A Glimpse into the Rare Find of Lown-Ganong-Levine Syndrome

Background

Lown-Ganong-Levine (LGL) syndrome is a paroxysmal supraventricular tachycardia (SVT) that is rarely seen and considered somewhat mysterious. The SVT is considered to be slightly similar to Wolff-Parkinson-White (WPW) syndrome due to the short PR (<120 ms), indicating pre-excitation; however, that is where the similarities end. In fact, there is not enough evidence to truly define an anatomical structure abnormality or the presence of a bypass tract.¹ LGL was discovered in 1952 by Bernard Lown, William Ganong, and Samuel Albert Levine. The founders had difficulty providing a sound definition for the SVT, and to this day, the diagnosis is not simple to come to understand.

Presentation and Diagnosis

Patients with LGL report long histories of palpitations, which begin in early adulthood and become less frequent with age. Often the palpitations are accompanied by angina pectoris, dizziness, lightheadedness, and shortness of breath.² In addition, short, self-terminating bursts of atrial fibrillation have been noted.³ The average age of onset is 33.5 years; and females account for 70.9% of cases.¹ The mortality rate is low; however, some cases have resulted in ventricular fibrillation and sudden cardiac death.² Diagnosis is made on 12-lead EKG with observation of the following attributes: normal or inverted PR wave, short PR interval, absence of a delta wave, and normal QRS complex morphology and duration.³ Dr. Gurvinder Rull noted that the duration of conduction through the AV node is fast, revealing enhanced atrioventricular nodal conduction (EAVNC).²

Treatment

According to Rull, ablation is not performed because there is no aberrant bundle to ablate as in WPW. Beta blockers are utilized to slow AV nodal conduction. Non-dihydropyridine calcium channel blockers are used to treat acute episodes of paroxysmal supraventricular tachycardia; however, verapamil should not be used in conjunction with beta blockers, as this combination may cause complete heart block.² Permanent pacemaker implantation is a last resort for management.²

Case Study

Our patient is a 22-year-old white female with no prior significant medical history, and taking no home medications. Before referral to an electrophysiologist, she presented to the local Emergency Department (ED) on several occasions for symptoms of palpitations. She also described feeling atypical chest pain, shortness of breath, and lightheadedness. EKG in the ED revealed a short PR interval. Outpatient echocardiogram and stress testing revealed normal ejection fraction (65%), normal valvular function, and no coronary artery disease. CBC, BMP, and PT/INR were all within normal limits. According to the patient, there was no contributing family history to report.

EP Study and Findings

At baseline, the patient was found to be in a low atrial rhythm with a cycle length of 750 msec, PR interval of 70 msec, QRS interval of 82 msec, QT interval of 358 msec, AH interval of 50 msec, and HV interval of 47 msec. VA conduction was present and VA Wenckebach cycle length was 420 msec; conduction was concentric and decremental. The AV Wenckebach at baseline was 320 msec; it was 210 msec following an isuprel infusion. Program electrostimulation with up to 3 extrastimuli was not successful in ventricular arrhythmia induction. Several attempts at induction of SVT did not result in any tachyarrhythmia. The patient had a short run of atrial fibrillation, which did not manifest any evidence of anterograde conduction through an accessory pathway, and was self terminating. The patient did convert to a normal sinus rhythm, during which her PR interval was 142 msec, with a cycle length of 670 msec. It was determined that the patient has EAVNC, which might be a type of LGL syndrome. No ablation was performed..

Follow-Up

After a long discussion with the patient and her family, they agreed that there was no indication for radiofrequency ablation. Although disappointed by the inability to ablate the tachycardia, the decision was made to begin a home medication regimen to help with prevention and breakthrough. Propranolol 10 mg by mouth daily was prescribed for initial treatment. The first follow-up appointment one-month post EPS reported no new events of tachycardia or associated symptomology. 

Summary

Clearly, LGL syndrome is evasive and mysterious at best. This form of SVT, while rarely seen in the EP lab, is somewhat easily diagnosed and surely treatable. Luckily, the mortality rate is statistically low, and patients tend respond quickly to medical therapy.² Our staff members were excited to be introduced to an unusual and unfamiliar tachycardia — resulting in learning and acquiring new EP knowledge for all involved in the case. ■

References

1. Beyerbach D, Cadman C. Lown-Ganong-Levine Syndrome. Medscape. Published September 15, 2014. Available online at https://emedicine.medscape.com/article/160097-overview. Accessed January 13, 2015.
2. Rull G. Lown-Ganong-Levine Syndrome. EMIS. Published March 2, 2014. Available online at www.patient.co.uk/print/983. Accessed January 13, 2015.
3. Sharma MK, Misra S. Anaesthetic management of a patient with Lown-Ganong-Levine syndrome – a case report. Med J Armed Forces India. 2011;67(3):285-287.

Disclosures: The authors have no conflicts of interest to report regarding the content herein.