An Unexpected Pacemaker Response to Catheter Ablation: Failure of Pacing Pulse Delivery During Asynchronous Pacing Mode.

Radiofrequency (RF) ablation can be a source of electromagnetic interference (EMI) for cardiovascular implantable electronic devices (CIEDs). The response of CIEDs to this type of EMI can be variable and unpredictable. We report a case with an uncommon response where there was a failure to deliver pacing pulses to both atrial and ventricular pacing leads during RF ablation close to the atrial lead even when the pacemaker was set to pace asynchronously. We also explain the mechanism behind this unusual pacemaker response.

Impact of fixation mechanism and helix retraction status on right ventricular lead extraction.

Background: The impact of lead fixation mechanism on extractability is poorly characterized. Objective: We aimed to compare the technical difficulty of transvenous lead extraction (TLE) of active vs passive fixation right ventricular (RV) leads. Methods: A total of 408 patients who underwent RV TLE by a single expert electrophysiologist at Oregon Health & Science University between October 2011 and June 2022 were identified and retrospectively analyzed; 331 (81%) had active fixation RV leads and 77 (19%) had passive fixation RV leads. The active fixation cohort was further stratified into those with successfully retracted helices (n = 181) and failed helix retraction (n = 109). A numerical system (0-9) devised using 6 procedural criteria quantified a technical extraction score (TES) for each RV TLE. The TES was compared between groups. Results: Helix retraction was successful in ≥55% of active fixation TLEs. The mean TES for active-helix retracted, active-helix non-retracted, and passive fixation groups was 1.8, 3.5, and 3.7, respectively. The TES of the active-helix retracted group was significantly lower than those of the active-helix non-retracted group (adjusted P < .01) and the passive fixation group (adjusted P < .01). There was no significant difference in TES between the passive fixation and active-helix non-retracted groups in multivariate analysis (P = .18). The TLE success rate of the entire cohort was >97%, with a major complication rate of 0.5%. Conclusion: TLE of active fixation leads where helical retraction is achieved presents fewer technical challenges than does passive fixation RV lead extraction; however, if the helix cannot be retracted, active and passive TLE procedures present similar technical challenges.

Adaptive Cardiac Resynchronization Therapy Effect on Electrical Dyssynchrony (aCRT-ELSYNC): A randomized controlled trial.

BACKGROUND: Adaptive cardiac resynchronization therapy (aCRT) is known to have clinical benefits over conventional CRT, but the mechanisms are unclear. OBJECTIVE: Compare effects of aCRT and conventional CRT on electrical dyssynchrony. METHODS: A prospective, double-blind, 1:1 parallel-group assignment randomized controlled trial in patients receiving CRT for routine clinical indications. Participants underwent cardiac computed tomography and 128-electrode body surface mapping. The primary outcome was change in electrical dyssynchrony measured on the epicardial surface using noninvasive electrocardiographic imaging before and 6 months post-CRT. Ventricular electrical uncoupling (VEU) was calculated as the difference between the mean left ventricular (LV) and right ventricular (RV) activation times. An electrical dyssynchrony index (EDI) was computed as the standard deviation of local epicardial activation times. RESULTS: We randomized 27 participants (aged 64 ± 12 years; 34% female; 53% ischemic cardiomyopathy; LV ejection fraction 28% ± 8%; QRS duration 155 ± 21 ms; typical left bundle branch block [LBBB] in 13%) to conventional CRT (n = 15) vs aCRT (n = 12). In atypical LBBB (n = 11; 41%) with S waves in V5-V6, conduction block occurred in the anterior RV, as opposed to the interventricular groove in strict LBBB. As compared to baseline, VEU reduced post-CRT in the aCRT (median reduction 18.9 [interquartile range 4.3-29.2 ms; P = .034]), but not in the conventional CRT (21.4 [-30.0 to 49.9 ms; P = .525]) group. There were no differences in the degree of change in VEU and EDI indices between treatment groups. CONCLUSION: The effect of aCRT and conventional CRT on electrical dyssynchrony is largely similar, but only aCRT harmoniously reduced interventricular dyssynchrony by reducing RV uncoupling.

Transvenous management of cardiac implantable electronic device late lead perforation.

