High Pacing Research Articles

Beneficial effects of high output His bundle pacing in patients with heart failure, narrow QRS

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac Resynchronization Therapy (CRT) decreases heart failure (HF) hospitalizations and mortality and increases left ventricular Ejection Fraction (EF) in patients with dilated cardiomyopathy, left bundle branch block and QRS>130msec1. However, CRT is not beneficial in HF patients with narrow QRS3. Purpose We performed His Bundle Pacing (HBP) with high output (3.5V/1msec) in HF patients with dilated or ischemic cardiomyopathy and narrow QRS to prove hemodynamic benefit independently of the QRS duration or AV delay shortening. Methods 9 male patients with dilated cardiomyopathy (EF<35%) and narrow QRS (<110ms) were referred for implantation of a defibrillator. We implanted an ICD- HBP system, and we collected clinical, echocardiographic, and electrocardiographic data. Results We obtained HBP in all 9 patients successfully. Basal mean EF was 31±4% and increased to 43±6% (P<0.001) after a median follow-up of 116 days. Left ventricular end-diastolic diameter and left ventricular end-diastolic volume decreased from 62±5 to 59±6ml (P=0.014) and from 188±87 to 144±35ml (P=0.095), respectively. Left ventricular end-systolic volume decreased from 139±78 to 85±29 (P=0.035). NYHA class decreased by one class in every patient after only one month. Baseline QRS duration remained stable after pacing from 107±7 to 118±15ms. In one patient an iatrogenic right bundle branch block was created which was corrected partially by His bundle pacing. PQ after implantation was shorter (from 167±23 to 121±14 (P=0.030) so as to pace the ventricle. HBP threshold was 1.24V±0.50/1msec, the impedance was 529±116 Ohms while R-wave was 3.8±1.7mV. In one out of 9 patients, threshold increased from 1 to 2V/1msec in 6months and then remained stable. In the other eight patients, threshold remained stable. Conclusions HBP in HF patients with dilated cardiomyopathy and narrow QRS improves hemodynamic function and decreases NYHA class. This benefit appears to be produced by a higher stimulation output. We cannot exclude that a very short AV delay could be favorable. To our knowledge these are the first cases of beneficial HBP in HF patients with narrow QRS. There is urgent need for large, randomized clinical trials.

Leadless pacing in the elderly: exit strategy or valid alternative?

Abstract Funding Acknowledgements Type of funding sources: None. Background The need for cardiac pacing progressively increases with age and the elderly constitute a special subset of patients, being often very fragile and at a greater risk for procedural complications. Leadless pacing systems appear to be a safe and effective option, being devoid of most complications associated with traditional transvenous pacing systems. Purpose This study aimed to analyze a single-center experience with M-TPS (Micra Transcatheter Pacing System) implantation in terms of safety and efficacy in a long-term follow-up. Methods Between May 2014 and November 2022, 193 patients underwent M-TPS implantation in our Center, all patients fulfilled standard criteria for pacemaker implantation with indication to receive either VVI or VDD pacing. We divided the study population into two groups according to age (group 1 < 79 y vs group 2 >= 80 y) and analyzed procedural outcomes, electrical performance of the system at follow-up (FU), rate of procedural major complications and of device-related events at FU. Results In 95/193 cases (69 males, 73%) M-TPS was implanted in patients > 80 y. There were no statistically significant differences between groups in baseline characteristics. Implant procedure was successful in all cases and no device-related events were registered during FU. Patients were followed-up for an average of 18 months, up to 7 years. No differences were observed between groups in procedure duration, single device delivery (group 1 vs group 2: 62.1 vs 69.6%, p=0.17), fluoroscopy time [10 (IQR 6-14) vs 8.5 (IQR 6-12.5) minutes, p=0.27], electrical performance at implant: pacing threshold [0.44 (0.38-0.63) vs 0.5 (0.38-0.75) V/0.24 ms, p=0.39]; impedance [710 (610-840) vs 700 (600-810) Ohm, p=0.56]; R wave amplitude [9.3 (6 -13.5) vs 8.2 (6 -11.9) mV, p=0.68] and at 6 months follow-up : pacing threshold [0.5 (0.38-0.5) vs 0.38 (0.38-0.5) V/0.24 ms, p=0.25]; impedance [580 (500-640) vs 570 (530-680) Ohm, p=0.38]; R wave amplitude [13.2 (9.5-17) vs 9.7 (7.8-16.7) mV, p=0.17]. The only statistically significant difference was found in the percentage of ventricular pacing (Vp%), which was higher in group 2 [5.3 (IQR 0.5-35) vs 38% (IQR 14-83), p=0.001] and stayed higher at a 12 months follow-up [11 (1-53) vs 60% (10-94)], p=0.001). High pacing threshold (>= 1mV@0.24ms) at implant was present in thirty-one patients (14 vs 19%, p=0.43). Conclusions As the population ages the incidence of rhythm disturbances raises, increasing the need for cardiac pacing. It is imperative to find a therapeutic solution that suits the elderly offering them high efficacy and a low rate of complications. MTP-S implant is an effective and safe procedure in elderly patients with similar electrical performance and outcomes compared with younger patients at long-term follow-up. While initially thought for patients that could not undergo traditional pacing interventions, MTP-S is now emerging as a valid substitute.

