Aortic Dissection Stanford A

A 58-year-old man with poorly controlled hypertension and bicuspid aortic valve presents with sudden-onset, severe tearing chest pain radiating to the interscapular region. On examination, he is diaphoretic with BP 196/104 mmHg in the right arm and 158/82 mmHg in the left arm, and a pulse deficit in the left radial pulse. An early diastolic murmur is heard at the left sternal border. Urgent CT angiography of the chest with ECG-gating demonstrates a double-lumen appearance of the ascending aorta. The structure marked **C** in the diagram is the most specific imaging finding that confirms the diagnosis of aortic dissection. Which of the following best describes the pathophysiological significance of this structure in Stanford Type A dissection?