Lown-Ganong-Levine syndrome: Difference between revisions

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* Lown-Ganong-Levine pattern may occur include Brechenmacher fibers or intranodal bypass tracts and James Fibers. Brenchmacher fibers account for 0.03% of the patients presenting with LGL.
* Lown-Ganong-Levine pattern may occur include Brechenmacher fibers or intranodal bypass tracts and James Fibers. Brenchmacher fibers account for 0.03% of the patients presenting with LGL.
*The intra-nodal bypass tracts allow the conduction of rapid action potential through AV-node bypassing the other slow pathways.  
*The intra-nodal bypass tracts allow the conduction of rapid action potential through AV-node bypassing the other slow pathways.  
==Clinical Features==
The clinical features of LGL overlap with other [[pre-excitation syndrome|pre-excitation syndromes]]. The patient can present with following features. <ref name="LOWN GANONG LEVINE 1952 pp. 693–706">{{cite journal | last=LOWN | first=BERNARD | last2=GANONG | first2=WILLIAM F. | last3=LEVINE | first3=SAMUEL A. | title=The Syndrome of Short P-R Interval Normal QRS Complex and Paroxysmal Rapid Heart Action | journal=Circulation | publisher=Ovid Technologies (Wolters Kluwer Health) | volume=5 | issue=5 | year=1952 | issn=0009-7322 | pmid=14926053 | doi=10.1161/01.cir.5.5.693 | pages=693–706}}</ref>
*[[Palpitations]]
*[[Lightheadedness]]
*[[Shortness of breath]]
*[[Syncope]]
* In case of an underlying cardiac structural defect, it can also present with [[chest pain]] or episodes of [[tachycardia]].


==Differentiating LGL from other Diseases==
==Differentiating LGL from other Diseases==

Revision as of 16:59, 20 August 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Usman Ali Akbar, M.B.B.S.[2]

Synonyms and keywords: Lown-Ganong-Levine Syndrome, LGL syndrome,Pre-excitation syndromes,Short PR Normal QRS Complex Syndrome

Overview

Lown-Ganong-Levine Syndrome (LGL) is one of the pre-excitation syndromes that present with EKG findings of short PR interval, narrow/normal QRS complex, and normal P wave. The presence of accessory bundles fibers such as James fiber leads to the development of abnormal conduction pathways. The LGL pattern was described in 1952 by Bernard Lown, William Francis Ganong, and Samual Levine. Patients present with a history of palpitations, lightheadedness, shortness of breath, and sometimes chest pain. There is an increased risk of tachyarrhythmias and syncope. EKG is the principal modality of investigation for establishing a diagnosis. Usually, antiarrhythmics are given to prevent the development of tachyarrhythmias but recently radiofrequency ablation of the accessory pathway has been the main stray of treatment with a good prognosis.

Historical Perspective

Following is timeline of of LGL syndrome with its discovery and developments of its bypass tracts.[1][2][3]

Historical timeline of LGL Syndrome
Year Description
1938 Clerc, Levy and Critesco in 1938 first reported cases in which there was occurence of frequent paroxysms of tachycardia. The EKG of such patients consist of a short PR interval and normal QRS interval
1946 Burch and Kimball hinted on existence of the atrio-Hisian pathway
1952 The Lown-Ganong-Levine (LGL) pattern was described in 1952 by Bernard Lown, William Francis Ganong, and Samual Levine.
1961,1974 In 1961 and subsequently in 1974 anatomic pathway was identified and reported by James and Brechemacher respectively.

Classification

  • LGL syndrome can be classified based on the accessory pathways into the following categories.[1][2]
Accessory Pathway Description
James Fibers They can be present as a normal part of AV node but these fibers have been established as an anatomic reason for LGL syndrome
Brechmacher fibers These atrio-Hisian tracts are reported to have a frequency of 0.03 % and can be theoratically a cause of LGL syndrome
Intra-nodal bypass tracts Intra-nodal bypass tracts would allow the conduction of rapid action potential through AV node bypassing the other slow pathways.

Pathophysiology

  • The pathophysiology of LGL syndrome has not yet been completely understood.
  • Multiple theories have been proposed to suggest the mechanism of LGL. [1]
  • The current theory supporting the mechanism of LGL is that it may result from numerous underlying causes that involve junctional pathways that partially or wholly bypass the AV node with subsequent normal conduction down the bundle of His.
  • The three accessory pathways as discussed in classification has been proposed to be the main triggering factors for the development of LGL.
  • Lown-Ganong-Levine pattern may occur include Brechenmacher fibers or intranodal bypass tracts and James Fibers. Brenchmacher fibers account for 0.03% of the patients presenting with LGL.
  • The intra-nodal bypass tracts allow the conduction of rapid action potential through AV-node bypassing the other slow pathways.

Differentiating LGL from other Diseases

The differential diagnosis for Lown-Ganong-Levine includes

Epidemiology and Demographics

  • The Lown-Ganong-Levine pattern does not show an increased incidence in one particular sex or ethnic background.
  • In a retrospective study conducted by Bernard Lown, William Francis Ganong, and Samual Levine 200 electrocardiograms (EKG) of 13500 patients showed EKG findings with the prevalence of just over 1%. [1]

Age

  • There is currently insufficient data regarding age predilection of LGL syndrome.

