**Core Concept**
Pectus excavatum is a congenital deformity of the anterior chest wall characterized by a sunken or caved-in appearance, resulting from a defective formation of the sternum and adjacent ribs. This deformity can lead to various respiratory and cardiac complications due to the altered chest cavity and internal organ positioning.

**Why the Correct Answer is Right**
The heart is typically shifted towards the left side in patients with pectus excavatum due to the depressed sternum. This shift is caused by the abnormal growth of the sternum and adjacent ribs, which can lead to a displacement of the heart and mediastinal structures towards the left side. The left-sided heart shift is a classic radiological finding in pectus excavatum patients.

**Why Each Wrong Option is Incorrect**
**Option A:** The heart is shifted towards the left side, not the right side, in pectus excavatum. This option is incorrect because the deformity typically causes the heart to be displaced towards the left, not the right.
**Option B:** Features of pectus excavatum, such as the depressed sternum and abnormal rib growth, may indeed suggest a right middle lobe (RML) consolidation on radiographs. However, this option is not a direct consequence of pectus excavatum, and RML consolidation is not a characteristic feature of this deformity.
**Option C:** The anterior ribs in pectus excavatum are indeed more vertically oriented, giving them a characteristic "7-shaped" appearance. This is a classic radiological finding in pectus excavatum, making this option correct.

**Clinical Pearl / High-Yield Fact**
It's essential to recognize the characteristic radiological features of pectus excavatum, including the depressed sternum, abnormal rib growth, and left-sided heart shift. These findings can help differentiate pectus excavatum from other chest wall deformities and guide further management.

**✓ Correct Answer: D. Heart shifted towards right side.**