Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Historical Perspective
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 following categories
| Accessory Pathway
|
Description
|
| James Fibers
|
They can be present as normal part of AV node but these fibers have been established as 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.
- 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.
Clinical Features
Differentiating [disease name] from other Diseases
- [Disease name] must be differentiated from other diseases that cause [clinical feature 1], [clinical feature 2], and [clinical feature 3], such as:
- [Differential dx1]
- [Differential dx2]
- [Differential dx3]
Epidemiology and Demographics
- The prevalence of [disease name] is approximately [number or range] per 100,000 individuals worldwide.
- In [year], the incidence of [disease name] was estimated to be [number or range] cases per 100,000 individuals in [location].
Age
- Patients of all age groups may develop [disease name].
- [Disease name] is more commonly observed among patients aged [age range] years old.
- [Disease name] is more commonly observed among [elderly patients/young patients/children].
Gender
- [Disease name] affects men and women equally.
- [Gender 1] are more commonly affected with [disease name] than [gender 2].
- The [gender 1] to [Gender 2] ratio is approximately [number > 1] to 1.
Race
- There is no racial predilection for [disease name].
- [Disease name] usually affects individuals of the [race 1] race.
- [Race 2] individuals are less likely to develop [disease name].
Risk Factors
- Common risk factors in the development of [disease name] are [risk factor 1], [risk factor 2], [risk factor 3], and [risk factor 4].
Natural History, Complications and Prognosis
- The majority of patients with [disease name] remain asymptomatic for [duration/years].
- Early clinical features include [manifestation 1], [manifestation 2], and [manifestation 3].
- If left untreated, [#%] of patients with [disease name] may progress to develop [manifestation 1], [manifestation 2], and [manifestation 3].
- Common complications of [disease name] include [complication 1], [complication 2], and [complication 3].
- Prognosis is generally [excellent/good/poor], and the [1/5/10year mortality/survival rate] of patients with [disease name] is approximately [#%].
Diagnosis
Diagnostic Criteria
- The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met:
- [criterion 1]
- [criterion 2]
- [criterion 3]
- [criterion 4]
Symptoms
- [Disease name] is usually asymptomatic.
- Symptoms of [disease name] may include the following:
- [symptom 1]
- [symptom 2]
- [symptom 3]
- [symptom 4]
- [symptom 5]
- [symptom 6]
Physical Examination
- Patients with [disease name] usually appear [general appearance].
- Physical examination may be remarkable for:
- [finding 1]
- [finding 2]
- [finding 3]
- [finding 4]
- [finding 5]
- [finding 6]
Laboratory Findings
- There are no specific laboratory findings associated with [disease name].
- A [positive/negative] [test name] is diagnostic of [disease name].
- An [elevated/reduced] concentration of [serum/blood/urinary/CSF/other] [lab test] is diagnostic of [disease name].
- Other laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].
Imaging Findings
- There are no [imaging study] findings associated with [disease name].
- [Imaging study 1] is the imaging modality of choice for [disease name].
- On [imaging study 1], [disease name] is characterized by [finding 1], [finding 2], and [finding 3].
- [Imaging study 2] may demonstrate [finding 1], [finding 2], and [finding 3].
Other Diagnostic Studies
- [Disease name] may also be diagnosed using [diagnostic study name].
- Findings on [diagnostic study name] include [finding 1], [finding 2], and [finding 3].
Treatment
Medical Therapy
- There is no treatment for [disease name]; the mainstay of therapy is supportive care.
- The mainstay of therapy for [disease name] is [medical therapy 1] and [medical therapy 2].
- [Medical therapy 1] acts by [mechanism of action 1].
- Response to [medical therapy 1] can be monitored with [test/physical finding/imaging] every [frequency/duration].
Surgery
- Surgery is the mainstay of therapy for [disease name].
- [Surgical procedure] in conjunction with [chemotherapy/radiation] is the most common approach to the treatment of [disease name].
- [Surgical procedure] can only be performed for patients with [disease stage] [disease name].
Prevention
- There are no primary preventive measures available for [disease name].
- Effective measures for the primary prevention of [disease name] include [measure1], [measure2], and [measure3].
- Once diagnosed and successfully treated, patients with [disease name] are followed-up every [duration]. Follow-up testing includes [test 1], [test 2], and [test 3].
References
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