12 Key and Core Catalog With a mechanical key system, the level of security is determined by masterkey control. A masterkey system enables facilities of any size to manage the building by defining access by person and by area in increasing levels of complexity. Since BEST invented the standard for masterkey systems, there is no
When they occur in the upper part of the aorta, they are called thoracic aortic aneurysms. Aneurysms can occur anywhere in the thoracic aorta, including the ascending aorta near the heart, the aortic arch in the curve of the thoracic aorta and the descending aorta in the lower part of the thoracic aorta.
Aortic aneurysm is a pathological dilatation of the normal aortic lumen involving one or several segments . The most used criterion defines aneurysm as a permanent dilatation at least 1,5 times that of expected normal diameter of that given aortic segment , although no definition is universally accepted. Aneurysms are described in terms of location, size, morphological appearance and origin.