Cardiac pacing

Question 1

What is the primary purpose of non-invasive pacing in cardiac arrest settings?

Answer 1

To maintain cardiac output temporarily while expert help is obtained.

Question 2

What is the heart’s natural pacemaker called?

Answer 2

Sino-atrial (SA) node.

Question 3

Define ‘automaticity’ in the context of cardiac tissue.

Answer 3

The ability of cardiac tissue to initiate a heartbeat spontaneously.

Question 4

What is the usual intrinsic rate of the SA node at rest?

Answer 4

60–70 min-1.

Question 5

What happens in complete heart block (CHB) at the level of the AV node?

Answer 5

The most rapid automatic activity arises from cells immediately below the block.

Question 6

List some causes of complete heart block.

Answer 6

• Degenerative conducting tissue fibrosis
• Extensive anteroseptal myocardial infarction
• Cardiomyopathies
• Calcific valve disease.

Question 7

What is the risk associated with automatic activity arising below a block in the distal Purkinje fibres?

Answer 7

It is likely to be slow and unreliable.

Question 8

True or False: Transcutaneous pacing is effective in asystole without P waves.

Answer 8

False.

Question 9

What are the two main methods of pacing?

Answer 9

• Non-invasive
• Invasive.

Question 10

What is percussion pacing also known as?

Answer 10

Fist pacing.

Question 11

How should percussion pacing be performed?

Answer 11

Deliver repeated firm thumps to the praecordium with a closed fist.

Question 12

What is a major disadvantage of transcutaneous pacing?

Answer 12

Discomfort to the conscious patient.

Question 13

What is demand pacing in transcutaneous pacing?

Answer 13

The device detects spontaneous QRS complexes and delivers pacing stimulus only when needed.

Question 14

What should be done if pacing does not achieve electrical capture?

Answer 14

Try changing the electrode positions.

Question 15

Fill in the blank: The pacing impulse in transcutaneous pacing stimulates painful contraction of _______.

Answer 15

chest wall muscles.

Question 16

What should be monitored to confirm effective pacing?

Answer 16

A palpable pulse following each paced QRS complex.

Question 17

How can temporary transvenous pacing systems fail?

Answer 17

• High threshold
• Displacement of the lead
• Failure to capture.

Question 18

What is the appropriate pacing rate range for adults during transcutaneous pacing?

Answer 18

60–90 min-1.

Question 19

What is the risk of long ventricular pauses (> 3 s) during cardiac pacing?

Answer 19

It implies a risk of asystole.

Question 20

What should be done if transcutaneous pacing is needed during chest compressions?

Answer 20

Turn off the pacemaker during CPR.

Question 21

What indicates electrical capture during pacing?

Answer 21

A pacing spike followed immediately by a QRS complex.

Question 22

What should be provided to conscious patients undergoing transcutaneous pacing?

Answer 22

Intravenous analgesia and/or sedation.

Question 23

What is the purpose of pacing threshold in cardiac pacing?

In transvenous pacing

Answer 23

To determine the minimum voltage needed to stimulate the ventricle.

The usual aim is to achieve a threshold of < 1.0 V at the time of lead insertion.

Question 24

What happens if the pacing threshold is high?

Answer 24

Suggests that the electrode is not making satisfactory contact with the myocardium.
I.e. move the lead

Question 25

What is loss of capture in cardiac pacing?

Answer 25

When a pacing spike is not followed by a QRS complex. ## Footnote This may occur intermittently and should prompt a check of the pacing threshold.

Question 26

What should be done if there is loss of capture due to a high threshold?

Answer 26

Increase the output of the pacemaker immediately. ## Footnote A sudden increase in pacing threshold may indicate lead displacement.

Question 27

What is the usual configuration of temporary transvenous pacing leads?

Answer 27

Bipolar, with one electrode at the tip and another approximately 1 cm proximal. ## Footnote Each electrode connects to separate connectors at the pacemaker.

Question 28

What can cause pacing failure?

Answer 28

Connection failure between the lead and the pacemaker. ## Footnote This may result in absence of a pacing spike on the ECG.

Question 29

What is the risk associated with lead displacement of a pacing lead?

Answer 29

It may cause ventricular extrasystoles or serious arrhythmias like VT and VF. ## Footnote This can lead to ventricular standstill or cardiac arrest.

Question 30

What are the indications for ICD implantation?

Answer 30

* Primary prevention in high-risk patients * Post-myocardial infarction * Heart failure patients * Certain inherited cardiac conditions ## Footnote Guidelines define specific indications for these devices.

Question 31

What should be done if an ICD delivers inappropriate shocks?

Answer 31

Temporarily disable it using a ring magnet. ## Footnote This prevents the ICD from recognizing and shocking VF and VT.

Question 32

What should be checked during the ABCDE approach for a patient with an implanted device?

Answer 32

The presence of the implanted device and its type (pacemaker or ICD). ## Footnote Establish whether it was for bradyarrhythmia or heart failure.

Question 33

What precautions should be taken when defibrillating a patient with an implanted pacemaker or ICD?

Answer 33

Place defibrillation pads at least 10–15 cm from the device. ## Footnote Use A-P positions if the device is below the right clavicle.

Question 34

What is the purpose of biventricular pacing systems?

Answer 34

To improve coordination of left ventricular contraction in heart failure patients. ## Footnote They are used even in patients who do not require pacing for bradycardia.

Question 35

What should be done after the death of a person with an active ICD?

Answer 35

Arrange for its deactivation before removal or autopsy. ## Footnote All implanted electronic devices must be removed prior to cremation.

Question 36

True or False: Problems with permanent pacing systems are common.

Answer 36

False. ## Footnote Problems are rare due to more secure connections.