Yasin, Omar

Abstract Background His bundle pacing aims to mimic the activation pattern of normal conduction to maintain ventricular synchrony. However, selective His capture can be challenging, and the activation sequence during His pacing may not replicate normal conduction. Purpose Compare the right ventricular (RV) and left ventricular (LV) activation pattern in sinus rhythm and His bundle pacing. Methods Baseline LV and RV map was created in sinus rhythm using Rhythmia mapping system (Boston Scientific Corporation) in canine animal model. Medtronic 3830 lead was placed near the bundle of His under fluoroscopic, intracardiac echocardiogram, and electroanatomic guidance. Conduction system capture was confirmed by observing a QRS duration <120ms and an isoelectric segment between pacing artifact and QRS on surface ECG. Repeat LV and RV activation map was obtained during His pacing. Average QRS, HV and pacing to V intervals were calculated with standard deviation. Results Mapping was performed successfully in four animals. At baseline, the average QRS duration was 44±2.6ms and HV interval was 32±4.2ms. Earliest site of myocardial activation was in the mid-septal LV region. The earliest RV myocardial activation was also at the septum closer to the apex, but later than the LV (Figure1A). With His pacing, the average QRS duration was 70±17.0ms and the average stim to V interval was 31±8.7ms. During His pacing, the earliest site of activation was in the RV septum, with an activation pattern from base to apex in both the RV and LV. Conclusion Unlike normal physiology, the activation pattern during conduction system pacing is from base to apex with earliest site in the RV. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Mayo Clinic

Abstract Aims Current electrophysiology signal recording and mapping systems have limited dynamic range (DR) and bandwidth, which causes loss of valuable information during acquisition of cardiac signals. We evaluated a novel advanced signal processing platform with the objective to obtain and assess additional information of clinical importance. Methods and results Over 10 canines, we compared intracardiac recordings within all cardiac chambers, in various rhythms, in pacing and during radiofrequency (RF) ablation across two platforms; a conventional system and the PURE EP™ [(PEP); Bio Sig Technologies, Inc., Los Angeles, CA, USA]. Recording cardiac signals with varying amplitudes were consistently and reproducibly observed, without loss of detail or introduction of artefact. Further the amplitude of current of injury (COI) on the unipolar signals correlated with the instantaneous contact force (CF) recorded on the sensing catheter in all the animals (r2 = 0.94 in ventricle). The maximum change in the unipolar COI correlated with the change in local electrogram amplitude during non-irrigated RF ablation (r2 = 0.61 in atrium). Reduction in artefact attributable to pacing (20 sites) and noise during ablation (48 sites) was present on the PEP system. Within the PEP system, simultaneous display of identical signals, filtered differently, aided the visualization of discrete conduction tissue signals. Conclusion Compared to current system, the PEP system provided incremental information including identifying conduction tissue signals, estimates of CF and a surrogate for lesion formation. This novel signal processing platform with increased DR and minimal front-end filtering may be useful in clinical practice.

AbstractIntroductionVenous stenosis is a well‐recognized complication of transvenous leads (TVLs) that is encountered during lead revisions or device upgrades. We here report the outcomes of TVL placement facilitated by fibroplasty or tunneling (TUN) procedure.MethodsWe conducted a single‐center retrospective cohort study of all patients undergoing TVL implantation requiring fibroplasty or TUN from 2005 to 2017. Medical records and procedure reports were reviewed for relevant data. Outcomes for fibroplasty and TUN to facilitate TVL placement were compared.ResultsSixty patients had fibroplasty and thirty‐five patients had a TUN procedure. There was no difference in procedure success rates between the two groups (97% fibroplasty vs. 100% TUN; p = .98). The fluoroscopy time was longer (fibroplasty = 39.7 ± 21.5 min vs. TUN = 29.2 ± 21.3 min; p = .01) and the total procedural time was shorter in the fibroplasty group (fibroplasty = 247 ± 77.8 min vs. TUN = 287 ± 77.1 min; p = .01). TUN was associated with a significantly higher incidence of acute complications (fibroplasty = 0 vs. TUN = 8; p = .002) most requiring invasive intervention and/or transfusion with blood products. Long‐term complications requiring additional device‐related procedures were comparable between the two groups (fibroplasty = 6 vs. TUN = 6; logrank p = .21).ConclusionsFor patients with venous stenosis requiring additional TVL, balloon fibroplasty is associated with similar rates of success and a significantly decreased incidence of acute complications when compared with subcutaneous TUN.

