Pacemakers

Question 1

What is a pacemaker?

Answer 1

Device to stimulate cardiac activity.

Question 2

Don’t we already have pacemakers?

Answer 2

Yes, but sometimes the don’t work so well.

Question 3

What two basic functions do pacemakers perform?

Answer 3

Sense cardiac activity

Pace

Question 4

What are the basic components of pacemakers?

Answer 4

Generator and lead wires; those can be epicardial or endocardial.

Question 5

What are the two basic categories of generators?

Answer 5

External and implantable

Question 6

What other function might the generator provide besides routine pacing?

Answer 6

De-fibrillate

Question 7

What is a Reed switch?

Answer 7

Switch in pacer controlled by magnetic field through skin.

Question 8

What are the two fixation devices on pacer leads?

Answer 8

Tines and screws

Question 9

Where is a pacemaker generator usually installed?

Answer 9

Under skin below left clavicle.

Question 10

Name some indications for pacing:

Answer 10

Brady or tachy arrhythmias; 3rd degree heart block; cardiac surgery; asystole: heart dependent on pacer for any activity at all.

Question 11

What is capture?

Answer 11

The pacer is able to bring about cardiac activity. (depolarization)
ECG will show if capture is effective.

Question 12

What is capture dependent on?

Answer 12

Voltage; Condition of myocardium; Lead resistance

Question 13

How do we know when we have capture?

Answer 13

Pacing spike is followed by a depolarization: QRS or P, depending

Question 14

Define under-sensing:

Answer 14

Pacer doesn’t recognize intrinsic cardiac activity

Threshold too high

Question 15

Define over-sensing:

Answer 15

Pacer responds to non-cardiac signals (hair-trigger)

Threshold too low

Question 16

How do we recognize when proper capture isn’t happening?

Answer 16

Spike NOT followed by appropriate ECG activity.

Question 17

What do the letters of the first, second, and third letters in the function code mean?

Answer 17

PSR: chamber paced (A or V or Dual); chamber sensed ( A or V or Dual); and response (Inhibit or Trigger)

Question 18

How would a VVI pacemaker work?

Answer 18

Paces the ventricles, senses the ventricles, doesn’t pace if ventricles depolarize on their own.

Question 19

How would a VAT work?

Answer 19

Paces ventricles; senses atria; paces when atrial depolarization is sensed.

Question 20

How would DDD work?

Answer 20

Paces both, senses both.

Both responses are possible.

Question 21

How would AAI work?

Answer 21

Paces atria; senses atria; doesn’t pace if atrial activity is sensed.

Question 22

How are pacemakers programmed once implanted under the skin?

Answer 22

Magnetic pulses

Question 23

What is a fusion beat?

Answer 23

Paced beat created along with intrinsic

Question 24

What does a fusion beat look like on ECG?

Answer 24

Paced and intrinsic beats squashed together. Merged.

Question 25

What goes wrong with pacers most often?

Answer 25

Lead wire damage

Question 26

What is “twiddlers syndrome”?

Answer 26

Patient absent mindedly twiddles wires under skin, possibly damaging the wires.