13. Ventricular Arrhythmias & AV Blocks Flashcards Preview

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Flashcards in 13. Ventricular Arrhythmias & AV Blocks Deck (16):

What are the characteristics of ventricular arrhythmias?

  • Lack of a preceding P wave
  • Wide QRS > 0.12 secs
  • (in most ventricular beats) depolarization and repolarization are in opposite direction


What defines a bundle branch block?

  • QRS intervals greater than or equal to 0.12 sec
  • IS preceded by a physiologic P wave


What distinguishes a bundle branch block from ventricular ectopic beats? Similarities?

  • Both feature wide QRSs
  • Ventricular ectopics lack preceding P waves and usually come and go against the backdrop of a sinus rhythm


What is the most common and least concerning ventricular arrhythmia?



What characterizes a PVC?

  • Beat arrives early relative to background rhythm
  • Lacks a preceding P wave
  • QRS is wide


What characterizes a unifocal PVC?

  • Same configuration
  • From one focus in the ventricle

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What characterizes a multifocal PVC?

2 configurations --> indicate 2 diff ventricular foci

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What is bigeminy? What does it look like on an ECG?

PVC in which every other beat is ventricular in origin

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What is trigeminy? What does it look like on an ECG?

Every 3rd beat is ventricular

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What are some consequences of PVCs? 

  • Very frequent PVCs may be indicative of ischemia, valve disease, or infection of the heart
  • PVCs don't benefit from full diastolic filling time and lack atrial priming --> rhythms above may impair CO or BP (esp. in older patients)


What characterizes an idioventricular rhythm?

  • Slow HR (below 30 bpm) b/c higher pacemakers aren't functioning
  • No P waves
  • Wide QRS

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What characterizes ventricular tachycardia?

  • Greater or equal to 3 PVCs in a row
    • Wide QRS
    • no P wave
  • Rate > 100 bpm

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What do sustained runs of ventricular tachycardia look like? Significance?

First BP falls, then CO decreases --> person passes out

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What is the R on T phenomenon? What does it look like on an ECG? Significance?

  • PVC falls on the terminal 1/2 of the T wave --> ventricle may only be partially repolarized
  • Sets the stage for re-entrant, "circus" tachycardia
  • May precipitate ventricular tachycardia

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What is ventricular fibrillation? Significance?

  • Ventricles become unsynchronized b/c small populations of cells depolarize randomly
  • No functional contraction occurs ---> no CO
  • Pre-fatal condition
    • Defibrillation is URGENT

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1° AV block? Nature of prob? ECG characteristics?  

  • Nature: fixed delay in AV conduction 
  • ECG criteria:
    • P:QRS ratio is still 1:1
    • PR interval > 0.20 s
    • Regular QRS

(pictured: lead V1)

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