⚡ Torsades de Pointes (Polymorphic VT): Occurs in repetitive, non-sustained paroxysms but can degenerate into VF. 💉 First-line: IV magnesium 8 mmol (2 g) bolus over 10–15 mins in 50–100 ml 5% dextrose or saline. ❌ Avoid amiodarone. Correct K/Mg/Ca. Consider pacing, isoprenaline (except congenital LQTS), and defibrillation if unstable.

📖 About

Coined by Dessertenne in 1966.
A polymorphic ventricular tachycardia with the QRS axis “twisting around the baseline.”
Commonly associated with prolonged QTc >460 ms.
Drug-associated risk varies - see www.qtdrugs.org.

📌 Definition

Polymorphic VT with continuously changing QRS axis.
Seen in congenital or acquired Long QT syndrome.
Often due to inhibition of the HERG potassium channel.

🖥️ Electrocardiogram

🧬 Genetics

LQT1 & LQT2 → slow potassium channels.
LQT3 → sodium channel defects.
LQT4–12 → rarer subtypes.
Congenital long QT: autosomal dominant, more pronounced in females.

📊 Epidemiology

Females 2–3x more likely to develop TdP.
Drug-induced QT prolongation more common in women.

🩺 Clinical

Occurs in bursts, often self-terminating.
Symptoms: presyncope, syncope, hypotension, pulmonary oedema.
May deteriorate to sustained VT/VF → cardiac arrest.

⚠️ Risk Factors

Congenital: Romano-Ward (AD), Jervell-Lange-Nielsen (AR + deafness).
Acquired: electrolyte disorders (↓K, ↓Ca, ↓Mg), medications, bradycardia.
Other: baseline ECG abnormalities, renal or liver impairment, female sex.

💊 Causes of Acquired Long QT

Electrolyte/metabolic: hypokalaemia, hypocalcaemia, hypomagnesaemia, hypothyroidism, hypothermia.
Drugs: amiodarone, disopyramide, flecainide, erythromycin, terfenadine, TCAs, quinidine, lithium, phenothiazines. 👉 Always check in BNF.

🔎 Investigations

FBC, U&E, Mg, Ca, TFTs, troponin if ACS suspected.
ECG: twisting QRS, prolonged QTc often >500 ms.
Echocardiogram: rule out structural heart disease.

🛠️ Management

Stop offending drugs (esp. amiodarone, class I/III antiarrhythmics).
IV magnesium sulphate: 8 mmol (2 g) bolus → then 72 mmol (18 g) over 24 hrs.
Pacing (atrial > ventricular) if bradycardia-dependent TdP.
IV isoprenaline: useful for acquired TdP but contraindicated in congenital LQTS.
Defibrillation if unstable.
Congenital LQTS: beta-blockers mainstay; consider ICD or left stellate ganglion block for refractory cases.
Acquired LQTS: beta-blockers contraindicated (bradycardia worsens risk).

📚 References

AHA/ACC: Prevention of Torsades in Hospital Settings

💡 Teaching Pearl: TdP is always a “red flag rhythm.” Think: correct electrolytes, stop QT-prolonging drugs, give magnesium, pace or shock if needed.

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Torsades de pointes TdP (Polymorphic VT)