Pacemakers, Internal Cardioverter-Defibrillator Management

Question 1

What do the 5 digits of the pacemaker stand for and what are the options

Answer 1

VVIOO

1st digit: Chamber paced O / A / V / D
2nd digit: Chamber sensed O / A / V / D
3rd digit: Response to sensing O / T / I / D
4th digit: Rate Modulation O / R
5th digit: Multisite pacing O / A / V / D

O = None
A = Atria
V = Ventricles
D = Dual
R = Rate modulation
I = Inhibited
T = Triggered

Question 2

What are the perioperative precautions to avoid intra-operative malfunctioning of the pacemaker

Answer 2

Preoperative

1. Identify type
2. Contact cardiologist: device function and history

Intraoperative

1. Advise use of bipolar diathermy only
2. Grounding pad as distal as possible from EICD
3. Temporary pacing/defibrillation resources available
4. If pacer dependent –> asynchronous mode
5. Consider magnet application to disable anti-tachycardia function

Postoperative
1. Continue monitoring with available pacing/defibrillating until therapeutic functions of the device restored and its function confirmed.

Question 3

Why is diathermy problematic with ICDs?

Answer 3

1. Interpret cautery as VF
2. Inhibit pacemaker function due to cautery artifact
3. Increase pacing rate due to activation of the rate-responsive sensor
4. Temporarily or permanently