What is the management approach for a patient with a heart rate in the 140s, indicating tachycardia?

Management of Heart Rate in the 140s

For a patient with heart rate in the 140s, immediately assess hemodynamic stability—if unstable (hypotension, chest pain, altered mental status, acute heart failure), proceed directly to synchronized cardioversion; if stable, determine if the rhythm is narrow or wide complex on ECG and treat the underlying cause rather than the rate itself if sinus tachycardia is present. 1

Initial Assessment and Stabilization

Hemodynamic Status Determines Urgency:

• If the patient shows signs of shock, altered mental status, chest pain, acute heart failure, or hypotension attributable to the tachycardia, proceed immediately to synchronized cardioversion without delay 1
• For hemodynamically unstable atrial fibrillation/flutter, use synchronized cardioversion with 200 J for atrial fibrillation or 50 J for flutter, preceded by brief anesthesia when possible 2
• Attach cardiac monitor, establish IV access, obtain 12-lead ECG, but do not delay cardioversion if unstable 1

Identify Reversible Causes:

• Provide supplemental oxygen if signs of respiratory distress or inadequate oxygenation are present, as hypoxemia commonly causes tachycardia 1
• Treat underlying causes: fever, anemia, hypotension, dehydration, hypoxia 1

Determine the Rhythm Type

Narrow vs. Wide Complex QRS:

• Obtain 12-lead ECG to differentiate narrow complex (<120 ms) from wide complex (>120 ms) tachycardia 2
• Wide complex tachycardia should be treated as ventricular tachycardia unless proven otherwise 2

Management Based on Rhythm

Sinus Tachycardia (Critical Pitfall)

Do NOT treat the heart rate directly in sinus tachycardia—this is physiologic and requires identification and treatment of the underlying cause (fever, anemia, hypotension, dehydration, hypoxia). 1

• The upper limit of sinus tachycardia is approximately 220 minus the patient's age 1
• In patients with poor cardiac function, cardiac output depends on rapid heart rate, and "normalizing" the rate can be detrimental 1

Supraventricular Tachycardia (SVT) - Narrow Complex, Regular

First-Line: Vagal Maneuvers

• Attempt Valsalva maneuver or carotid sinus massage first, with approximately 28% success rate 3
• For reentrant paroxysmal SVT, carotid sinus massage should be the initial intervention 2

Second-Line: Adenosine

• If vagal maneuvers fail, administer adenosine 6 mg rapid IV push followed by saline flush 1, 3
• If no response, give 12 mg IV after 1-2 minutes; may repeat 12 mg dose if needed 2, 1
• Adenosine terminates approximately 95% of AVNRT cases and has minimal sustained hemodynamic effects due to very short half-life 3
• Caution: Use adenosine with care when diagnosis is unclear—it may produce ventricular fibrillation in patients with coronary artery disease and rapid ventricular rate in pre-excited tachycardias 2

Alternative Agents if Adenosine Fails:

• IV beta-blockers: metoprolol 2.5-5.0 mg every 2-5 minutes to total of 15 mg over 10-15 minutes, or atenolol 2.5-5.0 mg over 2 minutes to total of 10 mg 2
• IV diltiazem: 20 mg (0.25 mg/kg) over 2 minutes followed by infusion of 10 mg/h 2

Atrial Fibrillation/Flutter with Rapid Ventricular Response

For Hemodynamically Stable Patients:

• Initiate rate control medications promptly rather than waiting for spontaneous conversion 4
• First-line agents: Beta-blockers (metoprolol, esmolol) or non-dihydropyridine calcium channel blockers (diltiazem, verapamil) 4
• Target resting heart rate <110 bpm as initial goal (lenient control) 4
• For ongoing ischemia without hemodynamic compromise, beta-blockers are preferred unless contraindicated 2

For Hemodynamically Unstable Patients:

• Synchronized cardioversion is indicated when AFib with RVR is associated with symptomatic hypotension, angina, or heart failure 4

Special Considerations:

• In patients with heart failure and AFib with RVR, use beta-blockers with caution; amiodarone may be preferred 4
• For episodes not responding to electrical cardioversion or recurring after brief sinus rhythm, use IV amiodarone for rate control 2
• IV digoxin is appropriate for rate control principally in patients with severe LV dysfunction and heart failure 2

Wide Complex Tachycardia (Presumed Ventricular Tachycardia)

If Hemodynamically Stable:

• Amiodarone is first-line: 150 mg IV over 10 minutes, followed by maintenance infusion of 1 mg/min for first 6 hours, then 0.5 mg/min 2, 1
• Alternative: Lidocaine bolus 1.0-1.5 mg/kg, with supplemental boluses of 0.5-0.75 mg/kg every 5-10 minutes to maximum 3 mg/kg, followed by infusion of 2-4 mg/min 2
• Procainamide: 20-30 mg/min loading infusion up to 12-17 mg/kg, followed by infusion of 1-4 mg/min 2

If Hemodynamically Unstable:

• Immediate unsynchronized cardioversion for polymorphic VT (200 J) 2
• Synchronized cardioversion for monomorphic VT with rates >150 bpm (100 J) 2

Critical Pitfalls to Avoid

Wolff-Parkinson-White Syndrome:

• Never use AV nodal blocking agents (beta-blockers, calcium channel blockers, digoxin, adenosine) in patients with WPW and wide-complex tachycardia—they can accelerate ventricular rate and precipitate ventricular fibrillation 1
• Use IV procainamide or ibutilide instead 4

Compensatory Tachycardia:

• Do not aggressively treat compensatory tachycardia in patients with poor cardiac function or shock, as stroke volume is limited and cardiac output depends on the elevated heart rate 1

Beta-Blocker and Calcium Channel Blocker Warnings:

• Metoprolol can cause bradycardia, heart block, and cardiac arrest; monitor heart rate and rhythm closely 5
• Avoid verapamil or diltiazem in suspected ventricular tachycardia or pre-excited atrial fibrillation, as they may cause hemodynamic collapse 3
• Beta-blockers may mask tachycardia in hypoglycemia and should be used with caution in bronchospastic disease 5