Pulsed field ablation (PFA) is a nonthermal ablation modality that achieves myocardial ablation through irreversible electroporation and has been associated with a reduced risk of collateral tissue injury. Phrenic nerve injury is uncommon with PFA, and persistent injury has rarely been described. A 61-year-old woman with symptomatic persistent atrial fibrillation refractory to anti-arrhythmic drug therapy underwent catheter ablation using the PulseSelect™ PFA system (Medtronic, Minneapolis, MN, USA). Circumferential PFA applications were delivered to all four pulmonary veins, followed by additional applications to the posterior left atrial wall to achieve posterior wall isolation. A total of 61 pulsed field energy applications were delivered, and the entrance and exit blocks of the pulmonary veins and posterior wall were confirmed. The procedure was otherwise uncomplicated. Several hours post-procedure, the patient developed new-onset dyspnea. Chest radiography demonstrated elevation of the right hemidiaphragm consistent with right phrenic nerve palsy. Conservative management was initiated, with gradual symptomatic improvement. However, follow-up imaging at 3 months demonstrated persistent right hemidiaphragmatic elevation. This case demonstrates that phrenic nerve palsy may occur following pulmonary vein and posterior wall isolation using PFA. Continued awareness of this potential complication and careful post-procedural follow-up are warranted as clinical experience with PFA continues to expand.
This case highlights an important electroanatomic mapping clue that electrophysiologists should be aware of when ablating focal atrial arrhythmias.
Previous reports have established the occurrence of atrioventricular (AV) nodal re-entrant tachycardia (AVNRT) exhibiting fixed AV ratios (most commonly 1:1, but also 2:1 or higher grade) or fixed/alternating ventriculoatrial ratios (eg, 1:1, 2:1, 3:2, 4:3, or higher grade). In contrast, the manifestation of an irregularly irregular rhythm during sustained AVNRT combined with a lower common pathway Wenckebach periodicity is exceedingly rare. We formally present a case demonstrating this unusual and complex electrophysiological phenomenon.
Para-Hisian accessory pathways (PHAPs) remain among the most challenging substrates for catheter ablation because of their close anatomical relationship to the atrioventricular (AV) conduction system and the consequent risk of iatrogenic AV block. The non-coronary cusp (NCC) has emerged as a valuable alternative when right-sided ablation is ineffective or associated with an unacceptable risk of injury to the His bundle. We report the case of a 23-year-old man who presented with pre-excited atrial fibrillation. Electrophysiological study localized an anteroseptal/para-Hisian accessory pathway. Electroanatomical mapping identified the earliest ventricular activation at the para-Hisian region; however, multiple irrigated radiofrequency applications from the right atrial septum failed to eliminate pre-excitation because of the close proximity to the His bundle. A retrograde aortic approach to the NCC was subsequently undertaken using three-dimensional electroanatomical mapping integrated with intracardiac echocardiography. Mapping within the NCC demonstrated an accessory pathway potential with atrioventricular fusion and ventricular activation preceding delta-wave onset by 20 ms. Radiofrequency delivery at this site resulted in elimination of pre-excitation within 3 s while preserving normal AV conduction. No recurrence of pre-excitation or impairment of AV nodal conduction was observed during post-ablation assessment. This case supports the NCC as a safe and effective alternative target when conventional right-sided ablation is unsuccessful or poses a significant risk of AV conduction injury.
The increasing use of cardiac implantable electronic devices has led to a rise in transvenous lead extractions (TLEs). The most common indications for TLE are infections and lead malfunction. Over time, leads develop fibrotic encapsulation that makes extraction difficult and increases the risk of myocardial injury. Given the thin myocardial wall, particularly in the right atrial appendage and right ventricular apex, the use of advanced powered tools near the lead tip is contraindicated, posing additional challenges. Electrosurgical energy (EE) has been explored as an adjunct to manual extraction to facilitate safe lead tip removal. This study compares the efficacy and safety of cut and coagulation modes of EE using a porcine tissue model and reports its clinical application in a human case. In the porcine model, the cut mode achieved rapid separation of the lead tip but resulted in deeper tissue penetration. In contrast, the coagulation mode (fulguration setting) enabled controlled dissection with minimal depth of penetration without any collateral injury. The application of the coagulation mode during an actual lead extraction with a dwell time of 8 years in a human patient resulted in complete removal with no postoperative complications. These findings suggest that the coagulation mode of EE offers a safer and more controlled technique for lead tip extraction.
