Aortic aneurism is a severe dilation of the aorta frequently located in its ascending part. It generally appears due to connective tissue degeneration or diseases like in Marfan syndrome, for example. If the ascending aorta aneurism diameter is equal or larger than 5,5 cm, it has to be operated. Otherwise, we risk the fatal aneurism rupture. In the case of leaflet aortic valve insufficiency or other concomitant heart surgery, aortic aneurism should be operated even if the diameter is bigger or even less than 5 cm. Since the risk of the aneurism rupture increases with its width, big ones have to operate upon diagnosis to prevent catastrophic rupture.
Aortic dissection is a medical emergency. It happens when blood enters between the aortic layers through a rupture of the inner one. Blood flow after that dissects the layers throughout the aorta. Dissection could appear on the existing aneurism but also a healthy aorta. If not operated immediately, the fatal aortic rupture will happen in 75% of patients within 48 years. Aortic dissection severely damages organ perfusion, resulting in ischemia of heart, brain, intestines, kidneys, or other organs, depending on the dissection’s severity and extent.
SURGERY OF THE THORACIC AORTA
Both the aneurism and the aortic dissection have to be operated. The affected aorta is resected and replaced by a Dacron graft. That is a tubular graft made of synthetic fabric that is going to be covered form inside by a tiny tissue layer after that. If affected, the aortic valve has to be operated as well. It could be replaced by a composite graft, or repaired along with the aorta. A composite graft is a valve prosthesis attached to a Dacron graft. If the valve repair is feasible, the so-called Thyrone-Davide procedure is the treatment of choice. Dacron graft does not need anticoagulation therapy.
Depending on the diameter, aneurysms should be operated, generally, as soon as possible. Aortic dissection, on the other side, is a medical emergency due to imminent rupture and has to be treated immediately. Elective surgery is scheduled in case of subacute or chronic aneurism, should be scheduled within a few days upon the diagnosis. Isolated aneurism or descending aorta dissections are generally not operated and treated with stent-grafts as a Cath lab procedure.
The Bentall procedure is the replacement of the aortic valve and the ascending aorta with a composite graft along with coronary artery re/implantation. The composite graft is a prosthesis made of an artificial valve attached to a Dacron graft.
To replace the ascending aorta or the aortic arch in particular, it is necessary to stop the heart-lung machine for some time completely. Brain and other organs are preserved by profound hypothermia, so-called the Deep Hypodermic Circulatory Arrest. The additional brain protection is performed by isolated head perfusion.