Acute success, stability and safety of left bundle branch area pacing with steerable catheter and stylet-driven leads: A single center experience

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Right ventricular apical pacing is associated with adverse outcomes and there is an increasing preference to perform conduction system pacing as it allows for more physiological left ventricular activation. His-bundle pacing is known to be technically challenging and results in higher pacing thresholds and increased rates of lead dislodgement. Left bundle branch area pacing (LBBAP) is an emerging alternative form of conduction system pacing. Purpose We aim to study the acute success rates, short-term stability and safety using steerable catheter and stylet-driven (SD) leads for the purpose of LBBAP. Methods 40 consecutive patients who underwent LBBAP with steerable catheter and SD leads in our center from August 2021 to November 2022 were included in this series. Patients’ demographics, pacing indications, baseline QRS morphologies and duration and left ventricular ejection fraction (LVEF) were analysed. Acute success was defined as achieving stimulation to LV activation time (Stim-LVAT) ≤75ms or incomplete right bundle branch paced morphology in V1 [1, 2]. We also reported any left bundle branch (LBB) potential (if present) and the V6-V1 interpeak interval. All lead parameters and complications in the immediate (1 day) and short-term (1 week and 3-6 months) timeframe were evaluated. Results 40 patients' age (mean 72.75), gender (male 52.5%), body mass index (mean 24.15) and LVEF (mean 52.75%) were analysed. Pacing indications included sinus nodal dysfunction (25%), atrioventricular block (70%), heart failure with failed cardiac resynchronisation therapy (CRT) (2.5%) and atrial fibrillation (AF) requiring atrioventricular node ablation (2.5%). We achieved an acute success rate of 87.5% (5% with left ventricular septal pacing, 5% converted to conventional right ventricular septal pacing, and 2.5% converted to CRT). Reasons for failure to achieve successful LBBAP include persistent left superior vena cava, high pacing thresholds or inability to burrow lead into the septum for acceptable V1 morphology and Stim-LVAT due to resistance encountered during turning of the lead. 51.43% patients of the successful LBBAP patients had LBB potential present and/or interpeak interval >33ms [3]. Immediate and short-term lead parameters were stable and acceptable in all cases. There were no complications (such as lead dislodgement, rise in lead impedance or threshold) reported during the acute and short-term follow-up. Conclusion LBBAP is successful in 87.5% of our cases with use of steerable catheter deploying stylet-driven leads and is proven to be a safe and feasible method for conduction system pacing. Incremental experience with the delivery tools will further improve successful implantation. Longer term follow-up of these patients is needed to determine the long-term safety and stability of LBBAP using steerable catheter and stylet-driven leads.

Expert opinion on optimal programming strategy to increase AV synchrony in different profiles of patients implanted with leadless ventricular pacemaker

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Medtronic Background Recently published real-world data showed that Micra leadless pacemaker implanted in the right ventricle can provide atrioventricular (AV) synchronous pacing by accelerometer-based mechanically sensing atrial contractions in patients with a high pacing burden (1). Routinely performed programming optimization of several novel parameters (particularly concerning the A3 and A4 windows) is key to improving AV synchrony (AVS). Purpose This project aims to define optimal programming recommendations for defined patient profiles. Methods An Experts Panel (ExpP), made up of 11 electrophysiologists from high-volume centers (37±17 Micra AV procedures/year) contributing to the Medtronic Micra AV prospective Post Approval Registry (PAR), was assembled to share their opinion about the optimal programming strategy to improve AVS in patients with: 1) slow sinus rhythm and high degree AV block, 2) fast sinus rhythm and high degree AV block, 3) intermittent AV-block. The following steps were followed: - Data from Micra AV PAR database were retrospectively analyzed and shared with ExpP. - An online survey was completed by the ExpP to evaluate their current programming strategy, based on PAR data. - After a face-to-face meeting to discuss the survey results, a second survey round was completed to reach consensus on the optimal programming strategy. Agreement was considered reached when >75% of responders did not disagree. Results Specific detailed programming recommendations have been developed for the three different patient profiles (Figure 1). Most importantly, it was agreed that Auto A3 Threshold and tracking check should be turned off in all patients, AV conduction mode switch should be turned off in all patients with high degree AVB, and the lower rate should be programmed in general to 50bpm. In addition, the following general recommendations were agreed on by the ExpP: - A pre-implant echocardiogram with a particular focus on diastolic function should always be performed to identify patients who may benefit from Micra AV implantation. - Micra AV auto-setup should always be performed at implant. - Before discharge, basic adjustments based on results of the Manual Atrial. Mechanical (MAM) test, patient activity level, and age should be performed. - At each follow-up visit, fine-tuning programming based on patient feedback, device data (in particular %AM-VP) and performance of a MAM Test. Conclusions An ExpP of Micra AV implanters agreed on general recommendations for Micra AV patients’ management before implant and during follow-up. Specific programming recommendations for patients with slow sinus rhythm and high degree AV block, fast sinus rhythm and high degree AV block, and intermittent AV block have been developed. A validation phase will show if the application of these indications in clinical practice may improve AVS.

