The syndrome of Wolff-Parkinson-White (WPW) is classically defined by an electrocardiogram with a short PR interval, a prolonged QRS complex that begins with an abnormal initial force known as the delta wave, and is seen in patients who are predisposed to tachyarrhythmias.1 Figure 1 shows the ECG of WPW compared with a normal ECG. The PR interval is short because the QRS (the delta wave) begins abnormally early in relationship to the end of the P wave. Thus, the PR interval is shortened to the same extent that the QRS is prolonged. The diagram on the right depicts atrial activation in phase 1. Phase 2 demonstrates premature ventricular excitation (preexcitation) over an accessory atrioventricular connection that conducts without the delay exhibited by the atrioventricular node. The anomalous, premature depolarization is indicated by the darker grain pattern in the heart and in the ECG. During phase 3, the ventricle is
John P. Boineau, E. Neil Moore, Will C. Sealy, Jackie H. Kasell. Epicardial Mapping in Wolff-Parkinson-White Syndrome. Arch Intern Med. 1975;135(3):422–431. doi:10.1001/archinte.1975.00330030072008
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