If coronary vasospasm is suspected during catheterization, what is the expected effect of vasodilator administration?

• A. Induction of spasm.
• B. Relief of spasm and improved vessel caliber.
• C. No effect on caliber.
• D. Causes vasoconstriction.

Answer: (B)

When a coronary artery is in spasm, its smooth muscle contracts and narrows the lumen. A vasodilator relaxes that smooth muscle, counteracting the spasm. In the cath lab, giving a vasodilator like nitroglycerin typically causes the spasm to resolve, so the vessel dilates and the caliber improves, with better blood flow evident on angiography. If the vasospasm truly exists, you’ll see prompt dilatation after administration. If there’s no change, it likely isn’t vasospasm but a fixed atherosclerotic stenosis. Vasodilators do not cause spasm; they relieve it and widen the vessel.