Research on knowledge representation and modeling of health management based on fuzzy ontology

The long-term maintenance of good condition for equipment is the basis of carrying out combat missions under the high technology and fast pace of modern war. However, the knowledge in the health management field at present has the characteristics of distribution, multi-source, heterogeneity and uncertainty, which seriously affects the efficiency of knowledge sharing and reuse. In order to improve the utilization of health management knowledge, an ontology-based knowledge representation method is proposed to describe knowledge in a unified and standardized way, and the classical ontology is extended to express the uncertain knowledge in the field of health management. In addition, to improve the maintenance and knowledge updating efficiency, a global ontology model and a hierarchy, time and activity (HTA) ontology model are constructed. This paper takes the guidance subsystem of a missile as an example to illustrate the process of knowledge modeling. The results show this method realizes knowledge sharing in the health management field and can provide decision support for health management of equipment.

Electrophysiological characterization of a 19-years-old male marathon runner suffering a sudden cardiac death

1 in 50,000 of athletes suffers a cardiac student death (SCD) per year, more of them under 35 years of age. Around 25% of these patients had normal structure, implying that other electrical disorder cause these SCD. Determine the electrophysiological causes of a SCD of a young 19-years-old occurred during a marathon with any heart structural diseases. Pathologic left ventricle (PLV) (n = 1, male, 19-years-old) and control left ventricle (CLV) (n = 1, female, 56-years-old) were perfused and imaged using high resolution optical mapping and Di-4-ANEPPS like a dye. Endocardial and endocardial free wall and his bundle were paced to obtain activation time (AT), repolarization time (RT) and action-potential duration (APD). Purkinje-muscle junctions (PMJs) were determine like activation origins far from the his bundle pacing. Effective refractory period (ERP) was determined using S1S2S3S4 short-coupled pacing. The protocol was repeated after isoplenalie injection [500 nM] like β-adrenergic receptor agonist. His-ventricle activation at high frequency pacing was higher in PLV (143ms) than in control (84ms) and decrease in both at similar levels under ISO (≈60ms). APD gradient increase was observed in PLV near PMJs under ISO (from 3ms/mm to 40ms/mm) and any gradient was observed in the control one. Ectopic episodes were observed in PLV under ISO and 82% of the origins had less that 4 mm of distance with the PMJs. In PLV, the ERP in His-pacing is always lower (320, 260, 250 ms) than endocardial (350, 315, 285 ms) pacing but in CLV, the His-pacing ERP was always higher (320, 260, 240 ms) that endocardial pacing (280, 240, 220 ms). Ventricular fibrillation (VF) was observed in PLV after his bundle pacing at high frequency (more than 330 ms) and any VF was observed in CLV. During this VF, 76% of the focal activities had less than 4 mm of distance with the PMJs. Conduction system (CS) of the PLV shows high sensitivity to high frequency pacing and to presence of ISO. Ectopic episodes and APD gradient near PMJs may show the role of Purkinje network like arrhythmic source. Indeed, the shorter ERP during His-pacing than in the endocardium, give the possibility to produce a macro-re-entry in the conduction system and maintain the arrhythmia with focal activities. CS abnormalities likely played a critical role in arrhythmogenicity and maintenance of VF in this patient during sudden cardiac death.

PO-05-002 ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY WITH EXTENSIVE ABNORMAL SUBSTRATE: IS ISOLATION POSSIBLE?

In arrhythmogenic right ventricular cardiomyopathy (ARVC) patients with extensive right ventricular free wall (RVFW) abnormal substrate, large area homogenization with combined epicardial and endocardial approach is time consuming and often inadequate for modification. We aim to explore the feasibility and efficacy of RVFW abnormal substrate isolation in such patients to control ventricular tachycardia (VT). Eight consecutive ARVC patients with VT who had extensive abnormal RVFW substrate were included. VT induction was performed before substrate mapping and modification. Detailed voltage mapping was done during sinus rhythm. A circumferential linear lesion was deployed along the border zone of low-voltage-area on the RVFW to achieve electrical isolation. Other small areas with fractionated or late potentials were further homogenized. All eight patients had extensive RV endocardial low-voltage-area (113.8 ± 84.1 cm2, 49.6 ± 29.8%) and dense scar (59.6 ± 39.8 cm2, 25.0 ± 14.1%). Electrical isolation of abnormal substrate was achieved in 5/8 (62.5%) patients via endocardial approach alone and 3/8 (37.5%) patients via a combination of endocardial and epicardial approach. Electrical isolation was verified by slow automaticity (5/8, 62.5%) or RV non-capture (3/8, 37.5%) during high output pacing inside the encircled area. VTs were induced in 6 patients before ablation and all patients rendered non-inducible after ablation. During a median follow-up of 43 months (range 24-53), 7/8 (87. 5%) patients remained free of sustained VT. Electrical isolation of RVFW is feasible and effective in ARVC patients with extensive abnormal substrate and is associated with excellent long-term rhythm control.

