Intraventricular Block: Causes

Pathogenesis (development of disease)

Intraventricular block is an excitation conduction disturbance in the ventricular musculature. According to its occurrence, the block is subdivided into right and left ventricular block (LSB), respectively. Furthermore, IV block can be subdivided into uni- to trifascicular block.

In thigh block, there is a conduction disturbance of the heart below the His bundle (Latin: fasciculus atrioventricularis). The His bundle is part of the conduction system. It lies distal to the atrioventricular node (lat. nodus atrioventricularis; “atrioventricular node“; AV node) toward the apex of the heart.

In intraventricular block, the following forms are distinguished according to the number of fascicles (substructures consisting of multiple nerve or muscle fibers) involved:

  • Unifascicular block
  • Bifascicular blocks – e.g., right bundle branch block and left anterior hemiblock.
  • Trifascicular blocks – all legs below the His bundle.

According to the localization, a distinction is made between:

  • Left bundle branch block (LSB)
    • Left anterior hemiblock (LAH, LAHB).
    • Left posterior hemiblock (LPH, LPHB).
  • Right bundle branch block (RSB)

The following degrees of severity of intraventricular block can be differentiated:

  • Severity I – incomplete block
  • Severity II – intermittent block
  • Severity III – permanent (durable) block

Etiology (causes)

Biographical causes

  • Age of life – older age

Causes related to disease