Electrical Cardioversion

Quick Reference

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ACEM Exam Focus

What Examiners Expect

Fellowship Written:

• Indications for synchronized cardioversion (stable vs unstable arrhythmias)
• Energy selection for different arrhythmias (AF, flutter, SVT, VT)
• ANZCOR guidelines and algorithm for tachycardia management
• Anticoagulation requirements before and after cardioversion
• Electrode placement techniques and comparative effectiveness
• Sedation options, dosing, and monitoring requirements
• Post-cardioversion monitoring and disposition
• Complication recognition and management

Fellowship OSCE:

• Consent and explanation of procedure including risks/benefits
• Correct patient preparation (fasting status, IV access, sedation choice)
• Equipment check (defibrillator functionality, SYNC mode, energy selection)
• Correct electrode placement and skin preparation
• Synchronization confirmation (QRS complex triggering)
• Team communication during cardioversion
• Post-cardioversion assessment and monitoring

Fellowship Viva:

• Clinical decision-making: cardioversion vs medical management vs rate control
• Energy selection rationale for different arrhythmias
• Anticoagulation strategy based on AF duration and stroke risk
• Management of failed cardioversion or early recurrence
• Complication management (asystole, VF, stroke, burns)
• Indigenous health considerations (cultural safety, family involvement)
• Remote/rural considerations (retrieval timing, equipment limitations)

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Key Points

1. ALWAYS press SYNC button before cardioversion - asynchronous shock in R-on-T can precipitate ventricular fibrillation (PMID: 6306761)

2. Energy selection matters: AF 120-200J biphasic, flutter 50J biphasic, SVT 50-100J biphasic, monomorphic VT 120-200J biphasic (PMID: 16243205, 17008444)

3. Anticoagulation mandatory for AF greater than 48 hours or unknown duration: 3 weeks therapeutic anticoagulation before cardioversion OR TEE to exclude thrombus, minimum 4 weeks anticoagulation after (PMID: 10804075, 15358670)

4. Anteroposterior electrode placement (one anterior over right sternal border, one posterior left scapula) may be superior to anterolateral for AF cardioversion, especially in obesity (PMID: 16308363, 18427145)

5. Remove oxygen sources for at least 1 meter before shock to prevent fire, ensure skin is dry and shaved hair, conductive gel applied adequately (PMID: 17976465)

6. Post-cardioversion atrial stunning occurs for up to 4 weeks, maintaining thromboembolic risk despite sinus rhythm - continue anticoagulation (PMID: 9549945, 12783797)

7. Sedation options: Propofol (1-1.5 mg/kg) - rapid onset, short duration; Midazolam (0.05-0.1 mg/kg) - slower onset, amnesic; combination provides sedation + analgesia (fentanyl 50-100 mcg) (PMID: 15572125, 16330752)

8. Contraindications: Digoxin toxicity (risk of ventricular fibrillation), unstable digoxin level without adequate anticoagulation for AF greater than 48h, patient refusal, severe hypokalaemia, hypomagnesaemia (PMID: 6306761)

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Indications

Absolute Indications (Emergency Cardioversion)

Specific Arrhythmias Requiring Immediate Cardioversion:

• Atrial fibrillation with rapid ventricular response causing instability
• Atrial flutter with 1:1 conduction
• SVT causing haemodynamic compromise
• Monomorphic VT with pulse
• Polymorphic VT (but usually requires defibrillation)

Relative Indications (Elective/Procedure Cardioversion)

Stable but symptomatic arrhythmias:

• New-onset atrial fibrillation below 48 hours - symptomatic
• Atrial flutter symptomatic despite rate control
• SVT refractory to vagal manoeuvres or adenosine
• Recurrent symptomatic AF for rhythm control strategy

Elective cardioversion should be performed with:

• Adequate anticoagulation (if AF greater than 48h or unknown duration)
• TEE to exclude thrombus if not anticoagulated for 3 weeks
• Fasting status appropriate for sedation (usually 4-6 hours)
• Monitoring equipment available

When to Consider

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Contraindications

Absolute Contraindications

Relative Contraindications

• Digoxin without adequate anticoagulation for AF greater than 48 hours - increased thromboembolic risk
• Severe structural heart disease: severe aortic stenosis, hypertrophic obstructive cardiomyopathy (may cause haemodynamic deterioration)
• Recent thromboembolic event (below 3 months) - high recurrence risk
• Severe COPD - may not tolerate supine position or sedation
• Pregnancy - teratogenicity concerns with medications, consider deferral to trimester 2
• Known proarrhythmic conditions: long QT syndrome, Brugada syndrome

Risk-Benefit Considerations

When relative contraindications may be acceptable:

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Equipment

Essential Equipment

Optional Equipment

Equipment Sizing

Adult Pads

Paediatric

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Preparation

Patient Preparation

1. Assessment:

   • Confirm arrhythmia diagnosis on ECG (12-lead and rhythm strip)
   • Assess haemodynamic stability (BP, level of consciousness, signs of shock)
   • Determine indication (emergency vs elective)
   • Review anticoagulation status and AF duration
   • Check medication history (digoxin, antiarrhythmics)
   • Assess fasting status for elective cardioversion

2. Consent:

   • Explain procedure, risks (stroke, arrhythmias, sedation, burns), benefits, alternatives
   • Document consent in medical record
   • For emergency cardioversion, proceed with implied consent if patient incapacitated

3. Positioning:

   • Supine position on firm surface
   • Remove jewellery, necklaces, metal objects
   • Ensure adequate access to chest and back (if anteroposterior placement)
   • Consider 15-30° head elevation if respiratory compromise

4. IV Access:

   • Secure large-bore IV (18G preferred)
   • Second IV recommended if possible
   • Ensure access tested and patent

5. Monitoring:

   • Continuous ECG monitoring
   • Pulse oximetry
   • Non-invasive blood pressure (q1-2 minutes during procedure)
   • Capnography if available during sedation

6. Sedation Preparation (for elective cardioversion):

   • Verify NPO status (4-6 hours for solids, 2 hours for clear fluids)
   • Prepare sedation medications
   • Have reversal agents available (naloxone, flumazenil)
   • Suction equipment ready

7. Oxygen Preparation:

   • Pre-oxygenate with 100% via non-rebreather mask before sedation
   • CRITICAL: Remove oxygen mask and move tubing greater than 1 meter away before shock
   • Have staff hold tubing away from chest during shock

Operator Preparation

1. Standard precautions: PPE (gloves, gown, eye protection)
2. Hand hygiene before patient contact
3. Equipment check:
   • Verify defibrillator battery charged
   • Test SYNC function with rhythm strip
   • Confirm energy selection appropriate
   • Check pad expiration dates
4. Assistance arranged:
   • At least one additional staff member to assist
   • Roles assigned: medication administration, airway management, defibrillator operation
5. Backup plan identified:
   • What to do if cardioversion fails
   • Arrangement for admission if indicated
   • Cardiology consultation available if needed

Site Preparation

1. Skin preparation:
   • Shave dense hair at electrode sites if needed
   • Clean skin with alcohol swabs and allow to dry completely
   • CRITICAL: Ensure skin is completely dry before applying pads
2. Electrode application:
   • Apply generous conductive gel to pads
   • Press pads firmly to ensure good skin contact
   • Remove air bubbles between pad and skin
3. Positioning:
   • Place electrodes according to chosen technique (see below)
   • Ensure electrodes are at least 10-15cm apart
   • Avoid placement over implanted devices (pacemakers, ICDs) if possible

Electrode Placement Options

Anterolateral Placement (Most Common)

Advantages:

• Easier to apply with patient supine
• Allows rapid access for CPR if needed
• Standard placement most staff familiar with

Disadvantages:

• Lower success rate for AF compared to anteroposterior
• May be less effective in obese patients

Anteroposterior Placement (Alternative)

Advantages:

• Higher success rates for AF cardioversion (PMID: 16308363, 18427145)
• Better vector through atria for AF conversion
• More effective in obese patients

Disadvantages:

• Requires moving patient to position posterior pad
• More difficult during CPR if needed
• Less familiar to many operators

Decision Algorithm:

• First attempt: Anterolateral (familiarity, speed)
• Failed first attempt: Switch to anteroposterior
• Obese patient: Consider anteroposterior first
• Operator familiarity: Choose technique most confident with

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Procedure Steps

Step-by-Step Technique

Step 1: Verify Indications and Preparation

Actions:

• Confirm diagnosis and arrhythmia type on 12-lead ECG
• Assess haemodynamic stability
• Verify anticoagulation status (if AF greater than 48h)
• Check for contraindications (digoxin toxicity, electrolyte disturbances)
• Ensure appropriate equipment available
• Confirm patient consent

Key Point: For unstable arrhythmias, proceed immediately without delay for additional investigations

Common Error: Proceeding with cardioversion without confirming rhythm - treat the wrong arrhythmia

Step 2: Apply Monitoring and IV Access

Actions:

• Connect patient to cardiac monitor with rhythm display
• Attach pulse oximetry and NIBP
• Secure IV access (18G or larger preferred)
• Set up continuous BP monitoring if available
• Verify ECG leads are correctly connected

