesion size. Predicted ablation locations were compared to clinical. Analyzing the simulation results, we found that the observed VTs in each patient model were sustained by a limited number (2.7 ± 1.2) of CCCs. Further, we identified three types of CCCs sustaining VTs: I-type and T-type channels, with all channel branches bounded by scar, and functional reentry channels, which were fully or partially bounded by conduction block surfaces. The different types of CCCs accounted for 43.8, 18.8, and 37.4% of all CCCs, respectively. The mean narrowest width of CCCs or a branch of CCC was 9.7 ± 3.6 mm. Ablation of the narrowest part of each CCC was sufficient to terminate VT. Our results demonstrate that a personalized virtual-heart approach can determine the possible VT morphologies in each patient and identify the CCCs that sustain reentry. The approach can aid clinicians in identifying accurately the optimal VT ablation targets in postinfarction patients.

The transcatheter heart valve (THV) embolization is a rare but challenging complication in transcatheter aortic valve implantation (TAVI). We report the case of an 81-year-old man with Sapien 3 embolization caused by interrupted rapid pacing. In this setting, we describe the embolized THV management and the technique of the second Sapien 3 implantation.

Background and aims To compare the feasibility of Coronary Flow Velocity Reserve (CFVR) assessment in the left anterior descending (LAD) artery in four types of stress echocardiography (SE): dobutamine (DOB), dipyridamole (DIP), rapid pacing (PAC) and bicycle exercise (EXE). Methods and results We subjected 369 patients (mean age: 67±11 years) to SE with DOB (up to 40 mcg/kg/min, n=230), DIP (0.84 mg/kg, n=73), PAC (n=22) or EXE (n=44). CFVR was measured as the ratio of peak diastolic coronary flow velocity (CFV) during exercise, pharmacological stress or pacing and peak diastolic CFV at rest in distal or mid LAD. The feasibility was excellent during PAC (100%), DOB (95%) and DIP (95%) and lower during EXE (73%, p In multivariate analysis only the EXE protocol was a predictor of LAD flow loss during SE, with OR = 8.23 (95% CI 2.17 – 31.33), p=0.0019. CFVR was lower with PAC (1.8±0.4) as compared to DIP (2.2±0.6, p=0.0061) and DOB (2.2±0.6, p=0.0025), but similar to EXE (2.0±0.6, p=0.178), and correlated best with the peak heart rate in EXE and PAC, see Figure 2. Conclusion CFVR in LAD can be obtained during all forms of SE, but the feasibility is significantly higher with PAC and pharmacological tests as compared to EXE, which was identified in our study as the independent predictor of the loss of LAD flow recording at the peak of stress test. Moreover, CFVR values were the lowest in PAC group which however encompassed the older patients with more advanced coronary artery disease. Significant correlation between HR and CFVR observed in EXE and PAC suggests that in this type of SE cut-off value of CFVR should be probably indexed to maximal HR achieved. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

Cardiac alternans have crucial importance in the onset of ventricular fibrillation. The early explanation for alternans development was the voltage-driven mechanism, where the action potential (AP) restitution steepness was considered as crucial determining factor. Recent results suggest that restitution slope is an inadequate predictor for alternans development, but several studies still claim the role of membrane potential as underlying mechanism of alternans. These controversial data indicate that the relationship of restitution and alternans development is not completely understood. APs were measured by conventional microelectrode technique from canine right ventricular papillary muscles. Ionic currents combined with fluorescent measurements were recorded by patch-clamp technique. APs combined with fluorescent measurements were monitored by sharp microelectrodes. Rapid pacing evoked restitution-independent AP duration (APD) alternans. When non-alternating AP voltage command was used, Ca2+i-transient (CaT) alternans were not observed. When alternating rectangular voltage pulses were applied, CaT alternans were proportional to ICaL amplitude alternans. Selective ICaL inhibition did not influence the fast phase of APD restitution. In this study we found that ICaL has minor contribution in shaping the fast phase of restitution curve suggesting that ICaL—if it plays important role in the alternans mechanism—could be an additional factor that attenuates the reliability of APD restitution slope to predict alternans.

