The physician has ordered nitroglycerin buccal tablets for a client with stable angina. The nurse knows that nitroglycerin affects the heart by:

Appeared in: DHS Staff Nurse - 2018 (Shift-2nd)

Explanation

Nitroglycerin is a potent vasodilator that relaxes the smooth muscle of blood vessels.
A key therapeutic action is the dilation of the large epicardial coronary arteries, which increases oxygenated blood flow to the heart muscle (myocardium).
This effect directly counteracts the ischemia (lack of oxygen) that causes the pain of stable angina.
While it also reduces preload and afterload, the dilation of coronary vessels is a direct and significant effect on the heart's blood supply.

Option A: Nitroglycerin does not slow heart contractions. The vasodilation it causes leads to a drop in blood pressure, which can trigger a compensatory reflex tachycardia (increased heart rate).
Option C: Nitroglycerin decreases venous return to the heart (preload) due to venodilation. This leads to a reduction in ventricular volume and filling, not an increase in fill time.
Option D: Nitroglycerin does not have a positive inotropic effect; it does not strengthen heart contractions. Its primary action is on vascular smooth muscle, not the heart muscle itself.

Clinical Relevance

Nursing practice connection: Use the key finding related to Pharmacology: Mechanism of Action of Nitroglycerin to guide bedside assessment, documentation, and the next nursing action.
When administering nitroglycerin, nurses must monitor the client's blood pressure closely for hypotension, a common side effect.
Headache is another very common side effect due to the dilation of cerebral blood vessels. The nurse should inform the client this is expected and usually subsides.
Patient education is critical: instruct the client to sit or lie down before taking sublingual nitroglycerin to prevent falls from potential dizziness or syncope.

How to Approach the Question

First, identify the core of the question: it asks for the mechanism of action of nitroglycerin on the heart.
Recall the drug class for nitroglycerin. It is a nitrate, which is a potent vasodilator.
Think about what 'vasodilator' means in the context of the heart. It means it widens blood vessels.
Evaluate the options based on this primary mechanism:
A) Slowing contractions is an effect of beta-blockers, not nitrates.
B) Dilating coronary blood vessels directly relates to vasodilation and improves oxygen supply to the heart.

Concept Tested & Keywords

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E6 Pharmacology Katzung 16e pp. 309-311, 305-307

E6 Medicine Harrison 22e Part 2 p. 5-7

Practise the full DHS Staff Nurse - 2018 (Shift-2nd)

Attempt every question from this paper in a timed mock, then review the full solution for each one.