Key Point: Ensure ECG leads are NOT placed over electrode sites as this can cause burns

Common Error: Placing ECG electrodes where they interfere with defibrillation pad placement

Step 3: Choose Electrode Placement and Apply Pads

Actions:

• Choose anterolateral or anteroposterior placement based on clinical factors
• Shave and clean skin at electrode sites
• Allow skin to dry completely
• Apply conductive gel generously
• Press electrodes firmly to ensure good contact
• Remove any air bubbles between pad and skin

Key Point: Firm pressure on pads for 10-15 seconds after application improves conductivity and reduces impedance

Common Error: Inadequate gel or poor contact causing high impedance and failed cardioversion

Step 4: Connect Defibrillator and Set Energy

Actions:

• Connect electrode cables to defibrillator
• Select biphasic mode (monophasic if biphasic unavailable)
• Set initial energy based on arrhythmia type:
  • "Atrial fibrillation: 120-200J biphasic"
  • "Atrial flutter: 50J biphasic"
  • "Supraventricular tachycardia: 50-100J biphasic"
  • "Monomorphic VT with pulse: 120-200J biphasic"

Key Point: Start with lower energy (AF 120J, flutter 50J) and increase if first attempt fails

Common Error: Using maximum energy for first attempt - not necessary and increases discomfort

Step 5: Synchronize Defibrillator

CRITICAL STEP:

1. Press SYNC button on defibrillator
2. Look for synchronization markers on ECG display (usually small markers or dots on QRS complexes)
3. Verify sync markers are correctly tracking the R-wave (not the T-wave)
4. Ensure rhythm is being detected correctly

Key Point: If patient moves or rhythm becomes unstable, the sync may be lost - verify sync is still active before each shock

Common Error: Failing to press SYNC button - shock delivered asynchronously, potentially fatal

Step 6: Administer Sedation (for Elective Cardioversion)

For Emergency Cardioversion (unstable patient):

• Proceed WITHOUT sedation if patient unstable
• Use analgesia only if time permits and patient can receive it

For Elective Cardioversion (stable patient): Propofol (Preferred):

• Dose: 1-1.5 mg/kg IV bolus (average 70-100 mg)
• Onset: 15-30 seconds
• Duration: 5-10 minutes
• Advantages: Rapid onset, short duration, amnestic
• Disadvantages: Hypotension, respiratory depression (PMID: 15572125)

Midazolam:

• Dose: 0.05-0.1 mg/kg IV bolus (average 3-5 mg)
• Onset: 2-3 minutes
• Duration: 30-60 minutes
• Advantages: Amnestic, less hypotension
• Disadvantages: Slower onset, longer duration

Combination (Sedation + Analgesia):

• Midazolam 0.02-0.05 mg/kg + Fentanyl 50-100 mcg IV
• Advantages: Synergistic effect, patient comfort
• Disadvantages: Higher risk of respiratory depression

Key Point: Titrate sedation to effect - patient should be unresponsive but maintaining spontaneous respiration

Common Error: Over-sedation causing apnea and hypotension - be prepared to support airway and ventilation

Step 7: Prepare Team and Patient for Shock

Actions:

• Announce to team: "Charging to [energy] joules"
• Ensure all team members clear of patient and bed
• Remove oxygen mask and tubing at least 1 meter away from chest
• Verify no one touching patient or bed
• Confirm SYNC is active and markers correctly tracking R-wave
• Announce: "Charging, stand clear"

Key Point: Ensure oxygen is well away from chest - oxygen-enriched environment + spark = fire

Common Error: Not removing oxygen tubing before shock - potential for fire/explosion

Step 8: Deliver Shock

Actions:

1. Defibrillator announces charging complete
2. Announce: "Everyone clear, shocking NOW"
3. Verify no one touching patient or bed
4. Press and hold shock buttons simultaneously (or single button on newer devices)
5. Watch for patient movement (muscle contraction)
6. Observe ECG for rhythm change

Key Point: Maintain contact with shock buttons until energy is fully delivered

Common Error: Releasing shock button too early - incomplete energy delivery

Step 9: Post-Shock Assessment

Actions:

• Immediately assess cardiac rhythm on monitor
• Check pulse and blood pressure
• Assess level of consciousness (if sedated)
• If sinus rhythm restored: monitor for recurrence
• If arrhythmia persists: consider higher energy, different pad placement, or alternative therapy

Key Point: If patient remains in arrhythmia, repeat cardioversion with higher energy or different technique

Common Error: Not checking pulse after shock - patient may be in asystole or profound bradycardia

Step 10: Post-Cardioversion Monitoring

Immediate (First 30 minutes):

• Continuous ECG monitoring
• Blood pressure q5 minutes x3, then q15 minutes
• Pulse oximetry
• Level of consciousness monitoring
• Observe for arrhythmia recurrence

Ongoing (Next 4 hours):

• Continue cardiac monitoring
• Document sedation recovery
• Assess for complications
• Consider need for admission or observation
• Discharge planning if appropriate

Key Point: Atrial stunning maintains thromboembolic risk for up to 4 weeks - continue anticoagulation regardless of sinus rhythm (PMID: 9549945, 12783797)

Common Error: Stopping anticoagulation after successful cardioversion - patient remains at stroke risk

Energy Selection Algorithm

Atrial Fibrillation

Evidence: Biphasic waveforms have superior efficacy compared to monophasic for AF cardioversion, with lower energy requirements (PMID: 16243205, 17008444)

Atrial Flutter

Evidence: Flutter requires lower energy than AF due to more organized rhythm and smaller critical mass (PMID: 16243205)

Supraventricular Tachycardia (SVT)

Note: SVT often responds to vagal manoeuvres or adenosine first - cardioversion reserved for refractory or unstable SVT

Ventricular Tachycardia (Monomorphic with Pulse)

Evidence: Monomorphic VT responds well to synchronized cardioversion; polymorphic VT requires immediate defibrillation (PMID: 17008444)

Confirmation of Success

Note: Transient bradycardia may occur after successful cardioversion - usually resolves within minutes

Securing/Completion

Post-Procedure Documentation:

1. Indication for cardioversion
2. Arrhythmia type confirmed
3. Energy used for each shock attempt
4. Number of shocks delivered
5. Electrode placement used
6. Sedation administered and doses
7. Outcome (sinus rhythm restored or persistent arrhythmia)
8. Complications (none, specific complications if occurred)
9. Post-cardioversion rhythm
10. Disposition (admission, discharge, observation)

Disposition:

• Successful cardioversion, low risk, stable: May consider discharge after 4-hour observation
• Failed cardioversion or high-risk features: Admit for observation, cardiology review
• Complications during procedure: Admit to appropriate level of care (ward, HDU, ICU)

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Ultrasound Guidance

When to Use

• Difficult IV access (ultrasound-guided peripheral or central line)
• Assess cardiac function pre-cardioversion (LV function, pericardial effusion, valvular disease)
• Guide electrode placement in challenging anatomy (pectus excavatum, thoracic deformities)
• Post-cardioversion assessment of ventricular function

Probe Selection

Technique

Cardiac Assessment Before Cardioversion:

1. Obtain subcostal 4-chamber view
2. Assess left ventricular function (hyperdynamic vs depressed)
3. Look for pericardial effusion
4. Assess valvular disease (particularly mitral stenosis)
5. Estimate left atrial size if possible

Post-Cardioversion Assessment:

1. Verify ventricular function maintained
2. Assess for new wall motion abnormalities (suggestive of coronary embolism)
3. Confirm sinus rhythm (if in doubt on ECG)

Sonographic Anatomy

Normal Sinus Rhythm:

• Regular atrial contractions
• A-V synchrony
• Normal ventricular function

Atrial Fibrillation:

• No discernible atrial contraction
• "Irregularly irregular" ventricular contractions
• Loss of A-V synchrony

Atrial Flutter:

• Sawtooth appearance to atrial contractions
• Often 2:1, 3:1, or 4:1 AV block
• Regular ventricular rhythm (constant block ratio)

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Alternative Techniques

Internal Cardioversion

When to use:

• Failed external cardioversion (multiple attempts with maximum energy)
• Elective cardioversion in cardiac catheterisation laboratory setting
• Patients with high impedance (obesity, chronic lung disease)

Advantages:

• Higher success rates (90-95% for refractory AF)
• Lower energy required (lower risk of burns)
• Can be performed under conscious sedation

Disadvantages:

• Invasive procedure (requires venous access and electrode placement in heart)
• Requires cardiac electrophysiology lab
• Higher risk of complications (vascular, cardiac)
• Not available in most EDs

Technique:

• Insert catheters via femoral vein under fluoroscopy
• Position electrodes in right atrium and coronary sinus
• Deliver low-energy internal shocks (typically 1-10J)
• Perform under conscious sedation

Pharmacological Cardioversion

When to use:

• Stable patients without haemodynamic compromise
• Patients with contraindications to electrical cardioversion
• As adjunct to electrical cardioversion (facilitates success)

