Anatomic relationship between branches of the left anterior fascicle and the right sinus of Valsalva: Implications for ablation of left anterior fascicular ventricular arrhythmias

Fascicular arrhythmias can originate from the branches of the left anterior or posterior fascicles in the form of ventricular tachycardia (VT) or premature ventricular complexes (PVCs). They are characterized by a narrow QRS complex, as first described by Zipes et al. 1 Zipes D.P. Foster P.R. Troup P.J. Pedersen D.H. Atrial induction of ventricular tachycardia: reentry versus triggered automaticity. Am J Cardiol. 1979; 44: 1-8 Abstract Full Text PDF PubMed Scopus (271) Google Scholar The fascicular system as described by Tawara 2 Tawara S. Das Reizleitungenssystem des Säugetierherzens: eine anatomisch-histologische Studie über das Atrioventrikularbündel und die Purkinjeschen Fäden. Fischer, Jena1906 Google Scholar in his pioneering work “Das Reizleitungssystem des Säugetierherzens” was divided into anterior, posterior, and septal fascicles. Arrhythmias originating from the left anterior fascicle (LAF) have been described as demonstrating a narrow QRS complex with a right bundle branch block (RBBB) morphology, inferior axis, and discrete q waves in the inferior leads. Catheter ablation of these arrhythmias can be challenging because ablation may result in transient injury or permanent damage to the conduction system. 3 Kose S. Vurgun V.K. Gokoglan Y. Balli M. Kabul H.K. Clinical, electrocardiographic and electrophysiological characteristics, and catheter ablation results of left upper septal premature ventricular complexes. J Cardiovasc Electrophysiol. 2020; 31: 3251-3261 Crossref PubMed Scopus (2) Google Scholar Avoidance of iatrogenic damage to the conduction system while achieving successful elimination of PVCs originating from the conduction system is key, and one such strategy is the targeting of these arrhythmias from safer “vantage points” via an anatomic approach. Chen et al 4 Chen S. Lu X. Peng S. et al. Ablation at right coronary cusp as an alternative and favorable approach to eliminate premature ventricular complexes originating from the proximal left anterior fascicle. Circ Arrhythm Electrophysiol. 2020; 13e008173 Crossref Scopus (16) Google Scholar reported that in patients with PVCs exhibiting a very narrow QRS complex, ablation from within the right sinus of Valsalva (SV) may help to eliminate PVCs originating from the anterior fascicular system. Terminal end of retro-aortic root branch: An unrecognized origin for “proximal left anterior fascicle” premature ventricular complexes with narrow QRS durationHeart RhythmVol. 19Issue 10PreviewPremature ventricular complexes (PVCs) with narrow QRS duration, inferior frontal plane QRS axis, and right bundle branch block (RBBB) pattern generally originate from the proximal segment of the left anterior fascicle (LAF). Full-Text PDF