CE-454610-4 A CASE OF INAPPROPRIATE CLASSIFICATION OF VENTRICULAR FIBRILLATION AS SINUS TACHYCARDIA

Accurate differentiation between SVT and malignant ventricular tachyarrhythmias in ICDs is augmented with the use of device specific SVT discriminators. However, these enhancements rely on nonprogrammable algorithms that on occasion may be responsible for inappropriate withholding of VT/VF therapy. It is important to understand the reason for rhythm misclassifications so that opportunities for improvement in ICD programming can be identified. N/A A 46-year-old man with ischemic cardiomyopathy, severe left ventricular dysfunction, left bundle branch block, prior VF arrest, AF on amiodarone therapy with a Medtronic Claria CRT-D suffered a sudden cardiac arrest at home. ICD parameter settings are noted in Table. ICD electrograms showed initial monomorphic VT with cycle length 340 ms which was treated with burst anti-tachycardia pacing that resulted in a slower VT below the VT detection rate of 162 bpm. This was sustained for 5 minutes until the rhythm devolved to VF and met the criteria for VT/VF event using the combined count number of intervals to detect (CCNID, Figure). SVT discrimination was applied as the median V-V interval was greater than the programmed SVT limit of 260 ms due to occasional undersensing. The SVT discrimination feature is designed to confirm 1:1 AV conduction using pre-specified criteria. The algorithm then relies on a simultaneous sinus tachycardia (ST) count that is established using an analysis of expected RR intervals and successive PR intervals concurrently calculated. A minimum ST count of 6 was fulfilled leading to classification of the event as sinus tachycardia and withholding for VT/VF therapy (Figure). Hierarchy of sinus tachycardia in the SVT discrimination logic withholds application of waveform analysis. Criteria for VT/VF event was met 1 minute later again based on CCNID. A 36J shock was delivered unsuccessfully terminating the rhythm. Ongoing VF was undersensed in the presence of high output post shock pacing. This case illustrates several failures of tachyarrhythmia detection leading to a tragic failure of ICD therapy. Algorithm features such as the minimum requirements for 1:1 AV conduction, sinus tachycardia counter, and hierarchy of the SVT discrimination feature to withhold waveform analysis led to inappropriate withholding of therapy for VF. Understanding elements of these complex algorithms may be helpful for individualizing device program and in future development of additional SVT discrimination enhancements.

PO-05-070 ENDOCARDIAL RADIOFREQUENCY ABLATION OF VT STORM IN CARDIOGENIC SHOCK PATIENTS WITH MECHANICAL CIRCULATORY SUPPORT

Ventricular tachycardia (VT) storm in the setting of cardiogenic shock requiring mechanical support (MCS) carries a high mortality rate. Limited data exist in the literature using VT ablation as a treatment strategy in this cohort of patients. We aim to evaluate the outcome of patients receiving ablation in VT storm complicated by cardiogenic shock requiring MCS, as well as assess predictors for poor outcomes. This is a single-center, retrospective cohort study in patients with refractory VT and cardiogenic shock on MCS, undergoing endocardial ablation from 2015 to 2022. Complete substrate isolation with high output pacing within the scar, followed by stimulation protocols, was used to confirm substrate isolation and the success of ablation. Patients’ demographic and outcome data was obtained from chart review. The PAINESD score, a scoring system to predict early post-procedural mortality of VT ablation, was calculated for each patient. Peak lactate levels recorded during the procedure and preoperative invasive hemodynamic measurements were also taken into consideration. A total of 37 patients with VT storm and concomitant cardiogenic shock on MCS were included. The average age was 61.7 years old, 94.7% were men, with a mean left ventricular ejection fraction of 17.3%, and the average PAINESD score was 24.9. The type of mechanical support utilized is listed in Table 1. Twenty-one were discharged alive, 8 patients (21.6%) with long-term LVAD support, and 13 (35.1%) after weaning support, while 16 patients (43.2%) didn’t survive the index hospitalization (Figure 1). The PAINESD score between those who survived and those who died was not significantly different (25.3 vs. 24.3, p = 0.31). The survivor group had a significantly higher procedure success rate (76.2% vs. 35.3%, p=0.018), higher mean pulmonary artery pulsatility index (PAPI) (2.7 vs. 1.4, p = 0.005), and lower mean intraoperative peak lactic acid level (1.1 vs. 3.5 mmol/L, p = 0.027). Ablation for medication refractory ventricular arrhythmia in cardiogenic shock is efficacious in facilitating mechanical support weaning in a large proportion of the cohort. The absence of right ventricular dysfunction as measured by PAPI, intraoperative lactic acid level, and acute procedure success, as measured by VT inducibility at the end of the procedure, predict the short-term outcome, while the PAINESD score demonstrated weak differentiating power in this moribund, high-risk cohort.

