• Syncope in Elderly
  • Syncope =  decrease in brain perfusion leading to loss of postural tone
  • Neurally mediated (neurocardiogenic syncope, carotid hypersensitivity)
  • Orthostasis (PD c/b ANS dysfcn, multi-system atrophy, drugs, DM)
  • Arrhythmia (Afib, AV block, SSS, VT)
  • CV/structural (MI, AS, PE)
  
  

  Posted 11/07/16 09:14:15 AM by Matthew Cummings

• Characteristics of Complete Heart Block
  • More P waves than QRS complexes exist and no relationship (AV dissociation) exists between them.
  • Escape rhythm may arise within the AV node (resulting in a narrow QRS complex), or lower in the conduction system (producing a wide QRS complex). 
  • The ventricular rate varies from 30–40 beats/min.
  •  Atrial rate is faster than the ventricular rate (60–100 beats/min) presumably in response to the hemodynamic consequences of the block (relative hypotension). 
  
  

  Posted 11/07/16 09:21:07 AM by Matthew Cummings

• Accelerated junctional rhythm 
  • Rate of an AV junctional pacemaker exceeds >> rate of sinus node due to increased automaticity in AV node + decreased automaticity in sinus node.
  • Narrow complex (QRS < 120ms), ventricular rate ~60 – 100 bpm
    • Retrograde P waves may be present (inverted in the inferior leads, upright in aVR + V1).
    • AV dissociation may be present with the ventricular rate usually greater than the atrial rate.
      • Junctional Escape Rhythm: 40-60 bpm
      • Accelerated Junctional Rhythm: 60-100 bpm
      • Junctional Tachycardia: > 100 bpm
  • Causes of junctional rhythms
    • Digoxin toxicity 
    • Myocardial ischaemia
    • Myocarditis
    • Cardiac surgery (classically mitral valve)
  
  

  Posted 11/07/16 09:28:09 AM by Matthew Cummings

• When to consider PPM?
  • Symptomatic bradycardia that cannot be reversed (meds, electrolytes, etc)
  • Mobitz II or CHB even if asymptomatic (ventricular/junctional escape = unreliable = high-risk for hemodynamic collapse)
  • Formal indications below
  
  
  
  

  Posted 11/07/16 09:43:53 AM by Matthew Cummings

• For further reading...

  AHA/ACC/HRS PPM Guidelines
  LITFL EKG Review -- Accelerated junctional rhythm
  
  
  
  

  Posted 11/07/16 09:46:33 AM by Matthew Cummings

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