**Question:** Ascending aorta is involved in following types of dissecting aneurysm except

A. False Lumen Aneurysm
B. True Lumen Aneurysm
C. False Lumen Aneurysm and True Lumen Aneurysm
D. True Lumen Aneurysm and False Lumen Aneurysm

**Correct Answer:** C. False Lumen Aneurysm and True Lumen Aneurysm

**Core Concept:**
A dissecting aneurysm is a type of aortic aneurysm where the inner layer of the aortic wall, called the intima, tears and the blood enters the middle layer (media) causing separation of the layers. This results in two lumens - a true lumen (blood flow in the normal aortic wall) and a false lumen (blood flow in the separated layers).

**Why the Correct Answer is Right:**
Dissecting aneurysms involving the ascending aorta can be categorized into two types based on the involvement of the true and false lumen:
1. True Lumen Aneurysm: A type of dissecting aneurysm where the true lumen remains patent (open) with blood flow in the normal aortic wall. This type is less common and may lead to aortic regurgitation or occlusion of involved artery(s).
2. False Lumen Aneurysm: A type of dissecting aneurysm where the false lumen remains patent, causing blood flow in the separated layers. This type is more common and may lead to occlusion of the involved artery(s) or result in embolization of blood clots formed in the false lumen to various organs and tissues.

**Why Each Wrong Option is Incorrect:**
A. False Lumen Aneurysm and True Lumen Aneurysm: This option combines two distinct types of dissecting aneurysms described above. Ascending aorta dissecting aneurysms are typically classified as either True Lumen Aneurysm or False Lumen Aneurysm, not both.

B. True Lumen Aneurysm and False Lumen Aneurysm: This option also combines two types of dissecting aneurysms. Dissecting aneurysms are classified as either True Lumen Aneurysm or False Lumen Aneurysm, not both.

C. False Lumen Aneurysm and True Lumen Aneurysm: This option also combines two types of dissections. Dissecting aneurysms are classified as either True Lumen Aneurysm or False Lumen Aneurysm, not both.

D. True Lumen Aneurysm and False Lumen Aneurysm: This option also combines two types of dissections. Dissecting aneurysms are classified as either True Lumen Aneurysm or False Lumen Aneurysm