The following statements are true of patent ductus aeriosus(PDA) except –
**Core Concept**
The patent ductus arteriosus (PDA) is a congenital heart defect characterized by the failure of the ductus arteriosus, a fetal blood vessel, to close after birth. This condition leads to an abnormal connection between the **aorta** and the **pulmonary artery**. The underlying principle being tested involves the physiological changes that occur at birth and the clinical implications of a PDA.
**Why the Correct Answer is Right**
Since the exact options are not provided, let's discuss a general approach to understanding PDA. Normally, the ductus arteriosus closes shortly after birth due to increased oxygenation and a decrease in **prostaglandin** levels. A PDA can lead to excessive blood flow to the lungs, causing **pulmonary hypertension** and potentially heart failure. The correct answer would be based on understanding which statement does not align with the typical presentation, diagnosis, or management of PDA.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific statement, we can't directly address why it's incorrect, but typically, incorrect options might misstate the direction of blood flow, the timing of closure, or the effects on the heart and lungs.
**Option B:** Similarly, without the statement, we can speculate that an incorrect option might confuse the clinical presentation of PDA with another condition or misinterpret the role of prostaglandins.
**Option C:** An incorrect statement might inaccurately describe the anatomical connection or the hemodynamic consequences of a PDA.
**Option D:** This option might be incorrect if it misrepresents the typical treatment approach for PDA, which often involves **indomethacin** for pharmacological closure or surgical ligation.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that a PDA typically presents with a continuous murmur ("machinery" murmur) best heard at the left upper sternal border. This is crucial for diagnosis and distinguishing PDA from other congenital heart defects.
**Correct Answer:** Correct Answer: D. Increased pulmonary vascular resistance is a contraindication for PDA closure.