Continuous murmur is heard in?
**Core Concept**
Continuous murmur is a type of heart murmur that is heard throughout the cardiac cycle, from the beginning of systole to the end of diastole. This is typically due to a continuous flow of blood through a vascular bed or a cardiac anomaly that results in abnormal blood flow.
**Why the Correct Answer is Right**
Continuous murmur is often associated with patent ductus arteriosus (PDA), a congenital heart defect characterized by the failure of the ductus arteriosus to close after birth. The ductus arteriosus is a normal fetal structure that connects the pulmonary artery to the aortic arch. In PDA, the ductus arteriosus remains patent, allowing blood to flow from the aorta into the pulmonary artery throughout the cardiac cycle. This results in a continuous murmur that can be heard best at the left upper sternal border.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because aortic stenosis is typically associated with a systolic ejection murmur, not a continuous murmur.
**Option B:** This option is incorrect because pulmonary stenosis is typically associated with a systolic ejection murmur, not a continuous murmur.
**Option C:** This option is incorrect because aortic regurgitation is typically associated with a diastolic murmur, not a continuous murmur.
**Clinical Pearl / High-Yield Fact**
The continuous murmur of PDA is often described as a "machinery" murmur due to its distinctive sound, which is similar to the sound of a machine.
**Correct Answer:** A. Patent ductus arteriosus.