What should be part of my initial workup for newly diagnosed (NYD) tachycardia?

Initial Workup for Newly Diagnosed Tachycardia

The initial workup for tachycardia NYD should include a 12-lead ECG, assessment of vital signs including orthostatic blood pressure measurements, focused history for pattern and triggers, physical examination during tachycardia if possible, basic laboratory tests, and chest radiography. 1

Step 1: Initial Assessment and Stabilization

• Assess for signs of hemodynamic instability:

  • Altered mental status
  • Hypotension
  • Acute heart failure
  • Ischemic chest discomfort
  • Signs of shock

• Provide supplemental oxygen if:

  • Oxygen saturation is low
  • Patient shows increased work of breathing (tachypnea, retractions) 1

• Establish IV access and continuous cardiac monitoring

Step 2: 12-Lead ECG Documentation

• Obtain a 12-lead ECG during tachycardia if possible 1
• Classify the tachycardia based on:
  • QRS width (narrow <0.12 sec vs. wide ≥0.12 sec)
  • Regularity (regular vs. irregular)
  • Rate (typically >100 beats/min) 1

Step 3: Focused History

Obtain specific information about:

• Pattern: number of episodes, duration, frequency
• Mode of onset and termination (sudden vs. gradual)
• Possible triggers 1
• Associated symptoms (syncope, chest pain, dyspnea)
• Response to vagal maneuvers (suggests AVNRT or AVRT)
• Family history of sudden death or arrhythmias 1

Step 4: Physical Examination

• Vital signs including orthostatic blood pressure measurements
• Cardiovascular examination for:
  • Irregular pulse
  • Irregular jugular venous pulsations
  • Variation in S1 intensity
  • Signs of structural heart disease 1
• Look for signs of hyperthyroidism, anemia, infection, or volume loss 1

Step 5: Laboratory Testing

• Complete blood count
• Serum electrolytes
• Renal and hepatic function tests
• Thyroid function tests 1
• Consider D-dimer if pulmonary embolism is suspected (though specificity is limited in post-surgical patients) 2

Step 6: Additional Diagnostic Testing

• Chest radiography 1
• Transthoracic echocardiography to:
  • Detect underlying structural heart disease
  • Assess cardiac function
  • Evaluate atrial size 1

Special Considerations

For Post-Surgical Patients

• Consider pulmonary embolism as a potentially life-threatening cause
• CT angiography should be performed promptly if PE is suspected
• Avoid attributing tachycardia solely to pain or anxiety 2

For Narrow Complex Tachycardias

• If pre-excitation is present on resting ECG with history of paroxysmal regular palpitations, refer to arrhythmia specialist 1
• For irregular narrow complex tachycardias, consider atrial fibrillation, atrial flutter, or multifocal atrial tachycardia 1

For Wide Complex Tachycardias

• Always consider ventricular tachycardia first, especially with history of heart disease 3
• Look for AV dissociation, QRS duration >0.16 seconds, and QRS axis between -90 and +180 degrees 3

When to Refer to a Cardiac Arrhythmia Specialist

• Presence of wide complex tachycardia of unknown origin
• Clear history of paroxysmal regular palpitations
• Pre-excitation on resting ECG with history of paroxysmal palpitations
• Drug resistance or intolerance
• Patient preference to be free of drug therapy 1

Common Pitfalls to Avoid

• Relying on automatic ECG analysis systems (often unreliable) 1
• Attributing tachycardia solely to benign causes without considering serious etiologies 2
• Failing to document the arrhythmia during symptoms 4
• Delaying definitive imaging when pulmonary embolism is suspected 2

By following this systematic approach, you can effectively evaluate newly diagnosed tachycardia and determine the appropriate next steps for management.