Pre‑operative and Peri‑operative Management of Hypertension in Pheochromocytoma

Alpha‑adrenergic Blockade (First‑line Therapy)

• Start an oral α‑blocker immediately in any patient with suspected or confirmed pheochromocytoma who has paroxysmal or severe sustained hypertension. The goal is rapid blood‑pressure control before surgery. 1
• Recommended α‑blockers and typical dosing:
  
  • Phenoxybenzamine 10–20 mg 2–3 times daily
  • Prazosin 1–3 mg 2–3 times daily
  • Doxazosin 2–4 mg 2–3 times daily
  • Terazosin 2–10 mg twice daily
• Duration of α‑blockade: Continue for 10–14 days pre‑operatively to achieve target blood pressure and heart‑rate normalization. 1
• Alternative agents (if phenoxybenzamine unavailable): α‑methyldopa or clonidine may be used as adjuncts. 1

Beta‑blocker Use (Critical Timing)

• Avoid β‑blockers until adequate α‑blockade is established; initiating β‑blockade alone can precipitate a hypertensive crisis. 1
• Add β‑blockers only after successful α‑blockade when reflex tachycardia or arrhythmias persist. 1
• Intra‑operative arrhythmias: administer intravenous propranolol as needed. 1

Adjunctive Pharmacologic Therapies

• Metyrosine (tyrosine‑hydroxylase inhibitor) may be added (0.25–1 g four times daily) for additional catecholamine suppression when α‑blockade alone is insufficient. 1
• High‑sodium diet and aggressive volume replacement are essential to counteract catecholamine‑induced intravascular volume depletion and to prevent postoperative hypotension. 2
• Intravenous fluid bolus should be given immediately before tumor resection to ensure adequate preload. 1

Management of Hypertensive Crises

• Keep intravenous phenoxybenzamine (or phentolamine) readily available and administer promptly for any intra‑operative or pre‑operative hypertensive emergency. 1

Special Clinical Situations

Tumors Producing Only Dopamine

• Do not give pre‑operative medical therapy for pheochromocytomas that secrete exclusively dopamine (identified by isolated plasma metanephrine elevation); these patients are usually normotensive or hypotensive. 3

Pregnancy

• Early pregnancy: if termination is chosen, perform under combined α‑ and β‑blockade followed immediately by tumor resection.
• Late pregnancy: maintain α‑ and β‑blockade, schedule elective cesarean delivery, then proceed with tumor removal. (Both strategies rely on adequate adrenergic blockade.) 1

Metastatic or Inoperable Disease

• Blood‑pressure control: use α‑blockade (any of the agents above) plus β‑blockade and/or metyrosine as needed. 1
• Systemic therapy options: cyclophosphamide + vincristine + dacarbazine chemotherapy; high‑dose ^131I‑MIBG radionuclide therapy can provide moderate tumor response and aid hypertension control. 4

Post‑operative Monitoring

• Monitor blood pressure, heart rate, and glucose in the immediate postoperative period; adjust antihypertensive regimen accordingly. 2
• Measure plasma or urinary metanephrines during follow‑up to detect residual or recurrent disease. 2
• Perform annual biochemical testing lifelong to surveil for recurrence or metastasis. 2

Common Pitfalls to Avoid

• Never start β‑blockers before adequate α‑blockade; this can cause unopposed vasoconstriction and severe hypertensive crisis. 1
• Do not underestimate the need for volume replacement; catecholamine‑driven volume depletion is significant and requires aggressive fluid resuscitation. 2
• Avoid drugs that can trigger catecholamine release in patients without proper adrenergic blockade. 3

Definitive Treatment

• Surgical resection is curative for benign pheochromocytoma and remains the standard of care. 1
• Laparoscopic adrenalectomy is preferred over open surgery for most tumors, except when the mass is very large. 1
• Multidisciplinary surgical planning (surgeons, endocrinologists, intensivists, anesthesiologists) with expertise in pheochromocytoma management is essential for optimal outcomes. 1

Pre‑operative and Intra‑operative Management of Pheochromocytoma: α‑Blockade, Adjuncts, and Pitfalls

First‑Line α‑Blockade (Prazosin)

• The Canadian cardiology guidelines recommend prazosin as the first‑line agent for pre‑operative blood‑pressure control in patients with suspected or confirmed pheochromocytoma【5】.
• Initiate prazosin at 1–3 mg orally 2–3 times daily and titrate to achieve target blood pressure and heart‑rate goals【5】.
• Continue prazosin for 10–14 days before surgery to normalize blood pressure and heart rate, thereby reducing the risk of intra‑operative hypertensive crises【5】.
• Adequate α‑blockade with prazosin helps reverse catecholamine‑induced intravascular volume depletion and prevents intra‑operative crises【6】.

Alternative α‑Blockers

• Phenoxybenzamine (10–20 mg 2–3 times daily) and doxazosin (2–4 mg 2–3 times daily) are acceptable alternatives; however, phenoxybenzamine may provide superior control compared with doxazosin【5】.

β‑Blocker Use

• β‑blockers must not be started before adequate α‑blockade is established, as unopposed α‑receptor stimulation can precipitate life‑threatening hypertensive crises【5】【6】.
• β‑blockers may be added only after sufficient α‑blockade if reflex tachycardia or arrhythmias persist【5】.

Volume Management (Pre‑operative)

• A high‑sodium diet combined with aggressive oral fluid intake is recommended to correct catecholamine‑induced intravascular volume contraction【6】.
• An intravenous fluid bolus administered immediately before tumor resection ensures adequate preload and helps prevent postoperative hypotension【5】.

Adjunctive Pharmacotherapy

• If α‑blockade alone does not achieve target hemodynamics, metyrosine (0.25–1 g four times daily) can be added as a tyrosine‑hydroxylase inhibitor【5】.

Intra‑operative Pharmacologic Strategies

• Intravenous phentolamine should be readily available and is the first‑line agent for acute hypertensive crises during tumor manipulation (e.g., systolic BP > 200 mmHg)【5】.
• Intravenous nitroglycerin is not recommended for pre‑operative blood‑pressure control but may be used intra‑operatively as an adjunct for acute hypertension when needed【5】【6】.
• Propranolol may be employed for intra‑operative arrhythmias only after adequate α‑blockade has been achieved【5】.

Post‑operative Monitoring

• Monitor blood pressure, heart rate, and glucose continuously for the first 24–48 hours after tumor removal to detect hypotension, rebound hypertension, arrhythmias, and hypoglycemia【6】.
• In patients undergoing bilateral adrenalectomy or cortical‑sparing procedures, assess for adrenal insufficiency and provide appropriate steroid replacement if needed【6】.

Contra‑indicated or Non‑recommended Therapies

• Clonidine, although listed as an alternative antihypertensive in some guidelines, has no therapeutic effect for pheochromocytoma‑induced hypertension and should be avoided in favor of α‑blockers【5】.
• Nitroglycerin lacks guideline support for pre‑operative blood‑pressure management and should be reserved solely for intra‑operative hypertensive emergencies【5】【6】.

All facts are derived from cited references (@1–@4) and reflect the current recommendations of Canadian cardiology/endocrinology guideline societies.