Pacemakers and Defibrillators

Question 1

What general conditions merit implantation of a pacemaker?

Answer 1

Symptomatic Bradycardia ( 3 seconds
AV block > 3 seconds

Question 2

What are general Class III considerations for PM implantation?

Answer 2

Asymptomatic 1st degree bradyarrhythmias

Blocks expected to resolve and unlikely to recur (drug toxicity, Lyme Disease), just remove the causative agent.

Certain medications that may cause the bradyarrhythmia are necessary for survival and this is an exception to class III

Question 3

What qualifies as class I in regards to Carotid Sinus Syncope and Vasovagal Syncope?

Answer 3

Recurrent syncope

Asystole > 3 seconds

Question 4

What qualifies as class I in regards to AV block?

Answer 4

Recurring 2nd with bilateral BBB

3rd degree block

Question 5

What are 3 reasons for implanting Cardiac Defibrillators (ICDs)?

Answer 5

1. Prevent Sudden Cardiac Death
2. Left Ventricular Ejection Fraction < 35%
3. Improve Survival better than medication

Question 6

When should an ICD be placed in a patient with VT?

Answer 6

If the VT is persistent and longer than 3 seconds

Question 7

What causes inhibition of an implantable PM?

Answer 7

Pacemaker senses intrinsic activity so it only paces when there is a lack of P or R waves. If no P wave occurs (no atrial depolarization), then the PM fires and usually EKG shows inverted P wave due to PM placement.

Question 8

When is asynchronous pacing used?

Answer 8

Mainly in OR to maintain a constant beat. Either VOO or DOO used. Also used as failsafe in other PM if they fail (accidental magnetic inactivation).

This type of PM doesn’t sense, it just sets a constant pace regardless of the patient’s HR.

Question 9

When would you place a PM to pace the ventricles and not the Atria?

Answer 9

During atrial fib or flutter