The assessment of coronary flow velocity reserve (CFVR) may improve the diagnostic and prognostic value of stress echocardiography (SE).The aim of the study was to compare the feasibility of CFVR assessment in the left anterior descending artery (LAD) in 4 modalities of SE: dobutamine, dipyridamole, rapid cardiac pacing, and exercise using cycle ergometer.We performed SE in 369 patients (mean [SD] age, 67 [11] years) with dobutamine (n = 230), dipyridamole (n = 73), rapid cardiac pacing (n = 22), or exercise (n = 44) between June 2017 and June 2020. We measured CFVR as the ratio of peak diastolic coronary flow velocity during exercise, pharmacological stress, or pacing to peak diastolic coronary flow velocity at rest in the distal or mid LAD.The feasibility of CFVR was excellent during rapid cardiac pacing (100%), dobutamine (95%), and dipyridamole (95%) and was lower during exercise (73%; P⁠0.01 vs other groups). In multivariable analysis, the exercise protocol was a predictor of the loss of blood flow in the LAD during SE (odds ratio, 7.89; 95% CI, 2.17–31.33; P = 0.002). The median (interquartile range) CFVR was lower with rapid cardiac pacing (1.7 [1.4–2.0]) as compared with dobutamine (2.1 [1.7–2.5]), dipyridamole (2.1 [1.8–2.5]), and exercise (2.0 [1.7–2.3]) (P⁠0.05 for all).CFVR in the LAD can be obtained during all forms of SE, but the feasibility is significantly higher with rapid cardiac pacing and pharmacological tests as compared with exercise, which was identified in our study as an independent predictor of the loss of blood flow during a blood flow recording in the LAD at the peak of stress test.

Objective : Electrotherapy remains the most effective direct therapy against lethal cardiac arrhythmias. When an arrhythmic event is sensed, either strong electric shocks or controlled rapid pacing is automatically applied directly to the heart via an implanted cardioverter defibrillator (ICDs). Despite their success, ICDs remain a highly non-optimal therapy: the strong shocks required for defibrillation cause significant extra-cardiac stimulation, resulting in pain and long-term tissue damage, and can also limit battery life. When used in anti-tachycardia pacing mode, ICDs are also often ineffective, as the pacing electrode can be far away from the centre of the arrhythmia, making it hard for the paced wave to interrupt and terminate it. Methods : In this paper, we present two conceptual intra-cardiac directional electrode configurations in silico based on novel arrangements of pairs of positive-negative electrodes. Both configurations have the potential to cause preferential excitation on specific regions of the heart. Results : We demonstrate how the properties of the induced field varies spatially around the electrodes and how it depends upon the specific arrangements of dipole electrode pairs. The results show that when tested within anatomically-realistic rabbit ventricular models, both electrode configurations produce strong virtual electrodes on the targeted endocardial surfaces, with weaker virtual electrodes produced elsewhere. Conclusions : The proposed electrode configurations may facilitate targeted far-field anti-tachycardia pacing and/or defibrillation, which may be useful in cases where conventional anti-tachycardia pacing fails. In addition, the conceptual electrode designs intrinsically confine the electric field to the immediate vicinity of the electrodes, and may, thus, minimize pain due to unnecessary extra-cardiac stimulation.

Multimodal picture integration has been developed for improvements of visualization of interventional procedure in congenital and structural heart disease. 3D rotational angiography (3DRA) was used for that purpose in the past, and a 3D dataset was than imposed as an overlay for fluoroscopy. But 3DRA includes a 180° turn of the X-ray arm in order to generate a 3D dataset, including additional contrast application of 4–5 s, rapid pacing, and preparation of the catheterization lab.

Cardiac alternans is a proarrhythmic state in which the action potential duration (APD) of cardiac myocytes alternate between long and short values and often occurs under conditions of rapid pacing of cardiac tissue. In the ventricles, alternans is especially dangerous due to the life-threatening risk of developing arrhythmias, such as ventricular fibrillation. Alternans can be formed in periodically paced tissue as a result of pacing itself. Recently, it has been demonstrated that this pacing-induced alternans can be prevented by performing constant diastolic interval (DI) pacing, in which DI is independent of APD. However, constant DI pacing is difficult to implement in experimental settings since it requires the real-time measurement of APD. A more practical way was proposed based on electrocardiograms (ECGs), which give an indirect measure of the global DI relaxation period through the TR interval assessment. Previously, we demonstrated that constant TR pacing prevented alternans formation in isolated Langendorff-perfused rabbit hearts. However, the efficacy of “local” constant DI pacing vs “global” constant TR pacing in preventing alternans formation has never been investigated. Thus, the purpose of this study was to implement an ECG-based constant TR pacing in a 1D numerical model of human ventricular tissue and to compare the dynamical behavior of cardiac tissue with that resulted from a constant DI pacing. The results showed that both constant TR and constant DI pacing prevented the onset of alternans until lower basic cycle length when compared to periodic pacing. For longer cable lengths, constant TR pacing was shown to exhibit greater control on alternans than constant DI pacing.

