Pacing Mode |
Description |
Advantages |
Disadvantages |
AOO |
asynchronous atrial pacing. |
- Only one lead required
- Preserves AV synchrony in the presence of an intact AV node
- Protects against interference by diathermy
|
- contraindicated in the presence of intrinsic cardiac rhythms.
- If the rate is not high enough, you will have an underlying rhythm competing with the pacemaker.
- Useless if the AV node is dysfunctional
- Useless in the presence of AF
- Increased risk of perforating the thin atrial wall
|
AAI |
atrial demand pacing |
- Only one lead required
- Preserves AV synchrony in the presence of an intact AV node
- Only paces on demand; allows intrinsic rhythm while the rate is high enough
|
- Useless if the AV node is dysfunctional
- Useless in the presence of AF
- Increased risk of perforating the thin atrial wall
|
AAT |
atrial pacing |
- Only one lead required
- Preserves AV synchrony in the presence of an intact AV node
- Useful for testing atrial sensing (using the pacing spike)
|
- Useless if the AV node is dysfunctional
- Useless in the presence of AF
- Unproductive in general (paces in response to normal atrial contraction, while the atrium is in a refractory period); thus, not a useful permanent mode
- Increased risk of perforating the thin atrial wall
|
VOO |
asynchronous ventricular pacing |
- Only one lead required
- Protects against interference by diathermy
|
- Asynchronous AV contraction
- May result in the R - on - T phenomenon
- Difficult to assess ST changes (LBBB-like QRS morphology)
|
VVI |
ventricular demand pacing |
- Only one lead required
- Only paces on demand; allows intrinsic rhythm while the rate is high enough
|
- Asynchronous AV contraction
- Difficult to assess ST changes (LBBB-like QRS morphology)
|
VVT |
ventricular pacing |
- Useful for testing ventricular sensing (using the pacing spike)
|
- Asynchronous AV contraction
- Unproductive in general (paces in response to normal ventricular contraction, while the ventricle is in a refractory period); thus, not a useful permanent mode
- Difficult to assess ST changes (LBBB-like QRS morphology)
- Possibility of "endless loop" tachycardia
|
VAT |
atrial sensing, ventricular pacing |
- AV synchrony is preserved
- "Pacemaker syndrome" is thus avoided
- Advantageous in patients with normal atrial activity and a dysfunctional AV node
|
- Two leads required
- Bundle of His is bypassed
- Difficult to assess ST changes (LBBB-like QRS morphology)
- Increased risk of perforating the thin atrial wall
|
DDD |
dual chamber demand pacing |
- AV synchrony is preserved
- "Pacemaker syndrome" is thus avoided
- Advantageous in patients with normal atrial activity and a dysfunctional AV node
- Versatile mode, with hemodynamic advantage
|
- Two leads required
- Bundle of His is bypassed
- Possibility of "endless loop" tachycardia
- Increased risk of perforating the thin atrial wall
|