Aortic dimensions and the risk of dissection
he aorta represents a complex organ system which begins in the aortic ring adjacent to the aortic root with the origin of the two major coronary arteries, and ends at the iliac bifurcation. The subdivision into seven segments seems to be clinically important-the aortic root, the ascending aorta, the ascending aortic arch, the vessel bearing arch, the aortic isthmus, and the thoracic descending and abdominal aorta. The aorta as an organ can be regarded as a biological ''windkessel'', storing kinetic energy during systole which is delivered during diastole in order to maintain a relative constant mean aortic pressure. In particular, a high diastolic blood pressure is important for the coronary perfusion.