Gender

  • There is currently insufficient data regarding gender predilection of LGL syndrome. However, Lown in 1952 reported 70.9% of the 34 cases in women.[1]

Race

  • There is currently insufficient data regarding race predilection of LGL syndrome.

Risk Factors

The data regarding the risk factors predisposing to LGL syndrome is insufficient. However, the following conditions or factors may lead to various pre-excitation syndromes.

  • Presence of accessory bypass tracts
  • High risk population for sudden cardiac death in Pre-excitation syndromes include
    • Policemen
    • Athletes
    • Firemen
    • Pilots
    • Steelworkers

Natural History, Complications and Prognosis

Natural History

Complications

  • Certain medications such as sympathomimetics should be used with caution in the patients of LGL syndrome. Digitalis does not have any effect in LGL syndrome but it can slow conduction via the AV-node. This can prevent AVRT in these patients.
  • Beta-blockers do not affect the accessory pathway directly but can slow conduction through the AV node similar to digitalis.

Prognosis

There is an overall good prognosis in patients with LGL syndrome. Patients are usually asymptomatic but some can develop certain clinical features such as palpitations, shortness of breath, and occasional episodes of atrial fibrillation, atrial flutter, AVRT, and other tachyarrhythmias. They can also lead to the development of ventricular arrhythmias in rare cases.[1][4]

Diagnosis

Diagnostic Criteria

Characteristic ECG findings of LGL syndrome are [1]

Symptoms

  • LGL syndrome is usually asymptomatic.
  • Symptoms of LGL syndrome may include the following:

Physical Examination

  • Patients with LGL syndrome usually appear normal.
  • Physical examination findings are limited in LGL syndrome.
  • During cardiac auscultation or palpation of peripheral pulses, there can be irregular rhythm.

Laboratory Findings

  • There are no specific laboratory findings associated with LGL syndrome.

Imaging Findings

ECG

The diagnosis of LGL syndrome can be made by the use of resting EKG. EKG finding usually shows

  • Short PR interval (<120ms)
  • Normal P wave axis
  • Normal/narrow QRS morphology in the presence of paroxysmal tachyarrhythmia.
ECG showing LGL syndrome with short PR interval, narrow QRS complex and normal P waves Source: LITFL https://litfl.com/lown-ganong-levine-syndrome/


Other Diagnostic Studies

  • Holter monitors or implantable loop recorders may provide insight to the underlying conductions abnormalities.

Treatment

Medical Therapy

Surgery

Patients refractory to medical management can be managed by the use of radiofrequency catheter ablation as it has become primary treatment in various pre-excitation syndromes. This can be further implicated by the implantation of a permanent pacemaker.

Prevention

  • There are no primary preventive measures available for LGL syndrome.

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 LOWN, BERNARD; GANONG, WILLIAM F.; LEVINE, SAMUEL A. (1952). "The Syndrome of Short P-R Interval Normal QRS Complex and Paroxysmal Rapid Heart Action". Circulation. Ovid Technologies (Wolters Kluwer Health). 5 (5): 693–706. doi:10.1161/01.cir.5.5.693. ISSN 0009-7322. PMID 14926053.
  2. 2.0 2.1 Manning, G W (1978). "Lown-Ganong-Levine syndrome". Circulation. Ovid Technologies (Wolters Kluwer Health). 58 (3): 576–577. doi:10.1161/01.cir.58.3.576. ISSN 0009-7322. PMID 679452.
  3. DOUGLAS, JOHN E. (1972). "Lown-Ganong-Levine Syndrome". Circulation. Ovid Technologies (Wolters Kluwer Health). 45 (5): 1143–1144. doi:10.1161/01.cir.45.5.1143. ISSN 0009-7322. PMID 5020803.
  4. Benditt, D G; Pritchett, L C; Smith, W M; Wallace, A G; Gallagher, J J (1978). "Characteristics of atrioventricular conduction and the spectrum of arrhythmias in lown-ganong-levine syndrome". Circulation. Ovid Technologies (Wolters Kluwer Health). 57 (3): 454–465. doi:10.1161/01.cir.57.3.454. ISSN 0009-7322. PMID 624155.
  5. Benditt, D G; Klein, G J; Kriett, J M; Dunnigan, A; Benson, D W (1984). "Enhanced atrioventricular nodal conduction in man: electrophysiologic effects of pharmacologic autonomic blockade". Circulation. Ovid Technologies (Wolters Kluwer Health). 69 (6): 1088–1095. doi:10.1161/01.cir.69.6.1088. ISSN 0009-7322. PMID 6713613.
  6. Caracta, Anthony R.; Damato, Anthony N.; Gallagher, John J.; Josephson, Mark E.; Varghese, P.Jacob; Lau, Sun H.; Westura, Edwin E. (1973). "Electrophysiologic studies in the syndrome of short P-R interval, normal QRS complex". The American Journal of Cardiology. Elsevier BV. 31 (2): 245–253. doi:10.1016/0002-9149(73)91037-0. ISSN 0002-9149.

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