Cheema, Kamal Preet

Background: Patients with D-transposition of the great arteries and atrial switch have a high incidence of atrial arrhythmias. We sought to analyze the arrhythmia substrate, ablation strategies, and outcomes for catheter ablation in this population. Methods: An in-depth analysis of all clinical and procedural data in patients with D-transposition of the great arteries, atrial baffles, and atrial arrhythmia ablation was performed. Results: A cohort of 32 patients (72% male, mean age 38±7 years) underwent ablation for non-AV nodal reentrant tachycardia atrial arrhythmias, and 4 patients underwent AV nodal reentrant tachycardia ablation. Cavotricuspid isthmus flutter (CTI-flutter) was the most common arrhythmia, encountered in 75% of patients, followed by scar-related intraatrial reentrant tachycardia (non-CTI intraatrial reentrant tachycardia, 53%) and focal atrial tachycardia (focal atrial tachycardia, 6%). Among the 32 patients, 26 underwent 31 procedures at our institution. For patients with prior outside intervention, the index ablation at our institution revealed CTI-dependent flutter in 3/5 cases. However, redo ablation after an index ablation with demonstrated bidirectional CTI block revealed different/new arrhythmia substrates (80% non-CTI intraatrial reentrant tachycardia, 40% focal atrial tachycardia). Achieving bidirectional block across the CTI often required ablating on both sides of the baffle (retroaortic access, 81%; using a baffle leak, 11.5%; or transbaffle puncture, 7.7%). Combined approaches were necessary in 19% to reach the critical tissue. Acute procedural success was 81%, and recurrence was documented in 58% of patients. Despite recurrence, clinical arrhythmia burden was significantly reduced post-ablation ( P <0.001), with rare episodes, amenable to antiarrhythmic therapy. Redo ablation was required in 5 (19%) patients and uncovered new arrhythmia substrates. AV nodal reentrant tachycardia ablation also required transbaffle approaches in 3/4 patients. Conclusions: CTI-dependent flutter was the most common arrhythmia in patients with Dextro-Transposition of the Great Arteries and atrial switch. Transbaffle approaches were often necessary, and, provided that bidirectional CTI block was achieved at the index ablation, late recurrence was due to different arrhythmia mechanisms. Despite recurrence, ablation was associated with significant clinical improvement.

Abstract Introduction Placing a magnet over a Permanent Pacemaker (PPM) or Implanted Cardioverter-Defibrillator (ICD) may cause the device to pace asynchronously or inhibit tachyarrhythmia detection, respectively, potentially preventing delivery of electrical shocks. Manufacturers for masks used with positive airway pressure devices have started using magnets in place of more traditional headgear clips to connect the headgear to mask. Mask manufactures do not list presence of a PPM/ICD as a contraindication to use of a mask with magnet but do recommend keeping the mask some distance away from PPM/ICD. A published case series describes two patients with magnet response events captured during PPM/ICD interrogation that correlated with nightly use of CPAP. The authors were able to replicate the response by placing the mask with magnet directly over the patient’s pulse generate site. Although we advise all patients with implanted device to avoid use of masks with magnets, select patients refuse to stop using mask with magnets regardless of our policy. We, therefore, started offering these patients referral for PPM/ICD interrogation to evaluate for an interaction between mask with magnet and PPM/ICD as next best alternative. Methods We retrospectively reviewed all patients (n=10) referred for routine PPM/ICD interrogation to test whether the mask with magnet interacted with PPM/ICD when mask on face as during normal use (i.e., simulated normal use) or magnetic area of mask placed directly over the PPM/ICD (i.e., direct contact). Results Although no interaction was detected in any patient (n=10) with simulated normal use (0 %), one interaction was documented with direct contact (10 %). Conclusion Although simulated normal use of masks with magnets did not demonstrate any interactions, it is concerning that one patient (10 % of patients) demonstrated an interaction with direct contact of magnetic area of mask over the PPM/ICD. It is not uncommon for patients to remove a mask during the night while sleeping. This preliminary data along with the published case series calls for further research and increased awareness of this potential interaction for both sleep and cardiac health care providers. Support (If Any) None