<prompt> Classification of aoic dissection depends upon?Cause of dissectionLevel of aoa affectedPercentage of aoa affectedNone  <response>: 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 Ao 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 Bo Involve only discending pa distal to subclan aery. 