Wolff-Parkinson-White syndrom

On an ECG tracing, a delta wave is usually an unexpected finding. In the QRS complex, the Delta wave takes the place of the Q wave. In the graphic below you can see the difference between the tracing from normal sinus rhythm and a heartbeat tracing that includes a Delta wave. You may also notice that the PR segment (the portion of the tracing along the baseline, between the depolarization of the atria (P wave) and the beginning of the depolarization of the ventricles (QRS complex)) is missing. This happens because the electrical signal from the atria is being conducted to the ventricles immediately after atrial contraction, carried along an anomalous accessory pathway called the Bundle of Kent instead of through the AV node, which delays signal conduction to allow the ventricles to fill with blood before contraction. This produces Wolff Parkinson White (WPW) syndrome, which may be asymptomatic for a person’s entire life, but it also has the potential for initiating dangerous, rapi

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http://spermup.blogspot.com/ The Wolff-Parkinson-White syndrome PSVT due to accessory pathways (the Wolff-Parkinson-White syndrome, WPW) This syndrome is the second most common cause of PSVT. The mechanism of the tachyarrhythmia relates to the presence of two pathways between the atria and the ventricles that have different conducting properties (see figure1). Figure 1 click for big picture Usually the period of these pathways during which they can not respond to stimulus to conduct (refractory period) exceeds that of the normal AV nodal-His pathway. Thus, a premature atrial impulse may block at the accessory pathway and conduct antegrade down the normal pathway and enter the accessory one in a retrograde direction and reentering the atrium to cause a circus movement tachycardia (orthodromic, see figure 3). Figure 3 click for big picture Figure 3a click for big picture Since the accessory pathway provides retroconduction to the atria, P waves (if seen) are usually inverted in EKG