A patient with hypertrophic obstructive cardiomyopathy (HOCM) develops intraoperative hypotension with a dynamic outflow gradient. Which intervention is MOST appropriate?

• A Administer epinephrine 10 mcg IV bolus
• B Dopamine infusion to maintain cardiac output
• C Nitroglycerine infusion to reduce preload and LV wall tension
• D IV phenylephrine and volume loading; avoid tachycardia and vasodilation ✓

Explanation

In HOCM, hypotension usually reflects worsening of dynamic LVOT obstruction. The obstruction is exacerbated by decreased preload, decreased afterload, and tachycardia. Phenylephrine (pure alpha-1 agonist) restores systemic vascular resistance and raises diastolic pressure without causing tachycardia, thereby reducing the outflow gradient. Volume loading increases preload. Epinephrine causes tachycardia and vasodilation, both catastrophic in HOCM. Dopamine and nitroglycerine similarly worsen outflow obstruction. Beta-blockers and esmolol are definitive pharmacological treatments for acute HOCM crises.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.