Lown Ganong Levine Syndrome - Causes, Symptoms, Diagnosis, and Treatment

What Is Lown-Ganong-Levine Syndrome?

The Lown-Ganong-Levine (LGL) syndrome is one of the pre-excitation syndromes, with Wolff-Parkinson-White (WPW) syndrome being the most well-known. In WPW syndrome, an accessory conduction pathway known as the Bundle of Kent bypasses the atrioventricular (AV) node. No such pathway has been identified for LGL syndrome. Theories to explain LGL syndrome have suggested the presence of possible accessory fibers that bypass all or part of the AV node or a congenitally malfunctioning AV node in some cases. Regardless of the exact pathophysiology, conduction in LGL syndrome is transmitted from the atria to the bundle of His without the usual delay at the AV node.

The diagnostic criteria for Lown-Ganong-Levine (LGL) syndrome include a PR interval of no more than 120 ms, normal QRS complex duration, a normal or inverted P wave, and paroxysmal supraventricular tachycardia (PSVT), but not atrial fibrillation or flutter. This condition was first described in 1952, before the advent of electrophysiological testing, and some people question its existence as a distinct entity. If there is a short PR interval but no history of supraventricular tachycardia (SVT), it is likely just a normal variation. When arrhythmias in people meeting the diagnostic criteria have been investigated, another cause has often been found.

Sometimes, conduction through the AV node is abnormally fast, a condition known as enhanced atrioventricular nodal conduction (EAVNC). While tachycardia, along with increased stroke volume, helps meet the increased cardiac output demands during exercise, an excessively fast tachycardia can be inefficient and potentially harmful. The ventricles do not have enough time to fill during diastole, which may reduce cardiac output. Although tachycardia shortens both systole and diastole, diastole is shortened more significantly. Since around 75% of the blood flow to the right ventricle and 100 percent of the blood flow to the left ventricle occur during diastole, there is less time for myocardial perfusion precisely when the metabolic demand is higher.

What Is the Prevalence of Lown-Ganong-Levine Syndrome?

In Lown's initial retrospective study, nearly 200 out of 13,500 electrocardiograms (ECGs) showed a short PR interval and a normal QRS complex, indicating a prevalence of just over 1% in the selected population. Further investigation has revealed that the incidence of paroxysmal supraventricular tachycardia among individuals with Lown-Ganong-Levine syndrome is notably higher, approaching 11percent. However, in the general population, this syndrome is exceedingly rare, with a prevalence estimated to be less than one in a million.

What Are the Causes of Lown Ganong Levine Syndrome?

There is no definite cause established as of today for Lown Ganong Levine syndrome. The theory regarding the cause of this syndrome is stipulated as follows.

• Wolff-Parkinson-White or WPW is generally recognized as the cause for pre-excitation of the ventricles.

• Multiple underlying manifestations may result in the complete or partial bypass of the atrioventricular node.

What Are the Signs and Symptoms of Lown Ganong Levine Syndrome?

The Lown-Ganong-Levine syndrome has been reported in several age groups of patients and has not displayed any increase in the incidence in either the genders or ethnic races. Bernard Lown, William Ganong, and Samual Levine had an initial study that revealed approximately two hundred electrocardiograms of thirteen thousand evaluated patients displaying a short PR interval along with a normal QRS complex. Thus, the rate of prevalence of Lown Ganong Levine syndrome corresponds to merely 1 percent.

Mentioned below are a few signs and symptoms of Lown Ganong Levine syndrome.

• A history of paroxysmal atrial fibrillation.

• A history of atrial arrhythmias.

• Palpitations.

• The irregular rhythm of the heart.

• Increase in thyroid hormone.

• Abnormal electrolyte balance of the body.

• Increase or decrease in potassium levels.

• Increase or decrease in magnesium levels.

• The resting electrocardiogram displays a pattern of normal QRS complex but a short PR interval.

• Supraventricular tachycardia.

• Escalated stroke output.

• Reduced cardiac output.

How Can Lown Ganong Levine Syndrome Be Diagnosed?

There are several diagnostic tools for the diagnosis and confirmation of Lown Ganong Levine syndrome. Mentioned below are a few of them. It should be noted that a diagnosis to confirm the presence of Lown Ganong Levine syndrome only takes place after a thorough physical and medical examination but this syndrome has the tendency to not have any clinical manifestation at all. The classic sign of Lown Ganong Levine syndrome is a normal QRS complex with a short PR interval.

• Electrocardiogram.

• Electrophysiological study of the heart.

• Routine auscultation.

• Palpation of the arteries.

• Blood tests to determine thyroid levels.

• Blood picture of the electrolytes of the body, especially magnesium and potassium.

• Vagal maneuvers.

• Holter monitors.

• Implantable loop recorders.

• Absence of atrial fibrillation.

• Presence of paroxysmal supraventricular tachycardia.

• Absence of atrial flutter.

What Is the Treatment for Lown Ganong Levine Syndrome?

Treatment of Lown-Ganong-Levine is presently focused on the utilization of antiarrhythmic drugs. Mentioned below are the various treatment modalities and the management plan for Lown Ganong Levine syndrome.

• Radiofrequency catheter ablation.

• Prevention of tachyarrhythmias through the accessory pathway.

• Antiarrhythmic medications.

• Reducing the atrioventricular nodal conduction.

• Increasing the refractory period.

• Sodium channel blocking medications.

• Pacemaker implantation.

What Is the Prognosis of Lown Ganong Levine Syndrome?

The syndrome can lead to ventricular fibrillation or ventricular tachycardia and sudden death, although such occurrences are uncommon. Typically, the condition is much more benign and can be managed effectively with medications.

Conclusion

Lown Ganong Levine syndrome is a pattern of the heart that results in immature or early excitation of the heart's lower chambers, called ventricles. This condition is rare and thus is difficult to diagnose due to the limited information being established today. Lown-Ganong-Levine syndrome is mostly seen in women of young age as well as middle-aged women. Lown Ganong Levine syndrome leads to decreased cardiac output in the long run due to overuse of the ventricles. The condition has several diagnostic tests to be detected, and treatment depends on the severity as well as the clinical manifestations that the patient presents themselves with. Lown Ganong Levine syndrome is treatable, and the patient needs to follow the advice and suggestions of the healthcare provider. Reaching out to the healthcare provider may be beneficial.