The use of US-guided vascular access and left ventricular rapid pacing could significantly reduce TAVR-related complications. This study suggests simple tricks to keep the procedure safer. Further multicenter studies are needed to confirm the present data.

Patients with scar-associated fibrotic tissue remodelling are at greater risk of ventricular arrhythmic events, but current methods to detect the presence of such remodelling require invasive procedures. We present here a potential method to detect the presence, location and dimensions of scar using pacing-dependent changes in the vectorcardiogram (VCG). Using a clinically-derived whole-torso computational model, simulations were conducted at both slow and rapid pacing for a variety of scar patterns within the myocardium, with various VCG-derived metrics being calculated, with changes in these metrics being assessed for their ability to discern the presence and size of scar. Our results indicate that differences in the dipole angle at the end of the QRS complex and differences in the QRS area and duration may be used to predict scar properties. Using machine learning techniques, we were also able to predict the location of the scar to high accuracy, using only these VCG-derived rate-dependent changes as input. Such a non-invasive predictive tool for the presence of scar represents a potentially useful clinical tool for identifying patients at arrhythmic risk., Graphical abstract, Highlights • Non-invasive assessment of scar arrhythmic risk remains a significant challenge. • Rate-dependent changes in vectorcardiograms convey the functional presence of scar. • Random forest machine-learning allows high accuracy for determining scar location.

Objectives This study aimed to investigate the safety and efficacy of ACURATE neo transcatheter aortic valve replacement (TAVR) facilitated by predilatation with the nonocclusive TrueFlow balloon catheter. Background Now that TAVR is moving forward, physicians have attempted to simplify and streamline the procedure and the so-called minimalist approach has become more popular. Methods We enrolled 142 patients (mean age: 82 ± 5 years, 61% female) in a prospective registry. Patients at low risk for intraprocedural third-degree atrioventricular block (AVB) underwent TAVR with the TrueFlow balloon without rapid pacing and without insertion of a provisional pacemaker (n = 121). The remaining 21 patients were predilated with rapid pacing using a provisional pacemaker and a standard balloon. Results Predilatation with the TrueFlow balloon was successful in all 121 patients. Postdilatation was less frequently required after predilatation with the TrueFlow (25% vs. 57%, p = .003). Moreover, median procedural duration with the TrueFlow was significantly shorter (42 [interquartile range, IQR: 34-53] vs. 55 [IQR: 46-61] min, p = .004). In-hospital outcomes were similar. At 30 days, there was no mortality, two (1%) patients had suffered a stroke and only four (3%) had required implantation of a new pacemaker. Conclusion Among patients with a low risk for intraprocedural third-degree AVB, the TrueFlow nonocclusive balloon catheter facilitates implantation of the ACURATE neo without the necessity of rapid pacing and a provisional pacemaker.

Left ventricular access for aortic valve intervention provides the opportunity to deliver rapid pacing over the guidewire for device positioning and deployment. Temporary pacing delivered via the left ventricle can obviate the need for venous access and has been shown to be a safe alternative to temporary right ventricular pacing. The technique requires some basic knowledge and experience in temporary cardiac pacing. We outline safe practical steps and common pitfalls in using this technique.

We thank Drs. Boukhris and Masson for their relevant letter regarding our multicenter randomized trial, EASY TAVI (Direct Left Ventricular Rapid Pacing via the Valve Delivery Guide-Wire in TAVI), comparing direct left ventricular and right ventricular stimulation in transcatheter aortic valve

This study investigated whether left ventricular (LV) stimulation via a guidewire-reduced procedure duration while maintaining efficacy and safety compared with standard right ventricular (RV) stimulation.Rapid ventricular pacing is necessary to ensure cardiac standstill during transcatheter aortic valve replacement (TAVR).This is a prospective, multicenter, single-blinded, superiority, randomized controlled trial. Patients undergoing transfemoral TAVR with a SAPIEN valve (Edwards Lifesciences, Irvine, California) were allocated to LV or RV stimulation. The primary endpoint was procedure duration. Secondary endpoints included efficacy, safety, and cost at 30 days.Between May 2017 and May 2018, 307 patients were randomized, but 4 were excluded because they did not receive the intended treatment: 303 patients were analyzed in the LV (n = 151) or RV (n = 152) stimulation groups. Mean procedure duration was significantly shorter in the LV stimulation group (48.4 ± 16.9 min vs. 55.6 ± 26.9 min; p = 0.0013), with a difference of -0.12 (95% confidence interval: -0.20 to -0.05) in the log-transformed procedure duration (p = 0.0012). Effective stimulation was similar in the LV and RV stimulation groups: 124 (84.9%) versus 128 (87.1%) (p = 0.60). Safety of stimulation was also similar in the LV and RV stimulation groups: procedural success occurred in 151 (100%) versus 151 (99.3%) patients (p = 0.99); 30-day MACE-TAVR (major adverse cardiovascular event-transcatheter aortic valve replacement) occurred in 21 (13.9%) versus 26 (17.1%) patients (p = 0.44); fluoroscopy time (min) was lower in the LV stimulation group (13.48 ± 5.98 vs. 14.60 ± 5.59; p = 0.02), as was cost (€18,807 ± 1,318 vs. €19,437 ± 2,318; p = 0.001).Compared with RV stimulation, LV stimulation during TAVR was associated with significantly reduced procedure duration, fluoroscopy time, and cost, with similar efficacy and safety. (Direct Left Ventricular Rapid Pacing Via the Valve Delivery Guide-wire in TAVR [EASY TAVI]; NCT02781896).

