Glossary

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W

Wenckebach operation (upper rate behavior). In Medtronic DDD pacemakers, an operation which limits the average ventricular pacing rate to one less than the programmed upper rate when the intrinsic atrial rates rise above this upper rate. The EGG displays this operation as a gradual prolonging of the pacemaker’s A-V interval until one of the P-waves falls into the atrial refractory period and is not sensed. Since no A-V interval is started by this last P­wave, there will be no ventricular output synchronized to this atrial event.

Wolff-Parkinson-White syndrome. A common type of pre-excitation syndrome, an abnormal condition in which impulses enter the ventricles from the atria through an accessory pathway that bypasses the AV junction. This results in a short PR interval, a wide QRS complex with an initial slurring (delta wave) and a tendency to paroxysmal supraventricular tachycardia. Abbreviated WPW syndrome.