PO-03-019 ECHOCARDIOGRAPHIC OUTCOMES OF HIS BUNDLE AND LEFT BUNDLE BRANCH AREA PACING: A SINGLE CENTER EXPERIENCE

Traditional right ventricular apical pacing is associated with risk of pacing induced cardiomyopathy (PICM), atrial fibrillation, and heart failure. Conduction system pacing (CSP) via the His or left bundle branch area (HBP, LBBAP) may mitigate or even prevent the development of these complications. To evaluate the effects of CSP on cardiac function as measured by standard 2D-echocardiography. Consecutive patients undergoing HBP or LBBAP implantation between Feb 2014 and July 2022 at Virginia Commonwealth University were analyzed. Ejection fraction (EF), left ventricular diastolic dimension (LVIDd), left ventricular systolic dimension (LVIDs), tricuspid regurgitation severity, and mitral regurgitation severity were compared pre- and post- CSP. Only patients with echo data at 90 days or greater from time of implant were included. A total of 340 patients with CSP had echocardiographic data available. Mean clinical follow up time was 810 days from implant, and median time until post-implant EF was 483 days (IQR 324-763). 77 had reduced EF (<50%) at baseline. Pacing burden exceeded 20% across the cohort. The mean pre- and post- CSP implantation EF in the overall group was 53.8% ±10.9% vs 54.7% ±9.1% (p=0.08). Mean pre- and post- CSP implant LVIDd was 4.59±0.73cm vs 4.37 ±0.72 cm (p<0.001). Mean pre- and post- CSP implant LVIDs was 3.23± 0.79cm vs 3.05± 0.76cm (p<0.001). TR and MR severity were unchanged after pacemaker implantation. In the subset of patients with reduced EF, mean pre-implant EF was 37% ±9.4% and post-implant EF was 47% ±11.6% (p<0.001). Mean pre-implant LVIDd was 5.02cm ±0.86cm and post-implant LVIDd was 4.60cm ±0.75cm (p<0.001). Mean pre-implant LVIDs was 4.05cm ±1.0cm and post-implant this dropped to 3.44cm ±0.96 (p<0.001). CSP via HBP or LBBAP is not associated with PICM in patients requiring high ventricular pacing burdens. In patients with a reduced EF, it may significantly improve systolic function along with positive structural remodeling.

PO-04-060 FOUND WITH SOUND: INTRACARDIAC ECHOCARDIOGRAPHY CORRELATED WITH MEDIUM-OUTPUT PACING TO AVOID PHRENIC NERVE INJURY WITH RIGHT ATRIAL ABLATION

Catheter ablation within the right atrium can be limited by proximity to the phrenic nerve and potential for hemi diaphragmatic paralysis. High output pacing is frequently employed to map phrenic position relative to endocardium, particularly in relation to the superior vena cava and the right superior pulmonary vein. The use of intracardiac echocardiography (ICE) in correlation with lower output pacing to rigorously map the course of the right phrenic nerve along the right atrium has not been previously described. We describe a case of incessant right atrial tachycardia successfully mapped and ablated close to the phrenic nerve using a combination of ICE imaging and medium-output pacing to rigorously map the phrenic nerve. n/a An 18-year-old man with incessant atrial tachycardia was referred for repeat ablation following unsuccessful attempt at ablation at an outside institution. Prior ablation was limited by proximity to the phrenic nerve and transient phrenic nerve palsy with cryoablation at the mid crista terminalis. Epicardial access to deflect the phrenic nerve was anticipated. Atrial tachycardia was mapped endocardially prior to obtaining epicardial access. An ICE catheter was advanced to the SVC and used to identify the phrenic nerve. The course of the phrenic nerve was rigorously mapped with ICE and integrated into the CARTO navigational system (Biosense Webster). Pacing along the course of the phrenic nerve was performed at 10 mA to further refine the course of the phrenic nerve within the SVC and right atrium. Regions in close anatomic proximity to the phrenic nerve with loss of pace-capture correlated with sites of physiologic effusion, where pericardial fluid was concentrated and separation of the phrenic nerve from the visceral epicardium was noted. After mapping the phrenic nerve, endocardial ablation of atrial tachycardia was successfully performed in the absence of phrenic nerve injury without the need for epicardial access. Phrenic nerve injury may be prevented by rigorous mapping of the phrenic nerve within the right atrium using intracardiac ultrasound with medium-output pacing.

