Electrophysiologic Characteristics of Ventricular Arrhythmias Arising from the Aortic Mitral Continuity—Potential Role of the Conduction System

Abstract

Introduction Catheter ablation of ventricular arrhythmia (VA) at the fibrous aortic mitral continuity (AMC) has been described, yet the nature of the arrhythmogenic substrate remains unknown. Methods Procedural records of 528 consecutive patients undergoing ablation of VA at Mayo Clinic, Rochester, MN, were reviewed. The electrocardiographic and electrophysiologic characteristics of patients with successful ablation at the AMC were analyzed to characterize the underlying arrhythmogenic substrate. Results Of the 21 patients (mean age 53.2 ± 13.4 years, 47.6% male) who underwent ablation of VA at the AMC with acute success, prepotentials (PPs) were found at the ablation sites preceding the ventricular electrogram (VEGM) during arrhythmias in 13 (61.9%) patients and during sinus rhythm in 7 (53.8%) patients. VAs with PPs were associated with a significantly higher burden of premature ventricular complexes (PVCs) (26.1 ± 10.9% vs 14.9 ± 10.1%, p = 0.03), shorter VEGM to QRS intervals (9.0 ± 28.5 ms vs 33.1 ± 8.8 ms, p = 0.03), lower pace map scores (8.7 ± 1.6 vs 11.4 ± 0.8, p = 0.001), and a trend towards shorter V-H intervals during VA (32.1 ± 38.6 ms vs 76.3 ± 11.1 ms, p = 0.06) as compared to those without PP. A strong and positive correlation was found between V-H interval and QRS duration during arrhythmia in those with PPs (B = 2.11, R2 = 0.97, t = 13.7, p <0.001) but not in those without PPs. Conclusion Local EGM characteristics and relative activation time of the His bundle suggest the possibility of conduction tissue as the origin for VA arising from the fibrous AMC. Specific identification and targeting of PPs when ablating VAs at this location may improve procedural success.

Preferential Pathway Pacing within the Aortic Sinus of Valsalva: Strong Evidence for the Existence of Preferential Conduction with Different Exit Sites Traversing the Ventricular Septum

“…5 According to their report, prepotentials were seen ahead of local ventricular electrograms during sinus rhythm as well as during ventricular arrhythmias in about half of the VPC/VT cases. In our case, the isolated high frequency potential that preceded the QRS onset during VPC was recorded behind the local ventricular electrogram during sinus rhythm.…”

Disappearance of Idiopathic Outflow Tract Premature Ventricular Contractions After Catheter Ablation of Overt Accessory Pathways

“…Hai et al . suggests the possible involvement of conduction tissue remnants in the genesis of VAs arising from the fibrous AMC . The study identifies prepotentials (PPs) at the AMC preceding the ventricular electrogram in a major subgroup of patients who underwent successful OTA ablation at that specific site.…”

“…In addition, of the approximate 20% of OTAs originating outside the RVOT, a considerable number arise from special anatomical structures (e.g., AMC, aortic sinus cusp and structures around the pulmonic valve), which could make mapping and ablation procedures difficult. Although a number of reports in the literature describe the electrocardiographical and electrophysiological characteristics of VAs originating from these unique locations, the exact nature of the arrhythmogenic substrate still remains unknown in several cases. Therefore, we believe that, beside technical considerations associated with difficult anatomical locations, a significant number of ablation failures might also be attributed to incomplete understanding of the underlying arrhythmogenic mechanisms.…”

“…The most likely mechanism is considered to be catecholamine‐mediated delayed afterdepolarizations and triggered activity . However, some recent observations such as the coexistence of OT premature ventricular contraction (PVCs) with pre‐excitation or perinodal arrhythmias, such as atrioventricular nodal reentrant tachycardia (AVNRT), or others reporting an association between discrete prepotentials and successful ablation sites of VAs, might indicate a novel putative mechanism responsible for arrhythmia genesis and challenge our current understanding of the pathogenesis of outflow tract arrhythmias (OTAs) . Based on the above‐mentioned observations a subset of patients may have an unconventional arrhythmia substrate that could even connect arrhythmic origins of anatomically distant regions.…”

Analysis of Morphological Characteristics and Origins of Idiopathic Premature Ventricular Contractions Under a 12-Lead Electrocardiogram in Children with Structurally Normal Hearts

“…Precordial R-wave transition occurring before the sinus rhythm QRS wave or wide Rwave in leads V1 and V2 is considered to be of left ventricular outflow tract (LVOT) (left coronary cusp, right coronary cusp, left and right coronary cusp junction) origin. 14,15) 2) PVCs-LBBB-II: a LBBB morphology with downward main QRS wave pattern in lead V1; no or part of large R pattern of QRS in leads II, III, and aVF (similar to the type B Wolff Parkinson-White syndrome); dominant R pattern in leads I and aVL; at least one "S" or "s" wave in the inferior leads; low amplitude of QRS wave in lead aVR. This type of PVC is generally considered to be of tricuspid annulus origin.…”