Left bundle branch block

A left bundle branch block (LSB ) is a disorder of the conduction system of the heart. Characteristic of the disorder is a conduction delay in the left bundle branch. The diagnosis is made by ECG.


A left bundle branch block is defined as an extension of the interval from the onset of the QRS complex to the point of final Negativitätsbewegung (GNB ) ( largest Negativitätsbewegung, also known as Upper transition point ( OUP ) refers ) in V 5 or V 6 ( the left chest leads ) on at least 0.06 seconds. If the criterion of a left bundle branch block satisfies (extension of GNB at least 0.06 seconds in V 5 or V 6 ) defines the QRS width, the difference between an incomplete left bundle branch block ( QRS width up to and including 0.12 seconds ) and a complete left bundle branch block ( QRS duration > 0.12 sec).


Hemodynamic the left bundle branch block results in a hunting phenomenon of the blood in the contraction. A complete left bundle branch block represents a pathological ( disease-related ) findings dar. The cause is found frequently coronary heart disease, arterial hypertension, or cardiomyopathy.


The left bundle branch block is to be regarded as opposed to the right bundle branch block as serious as the left ventricle makes the major part of the pumping action of the heart.

The ECG is no longer safe usable in the presence of a left bundle branch block for the diagnosis of heart attack, as a consecutive Repolarisationsstörung occurs. The ST segment is highly modified to produce an interpretation in terms of a Ischämiehinweises is not easy. With Sgarbossa criteria the probability of acute myocardial ischemia can be estimated. In normal ECG preliminary investigation, a freshly occurred LSB may suggestive of acute myocardial ischemia, eg an acute heart attack to be. Together with the corresponding clinical symptoms (chest pain, shortness of breath ) or increasing the cardiac-specific laboratory markers ( troponin, creatine kinase ) is an indication for prompt invasive diagnosis as part of cardiac catheterization.


The following forms can be distinguished:

  • Left bundle branch block
  • Left anterior hemiblock
  • Linksposteriorer hemiblock
  • Disease in cardiology