Chapter 11. Peri -arrest arrhythmias

Peri-arrest arrhythmias refer to rhythm abnormalities occurring before or after cardiac arrest. They fall into two categories:

1. Arrhythmias leading to cardiac arrest – May occur in acute myocardial infarction (AMI), other cardiac conditions, or even in structurally normal hearts. Some require immediate intervention to prevent deterioration.
2. Arrhythmias after resuscitation from cardiac arrest – Indicate ongoing instability with a high risk of recurrence.

Recognising and treating these arrhythmias promptly is critical for preventing deterioration or cardiac arrest recurrence.

Assessment of Peri-Arrest Arrhythmias

All patients with suspected arrhythmias should be assessed using the ABCDE approach:

• Airway
• Breathing
• Circulation
• Disability
• Exposure

 Key Steps in Assessment:
✔ Record a 12-lead ECG as early as possible.
✔ Look for adverse features, including shock, syncope, heart failure, and myocardial ischaemia.
✔ Insert intravenous (IV) access and correct hypoxia (oxygen saturation target: 94-98% or 88-92% in COPD).
✔ Identify whether the arrhythmia is a bradyarrhythmia or tachyarrhythmia, as this determines management.

Adverse Features Indicating Urgent Treatment

 Immediate intervention is required if the patient has:

• Shock – Hypotension (SBP < 90 mmHg), pallor, cold extremities, confusion.
• Syncope – Brief loss of consciousness due to inadequate cerebral perfusion.
• Heart Failure – Pulmonary oedema, raised JVP, peripheral oedema.
• Myocardial Ischaemia – Chest pain and ECG changes suggesting acute coronary syndrome (ACS).

 If adverse features are present → Urgent treatment is required.

Treatment of Peri-Arrest Arrhythmias

Management follows specific treatment algorithms for tachyarrhythmias and bradyarrhythmias.

 Tachyarrhythmias (HR >100 bpm)

Classified as:

• Narrow-complex tachycardia (QRS < 120 ms)
• Broad-complex tachycardia (QRS ≥ 120 ms)

 Treatment for Tachyarrhythmias:
If Adverse Features are Present (Unstable Patient) → Immediate synchronised cardioversion
✔ If unsuccessful, give IV amiodarone (300 mg over 10-20 min), followed by another shock.
✔ If still refractory, continue amiodarone infusion (900 mg over 24 hours).

If No Adverse Features (Stable Patient):
✔ Assess ECG (QRS width and rhythm regularity).
✔ Regular narrow-complex tachycardia → Consider vagal manoeuvres, adenosine 6 mg IV (increase dose if ineffective).
✔ Irregular narrow-complex tachycardia → Likely atrial fibrillation; use rate control (beta-blockers or diltiazem).
✔ Regular broad-complex tachycardia → Assume ventricular tachycardia (VT) and treat with amiodarone.
✔ Irregular broad-complex tachycardia → Consider Torsades de Pointes (TdP) and give IV magnesium sulfate.

 Bradyarrhythmias (HR <60 bpm)

Causes include sinoatrial node disease, AV block, drugs (beta-blockers, digoxin), and metabolic disorders.

🔹 Treatment for Bradyarrhythmias:
If Adverse Features are Present (Unstable Patient)
✔ First-line: Give atropine 500 mcg IV, repeat every 3-5 minutes up to 3 mg.
✔ If atropine is ineffective: Consider transcutaneous pacing or drugs:

• Isoprenaline (5 mcg/min IV infusion)
• Adrenaline (2-10 mcg/min IV infusion)
• Glucagon (if beta-blocker or calcium-channel blocker overdose suspected)
  ✔ If refractory: Transvenous pacing is required.

If No Adverse Features (Stable Patient)
✔ Monitor closely and identify the underlying cause (e.g., drug-induced, metabolic disorder).
✔ Seek expert help if the patient has Mobitz Type II or complete heart block.

 Special Considerations

 Torsades de Pointes (TdP) – Associated with prolonged QT interval.
✔ Give IV magnesium sulfate (2g over 10 min).
✔ Consider overdrive pacing if recurrent.
✔ Avoid QT-prolonging drugs (e.g., amiodarone).

 Pulseless Electrical Activity (PEA) – Any electrical activity without a pulse.
✔ Search for reversible causes (4 H’s & 4 T’s):

• Hypoxia, Hypovolaemia, Hypo-/Hyperkalaemia, Hypothermia
• Tension pneumothorax, Tamponade, Toxins, Thrombosis (MI/PE)
  ✔ Treat underlying cause aggressively.

 Atrial Fibrillation (AF) in ACS
✔ Use beta-blockers or calcium-channel blockers for rate control.
✔ Avoid amiodarone in pre-excited AF (e.g., WPW syndrome).

 Post-Resuscitation Arrhythmias
✔ Common after return of spontaneous circulation (ROSC).
✔ Requires ECG monitoring and cardiology review for potential ICD placement.

 Summary 

✔ Peri-arrest arrhythmias can lead to or follow cardiac arrest and require prompt recognition and treatment.
✔ ABCDE assessment + 12-lead ECG are critical to identify adverse features and initiate appropriate treatment.
✔ Tachyarrhythmias (HR >100 bpm) require cardioversion or anti-arrhythmic drugs, depending on stability and ECG findings.
✔ Bradyarrhythmias (HR <60 bpm) require atropine or pacing if they cause haemodynamic instability.
✔ Reversible causes (e.g., electrolyte imbalance, hypoxia, drug toxicity) must always be considered.
✔ Seek expert help if advanced interventions (transvenous pacing, ICD placement) are required.