What is the management for a patient with tachycardia (heart rate of 164 beats per minute)?

Management of Tachycardia at 164 bpm

The immediate priority is determining hemodynamic stability and identifying whether this is a narrow or wide complex tachycardia on ECG, as this fundamentally dictates whether you proceed to immediate synchronized cardioversion versus pharmacologic management. 1

Initial Assessment Algorithm

Step 1: Assess Hemodynamic Stability

• Check for signs of instability: acute altered mental status, ischemic chest pain, acute heart failure, hypotension, or shock 1
• If ANY of these are present and attributed to the tachycardia → proceed immediately to synchronized cardioversion 1
• Apply supplementary oxygen and establish IV access while evaluating 1

Step 2: Obtain 12-Lead ECG (if patient is stable)

• Determine QRS width: narrow (<120 ms) versus wide (≥120 ms) 1
• Assess regularity of rhythm 1
• Do not delay cardioversion in unstable patients to obtain ECG 1

Management Based on Rhythm Type

If Hemodynamically UNSTABLE (Regardless of Rhythm)

Immediate synchronized cardioversion is indicated 1, 2

• Initial energy: 50-100 J for SVT 1, 3
• Sedate if conscious and time permits 1
• If unable to synchronize, use unsynchronized high-energy shocks 1

If Hemodynamically STABLE with Narrow Complex (<120 ms)

Critical caveat: At 164 bpm with narrow complex, this could be sinus tachycardia, SVT, atrial flutter, or atrial fibrillation. The approach differs significantly 1.

For Regular Narrow Complex Tachycardia (likely SVT/AVNRT):

1. Vagal maneuvers first 2, 4

   • Modified Valsalva maneuver (supine, strain for 10-30 seconds at 30-40 mmHg) is 2.8-3.8 times more effective than standard technique 2
   • Success rate: 27.7% 2
   • Alternative: carotid sinus massage for 5-10 seconds (after confirming no carotid bruit) 2
   • Never apply pressure over eyeballs 2

2. If vagal maneuvers fail → Adenosine 6 mg IV rapid push 2, 4, 3

   • Success rate: 90-95% for SVT/AVNRT 2, 4
   • Follow immediately with saline flush through large vein 3
   • If no response after 1-2 minutes, give 12 mg IV rapid push 3
   • Have cardioversion equipment ready - adenosine can precipitate atrial fibrillation 2, 3
   • Side effects occur in ~30% but are brief (<1 minute) 2

3. If adenosine fails → IV beta-blockers or calcium channel blockers 1

   • Esmolol (preferred IV beta-blocker due to rapid onset) 1
   • IV diltiazem (preferred calcium channel blocker for safety/efficacy) 1
   • Metoprolol IV is alternative 1
   • Avoid in patients with heart failure, heart block, or pre-excitation 1, 5

For Irregular Narrow Complex (likely Atrial Fibrillation/Flutter):

• Rate control with IV beta-blockers, diltiazem, or verapamil 1
• Atrial flutter often more difficult to rate-control than AF 1
• If rate control fails, consider synchronized cardioversion 1

Important distinction: If this is sinus tachycardia (upper limit ~220 minus patient's age), do NOT treat the rate - identify and treat the underlying cause (fever, hypovolemia, anemia, hypoxia) 1. Normalizing heart rate when it's compensatory can be detrimental 1.

If Hemodynamically STABLE with Wide Complex (≥120 ms)

Assume ventricular tachycardia until proven otherwise 1

• If definitely supraventricular with aberrancy, manage as narrow complex SVT 1
• If uncertain or likely VT: IV procainamide or amiodarone 1
• Amiodarone preferred if impaired LV function or heart failure 1
• If pharmacologic therapy fails → synchronized cardioversion at 100 J initial energy 1

Critical Contraindications

Never give adenosine, verapamil, or diltiazem if:

• Pre-excited atrial fibrillation suspected (irregular wide complex) - can precipitate ventricular fibrillation 3
• Wide complex tachycardia of uncertain etiology 1

Avoid calcium channel blockers in:

• Systolic heart failure 3, 5
• Heart block or sinus node dysfunction without pacemaker 1
• Known pre-excitation syndromes 1

Post-Conversion Management

• Monitor for recurrence and premature complexes 3
• Refer all patients to electrophysiology/cardiology for definitive management 1, 2
• Catheter ablation is first-line definitive therapy with 94.3-98.5% success rate 2, 4
• If ablation declined: oral beta-blockers, diltiazem, or verapamil for long-term management (80-98% success) 2, 4