Second-Degree AV Block Mobitz I (Wenckebach) vs Second-Degree AV Block Mobitz II: clinical and ECG differences
Side-by-side comparison of Second-Degree AV Block Mobitz I (Wenckebach) and Second-Degree AV Block Mobitz II according to the MioAtlas 3D cardiac simulator model.
Findings by layer and diagnostic parameters
| Layer / Finding | Second-Degree AV Block Mobitz I (Wenckebach) | Second-Degree AV Block Mobitz II |
|---|---|---|
| Clinical summary |
Progressive prolongation of the PR interval in successive beats until a P wave fails to conduct (blocked P wave). The pause that follows is shorter than two normal cycles, and the cycle then restarts. Almost always located within the AV node; usually benign and reversible (vagal hypertonia, inferior STEMI, drugs). |
Sudden failure of AV conduction with an intermittent dropped P wave WITHOUT prior PR interval prolongation. The block is located in the His bundle or bundle branches (infranodal). High risk of progression to complete infrahisian block and Stokes-Adams syncope; absolute indication for permanent pacemaker implantation. |
| Heart rate |
68 bpm (min: 50, max: 90) |
55 bpm (min: 40, max: 75) |
| QRS duration |
90 ms |
130 ms |
| Mechanism |
bloqueo |
bloqueo |
| AV conduction |
wenckebach |
variable |
| Key leads |
II |
II, V1 |
Sources and bibliographic references
Second-Degree AV Block Mobitz I (Wenckebach)
- Anderson RH, Yanni J, Boyett MR, Chandler NJ, Dobrzynski H. The anatomy of the cardiac conduction system . Clin Anat (2009) . DOI: 10.1002/ca.20700
- Kligfield P, Gettes LS, Bailey JJ, et al. Recommendations for the standardization and interpretation of the electrocardiogram: Part I: The electrocardiogram and its technology . Circulation (2007) . DOI: 10.1161/CIRCULATIONAHA.106.180200
- Surawicz B, Childers R, Deal BJ, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part III: Intraventricular conduction disturbances . Circulation (2009) . DOI: 10.1161/CIRCULATIONAHA.108.191095
Second-Degree AV Block Mobitz II
- Anderson RH, Yanni J, Boyett MR, Chandler NJ, Dobrzynski H. The anatomy of the cardiac conduction system . Clin Anat (2009) . DOI: 10.1002/ca.20700
- Kligfield P, Gettes LS, Bailey JJ, et al. Recommendations for the standardization and interpretation of the electrocardiogram: Part I: The electrocardiogram and its technology . Circulation (2007) . DOI: 10.1161/CIRCULATIONAHA.106.180200
- Surawicz B, Childers R, Deal BJ, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part III: Intraventricular conduction disturbances . Circulation (2009) . DOI: 10.1161/CIRCULATIONAHA.108.191095