Aortic dissection: anatomic types and surgical approaches.

Abstract

Our classification system of acute dissection of the aorta is based on the site of the main intimal tear: Type A: on the ascending aorta; type B: on the transverse aortic arch; type C: on the descending aorta. The extension of the dissecting process is classified as "antegrade" or "retrograde". Acute dissection involving the ascending aorta is an absolute surgical urgency. Any delay in referring the patient to a proper surgical institution or to the operating room increases the risk of death. Fifty per cent of patients, indeed, either untreated or medically supported, die within 48 hours after the onset of symptoms. Surgical therapy is mainly aimed at preventing the patient from dying from intrapericardial rupture of the aorta or from acute massive aortic regurgitation. In type A, it is necessary to replace the ascending aorta with a bloodtight Dacron prosthesis after resecting the entry site, if possible. Downstream, joining the two dissected cylinders by two running sutures and the aid of GRF glue, seals the false lumen. Upstream, the reconstruction of the aortic root and the resuspension of the aortic valve, also by means of running sutures and GRF glue, suppress the aortic valve insufficiency in 90% patients. However, in case of pre-existing annulo-aortic ectasia, the ascending aorta must be replaced by a composite tube according to the Bentail technique. The use of GRF glue since the beginning of 1977, has dramatically improved the immediate and long-term results, accounting for a hospital mortality rate of 10%, in patients less than 65 years old. In type B, resecting the entry site requires that the transverse arch be partially or totally replaced. It is, therefore, mandatory to protect the Central Nervous System. In our experience this is best achieved by perfusing the carotid arteries with cold blood (6 degrees C) during circulatory arrest at moderate core hypothermia (28 degrees C). With this technique of "Cerebroplegia", the hospital mortality rate has been lowered to 28%, higher, though, than in patients undergoing isolated replacement of the ascending aorta. In type C, only the dissections demonstrating symptoms of major complications (rupture or deleterious ischemia) require urgent surgical treatment. In the remaining cases, medical treatment, based on permanent and accurate control of the patient's blood pressure, lead to a good long-term survival rate. Close survey at regular intervals, by means of CT scan or MNR is mandatory to detect any aneurysmal evolution, which may require surgery.(ABSTRACT TRUNCATED AT 400 WORDS)