wolff-parkinson-white and atrioventricular (av) heart blocks

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Wolff-Parkinson-White and Atrioventricular (AV) Heart Blocks. Chapters 12 and 17. Wolff-Parkinson-White. Chapter 12. Artrioventricular Bypass Tract. Accessory pathways form and fail to disappear during fetal development Formed near the mitral or tricuspid valves or interventricular septum - PowerPoint PPT Presentation


  • Wolff-Parkinson-White and Atrioventricular (AV) Heart Blocks Chapters 12 and 17

  • Wolff-Parkinson-White Chapter 12

  • Artrioventricular Bypass TractAccessory pathways form and fail to disappear during fetal developmentFormed near the mitral or tricuspid valves or interventricular septumAn AV bypass tract is sometimes referred to as the bundle of Kent

  • Artrioventricular Bypass TractFrom SA node directly to AV node AND to ventricular myocardiumPartially bypassing the bundle of His and purkinje fibers

  • Accessory Pathways

  • Wolff-White-ParkinsonWide QRSdue to early depolarization not due to a delay in depolarizationShortened PR intervalUpstroke QRS complex is slurred; delta wave

  • Wolff-Parkinson-WhiteAs a general rule: the initial QRS complex (delta wave) vector will point away from the area of the ventricles that is first to be stimulated by the bypass tractF.Y.I.

  • Wolff-Parkinson-WhiteBypass TractsLeft Lateral negative delta waves in I and/or aVL and positive in V1Posteriorpositive delta waves in most of the precordial (chest) leads and negative in the inferior leadsRightnegative delta waves in V1 and V2 and positive in I and V6Anteroseptal (anterior)negative delta waves in leads V1 and V2F.Y.I.

  • WPW SignificanceMore prone to arrhythmias especially SVTOften mistaken for RBBB or LBBB or an MI

  • AV Heart BlockChapter 17*

  • Classification of AV Heart Blocks

    DegreeAV Conduction Pattern1St Degree BlockUniformly prolonged PR interval2nd Degree, Mobitz Type IProgressive PR interval prolongation2nd Degree, Mobitz Type IISudden conduction failure3rd Degree BlockNo AV conduction

  • First Degree Blocknote the prolonged PR interval

  • Second Degree AV BlockMobitz type I or WinckebachMobitz type II

  • Second Degree AV Block Type I or Wenckebach

  • Second Degree AV Block Type I or WenckebachProgressive lengthening of the PR interval from beat to beat until a beat is dropped.The PR interval after the nonconducted P wave is shorter than the PR interval before the nonconducted P wave.May be grouping of QRS complexes

  • Second Degree AV BlockType IISudden appearance of a single, non-conducted sinus P wave......without......the progressive prolongation of the PR intervals...and the shortening of the PR interval in the beat after the non-conducted P wave.

  • Second Degree AV BlockType II

  • 2:1 AV BlocksOften are type II blocks look for slightly prolonged QRSBut they can be type I blockslook at long rhythm strip Sometimes they are labeled a second degree block only

  • Advanced Second-Degree AV BlockTwo or more consecutive non-conducted sinus P wavesNote the consistent PR intervals

  • Third-Degree (Complete) AV Block

  • Third-Degree (Complete) AV BlockP waves are present, with a regular atrial rate faster than the ventricular rateQRS complexes are present, with a slow (usually fixed) ventricular rateThe P wave bears no relation to the QRS complexes, and the PR intervals are completely variable(Some properly timed P waves may be conducted)

  • Third-Degree (Complete) AV BlockQRS can be normal width or wide

  • AV DissociationSA is pacing the atriaAV is pacing the ventriclesVentricular rate is similar to atria rateNo P wave, even if properly timed, will be conducted.

  • AV Dissociation

  • AV Dissociation

  • Third-Degree (Complete) AV Block

    100 b/min42 b/minNoComplete heart block

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