Tachycardia
ABCs
- ABCs, full vitals, cardiac monitor
- definition → HR > 100 bpm; instability from a tachyarrhythmia is usual at ≥ 150 bpm
- confirm → recheck rate, confirm on ECG, compare with baseline and trend
- first question: which of the two?
- physiological sinus tachycardia from an underlying cause (sepsis, pain, hypovolemia, hypoxia, anxiety) → treat the cause, not the rate
- primary tachyarrhythmia → rhythm-directed plan below
unstable, attributable to the tachyarrhythmia (any of)
- hypotension or shock
- acutely altered mental status
- ischemic chest discomfort
- acute heart failure / pulmonary edema
- instability must be attributable to the rhythm before cardioversion
HPI & examination
- symptoms: palpitations, chest pain, dyspnea, presyncope, diaphoresis, altered LOC
- triggers: pain, anxiety, hypovolemia, caffeine, new medications, withdrawal
- arrhythmia history; review treatment sheet
- infection screen
- fever, rigors, recent infection
- cough, sputum, dyspnea
- dysuria / urinary symptoms
- abdominal symptoms or diarrhea
- wounds, lines, devices, recent procedures
- current/recent antibiotics and previous cultures
- suspect PE if tachypnea or desaturation → Wells’ criteria for PE · MDCalc ↗︎
workup
- ECG
- confirm rate and rhythm
- narrow QRS < 0.12 s · wide QRS ≥ 0.12 s
- regular or irregular?
- P waves and relationship to QRS
- QTc, ischemic changes, pre-excitation
- common patterns
- narrow regular → sinus tachycardia, SVT, atrial flutter with fixed conduction
- narrow irregular → AF, flutter with variable block, MAT
- wide regular → treat as VT unless proven otherwise; SVT with aberrancy or pre-existing BBB possible
- wide irregular → pre-excited AF or polymorphic VT; avoid adenosine and AV-nodal blockers
- electrolytes: K, Mg, Ca; VBG and lactate if unwell or hypoperfused; TSH if indicated
- if infection suspected
- CBC with differential; CRP ± PCT
- cultures before antibiotics if no delay
- urinalysis, CXR, source-directed tests
management
stable, likely physiological sinus tachycardia
- treat cause: sepsis, hypovolemia, pain, anxiety, medications, electrolyte disturbance
- optimize K, Mg
- if hypovolemia suspected → balanced crystalloid 250–500 mL bolus, reassess before repeating; not routine for every tachycardic patient
unstable tachyarrhythmia → synchronized cardioversion
- call for help; pads on; IV access
- sedate when feasible; never delay the shock for sedation
- shock, sync confirmed before every shock; 2025 AHA starting energies
- atrial fibrillation → 200 J synchronized
- atrial flutter → 200 J synchronized
- regular narrow-complex tachycardia → 100 J synchronized
- monomorphic VT with a pulse → 100 J synchronized
- polymorphic VT → unsynchronized high-energy shock (defibrillation)
- unsuccessful → resynchronize, increase energy per device / local protocol
stable narrow-complex regular (likely SVT)
- vagal maneuvers first (modified Valsalva)
- adenosine
- adenosine 6 mg rapid IV push, follow immediately with rapid saline flush
- if unsuccessful → 12 mg; local protocol for any additional dose
- record/print rhythm strip during administration
- use only in regular rhythms; avoid in irregular wide-complex tachycardia and severe asthma
- reduce dose via central line or transplanted heart
stable regular monomorphic wide-complex (presumed VT)
- treat as VT unless proven otherwise; expert help early
- adenosine only if stable, regular, monomorphic and the rhythm is genuinely unclear; never in irregular or polymorphic wide-complex
- amiodarone, stable VT dosing (distinct from cardiac-arrest dosing)
- 150 mg IV over 10 min, may repeat if VT recurs
- then 1 mg/min for 6 h, then 0.5 mg/min for 18 h per local protocol
- can cause hypotension and bradycardia
- do not use in pre-excited AF
atrial fibrillation
- involve cardiology
- unstable (box above) → synchronized cardioversion
- rate control (if not unstable)
- individualize target; lenient (< 110 bpm) reasonable in many asymptomatic patients
- continuous ECG and BP monitoring
- metoprolol 2.5–5 mg IV over 2 min, up to 3 doses → avoid in decompensated HF
- verapamil (non-DHP CCB; diltiazem not stocked) 0.075–0.15 mg/kg IV over 2 min, may repeat after 30 min → stable narrow-complex rhythms only
- avoid: wide-complex tachycardia, pre-excited AF / WPW, hypotension, significant AV block, HFrEF / decompensated HF
- consider digoxin in HFrEF or when other agents contraindicated
- becomes unstable → cardiovert; do not persist with rate control
- rhythm control
- treat trigger first (e.g. sepsis); rhythm control if rhythm causes instability or remains problematic despite rate control
- pre-excited AF (e.g. WPW), wide irregular
- avoid adenosine, beta-blockers, diltiazem/verapamil, digoxin, IV amiodarone: AV-nodal blockade can precipitate VF
- expert help; cardiovert immediately if unstable
- anticoagulation
- duration < 48 h alone does not make cardioversion safe; individualize thromboembolic risk
- duration ≥ 48 h or unknown → guideline-based anticoagulation or TEE before elective cardioversion
- continue anticoagulation for appropriate duration after cardioversion
- do not delay urgent cardioversion for anticoagulation decisions
- long-term decision → CHA₂DS₂-VASc · MDCalc ↗︎
- HAS-BLED · MDCalc ↗︎: identifies modifiable bleeding risks; do not use alone to withhold anticoagulation
evidence
| source | type |
|---|---|
| 2025 AHA Adult Advanced Life Support | international guideline |
| 2026 Surviving Sepsis Campaign (sinus-tachy-from-sepsis framing) | international guideline |
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
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Last clinically reviewed · 17 August 2026 · Last updated · September 2026