Florida State Paramedic Practice Exam

Which therapeutic effect does nitroglycerin have in myocardial infarction?

1. Increases heart contractility

2. Decreases myocardial oxygen demand

3. Increases heart rate

4. Prevents clot formation

The correct answer is: Decreases myocardial oxygen demand

Nitroglycerin is a vasodilator primarily used in the management of angina and myocardial infarction. It helps to alleviate the symptoms of ischemia by dilating blood vessels, which reduces the workload on the heart. This vasodilatory effect significantly decreases myocardial oxygen demand by lowering both preload and afterload. By decreasing preload, nitroglycerin reduces the volume of blood returning to the heart, which leads to less exertion for the heart during each contraction. Similarly, by reducing afterload, it decreases the resistance the heart must work against to eject blood. As a result, the overall oxygen requirement of the heart muscle is lowered, helping to alleviate the strain during a myocardial infarction when the heart is already under distress due to inadequate blood supply. The other options do not reflect the primary therapeutic effect of nitroglycerin in this context. While the increase in heart rate, increase in contractility, and prevention of clot formation are important aspects of cardiac function and treatment in various scenarios, they are not the direct therapeutic effects associated with nitroglycerin during a myocardial infarction. Thus, the reduction of myocardial oxygen demand stands out as the most relevant therapeutic effect in this situation.