Aortic Dissection

Excerpt

Aortic dissection, though uncommon, is a catastrophic vascular disorder characterized by a tear in the intimal layer of the aorta, leading to the separation of the aortic wall layers. Blood enters between the intima and media, propagating the dissection either proximally or retrograde, resulting in compromised blood flow to vital organs. Acute aortic dissection carries extremely high mortality rates, with many patients dying before reaching emergency care. Patients with chronic aortic dissection, defined as a dissection present for more than 2 weeks, have a slightly better prognosis.

While the classic presentation of acute aortic dissection involves sudden, severe, “tearing” chest pain, subtle presentations often lead to missed diagnoses. Despite the literature, many aortic dissections are missed in the emergency department; only 15% to 43% of verified cases are accurately diagnosed at first presentation. Without treatment, mortality approaches 50% within 48 hours of symptom onset. Despite its rarity, acute aortic dissection requires prompt diagnosis and multidisciplinary healthcare intervention, with better outcomes observed in high-volume centers utilizing experienced teams, “aorta code” protocols, and specialized aortic centers. Further, implementing a multidisciplinary strategy with vascular surgery and cardiology expertise is essential to improving patient outcomes in these life-threatening cases. Aortic dissections are classified anatomically by 2 systems: the Stanford and DeBakey classification systems.

The Stanford system categorizes dissections into 2 types based on whether the ascending or descending part of the aorta is involved (see Image. Stanford Classification of Aortic Dissection).

1. Stanford Type A: This involves the ascending aorta, regardless of the site of the primary intimal tear (see Image. Type A Aortic Dissection), and is defined as a dissection proximal to the brachiocephalic artery.

2. Stanford Type B: This originates distal to the left subclavian artery and involves only the descending aorta; the Society for Vascular Surgery and the Society of Thoracic Surgeons define Stanford type B dissections as those where the entry tear occurs beyond the origin of the innominate artery.

The DeBakey system further subdivides dissections into 3 types based on the origin and extent of the dissection:

1. DeBakey Type 1: Originates in the ascending aorta, aortic arch, and descending aorta

2. DeBakey Type 2: Originates in and is limited to the ascending aorta

3. DeBakey Type 3: Begins in the descending aorta and extends distally above the diaphragm (type 3a) or below the diaphragm (type 3b)

Ascending dissections (Stanford type A or DeBakey types 1 and 2) are nearly twice as common as descending dissections (Stanford type B or DeBakey type 3), necessitating an urgent, specialized approach to reduce the risk of fatal complications such as aortic rupture, stroke, or myocardial infarction (see Image. Aortic Dissection, Type A).