The electrogram morphology and its timing within the ventricular tachycardia (VT) cycle enable electrophysiologists to infer the location of the scar and its relationship to the VT circuit. This becomes particularly important in the presence of double-entrance or double-exit configurations, where distinguishing the critical isthmus from a noncritical bystander is essential.
A 26-year-old woman at 34 weeks' gestation presented with out-of-hospital cardiac arrest due to ventricular fibrillation. Her electrocardiogram (ECG) showed sinus rhythm with a short P-R interval and an unusually fractionated delta wave. The delta wave was positive in leads I and V2-V6, isoelectric in V1, and negative in inferior leads. An electrophysiology study revealed antegrade accessory pathway conduction with the earliest ventricular activation in the posteroseptal region. Three radiofrequency (RF) ablation procedures, including attempts with pulsed field ablation, were ultimately unsuccessful. Cardiac computed tomography angiography revealed a diverticulum of the middle cardiac vein (MCV). Irrigated RF ablation within the diverticulum successfully eliminated the accessory pathway conduction. We propose that multiple fibers of the coronary sinus or the MCV muscular coat may interface via the diverticulum with the ventricle, leading to multiple wavefronts of ventricular pre-excitation, and that the resultant delta-wave fractionation may allow identification of such an epicardial accessory pathway.
Implantable cardioverter-defibrillators (ICDs) are life-saving devices used to prevent sudden cardiac death. Two newer types of ICDs-the extravascular ICD (EV-ICD) and the subcutaneous ICD (S-ICD)-offer alternatives to traditional transvenous ICDs. Additionally, efforts are being made to introduce defibrillation and pacing interventions through a single device called the modular cardiac rhythm management system (mCRM). This review compares the EV-ICD and S-ICD based on currently available clinical data, focusing on their safety and performance. Additionally, we review modular ICD systems, which integrate leadless pacing with defibrillation. We conducted a comprehensive literature search of PubMed and ScienceDirect, focusing on articles demonstrating the clinical outcomes of EV-ICDs and S-ICDs as well as modular systems. However, we found that sufficient studies are not available to determine the clinical efficacy and safety outcomes of EV-ICDs and the mCRM. Additionally, comparative studies between EV-ICDs and S-ICDs are still required to determine their relative roles in the field of electrophysiology, with the goal of empowering clinicians to understand these emerging technologies to support better patient care decision-making.
Prior studies have demonstrated links between systemic inflammation and cardiac arrhythmias. However, evidence on the association between inflammatory biomarkers and resting premature atrial contractions (PACs) or premature ventricular contractions (PVCs) in a national sample of older adults remains limited. Using biomarker data from the Midlife in the United States (MIDUS 3) study (2017-2022), we conducted non-parametric univariate analyses to assess associations between inflammatory markers-specifically, interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor-α (TNF)-α, C-reactive protein (CRP), and fibrinogen-and baseline electrocardiographic (ECG) findings categorized as normal, PVCs, or PACs. We conducted a subsequent multivariate analysis of covariance adjusted for age, waist-hip ratio (WHR), and creatinine, the only confounders showing significant associations. A total of 699 participants were included, 395 (57%) of whom were women, with a mean age of 65.7 years (standard deviation, 9.6 years). The Kruskal-Wallis tests demonstrated significant associations of ECG pattern with IL-6 (median, normal 0.98 vs. PVCs 1.06 vs. PACs 1.40; P = .006) and IL-8 (12.4 vs. 13.99 vs. 13.13; P = .028). No significant associations were found for IL-10, TNF-α, CRP, or fibrinogen (P > .05). After adjustment for age, WHR, and creatinine, the ECG pattern remained significantly associated with IL-6 and IL-8 (P = .034). Elevated IL-6 and IL-8 levels are associated with resting PVCs and PACs in older adults. WHR and renal function also represent significant related factors that warrant consideration in future pathophysiological research.
