Lown-Ganong-Levine Syndrome Workup

Updated: Jan 09, 2017
  • Author: Daniel M Beyerbach, MD, PhD; Chief Editor: Jeffrey N Rottman, MD  more...
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Workup

Laboratory Studies

Workup is directed at determining the cause of tachycardia. Lown-Ganong-Levine syndrome (LGL) is an outdated diagnosis, and as such no workup is directed at making this diagnosis. However, identification of a short PR interval during sinus rhythm in a patient with paroxysmal supraventricular tachycardia (PSVT) should raise suspicion of a possible underlying bypass tract (ie, Wolff-Parkinson-White syndrome [WPW]). In the case of isolated short PR interval with no history of tachycardia or symptoms suggestive of paroxysms of tachycardia, no further workup is indicated.

Patients may present in an acute episode of tachycardia or with a history of symptoms suggestive of paroxysms of tachycardia.

In the acute setting, institute a standard workup for tachycardia, including an ECG to document the rhythm, serum electrolytes, calcium, magnesium levels, and serum thyroid-stimulating hormone (TSH) levels.

For a history suggestive of recurrent paroxysms of tachycardia, a Holter monitor or event recorder may prove useful for documenting the rhythm during acute symptomatic episodes. Less commonly, particularly when paroxysms of tachycardia are more rare, an implantable loop recorder may prove helpful.

In the case of shortness of breath, posteroanterior and lateral chest films are indicated.

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Other Tests

To meet criteria for LGL, the 12-lead ECG taken during a period of normal sinus rhythm must demonstrate a PR interval less than or equal to 0.12 second and a normal QRS upstroke and duration, as in the image below.

ECG demonstrating a short PR interval of approxima ECG demonstrating a short PR interval of approximately 100 ms and normal QRS.

One of the most useful diagnostic tools is a 12-lead ECG recorded during a paroxysm of tachycardia. Such documentation satisfies the LGL criterion of tachycardia.

A delta wave on the QRS complex precludes the diagnosis of LGL, because one of the criteria for LGL is a normal QRS complex. A delta wave suggests the presence of an accessory pathway; occurrence of supraventricular tachycardia in the presence of an accessory pathway suggests WPW, another preexcitation syndrome, as in the image below.

Noninvasive mapping of cardiac arrhythmias is also possible with a 252-lead ECG and computed-tomography scan–based three-dimensional electroimaging. [28]

ECG demonstrating ventricular preexcitation. A del ECG demonstrating ventricular preexcitation. A delta wave, which corresponds to initial myocardial depolarization via a bypass tract, appears at the beginning of each QRS complex.

 

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Procedures

If tachycardia is present, diagnostic workup to determine the cause may include Valsalva maneuvers.

If the blood pressure is stable, the patient has no angina, is not presyncopal, and no carotid bruits are present, carotid massage may provide diagnostic information. Ideally, carotid massage should be performed during continuous 12-lead rhythm strip monitoring. The result of carotid massage may be termination of the tachycardia, or transient AV block that may provide a ventricular pause long enough to reveal an underlying atrial arrhythmia.

If these maneuvers fail to terminate the tachycardia, a trial of intravenous adenosine administration, again with simultaneous rhythm strip recording, may reveal the rhythm. Adenosine should not be administered if there is any indication of pre-excitation on the surface ECG.

In cases of recurrent tachycardia, an invasive electrophysiology study is warranted. This is particularly true when symptoms become intolerable, medical therapy is failing to prevent episodes of tachycardia, or when a ventricular arrhythmia is suspected.

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