Left bundle branch block
| Left bundle branch block | |
|---|---|
| Classification and external resources | |
 ECG characteristics of a typical LBBB showing wide QRS complexes with abnormal morphology in leads V1 and V6. |
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| ICD-10 | I44.4 - I44.7 |
| DiseasesDB | 7352 |
| eMedicine | ped/2501 |
Left bundle branch block (LBBB) is a cardiac conduction abnormality seen on the electrocardiogram (ECG).[1] In this condition, activation of the left ventricle is delayed, which results in the left ventricle contracting later than the right ventricle.
Contents |
[edit] EKG diagnosis
The criteria to diagnose a left bundle branch block on the electrocardiogram:
- The heart rhythm must be supraventricular in origin
- The QRS duration must be ≥ 120 ms[2]
- There should be a QS or rS complex in lead V1
- There should be a RsR' wave in lead V6.
The T wave should be deflected opposite the terminal deflection of the QRS complex. This is known as appropriate T wave discordance with bundle branch block. A concordant T wave may suggest ischemia or myocardial infarction.
[edit] Causes
Among the causes of LBBB are:
- Aortic stenosis
- Dilated cardiomyopathy
- Acute myocardial infarction
- Extensive coronary artery disease
- Primary disease of the cardiac electrical conduction system
- Long standing hypertension leading to aortic root dilatation and subsequent aortic regurgitation
[edit] Treatment
- Medical Care: Patients with LBBB require complete cardiac evaluation, and those with LBBB and syncope or near-syncope may require a pacemaker.
- Surgical Care: Some patients with LBBB, a markedly prolonged QRS, and congestive heart failure may benefit from a pacemaker, which provides rapid left ventricular contractions.
[edit] Classification
There are also partial blocks of the left bundle branch: "left anterior fascicular block" (LAFB)[3] and a "left posterior fascicular block" (LPFB).[4] This refers to the bifurcation of the left bundle branch.
[edit] See also
[edit] References
- ^ "Conduction Blocks 2006 KCUMB". http://courses.kcumb.edu/physio/blocks/index.htm. Retrieved 2009-01-20.
- ^ "Lesson VI - EKG Conduction Abnormalities". http://library.med.utah.edu/kw/ecg/ekg_outline/Lesson6/index.html#LBBB. Retrieved 2009-01-07.
- ^ x20050921122910832459 at GPnotebook
- ^ x20050921123129832459 at GPnotebook
[edit] External links
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