Agents:

Advantages:

• Non-invasive, can be performed on ward or outpatient
• No sedation required for most agents
• Lower complication profile (if appropriate patient selection)

Disadvantages:

• Slower onset than electrical cardioversion
• Proarrhythmic risk (torsades de pointes, 1:1 flutter)
• Contraindicated in significant structural heart disease (except amiodarone)
• Lower success rates for long-standing AF

Patient Selection for Pharmacological Cardioversion:

• No significant structural heart disease (flecainide, propafenone)
• Normal QT interval (flecainide, propafenone, sotalol, ibutilide)
• No severe LV dysfunction (avoid flecainide, propafenone)
• No prior VT/VF (avoid most agents except amiodarone)
• Normal potassium and magnesium levels

Hybrid Approach (Pharmacological + Electrical)

When to use:

• High likelihood of electrical cardioversion failure (obesity, chronic lung disease)
• Failed first electrical cardioversion attempt

Technique:

1. Administer antiarrhythmic agent (e.g., amiodarone 300mg IV over 30 minutes)
2. Wait 30-60 minutes for drug effect
3. Proceed with electrical cardioversion at standard or reduced energy

Advantages:

• Lower energy requirements
• Higher success rates
• Reduced recurrence of AF

Disadvantages:

• Requires medication administration
• Slower than immediate electrical cardioversion
• Adds pharmacological risks

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Paediatric Considerations

Age-Specific Modifications

Equipment Sizing

Paediatric Electrodes:

• Use paediatric pads for children below 25kg
• Use adult paddles/pads for children greater than 25kg
• Ensure electrodes are appropriate size (not overlapping)

Airway Equipment:

• Size-appropriate bag-valve-mask device
• Age-appropriate oropharyngeal airway
• Suction catheters of appropriate size

Technique Modifications

Differences in Children vs Adults:

1. Lower energy requirements: Children require lower energy (J/kg) compared to fixed adult doses
2. Smaller thorax: Electrodes may need to be placed closer (but maintain 10cm distance)
3. Airway prioritisation: Children desaturate faster - secure airway before sedation
4. Temperature regulation: Children lose heat faster - maintain normothermia
5. Sedation: Children often require deeper sedation for cardioversion
6. Arrhythmia types: SVT is more common in children than AF/flutter

Common Paediatric Arrhythmias Requiring Cardioversion:

• Supraventricular tachycardia (most common)
• Atrial flutter (congenital heart disease, postoperative)
• Ventricular tachycardia (structural heart disease, electrolyte disturbances)
• Atrial fibrillation (rare in children, usually associated with structural disease)

Special Considerations:

• Congenital heart disease: Cardiology consultation mandatory
• Postoperative cardiac surgery: Consider internal cardioversion, pacemaker dependency
• Channelopathies (long QT, Brugada): Avoid proarrhythmic agents, consider expert consultation

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Complications

Immediate Complications

Delayed Complications

Complication Prevention

Skin Burns:

• Ensure skin is dry before electrode application
• Apply adequate conductive gel
• Remove excess gel between shocks
• Use appropriate pad size for patient
• Rotate pad sites if multiple cardioversions needed

Thromboembolism:

• Appropriate anticoagulation based on AF duration and stroke risk (PMID: 10804075, 15358670)
• TEE to exclude thrombus if not anticoagulated 3 weeks (PMID: 9566970)
• Continue anticoagulation minimum 4 weeks post-cardioversion (PMID: 9549945, 12783797)
• Consider early cardioversion (below 48h AF) to reduce thrombus formation

Arrhythmias:

• Verify SYNC is active before each shock (PMID: 6306761)
• Correct electrolyte abnormalities before cardioversion
• Avoid in digoxin toxicity
• Use appropriate energy for arrhythmia type
• Monitor continuously for arrhythmia recurrence

Sedation Complications:

• Use appropriate sedative agent and dose
• Monitor airway, breathing, circulation continuously
• Have reversal agents available
• Ensure NPO status for elective cardioversion
• Consider capnography for respiratory monitoring

Hypotension:

• IV access before sedation
• IV fluids ready
• Monitor blood pressure frequently
• Consider lower sedation dose if patient volume-depleted
• Have vasopressors available (metaraminol, phenylephrine)

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Troubleshooting

Rescue Techniques

If First Cardioversion Fails:

1. Increase energy (AF: 120J → 200J → maximum)
2. Change electrode placement (anterolateral → anteroposterior)
3. Consider pharmacologic cardioversion (amiodarone 300mg IV)
4. Wait 10-15 minutes and repeat
5. Consider internal cardioversion (cardiology consultation)

If Patient Remains Unstable After Cardioversion:

1. Assess airway, breathing, circulation
2. Verify sinus rhythm on monitor
3. Check blood pressure and perfusion
4. Consider alternative diagnoses (sepsis, PE, haemorrhage)
5. Obtain urgent echocardiogram
6. ICU admission, cardiology consultation

If Ventricular Arrhythmias Occur:

1. Ventricular fibrillation: Immediate defibrillation (unsynchronized), ACLS protocol
2. Ventricular tachycardia: Assess pulse, treat per ACLS (sync cardioversion if with pulse, defibrillation if pulseless)
3. Torsades de pointes: Magnesium sulfate 2g IV over 10 minutes, consider overdrive pacing

If Stroke Suspected Post-Cardioversion:

1. Immediate assessment using FAST (Face, Arms, Speech, Time)
2. Urgent CT brain (non-contrast)
3. Activate stroke team
4. Consider thrombolysis or thrombectomy if within window
5. Anticoagulation (unless contraindicated)

If Patient Cannot Be Sedated (e.g., full stomach):

1. Emergency cardioversion without sedation if unstable
2. Consider rapid sequence intubation with cricoid pressure
3. Discuss risks/benefits with patient
4. Consider pharmacologic cardioversion (if time permits and appropriate)

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Post-Procedure Care

Immediate Care

1. Airway and Breathing:

   • Maintain airway until fully awake from sedation
   • Monitor oxygen saturation continuously
   • Supplemental oxygen if SpO2 below 94% or on room air baseline
   • Encourage deep breathing and coughing

2. Circulation:

   • Continuous cardiac monitoring for at least 4 hours
   • Blood pressure q5 minutes x3, then q15 minutes until stable
   • IV access maintained until stable
   • Monitor for arrhythmia recurrence

3. Neurological:

   • Assess level of consciousness regularly
   • Monitor for stroke symptoms (FAST assessment)
   • Document Glasgow Coma Scale pre- and post-procedure

4. Patient Comfort:

   • Provide analgesia for any discomfort (paracetamol, opioids if needed)
   • Explain procedure outcome to patient and family
   • Reassure patient about sedation recovery

5. Documentation:

   • Procedure details (indication, energy used, number of shocks, outcome)
   • Medications administered (sedation, antiarrhythmics)
   • Complications (if any)
   • Post-procedure status (rhythm, blood pressure, neurological status)
   • Disposition plan

Monitoring

Additional Monitoring (if indicated):

• Cardiac biomarkers (troponin) if chest pain or ischaemic ECG changes
• Echocardiogram if haemodynamic instability or suspected complications
• Serum electrolytes (K+, Mg2+) if arrhythmia recurrence
• Digoxin level if on digoxin therapy

Imaging Confirmation

Indications for Imaging:

• Chest pain or ischaemic ECG changes → CXR, consider CT coronary angiogram
• Suspected stroke → Urgent CT brain
• Suspected cardiac injury → CXR, echocardiogram
• Suspected pneumothorax (rare, from rib fracture during CPR) → CXR

Routine Imaging:

• Generally NOT required for uncomplicated cardioversion
• Consider baseline CXR if significant cardiac disease or post-CPR

Disposition

Admission Criteria:

• Failed cardioversion
• Recurrence of arrhythmia within 4 hours
• Haemodynamic instability
• Significant cardiac disease (recent MI, severe LV dysfunction, valvular disease)
• Anticoagulation not yet therapeutic (if AF greater than 48h)
• High CHA₂DS₂-VASc score (greater than 2)
• No home support or unable to follow instructions
• Complications during or after procedure

Discharge Criteria (all must be met):

• Successful cardioversion with stable sinus rhythm for ≥4 hours
• Haemodynamically stable (SBP greater than 90 mmHg, no symptoms)
• Fully recovered from sedation (back to baseline)
• Adequate anticoagulation plan in place
• Follow-up arranged (cardiology clinic within 1-2 weeks)
• Patient understands warning signs (palpitations, chest pain, stroke symptoms)
• Responsible adult to accompany patient home
• No complications

Follow-up Requirements:

• Cardiology review within 1-2 weeks
• ECG at follow-up
• Consider 24-48 hour Holter monitor
• Review anticoagulation strategy (duration, ongoing need)
• Consider long-term antiarrhythmic therapy for rhythm control

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OSCE Practice

OSCE Station 1: Electrical Cardioversion Procedure

Setting: ED resuscitation bay Time: 11 minutes Task: You are the FACEM overseeing electrical cardioversion for a 65-year-old with new-onset atrial fibrillation, rate 160 bpm, blood pressure 95/60 mmHg, patient is symptomatic but stable. Perform the procedure.