INTRODUCTION: Late lead perforation (LLP), defined as perforation ≥30 days from cardiac implantable electronic device implant, is a rare diagnosis and little data exist regarding management practices and outcomes. The purpose of this study was to evaluate the occurrence, safety, and efficacy of transvenous management of clinically significant LLP. METHODS: The electronic medical records of a single-center tertiary hospital were reviewed for all patients who were referred for LLP or its sequelae. RESULTS: Eleven consecutive patients were identified from October 2011 to December 2018 with clinically significant LLP. Patients most often presented with pericardial symptoms with the exception of one asymptomatic patient. The median time from lead implant to intervention for LLP was 246 days. Nine patients were managed with an initial transvenous approach, with one requiring sternotomy (lead 6.3 years old). Two patients had a surgical approach, one performed at an outside hospital with subsequent death and another had a mini-thoracotomy, but the lead was removed percutaneously with no surgical repair. In this small cohort, there was no association between the lead extending beyond the parietal pericardium and surgical repair (P = .99). CONCLUSION: Our single-center experience suggests that LLP can be initially managed with a cautious transvenous approach in most patients, but intraprocedural ultrasound for pericardial monitoring and a rescue plan with immediate surgical back up is mandatory.

Dexmedetomidine Sedation for Paroxysmal Supraventricular Tachycardia Ablation Is Not Associated With Alteration of Arrhythmia Inducibility.

BACKGROUND: Dexmedetomidine (Dex) is an attractive agent for procedural sedation due to its unique pharmacodynamic profile, specifically affording predictable sedation without concurrent respiratory depression. However, Dex has previously been reported to prevent or terminate arrhythmias. The purpose of this study was to investigate paroxysmal supraventricular tachycardia (PSVT) inducibility and homeostatic stability during electrophysiology studies (EPSs) and ablation when a standardized Dex protocol was used as the primary sedation agent. METHODS: We performed a retrospective review of 163 consecutive procedures for PSVT ablation that received Dex as the primary sedative with adjunct fentanyl and midazolam boluses (DEX-FENT-MIDAZ). This cohort was compared to 163 consecutive control procedures wherein strictly fentanyl and midazolam were used for sedation. The primary outcome reviewed was PSVT inducibility assessed before ablation. Reviewed secondary outcomes included level of sedation and intraprocedure hemodynamics and oxygenation. RESULTS: The arrhythmia profiles of the DEX-FENT-MIDAZ and control cohorts were very similar. The overall incidence of a "negative" EPSs in which arrhythmia was not induced was 24% in the DEX-FENT-MIDAZ group and 26% in the control group (P = .7). Unintended deep sedation was significantly less with DEX-FENT-MIDAZ (4.3% vs 27%; P ≤ .0001). However, DEX-FENT-MIDAZ use was associated with a higher incidence of intraprocedure hypotension. CONCLUSIONS: Dex sedation during EPSs is not associated with a reduction in PSVT inducibility. The therapeutic utility of Dex during EPS arises from the predictable sedation Dex affords but is associated with an increased incidence of intraprocedure hypotension.

Effectiveness of dual external direct current cardioversion for initial cardioversion in atrial fibrillation.

INTRODUCTION: Dual external direct current cardioversion (dual-DCCV) is a rhythm control strategy for persistent atrial fibrillation (AF), involving simultaneous delivery of two shocks from two defibrillators. The long-term effectiveness of this approach has not been studied in the biphasic cardioversion era. METHODS: Seventy-seven consecutive patients at a single center were identified to receive dual-DCCV at the time of their initial cardioversion for AF, when maximum output standard external direct current cardioversion failed in two vectors. Logistic regression was used to analyze risk factors for dual-DCCV in a historical control group of 77 patients undergoing standard cardioversion and Cox proportional hazard models were used to compare time to AF recurrence. RESULTS: The dual-DCCV group had a significantly larger body mass index (BMI), but similar AF duration and left atrial size as controls. Multivariable logistic regression revealed that BMI and absence of prior paroxysmal AF were risk factors for dual-DCCV (P < 0.05). There was no difference observed between dual-DCCV and control groups (adjusted hazard ratio = 0.57; P = .12) after adjusting for number of shocks and age. Transient hypoxia was the only acute complication in either group (P > .999). CONCLUSION: Dual-DCCV appears to be a safe and effective cardioversion strategy for patients with AF. The need for dual-DCCV in the treatment of AF appears to be influenced more by body habitus than atrial substrate.

