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Conduction Disturbances

Conduction Disturbances

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Conduction Disturbances

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  1. Conduction Disturbances

  2. Only single shape P Sinus bradycardiasinus tachycardia…sinus dysrhythmia (arhythmia)sinus pause (arrest)sinoatrial block

  3. SINUS DYSRHYTHMIA Some variation in the sinus node discharge rate is common, but if the variation exceeds 0.12 s between the longest and shortest intervals, sinus dysrhythmiais present. The ECG: (1) normal sinus P waves and P-R intervals, (2) 1:1 AV conduction, and (3) variation of at least 0.12 s between the shortest and longest P-P interval

  4. Sinus Arrhythmia

  5. Sinus dysrhythmia:(note slight irregularity).

  6. Sinus Arrest (Pause) Sinus pause is a failure of impulse formation within the sinus node. In sinus arrest, the P-P interval has no mathematical relation to the basic sinus node discharge rate

  7. s. dysrhythmiavs s. arrest? Sinus dysrhythmia : irregular-irregular Sinus Arrest (Pause): regular-irregular

  8. The pause is not equal to exactly two or more)3,4,…) cardiac cycles of the underlying rhythm.

  9. Sinoatrial Block

  10. pause In a sinus exit block the pause is equal to exactly two or more cardiac cycles of the underlying rhythm. The electrical impulse from the SA node is blocked and not conducted to the atria.

  11. Sino Atrial Exit Block • Implies that there is delay or failure of a normally generated sinus impulse to exit the nodal region. • First degree SA block:slowed conduction • Second degree SA block:intermittent conduction 1.Type 1 (Mobitz 1) 2.Type 2 (Mobitz 2) • Third degree SA block: complete conduction failure

  12. First Degree Sino Atrial Exit Block • Implies that the conduction time where each impulse leaving the node is prolonged • This problem cannot be observed on surface EKG • Electro physiology study needed to measure the sinoatrial conduction time

  13. Second Degree Sino Atrial Exit Block • Type I (SA Wenckebach) 1.PP intervals gradually shorten until a pause occurs (i.e., the blocked sinus impulse fails to reach the atria) 2.The pause duration is less than the two preceding PP intervals 3.The PP interval following the pause is greater than the PP interval just before the pause

  14. SA Wenckebach X Y Z X>Y Z<2X Z<2Y

  15. SA Block type1 vs S. Pause? Both irregular-irregular SA Block type1: 1.PP intervals gradually shorten until a pause occurs 2.The pause duration is <2 PP 3.The PP interval following the pause > PP interval just before the pause

  16. Second Degree Type II SA Block • PP intervals fairly constant (unless sinus arrhythmia present) until conduction failure occurs. • The pause is approximately twice the basic PP interval

  17. Third Degree Or Complete Sino Atrial Exit Block • May Cannot be distinguished from a prolonged sinus pause or arrest • According to below foci or escape rhythm ECG is variable! • Can be identified from direct recording of sinus node pacemaker activity during an EP study

  18. RosenSinoatrial Block and Escape Rhythms Incomplete SA block is diagnosed when an occasional P wave is dropped from the normal P-QRS-T sequence on the ECG. There are no P waves on the ECG complete SA block (sinus arrest). Usually, a lower pacemaker emerges in complete SA block; if this pacemaker is within the AV node, the QRS complex is narrow and results in an "idiojunctional“escape rhythm at a rate of 45 to 60 beats/min.

  19. SA Block type2 vs SA arrest? Both regular-irregular PP’ = 2 x PP >>> SA Block type2

  20. The pause is not equal to exactly two or more)3,4,…) cardiac cycles of the underlying rhythm.

  21. Dx Regular-Irregular Or Irregular-Irregular Regular-Irregular: SA Block type2 or SA arrest PP’ = 2 x PP >>> SA Block type2 Irregular-Irregular: SA Block type1 vs S. arrhythmia

  22. Sick Sinus Syndrome • All result in bradycardia • Sinus bradycardia (rate of ~43 bpm) with a sinus pause • Often result of tachy-brady syndrome: where a burst of atrial tachycardia (such as afib) is then followed by a long, symptomatic sinus pause/arrest, with no breakthrough junctional rhythm.

  23. SSS

  24. Sick sinus syndrome is an indication for a permanent pacemaker. Pharmacologic treatment of atrialtachyarrhythmias carries the risk of aggravating preexisting AV block or sinus arrest. Therefore, most patients should have pacemaker implantation beforedrug therapy is begun.

  25. Only single shape P

  26. Atrial Dysrhythmias Atrialdysrhythmiashave ECG features similar to those of sinus dysrhythmias, except an atrial source serves as the pacemaker, producing P' waves that are different from the sinus P waves. The P'R interval may also vary from the normal sinus PR interval, which distinguishes these rhythms.

  27. PAC non-compensatory pause MAC Wandering pacemaker

  28. MAT

  29. AV Blocks: Divided in to incomplete and complete block • Incomplete AV block includes a. first-degree AV block b. second degree AV block c. advanced AV block • Complete AV block,also known as third degree AV block

  30. Location of the Block • Proximal to, in, or distal to the His bundle in the atrium or AV node • All degrees of AV blocks may be intermittent or persistent

  31. First Degree AV Block • PR interval is prolonged 0.21- 0.40 seconds, but no R-R interval change • Normal=0.10”-0,20”

  32. Second-Degree AV Block • There is intermittent failure of the supraventricular impulse to be conducted to the ventricles • Some of the P waves are not followed by a QRS complex.The conduction ratio (P/QRS ratio) may be set at 2:1,3:1,3:2,4:3,and so forth

  33. Types Of Second-Degree AVBlock:I and II • Type I also is called Wenckebach phenomenon or Mobitz type I and represents the more common type • Type II is also called Mobitz type II

  34. Type I Second-Degree AV Block: Wenckebach Phenomenon • ECG findings 1.Progressive lengthening of the PR interval until a P wave is blocked 2.Progressive shortening of the RR interval until a P wave is blocked 3.RR interval containing the blocked P wave is shorter than the sum of two PP intervals

  35. Type II Second-Degree AVBlock:Mobitz Type II • ECG findings 1.Intermittent blocked P waves 2.PR intervals may be normal or prolonged,but they remain constant 3.When the AV conduction ratio is 2:1,it is often impossible to determine whether the second-degree AV block is type I or II 4. A long rhythm strip may help

  36. High-Grade or Advanced AV Block • When the AV conduction ratio is 3:1 or higher,the rhythm is called advanced AV blocked • A comparison of the PR intervals of the occasional captured complexes may provide a clue • If the PR interval varies and its duration is inversely related to the interval between the P wave and its preceding R wave (RP), type I block is likely • A constant PR interval in all captured complexes suggests type II block