Right bundle branch block

Right bundle branch block
ECG characteristics of a typical RBBB showing wide QRS complexes with a terminal R wave in lead V1 and slurred S wave in lead V6.
Classification and external resources
Specialty Cardiology
ICD-10 I45.1
ICD-9-CM 426.4
DiseasesDB 11620
eMedicine ped/2500

A right bundle branch block (RBBB) is a heart block in the electrical conduction system.[1]

During a right bundle branch block, the right ventricle is not directly activated by impulses travelling through the right bundle branch. The left ventricle however, is still normally activated by the left bundle branch. These impulses are then able to travel through the myocardium of the left ventricle to the right ventricle and depolarize the right ventricle this way. As conduction through the myocardium is slower than conduction through the Bundle of His-Purkinje fibres, the QRS complex is seen to be widened. The QRS complex often shows an extra deflection which reflects the rapid depolarisation of the left ventricle followed by the slower depolarisation of the right ventricle.

In most cases right bundle branch block has a pathological cause though it is also seen in healthy individuals.[2]

Diagnosis

Normal electrical conduction system of the heart (Schematic). All myocardial segments are excited almost simultaneously (purple staining).
Conduction in RBBB (Schematic): With a blockage in the right bundle branch (red), the left ventricle is excited in time (purple), while the excitation of the right ventricle takes a detour via the left bundle branch (blue arrows).

The criteria to diagnose a right bundle branch block on the electrocardiogram:

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.

A mnemonic to distinguish between ECG signatures of left bundle branch block (LBBB) and right, is WiLLiaM MaRRoW; i.e., with LBBB, there is a W in lead V1 and an M in lead V6, whereas, with RBBB, there is an M in V1 and a W in V6.

Causes

An atrial septal defect is one possible cause of a right bundle branch block.[4] In addition, a right bundle branch block may also result from Brugada syndrome, right ventricular hypertrophy, pulmonary embolism, ischaemic heart disease, rheumatic heart disease, myocarditis, cardiomyopathy or hypertension.

Epidemiology

Prevalence of RBBB increases with age.

Treatment

The underlying condition may be treated by medications to control hypertension or diabetes, if they are the primary underlying cause. If coronary arteries are blocked, an invasive coronary angioplasty may relieve the impending RBBB.[5]

See also

References

  1. "Conduction Blocks 2006 KCUMB". Retrieved 2009-01-20.
  2. Da Costa D, Brady WJ, Edhouse J (March 2002). "Bradycardias and atrioventricular conduction block". BMJ. 324 (7336): 535–8. doi:10.1136/bmj.324.7336.535. PMC 1122450Freely accessible. PMID 11872557.
  3. "Lesson VI - ECG Conduction Abnormalities". Retrieved 2009-01-07.
  4. Goldman, Lee (2011). Goldman's Cecil Medicine (24th ed.). Philadelphia: Elsevier Saunders. pp. 400–401. ISBN 1437727883.
  5. "Right Bundle Branch Block". www.symptoma.com. Retrieved 2015-08-13.
This article is issued from Wikipedia - version of the 11/8/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.