Post-Surgical Tachycardia

Causes

Common (PACU setting)

Serious / Life-Threatening (must be ruled out)

Why Tachycardia Causes Myocardial Ischemia

Evaluation Approach

• HR >150 bpm + hypotension + signs of hypoperfusion (altered mental status, chest pain, shock) = UNSTABLE - act immediately

• Administer supplemental oxygen
• Obtain 12-lead ECG and determine the underlying rhythm
• Assess and treat reversible causes (pain, fluid status, oxygenation, electrolytes)
• Check for: hypoxemia, hypercapnia, electrolyte abnormalities (K+, Mg++), acidemia, anemia, drug effects, substance withdrawal

• SVT with rapid ventricular response, atrial fibrillation, or atrial flutter = immediate synchronized cardioversion (per AHA 2020 ACLS guidelines)
• Identify and treat underlying cause simultaneously

Management by Cause

Postoperative Atrial Fibrillation

Key Points

• Always exclude hemorrhage, PE, and sepsis before attributing tachycardia to benign causes
• Silent myocardial injury (elevated troponin without symptoms) is far more common post-op than clinically recognized; check troponin if ECG changes are present or the patient is high-risk
• Adequate analgesia is both treatment and prevention - pain-driven sympathetic tachycardia is avoidable

Management of Tachycardia

Step 1: Initial Assessment (ALL patients)

• Attach monitoring (ECG, pulse oximetry, BP)
• Provide supplemental oxygen - hypoxemia is a common cause of tachycardia and must be corrected first
• Obtain 12-lead ECG to characterize the rhythm
• Do NOT delay cardioversion if the patient is obviously unstable

Step 2: Is the Patient Stable or Unstable?

• Acute altered mental status
• Ischemic chest discomfort
• Acute heart failure
• Hypotension or other signs of shock
• HR typically >150 bpm

UNSTABLE Patient → Immediate Synchronized Cardioversion

STABLE Patient → Narrow-Complex vs. Wide-Complex

A. Narrow-Complex Tachycardia (QRS <0.12 sec) - Regular

• Valsalva maneuver (preferred; modified supine with leg elevation is most effective)
• Carotid sinus massage
• Effective in ~40-50% of patients

• First dose: 6 mg rapid IV push + NS flush
• Second dose: 12 mg if required
• Warn the patient of transient chest tightness and sense of "impending doom"
• Diagnostic and therapeutic: may transiently reveal underlying flutter waves or diagnose VT vs. SVT

• IV verapamil or diltiazem (non-DHP calcium channel blockers)
• IV beta-blocker (metoprolol or esmolol)
• DC cardioversion if hemodynamically unstable or all pharmacologic measures fail

B. Narrow-Complex Tachycardia - Irregular

C. Wide-Complex Tachycardia (QRS ≥0.12 sec) - Regular

• Give adenosine IV during ECG monitoring - it may clarify the diagnosis by transiently interrupting AV conduction

Key rule: Use only ONE antiarrhythmic drug. Do NOT add a second without expert consultation. All three agents cause hypotension in up to 30% of patients.

• Idiopathic VT (no structural heart disease): Beta-blockers often terminate it
• Left ventricular fascicular reentrant tachycardia: IV verapamil or diltiazem (do NOT give calcium channel blockers for other VTs - risk of hemodynamic collapse)

D. Wide-Complex Tachycardia - Irregular

• WPW + AF: Avoid AV nodal blocking agents (adenosine, verapamil, digoxin, beta-blockers) - they can accelerate conduction down the accessory pathway and precipitate VF. Use procainamide or cardioversion
• Polymorphic VT / Torsades de pointes: Correct electrolytes (K+, Mg++); IV magnesium sulfate 2g over 15 min; stop QT-prolonging drugs; overdrive pacing if recurrent

Reversible Causes to Correct in All VT

• Hypoxemia / hypercapnia
• Hypokalemia / hypomagnesemia
• Digitalis toxicity
• Acidosis
• Acute myocardial ischemia (check ECG + troponin)
• Increased sympathetic tone from pain, fever, or acute illness

Long-Term / Definitive Management

Management of Tachycardia - Quick Reference

Step 1: Initial Steps (All Patients)

• O₂, monitoring, 12-lead ECG
• Identify and correct reversible causes (hypoxia, pain, hypovolemia, electrolytes)

Step 2: Stable or Unstable?

UNSTABLE (hypotension, AMS, chest pain, shock, HR >150)

STABLE → Classify by QRS width

Narrow Complex (QRS <0.12s) - Regular SVT

1. Vagal maneuvers (Valsalva, carotid massage) - effective ~40-50%
2. Adenosine 6 mg IV rapid push → 12 mg if needed
3. Verapamil / Diltiazem or Beta-blocker (metoprolol/esmolol) IV

Narrow Complex - Irregular (AF/MAT)

• Rate control: Metoprolol, diltiazem, digoxin (if BP tenuous), or amiodarone
• Rhythm control: Electrical or pharmacological cardioversion (anticoagulate if AF >48 hrs)
• Target HR: <80 bpm rest, <100 bpm exercise

Wide Complex (QRS ≥0.12s) - Regular → Assume VT

• Adenosine IV if uncertain VT vs SVT with aberrancy (diagnostic + may be therapeutic)
• Procainamide 20-50 mg/min IV (max 17 mg/kg) - preferred pharmacologic agent
• Amiodarone 150 mg IV over 10 min if procainamide contraindicated
• Sotalol 100 mg IV over 5 min
• Use only ONE antiarrhythmic at a time

Wide Complex - Irregular

• WPW + AF: Avoid AV nodal blockers → use Procainamide or cardioversion
• Torsades de pointes: Magnesium 2g IV + stop QT-prolonging drugs

Long-Term Definitive Treatment