Insights into acute aortic dissection

Abstract

Aortic dissection represents one of the most catastrophic and complex cardiovascular diseases. Its origin is related to an intimal tear with course of blood flow into the aortic wall and division of the aortic lumen into two different lumens, defined as the true and false lumen, separated by a septum or intimal flap. Based on the location of the entry tear, aortic dissections are classified as type A when the proximal tear is located in the ascending aorta and as type B when the tear is present after the origin of the left subclavian artery (Stanford classification). The overall incidence of the acute aortic dissection as a cause of mortality in the population, seems to be around 0.5% per year, with a frequency of about 2.9-4 per 100.000 people/year, about two times higher than aortic aneurysm rupture.

The main objective of this thesis is to look insight acute aortic dissection in the contemporary era, during which new data modify continuously our knowledge and the consequent management of such patients. In particular, our studies focused on the role of the aortic diameter as cause of acute type B aortic dissection (ABAD), on the importance of the preoperative conditions of acute dissected patients in determining the outcome and on the currentusefulness and availability of specific biomarkers for making a rapid serologic diagnosis of acute dissection.

This research project showed some interesting results. The diameter may not be considered as a fundamental parameter to predict acute dissection, highlighting as it may occurs frequently in patients with a normal aortic diameter and not affected by predisposing factors like connective tissue disorders. In acute dissected patients requiring open or/and endovascular approaches, results are strictly associated with pre-operative conditions. In ABAD patients, presence of refractory pain and/or hypertension, in the absence of any hemodynamic and/or ischemic complication, categorizes a group at intermediate risk for in-hospital mortality. Such risk stratification is helpful in predicting the outcome and may assist surgeon in advising patients and their families about the realistic chances of the operation. Follow-up of ABAD patients treated medically in the acute setting evidenced as aortic diameter of less than 4 cm at presentation was associated with increased aortic expansion during follow-up while female gender, intramural hematoma and use of calcium channel blockers predicted decreased aortic expansion. For the assessment of acute and chronic diseases of the aorta, until now routine laboratory tests have played only a minor role and actually no standard blood-based test are yet available for the diagnosis and follow-up of these patients. Although not specific, actually only the D-dimer may be useful as serological diagnosis in the acute setting.

As Charcot stated in the 19th century, ”disease is very old and nothing about it has changed. It is we who change, as we learn to recognize what was formerly imperceptible.” With this thesis we tried to extend insights into acute aortic dissection, providing additional information both for a better management of these patients and to generate innovative research hypothesis