X-ray features of ASD are all except
**Core Concept**
Atrial septal defect (ASD) is a congenital heart defect characterized by an abnormal opening in the atrial septum, allowing blood to flow between the left and right atria. The X-ray features of ASD are related to the increased volume load on the right heart chambers.
**Why the Correct Answer is Right**
The X-ray features of ASD include an enlarged cardiac silhouette, particularly the right atrium and right ventricle. The enlarged cardiac silhouette is due to the increased volume load on the right heart chambers, leading to stretching and dilation of the right atrium and right ventricle. The increased volume load is also reflected in the increased pulmonary vascular markings, which are a result of the increased blood flow through the pulmonary arteries.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe an X-ray feature of ASD. The correct feature is an enlarged cardiac silhouette, not a decreased cardiac silhouette.
**Option B:** This option is incorrect because it is not a specific X-ray feature of ASD. While a left axis deviation may be present in some patients with ASD, it is not a characteristic X-ray feature.
**Option C:** This option is incorrect because it is a characteristic X-ray feature of ASD. The increased pulmonary vascular markings are a result of the increased blood flow through the pulmonary arteries.
**Clinical Pearl / High-Yield Fact**
The key X-ray feature of ASD is the enlarged cardiac silhouette, particularly the right atrium and right ventricle. Remember that ASD is characterized by an increased volume load on the right heart chambers, leading to stretching and dilation of the right atrium and right ventricle.
**Correct Answer:** C. Increased pulmonary vascular markings.