基础回顾与心律失常.ppt

* Wolff-Parkinson-White syndrome Extra-nodal AV conduction pathways Atrioventricular bypass tracts, or accessory pathways, can be found anywhere along the muscular portion of the posterior and lateral aspects of the mitral and tricuspid annuli. They can be classified by their anatomic location as either ? right-sided, ? left-sided, ? posteroseptal, or ? anteroseptal. Patients with Wolff-Parkinson-White syndrome have an accessory pathway that can conduct in both an anterograde or retrograde direction. As we will see on the next page, anterograde conduction via the accessory pathway during sinus rhythm bypasses the AV node, pre-exciting the ventricle and producing the characteristic “delta wave.” Patients with an accessory pathway capable only of retrograde conduction are said to have a concealed bypass tract, because a delta wave is not seen during sinus rhythm. * * Wolff-Parkinson-White syndrome: Ablation of Accessory Pathway Radio frequency ablation of the accessory pathway is often indicated in patients with WPW who are at risk of sudden death due to atrial fibrillation with a rapid ventricular response via the bypass tract. Note the disappearance of the preexcitation delta wave in the QRS with catheter ablation. * Atrial Flutter Atrial flutter is a form of reentry or circus tachycardia that utilizes the anatomy of the right atrium to sustain a loop of continuous depolarization. The loop is most typically counter-clockwise around the annulus of the tricuspid valve, following up the atrial septum and down the crista terminalis. Though the left atrium is depolarized, it is not part of the reentry circuit. Variable degrees of AV block may exist during atrial flutter (4 to 1 in this case) but this does not affect the flutter mechanism. On the ECG, note the saw-tooth shaped P wave, negative in leads II, III, and aVF, which indicates the retrograde conduction up the atrial septum, consistent with counter-clockwise flutter. * Typical and Atypical