Temporary Pacemaker Modes

Question 1

What does AAI stand for in pacing modes?

Answer 1

The atrium is paced, the atrium is sensed and inhibition of pacing occurs in response to sensing.

Question 2

List the indications for AAI pacing mode.

Answer 2

• Severe sinus bradycardia
• Sinus bradycardia with poor cardiac output
• Prevention of postoperative AF

Question 3

What does VVI stand for in pacing modes?

Answer 3

The ventricle is paced, the ventricle is sensed and inhibition of pacing occurs in response to sensing.

Question 4

What does DDD mode in pacing entail?

Answer 4

Both the atrium and ventricle are sensed and paced. Either may be inhibited in response to sensing.

Question 5

Explain the trigger mechanism in DDD pacing.

Answer 5

If the sensed atrial rate is faster than the set pacemaker rate and no ventricular depolarisation occurs within the set AV interval, the ventricular wire will pace the ventricle at the sensed atrial rate.

Question 6

What is the difference between DDD and DDI pacing modes?

Answer 6

In DDI mode, unlike DDD mode, if the sensed atrial rate is faster than the set pacemaker rate, no ventricular pacing will occur in response to the sensed intrinsic atrial activity provided each depolarisation is conducted to the ventricles.

Question 7

What does VOO mode indicate?

Answer 7

The ventricle is paced asynchronously at the set rate. There is no sensing.

Question 8

List the indications for using VOO mode.

Answer 8

• Patients at high risk of, or established AVB
• Ventricular standstill
• Patients without atrial wires with an inadequate heart rate
• High-grade AVB
• Asystole
• Sinus bradycardia with high risk of AVB

Question 9

What does DOO mode entail?

Answer 9

Both the atrium and ventricle are paced at the set rate, with a set AV interval between the two. There is no sensing.

Question 10

List the indications for DOO pacing mode.

Answer 10

• Patients with improved cardiac function needing protection from bradycardia and high-grade AVB
• Patients with recurrent, paroxysmal AF or atrial flutter with an inadequate ventricular rate
• Previous episode(s) of pacemaker-mediated tachycardia in DDD mode
• Emergency use
• Weaning from bypass with only ventricular wire(s)
• Pacing dependence when diathermy is in use

Question 11

What are relative contraindications for pacing modes?

Answer 11

• High-grade AVB
• High risk of high-grade AVB (DDD/DDI/VVI may be preferred)
• AF
• Poor sensing in the atrial wire(s)

Question 12

True or False: Pacemaker-mediated tachycardia can occur if not easily remedied by adjusting refractory periods.

Answer 12

True