Directed differentiation methods allow acquisition of high-purity cardiomyocytes (CMs) differentiated from human induced pluripotent stem cells (hiPSCs); however, their immaturity characteristic limits their application for drug screening and regenerative therapy. The rapid electrical pacing of cardiomyocytes have been used for efficiently promoting the maturation of cardiomyocytes, here we describe a simple device in modified culture plate on which hiPSC-derived CMs (hiPSC-CMs) can form three-dimensional self-organized tissue rings (SOTRs). Using calcium imaging, we show that within the ring, traveling waves (TWs) of action potential spontaneously originated and ran robustly at a frequency up to 4 Hz. After 2 weeks, SOTRs with TW training showed matured features including structural organization, increased cardiac-specific gene expression, enhanced Ca2+-handling properties, an increased oxygen-consumption rate, and enhanced contractile force. We subsequently used a mathematical model to interpret the origination, propagation, and long-term behavior of the TWs within the SOTRs. This new idea for spontaneous hiPSC-CM maturation also has potential for pacing the electrical excitable cells such as neuron and retina cells for various applications.

Objective To evaluate the effect of Zhigancao decoction on reversal of right atrial myocardial fibrosis after rapid atrial pacing (RAP)-induced atrial fibrillation (AF). Methods New Zealand white rabbits were randomly divided into four groups: sham operation group (Group A: implanted electrodes, no RAP), pacing group (Group B: RAP-induced AF), Zhigancao soup water decoction Yin group (Group C: RAP-induced AF followed by Zhigancao soup Yin prescription twice a day for 30 days), and Zhigancao soup group (Group D: RAP-induced AF followed by Zhigancao water decoction twice a day for 30 days). The atrial myocardium was then examined for myocardial fibrosis by Masson staining, and protein expression of matrix metalloproteinase-9 (MMP-9) was immunohistochemically assessed. The right atrial appendage tissue field action potential duration (fAPD) was measured by microelectrode arrays. Results RAP successfully induced AF. Myocardial fibrosis was more severe in Groups B and C and less severe in Group D. Protein expression of MMP-9 was strongly positive in Groups B and C and weakly positive in Group D. The fAPD was significantly decreased in Groups B and C, but the decrease in Group D was not significant. Conclusion Zhigancao decoction can reverse AF-induced myocardial fibrosis in rabbits and shorten the fAPD.

Objectives We sought to demonstrate the safety and efficacy of rapid left ventricular (LV) pacing through the guidewire during balloon aortic valvuloplasty (BAV) and Transaortic valve implantation (TAVI). Background Right ventricular temporary pacing during TAVI and BAV is time-consuming and associated with vascular and pericardial complications. Methods Rapid left ventricular pacing was provided via the back-up 0.035″ guidewire. The cathode of an external pacemaker was placed on the tip of the 0.035″ wire and the anode on a needle inserted into the groin. Insulation was ensured by the balloon or TAVI catheter. Results 38 BAV and 87 TAVI procedures were performed in 113 consecutive patients in three centers with one for one pacing (160–200 bpm) in all patients. A significant reduction in blood pressure was achieved with a mean systolic pressure of 44 mm Hg during stimulation. Mean procedural time was 49.7 ± 31 min for BAV and 68.7 ± 30.9 for TAVI. A temporary venous pacemaker was required in 12 patients; only 12% of TAVI patients had a femoral central venous catheter. Femoral venous puncture was not performed in BAV patients. No venous vascular complications were observed. One case of successfully treated tamponade (0.8%) occurred 8 hr post procedure. In-hospital mortality rates were 4.6% and 2.6% in the TAVI and BAV groups, respectively. Conclusions Use of the LV guidewire for rapid pacing during BAV and TAVI was shown to be simple, reproducible, and prevented complications associated with RV temporary leads thus potentially simplifying TAVI and enhancing its safety. © 2016 Wiley Periodicals, Inc.