PO-04-094 RELEVANCE OF MICROBUBBLE FORMATION WITH PULSED FIELD ABLATION SHOWING IRREVERSIBLE ELECTROPORATION IN A CANINE MODEL

With ablation using a saline flow catheter tips, occasionally microbubbles will be seen, either from excessive heating or steam pops. The occurrence and implications of microbubble formation with PFA/IRE ablation has not been determined. This study aim was to clarify the means of microbubble during PFA/IRE ablation. Therefore, a total of 4 dogs underwent evaluation with the delivery of 34 ablated lesions in the right and left atrium. During PFA/IRE ablation, we monitored by the ICE imaging whether microbubble formation occurred. With these, microbubbles were seen in 82% of deliveries. The microbubbles were class I in 25 %, class II in 25 %, and class III in 50 %. There appeared to be no untoward effect of class I microbubbles. However, with the others, a suggested biophysical property was seen. In those with catheter positioning directly perpendicular to the endocardial surface, microbubbles were less common. On the other hand, with more parallel tip positioning, or with lowere contact force, microbubbles could reach the class II or III level. These were different than past studies showing simple heat related microbubbles. With PFA the heat is not present. Nevertheless, the process of electrophoresis appeared to create the microbubbles to a greater extent than the irrigation catheter’s flow. The concern with this is a decrease in the effectiveness of delivery as judged by high-density mapping. With this study, no actual perforations were seen, but there was an energy loss with the electrophoretic effects. Actually, in gross pathology, the lesion length and width ranged from 16.5 to 24.1 mm and from 11.9 to 21.8 mm in the RA. Class II or III microbubbles are readily seen in PFA/IRE ablation. These appear to be different from that seen with irrigation-tip catheters. The marked occurrence of microbubbles suggests an electrophoretic process, which like incomplete contact could result in a substantial loss of energy rendering ablation lesions less effective. Even with enough contact PFA/IRE, the effect could be substantial. While few complications are seen with PFA/IRE ablation, the marked electrophoretic effect producing microbubbles, also seen with high output pacing could result in a diminution of the actual lesion formation as judged by histology.

Role of localized repolarization and conduction heterogeneities in ventricular arrhythmias and sudden cardiac death

Recent clinical studies have indicated the presence of localized tissue abnormalities in sudden cardiac death (SCD) survivors without apparent structural heart disease, including idiopathic ventricular fibrillation (VF) and J-wave Syndromes. The origin of these abnormalities, showing distinct electrical features on contact mapping, and mechanisms of associated arrhythmias are still a matter of debate. To determine the respective role of localized repolarization and conduction heterogeneities in vulnerability to arrhythmias and SCD, and to characterize their specific electrical signatures. Optical mapping was performed on porcine right ventricular models of either local (i) repolarization shortening, (ii) conduction slowing, or (iii) micro-structural heterogeneity which were created by locally perfusing (i) pinacidil (20 μM n = 13) or (ii) flecainide (2 μM n = 13) via an epicardial catheter (branch of right coronary artery), or (iii) by local epicardial tissue destruction through radiofrequency application (9 micro lesions 30W 1 sec n = 13). Pseudo-ECG were assessed and the number of induced and spontaneous arrhythmias were quantified and mapped in each preparation. An HD grid mapping catheter was used to record bipolar electrograms (n = 5 in each group). Electrograms were normal in model (i), but showed local fragmentation in 40% of preparations in model (ii) with greater effects observed at high pacing frequencies (3 Hz). In model (iii), the structural substrate alone increased the width and number of peaks in the electrograms, and addition of flecainide (2 μM) in this model induced pronounced fragmentation (≥ 3 peaks and ≥ 70ms duration) in 100% of the cases. Arrhythmogenicity was significantly increased in models (i) and (ii) which presented 82% and 45% more spontaneous arrhythmias (P < 0.0001 and 0.05 vs. baseline) and a reduced pacing frequency threshold to induce arrhythmias (−69% and −50%, P < 0.001 vs. baseline). In these models, the frequency of spontaneous activity was increased (+411% P < 0.01 and +181% P < 0.05 vs. baseline) and originated near the heterogeneous area. Microstructural substrates have the most pronounced impact on electrograms, especially when combined with sodium channel blockers, while repolarization heterogeneities do not lead to electrogram fragmentation but are associated with the highest prevalence of spontaneous arrhythmias. Both heterogeneities show increased ectopic activity.

Analysis of Deactivation of 18,650 Lithium-Ion Cells in CaCl2, Tap Water and Demineralized Water for Different Insertion Times.

The deployment of battery-powered electric vehicles in the market has created a naturally increasing need for the safe deactivation and recycling of batteries. Various deactivating methods for lithium-ion cells include electrical discharging or deactivation with liquids. Such methods are also useful for cases where the cell tabs are not accessible. In the literature analyses, different deactivation media are used, but none include the use of calcium chloride (CaCl2) salt. As compared to other media, the major advantage of this salt is that it can capture the highly reactive and hazardous molecules of Hydrofluoric acid. To analyse the actual performance of this salt in terms of practicability and safety, this experimental research aims to compare it against regular Tap Water and Demineralized Water. This will be accomplished by performing nail penetration tests on deactivated cells and comparing their residual energy against each other. Moreover, these three different media and respective cells are analysed after deactivation, i.e., based on conductivity measurements, cell mass, flame photometry, fluoride content, computer tomography and pH value. It was found that the cells deactivated in the CaCl2 solution did not show any signs of Fluoride ions, whereas cells deactivated in TW showed the emergence of Fluoride ions in the 10th week of the insertion. However, with the addition of CaCl2 in TW, the deactivation process > 48 h for TW declines to 0.5-2 h, which could be an optimal solution for real-world situations where deactivating cells at a high pace is essential.

