What is a contraindication when using amyl nitrite?

• A. Severe Aortic Stenosis
• B. Hypotension
• C. Pulmonary Edema
• D. Asthma

Answer: (A)

Amyl nitrite works by rapidly dilating veins and some arteries, which lowers preload and afterload and can cause a quick drop in blood pressure. In severe aortic stenosis, the left ventricle already struggles to push blood through the narrowed aortic valve, so it relies on maintaining adequate preload to sustain cardiac output. Reducing preload with amyl nitrite can cause a dangerous drop in stroke volume and cardiac output, leading to syncope or shock. That combination makes severe aortic stenosis a contraindication.

Hypotension is also a contraindication because any further BP drop is hazardous, but the scenario with fixed outflow obstruction from severe AS is particularly problematic due to the reliance on preload to maintain flow. Asthma and pulmonary edema are not classic contraindications for amyl nitrite.