How to manage supraventricular tachycardia (SVT) in a patient with an Addisonian crisis?

Managing SVT in Addisonian Crisis

Immediately correct the underlying adrenal insufficiency with high-dose intravenous hydrocortisone (100-200 mg IV bolus) while simultaneously managing the SVT according to standard hemodynamic stability-based algorithms, as the tachycardia is likely precipitated or exacerbated by the crisis itself. 1

Critical First Steps: Address Both Conditions Simultaneously

The Addisonian crisis is the primary driver of hemodynamic instability and must be treated aggressively alongside the arrhythmia:

• Administer 100-200 mg hydrocortisone IV immediately as a bolus, followed by continuous infusion or repeated dosing (50-100 mg every 6-8 hours), as patients in Addisonian crisis during acute stress require substantially higher doses than standard supplementation 1
• Provide aggressive volume resuscitation with normal saline (1-2 liters rapidly), as these patients are profoundly volume depleted and hypotensive from mineralocorticoid deficiency 1
• Correct electrolyte abnormalities, particularly hyperkalemia and hyponatremia, which are hallmarks of adrenal crisis and can independently affect cardiac rhythm 1

SVT Management Algorithm Based on Hemodynamic Status

If Hemodynamically Unstable (Hypotension, Altered Mental Status, Shock, Chest Pain, Acute Heart Failure):

• Proceed directly to synchronized cardioversion (50-100J initial energy for SVT), which achieves 100% conversion in hemodynamically unstable patients 2, 3, 4
• Do not delay for pharmacologic interventions when the patient shows signs of instability 3, 4

If Hemodynamically Stable Despite Crisis:

Step 1: Vagal Maneuvers

• Attempt modified Valsalva maneuver first (31-43% success rate) 3, 4, 5
• This is safe, quick, and may avoid need for medications in an already complex clinical scenario 4

Step 2: Adenosine Administration

• Give adenosine 12 mg IV rapid bolus (not 6 mg) through a proximal large vein, followed immediately by saline flush 3, 6
• Recent evidence shows 12 mg initial dose has significantly higher conversion rate than 6 mg (54.2% vs 40.6%, p=0.03) 6
• Achieves 90-95% effectiveness for AVNRT and AVRT 2, 3, 4
• If unsuccessful, may repeat with second 12 mg dose 2

Step 3: Alternative Pharmacologic Agents

• IV beta-blockers (metoprolol or esmolol) are preferred in this setting over calcium channel blockers, given the hemodynamic fragility of Addisonian crisis 2, 3
• IV diltiazem or verapamil (64-98% success rate) can be used if beta-blockers contraindicated, but exercise extreme caution given potential for further hypotension 2, 3

Critical Pitfalls to Avoid in This Scenario

Do not assume the SVT is the primary problem - the Addisonian crisis is driving the clinical picture and the tachycardia may resolve once cortisol and volume are repleted 1

Avoid AV nodal blocking agents if any possibility of pre-excited atrial fibrillation (irregular rhythm, wide QRS complexes), as adenosine, diltiazem, verapamil, or beta-blockers can precipitate ventricular fibrillation in this setting 3

Obtain 12-lead ECG during tachycardia to confirm regular SVT and exclude ventricular tachycardia or pre-excited AF before administering any AV nodal blockers 3, 4

Monitor for worsening hypotension with any pharmacologic intervention, as these patients have minimal hemodynamic reserve due to their adrenal insufficiency 1

Ongoing Monitoring and Definitive Management

• Continue stress-dose steroids for 24-48 hours with gradual taper as clinical condition improves 1
• Arrange cardiology follow-up for consideration of catheter ablation (94.3-98.5% single-procedure success rate) to prevent recurrence once the acute crisis resolves 4, 5
• Heightened awareness and close monitoring are essential, as patients with adrenal insufficiency undergoing acute stress can decompensate rapidly despite initial stabilization 1