How should I evaluate and manage tachycardia in an adult patient?

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Evaluation and Management of Tachycardia in Adults

Immediate Assessment: Determine Hemodynamic Stability

If the patient shows acute altered mental status, ischemic chest pain, acute heart failure, hypotension, or shock, proceed directly to synchronized cardioversion without waiting for diagnostic workup. 1, 2

Initial Stabilization Steps (All Patients)

  • Attach cardiac monitor, obtain vital signs, and establish IV access 1, 2
  • Assess oxygen saturation via pulse oximetry and evaluate for increased work of breathing (tachypnea, retractions) 1, 2
  • Provide supplemental oxygen if hypoxemia or respiratory distress is present 1, 2
  • Identify and treat reversible causes (infection/sepsis, hypoxia, electrolyte abnormalities, hypovolemia, myocardial ischemia) while initiating treatment 1

Management Algorithm Based on Stability

UNSTABLE PATIENTS: Immediate Cardioversion

Perform immediate synchronized cardioversion for any tachycardia causing hemodynamic compromise. 1, 2

  • Sedate the patient if conscious and time permits 1, 2
  • For wide-complex tachycardia, presume ventricular tachycardia and cardiovert immediately 1, 2
  • Consider precordial thump only for witnessed, monitored unstable VT if defibrillator not immediately available 1, 2
  • Do not delay cardioversion to obtain a 12-lead ECG 1, 2

STABLE PATIENTS: Diagnostic Approach

Obtain a 12-lead ECG immediately—it is the single most critical diagnostic tool for identifying the tachycardia mechanism. 1

Step 1: Assess QRS Width

  • Narrow-complex (<120 ms): Supraventricular origin 1
  • Wide-complex (≥120 ms): Ventricular tachycardia until proven otherwise 1

Step 2: Assess Rhythm Regularity

  • Regular rhythm: AVNRT, AVRT, atrial flutter with fixed block, atrial tachycardia, or VT 1
  • Irregular rhythm: Atrial fibrillation, multifocal atrial tachycardia, or atrial flutter with variable block 1

Management of Stable NARROW-Complex Tachycardia

Regular Narrow-Complex SVT

Administer adenosine 6 mg rapid IV push followed by saline flush; if ineffective after 1-2 minutes, give 12 mg (may repeat once). 1

  • Vagal maneuvers (Valsalva, carotid massage) can be attempted first but should not delay adenosine 3, 1
  • Alternative agents if adenosine fails or is contraindicated: IV beta-blockers (metoprolol, esmolol) or non-dihydropyridine calcium channel blockers (diltiazem, verapamil) 1

P-Wave Analysis for Narrow-Complex Tachycardia

  • P-wave buried in or immediately after QRS (pseudo S wave in inferior leads, pseudo R' in V1): Typical AVNRT 1
  • P-wave in early ST segment (short RP interval): Orthodromic AVRT 1
  • P-wave closer to next QRS (long RP interval): Atypical AVNRT, PJRT, or atrial tachycardia 1

Irregular Narrow-Complex Tachycardia (Atrial Fibrillation/Flutter)

Use IV beta-blockers for ventricular rate control; non-dihydropyridine calcium channel blockers (diltiazem) are acceptable alternatives. 1

  • Anticoagulation as per guidelines is mandatory before cardioversion 3

Management of Stable WIDE-Complex Tachycardia

Treat all wide-complex tachycardia as ventricular tachycardia unless proven otherwise—administering verapamil or diltiazem for presumed SVT when the rhythm is actually VT can cause hemodynamic collapse or ventricular fibrillation. 1

ECG Features Diagnostic of Ventricular Tachycardia

AV dissociation (independent P-waves with ventricular rate faster than atrial rate) is pathognomonic for VT. 1

Other pathognomonic features:

  • Fusion or capture beats 1
  • Concordance (all QRS complexes positive or all negative across V1-V6) 1

ECG Features Highly Suggestive of VT

  • QRS duration >140 ms with RBBB morphology or >160 ms with LBBB morphology 1
  • RS interval >100 ms in any precordial lead 1
  • Prior myocardial infarction with first occurrence of wide-complex tachycardia after the infarct 1

Pharmacologic Management of Stable VT

Administer amiodarone 150 mg IV over 10 minutes, followed by maintenance infusion of 1 mg/min for the first 6 hours. 1

  • Alternative: Procainamide 20-50 mg/min until arrhythmia suppression, hypotension, QRS widening >50%, or maximum dose of 17 mg/kg; avoid in prolonged QT or heart failure 1

Diagnostic Use of Adenosine in Wide-Complex Tachycardia

Adenosine may be used for diagnosis of regular monomorphic wide-complex tachycardia of uncertain origin, but carries significant risks. 1

  • Can precipitate ventricular fibrillation in patients with coronary artery disease 1
  • May accelerate ventricular rate in pre-excited tachycardias (atrial fibrillation with WPW) 1
  • Never give adenosine for irregular or polymorphic wide-complex tachycardia 1, 2

Critical Pitfalls to Avoid

  • Never use AV nodal blocking agents (adenosine, calcium channel blockers, beta-blockers) in pre-excited atrial fibrillation or flutter—this can accelerate ventricular response and cause cardiac arrest 1, 2
  • Never delay cardioversion in unstable patients while obtaining 12-lead ECG 1, 2
  • Never normalize heart rate in compensatory tachycardia where cardiac output depends on the rapid rate (e.g., sepsis, hypovolemia) 1, 2
  • Never combine multiple AV nodal blocking agents with overlapping half-lives—this causes profound bradycardia 1, 2
  • Avoid sotalol in patients with prolonged QT interval 1

When to Initiate Workup

Heart rates ≥150 bpm typically indicate a primary tachyarrhythmia requiring immediate evaluation. 4

  • Below 150 bpm, tachycardia is more likely secondary to physiologic stress (fever, dehydration, pain, anxiety) unless ventricular dysfunction is present 4
  • Sinus tachycardia (>100 bpm) requires treatment of the underlying cause rather than specific antiarrhythmic therapy 1, 4
  • Heart rates <150 bpm are unlikely to cause symptoms unless ventricular function is impaired 1, 4

Indications for Urgent Cardiology/Electrophysiology Referral

  • Pre-excitation pattern (short PR, delta wave) on resting ECG with history of paroxysmal palpitations—indicates WPW syndrome with risk of sudden death 1, 2
  • Wide-complex tachycardia of unknown origin 1, 2
  • Any suspected ventricular tachycardia, even if self-terminated 2, 4
  • Recurrent regular paroxysmal palpitations with abrupt onset/termination 1, 2
  • Drug-resistant or drug-intolerant tachyarrhythmias 1, 2
  • Patients desiring definitive cure (catheter ablation) 1, 2

Additional Diagnostic Studies

  • Echocardiography to evaluate structural heart disease, especially in recurrent tachycardia 1
  • Ambulatory monitoring (Holter or event recorder) to capture paroxysmal episodes in patients with intermittent symptoms 1

References

1
Guideline

Initial Approach to Managing Tachycardia

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

2
Guideline

Initial Workup of Symptomatic Tachycardia

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

3
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

4
Guideline

Tachycardia Workup Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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