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Acute Aortic Disease.. - Index of

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Classification <strong>of</strong> <strong>Aortic</strong> Dissection 19<br />

Figure 11 Graphical display <strong>of</strong> International Registry <strong>of</strong> <strong>Acute</strong> <strong>Aortic</strong> Dissection-code<br />

<strong>of</strong> entry site locations in relation to 30-day-mortality. The more proximal the entry site<br />

location the higher the in-hospital mortality in percent.<br />

imaging technology, differentiates type A dissections, based on location <strong>of</strong> the<br />

most proximal entry site, into subgroups with distinct prognoses. Moreover,<br />

by defining dissection according to proximity to the aortic valve, we found a<br />

declining death rate with increasing distance between entry site and aortic valve.<br />

Not surprisingly, IRAD had previously identified shock and tamponade as significant<br />

predictors <strong>of</strong> death (40,74,75,78,79), supporting the concept <strong>of</strong> a correlation<br />

<strong>of</strong> entry site and prognosis (Fig. 11).<br />

Through incorporation <strong>of</strong> diagnostic imaging information from modern<br />

technology, the IRAD classification system ideally connects anatomic detail with<br />

prognostic information. The knowledge <strong>of</strong> entry location, thus, may help to<br />

estimate the individual risk in proximal dissection better than either the Stanford<br />

or DeBakey classification. Prognosis in proximal dissection is diverse considering<br />

differences <strong>of</strong> 30-day-mortality related to entry location. Patients may be classified<br />

according to the IRAD-code as A1, A2, and A3. Type B dissection is prognostically<br />

the same, regardless <strong>of</strong> entry site, and the IRAD subclassification, B1 to B3,<br />

is useful only from a descriptive perspective.<br />

Various mechanisms may explain the inverse relationship between the<br />

anatomic proximity <strong>of</strong> the entry site and the outcome in patients with acute<br />

dissection. First, the more proximal the origin <strong>of</strong> the dissected aortic layer, the<br />

more likely is a mechanical obstruction <strong>of</strong> coronary ostia, rupture within the<br />

pericardial sac (79), and/or new aortic regurgitation. Second, loss <strong>of</strong> elasticity in<br />

proximal aortic segments may predispose to aortic wall disintegrity preferentially<br />

adjacent to the sinuses <strong>of</strong> valsalva (80). Third, cyclic changes <strong>of</strong> aortic radius and<br />

distensibility (pressure strain elastic modulus) are most compromised at the level

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