Heart Rate – Tachycardia

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Tachycardia

ABCs
  • ABCs and vitals
  • cardiac monitor
  • acetaminophen 1 g IV (max 4 g/day) if febrile or in pain, then reassess
  • identify signs of shock or hypoperfusion: hypotension, altered LOC
unstable tachycardia (any of)
  • hypotension or shock
  • altered mental status
  • active ischemia (chest pain, ECG changes)
  • severe heart failure / pulmonary edema
  • pre-excitation with wide irregular QRS (e.g. WPW)
HPI & examination
  • symptoms: chest pain, dyspnea, palpitations, nausea, diaphoresis, presyncope, altered LOC
  • triggers: pain, anxiety, hypovolemia, caffeine, new medications
  • history of arrhythmias, review treatment sheet
  • suspect PE if tachypnea or oxygen desaturation present
workup
  • ECG → assess rhythm, wide vs narrow QRS
  • electrolytes: K, Mg, Ca
  • VBG and lactate
  • TSH if indicated
management
stable patients
  • treat reversible causes: sepsis, hypovolemia, pain, anxiety, medications, electrolyte disturbances
  • optimize electrolytes (K, Mg)
  • IV fluids 500-1000 mL NS or RL if no fluid overload, ESRD, or HF
unstable or symptomatic with ECG changes
  • manage by underlying cause
  • involve cardiology, pulmonology, or other specialties
  • continuous monitoring with tailored follow-up
new-onset atrial fibrillation
cardiology involvement required
urgent / emergent cardioversion indicated for
  • active ischemia
  • hypotension or shock
  • severe heart failure
  • pre-excitation (e.g. WPW with irregular wide QRS → high VF risk)
stable narrow-complex regular (likely SVT)
  • vagal maneuvers first (modified Valsalva)
  • adenosine 6 mg rapid IV push → if no response 12 mg → may repeat 12 mg
  • fast flush + arm raise after each dose; print a rhythm strip
rate control (if not unstable)
  • target HR < 110 bpm in asymptomatic with preserved EF
  • target HR < 80 bpm in HFrEF
  • first-line: beta blockers, non-DHP CCBs (diltiazem, verapamil)
  • avoid CCBs in decompensated HF
  • use IV route for rapid control
  • consider digoxin in HFrEF or when other agents contraindicated
rhythm control indicated for
  • new onset with clear trigger (e.g. sepsis)
  • instability despite rate control
  • amiodarone 150 mg IV over 10 min, then 1 mg/min for 6 h (≈60 mg/h), then 0.5 mg/min for 18 h (≈30 mg/h)
  • BP-neutral; caution in hypotension
anticoagulation
  • AF < 48 h: may consider pre-cardioversion
  • AF ≥ 48 h or unknown duration: 3 weeks anticoagulation before cardioversion (TEE may rule out thrombus for earlier cardioversion)
  • continue anticoagulation 4 weeks post-cardioversion
  • long-term: CHA₂DS₂-VASc score
related palpitations · ECG interpretation · hypotension · fever · chest pain
go deeper MOC+ Vol 2 · Cardiopulmonary covers this in the full reference. or the complete set.
studying for the IM exam? the IM Rapid Review covers tachyarrhythmias and rate control in the same format. see the sample chapter.

Last reviewed · June 2026

MOC