A bundle branch block is a defect in the bundle or ungodly branch of the heart's electrical conduction system.
Video Bundle branch block
Anatomy and physiology
The electrical activity of the heart begins at the sinoatrial node (a natural pacemaker), located in the upper right atrium. Encouragement runs next through the left and right atrium and concludes at the atrioventricular node. From the AV node, the electrical impulse moves into his bundle and divides into the right and left bundle branches. The right bundle branch contains one wicked. The left bundle branch is divided into two wasik: left anterior fascicle and left posterior fascicle. Other sources divide the left bundle into three wasik branches: left anterior, posterior left, and left septal fascia. The thicker the left posterior fascicle bifurcates, with one fascicle being in the aspect of the septum. Ultimately, the falicles divide into millions of Purkinje fibers, which in turn interdigitise with the heart of the individual heart, allowing rapid, coordinated, and synchronous depolarization of the ventricles.
Maps Bundle branch block
Mechanism
When a branch of a bundle or fascicle becomes injured (by underlying heart disease, myocardial infarction, or cardiac surgery), it may stop applying proper electrical impulses. This results in an altered pathway for ventricular depolarization. Because the electrical impulse can no longer use the preferred path in the bundle, it can move through the muscle fibers in a way that slows down electrical motion and alters the propagation of the direction of the impulse. As a result, there is a loss of ventricular sync, depolarization of the ventricle lengthwise, and there may be a corresponding decrease in cardiac output. When heart failure is present, a special pacemaker can be used to reconstruct the ventricle. In theory a pacemaker like this will shorten the QRS interval, thus bringing the left and right ventricular contraction time closer together and slightly increasing the ejection fraction.
Diagnosis
Bundle branch blocks can be diagnosed when the duration of the QRS complex on the ECG exceeds 120 ms. The proper bundle branch block usually causes the last part of the QRS complex extension, and can shift the heart's axis slightly to the right. The ECG will show the R-wave terminal at lead V1 and the S wave scattered in lead I. The left bundle branch block widens the entire QRS, and in many cases shifts the heart's electrical axis to the left. ECG will show complex QS or rS in lead V1 and monophasic R wave at lead I. Another normal finding with bundle branch block is proper T wave imbalance. In other words, the T wave will be deflected in contrast to the QRS complex terminal deflection. Bundle block branches, especially the left bundle branch block, may lead to cardiac sync. The simultaneous occurrence of the left and right bundle branch blocks leads to the total AV block.
Type
Depending on the location of the defective anatomy leading to the bundle branch block, the blocks are further classified into:
- Block the right bundle branch
- Left bundle block
Left file branch block can be subdivided into:
- Left anterior fascicular block. In this case only the anterior half of the left bundle (fascicle) is involved
- Left posterior fasciculus block. Only the posterior part of the left bundle bundle is involved
Other classifications of bundle branch blocks are;
- Bifascicular blocks. This is a combination of right bundle branch block (RBBB) and left either anterior fasciculus block (LAFB) or left posterior fascicose block (LPFB)
- Block trifascicular. This is a combination of right bundle branch blocks with both left anterior fascicular blocks or left posterior fasciculus blocks together with first level AV blocks
- Block branch of Takikardia-dependent bundle
Treatment
Some people with bundle branch blocks are born with this condition. Many get it as a consequence of heart disease. People with branch blocks bundle may still be quite active, and there may not be anything more extraordinary than the abnormal appearance on their ECG. However, when bundle blocks are complex and spread in bundle systems, or are associated with additional and significant ventricular muscle damage, they may be a sign of underlying heart disease. In more severe cases, a pacemaker may be required to restore the optimal power supply to the heart muscle.
See also
- Pacemakers
- Block hearts
- First level AV block
- Second degree AV block
- Third degree AV block
References
- Cecil Textbook of Medicine. W.B. Sanders. 2004. Chapter 50; 58.
- Rakel: The Family Practice Lesson Book, 6th ed., 2002. W.B. Saunders Company. pp.Ã, 699-732.
External links
Source of the article : Wikipedia
0 Comments