How to manage broad complex tachycardia in a patient with pheochromocytoma?

Management of Broad Complex Tachycardia in Pheochromocytoma

Critical First Principle: Never Use Beta-Blockers Alone

In pheochromocytoma, beta-blockers must ONLY be given in combination with an alpha-blocker, and only after the alpha-blocker has been initiated, as administration of beta-blockers alone has been associated with paradoxical increase in blood pressure from attenuation of beta-mediated vasodilation in skeletal muscle. 1

Immediate Assessment and Stabilization

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

• Proceed immediately to synchronized cardioversion without delay for pharmacologic therapy. 2, 3, 4
• Sedate with etomidate 0.2-0.3 mg/kg IV if conscious and time permits. 3, 4
• Have defibrillator at bedside with pads applied. 4
• Do not delay cardioversion to obtain additional diagnostic studies or attempt pharmacologic conversion. 3

If Hemodynamically Stable

Proceed with the pharmacologic approach below, but maintain continuous monitoring and be prepared for immediate cardioversion if the patient deteriorates. 3

Pharmacologic Management Algorithm for Stable Broad Complex Tachycardia

Step 1: Initiate Alpha-Blockade FIRST

• Start with phentolamine (competitive alpha-blocker) as the primary agent for pheochromocytoma-related tachyarrhythmias. 2
• Alternative options include nicardipine or urapidil, which have been successfully used in perioperative management of pheochromocytoma. 2
• Phenoxybenzamine (non-selective alpha-blocker) can be used but requires gradual dose escalation over 7-14 days, making it less suitable for acute management. 2

Step 2: Antiarrhythmic Therapy

Once alpha-blockade is established, consider antiarrhythmic agents based on the rhythm characteristics:

For Regular Monomorphic Wide Complex Tachycardia:

• Procainamide is the preferred first-line agent (Class IIa) if no severe heart failure or acute MI is present. 2, 3
• Amiodarone 150 mg IV over 10 minutes is preferred if severe heart failure or acute MI is present. 2, 3, 4
• Sotalol 1.5 mg/kg IV over 5 minutes is an alternative (Class IIb), but avoid if QT is prolonged. 2, 4

For Polymorphic Wide Complex Tachycardia:

• If QT interval is prolonged (torsades de pointes): IV magnesium is the primary treatment. 3
• If QT interval is normal and ischemia is suspected: IV amiodarone may be effective. 2

Step 3: Consider Diagnostic Adenosine (Only if Stable and Regular Rhythm)

• IV adenosine may be considered for undifferentiated regular stable wide complex tachycardia as it is relatively safe and can help diagnose the underlying rhythm. 2, 3
• Do NOT give adenosine for unstable, irregular, or polymorphic wide complex tachycardia as it may cause degeneration to ventricular fibrillation. 2

Critical Medications to AVOID in Pheochromocytoma

Absolutely Contraindicated:

• Labetalol (combined alpha/beta-blocker) has been associated with acceleration of hypertension in pheochromocytoma patients. 2
• Verapamil and diltiazem are contraindicated for wide complex tachycardia unless definitively proven to be supraventricular in origin, as they can cause hemodynamic collapse. 2, 3
• Pure beta-blockers (esmolol, propranolol, metoprolol) should never be used alone in pheochromocytoma. 1

Use with Extreme Caution:

• Beta-blockers should be avoided in hypotensive states. 3, 4
• If beta-blockade is absolutely necessary for rate control after adequate alpha-blockade, use beta-1 selective agents (esmolol preferred for titratability). 2

Supportive Management

Electrolyte Correction:

• Rapidly correct potassium, magnesium, and calcium abnormalities, as these are crucial in all patients with wide complex tachycardia. 3, 4

Monitoring:

• Continuous cardiac monitoring with telemetry. 4
• Blood pressure monitoring every 5 minutes until stable. 4
• Serial 12-lead ECGs (baseline, post-intervention, then every 4-6 hours). 4

Fluid Management:

• High-sodium diet and 1-2 liters of saline 24 hours prior to any intervention to reduce risk of hypotension. 2
• Use compressive stockings to prevent orthostatic hypotension. 2

Post-Stabilization Care

• All patients require ICU/CCU admission and immediate cardiology/electrophysiology consultation. 3, 4
• Consider electrophysiology study and possible ablation once stabilized. 3, 4
• Definitive surgical management of pheochromocytoma should be planned after adequate preoperative alpha-blockade for at least 7-14 days. 2

Special Clinical Scenarios

If Concurrent Thyrotoxic Crisis:

• More intensive cardiovascular management may be required, but alpha-blockade must still precede beta-blockade even though this differs from standard thyrotoxic crisis management. 5
• Small doses of doxazosin and carvedilol can be used together under intensive monitoring. 5

If Cardiogenic Shock:

• Consider extracorporeal life support (ECLS) as a bridge to definitive therapy if refractory to medical management. 6
• Embolization of the adrenal artery during ECLS may stabilize patients as a bridge to surgery. 6