Lown-Ganong-Levine syndrome

Lown-Ganong-Levine syndrome (LGL syndrome, short PQ syndrome, Clerc-Levy-Christesco syndrome, CLC syndrome) is a syndrome of pre-exitation of the valves. It is a heart arrhythmia, in which the depolarisation wave spreads trough the acessory James branch (bundle of James). Bundle of James connects the myocardium of the valves with the bundle Hiss (atrio-Hisian pathway). The wave of depolarisation bypasses the AV node which leads to the shortening of the PQ interval and premature activation of the valve myocardium (there is no delay of the potential in the AV node).

Etiologiy
The disease is mostly congenital. It can be also caused by an endocarditis or a myoocarditis.

A very rare or a familial form of the LGL syndrome also exists.

Symptoms
During the paroxysm of a supra-ventricular tachycardia a patient might list following symptoms:
 * palpitations (feelings of a heartbeat);
 * feeling of a "short breath", the need to "finish a breath".

Diagnostics
The diagnostics leans on a ECG scan. It is mostly an asymptomatic patient that has an ECG for a different indication (e.g. preop examination). In ECG we can see:
 * shortening of the PQ interval→ PQ ≤ 0,12 s (the depolarisation wave bypasses the AV node);
 * normal QRS complex, no delta wave (Bundle of James connects the valves with the bundle of Hiss, the valves are therefore exited the natural way).

To get a LGL syndrome diagnosis a symptomatic tachycardia must be added to the mentioned changes.

Pro stanovení diagnózy LGL syndromu musí k výše uvedeným změnám na EKG přibýt i symptomatická tachykardie Shortened PQ interval with normal QRS complex without the tachycardia is called an "accelerated AV pass"

The most common tachycardia associated with the LGL syndrom is a supra-ventricular tachycardia, which originates by reentry mechanism (AVRT, atrioventricular reentry tachycardia; AVNRT, atriovventricular nnode reentry tachycaria)

AV node leads the wave of depolarisation very slowly, which makes the desirable delay of the potential from the atriums to the valves (first the atrium contraction must finish, then the valve one). The AV node also works as a "physiological filter" - it works on the "all or nothing" principle, it does not let trough an insufficient potential. That is why e.g. during atrial fibrillation not every depolarisation wave gets to the valves. The accessory branch (bypassing the AV node) does not have this ability and if the frequency during a atrial fibrillation is a 250/min, all 250 potentials are transferred onto the valves which leads to ventricular fibrillation and potentially even a sudden death

Complications
Listed LGL syndrome complications:
 * 1) atrial fibrillation;
 * 2) ventricular tachycardia;
 * 3) ventricular fibrillation;
 * 4) sudden death.

Treatment
The therapeutic effort is directed towards an etiological treatment of the tachycardia (mostly its treatment of the paroxysmal supra-ventricular tachycardia). Basically it may be a
 * pharmacological (antiarrhythmics) treatment or
 * non-pharmacological (radifrequential ablation of the accessory bunch)

Literature

 * BEYERBACH, Daniel M a Christopher CADMAN. Lown-Ganong-Levine Syndrome [online]. [cit. 2010-12-17]. .


 * GANONG, William F. Přehled lékařské fyziologie. 20. vydání. Galén, 2005. 890 s. ISBN 80-7262-311-7.


 * HAMAN, Petr. Výukový web EKG : Základy EKG [online]. [cit. 2010-11-01]. .


 * HOLAJ, Robert. Kardiologický kroužek. III. interní klinika VFN a 1. LF UK v Praze, 2009.
 * VILIKUS, Zdeněk. Interpretace EKG v klidu a při zátěži. Ústav tělovýchovného lékařství 1. LF UK a VFN; 2010.

Source

 * ws:Lownův-Ganongův-Levineův syndrom