Cardiac Implantable Electrical Device

Question 1

An 81-year-old male patient is listed for a transurethral resection of the prostate. He has a history of hypertension, COPD and has a permanent pacemaker in situ. You are asked to review him in the preoperative assessment clinic.

What are the indications for insertion of cardiac implantable electrical devices?

Answer 1

Permanent pacemaker (PPM):
* Atrioventricular blockade (unstable 2nd or 3rd degree).
* Sick sinus syndrome.

Biventricular pacemaker:
* Moderate/severe cardiac failure (cardiac resynchronisation therapy).

Implantable cardioverter defibrillator (ICD):
* Previous ventricular dysrhythmias with significant haemodynamic compromise or cardiac arrest.
* Post-myocardial infarction at risk of ventricular dysrhythmias.
* Familial conditions with a high risk of sudden death, including long QT syndrome, Brugada syndrome, hypertrophic cardiomyopathy
and arrhythmogenic right ventricular dysplasia.
* Congenital heart disease.

Implantable loop recorder:
* For diagnostic or monitoring purposes.

Question 2

What are the features of a permanent pacemaker?

Answer 2

• Source of energy (battery).
• Pulse generator.
• Pacing leads (unipolar or bipolar).

Question 3

How would you assess this patient preoperatively?

History:

Answer 3

• Take a thorough cardiovascular history including the extent of historical or existing cardiac disease or comorbidities. Elicit any current symptoms focusing on syncope, chest pain and palpitations, or symptoms of worsening cardiac function.
• Pacemaker review:
• Date and indication for insertion, dependency on the pacemaker,
  and underlying rhythm.
• Duration since last check.
• Any concerns or issues.
• Manufacturer and type of device, and lead and box location.
• Pacing mode, including presence of rate modulation or anti-tachycardia function.
• Patients may be able to produce their personal pacemaker ID card,
  which contains useful details regarding some of the above.
• Take a full respiratory history including any infections, hospital admissions and current symptoms.
• Non-cardiac comorbidities, social and medication history including medication compliance and anaesthetic history.

Question 4

How would you assess this patient pre-operatively?

Examination & Investigations

Answer 4

Examination:
* Cardiovascular and respiratory examinations.
* Airway assessment.

Investigations:
* Baseline observations.
* ECG (both pacing spikes and evidence of subsequent electrical complexes should be apparent).
* Echo if indicated.
* Chest X-ray to review the position of the pacemaker box, assessment
of leads, and to assess for cardiac failure.
* Bloods to include full blood count, urea and electrolytes and clotting
function, particularly if taking anticoagulants.

Question 5

The patient’s pacemaker ID card states the mode as VVIR. What does this mean?

Answer 5

• This is a five-letter code using the standard nomenclature from the Generic Pacemaker Code developed by the North American Society of Pacing and Electrophysiology and the British Pacing and Electrophysiology Group.
• The first letter denotes the chamber paced – in this case the right ventricle is paced.
• The second letter denotes the chamber sensed – in this case the right ventricle.
• The third letter denotes the response to sensing – in this case an inhibitory response to a sensed event.
• The fourth letter refers to ability for rate modulation/programmability; thereby altering pacing rate to meet changing physiological needs such as physical exercise.
• The fifth letter (not present) denotes the presence of an anti- tachycardia function/multi-site pacing.
• Therefore VVIR represents rate-responsive ventricular demand pacing.

Question 6

What are the key considerations for peri-operative care of this patient regarding his pacemaker?

Answer 6

• The patient should be reviewed by a cardiac physiologist on admission for a pacemaker check and to deactivate rate-response, anti-tachycardia and defibrillator functions, if present. It is usually both inappropriate and potentially dangerous to change the mode to a fixed-rate/asynchronous (non-sensing) mode for surgery, but consider this in a patient who is highly dependent on their pacemaker and when electro-magnetic interference during the surgery is likely. A follow-up visit will be required after anaesthesia and surgery to check appropriate functioning of the device and reinstate previous functionality.
• Correct electrolytes prior to induction of anaesthesia.
• Ensure a cardiostable anaesthetic to minimise the risk of perioperative ischaemic events, dysrhythmias and disturbance of pacemaker
  function.
• Ensure immediate access to emergency resuscitation drugs, a defibrillator with pacing functionality, and isoprenaline, in case of pacemaker dysfunction. Place defibrillator/pacing pads before surgery at least 10cm away from the pacemaker box to avoid damage.

Question 7

What are the key considerations for perioperative care of this patient regarding his pacemaker?

Continued…

Answer 7

• Routine AAGBI monitoring is appropriate and will not interfere with pacemaker function, although ensure the ECG display is set to detect pacing spikes. Invasive blood pressure monitoring should be considered for accurate measurement and evidence of reliable electro-mechanical coupling. Care should be taken with central venous catheter insertion to avoid lead displacement.
• Fasciculations associated with suxamethonium and shivering may cause pacemaker dysfunction. Consider using other neuromuscular blocking agents where possible.
• Discuss antibiotic prophylaxis, given the risk of developing pacing lead endocarditis.
• Theatre staff should be made aware of the pacemaker and bipolar diathermy should be used if essential.
• Ensure postoperative recovery in a high dependency environment with continuous monitoring and access to emergency resuscitation equipment.

Question 8

Pacemaker main points:

Answer 8

• PPM indications, model, make, interrogation date, underlying rhythm, dependency, issues
• nomenclature PPM and ICD NB
• CIED indications
• key considerations: cardiac physiologist before and after, de-activate rate-response, anti-tachy and defib modes
• fixed/asynchronous only if highly dependent and interference likely (diathermy)
• have emergency drugs/defib and pacing at the ready (10cm away)
• Cautions with sux/shivering