Stanford Type A Aortic Dissection
Aortic dissection occurs when the inner layer (intima) of the aorta tears and blood passes through this separation in the aortic wall. This produces a false channel (lumen) which spirals throughout the length of the aorta. In the United States the prevalence of aortic dissection ranges from 0.2 to 0.8 per 100,000 per year resulting in roughly 2000 new cases per year. Aortic dissection usually causes a severe sharp, tearing pain in the chest and upper back. The involvement of the ascending aorta is referred to as a Stanford Type A aortic dissection. This acute weakening of the aortic wall can lead to aortic rupture.
The presence of the false channel can result in regurgitation of the aortic valve, myocardial infarction (heart attack), stroke, and lack of blood supply to the intestines and ultimately death. The patient’s mortality increases 1 percent per hour after the onset of symptoms. Most patients that develop a Type A aortic dissection have a history of elevated blood pressure, an ascending aortic aneurysm, connective tissue disorder, bicuspid aortic valve, or have endured a stressful/emotional life event. The diagnosis is most commonly made based on history and symptoms however echocardiogram and/or CT scan are commonly used. In A chronic Type A aortic dissection is rare because most patients are treated emergently with surgery. However, chronic ascending aortic dissection is treated based on the diameter, symptoms, and severity of aortic valve insufficiency. In general, they are treated like atherosclerotic and degenerative aortic aneurysms.
Type A (Acute) Type A (Chronic)
Stanford Type B Aortic Dissections
A Stanford Type B aortic dissection involves the aorta beyond the take-off of the left subclavian artery (as seen in the illustration). The intimal tear is usually found beyond the subclavian artery however it can be located in the aortic arch. The false channel propagates distally into the descending and abdominal aorta. The passage of blood through the aortic wall can lead to complications, such as weakening of the lower extremities or paralysis, and lack of blood supply to the intestines or lower extremities. The flow of blood in the false channel can cause these complications by pinching off flow of blood into the branches off the aorta.
Overall, greater than 60-80% of patients with type B aortic dissection have an elevated blood pressure at presentation. Another predominant feature in patients with aortic dissections is the history of cigarette smoking. Approximately 30-40% of patients have a history of atherosclerosis. Ten to twenty percent of patients have history of a connective tissue disorders, prior cardiac or aortic surgery or aortic aneurysm. Approximately 85% of patients can be treated conservatively with blood pressure and heart rate control. Patients require long-term follow-up to evaluate the rate of growth and size of the aorta. Aneurysms can develop in the area which has the dissection. Surgical or endovascular therapies are indicated in acute aortic dissection patients who develop complications such as rupture, persistent pain, lack of blood supply to one or several organ systems, or rapid growth in the aorta. Chronic Type B aortic dissections are followed carefully to detect aortic aneurysm formation and avoid complications.
Type B (Acute) Type B (Chronic)
Aortic Aneurysm Program