Micra™ retrieval techniques involve snaring the proximal knob; however, device orientation can hinder knob access. Unorthodox retrieval methods included a two-snare approach and a "snare-in-snare" technique. We describe a single-tine-based snaring approach of a Micra™ leadless pacemaker (Medtronic, Minneapolis, MN, USA) 4 days after implantation due to loss of capture. An 89-year-old man with a history of chronic kidney disease, hypertension, and transcatheter aortic valve replacement complicated by complete heart block underwent Micra™ implantation. Four days later, he presented with syncope. Interrogation showed an elevated capture threshold with intermittent loss of capture. Chest radiography confirmed an upside-down orientation in the right ventricular outflow tract. A 27-Fr outer-diameter Aveir™ Introducer Sheath (Abbott, Chicago, IL, USA) was advanced via the right femoral vein. The Aveir™ leadless pacemaker (Abbott) was implanted in a lower septal position. Multiple attempts to snare the Micra™ device's retrieval knob using the Aveir™ Retrieval Catheter (Abbott) and a Goose Neck Snare (20-mm loop diameter, 102 cm; Covidien [Medtronic], Dublin, Ireland) through a steerable sheath failed. A figure-of-eight stitch was placed around the introducer sheath and left untied. The snare engaged a partially free tine. Gentle traction confirmed secure engagement, and controlled traction disengaged the remaining tines. The device was withdrawn into the inferior vena cava but could not be pulled into the sheath due to angulation. The entire system was removed, and the groin stitch was tied. However, the Micra™ dislodged into the groin subcutaneous tissue. Iliofemoral angiography via internal jugular vein access confirmed no extravasation, and the device was explanted through a small groin incision using forceps. Percutaneous retrieval of a Micra™ leadless pacemaker, with short dwell time, is feasible using a one-tine-based snaring technique when snaring of the proximal retrieval knob fails. The tine is durable; however, caution should be exercised.
Left bundle branch area pacing (LBBAP) has become adopted in recent years to achieve improved ventricular synchrony and reduce the risk of pacing-induced cardiomyopathy. It is a potential alternative to standard right ventricular pacing. However, long-term clinical data regarding lead integrity and longevity are still lacking. Several case reports have highlighted the risk of distal conductor lead failure. In this case, we report late distal lead conductor failure with the Solia S60 lead (Biotronik, Berlin, Germany) intended for left bundle branch area two years after initial implant.
Short QT syndrome (SQTS) is a rare inherited cardiac channelopathy disease resulting from mutations in potassium channels. It has been associated with several dysrhythmias, including ventricular tachycardia, ventricular fibrillation, atrial fibrillation, and atrial flutter. We report, for the first time, a case of a 19-year-old man presenting with recurrent syncope due to SQTS concomitant with sick sinus syndrome, who underwent implantation of an implantable cardioverter-defibrillator.
