• Lown-Ganong-Levine (LGL) syndrome is an inherited disorder in which there is an extension of the anterior internodal tract (Bundle of James) that serves as an accessory pathway allowing impulse propagation from the atria to His bundle bypassing AV node.
• On ECG, there is shortened PR interval because AV is bypassed.
• There is no delta wave and QRS is as not widened as in Wolff-Parkinson White syndrome because impulses don't go directly to the ventricles but rather travel down the normal His-Purkinje system.
• Occasionally, an irritable impulse from rapid-pacing atrial or junctional foci (e.g. SVT) can propagate to the ventricles via the accessory pathway that can degenerate into ventricular arrhythmias.
