Pharmacology Myocardial Infarction Meds #4

Question

Which describes the function(s) of nitroglycerin during a myocardial infarction? Select all that apply.

Answers

  1. Increases preload
    • Rationale:

      This answer is not correct because nitrates, such as nitroglycerin, decreases (not increases) preload. By decreasing preload, nitroglycerin decreases myocardial blood volume, pressure, and myocardial muscle wall tension. This reduces myocardial oxygen consumption.

  2. Decrease afterload
    • Rationale:

      This answer is correct because nitroglycerin dilates all blood vessels, which reduces peripheral resistance, preload, and afterload. This reduces tension on the myocardium, which reduces myocardial workload and oxygen consumption.

  3. Produces vasodilation
    • Rationale:

      This answer is correct because nitroglycerin vasodilates (dilates all blood vessels), which reduces peripheral resistance, preload, and afterload. This reduces tension on the myocardium, which reduces myocardial workload and oxygen consumption.

  4. Decreases catecholamines
    • Rationale:

      This answer is not correct because nitroglycerin does not decrease catecholamines. Beta blockers block and reduce catecholamines, decreasing their impact on the body and heart.

  5. Produces peripheral constriction
    • Rationale:

      This answer is not correct because nitroglycerin dilates all blood vessels. In higher doses, this decreases resistance in vessels and decreases afterload. All of this decreases the workload and oxygen consumption

Overview

Nitroglycerin is an antianginal medication and an antihypertensive medication. The medication’s action is to vasodilate, thereby decreasing the workload, oxygen consumption, which hopefully decreases angina and further damage to the myocardium during myocardial infarction.

Explanation

Learning Outcomes

Nitroglycerin’s function is to dilate blood vessels. This function makes this medication useful to lower the blood pressure, decrease angina, and hopefully minimize further damage to the myocardium during myocardial infarction. Nitroglycerin can be administered in various routes, including sublingual, nasal spray, and intravenous routes. The blood pressure should be carefully monitored during administration due to its profound ability to vasodilate, therefore cause intense hypotension. The life-saving, heart preserving action of this medication makes it a priority drug during treatment of acute angina and myocardial infarction.

Test Taking Tip

When trying to understand nitroglycerin, think nitrO (large O). This stands for hypOtension or vasOdilation of the blood vessel.

Video Rationale