Ventricular tachycardia (VT) is a fatal arrhythmia, often managed with implantable cardioverter-defibrillators (ICDs). Many patients, however, present without an ICD. The role of catheter ablation in this high-risk group is unclear, particularly for short-term in-hospital outcomes. We assessed associations between ablation and in-hospital outcomes among ICD-naive VT patients using a large national dataset. We conducted a retrospective study using the National Inpatient Sample (2016-2021), identifying adult hospitalizations with VT. Patients with prior ICDs or ICD implantation during the same admission were excluded. The cohort was divided into those who underwent catheter ablation versus those managed without ablation. Multivariable logistic regression and 1:1 propensity score matching (PSM) adjusted for demographic, clinical, and hospital factors. The primary outcome was in-hospital mortality; secondary outcomes included ST-elevation myocardial infarction (STEMI), sepsis, major adverse cardiac events (MACEs) (death, STEMI, or cardiogenic shock), cardiogenic shock, tamponade, mechanical circulatory support (MCS), acute heart failure, and prolonged hospitalization (≥7 days). Of 2,214,424 VT hospitalizations, 32,640 (1.5%) underwent catheter ablation. After PSM (n = 12,668), ablation was associated with significantly lower rates of in-hospital mortality (3.17% vs. 8.98%; P < .001), STEMI (6.82% vs. 18.83%; P < .001), sepsis (3.38% vs. 10.34%; P < .001), and MACEs (15.82% vs. 28.40%; P < .001). However, ablation was associated with higher rates of cardiac tamponade (1.78% vs. 0.43%; P < .001), cardiogenic shock (9.14% vs. 7.12%; P < .001), and MCS use (5.04% vs. 3.71%; P < .001). Rates of acute heart failure and prolonged hospitalization were comparable. In ICD-naive VT patients, catheter ablation was associated with improved in-hospital survival and fewer complications, albeit with higher procedural risks.
Bradyarrhythmias with syncope during pregnancy present a complex and multifaceted challenge for both patients and health care providers. When device implantation is indicated for bradyarrhythmia-associated syncope during pregnancy, the procedure should be performed with particular attention to minimizing fluoroscopy exposure to ensure maternal and fetal safety. A 29-year-old woman at 15 weeks of gestation with sinus pauses presented with recurrent syncopal episodes. The patient underwent Micra™ AV leadless pacemaker implantation (Medtronic, Minneapolis, MN, USA) with a radiation exposure of 26.5 mGy and a total fluoroscopy time of 2 min, which is generally considered a negligible dose during pregnancy, based on the recommendations of the National Council on Radiation Protection and Measurements. In pregnant patients, a leadless pacemaker may offer a viable alternative to conventional pacing, primarily due to its reduced radiation exposure, shorter procedure time, minimally invasive approach, absence of transvenous leads, and lower risk of site infection.
Class IC anti-arrhythmic drugs are primarily preferred for the rhythm control of atrial fibrillation (AF). In cases where ablation fails, the appropriate rhythm-control strategy is still unclear. In our study, we aimed to evaluate the efficacy of flecainide, propafenone, and radiofrequency ablation (RFA) as rhythm-control strategies in paroxysmal AF patients with failed cryoballoon ablation (CBA). In this cross-sectional study, 1120 patients who underwent CBA for paroxysmal AF between 2017 and 2024 were screened. Within this patient group, 230 patients with recurrent AF (≥3 months) after CBA were identified. A total of 120 patients (40 cases per treatment) who underwent rhythm control and received flecainide, propafenone, or RFA were finally included in the study. Study participants were then divided into three groups, receiving flecainide (group I), propafenone (group II), or RFA (group III). All patients were followed up for at least 1 year for AF recurrence, which was confirmed in 52 (43.2%) patients. The AF recurrence rates in groups I, II, and III were 35%, 75%, and 20%, respectively. Although the frequency of AF recurrence in groups I and III was statistically similar (P > .05), it was significantly lower in these groups than that in group II (P < .05). Group I patients were significantly more likely to use β-blockers than group II or III patients (P < .05). Patients with AF recurrence had a larger left atrial (LA) diameter and greater propafenone use. The number of patients who used flecainide and underwent RFA was lower in the AF recurrence group. In logistic regression analysis, LA diameter was found to be an independent predictor of AF recurrence (P = .002). In conclusion, based on the findings of our study, flecainide therapy can be used with an acceptable success rate in patients with recurrent AF after CBA.
Discrete prepotentials (PPs) mapped within the aortic sinuses of Valsalva are considered reliable targets for the ablation of idiopathic premature ventricular complexes (PVCs) and ventricular tachycardias. A critical conduction time is required for the PVC to manifest, as evidenced by a distinct isoelectric segment between the discrete PPs and the ventricular electrograms, consistent with the limitations imposed by the local refractoriness of the tissue at the exit site.