Abstract Catheter-tissue coupling is crucial for effective delivery of radiofrequency (RF) energy during catheter ablation. Force sensing catheters provide a metric of mechanical tissue contact and catheter stability, while local impedance has been shown to provide sensitive information on real-time tissue heating. The complementary use of force and local impedance during RF ablation procedures could provide an advantage over the use of one metric alone. This study evaluates a prototype ablation catheter that measures both contact force (CF) using inductive sensors and local catheter impedance (LI) using only catheter electrodes. The complementary nature was assessed with discrete lesions in vitro and an intercaval line in vivo. A force-sensing catheter with LI was evaluated in explanted swine hearts (n=14) in an in vivo swine model (n=9, 50–70kg) using investigational electroanatomical mapping software. In vitro, discrete lesions were created in ventricular tissue at a range of forces (0–40g) controlled externally. RF energy was applied at a range of powers (20W, 30W, and 40W), durations (10s-60s), and catheter orientations (0°, 45°, and 90°). Lesions were stained with TTC and measured. LI drop relative to baseline during RF in the bench studies was used to inform the in vivo study. In a separate subset of animals in vivo, an intercaval line was created in three experimental groups: LI blinded, 20Ω ΔLI, and 30Ω ΔLI. CF was maintained between 15 and 25g in all groups. All ablations were performed with a power of 30W. In the LI blinded group, all lesions were delivered for 30s. In the 20Ω ΔLI group, the investigator ablated until a 20Ω drop or 30 seconds was achieved. Likewise, in the 30Ω ΔLI, the investigator ablated until a 30Ω drop or 30 seconds was achieved. In vitro, 137 discrete ventricular lesions were created. LI drop during ablation correlated strongly with lesion depth using a monoexponential fit (R=0.84) while force time integral (FTI) did not correlate as strongly (R=0.56). In the intercaval LI blinded group, starting LI ranged from 126–163Ω with a median of 138Ω. LI drops ranged from 13Ω-44Ω, with a median of 26Ω. In the 20Ω ΔLI group, starting LI ranged from 137–211Ω with a median of 161Ω and LI drop ranged from 7Ω-35Ω, with a median of 22Ω. In the 30Ω ΔLI group, starting LI ranged from 130–256Ω with a median of 171Ω and LI drop ranged from 20Ω-52Ω, with a median of 31Ω. Notably, RF time for the LI blinded group was 13±0.1 minutes while RF time in the 20Ω ΔLI group was 6.4±1.9 minutes and 7.5±0.7 minutes in the 30Ω ΔLI group. A catheter incorporating CF-sensing and LI capabilities provides a powerful tool for RF ablation. Bench studies demonstrate a strong correlation between LI drop and lesion dimensions, which guided the use of LI in vivo. In vivo, the confirmation of stable mechanical contact and viewing of real-time LI drops enabled a significant reduction in RF time while creating a continuous intercaval line. Acknowledgement/Funding This study was funded by Boston Scientific.

Abstract Background Venous stenosis is a well-recognized complication of transvenous leads when patients require lead revisions or device upgrade. In these cases, balloon venoplasty or alternative venous access with subcutaneous tunneling can be performed. Purpose Compare the outcomes of venoplasty vs. tunneling in patients requiring additional transvenous lead implantation. Methods A single center retrospective cohort study of all patients undergoing lead implantation/revision requiring venoplasty or tunneling from 2005–2017. Chi-squared and Wilcoxon Rank-Sum tests were used to compare categorical and continuous variables. Results Ninety five patients met our inclusion criteria (60 venoplasty & 35 tunneling). There was no difference in procedure success rates (p-value=0.98). Tunneling was associated with less fluoroscopy time but higher incidence of acute complications (0% vs. 23%, p-value=0.002) most requiring invasive intervention and/or blood product transfusion. Long term outcomes were comparable and related to lead failure or infection. Outcomes for tunneling vs. venoplasty Variable Tunneling (n=35) Venoplasty (n=60) p-value Age Y 67 (23–84) 70 (29–91) 0.25 Male (%) 24 (69%) 41 (68%) 0.98 Number of existing leads 2.1 (1–4) 2.4 (0–4) 0.1 Age of oldest lead 7.0 (0–21) 7.2 (0–33) 0.73 Number of new leads 1.2 (1–3) 1.4 (1–3) 0.26 Fluoroscopy time (SD) min 29.2 (21.3) 39.7 (21.5) 0.012 Procedure success (%) 35 (100%) 55 (92%) 0.9 Acute complications (%) 8 (23%)1 0 (0%) 0.0002 Pocket hematoma/bleed 4 (11%)2 Hemothorax 2 (6%)3 Pericarditis 1 (3%) Lead compromise 1 (3%) Follow up M 18 (0–76) 28 (0–98) N/A Long term lead issues (%) 6 (17%) 10 (17%) 0.95 Long term complication requiring intervention 4 (11%) 8 (13%) N/A Procedure success: functional lead placed as a result of venoplasty or tunneling. 1Two patients required blood products. 2Two patients required invasive intervention. 3One patient required chest tube and the other ICU admission. Conclusions Balloon venoplasty is associated with similar rates of success and a less incidence of acute complications when compared subcutaneous tunneling. Acknowledgement/Funding NIH T32 Training Grant HL07111-40

Abstract Background Choosing the appropriate animal model for development of novel technologies requires an understanding of anatomy and physiology of these different models. There are little data about the characteristics of different animal models for the study of technologies used for epicardial ablation. We aimed to compare the incidence of ventricular arrhythmias during epicardial radiofrequency ablation between swine and canine models using novel epicardial ablation catheters. Methods We conducted a retrospective study using data obtained from epicardial ablation experiments performed on swine ( Sus Scrofa ) and canine ( Canis familiaris ) models. We compared the incidence of ventricular arrhythmias during ablation between swine and canine using multivariate regression analysis. Six swine and six canine animals underwent successful epicardial radiofrequency ablation. A total of 103 ablation applications were recorded. Results Ventricular arrhythmias requiring cardioversion occurred in 13.11% of radiofrequency ablation applications in swine and 9.75% in canine (relative risk: 117.6%, 95% confidence interval [CI]: 83.97‐164.69, animal‐based odds ratio [OR]: .55, 95% CI: .23‐61.33; P = .184). When adjusting for application position, duration of ablation and power, the odds of developing potentially lethal ventricular arrhythmia in swine increased significantly compared to canine (OR: 3.60, 95% CI: 1.35‐9.55; P = .010). Conclusions The swine myocardium is more susceptible to developing ventricular arrhythmias compared to canine model during epicardial ablation. This issue should be carefully considered in future studies.