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Second degree atrioventricular block: Mobitz type I (Wenckebach block)

William H Sauer, MD
Section Editor
Leonard I Ganz, MD, FHRS, FACC
Deputy Editor
Brian C Downey, MD, FACC


Atrioventricular (AV) block is defined as a delay or interruption in the transmission of an impulse from the atria to the ventricles due to an anatomic or functional impairment in the conduction system. The conduction disturbance can be transient or permanent, with conduction that is delayed, intermittent, or absent. Commonly used terminology includes:

First degree AV block – Delayed conduction from the atrium to the ventricle (defined as a prolonged PR interval of >200 milliseconds) without interruption in atrial to ventricular conduction.

Second degree AV block – Intermittent atrial conduction to the ventricle, often in a regular pattern (eg, 2:1, 3:2), or higher degrees of block, which are further classified into Mobitz type I (Wenckebach) and Mobitz type II second degree AV block.

Third degree (complete AV) block – No atrial impulses conduct to the ventricle.

High-grade AV block – Two or more consecutive blocked P waves.

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Literature review current through: Nov 2017. | This topic last updated: Sep 28, 2017.
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  1. Wenckebach, KF . Zur Analyse der unregelmässigen Pulses. Ztschr klin Med 1899; 36:181.
  2. Mobitz, W . Über die unvollständige Störung der Erregungsüberleitung zwischen Vorhof und Kammer des menschlichen Herzens. Z Gesamte Exp Med 1924; 41:180.
  3. JOHNSON RL, AVERILL KH, LAMB LE. Electrocardiographic findings in 67,375 asymptomatic subjects. VII. Atrioventricular block. Am J Cardiol 1960; 6:153.
  4. Brodsky M, Wu D, Denes P, et al. Arrhythmias documented by 24 hour continuous electrocardiographic monitoring in 50 male medical students without apparent heart disease. Am J Cardiol 1977; 39:390.
  5. Dickinson DF, Scott O. Ambulatory electrocardiographic monitoring in 100 healthy teenage boys. Br Heart J 1984; 51:179.
  6. Meytes I, Kaplinsky E, Yahini JH, et al. Wenckebach A-V block: a frequent feature following heavy physical training. Am Heart J 1975; 90:426.
  7. Viitasalo MT, Kala R, Eisalo A. Ambulatory electrocardiographic recording in endurance athletes. Br Heart J 1982; 47:213.
  8. Zeppilli P, Fenici R, Sassara M, et al. Wenckebach second-degree A-V block in top-ranking athletes: an old problem revisited. Am Heart J 1980; 100:281.
  9. Zehender M, Meinertz T, Keul J, Just H. ECG variants and cardiac arrhythmias in athletes: clinical relevance and prognostic importance. Am Heart J 1990; 119:1378.
  10. Young D, Eisenberg R, Fish B, Fisher JD. Wenckebach atrioventricular block (Mobitz type I) in children and adolescents. Am J Cardiol 1977; 40:393.
  11. Stein R, Medeiros CM, Rosito GA, et al. Intrinsic sinus and atrioventricular node electrophysiologic adaptations in endurance athletes. J Am Coll Cardiol 2002; 39:1033.
  12. Meimoun P, Zeghdi R, D'Attelis N, et al. Frequency, predictors, and consequences of atrioventricular block after mitral valve repair. Am J Cardiol 2002; 89:1062.
  13. Oliveira E, Ribeiro AL, Assis Silva F, et al. The Valsalva maneuver in Chagas disease patients without cardiopathy. Int J Cardiol 2002; 82:49.
  14. Friedman HS, Gomes JA, Haft JI. An analysis of Wenckebach periodicity. J Electrocardiol 1975; 8:307.
  15. Denes P, Levy L, Pick A, Rosen KM. The incidence of typical and atypical A-V Wenckebach periodicity. Am Heart J 1975; 89:26.
  16. Josephson, ME. Atrioventricular Conduction. In: Clinical Cardiac Electrophysiology, 4th, Lippincott, Philadelphia 2008. p.93.
  17. Neumar RW, Otto CW, Link MS, et al. Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010; 122:S729.
  18. Epstein AE, DiMarco JP, Ellenbogen KA, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices): developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons. Circulation 2008; 117:e350.
  19. Vardas PE, Auricchio A, Blanc JJ, et al. Guidelines for cardiac pacing and cardiac resynchronization therapy. The Task Force for Cardiac Pacing and Cardiac Resynchronization Therapy of the European Society of Cardiology. Developed in collaboration with the European Heart Rhythm Association. Europace 2007; 9:959.
  20. Shaw DB, Gowers JI, Kekwick CA, et al. Is Mobitz type I atrioventricular block benign in adults? Heart 2004; 90:169.
  21. Coumbe AG, Naksuk N, Newell MC, et al. Long-term follow-up of older patients with Mobitz type I second degree atrioventricular block. Heart 2013; 99:334.