This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Classification of aoic dissection depends upon? 
Select and explain. 
A. Cause of dissection, B. Level of aoa affected, C. Percentage of aoa affected, D. None
B: Level of aoa affected
Answer: B: Level of aoa affected 
Explanation: Ans. is 'b' i.e., Level of aoa affectedClassification of Aoic dissectiono The risk and nature of serious complications of dissection depend strongly on the level of aoa affected, with the most serious complications occuring from the aoic valve to the arch.o Thus aoic dissections are generally classified into two types -1. Proximal lesion (Type A)o More common and more dangerous.o Involve either the ascending poion only or both ascending and the descending poion of aoa.2. Distal lesion (Type B)o Involve only discending pa distal to subclan aery.