From the Guidelines
The primary distinction between an aortic pseudoaneurysm and a Stanford Type B aortic dissection is that the former involves a dilation of the aorta due to disruption of all wall layers contained by periaortic connective tissue, whereas the latter is characterized by a tear in the inner layer of the aorta that begins in the descending aorta, creating a false lumen. The aortic pseudoaneurysm, as described in the 2014 ESC guidelines 1, is a false aneurysm where blood flow is contained outside the aortic wall by surrounding tissues, often resulting from trauma, infection, or iatrogenic causes. In contrast, a Stanford Type B aortic dissection, as outlined in the 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines 1, involves a tear in the inner layer of the aorta that begins in the descending aorta, distal to the left subclavian artery, creating a false lumen. Key differences include:
- Location: Aortic pseudoaneurysms can occur anywhere along the aorta, while Stanford Type B dissections are limited to the descending aorta.
- Structure: Pseudoaneurysms involve disruption of all wall layers, whereas dissections involve a tear in the inner layer of the aorta.
- Causes: Pseudoaneurysms are often caused by trauma, infection, or iatrogenic factors, while dissections are typically caused by hypertension or aortic disease.
- Treatment: The treatment approaches for these two conditions can vary significantly, with pseudoaneurysms often requiring interventional or open surgical interventions, and dissections typically managed medically unless complications arise. Understanding these differences is crucial for proper diagnosis and management, as highlighted in the guidelines 1.
From the Research
Definition and Pathophysiology
- An aortic pseudoaneurysm is a cavity with a single blood entry port communicating with the aortic lumen, and a pseudocapsule, often caused by a chronic degenerative pathology of the intima and medial layers of the aorta 2.
- A Stanford Type B Aortic Dissection (aortic dissection type B) is a condition where there is a tear in the inner layer of the aorta, causing blood to flow between the layers of the aorta, leading to the formation of a false lumen 3, 4.
Key Differences
- The main difference between an aortic pseudoaneurysm and a Stanford Type B Aortic Dissection is the presence of a single blood entry port and a pseudocapsule in the pseudoaneurysm, whereas in a Type B dissection, there is a tear in the inner layer of the aorta and the formation of a false lumen 2, 3.
- The pathophysiology of the two conditions also differs, with pseudoaneurysms often being caused by chronic degenerative pathology, and Type B dissections being caused by a tear in the inner layer of the aorta 2, 3.
Clinical Implications
- The management of aortic pseudoaneurysms and Stanford Type B Aortic Dissections differs, with endovascular stent grafting being a viable option for both conditions, but with different indications and outcomes 3, 4.
- The need for intervention, such as surgery or thoracic endovascular aortic repair (TEVAR), is higher in primary Type B aortic dissections than in remaining Type B dissections after Type A repair 5.
- A patent primary entry tear is an independent predictor for intervention in patients after surgery for acute Type A aortic dissection, but not in patients with primary Type B aortic dissection 5.