Pacemakers, AICDs
Type
Links
Permanent
Nomenclature - Magnets - Electrocautery - Preop - Intraop
Temporary
Methods and Uses
AICDs
Nomenclature - Other Points

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(from Tom VerLee's and Hugh Allen's sites and Mike Stella, MD)


Pacemakers: Nomenclature
Pacers use a 5-letter code: first 3 letters most important

  1. First Letter: Chamber Paced

  2. A= Atrium
    V= Ventricle
    D= Dual (A+V)
  3. 2nd Letter: Chamber Sensed

  4. A= Atrium
    V= Ventricle
    D= Dual (A+V)
    O= None
  5. 3rd Letter: Response after Sensing:

  6. I = Pacing Inhibited
    T= Pacing Triggered
    D= Dual (I+T)
    O= None
  7. 4th Letter: Programmability

  8. P = Rate & Output
    M = Multiprogramable
    C = Communicating
    R = Rate adaptive
    O = None
  9. 5th Letter: Arrhythmia Control

  10. P = pacing
    S= shock
    D= Dual (P+S)
    O = None
Other Terms: Examples:

VVI = Ventricle paced, ventricle sensed; pacing inhibited if beat sensed.
VVIR = Demand ventricular pacing with physiologic response to exercise.
DDD = Atrium & ventricle can both be paced; atrium & ventricle both sensed; pacing triggered in each chamber if beat not sensed
DDDR = AV concordance with physiologic response.

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Pacemakers: Magnets

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Pacemakers: Electrocautery

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Pacemakers: Preoperative Evaluation
Ask Cardiology to evaluate/ re-program pacer for surgery.

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Pacemakers: Intra-Operative Management

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Temporary Pacing Techniques
Method Chambers Paced Uses
Transcutaneous Right Ventricle Arrest; Intraoperative and Prophylactic
Transesophageal Left Atrium Prophylactic atrial; intraop; overdriveSVT
Transvenous semirigid Atrium and/or Vent Arrest; prophylactic; maintenance
Transvenous flow-directed Right Ventricle Arrest; intraoperative;prophylactic; maintenance
Pacing PAC Atrium and/or Vent Arrest; intraoperative; prophylactic;maintenance
Epicardial Atrium and/or Vent Arrest; prophylactic; maintenance
Transthoracic Ventricle Arrest only

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Automatic Implantable Cardioverter-Defibrillator
AICDs: Nomenclature
Position I Position II Position III Position IV
Chamber(s) shocked Antitachicardia pacing chamber(s) Tachycardiadetection Antibradycardia pacing chamber(s)
O=None O=None E=Electrogram O=None
A=Atrium A=Atrium H=Hemodynamic A=Atrium
V=Ventricle V=Ventricle V=Ventricle
D=Dual D=Dual D=Dual

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AICDs: Additional points:
1. Newer devices can deliver “tiered therapy” (pacing, then increasing shocks)
2. Devices measure R-R interval over time
3. Pacemakers can function in presence of ICD as long as electrodes are bipolar.
4. Most ICDs have backup VVI pacing to protect against post shock bradycardia.
5. Magnet application in most newer models will suspend tachyarrhythmia detection.  This should be done before induction of anesthesia.

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