**Question:** A patient with M of 4 yrs duration presents with dizziness and HR 52/min, probable cause is:

A) Hypoglycemia
B) Inferior wall MI
C) Sick-sinus syndrome
D) Autonomic dysfunction

**Core Concept:**
The question is asking about the probable cause of a patient with a history of 4 years of symptoms like dizziness and an abnormally low heart rate (52 beats per minute) after excluding other causes like hypoglycemia (low blood sugar). We need to consider the remaining options: Inferior wall MI, Sick-sinus syndrome, and Autonomic dysfunction.

**Why the Correct Answer is Right:**

D) **Autonomic Dysfunction:** This condition involves abnormalities in the autonomic nervous system, which controls involuntary functions like heart rate, blood pressure, and digestion. In this context, hypotension (low blood pressure) and bradycardia (low heart rate) are common symptoms of autonomic dysfunction. Therefore, the probable cause in this case is Autonomic Dysfunction.

**Why Each Wrong Option is Incorrect:**

A) **Hypoglycemia:** Hypoglycemia is characterized by low blood sugar levels, which typically causes symptoms like confusion, sweating, and tremors, not dizziness and bradycardia. Hypoglycemia is less likely as the patient's symptoms are not consistent with this condition.

B) **Inferior wall MI (Myocardial Infarction):** MI is caused by a blockage in a coronary artery, leading to a decrease in blood supply to the heart muscle. The presenting symptoms are typically chest pain, angina, and tachycardia (fast heart rate), not dizziness and bradycardia.

C) **Sick-Sinus Syndrome:** This is a specific condition characterized by an abnormally slow heart rate (bradycardia) due to a dysfunction in the sinus node, which is responsible for regulating heart rate. In this case, the patient's symptoms are not consistent with Sick-Sinus Syndrome, making it less likely as the probable cause.

In conclusion, based on the provided information, the correct answer is Autonomic Dysfunction as it presents with symptoms like dizziness and bradycardia. Hypoglycemia, inferior wall MI, and Sick-Sinus Syndrome are less likely causes due to the inconsistency in presenting symptoms.