Critical ECG Analysis - Mrs. Manorama, 76F

ECG Findings

What is Actually Happening Here

1. Patient is on noradrenaline (vasopressor) = severely ill, likely in cardiogenic or distributive shock
2. Urine output only 100 mL overnight = oliguric acute kidney injury / renal failure - potassium is not being excreted
3. ECG shows massively wide QRS with near-sine-wave morphology in precordial leads

The progression of hyperkalemic ECG changes is:

Emergency Management - Right Now

Step 1: Cardiac Membrane Stabilization (IMMEDIATE - within minutes)

• OR Calcium chloride 10%: 10 mL (1 g) via central line only
• This does NOT lower potassium - it buys time by stabilizing the myocardium
• Effect onset: 1-3 minutes; duration: 30-60 minutes

Step 2: Shift Potassium Intracellularly (Onset 15-30 min)

• Insulin + Dextrose: Actrapid 10 units IV + 25g dextrose (50 mL 50% dextrose) IV - lowers K by ~1 mEq/L
• Sodium bicarbonate: 50-100 mEq IV if acidotic (pH <7.3) - redistributes K intracellularly
• Salbutamol (nebulized): 10-20 mg via nebulizer - additional intracellular shift

Step 3: Remove Potassium from Body

• Furosemide: Patient is oliguric - use cautiously; may try 40-80 mg IV to encourage diuresis, but likely will not work with severe AKI
• Sodium polystyrene sulfonate (Kayexalate): 15-30 g orally or rectally - onset 1-2 hours
• Dialysis/CRRT - this patient almost certainly needs emergent hemodialysis or CRRT given oliguria + severe hemodynamic compromise. This is the definitive treatment.

What NOT to Do

• Do NOT attempt DC cardioversion for this rhythm - you are not treating AF
• Do NOT give more amiodarone - it will not help and prolongs QT further in an already compromised conduction system
• Do NOT stop noradrenaline abruptly - maintain hemodynamic support

Immediate Investigations Needed

Summary

• Comprehensive Clinical Nephrology 7th Ed - ECG changes table: sine wave pattern correlates with K+ >9 mmol/L
• Tintinalli's Emergency Medicine - hyperkalemia treatment protocol with calcium, insulin, bicarbonate
• Goldman-Cecil Medicine - hyperkalemia causing sinoventricular rhythm preceding VF

Revised Assessment - K+ is 3.89 mEq/L (Normal)

Re-reading the ECG

• HR 145 bpm
• QRS 142 ms (markedly wide)
• P axis -150° (abnormal)
• QTc 468 ms (prolonged)
• The precordial leads show a near-sinusoidal wide-complex pattern

Differential Diagnosis - Wide Complex Tachycardia at 145 bpm

The Amiodarone Factor - Important

• The wide QRS (142 ms) may be partly or wholly drug-induced conduction slowing
• The QTc of 468 ms is concerning - amiodarone + hypotension + electrolyte shifts create a risk of Torsades de Pointes
• If this IS VT and the patient is already on amiodarone, adding more amiodarone is unlikely to help and may worsen conduction

Critical Questions to Answer NOW

• Regular = favour VT or SVT with BBB
• Irregular = favour AF with aberrancy
• The machine said "AF" but the tracing appears fairly regular in the limb leads - please look at the rhythm strip carefully

• Dissociated P waves = VT (AV dissociation)
• No P waves + irregular = AF with aberrancy

• A pre-existing BBB on a prior ECG would support AF with aberrancy rather than VT

Immediate Management Plan

If hemodynamically unstable (which she is - on noradrenaline):

Treat as VT - perform synchronised DC cardioversion immediately

• Start at 200J biphasic (or 150J if that is the device setting)
• Sedate if conscious (midazolam 1-2 mg IV + fentanyl 25-50 mcg IV titrated)
• Keep crash trolley at bedside

If a brief pause before cardioversion is acceptable:

• If truly irregular wide-complex tachycardia: AF with aberrancy - amiodarone may help, but she is already on it
• If regular: monomorphic VT - cardiovert

Step 3 - After cardioversion / rhythm control:

• Check 12-lead in sinus rhythm - look for baseline BBB, delta waves (WPW), or ischemic changes
• Troponin - tachycardia at 145 in a sick elderly woman - rule out ACS driving the rhythm
• Echo - LV function? The tachycardia + hypotension may be from underlying structural heart disease
• Electrolytes panel: Mg2+ (hypomagnesaemia worsens AF and predisposes to TdP), Ca2+, Na+

Step 4 - Review the amiodarone:

• If QTc remains >500 ms after rhythm control, consider reducing or stopping the amiodarone infusion
• Switch to digoxin for AF rate control in haemodynamically compromised patients - it has less negative inotropy and does not widen QRS
• Or beta-blocker at ultra-low dose if EF is preserved

Summary of the Situation

Updated Clinical Picture - Full Problem List

• Known CAD (coronary artery disease)
• Known ischemic stroke (prior)
• Hyponatremia - now corrected
• Currently: Hypotension on noradrenaline + amiodarone infusion
• Wide-complex tachycardia at 145 bpm (machine says AF, QRS 142 ms)
• Oliguria - 100 mL overnight

How CAD + Stroke Changes Everything

1. The Wide Complex Tachycardia is Almost Certainly VT

• Wide QRS (142 ms) at 145 bpm
• Haemodynamic instability requiring vasopressors
• Oliguria (end-organ hypoperfusion)

2. The Tachycardia May Be Ischaemia-Driven

• Acute ischaemia can trigger VT even without a new infarct
• The VT itself causes demand ischaemia, creating a vicious cycle

3. Stroke History - Major Implications for Management

4. Hyponatremia - Now Corrected, But Watch For ODS

Revised Priority Management

IMMEDIATE - Right Now

• Patient is haemodynamically unstable (vasopressor-dependent) with wide-complex tachycardia
• Prior stroke is NOT a contraindication to cardioversion
• 200J biphasic, synchronised
• Sedate with IV midazolam 1-2 mg + fentanyl 25 mcg (titrate carefully - she is already hypotensive)
• Goal: restore sinus rhythm, improve cardiac output, reduce vasopressor requirement

• Rule out ACS/STEMI as the trigger for VT
• A post-conversion 12-lead will reveal baseline BBB, old infarct pattern, or ischaemic changes

• Hypomagnesaemia is common after diuresis, poor intake, and illness
• Low Mg²⁺ causes refractory AF and increases TdP risk with amiodarone
• Replace IV if <0.8 mmol/L: MgSO₄ 2g IV over 10-20 min

AFTER CARDIOVERSION

Amiodarone Infusion - Continue or Stop?

• If the rhythm is VT: amiodarone is appropriate (continue)
• If the rhythm is AF with BBB: amiodarone is appropriate (continue), but rate may be inadequate - she is already on it
• If QTc post-cardioversion is >500 ms: reduce dose and consider whether amiodarone is contributing to QRS widening
• Do NOT add any other QT-prolonging drugs

The Bigger Picture

CAD + ischaemia
    ↓
VT / AF → ↓ cardiac output
    ↓
Hypotension → ↑ noradrenaline (vasopressor)
    ↓
Renal hypoperfusion → oliguria → AKI
    ↓
± electrolyte disturbances → perpetuate arrhythmia