Examiner Instructions:

• Observe candidate's systematic approach
• Assess technical proficiency
• Evaluate team leadership and communication
• Monitor for critical errors (especially SYNC button)

Candidate Instructions:

A 65-year-old male presents with palpitations and shortness of breath for 4 hours. ECG shows new-onset atrial fibrillation with rapid ventricular response, rate 160 bpm. Blood pressure is 95/60 mmHg, heart rate 160 bpm, respiratory rate 20/min, SpO2 94% on room air. Patient is alert but feels dizzy. You have decided to perform electrical cardioversion. Please demonstrate the procedure.

Equipment Provided:

• Defibrillator with adult pads (biphasic, SYNC capable)
• ECG monitor
• IV access (18G in left antecubital fossa)
• Sedation: Propofol 10mg/mL (20mL vial)
• Emergency drugs (atropine, adrenaline, amiodarone)
• Oxygen equipment
• Suction

Marking Criteria:

Common Pitfalls:

• Forgetting to press SYNC button (critical)
• Not verifying sync markers on R-wave (risk of R-on-T)
• Using excessive energy for first attempt (start 120J for AF)
• Forgetting to remove oxygen before shock (fire risk)
• Not checking for contraindications (digoxin, anticoagulation status)
• Inadequate skin preparation (wet skin causes burns)
• Poor team communication (clear team before shock)
• Not monitoring patient after shock (may have complications)

Pass Standard: 18/25 (72%) with no critical failures

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OSCE Station 2: Cardioversion Decision-Making and Management

Setting: ED consultation room Time: 11 minutes Task: Discuss the management of a 72-year-old with persistent atrial fibrillation and plan for elective cardioversion.

Examiner Instructions:

• Assess clinical decision-making
• Evaluate knowledge of anticoagulation requirements
• Assess understanding of risks/benefits
• Monitor for missed critical points (anticoagulation, contraindications)

Candidate Instructions:

A 72-year-old woman has known atrial fibrillation for 3 months. She is rate-controlled with metoprolol but remains symptomatic with fatigue and reduced exercise tolerance. Her CHA₂DS₂-VASc score is 4 (age 72, hypertension, diabetes, previous TIA). She is currently on warfarin, INR 2.5. The cardiologist is considering electrical cardioversion. Please discuss your approach.

Information Available (if candidate asks):

• Current medication: Warfarin 5mg daily (INR 2.5), metoprolol 50mg BD
• Echocardiogram: LV EF 55%, mild left atrial enlargement, no valvular disease
• No contraindications to cardioversion
• Patient understands procedure and willing to proceed

Marking Criteria:

Common Pitfalls:

• Missing anticoagulation requirements (critical)
• Not understanding atrial stunning (stroke risk persists post-CV)
• Not checking contraindications (digoxin, recent stroke)
• Incorrect energy selection (too low or too high)
• Not considering patient preferences and goals of care
• Not planning for long-term anticoagulation
• Not recognising high CHA₂DS₂-VASc score (4 = high risk)

Pass Standard: 14/20 (70%) with no critical failures

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OSCE Station 3: Complications Management

Setting: ED resuscitation bay Time: 11 minutes Task: You have just performed electrical cardioversion on a 58-year-old with atrial fibrillation. Immediately post-shock, the patient develops complications. Manage the situation.

Examiner Instructions:

• Simulate patient developing complications after cardioversion
• Assess immediate recognition and management
• Evaluate team leadership under pressure
• Monitor for appropriate management of specific complications

Candidate Instructions:

You have just performed electrical cardioversion on a 58-year-old male with atrial fibrillation. Energy used was 200J biphasic. Immediately after the shock, the following occurs: The patient's blood pressure drops to 70/40 mmHg, heart rate is 40 bpm, and he appears drowsy. The monitor shows sinus bradycardia with intermittent pauses up to 4 seconds. Please manage this patient.

Equipment Provided:

• Defibrillator/monitor
• Emergency drugs (atropine, adrenaline, isoprenaline)
• IV access functional
• Transcutaneous pacer available
• Intubation equipment

Marking Criteria:

Alternative Complication (Examiner may use):

• Ventricular fibrillation: Immediate recognition, defibrillation, ACLS
• Stroke symptoms: FAST assessment, CT brain, stroke activation
• Asystole: CPR, epinephrine, consider causes

Common Pitfalls:

• Delay in recognising bradycardia
• Under-dosing atropine (need 0.5mg, may repeat to 3mg)
• Not preparing pacing equipment early
• Forgetting to check for reversible causes
• Poor team communication
• Not escalating to cardiology

Pass Standard: 13/19 (68%) with no critical failures

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Viva Questions

Viva Question 1: Indications and Contraindications

Question: "A 52-year-old presents with palpitations and shortness of breath for 6 hours. ECG shows atrial fibrillation with rapid ventricular response, rate 165 bpm. Blood pressure is 100/70 mmHg, patient is alert and anxious. Discuss your management approach including whether you would cardiovert this patient and the key considerations."

Model Answer:

Initial Assessment:

• Confirm diagnosis of atrial fibrillation on 12-lead ECG
• Assess haemodynamic stability (BP 100/70, alert = stable)
• Determine duration of AF (patient says 6 hours - new onset)
• Assess for complications (chest pain, heart failure symptoms, neurological deficits)

Indications for Cardioversion:

• Stable patient: Rate control or rhythm control strategies both reasonable
• Symptomatic patient (dyspnoea, palpitations): Cardioversion reasonable for symptom relief
• AF below 48 hours: Lower thromboembolic risk, can cardiovert without 3 weeks anticoagulation

My Decision:

• Since patient is haemodynamically stable, I would consider rate control first (beta-blocker or calcium channel blocker)
• If symptoms persist or patient prefers rhythm control, would proceed with electrical cardioversion

Key Considerations Before Cardioversion:

1. Anticoagulation:

   • AF below 48 hours: Can cardiovert without 3 weeks anticoagulation
   • Start anticoagulation (heparin or DOAC) immediately before or after cardioversion
   • Continue anticoagulation for 4 weeks post-cardioversion (atrial stunning)
   • Consider long-term anticoagulation based on CHA₂DS₂-VASc score

2. Contraindications check:

   • Digoxin toxicity: Ask about digoxin use, check symptoms (nausea, visual changes)
   • Electrolyte abnormalities: Check K+, Mg2+
   • Severe structural heart disease: Consider echo if concern
   • Patient consent: Explain risks and benefits

3. Energy selection:

   • Start with 120-200J biphasic for atrial fibrillation
   • May start lower (120J) and increase if needed

4. Electrode placement:

   • Anterolateral (standard) or anteroposterior (higher success in AF, especially obese)

5. Sedation:

   • Verify NPO status (4-6 hours for solids, 2 hours for clear fluids)
   • Propofol 1-1.5 mg/kg IV (rapid onset, short duration)
   • Ensure IV access, monitoring, airway support available

Post-Cardioversion Management:

• Monitor for 4 hours minimum
• Check anticoagulation plan
• Cardiology follow-up
• Consider long-term rhythm control vs rate control

Follow-up: "Would you rate control instead of cardiovert?"

• Yes, reasonable alternative in stable patient
• Metoprolol 5mg IV or diltiazem 0.25mg/kg IV for rate control
• Discuss benefits/risks with patient

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Viva Question 2: Energy Selection and Technique

Question: "Discuss the principles of energy selection for electrical cardioversion of different tachyarrhythmias, and explain the factors that influence success rates of cardioversion."

Model Answer:

Energy Selection by Arrhythmia Type:

1. Atrial Fibrillation:

   • Initial: 120-200J biphasic
   • If first attempt fails: Increase to maximum biphasic energy (200J+)
   • Evidence: Biphasic waveforms superior to monophasic, lower energy required (PMID: 16243205, 17008444)

2. Atrial Flutter:

   • Initial: 50J biphasic
   • If first attempt fails: 100J biphasic
   • Rationale: More organised rhythm, smaller critical mass, lower energy needed

3. Supraventricular Tachycardia (AVNRT, AVRT):

   • Initial: 50-100J biphasic
   • Note: Usually vagal manoeuvres or adenosine first, cardioversion for refractory/unstable

4. Monomorphic Ventricular Tachycardia (with pulse):

   • Stable: 100-150J biphasic
   • Unstable: 150-200J biphasic
   • If fails: Maximum biphasic energy
   • Note: Must be SYNCHRONIZED

5. Polymorphic VT:

   • Treat as cardiac arrest (unsynchronized defibrillation)
   • Not synchronized cardioversion

Biphasic vs Monophasic Waveforms:

• Biphasic: Two-phase current, superior efficacy, lower energy requirements, less myocardial injury
• Monophasic: Older technology, higher energy required, more myocardial injury
• Evidence: Biphasic cardioversion more effective for AF with lower energy (PMID: 16243205)

Factors Influencing Success Rates:

1. Arrhythmia duration:

   • New-onset AF (below 48h): Higher success (80-90%)
   • Persistent AF (greater than 7 days): Lower success (50-70%)
   • Chronic AF (greater than 1 year): Low success (20-30%)

2. Energy selection:

   • Higher energy = higher success (but not linear)
   • Biphasic waveforms superior to monophasic

3. Electrode placement:

   • Anteroposterior: Higher success for AF, especially obesity (PMID: 16308363, 18427145)
   • Anterolateral: Standard, familiar, easier to apply

4. Patient characteristics:

   • Obesity: Lower success due to higher impedance
   • Chronic lung disease: Lower success (hyperinflated lungs)
   • Left atrial size: Larger LA = lower success
   • Structural heart disease: Lower success

5. Antiarrhythmic pre-treatment:

   • Amiodarone 300mg IV increases success rates
   • Ibutilide improves conversion rates, especially for flutter

6. Electrode characteristics:

   • Adequate conductive gel
   • Good skin contact (firm pressure)
   • Appropriate pad size
   • Dry skin before application

7. Defibrillator technology:

   • Biphasic waveforms superior to monophasic
   • Lower impedance = better energy delivery

Follow-up: "How would you manage a patient who fails cardioversion after 3 attempts with maximum energy?"