Similar to endless loop tachycardia (ELT), repetitive nonreentrant ventriculoatrial synchrony (RNRVAS) is a ventriculoatrial (VA) synchrony pacemaker-mediated arrhythmia. RNRVAS was first described in 1990 and can only occur in the presence of retrograde VA conduction and dual-chamber or cardiac resynchronization devices with tracking (P-synchronous ventricular pacing such as DDD, DDDR) or nontracking pacing modes that allow AV-sequential pacing (DDI, DDIR). RNRVAS is promoted by (1) high lower rate limit or any feature that allows rapid pacing, (2) long AV intervals, or (3) long postventricular atrial refractory period (PVARP). In contrast to ELT, RNRVAS is a less well-recognized form of pacemaker-mediated arrhythmia; thus, unlike ELT, there are no specific device algorithms to prevent, recognize, and terminate RNRVAS. However, RNRVAS has been recently shown to occur frequently. We present a series of cases, some of which were found fortuitously. Owing to its clinical implications, we propose that algorithms should be developed to prevent, identify, and terminate RNRVAS.

Exercise-induced left bundle branch block is rare and can be demonstrated with exercise testing. When the heart rate reaches a certain threshold, the QRS widens into left bundle branch block. This paper describes a patient with exercise-induced left bundle branch block related angina and dyspnea, who responded to cardiac resynchronization therapy. We documented the potential benefits of cardiac resynchronization therapy with a left ventricular rapid pacing study prior to its implantation. Although exercise-induced left bundle branch block is not a current indication for cardiac resynchronization therapy in patients such as ours, it could be considered when conventional drug therapy fails.

Transcatheter implantation of balloon expandable valves in high-risk patients with degenerated tricuspid bioprostheses has been reported since 2010 [1, 2]. Although there have been cases where the SAPIEN valve was implanted in the tricuspid position without rapid pacing [3, 4], invasive rapid ventricular pacing is usually applied during valve deployment. We present a case report documenting for the first time the use of noninvasive, external rapid pacing delivered through defibrillation sticker-pads during transfemoral implantation of the Edwards SAPIEN XT valve for tricuspid valve bioprosthesis stenosis.

The effects of continuous vagal nerve stimulation (VNS) on atrial neural remodeling during atrial fibrillation (AF) remain unclear.To test the hypothesis that VNS affects atrial neural remodeling and reduces AF inducibility.Twenty rabbits were randomly divided into two groups: rapid atrial pacing (RAP) group and RAP with VNS group. AF inducibility studies and atrial histologic analyses were performed after 4 weeks.Five rabbits of RAP group (5/10) in the RAP group developed sustained AF. None of rabbits in RAP with VNS group had developed AF. The incidence of sustained AF in VNS group was significant lower than that in rapid pacing group (P.01). Treatment with VNS resulted in a significant reduction in atrial neural remodeling and AF duration (P.01).Atrial neural remodeling plays an important role in the initiation and maintenance of AF. Modulating autonomic nerve function with VNS can contribute to AF control.

Background We sought to determine whether right ventricular stunning could be detected after supply (during coronary balloon occlusion [ BO ]) and supply/demand ischemia (induced by rapid pacing [ RP ] during transcatheter aortic valve replacement) in humans. Methods and Results Ten subjects with single‐vessel right coronary artery disease undergoing percutaneous coronary intervention with normal ventricular function were studied in the BO group. Ten subjects undergoing transfemoral transcatheter aortic valve replacement were studied in the RP group. In both, a conductance catheter was placed into the right ventricle, and pressure volume loops were recorded at baseline and for intervals over 15 minutes after a low‐pressure BO for 1 minute or a cumulative duration of RP for up to 1 minute. Ischemia‐induced diastolic dysfunction was seen 1 minute after RP (end‐diastolic pressure [mm Hg]: 8.1±4.2 versus 12.1±4.1, P BO (end‐diastolic pressure [mm Hg]: 8.1 ± 4.0 versus 8.7±4.0, P =0.03). Impairment of systolic and diastolic function after BO remained at 15‐minutes recovery (ejection fraction [%]: 55.7±9.0 versus 47.8±6.3, P P RP group at 15‐minutes recovery (end‐diastolic pressure [mm Hg]: 8.1±4.1 versus 9.9±4.4, P =0.03) and there was also sustained impairment of load‐independent indices of systolic function at 15 minutes after RP (end‐systolic elastance and ventriculo‐arterial coupling [mm Hg/mL]: 1.25±0.31 versus 0.85±0.43, P Conclusions RP and right coronary artery balloon occlusion both cause ischemic right ventricular dysfunction with stunning observed later during the procedure. This may have intraoperative implications in patients without right ventricular functional reserve.

