title: Block of the mitral-pulmonary isthmus during ablation of a single left-sided accessory pathway causing different patterns of retrograde atrial activation.
abstract: The case of a 16-year-old patient with atrioventricular tachycardia caused by a single left anterolateral accessory pathway is reported. When the patient underwent radiofrequency ablation, a lesion on the mitral annulus lateral wall produced changes in the retrograde atrial activation pattern determined by that pathway; changes ranged from a delay in depolarization of the annulus posterior portions to full left atrium counterclockwise activation. Such phenomena were probably caused by a block in the isthmus between the annulus and the lower left pulmonary vein ostium. This case illustrates the importance of the mitral-pulmonary isthmus in the process of left atrium activation, an alert to changes induced by its unintentional block during accessory pathway ablation.
authors.affiliation: Clínica de Ritmologia Cardíaca, Hospital Beneficência Portuguesa de São Paulo.
authors.forename: José Tarcísio Medeiros
authors.initials: JT
authors.lastname: de Vasconcelos
authors.forename: Eduardo Rodrigues Bento
authors.initials: ER
authors.lastname: Costa
authors.forename: Silas
authors.initials: S
authors.lastname: dos Santos Galvão Filho
authors.forename: Cecília Monteiro Boya
authors.initials: CM
authors.lastname: Barcellos
authors.forename: Jaime Giovany Arnez
authors.initials: JG
authors.lastname: Maldonado
mesh_terms: D000293:Adolescent; D016279:Atrial Function, Left / Q000502:physiology*; D017115:Catheter Ablation / Q000009:adverse effects*; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000209:etiology*; D006329:Heart Conduction System / Q000002:abnormalities; D006801:Humans; D008943:Mitral Valve / Q000503:physiopathology*; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000601:surgery*