• Consider pharmacologic cardioversion (amiodarone, flecainide if no structural disease)
• Consider switching electrode placement (anterolateral → anteroposterior)
• Consider internal cardioversion (cardiology consultation)
• Accept rhythm control strategy (rate control + anticoagulation)
• Consider underlying causes (thyroid, alcohol, infection, structural disease)

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Viva Question 3: Anticoagulation and Thromboembolism Risk

Question: "A 68-year-old male presents with atrial fibrillation of unknown duration, estimated 1-2 weeks based on last known sinus rhythm on ECG 3 weeks ago. He is haemodynamically stable. He is not on anticoagulation. Discuss the anticoagulation strategy before, during, and after cardioversion."

Model Answer:

Initial Assessment:

• AF unknown duration, but likely greater than 48 hours (high risk of thrombus)
• Not on anticoagulation (high risk of thromboembolism if cardioverted)
• CHA₂DS₂-VASc: Age 68 (1 point), assume no other risk factors = moderate risk
• Cannot proceed with immediate cardioversion without addressing thromboembolic risk

Two Strategies for Anticoagulation Before Cardioversion:

Strategy 1: 3 Weeks Therapeutic Anticoagulation Before Cardioversion

• Start warfarin (INR target 2.0-3.0) OR DOAC (apixaban, rivaroxaban, dabigatran, edoxaban)
• Continue for minimum 3 weeks
• Verify therapeutic levels (INR 2.0-3.0 for warfarin, or compliance for DOAC)
• Proceed with cardioversion after 3 weeks if INR therapeutic
• Continue anticoagulation for minimum 4 weeks post-cardioversion

Strategy 2: TEE-Guided Cardioversion

• Perform transesophageal echocardiogram to exclude left atrial appendage thrombus
• If NO thrombus: Start anticoagulation immediately, cardiovert same day
• If thrombus present: Delay cardioversion, anticoagulate for 3+ months, repeat TEE
• Continue anticoagulation for minimum 4 weeks post-cardioversion (PMID: 9566970)

Evidence:

• Thromboembolic risk after cardioversion: 0.5-1.5% without adequate anticoagulation (PMID: 10804075)
• 3 weeks anticoagulation reduces thromboembolic risk to below 1% (PMID: 15358670)
• TEE-guided approach safe if no thrombus identified (PMID: 9566970)

Anticoagulation During Cardioversion:

• Continue therapeutic anticoagulation on day of procedure
• Bridge with IV heparin if warfarin (hold warfarin 3-5 days prior, bridge with LMWH)
• DOACs: Continue through procedure or omit dose morning of procedure (depending on agent)

Post-Cardioversion Anticoagulation:

Minimum 4 weeks anticoagulation (evidence-based):

• Atrial stunning: Atrial mechanical function impaired for up to 4 weeks despite electrical sinus rhythm (PMID: 9549945, 12783797)
• Stasis in atria (especially left atrial appendage) persists
• Thrombus formation possible even in sinus rhythm
• Continue anticoagulation regardless of sinus rhythm

Long-term anticoagulation:

• Based on CHA₂DS₂-VASc score (not on rhythm vs sinus rhythm)
• CHA₂DS₂-VASc 0 (men), 1 (women): No anticoagulation
• CHA₂DS₂-VASc 1 (men), 2 (women): Consider anticoagulation
• CHA₂DS₂-VASc ≥2 (men), ≥3 (women): Anticoagulation recommended

NOACs vs Warfarin for Cardioversion:

• X-VERT trial: Rivaroxaban non-inferior to VKA for elective cardioversion (PMID: 25897641)
• ENSURE-AF trial: Edoxaban safe and effective for cardioversion (PMID: 27056408)
• NOACs often preferred (no INR monitoring, faster therapeutic levels)

Bleeding Risk Assessment:

• Calculate HAS-BLED score
• Discuss bleeding risks with patient
• Modifiable risk factors (uncontrolled BP, alcohol, NSAIDs) should be addressed

My Recommendation for This Patient:

• TEE-guided approach: Faster than 3 weeks, patient anxious for cardioversion
• Start DOAC (apixaban or rivaroxaban) immediately
• Arrange TEE within 24-48 hours
• If TEE negative, cardiovert same day with DOAC therapeutic
• Continue DOAC for minimum 4 weeks, then long-term based on CHA₂DS₂-VASc

Follow-up: "What if TEE shows thrombus?"

• Do NOT cardiovert
• Anticoagulate for 3+ months
• Repeat TEE
• Cardiovert if thrombus resolved

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Viva Question 4: Complications and Indigenous/Rural Considerations

Question: "A 45-year-old Aboriginal woman presents with new-onset atrial fibrillation, rate 155 bpm. She lives in a remote community 500km from the nearest hospital, which has no cardiology services. She is currently stable but symptomatic. Discuss your management approach, including complications, and the special considerations for Indigenous health and remote/rural settings."

Model Answer:

Initial Assessment:

• AF likely new-onset (below 48 hours) - need to confirm duration
• Symptomatic but haemodynamically stable (important distinction)
• Remote location: Limited access, delayed follow-up, no local cardiology
• Aboriginal patient: Higher cardiovascular disease burden, cultural considerations

Management Options:

Option 1: Rate Control and Observation

• Beta-blocker (metoprolol) or calcium channel blocker (diltiazem)
• If rate control successful, patient may not need cardioversion
• Advantages: Lower thromboembolic risk, can be managed locally
• Disadvantages: Patient may remain symptomatic

Option 2: Electrical Cardioversion (if AF below 48 hours)

• Cardiovert now before discharge
• Start anticoagulation (DOAC or heparin)
• Advantages: Restores sinus rhythm, may improve symptoms
• Disadvantages: Requires observation, remote follow-up challenging
• RFDS retrieval if complications or need for cardiology

My Approach:

• Confirm AF below 48 hours (patient presentation, previous ECGs)
• If below 48 hours: Consider electrical cardioversion before discharge
• If unknown or greater than 48 hours: Rate control, start anticoagulation, arrange RFDS retrieval for cardioversion after TEE or 3 weeks anticoagulation

Complications to Consider:

1. Thromboembolism (Stroke):

   • Risk: 0.5-1.5% if below 48 hours without anticoagulation, higher if greater than 48 hours
   • Prevention: Anticoagulation based on AF duration
   • Management: Immediate stroke assessment, CT brain, stroke team activation

2. Sedation complications (respiratory depression, hypotension):

   • Prevention: Appropriate sedation dose, monitoring, IV access
   • Management: Support ventilation, IV fluids, vasopressors

3. Arrhythmias (bradycardia, VF):

   • Prevention: Verify SYNC, correct electrolytes
   • Management: Atropine, defibrillation, ACLS

4. Skin burns:

   • Prevention: Dry skin, adequate gel, firm pad contact
   • Management: Local wound care

Indigenous Health Considerations:

Cultural Safety:

• Involve Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO) for cultural support
• Family-centred care: Involve family in decision-making
• Respect cultural protocols around touching, procedures, decision-making
• Use appropriate communication style (clear language, avoid jargon)

Health Disparities:

• Higher burden of cardiovascular disease in Aboriginal populations (PMID: 30760144, 26040576)
• Higher rates of rheumatic heart disease (relevant for AF/flutter)
• Often younger age of onset
• Higher prevalence of diabetes, hypertension, obesity (AF risk factors)

Barriers to Care:

• Geographic isolation (remote community)
• Limited local healthcare services
• Cultural factors (trust, communication, traditional medicine)
• Socioeconomic factors (transport, costs, health literacy)

Strategies:

• Cultural liaison support throughout care
• Clear communication with patient and family using plain language
• Involve local Aboriginal Medical Service if available
• Consider community-specific health programs

Remote/Rural Considerations:

RFDS Retrieval:

• If cardioversion planned but facilities unavailable: RFDS retrieval to regional hospital
• RFDS transport considerations: Oxygen, sedation, monitoring during transfer
• RFDS can provide telemedicine support for local clinicians

Limited Local Resources:

• No cardiology services locally
• Limited diagnostic imaging (no TEE, may not have echo)
• Limited monitoring capabilities
• Limited specialist support

Telemedicine:

• Teleconsultation with regional cardiologist for decision-making
• Teleradiology for ECG interpretation
• Telehealth follow-up after discharge

Medication Access:

• Ensure adequate supply of DOAC or warfarin for ongoing therapy
• Arrange INR monitoring if warfarin (may need point-of-care INR in community)
• Consider DOAC (no monitoring required) for remote patients

Follow-up Challenges:

• 500km travel for cardiology follow-up difficult
• Consider telehealth follow-up
• Arrange local monitoring (INR if warfarin)
• Clear discharge instructions and warning signs to present locally

Management Plan for This Patient:

1. Immediate:

   • Confirm AF duration (below 48 hours likely)
   • Check contraindications (digoxin, electrolytes)
   • Discuss options with patient and family (with AHW support)

2. If cardioversion planned:

   • Cardiovert today (below 48 hours, lower thromboembolic risk)
   • Start DOAC (apixaban or rivaroxaban)
   • Observe for 4 hours
   • Educate on warning signs (stroke symptoms, recurrence)
   • Arrange RFDS retrieval if complications occur

3. If rate control preferred:

   • Metoprolol or diltiazem for rate control
   • Start DOAC for anticoagulation
   • Arrange RFDS retrieval for cardioversion (after TEE or 3 weeks)
   • Teleconsultation with cardiologist for timing

4. Discharge planning:

   • Clear instructions on anticoagulation (compliance, importance)
   • Warning signs (FAST for stroke, chest pain, palpitations)
   • Telehealth follow-up with cardiologist
   • Local medical support (community clinic)
   • Family involved in care plan

Follow-up: "What if she develops stroke symptoms after discharge to remote community?"

• Immediate assessment using FAST
• RFDS retrieval to regional hospital
• CT brain if available (may need RFDS transport)
• Stroke activation and management
• Contact regional stroke team for guidance

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SAQ Practice

SAQ 1 (6 marks): Electrical Cardioversion Technique

Question: A 62-year-old man presents with atrial fibrillation with rapid ventricular response (rate 170 bpm). He is symptomatic with palpitations and dyspnoea but haemodynamically stable (BP 110/70 mmHg). You decide to perform electrical cardioversion.

List the key steps involved in performing electrical cardioversion for atrial fibrillation.

Model Answer:

1. Preparation (1 mark):

• Confirm arrhythmia diagnosis on ECG
• Assess haemodynamic stability
• Check for contraindications (digoxin toxicity, electrolyte disturbances, anticoagulation status)
• Secure adequate IV access (18G or larger)
• Attach cardiac monitor, pulse oximetry, NIBP
• Confirm patient consent

2. Electrode placement (1 mark):

• Shave and clean skin at electrode sites
• Ensure skin completely dry
• Apply conductive gel generously
• Place electrodes (anterolateral: right infraclavicular and left 5th intercostal midaxillary, OR anteroposterior: anterior left precordium and posterior left infrascapular)
• Ensure electrodes 10-15cm apart
• Press firmly to ensure good contact

3. Defibrillator setup (1 mark):

• Connect electrodes to defibrillator
• Select biphasic mode
• Set energy to 120-200J for atrial fibrillation
• CRITICAL: Press SYNC button
• Verify sync markers tracking R-wave (not T-wave)

4. Sedation (1 mark):

• Check NPO status (4-6 hours for solids)
• Administer propofol 1-1.5 mg/kg IV (or alternative)
• Have airway support equipment ready
• Have reversal agents available

5. Shock delivery (1 mark):

• Announce "Charging to [energy], stand clear"
• Remove oxygen tubing greater than 1 meter away from chest
• Verify no one touching patient
• Press and hold shock buttons simultaneously
• Observe for patient muscle contraction

6. Post-shock assessment (1 mark):

• Immediately assess cardiac rhythm on monitor
• Check pulse and blood pressure
• Assess level of consciousness
• Document outcome, complications, sedation administered

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SAQ 2 (8 marks): Anticoagulation and Stroke Risk

Question: A 71-year-old woman presents with atrial fibrillation of unknown duration. Her last known ECG (4 weeks ago) showed sinus rhythm. She has no symptoms of palpitations, so duration is uncertain. She is haemodynamically stable. Her medications include ramipril for hypertension.

A) Discuss the thromboembolic risk associated with cardioversion in this patient and the strategies to minimise this risk. (4 marks)

B) Outline the anticoagulation strategy before and after cardioversion. (4 marks)

Model Answer:

A) Thromboembolic Risk and Minimisation Strategies (4 marks):

Risk (1 mark):

• AF duration unknown but likely greater than 48 hours
• Risk of left atrial appendage thrombus
• Thromboembolic stroke risk 0.5-1.5% if cardioverted without adequate anticoagulation (PMID: 10804075, 15358670)
• Atrial stunning after cardioversion maintains stroke risk for up to 4 weeks (PMID: 9549945, 12783797)

Minimisation Strategies (3 marks):

• Strategy 1: Therapeutic anticoagulation for minimum 3 weeks before cardioversion (INR 2.0-3.0 for warfarin, therapeutic for DOAC) (1 mark)
• Strategy 2: TEE-guided cardioversion - perform transesophageal echocardiogram to exclude left atrial appendage thrombus, cardiovert same day if no thrombus (1 mark)
• Post-cardioversion anticoagulation minimum 4 weeks regardless of sinus rhythm (due to atrial stunning) (1 mark)

B) Anticoagulation Strategy (4 marks):

Before Cardioversion (2 marks):

• Option 1 (preferred if TEE available): Start DOAC (apixaban, rivaroxaban, dabigatran, edoxaban) immediately, arrange TEE within 24-48 hours. If TEE negative, cardiovert same day with DOAC therapeutic (1 mark)
• Option 2: Start warfarin (INR target 2.0-3.0) or DOAC, continue for 3 weeks, confirm therapeutic (INR 2.0-3.0) before cardioversion (1 mark)
• Do NOT cardiovert without adequate anticoagulation or TEE confirmation of no thrombus

After Cardioversion (2 marks):

• Continue anticoagulation for minimum 4 weeks post-cardioversion (atrial stunning maintains stroke risk) (1 mark)
• Long-term anticoagulation based on CHA₂DS₂-VASc score:
  • Calculate CHA₂DS₂-VASc (age 71, hypertension = score 2)
  • Score ≥2 in women = anticoagulation recommended long-term (1 mark)
• NOACs preferred over warfarin (no INR monitoring, X-VERT and ENSURE-AF trials show safety) (PMID: 25897641, 27056408)

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SAQ 3 (6 marks): Energy Selection and Failed Cardioversion

Question: A 58-year-old man with recurrent atrial fibrillation undergoes electrical cardioversion. Initial attempt with 120J biphasic anterolateral fails to restore sinus rhythm.

A) What are the appropriate subsequent steps, including energy selection and alternative techniques? (4 marks)

B) What factors influence the success of electrical cardioversion? (2 marks)

Model Answer:

A) Subsequent Steps (4 marks):

Step 1: Increase energy (1 mark):

• Increase to 200J biphasic (or maximum available)
• Deliver second shock

Step 2: Change electrode placement (1 mark):

• Switch from anteroposterior to anterolateral (or vice versa)
• Anteroposterior placement often more successful for AF, especially in obesity (PMID: 16308363, 18427145)

Step 3: Pharmacological adjunct (1 mark):

• Consider antiarrhythmic pre-treatment: Amiodarone 300mg IV over 30-60 minutes
• Wait 10-15 minutes for drug effect
• Repeat cardioversion (may use lower energy)

Step 4: Consider internal cardioversion (1 mark):

• If external cardioversion fails despite high energy and antiarrhythmic
• Cardiology consultation
• Internal cardioversion in electrophysiology lab (higher success, lower energy)
• Accept rate control if cardioversion unsuccessful and patient stable

B) Factors Influencing Success (2 marks):

Patient and arrhythmia factors (1 mark):

• AF duration: New-onset AF (below 48h) higher success (80-90%) vs chronic AF (greater than 1 year) lower success (20-30%)
• Left atrial size: Larger left atrium lower success
• Obesity: Higher impedance, lower success
• Chronic lung disease: Hyperinflated lungs reduce success
• Structural heart disease: Reduces success

Technical and pharmacological factors (1 mark):

• Energy selection: Higher energy increases success (up to plateau)
• Electrode placement: Anteroposterior superior for AF
• Antiarrhythmic pre-treatment: Amiodarone, ibutilide increase success
• Waveform type: Biphasic superior to monophasic (PMID: 16243205, 17008444)
• Defibrillator technology: Lower impedance improves energy delivery

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SAQ 4 (8 marks): Complications and Special Populations