Initial Experiences of Left Bundle Branch Area Pacing in Daegu, South Korea – New Procedure with Familiar Tools

Implantation of a permanent pacemaker is a safe and effective treatment for symptomatic bradycardia. Conventionally, ventricular lead is placed at the right ventricular (RV) muscles. Therefore, this causes interventricular dyssynchrony, and long-term high RV pacing (RVP) burden is associated with an increased risk of heart failure and atrial fibrillation. Hence, attempts to directly pace the cardiac conduction system have been made, and finally, a technique called left bundle branch area pacing (LBBAP) has emerged. In our country, the clinical experience of LBBAP is in the early stages. Especially, LBBAP using standard stylet-driven leads (SDL), a major procedural method performed in our country, is also in the early stages, and there are only a few reports about this method worldwide. Herein, we are reporting our initial experiences of LBBAP with SDL. Compared to conventional RVP performed during the same period, LBBAP required an initial learning period a more extended procedure, and fluoroscopy time. However, the paced QRS duration was significantly shorter in the LBBAP group (LBBAP group 120.6 ± 13.0 msec, RVP group 165.2 ± 16.0 msec, &lt;i&gt;p&lt;/i&gt; &lt; 0.001). It is fascinating that simply adding a ventricular lead delivery sheath can create a whole new outcome, even at centers that are only familiar with the standard tools. Our experience will be helpful in arrhythmia centers that aim to start LBBAP for the first time.

Artificial intelligence: what it is and what it can do for dentists

Artificial intelligence (AI) is an increasingly relevant topic for dental clinicians, with AI applications entering the clinical arena at a high pace. This article outlines what AI is, how it works, what its application fields are, but also what challenges the profession faces now and in the future. Computer vision, language processing, simulation and precision dentistry are the main fields where AI is, or will be, applied in dentistry. The ability to be generalizable to external data sources, be accurate, useful and easy to explain are the main cornerstones of AI for health applications. Clinicians should be able to appraise AI applications before integrating them in their daily workflow. AI will be useful for synthesizing an increasing amount of data in dentistry, allowing more automated, efficient and precise care. Certain tools will also facilitate patient communication and documentation. Dentists should critically evaluate AI against certain quality criteria and standards. CPD/Clinical Relevance: It is important to be aware of the applications of artificial intelligence in dentistry.

Radiofrequency catheter ablation for improving myocardial work in patients with ventricular pre-excitation.

Previous studies have not consistently found significant improvements in left ventricular ejection fraction or global longitudinal strain (GLS) after radiofrequency catheter ablation (RFCA) in patients with ventricular pre-excitation. The aim of this study was thus to explore the effects of RFCA on left ventricular function in patients with ventricular pre-excitation using a new noninvasive echocardiographic method of myocardial work. A total of 34 patients with ventricular pre-excitation who underwent RFCA and 18 healthy controls were prospectively included in this study. Before and after participants underwent RFCA, electrocardiographic and echocardiographic data of the patients were collected at resting and pacing heart rates (HRs) of 100 beats per minute (bpm) and 120 bpm (controlled by high right atrial pacing during the procedure). Clinical data of the healthy controls at resting HR were also collected. A self-controlled paired sample t test was used to compare the differences before and after participants underwent RFCA. After participants underwent RFCA, the global wasted work (GWW) of the included patients decreased (resting HR: 165.3±68.8 vs. 92.6±42.5 mmHg%, P<0.001; HR of 100 bpm: 276.3±121.2 vs. 187.9±96.0 mmHg%, P<0.001; HR of 120 bpm: 323.9±126.7 vs. 181.0%±74.3 mmHg%. P<0.001), while the global work efficiency (GWE) increased (resting HR: 91.5%±3.8% vs. 94.9%±1.6%; P<0.001; HR of 100 bpm: 87.0%±5.2% vs. 91.0%±3.3%, P<0.001; HR of 120 bpm: 85.0%±5.1% vs. 90.3%±3.7%, P<0.001). In patients with ventricular pre-excitation, impaired GWW and GWE can be improved with RFCA. In clinical practice, noninvasive myocardial work assessment can be used in patients with ventricular pre-excitation.

Inequality Dynamics in Urban Manipur, India: A Decomposition Analysis.

