Aortic Anatomy and Common Conditions
The Aorta
The aorta is the largest artery in your body. The heart pumps blood out of the left ventricle, through the aortic valve, and into the aorta. The aorta then travels up and around the aortic arch, down the back, and into the abdomen, allowing fresh, oxygenated blood to flow to the entire body.
The aorta is comprised of three layers: intima, media and adventitia.
Aortic Aneurysm
An aortic aneurysm is an abnormal enlargement of the aorta. As the aorta enlarges, the risk for rupture, dissection, and death increases.
Aortic Dissection
A dissection is a tear in the intima of the aorta causing a false lumen in the aorta.An ascending aortic dissection develops in the aorta closest to the heart. Dissection of the ascending aorta can cause stroke, heart attack, heart failure, and cardiac tamponade. The rate of death for an ascending aortic dissection is approximately 1-2% per hour for the first 48 hours.Approximately 25% of patients die after surgery for a Type A aortic dissection, and only about one-half return to activities of daily living within one year.
Descending Aortic Dissection
A descending aortic dissection is a tear in the descending aorta, that travels down the aorta and may extend the entire length of the aorta. Approximately 10% of descending aortic dissections will require an interventional procedure during their initial hospitalization.
When to operate?
The question of when to operate is based upon risk versus benefit. Aneurysm size with the risk of rupture, dissection, and death is balanced with the risk of elective surgery. The risk of elective ascending aorta replacement is generally less than 5%.
Dissections do occur at small sizes.Aortic dissections occur at an average size of 53mm. Half of the dissections occur above that size, and half below. Aortic diameter >or = 5.5 cm is not a good predictor of type A aortic dissection: observations from the International Registry of Acute Aortic Dissection (IRAD). Pape et al. Journal of American College of Cardiology. 2010, 55(9) 841-857.
2022 AHA/ACC Guidelines
At centers with Multidisciplinary Aortic Teams and experienced surgeons, the threshold for surgical intervention for sporadic aortic root and ascending aortic aneurysms has been lowered from 5.5 to 5.0 cm in selected patients, and even lower in specific scenarios among patients with heritable thoracic aortic aneurysms.