Inhalation of which agent can be used to decrease venous return and increase prolapse?

• A. Amyl Nitrite (vasodilator)
• B. Nitroglycerin
• C. Epinephrine
• D. Atropine

Answer: (A)

Mitral valve prolapse is more evident when the left ventricle has less filling, so reducing preload makes the prolapsing leaflets bulge more clearly. Inhaled amyl nitrite is a rapid-acting venodilator that quickly decreases venous return to the heart, lowering preload. This sudden drop in venous return exaggerates the prolapse of the mitral valve during systole, making it easier to detect on exam or with echocardiography. Other agents either don’t act as a fast venodilator or don’t reduce preload in the same way—nitroglycerin can lower preload but isn’t typically used as a provocative test for prolapse; epinephrine and atropine don’t produce this preload-reduction effect and may even counteract it.