A patient with inferior wall myocardial infarction is in shock. The reason is: September 2008
**Inferior Wall Myocardial Infarction and Shock**
**Core Concept**
Inferior wall myocardial infarction (IWMI) can lead to shock due to the involvement of the right coronary artery (RCA), which supplies the right ventricle and the inferior wall of the left ventricle. The right ventricle is particularly vulnerable to ischemia due to its thin wall and high oxygen demand.
**Why the Correct Answer is Right**
IWMI can cause shock through several mechanisms. The most common reason is right ventricular infarction (RVI), which can lead to a decrease in cardiac output and peripheral perfusion. This is because the right ventricle is responsible for pumping blood to the lungs, and its failure can cause a decrease in pulmonary blood flow and subsequent hypotension. Additionally, IWMI can also cause a decrease in systemic vascular resistance due to the release of vasodilatory mediators, such as prostaglandins and nitric oxide.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while left ventricular failure can cause shock, it is not the primary reason for shock in IWMI.
**Option B:** This option is incorrect because while cardiac tamponade can cause shock, it is not a direct consequence of IWMI.
**Option C:** This option is incorrect because while cardiogenic shock can cause shock, it is not the primary reason for shock in IWMI.
**Clinical Pearl / High-Yield Fact**
IWMI is a classic example of a condition where the clinical presentation does not always match the electrocardiographic (ECG) findings. A patient with IWMI may have a normal or non-diagnostic ECG, but still have significant right ventricular dysfunction.
**Correct Answer:** A. Right ventricular infarction.