The LGL syndrome (Lown-Ganong-Levine Syndrome) is one of the cardiac arrhythmias. It is more precisely a preexcitation syndrome. This means that the ventricles are excited a little too early, whereupon they contract and pump blood into the body. This process leads to unpleasant palpitations with a significantly increased pulse rate. However, there are hardly any symptoms.
Causes of the LGL syndrome
There are various theories, but none of them have been proven yet. The exact mechanism that leads to the seizure-like tachycardia is not yet understood. The discoverers of the disease have assumed that accessory pathways are the cause.
However, this theory is very controversial today. Accessory pathways are additional pathways that transmit the excitation of the heart too quickly. This can alter the normal excitation process of the heart, as the heart chambers are excited too early. This then leads to tachycardia (a too fast heartbeat). In LGL syndrome, accessory pathways have not been proven to be the cause.
Diagnosis
As with any diagnosis, the first step is a conversation with the doctor and a physical examination in which the heart is listened to. The heart’s excitation process is imaged with the help of an ECG (echocardiography). It is the method of choice for detecting cardiac arrhythmias.
Since the tachycardia typical of the LGL syndrome only occurs in phases, a long-term ECG examination is performed to be able to depict such an event. Other changes in the heart must have been excluded by means of the ECG and the heart ultrasound in order to be able to make a diagnosis of LGL syndrome. The ECG shows the tachycardia typical of the disease, with an increased heart rate (a rapid pulse).
Furthermore, the so-called PQ time is shortened. It is less than 0.12 seconds. The PQ time describes the transfer time at the heart.
This means that during this time the atria of the heart are already excited, while the ventricles have yet to be excited. The PQ time must be 0.12 seconds or less, otherwise it is by definition not an LGL syndrome. The rest of the ECG must look normal, especially the so-called ventricular complex, which reflects the excitation sequence of the ventricles, is configured normally. If this is not the case and a so-called delta wave is present, it is Wolf-Parkinson-White syndrome. This can lead to life-threatening ventricular fibrillation.