Cardiac alternans may lead to life-threatening arrhythmias or sudden cardiac death. Thus, finding an effective method to suppress alternans is crucial. In this paper, we demonstrate that the time needed to control cardiac alternans induced by rapid pacing using the T+T-feedback control can be dramatically shortened if the extracellular calcium concentration is lowered by a very small amount when the control is turned on. Numerical simulations are performed on the Hund-Rudy dynamic (HRd) model for single cell. Since controlling alternans is important as it can be a precursor of sudden cardiac death, the results of our research may have important clinical implications and will lead to the development of a better control scheme for alternans or a smart defibrillator.

The Purkinje system (PS) and the His bundle have been recently implicated as an important driver of the rapid activation rate after 1-2 minutes of ventricular fibrillation (VF). It is unknown whether activations during VF propagate through the His-Purkinje system to other portions of the the working myocardium (WM). Little is known about restitution characteristic differences between the His bundle and working myocardium at short cycle lengths. In this study, rabbit hearts (n = 9) were isolated, Langendorff-perfused, and electromechanically uncoupled with blebbistatin (10 μM). Pacing pulses were delivered directly to the His bundle. By using standard glass microelectrodes, action potentials duration (APD) from the His bundle and WM were obtained simultaneously over a wide range of stimulation cycle lengths (CL). The global F-test indicated that the two restitution curves of the His bundle and the WM are statistically significantly different (P

The aim of the present study was to investigate whether transfemoral implantation of the Acurate neo transcatheter heart valve without pre-dilation is feasible.Between December 2014 and December 2016, 294 patients were treated with the Acurate neo prosthesis at our center. Of these, 72 cases were performed without pre-dilation. The decision to omit pre-dilation was at the discretion of the operator, preferably in the case of mild to moderate aortic valve calcification (AVC). Propensity matching (1:1) resulted in 48 cases in each group. Main outcomes of interest were device success according to VARC-2 criteria, residual aortic regurgitation (AR) ≥ 2°, and rate of post-dilation.Median [IQR] age in patients without pre-dilation was 82.7 years [78.6–85.6], STS score was 4.6% [3.4–6.1], and AVC-score was 1436 AU [1043–1682] with mild and moderate AVC in 63.9% and 36.1% of cases, respectively. Device success was achieved in 94.4% of cases, post-dilation was necessary in 26.4%, and one (1.4%) patient had moderate AR. In the matched population, there were no differences regarding device success, rate of AR ≥ 2°, need for post-dilation, and post-procedural mean gradient, but the group without pre-dilation had shorter procedure (34.0 min [27.0–38.8] vs. 43.0 min [34.3–52.0]; p0.001) and fluoroscopy times (7.4 min [5.7–9.0] vs. 9.9 min [7.9–13.5]; p0.001).In select patients with mild to moderate AVC, transfemoral implantation of the Acurate neo without pre-dilation is feasible and safe. This allows for a straightforward procedure that may be performed without rapid pacing in the majority of cases.

Electrophysiological heterogeneity in action potential recordings from healthy intact hearts remains highly variable and, where present, is almost entirely abolished at fast pacing rates. Consequently, the functional importance of intrinsic action potential duration (APD) heterogeneity in healthy ventricles, and particularly its role during rapidly activating reentrant arrhythmias, remain poorly understood. By incorporating both transmural and apicobasal APD heterogeneity within a biventricular rabbit computational model and comparing with an equivalent homogeneous model, we directly investigated the functional importance of intrinsic APD heterogeneity under fast pacing and arrhythmogenic protocols. Although differences in APD were significantly modulated at the tissue level during pacing and further reduced as pacing frequency increased, small differences were still noticeable. Such differences were further marginally accentuated/attenuated via electrotonic effects relative to wavefront propagation directions. The remaining small levels of APD heterogeneity under the fastest pacing frequencies resulted in arrhythmia initiation via heterogeneous conduction block, in contrast to complete block in the homogeneous model. Such induction mechanisms were more evident during premature stimuli at slower paced rhythms where intrinsic heterogeneity remained to a greater degree. During sustained arrhythmias, however, intrinsic heterogeneity made little difference to overall reentrant behavior, either visually, or in terms of duration, metrics quantifying filament/phase singularity dynamics, and global electrocardiogram characteristics. These findings suggest that, despite being important during arrhythmia initiation, intrinsic electrophysiological heterogeneity plays little functional role during rapid pacing and sustained arrhythmia dynamics in the healthy ventricle and thus questions the need to incorporate such detail in computational models when simulating rapid arrhythmias.

