What are the odds of surviving an aortic dissection? pretty low?

Depends: Reasonably good if diagnosed early and the patient is otherwise a good surgical candidate. Mortality can vary from 10% to 80% depending on age, time of diagnosis, site of the dissection, presence or absence of other medical conditions such as heart, kidney or lung disease.

Varies: Dissections in the ascending part of the aorta are most fatal and most common , they require urgent surgical repair otherwise has high mortality up to 80% but dissection in other areas like descending aorta has much lower mortality.