Lown-Ganong-Levine syndrome Microchapters
Synonyms and keywords: Lown-Ganong-Levine Syndrome, LGL syndrome, Pre-excitation syndromes, Short PR Normal QRS Complex Syndrome, Clerc-Lévy-Cristesco syndrome, Coronary nodal rhythm syndrome, Short PQ interval syndrome, Short P-R syndrome.
Lown-Ganong-Levine syndrome (LGL) is actually a pre-excitation syndrome with EKG findings including short PR interval, narrow or normal QRS complex, and a normal P wave. It is caused by the presence of accessory bundles of fibers known as James fibers which lead to the development of abnormal conduction pathways. The LGL syndrome was named after Bernard Lown, William Francis Ganong, and Samual Levine who described it in 1952. Patients of LGL usually 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 pathways has been the mainstay of treatment with a good prognosis.
- Following is the timeline of LGL syndrome with its discovery and developments of its bypass tracts:
|Intra-nodal bypass tracts|
- The pathophysiology of LGL syndrome is not yet understood completely.
- Multiple theories have been proposed to suggest the mechanism of LGL.
- The current theory supporting the mechanism of LGL is that it may result from numerous underlying causes that involve junctional pathways which partially or wholly bypass the AV node with subsequent normal conduction down the bundle of His.
- The three accessory pathways as discussed in the classification section have been proposed to be the main triggering factors for the development of LGL.
- Lown-Ganong-Levine pattern may occur including the following fibers:
- The intra-nodal bypass tracts allow the rapid conduction of action potential through the AV node bypassing the other slow pathways.
- The exact causes of LGL syndrome have not been completely understood yet.
- However, the presence of following accessory pathways can predispose a patient to the development of LGL syndrome:
- Sometimes, patients with LGL syndrome have a history of congenital heart disease.
Differentiating Lown-Ganong-Levine Syndrome from other Diseases
- The differential diagnosis for Lown-Ganong-Levine syndrome includes the following diseases as shown in the table below:
Epidemiology and Demographics
- In a retrospective study conducted by Bernard Lown, William Francis Ganong, and Samual Levine, 200 electrocardiograms (EKGs) of 13500 patients showed EKG findings with the prevalence of just over 1%.
- There is currently insufficient data regarding gender predilection of LGL syndrome as the LGL pattern is not associated with an increased incidence in one particular sex.
- However, Lown in 1952 reported 70.9% of the 34 cases in women.
- There is currently insufficient data regarding race predilection of LGL syndrome as the LGL pattern is not associated with an increased incidence in one particular ethnic background.
- The data regarding the risk factors predisposing to LGL syndrome is insufficient. However, the following conditions or factors may lead to the various pre-excitation syndromes:
Natural History, Complications and Prognosis
- LGL syndrome can be asymptomatic or can present with the following symptoms:
- In the case of congenital heart disease or genetic anomaly, it can also present as paroxysms of tachycardia or chest pain.
- There is an increased risk of developing tachyarrhythmias.
- Certain medications such as sympathomimetics should be used with caution in patients of LGL syndrome.
- Digitalis does not produce any effect on LGL syndrome but it can slow down the conduction in the AV node which prevents AVRT in these patients.
- Although beta-blockers do not directly affect the accessory pathway, however, they can slow conduction through the AV node similar to digitalis.
- The overall prognosis of patients with LGL syndrome is good.
- Patients are usually asymptomatic but some can develop certain clinical features such as:
- Characteristic ECG findings of LGL syndrome are 
History and Symptoms
- LGL syndrome is usually asymptomatic.
- The symptoms of LGL syndrome usually overlap with those of pre-excitation syndrome and may include the following:
- 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.
- The diagnosis of LGL syndrome can be made by the use of resting EKG. EKG findings usually show:
Other Diagnostic Studies
- Holter monitors or implantable loop recorders may provide insight into the underlying conduction abnormalities.
- The mainstay of therapy for LGL syndrome is the use of antiarrhythmic medications to prevent tachyarrhythmias.
- Medications such as digitalis, beta-blockers, calcium channel blockers and Class I and III antiarrhythmic drugs have been used to slow down AV conduction and prevent AVRT and other arrhythmias.
- Drugs such as sotalol and amiodarone have promising effects as a treatment option for LGL syndrome but are still under investigation and need further studies.
- Patients refractory to medical management can be managed by the use of radiofrequency catheter ablation as it has become a primary treatment option in various pre-excitation syndromes.
- This can be further implicated by the implantation of a permanent pacemaker.
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