ObjectivesThis study sought to evaluate the exact location of Edwards SAPIEN (Edwards Lifesciences, Irvine, California) devices in different stages of implantation and to quantify possible operator-independent device movement during final deployment.BackgroundAccurate device positioning during transcatheter aortic valve implantation is crucial in order to achieve optimal results.MethodsThis multicenter study consisted of 68 procedures with reliable pacemaker capture. Device positions were assessed using fluoroscopic images and the C-THV system (Paieon Medical, Rosh Ha'Ayin, Israel).ResultsThe location after implantation was significantly higher than in the final stage of rapid pacing: 16.7 ± 16.3% of device height below the plane of the lower sinus border versus 32.6 ± 13.8%, p < 0.0001. Operator-independent device-center upper movement during final deployment was 2 ± 1.43 mm, range: −1.3 to 4.6 mm. Device movement was asymmetrical, occurring more in the lower part of the device than in its upper part (3.2 ± 1.4 mm vs. 0.75 ± 1.5 mm, p < 0.001), resulting in device shortening. Multivariate analysis revealed that moderate and severe aortic valve calcification had 49% higher upward movement than mild calcification (p = 0.03), and aortic sinus volume was negatively correlated with movement size (r = −0.35, p = 0.005). This movement was independent of device version (SAPIEN vs. SAPIEN XT), procedural access (transfemoral vs. transapical), and interventricular septum width.ConclusionsThe final Edwards SAPIEN position is mostly aortic in relation to the lower sinus border. There is an operator-independent upward movement of the device center during the final stage of implantation. Anticipated upward movement of the device should influence its positioning before final deployment.

Aims Remodelling of the extracellular matrix (ECM) plays an important role in the production of arrhythmogenic substrate for atrial fibrillation (AF), and is considered to be promoted by the connective tissue growth factor (CTGF). Our objective was to assess the relationship between CTGF and ECM synthesis, and the effect of olmesartan on these processes. Methods and results Fifteen canine AF models were produced by rapid atrial stimulation. They were divided into three groups: pacing control ( n = 5): 6-week pacing, pacing + olmesartan ( n = 5): pacing with olmesartan (2 mg/kg/day), and non-pacing group ( n = 5). In the pacing control group, messenger ribonucleic acid expressions of CTGF and collagen types 1 and 3 were up-regulated in comparison with the non-pacing group ( P < 0.05) while transforming growth factor-β (TGF-β) did not exhibit a significant difference. In the pacing + olmesartan group, these up-regulations were suppressed ( P < 0.05). In fluorescent immunostaining, the expression of CTGF was localized in the cytoplasm. The protein level of collagen type 3 was increased in the pacing control and it was suppressed in the pacing + olmesartan group. Conclusions CTGF and associated genes were up-regulated in the atria with the appearance of fibrosis. Because this up-regulation was independent of TGF-β and suppressed by olmesartan, CTGF up-regulation was considered to be mediated by angiotensin II.

Our objective was to investigate the influence of patient heart geometry and location of fibrofatty diseased tissue in arrhythmogenic cardiomyopathy on conduction properties in an organ-level model of human electrophysiology. Models including fibrofatty regions were generated from different manifestations of disease progression (via electroanatomic mapping). Non-viable tissue was represented by a passive membrane, and the disturbance in intercellular junctions associated with arrhythmogenic cardiomyopathy by decreased conductivities. At rapid pacing, a shorter action potential in arrhythmogenic cardiomyopathy results in propagation depending on fibrofatty pattern and activation sites, while activation is blocked in the control case. In the model, global conduction velocity through tissue with fibrofatty infiltration is faster than for control during rapid pacing. Increasing differences in conduction velocity between fibrofatty patterns start to develop at rapid pacing prior to early activation associated with fibrofatty infiltration.

