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Bundle of His

named after the Swiss anatomist Wilhelm His (1831-1904)
Synonym: fasciculus atrioventricularis
German: His-Bündel

1 Definition

The bundle of His is a component of the heart's conduction system. It is located about 1 cm distally from the AV node, in the direction of the apex.

2 Physiology

Normal excitement begins at sinus node, the primary pacemaker, with a frequency of about 60 to 80 impulses per minute. From there the excitation is passed through the right atrium into the atrioventricular node (AV node), which in case of failure of the sinus node or an AV block, i.e. a disturbed reconciliation from the sinus node to the AV node, a secondary pacemaker can step in with a frequency of 40 to 50 impulses per minute.

From the AV node a forwarding of stimulation to the His bundle now takes place. It begins with a common trunk, the truncus fasciculi atrioventricularis, which is then divided after a few millimetres into three branches, which are called the bundle branch (two left and one right). The bundle branch divides further at the apex further into the purkinje fibres, which form the final part of the conduction system and are in contact with the myocardial cells.

3 Pathophysiology

The His bundle can, in the event of incapacitation of the sinus and AV node also forms an intrinsic rhythm, which is 20 to 30 excitations per minute and called ventricular rhythm. However, long-term survival with this ventricular rhythm is usually not possible, so in these patients, if possible, a cardiac pacemaker is used before the first two pacemakers fail completely.

Other disturbances in the area of the His bundle include the so-called bundle branch block and the much less common congenital His bundle tachycardia or junctional ectopic tachycardia which may occur in neonates and infants aged up to 6 months.

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