Which of the following drugs is used in MI ?
**Core Concept**
Nitroglycerin is a vasodilator that provides symptomatic relief in acute myocardial infarction (MI) by reducing myocardial oxygen demand through venous and arterial dilation. This decrease in preload and afterload decreases the workload on the heart, thereby reducing the demand for oxygen.
**Why the Correct Answer is Right**
Nitroglycerin works by releasing nitric oxide (NO), which activates guanylate cyclase in vascular smooth muscle cells, leading to increased levels of cyclic guanosine monophosphate (cGMP). This results in smooth muscle relaxation, causing vasodilation of both arterioles and venules. The decrease in preload reduces the volume of blood returning to the heart, reducing the workload on the heart and decreasing the demand for oxygen. This is particularly beneficial in acute MI, where the heart is under significant stress.
**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because beta-blockers, while useful in managing hypertension and heart failure, do not provide immediate symptomatic relief in acute MI. They are, however, useful in reducing the risk of arrhythmias and improving long-term outcomes.
**Option B:**
This option is incorrect because calcium channel blockers, while useful in managing hypertension and angina, do not provide the immediate symptomatic relief in acute MI that nitroglycerin does. They can, however, be used in conjunction with nitroglycerin to manage angina.
**Option C:**
This option is incorrect because morphine is used in acute MI to manage pain and anxiety, but it does not reduce myocardial oxygen demand.
**Clinical Pearl / High-Yield Fact**
Nitroglycerin is a vasodilator that reduces myocardial oxygen demand through venous and arterial dilation, providing symptomatic relief in acute MI. It is essential to use it judiciously, as it can cause hypotension, especially in patients with pre-existing hypotension or right ventricular infarction.
**Correct Answer:** C. Morphine.