How to manage a 37-year-old with palpitations and tachycardia?

Management of 37-Year-Old with Palpitations and Heart Rate 200 bpm

Immediately assess hemodynamic stability and prepare for synchronized cardioversion if the patient shows signs of shock, altered mental status, chest pain, acute heart failure, or hypotension—these are life-threatening emergencies requiring electrical cardioversion without delay. 1

Immediate Assessment and Stabilization

Determine if the patient is stable or unstable:

• Unstable signs include systolic BP ≤90 mmHg, chest pain, heart failure, altered mental status, or signs of shock 1
• At a rate of 200 bpm, this tachycardia is causing significant cardiovascular stress and warrants urgent intervention 1
• Provide supplementary oxygen, attach cardiac monitor, establish IV access, and obtain 12-lead ECG—but do not delay cardioversion if the patient is unstable 1

If Patient is Hemodynamically Unstable:

Proceed immediately to synchronized cardioversion 1:

• Sedate the patient if conscious (do not delay if extremely unstable) 1
• For narrow-complex SVT: start with 50-100 J biphasic, increase stepwise if unsuccessful 1
• For wide-complex regular tachycardia (monomorphic VT): start with 100 J, increase stepwise 1
• If unable to synchronize, use unsynchronized high-energy shocks 1

If Patient is Hemodynamically Stable:

Step 1: Obtain 12-Lead ECG Immediately

The ECG will determine your entire management pathway 1, 2:

• Narrow-complex tachycardia (QRS <0.12 sec): Most likely supraventricular tachycardia (AVNRT, AVRT, atrial flutter, or atrial fibrillation) 1
• Wide-complex tachycardia (QRS ≥0.12 sec): Assume ventricular tachycardia until proven otherwise—never give verapamil or adenosine for wide-complex tachycardia of uncertain origin 3
• Look for pre-excitation (delta waves): If present with irregular rhythm, this suggests atrial fibrillation with WPW—absolutely contraindicated to give AV nodal blockers (adenosine, verapamil, beta-blockers) as this can precipitate ventricular fibrillation 1, 3

Step 2: For Narrow-Complex Regular Tachycardia (Likely AVNRT/AVRT):

First-line: Vagal maneuvers 1:

• Valsalva maneuver: Have patient bear down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) in supine position 1
• Carotid sinus massage: Apply steady pressure for 5-10 seconds after confirming no carotid bruit 1
• Ice-cold wet towel to face (diving reflex) 1
• Success rate approximately 28% when switching between techniques 1

If vagal maneuvers fail—Adenosine is the drug of choice 1:

• Give 6 mg rapid IV bolus followed immediately by saline flush 1
• If no effect after 1-2 minutes, give 12 mg 1
• Can repeat 12 mg once more if needed 1
• Terminates AVNRT in approximately 95% of cases 1
• Contraindications: Asthma (can cause bronchospasm), known WPW with atrial fibrillation 1, 3
• Common side effects: Flushing, chest pain lasting <60 seconds, transient complete heart block 1
• Must be given in monitored environment 1

If adenosine fails or is contraindicated—IV AV nodal blockers 1:

• IV metoprolol or other beta-blocker (Class IIa recommendation) 1, 4
• IV diltiazem 5-10 mg over 60 seconds or IV verapamil 5-10 mg over 60 seconds (Class IIa) 1
• Critical warning: Never combine IV beta-blockers with IV calcium channel blockers—risk of profound bradycardia and hypotension 1, 4
• Verapamil contraindications: Severe hypotension, heart failure, 2nd/3rd degree AV block, sick sinus syndrome, WPW with atrial fibrillation, wide-complex tachycardia, concurrent beta-blocker use 3

If all pharmacologic measures fail—Synchronized cardioversion 1:

• 50-100 J for SVT, increase stepwise 1

Step 3: For Wide-Complex Tachycardia:

Assume ventricular tachycardia and never give verapamil or adenosine 3:

• If stable: IV amiodarone 300 mg over 1 hour (5 mg/kg) 1
• If unstable or refractory: Synchronized cardioversion starting at 100 J 1
• Urgent cardiology consultation required 2

Critical Pitfalls to Avoid:

• Never use verapamil for wide-complex tachycardia—can cause marked hemodynamic deterioration and ventricular fibrillation 3
• Never use AV nodal blockers (adenosine, verapamil, beta-blockers) in WPW with atrial fibrillation—can precipitate ventricular fibrillation by allowing rapid conduction down the accessory pathway 3, 1
• Do not assume sinus tachycardia at rate 200 in a 37-year-old—maximum predicted sinus rate is approximately 183 bpm (220 minus age), so this is likely a true tachyarrhythmia 1
• Do not delay cardioversion in unstable patients to obtain labs or additional testing 1
• Do not rely on automatic ECG interpretation—manually review the rhythm 1, 2

Post-Conversion Management:

Once rhythm is controlled, identify and treat underlying/precipitating causes 1, 2:

• Check TSH (hyperthyroidism), electrolytes (hypokalemia, hypomagnesemia), complete metabolic panel 2, 5
• Assess for stimulant use: caffeine, alcohol, nicotine, recreational drugs, medications 2
• Obtain echocardiogram to exclude structural heart disease 1, 2
• Mandatory cardiology/electrophysiology referral for: documented SVT at rate 200, any wide-complex tachycardia, pre-excitation on ECG, recurrent episodes, or patient preference to avoid lifelong medication 1, 2

Catheter ablation has >95% success rate with <1% risk of heart block and is potentially curative for AVNRT/AVRT—strongly consider referral rather than lifelong pharmacotherapy in a 37-year-old 2