Left Bundle Branch Block
Figure 1: ECG Strip
A left bundle branch block occurs when "the normal direction of septal depolarization is reversed (becomes right to left), as the impulse spreads first to the RV via the right bundle branch and then to the LV via the septum." The reversed direction of depolarization produces deep S waves in the right precordial leads (V1) and tall R waves in the lateral leads (V6).
Table 1: ECG Characteristics
- The presence of a LBBB often indicates the presence of significant underlying heart disease.
- A LBBB alone can also cause the heart to work less efficiently.
- LBBB occurs mostly in older adults.
Figure 2: ECM Analysis, Record 109
Additional Example of a LBBB
Figure 3: Record 214
- LBBB [Online image]. (2011). Retrieved July 19, 2016, from http://en.ecgpedia.org/index.php?title=Textbook
- Left Bundle Branch Block. (n.d.). Retrieved July 27, 2016, from http://lifeinthefastlane.com/ecg-library/basics/left-bundle-branch-block/
- Bundle Branch Block. (n.d.). Retrieved July 27, 2016, from http://www.practicalclinicalskills.com/ekg-reference-guide-details?lessonID=39
- Fogoros, R. N. (n.d.). What Does It Mean to Have a Left Bundle Branch Block? Retrieved August 08, 2016, from https://www.verywell.com/left-bundle-branch-block-lbbb-1745784
- MIT-BIH Arrhythmia Database. (1980). Retrieved June, 2016, from https://physionet.org/physiobank/database/mitdb/
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