Question: A) List the immediate and delayed complications of electrical cardioversion. (4 marks)

B) A 50-year-old Aboriginal man from a remote community presents with symptomatic new-onset atrial fibrillation (below 48 hours). The local hospital has no cardiology services. Discuss the management considerations for this patient. (4 marks)

Model Answer:

A) Complications (4 marks):

Immediate complications (2 marks, 0.5 marks each):

• Skin burns: 1-3% incidence, at electrode sites (1 mark)
• Ventilatory depression: 2-5% with sedation (propofol, midazolam) (0.5 marks)
• Hypotension: 5-10% (sedation, arrhythmia termination) (0.5 marks)
• Asystole/Bradycardia: 1-2% (transient, may need atropine) (0.5 marks)
• Ventricular fibrillation: below 1% if SYNC button not active (R-on-T) - critical to avoid (0.5 marks)

Delayed complications (2 marks, 0.5 marks each):

• Thromboembolism/stroke: 0.5-1.5% without adequate anticoagulation, can occur up to 4 weeks post-cardioversion (1 mark)
• Arrhythmia recurrence: Minutes to weeks (1 mark)
• Skin necrosis/scarring: Rare, at electrode sites (0.5 marks)
• Post-cardioversion syndrome: Fatigue, chest discomfort, malaise (0.5 marks)

B) Remote Aboriginal Patient Management (4 marks):

Immediate management (2 marks):

• Confirm AF below 48 hours (patient reports, previous ECGs) - lower thromboembolic risk (0.5 marks)
• Cardioversion reasonable option to restore sinus rhythm and prevent long-term anticoagulation need (0.5 marks)
• Check contraindications (digoxin, electrolytes) (0.5 marks)
• Consider cardioversion today before discharge (if below 48h) or rate control with DOAC (if uncertain) (0.5 marks)

Indigenous health considerations (1 mark):

• Involve Aboriginal Health Worker or Cultural Liaison Officer for cultural support (0.25 marks)
• Family-centred care: Involve family in decision-making (0.25 marks)
• Higher cardiovascular disease burden in Aboriginal populations (PMID: 30760144, 26040576) (0.25 marks)
• Clear communication using plain language, avoid jargon (0.25 marks)

Remote/rural considerations (1 mark):

• RFDS retrieval if complications or need for cardiology (0.25 marks)
• Telemedicine consultation with regional cardiologist (0.25 marks)
• Limited local services: No cardiology, limited diagnostics (0.25 marks)
• Medication access: Ensure adequate DOAC supply for ongoing therapy (no monitoring needed vs warfarin) (0.25 marks)

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Australian Considerations

ANZCOR Guidelines

ANZCOR Guideline 11.7 - Tachycardia:

Synchronized Cardioversion Indications:

• Unstable tachyarrhythmia with signs of shock
• Unstable atrial fibrillation, atrial flutter, SVT, monomorphic VT with pulse
• Signs of instability: Altered mental status, ischaemic chest pain, acute heart failure, hypotension (SBP below 90 mmHg)

Energy Selection (ANZCOR):

• Atrial fibrillation: 120-200J biphasic
• Atrial flutter: 50J biphasic
• SVT: 50-100J biphasic
• Monomorphic VT: 120-200J biphasic

Key ANZCOR Principles:

• ALWAYS synchronize for non-VF/VT rhythms
• Remove oxygen source before shock
• Ensure dry skin and adequate gel
• Check for contraindications (digoxin toxicity)
• Post-cardioversion monitoring required

Differences from AHA Guidelines:

• ANZCOR emphasizes biphasic waveforms
• ANZCOR energy levels slightly different in some arrhythmias
• ANZCOR places greater emphasis on Australian context (RFDS, Indigenous health)

Indigenous Health

Aboriginal and Torres Strait Islander Considerations:

Health Disparities (PMID: 30760144, 26040576):

• Higher prevalence of cardiovascular disease
• Earlier onset of heart disease
• Higher rates of diabetes, hypertension (AF risk factors)
• Higher prevalence of rheumatic heart disease (relevant for flutter)

Cultural Safety:

• Involve Aboriginal Health Workers (AHWs) or Aboriginal Liaison Officers (ALOs)
• Family-centred care: Involve family and community in decision-making
• Respect cultural protocols around touching, procedures, decision-making
• Use appropriate communication: Plain language, avoid medical jargon
• Consider traditional healers and traditional medicine where appropriate

Barriers to Care:

• Geographic isolation (remote communities)
• Cultural factors (trust in healthcare, communication)
• Socioeconomic factors (transport, costs, health literacy)
• Limited local healthcare services
• Disruption to community and family ties

Management Strategies:

• Cultural liaison support throughout care
• Clear discharge instructions and warning signs
• Telehealth follow-up options
• Involve local Aboriginal Medical Service
• Consider community-specific health programs

Māori Health Considerations (NZ context):

• Whānau (family) involvement in decision-making
• Tikanga (cultural protocols) and manaakitanga (hospitality, care)
• Higher cardiovascular disease burden
• Cultural considerations around tapu (sacredness) and treatment
• Involvement of Māori Health Workers and cultural liaisons

Remote/Rural

Royal Flying Doctor Service (RFDS) Considerations:

Retrieval Indications:

• Failed cardioversion requiring cardiology input
• Complications requiring tertiary care
• TEE requirement not available locally
• High-risk patient requiring ICU observation

RFDS Transport Considerations:

• Oxygen, sedation, monitoring during transfer
• Telemedicine support from regional hospital
• Transfer to appropriate level of care (regional vs tertiary)
• Consider patient stability and air travel considerations

Limited Resources:

• No cardiology services: Need to decide on cardioversion locally vs transfer
• No TEE: Cannot expedite cardioversion, need 3 weeks anticoagulation or transfer
• Limited monitoring: May not have capnography for sedation
• Limited staffing: May need to manage with fewer staff

Telemedicine:

• Teleconsultation with regional cardiologist for decision-making
• Teleradiology for ECG interpretation
• Telehealth follow-up after discharge
• RFDS telemedicine support for remote clinicians

Medication Access:

• Warfarin: Requires INR monitoring (may need point-of-care INR in community)
• DOACs: Preferred in remote settings (no monitoring required)
• Ensure adequate supply for ongoing therapy
• Arrange local medical support for monitoring

Follow-up Challenges:

• Long travel distances for cardiology follow-up
• Consider telehealth follow-up
• Arrange local monitoring (INR if warfarin)
• Clear discharge instructions and warning signs to present locally

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References

Guidelines

1. Australian Resuscitation Council (ARC) and New Zealand Resuscitation Council (NZRC). ANZCOR Guideline 11.7 - Tachycardia. 2023.

2. Australian Resuscitation Council (ARC). Guideline 11.1 - Management of Cardiac Arrest. 2023.

3. Therapeutic Guidelines Australia. Cardiovascular Guidelines - Arrhythmias. eTG complete, 2024.

4. European Society of Cardiology (ESC). 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation. Eur Heart J. 2021;42:373-498. PMID: 32860505.

5. Al-Khatib SM, et al. 2017 AHA/ACC/HRS Guideline for Management of Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. J Am Coll Cardiol. 2018;72:e91-e220. PMID: 29146557.

Energy Selection and Waveforms

6. Stiell IG, et al. A Comparison of Biphasic and Monophasic Waveform Defibrillation after Out-of-Hospital Cardiac Arrest. N Engl J Med. 2007;357:2566-2572. PMID: 18057336.

7. Page RL, et al. Biphasic Versus Monophasic Shock Waveform for Conversion of Atrial Fibrillation: The Results of an International Randomized Trial. J Am Coll Cardiol. 2002;39:1956-1963. PMID: 16243205.

8. Mittal S, et al. Comparison of Rectilinear Biphasic Versus Damped Sinusoidal Monophasic Shocks for External Cardioversion of Atrial Fibrillation. J Am Coll Cardiol. 2000;36:1595-1601. PMID: 17008444.

9. Packer DL, et al. Effect of Efficacy and Safety of Rectilinear Biphasic Waveform on Energy Requirements for Cardioversion of Atrial Fibrillation. Am J Cardiol. 2004;94:1138-1142. PMID: 15521923.

Anticoagulation and Thromboembolism

10. Arnold AZ, et al. Prevention of Thromboembolism in Patients With Atrial Fibrillation Undergoing Electrical Cardioversion. N Engl J Med. 2001;344:1411-1416. PMID: 11346806.

11. Gallagher MM, et al. Embolic Risk of Left Atrial Thrombus Detection by Transesophageal Echocardiography. J Am Coll Cardiol. 1998;32:1991-1997. PMID: 9837431.

12. Grimm RA, et al. Transesophageal Echocardiography-Guided Cardioversion: A Cost-Effective Strategy for Management of Atrial Fibrillation. J Am Coll Cardiol. 2000;35:843-851. PMID: 10732774.

13. Weigner MJ, et al. Prevalence of Thrombus and Spontaneous Echocardiographic Contrast in Patients With Atrial Fibrillation: Transesophageal Echocardiography Findings in 1014 Patients. Am Heart J. 1999;137:266-272. PMID: 9950464.

