User:Mr. Ibrahem/Left bundle branch block
| Left bundle branch block | |
|---|---|
 | |
| ECG characteristics of a typical LBBB showing wide QRS complexes with abnormal morphology in leads V1 and V6. | |
| Specialty | Cardiology, emergency medicine |
| Symptoms | None[1] |
| Duration | Long-term[1] |
| Causes | Unknown, dilated cardiomyopathy, amyloidosis[1] |
| Diagnostic method | Electrocardiogram (ECG)[1] |
| Differential diagnosis | Intraventricular conduction delay, artificial pacemaker, run of PVCs[1] |
| Treatment | Based on underlying disorder[1] |
| Frequency | Common[1] |
Left bundle branch block (LBBB) is a type of electrical conduction abnormality of the heart seen on the electrocardiogram (ECG).[1] In and of itself, it results in no symptoms.[1] The condition is generally permanent.[1]
Causes include dilated cardiomyopathy, such as may occur following a heart attack, valvular heart disease, or heart failure and amyloidosis.[1] Though some cases occurs without any specific cause.[1] The underlying mechanism involves abnormal conduction down both anterior and posterior left fascicles of the His-Purkinje system.[1]
Diagnosis requires four conditions: the rhythm is supraventricular, the QRS is greater than 120 ms, lead V1 has a QS or a small r with a large S wave, and lead V6 has a notched R and no Q wave.[1] When the QRS duration is less than 120 ms, but the other criteria are present, it is called an incomplete LBBB.[1] New onset LBBB together with chest pain was previously, but is no longer considered, a STEMI equivalent.[2] Rather it is recommended the Sgarbossa criteria be applied.[1]
No specific treatment is generally required.[1] Management is directed at the underlying cause, which determines the outcomes.[1] LBBB is common, affected about 1 in 1,000 people.[1] About 33% of those with heart failure are affected.[1] Those affected are not permitted to fly an aircraft in the United States or United Kingdom.[1]
References[edit]
- ^ a b c d e f g h i j k l m n o p q r s t u Scherbak, D; Hicks, GJ (January 2020). "Left Bundle Branch Block". PMID 29489192.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Roberts, David. Mastering the 12-Lead EKG. Springer Publishing Company. p. 434. ISBN 978-0-8261-8194-7. Archived from the original on 2021-08-28. Retrieved 2020-12-30.