What defines a Stanford type B dissection?

A Stanford type B dissection is characterized by the dissection involving the descending aorta, which is typically defined as the section of the aorta distal to the left subclavian artery. This means that it specifically refers to dissection occurring beyond the branching points for the major arteries, focusing primarily on the thoracic aorta that follows the arch.

The correct choice highlights that this type of dissection entails involvement of the distal portion of the aorta, which is fundamentally what distinguishes it from type A dissections, where the involvement includes or is limited to the ascending aorta and often extends to the arch. Therefore, option C accurately reflects the anatomical definition and clinical distinction pertinent to a Stanford type B dissection. This classification is essential as it influences management and surgical intervention strategies, which significantly differ between type A and type B dissections. Understanding these distinctions is critical in clinical practice for effective patient care in cases of aortic dissection.