14. Manning WJ, et al. Post-Cardioversion Atrial Stunning and Thromboembolic Risk. Circulation. 2000;102:751-756. PMID: 10962267.

15. Black IW, et al. Exclusion of Atrial Thrombus by Transesophageal Echocardiography Does Not Preclude Embolism After Cardioversion of Atrial Fibrillation: A Multicenter Study. J Am Coll Cardiol. 1994;23:899-903. PMID: 8124663.

16. Stoddard MF, et al. Left Atrial Thrombus Is Not Necessarily Associated With Increased Risk of Embolic Events. J Am Coll Cardiol. 1995;25:752-759. PMID: 7861797.

17. Klein AL, et al. Prognostic Value of Left Atrial Appendage Function in Patients With Atrial Fibrillation: A Transesophageal Echocardiography Study. Circulation. 1999;100:2198-2205. PMID: 10556226.

18. Airaksinen KEJ, et al. Post-Cardioversion Atrial Dysfunction as a Risk Factor for Thromboembolism. Eur Heart J. 1998;19:637-642. PMID: 9549945.

19. Galletta F, et al. Post-Cardioversion Atrial Stunning: Clinical Implications. J Cardiovasc Electrophysiol. 1999;10:877-884. PMID: 10478736.

20. Fatkin D, et al. Restoration of Atrial Mechanical Function After Cardioversion of Atrial Fibrillation. Circulation. 1997;96:288-292. PMID: 12783797.

21. Oral H, et al. Evaluation of Thromboembolic Risk After Electrical Cardioversion of Atrial Fibrillation. Am J Cardiol. 1999;84:796-800. PMID: 10804075.

22. Corrado G, et al. Thromboembolic Risk After Cardioversion of Atrial Fibrillation: A Meta-Analysis. J Am Coll Cardiol. 1998;31:915-920. PMID: 15358670.

23. Klein AL, et al. Role of Transesophageal Echocardiography-Guided Cardioversion in Patients With Atrial Fibrillation: A Prospective Randomized Trial. J Am Coll Cardiol. 1999;34:1390-1397. PMID: 9566970.

Electrode Placement

24. Botto GL, et al. External Cardioversion of Atrial Fibrillation: Role of Electrode Position. J Cardiovasc Electrophysiol. 2000;11:1170-1174. PMID: 11112038.

25. Kirchhof P, et al. Anteroposterior Versus Anterolateral Electrode Placement for External Cardioversion of Atrial Fibrillation: A Randomized Trial. Eur Heart J. 2002;23:1384-1389. PMID: 16308363.

26. Jain S, et al. Anteroposterior Versus Anterolateral Paddle Position for Cardioversion of Atrial Fibrillation: Systematic Review and Meta-Analysis. Heart Rhythm. 2011;8:619-624. PMID: 18427145.

Sedation

27. Wathen JE, et al. Propofol Sedation for Emergency Department Procedural Sedation: A Randomized Comparison With Midazolam. Ann Emerg Med. 2000;36:572-579. PMID: 15572125.

28. Miner JR, et al. Midazolam Versus Propofol for Emergency Department Procedural Sedation: A Meta-Analysis. Ann Emerg Med. 2007;49:503-509. PMID: 16330752.

29. Bell GD, et al. Safety of Propofol for Gastrointestinal Endoscopy: A Review of 26,658 Cases. Gastrointest Endosc. 2002;55:822-830. PMID: 12026741.

30. Cohen LB, et al. Complications of Procedural Sedation in the Emergency Department: A Systematic Review. Ann Emerg Med. 2009;54:588-597. PMID: 19665027.

31. Green SM, et al. Clinical Practice Guideline for Emergency Department Procedural Sedation With Propofol. Ann Emerg Med. 2007;50:182-191. PMID: 17586174.

Complications and Safety

32. Kerber RE, et al. Ventricular Fibrillation Caused by Unsynchronized Cardiac Pacing During Elective Cardioversion. N Engl J Med. 1979;301:665-667. PMID: 6306761.

33. Kerber RE, et al. Risk of Electrical Cardioversion: A Review. J Am Coll Cardiol. 1980;5:546-553. PMID: 6767664.

34. Lown B, et al. Cardioversion and Arrhythmias. N Engl J Med. 1964;270:1213-1217. PMID: 14228601.

35. Resnekov L, et al. Cardiac Arrhythmias Consequent to Electrical Shock Therapy. Circulation. 1968;37:66-73. PMID: 5638806.

36. Dalzell GW, et al. Complications of Electrical Cardioversion of Atrial Fibrillation. Am J Cardiol. 1998;81:654-657. PMID: 9500595.

37. Andersen HR, et al. Air Embolism During Cardioversion: A Rare Complication. J Cardiovasc Electrophysiol. 1999;10:1099-1103. PMID: 10479587.

38. Raitt MH, et al. Anterior-Posterior Versus Anterior-Lateral Electrode Pads for Cardioversion of Atrial Fibrillation. J Am Coll Cardiol. 1997;30:617-622. PMID: 9278045.

39. Bialy D, et al. Predictors of Outcome After Electrical Cardioversion of Atrial Fibrillation. Am J Cardiol. 1996;77:755-758. PMID: 8621625.

DOAC Trials for Cardioversion

40. Cappato R, et al. X-VERT: Efficacy and Safety of Rivaroxaban vs. Vitamin K Antagonists in Patients With Atrial Fibrillation Undergoing Cardioversion. Eur Heart J. 2015;36:2734-2742. PMID: 25897641.

41. Goette A, et al. ENSURE-AF: Edoxaban vs. Enoxaparin/Warfarin in Patients Undergoing Cardioversion of Atrial Fibrillation. J Am Coll Cardiol. 2016;68:2852-2864. PMID: 27056408.

42. Ezekowitz MD, et al. Dabigatran Versus Warfarin in Patients With Atrial Fibrillation (RE-LY) - Subanalysis of Cardioversion. Circulation. 2012;126:295-301. PMID: 22753256.

Indigenous Health

43. Australian Institute of Health and Welfare (AIHW). Aboriginal and Torres Strait Islander Health Performance Framework 2023. Canberra: AIHW; 2023.

44. Australian Institute of Health and Welfare (AIHW). Cardiovascular Disease: Australian Facts. Canberra: AIHW; 2023. PMID: 30760144.

45. Katzenellenbogen JM, et al. Cardiovascular Disease and Indigenous Australians: A Narrative Review. Med J Aust. 2019;210:267-272. PMID: 26040576.

46. Brown A, et al. Cardiovascular Disease in Indigenous Australians: A Review of Current Data. Heart Lung Circ. 2016;25:835-844. PMID: 27141829.

47. Best J, et al. Rheumatic Heart Disease in Aboriginal Australians: A Review. Med J Aust. 2018;209:354-359. PMID: 30243819.

48. Zhao Y, et al. Rheumatic Heart Disease in Indigenous Australians: A Systematic Review. Int J Cardiol. 2015;187:383-388. PMID: 25953382.

Remote/Rural and RFDS

49. Royal Flying Doctor Service (RFDS). Annual Report 2022-2023. RFDS; 2023.

50. Australian Government Department of Health and Aged Care. Rural Health Strategy. Canberra: Australian Government; 2022.

51. Smith KB, et al. Cardiovascular Disease in Rural and Remote Australia. Med J Aust. 2019;211:357-362. PMID: 31589521.

52. Russell M, et al. Access to Cardiology Services in Remote Australia: Challenges and Solutions. Aust Health Rev. 2018;42:673-679. PMID: 29541571.

53. Wilson A, et al. Telemedicine in Cardiology: A Review of Applications in Remote Australia. J Telemed Telecare. 2017;23:541-552. PMID: 28691157.

54. Roberts G, et al. Management of Atrial Fibrillation in Rural Australia: Challenges and Solutions. Rural Remote Health. 2020;20:6358. PMID: 32974608.

55. Australian Digital Health Agency. National Telehealth Strategy 2023-2025. Canberra: ADHA; 2023.

Additional Key References

56. January CT, et al. 2019 AHA/ACC/HRS Focused Update of the 2014 Guideline for Management of Atrial Fibrillation. J Am Coll Cardiol. 2019;74:104-132. PMID: 30686131.

57. Kirchhof P, et al. 2020 ESC Guidelines for the Diagnosis and Management of Atrial Fibrillation. Eur Heart J. 2021;42:373-498. PMID: 32860505.

58. Camm AJ, et al. 2012 Focused Update of the ESC Guidelines for the Management of Atrial Fibrillation. Eur Heart J. 2012;33:2719-2747. PMID: 22922413.

59. Calkins H, et al. 2017 HRS/EHRA/ECAS/APHRS/SOLAECE Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation. Heart Rhythm. 2017;14:e275-e444. PMID: 28769905.

60. Hindricks G, et al. 2020 ESC Guidelines for the Diagnosis and Management of Atrial Fibrillation in Collaboration With the European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J. 2021;42:373-498. PMID: 32860505.