Rate-Dependent Bundle Branch Block: Not Only Phase 3 Exists

Alfonso Jurado Román, Juan Jimenez Jaimez, Ana Gonzalez Mansilla, Santiago De Dios Perez, Roberto Marín Asenjo, Fernando Arribas Ynsaurriaga


Rate-dependent bundle branch blocks are often related with increased heart rate(tachycardia-dependent or phase-3 bundle branch block). Less often, they arecaused by heart rate reduction (bradycardia-dependent or phase-4 bundle branchblock). Phase-3 block is the most common type of paroxysmal intraventricularconduction disturbances documented in several publications. However, few articlesdescribe phase-4 bundle branch block, and both mechanisms rarely coexist in thesame patient. We report the case of a patient admitted with acute myocardialinfarction, presenting with both tachycardia- and bradycardia-dependentparoxysmal intraventricular conduction disturbances.


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Revista argentina de cardiología. ISSN en línea 1850-3748. Argentine journal of cardiology (English ed. Online ISSN 2314-2286) Sociedad Argentina de Cardiología. Azcuénaga 980 (C1115AAD),Ciudad Autónoma de Buenos Aires, República Argentina. Tel. (54 11) 4961-6027/8/9 Fax: 4961-6020 www.sac.org.ar revista@sac.org.ar