The high pace of urbanization in Manipur being confined to the valley regions has attracted much attention to researchers to explore the intra-state dynamics of urban inequality in the state. This study examines the role of spatial factors in determining consumption inequality in the state, especially in urban areas considering the unit-level National Sample Survey data from different rounds. Also, the Regression-Based Inequality Decomposition is estimated to understand the role played by relevant household characteristics in explaining the inequality patterns in urban Manipur. The study observes an increasing trend of Gini coefficient for the overall state despite its slow per-capita growth. While Gini measures of consumption have an overall increasing trend in the economy between 1993 and 2011, and inequality level in rural areas is greater than in urban areas in 2011-2012. This is in contrast to the overall Indian phenomenon. Also, the state per capita income is 43% lower than the all-India average in 2019-2020 at 2011-2012 prices. Within-component (both within-district and within-sector) is the major contributor to overall consumption inequality. The decomposition-based regression analysis shows that most of the estimated regression coefficients are statistically significant. Factors like age, possession of land, and regular salary earner in a household contribute to enhancing the level of total inequality of the average MPCE. This paper suggests that in order to avoid the negative consequences of rising consumption inequality in Manipur, a justiciable land redistribution policy, improving the level of education, and creating employment opportunities are necessary.

Innovation Practices and Performance of Islamic Banks in Nairobi-Kenya

Purpose: The dominant feature of the modern financial system is a high pace of innovation practices, both in terms of their number and value. Thus, it is important to analyze their influence on the financial system. The current study aimed at determining the effect of innovation practices on the financial performance of Islamic banks in Kenya. Specifically, the study sought to determine the influence product innovation practices, process innovation practices, technological innovation practices and market innovation practices on the organizational performance of Islamic banks in Kenya. This study was informed by the following theories and models: the innovation diffusion theory of innovation, the Henderson-Clark model of innovation, the Task Technology Fit theory of innovation and the Shareholder’s Wealth Maximization (SWM) Theory.&#x0D; Methodology: The study adopted a descriptive research design and targeted 3 Islamic banks in Kenya with a total of 142 managers. The sample selection was scientifically guided using the Yamane (1967) simplified formula to calculate the sample size of 105 respondents. The study used structured questionnaires to collect the data. In order to ascertain how valid and reliable the questionnaires are, a pilot study was carried out. Descriptive statistics was used to collect summary statistics including means and standard deviations while inferential statistics helped in measuring the causal relationship between the variables and included correlation and regression analysis. The generation of the statistics was through SPSS program (v.25.0). The study employed both figures and tables to present the results of the study.&#x0D; Findings: The results established that product innovation practices, process innovation practices, technological innovation practices and market innovation practices positively and significantly affect the organizational performance of Islamic commercial banks in Kenya. This is shown by respective beta values of 0.398, 0.311, 0.443 and 0.295 and respective significant values of 0.002, 0.009, 0.000 and 0.01.&#x0D; Unique contribution to theory, practice and policy: The results bears the implications that increasing each of the variable with one unit results to increase in organizational performance levels of Islamic commercial banks with respective beta values. The study recommends the Islamic commercial banks operating in Kenya to enhance their product innovation, process innovation, technological innovation and market innovation practices since the practices positively and significantly affects organizational performance.

Frequency of the multi and extensively drug-resistant Salmonella Typhi in a health care facility

Background: Antibiotic resistance is increasing against Salmonella Typhi (S. Typhi), causative agent of enteric fever, at a very high pace in Pakistan. The objective of this study was to evaluate the emergence of multi and extensively drug resistant Salmonella Typhi among suspected patients in a public health care facility in Lahore.&#x0D; Patients and methods: 5cc blood samples from the patients with high grade fever (&gt;38°C), vomiting and bradycardia (heart rate 84 bpm) were collected from laboratory of Arif Memorial Teaching Hospital, Lahore over six months (August 2020-January 2021), After informed consent, questionnaire were filled and total 97 samples were taken from suspected patients and screened for Salmonella Typhi by using Typhidot IgG/IgM by ELISA kit (one step typhoid fever) for S. Typhi. Gram staining, culture and biochemical testing was performed for confirmation. Antibiotic susceptibility testing was used to evaluate the emergence of antibiotic resistance. Statistical analysis was performed by using SPSS 20.0, software. Chi square test was used,&#x0D; Results: Total 55 (56.7%) samples out of 97 (100%) were reported positive for Salmonella Typhi. Antimicrobial susceptibility testing results indicated that 6 samples were resistant to more than one antibiotic commonly called as multidrug resistant, 44 samples were extensively drug resistant and 5 samples were nonresistant/sensitive to selected antibiotics. Highest resistance was reported against Ampicillin (51 samples (92.7%) and Co-trimoxazole (50 samples (90%)). Resistance against Moxifloxacin and Tobramycin, Ciprofloxacin, Ceftriaxone Cefuroxime and Cefotoxime, Cefxime, Levofloxacin, Salbactum, Imepenum and Amikain was 47 (85.4%), 46 (83.6%), 45 (81.81%), 44 (80%), 37 (67.2%), 32 (58.18%), 14 (45%) and 9 (16.3%) respectively. Lowest resistance was reported against Meropenum 5 (9%) and Azithromycin 1 (1%).&#x0D; Conclusion: It is concluded that the monitoring of MDR and XDR must be performed by all clinical microbiology/pathology laboratories to implement effective measures to reduce the emergence of antimicrobial resistance.