Cardiac pacing

Question 1

What is the intrinsic rate of the SA node?

Answer 1

60-70min-1

Question 2

What is the intrinsic rate of the purkinje fibres?

Answer 2

0-30min-1

Question 3

What is the intrinsic rate of the AV junctional region?

Answer 3

40-50min-1

Question 4

What kind of CHB requires pacing?

Answer 4

broad-complex

the occurence of long pauses >3 s makes this need urgent

Question 5

Why should transcutaenous pacing be used as briefly as possible?

Answer 5

It does not produce reliable ventricular stimulation

Question 6

When should percussion pacing be performed?

Answer 6

When bradycardia is so profound it causes cardiac arrest

more likely to be successful when ventricular standstill is accompanied by continuing p wave activity

Question 7

How is percussion pacing performed?

Answer 7

1. With the sides of a closed fist deliver repeated thumps to the praecordium (lateral to the lower left sternal edge)
2. raise the hand about 20cm in between thumps
3. monitor the ECG and assess whether a QRS complex is generated (if possible this should be a second person)
4. if initial thumps do not produce a QRS complex try using slightly harder thumps
5. if this still fails to produce a QRS move the point of contact until a point is found that produces ventricular stimulation

Question 8

What are the advantages of transcutaenous pacing as opposed to transvenous?

Answer 8

• It can be established very quickly
• it is widely available
• it is easy to perform and requires minimum tracing
• it can be initiated by healthcare providers whilst awaiting transvenous pacing

Question 9

What is the major disadvantage of transcutaenous pacing?

Answer 9

In a conscious patient it is very uncomfortable

Question 10

What should you bear in mind if your pacing device cannot defibrillate?

Answer 10

Position AP so that you can still defibrillate

Question 11

If artefact is continuing to prevent your pacing device from working- what should you do?

Answer 11

Switch it to deliver fixed-rate pacing

Question 12

What is usually an appropriate pacing range?

Answer 12

60-90

Question 13

If the pacing device has an adjustable energy output what should you do?

Answer 13

Set it to its lowest value and turn on the pacemaker
Gradually increase the output whilst observing the patient and the ECG
Increase the current until each pacing spike is followed by a QRS

Question 14

How do you know if your QRS complex is genuine and not artefact?

Answer 14

It is followed by a T wave and generates a pulse

Question 15

If the highest current setting is reached and capture has not occured, what should you do?

Answer 15

change the electrode positions

continued failure to capture may indicate mypcardial inviability or hyperkalaemia

Question 16

Should you perform CPR while pacing?

Answer 16

You can but there is no benefit, best to turn off the pacer

Question 17

What should be done when an adequate cardiac output is generated via trans-cutaenous pacing

Answer 17

seek expert help to establish transvenous pacing

Question 18

What are the three ways temporary transvenous pacing methods can fail?

Answer 18

1. high threshold
2. connection failure
3. lead displacement

Question 19

What is the aim for the threshold of transvenous pacing

Answer 19

<1.0 V

Question 20

When is it normal to pace the heart at higher thresholds?

Answer 20

Over the first days and weeks after insertion

Question 21

How often should the threshold on temporary pacing leads be checked?

Answer 21

Daily

Question 22

If loss of capture occurs bevause of a high threshold what should you do?

Answer 22

• increase the output of the pacemaker to well about the threshold
• obtain a CXR and get expert help

Question 23

What is connection failure seen as on ECG

Answer 23

Absence of pacing spike

Question 24

What should you do if there is a absence of a pacing spike?

Answer 24

Check pacemaker is on
Check connectoins
Chack batteries aren’t deplete
Try another pacing box

Question 25

Where is the tip of an endocardial transveour ventricular pacing lead normally placed?

Answer 25

Apex of the right ventricle

Question 26

If a patient with a recently inserted pacemaker suffers a PEA cardiac arrest what should be considered?

Answer 26

Perforation of the myocardium and tamponade

Question 27

What is likely to be seen on an ECG in lead displacement

Answer 27

A pacing spike with intermittent or complete loss of capture

Question 28

What should be done if transvenous pacing has caused asystole

Answer 28

Use transcutaenous until pacing can be re-established

Question 29

When is lead displacement less likely after permanent pacemaker insertion?

Answer 29

After 4-6 weeks

Question 30

What can trigger a fracture of a permanent pacing lead?

Answer 30

foosh on the side of the pacemaker

Question 31

What kind of pacemakers are undetactable on examination?

Answer 31

Leadless pacemakers

Question 32

How far away should defibrillation pads be placed from an ICD?

Answer 32

> 8cm

Question 33

When should you consider deactivating an ICD in CPR

Answer 33

If it delivers repeated inappropriate shocks that are impeding delivery of high quality CPR