Acute Aortic Disease.. - Index of

126 Elefteriades and Koullias
Figure 1 (See color insert) The technique of epi-aortic echocardiography. Note the fluidfilled
interface between the probe and the aortic wall.
1. The diameter of the aorta, in systole and diastole.
2. The thickness of the aortic wall, in systole and diastole. (The aortic
wall thins in systole, under the increased stretch of the higher pressure.
This measurement of subtle differences in a small dimension has a
significant learning curve attached to it.)
3. The blood pressure, in systole and diastole. (In our experiments, the
blood pressure was determined very accurately using intraoperative
direct arterial line monitoring.)
What we found was that the distensibility of the aorta essentially vanishes
as the dimension of the aorta increased (Fig. 3). The normally distensible aorta
became essentially a rigid tube at about 6 cm in diameter.
Likewise, wall stress shows dramatic and serious aberrations as the aorta
grows, again reaching critical levels by about 6 cm aortic diameter (Fig. 4). The
maximal strength of the aortic wall is known by prior investigations done directly
Mechanical Properties of the Aneurysmal
Human Ascending Aorta
d
BP
t
All mechanical characteristics
can be calculated on the basis of
six parameters:
d
t
BP
systole
diastole
Figure 2 The parameters that need to be measured for calculation of mechanical properties
of the aorta.