Electromagnetic Interference with Protocolized Electrosurgery Dispersive Electrode Positioning in Patients with Implantable Cardioverter Defibrillators.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: Electromagnetic interference from monopolar electrosurgery may disrupt implantable cardioverter defibrillators.Current management recommendations by the American Society of Anesthesiologists and Heart Rhythm Society are based on expert clinical opinion since there is a paucity of data regarding the risk of electromagnetic interference to implantable cardioverter defibrillators during surgery. WHAT THIS ARTICLE TELLS US THAT IS NEW: With protocolized electrosurgery dispersive electrode positioning in patients with implantable cardioverter defibrillators, the risk of clinically meaningful electromagnetic interference was 7% in above-the-umbilicus noncardiac surgery and 0% in below-the-umbilicus surgery. In cardiac surgery, clinically meaningful electromagnetic interference with use of an underbody dispersive electrode was 29%.Despite protocolized dispersive electrode positioning, the risk of electromagnetic interference in above-the-umbilicus surgery is high, supporting recommendations to suspend antitachycardia therapy when monopolar electrosurgery is used above the umbilicus.With protocolized dispersive electrode positioning, the risk of electromagnetic interference in below-the-umbilicus surgery is negligible, implying that suspending antitachycardia therapy might be unnecessary in these cases.With an underbody dispersive electrode, the risk of electromagnetic interference in cardiac surgery is high. BACKGROUND: The goal of this study was to determine the occurrence of intraoperative electromagnetic interference from monopolar electrosurgery in patients with an implantable cardioverter defibrillator undergoing surgery. A protocolized approach was used to position the dispersive electrode. METHODS: This was a prospective cohort study including 144 patients with implantable cardioverter defibrillators undergoing surgery between May 2012 and September 2016 at an academic medical center. The primary objectives were to determine the occurrences of electromagnetic interference and clinically meaningful electromagnetic interference (interference that would have resulted in delivery of inappropriate antitachycardia therapy had the antitachycardia therapy not been programmed off) in noncardiac surgeries above the umbilicus, noncardiac surgeries at or below the umbilicus, and cardiac surgeries with the use of an underbody dispersive electrode. RESULTS: The risks of electromagnetic interference and clinically meaningful electromagnetic interference were 14 of 70 (20%) and 5 of 70 (7%) in above-the-umbilicus surgery, 1 of 40 (2.5%) and 0 of 40 (0%) in below-the-umbilicus surgery, and 23 of 34 (68%) and 10 of 34 (29%) in cardiac surgery. Had conservative programming strategies intended to reduce the risk of inappropriate antitachycardia therapy been employed, the occurrence of clinically meaningful electromagnetic interference would have been 2 of 70 (2.9%) in above-the-umbilicus surgery and 3 of 34 (8.8%) in cardiac surgery. CONCLUSIONS: Despite protocolized dispersive electrode positioning, the risks of electromagnetic interference and clinically meaningful electromagnetic interference with surgery above the umbilicus were high, supporting published recommendations to suspend antitachycardia therapy whenever monopolar electrosurgery is used above the umbilicus. For surgery below the umbilicus, these risks were negligible, implying that suspending antitachycardia therapy is likely unnecessary in these patients. For cardiac surgery, the risks of electromagnetic interference and clinically meaningful electromagnetic interference with an underbody dispersive electrode were high. Conservative programming strategies would not have eliminated the risk of clinically meaningful electromagnetic interference in either noncardiac surgery above the umbilicus or cardiac surgery.

Successful Ablation of Epicardial Premature Ventricular Complexes Near the Great Cardiac Vein from the Left Ventricular Endocardium Despite Predictors of Failure.

Mapping and ablating premature ventricular complexes (PVCs) that originate near the great cardiac vein (GCV) and anterior interventricular vein (AIV) can pose several challenges related to the advancement and positioning of catheters within these veins, the delivery of effective lesions, and the risk of collateral injury to the left coronary arteries and left phrenic nerve. When ablation of these PVCs from inside the GCV/AIV is not possible, a systematic assessment of nearby vantage points, such as the left coronary cusp (LCC) and left ventricular (LV) endocardial breakout site, should be considered, in addition to the performance of a more invasive epicardial ablation procedure via a percutaneous pericardial puncture or thoracotomy. Several electrocardiographic, anatomic, and electrogram timing features have been shown to predict the likelihood of successful ablation from a non-epicardial site, such as the LCC or LV endocardium, but none of these spots is considered to be a perfect location. The case described here in this report is a demonstration of a safe and successful ablation of GCV PVCs from the LV endocardial breakout site using adequate power and lesion duration, even when the site was 17 mm away from the putative origin, and some previously described electrocardiographic and electrogram-based predictors of success suggested the outcome would not be positive.