Wolff–Parkinson–White syndrome

Wolff–Parkinson–White syndrome is a heart rhythm disorder in which an extra electrical pathway connects the atria and ventricles. The pathway can trigger episodes of rapid heartbeat.

Accessory pathway: An abnormal electrical connection between the heart’s atria and ventricles that bypasses the atrioventricular node. This extra connection is the defining anatomical feature of the syndrome.
Delta wave: A slurred initial upstroke of the QRS complex on an electrocardiogram, caused by early ventricular activation. It is a characteristic surface sign of ventricular pre-excitation in this syndrome.
Cardiac conduction system: The network of specialized cells that generates and carries electrical impulses through the heart. The syndrome is an abnormal route within the heart’s electrical conduction system.
Atrioventricular nodal reentrant tachycardia: A common rapid rhythm caused by a reentrant circuit within or near the atrioventricular node. It can resemble pathway-mediated tachycardia but does not require an accessory atrioventricular connection.
Atrioventricular reentrant tachycardia: A rapid heart rhythm maintained by an electrical impulse circulating through a reentrant pathway involving the atria and ventricles. The accessory pathway can form one limb of this recurring electrical circuit.
Electrophysiology study: An invasive test that maps the heart’s electrical conduction using catheters placed inside the heart. It can locate the accessory pathway and assess its conduction properties.
Sinoatrial node: A group of specialized cells in the right atrium that normally initiates each heartbeat. Its impulses can reach the ventricles by both the normal route and the accessory pathway.
Long QT syndrome: An inherited or acquired disorder of cardiac repolarization that prolongs the QT interval and can cause dangerous arrhythmias. It is another electrical heart disorder, but its abnormality concerns repolarization rather than an extra conduction route.
Atrioventricular node: A cluster of specialized heart cells that delays electrical impulses traveling from the atria to the ventricles. The abnormal pathway bypasses this normal electrical gate.
Catheter ablation: A procedure that destroys a small area of tissue responsible for an abnormal heart rhythm using energy delivered through a catheter. Ablation can eliminate the accessory pathway and prevent recurrent episodes.

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