Why is nitroglycerin contraindicated when hypotension is present?

• A. It can cause dangerous drops in blood pressure and worsen perfusion
• B. It reduces heart rate
• C. It raises blood pressure
• D. It improves renal perfusion

Answer: (A)

Nitroglycerin is a potent vasodilator that lowers preload by dilating veins and, at higher doses, lowers afterload as well. In a patient who is already hypotensive, this additional vasodilation can cause the blood pressure to fall even further, reducing perfusion to vital organs including the brain, kidneys, and heart. That drop in perfusion can lead to worsening shock and organ ischemia. It can also lower diastolic pressure, which reduces coronary perfusion pressure and can worsen myocardial ischemia when blood pressure is already low. For these reasons nitroglycerin is contraindicated in hypotension. It does not raise blood pressure; it may trigger reflex tachycardia, and it does not improve renal perfusion.