This handout is for cardiogenic shock — long-qt torsades de pointes (tdp) electrical storm. Your care team identified this based on: ecg qtc > 500 ms (bazett or fridericia) with tdp runs on telemetry / 12-lead — tdp electrical storm.
Other reasons your team may use this plan: recurrent syncope or aborted scd in patient with qtc > 480 ms — concern for congenital or acquired lqt with tdp; recent exposure to qt-prolonging drug (class iii antiarrhythmic, macrolide, fluoroquinolone, antipsychotic, methadone, ondansetron, tca, citalopram) precipitating tdp — acquired lqt; family history of sudden death <40 y + qtc > 470 ms (m) or > 480 ms (f) — congenital lqt high concern.
Take these medications exactly as prescribed. Do not stop or change a dose without talking to your provider.
| Medication | Starting dose | How | When | What it does |
|---|---|---|---|---|
| magnesium sulfate | 2 g IV bolus over 5–15 min then 2 g/h infusion REGARDLESS of measured Mg level | IV | continuous; titrate to TdP suppression | AHA 2020 ACLS — FIRST-LINE for TdP regardless of measured Mg level; mechanism stabilizes myocardial membrane independent of measured Mg; HRS 2017 PMID 28219760 |
| isoproterenol | 0.5–2 µg/min IV titrate to HR 90–110 | IV | continuous; titrate to HR target + TdP suppression | AHA 2020 ACLS — increases HR which shortens QT and prevents R-on-T; useful for bradycardia-dependent TdP (LQT3 + acquired); CONTRAINDICATED in LQT1/2 acute (adrenergic trigger) |
| potassium chloride | 20–40 mEq IV/PO until K ≥4.5 | IV/PO | PRN | Hypokalemia is major TdP precipitant; aggressive K repletion to ≥4.5 mandatory; HRS 2017 |
| norepinephrine | 0.05–0.5 µg/kg/min IV titrate | IV | continuous; titrate to MAP ≥65 | SOAP-II PMID 20200382 — first-line in CS; α-1 effect supports MAP; CAUTION in LQT1/2 (adrenergic trigger — minimize dose) |
| propranolol | CONGENITAL LQT long-term: propranolol 2–4 mg/kg/d divided BID-QID; do NOT initiate acutely if bradycardia-dependent acquired TdP | PO | BID-QID; lifelong in congenital LQT1/2 | Schwartz International LQTS Registry — propranolol mortality reduction in congenital LQT1/2; FIRST-LINE long-term per HRS 2017 Class I |
| nadolol | CONGENITAL LQT long-term: nadolol 1–1.5 mg/kg/d daily | PO | daily; lifelong in congenital LQT1/2 (preferred over propranolol per recent registry data) | Long half-life + non-selective; recent registry data suggest superior to propranolol in LQT1/2; HRS 2017 Class I |
Plan: LQT-TdP storm with CS — MgSO4 + electrolyte repletion + drug withdrawal + pacing/isoproterenol if bradycardia-dependent; AVOID Class IA + III antiarrhythmics; congenital LQT long-term β-blocker
Contact your care team if any of the following happen:
Call 911 or go to the nearest emergency room right away if you have:
CONGENITAL LQT — EP / inherited-arrhythmia clinic 1–4 wks; long-term β-blocker (propranolol or nadolol — Schwartz registry mortality reduction); ICD if high-risk; LCSD for refractory; lifestyle (LQT1 avoid swimming; LQT2 avoid loud noises; LQT3 caution sleep alone); cascade testing first-degree relatives. ACQUIRED LQT — drug-avoidance education + medic-alert bracelet; review home med list against www.crediblemeds.org; root-cause analysis; cardiology follow-up at 1–4 wks; baseline ECG to confirm QTc normalization (most acquired QT prolongation reverses within 24–72 h of drug withdrawal)
Guideline: HRS 2017 Inherited Arrhythmia Syndromes Expert Consensus (Al-Khatib PMID 28219760); AHA 2020 ACLS; Schwartz International LQTS Registry; ESC 2022 VA / SCD prevention; SCAI 2022 CS staging (Naidu PMID 35718438); CredibleMeds (www.crediblemeds.org) curated QT-prolonging drug list