To report on 2 rare cases of balloon-expandable transfemoral transcatheter aortic valve implantation, where a trapped balloon led to complications requiring acute intervention. Both patients were elderly with increased risk profile and had been discussed by the heart team. After standard positioning of the valves using a transfemoral approach, retrieval of the pusher before deployment of the valve was missed. In 1 patient, rapid pacing was continued, the balloon deflated, the pusher pulled back and the balloon repositioned and reinflated. In the other patient, valve migration into the left ventricle occurred. A second valve was deployed. The embolized valve was then recovered from the ventricle via transapical access. Complications can occur in transcatheter aortic valve implantation, even when they are very rare. A predeployment check list, indicating key procedural steps on a standardized basis, should always be followed to easily prevent mishaps.

Cardiac tamponade is one of the important life-threatening complications during transcatheter aortic valve implantation (TAVI). This complication is often due to right ventricular (RV) perforation by the temporary pacing lead. This study sought to assess the safety and efficacy of rapid pacing with

Transcatheter aortic valve replacement (TAVR) is an established therapy for patients with aortic stenosis [(1)][1]. Rapid pacing (RP), to ablate left ventricular (LV) ejection, stabilizes deployment and is necessary for balloon-expandable TAVR although it is less important for repositionable, self

Aims The first seconds of ventricular fibrillation (VF) are well organized and can consist of just one to two rotating waves (rotors). New rotors are spawned when local propagation block causes wave fragmentation. We hypothesized that this process, which leads to fully developed VF, begins at a consistent anatomic site. Methods and results We initiated VF with a stimulus timed to the local T-wave in 10 isolated pig hearts. Hearts were stained with a voltage-sensitive dye and four video cameras recorded electrical propagation panoramically across the epicardium. In each VF episode, we identified the position of the first wavebreak event that produced new rotor(s) that persisted for at least one cycle. The first such wavebreak occurred along the anterior right ventricular insertion (ARVI) in 26 of 32 VF episodes. In these episodes, wavebreak sites were 6 ± 4 mm from the midline of the ARVI. In the remaining 6 episodes, wavebreak sites were 24 ± 5 mm from the midline on either the LV or RV. During rapid pacing, conduction speed was locally depressed at the ARVI when waves crossed parallel to the midline. Action potential duration (APD) was slightly longer (2.2 ± 2.1 ms) at the ARVI compared with other sites ( P < 0.01). Temporal APD alternans were small and not unique to the break site, suggesting that dynamic APD properties were not the cause of wavebreak. Conclusion The ARVI is the dominant site for wavebreak at the onset of VF in normal myocardium. This may be due to the anatomic complexity of the region.

A 65-year-old recipient of an implantable cardioverter defibrillator suffering from ventricular noncompaction developed storms of ventricular tachycardia (VT). Epicardial voltage mapping revealed the presence of a large low-voltage area in the left ventricular apical and inferoposterior wall, and isolated delayed potential was recorded over 1.5 cm in the posterior border between low and normal myocardial voltage. Pacemapping at the delayed potential recording site produced two different QRS depending on pacing output strength, and these two QRS morphologies were similar to clinically documented VTs. During one of the VTs, a mid-diastolic potential was recorded from the site with the delayed potential, and rapid pacing produced concealed entrainment. After epicardial radiofrequency ablation of the isolated delayed potential, VTs were noninducible and the VT storm was suppressed.

A 61-year-old woman, 6 months after orthotopic heart transplantation (OHT), presented with gradual-onset class III dyspnea and fatigue for 4 months. Her transplantation procedure was significant for right ventricular sternal adhesions after left ventricular assist device placement and significant

The atrial potential duration (APD) restitution has been suggested to play an important role in ventricular fibrillation; however, its role in atrial fibrillation (AF) has not been determined. This study sought to investigate the APD restitution properties in two different AF models: vagally mediated AF and 6-h rapid atrial pacing-induced AF.Twenty anaesthetized open-chest dogs were assigned to Group I, vagally mediated AF (n= 8) or Group II, 6-h rapid atrial pacing-induced AF (n= 12). In both groups, the monophasic APD was subsequently recorded at multiple pulmonary vein and atrial sites. The APD restitution curve was constructed using a dynamic pacing protocol and determined by plotting each APD(90) against the preceding diastolic interval at incremental atrial pacing rates at eight sites. In Group I, vagal stimulation significantly shortened the APD(90), flattened the APD restitution curve (slopes1), and suppressed the APD alternans at each site, while increasing the AF inducibility and duration (P0.05 for all). In Group II, 6-h rapid pacing-induced APD shortening steepened the restitution curves (slopes1), facilitated the APD alternans, and also increased the incidence and duration of AF (P0.05 for all). The spatial dispersion of APD restitution was significantly increased in both groups.This study showed distinct atrial APD restitution properties in vagally mediated AF and 6-h rapid pacing-induced AF, indicating specific restitution kinetics in different mechanisms of AF.