True about third hea sound (H3)-
**Core Concept**
A third heart sound (S3) is a low-frequency diastolic heart sound that occurs shortly after the second heart sound (S2) during late diastole. It is associated with rapid filling of the ventricle and is often heard in conditions where there is increased volume or pressure overload on the ventricle.
**Why the Correct Answer is Right**
The third heart sound is generated by the rapid filling of the ventricle, which causes the ventricular walls to bulge outward and create a sound. This sound is often heard in conditions such as heart failure, where there is increased volume overload on the ventricle, or in conditions such as hypertrophic cardiomyopathy, where there is increased pressure overload on the ventricle. The S3 sound is typically heard best at the apex of the heart.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the third heart sound is not a sign of increased ventricular contractility. Instead, it is a sign of increased ventricular filling.
* **Option B:** This option is incorrect because the third heart sound is not a sign of aortic stenosis. Aortic stenosis is typically associated with a systolic ejection murmur.
* **Option C:** This option is incorrect because the third heart sound is not a sign of a normal heart. While it is a normal finding in infants and children, in adults it is often a sign of underlying cardiac disease.
**Clinical Pearl / High-Yield Fact**
The third heart sound is often described as a "gallop rhythm" because it sounds like a horse's gallop. This is a classic exam question trap, as the term "gallop" is often associated with a different type of heart sound.
**Correct Answer: C. This option is incorrect because the third heart sound is not a sign of a normal heart. While it is a normal finding in infants and children, in adults it is often a sign of underlying cardiac disease.**