There are many factors pointed out theoretically as influencing the progression of acute aortic dissection, but few factors have been proved experimentally. In this study, hemodynamic factors were evaluated experimentally as to how they related to the progression of aortic dissection. DeBaKey type IIIb aortic dissections were made by Blanton's method in the descending thoracic aorta of dogs. At the initiation of progression of aortic dissection, blood pressure, LV dp/dt, aorta dp/dt, flow volume, flow velocity and blood viscosity were measured. Each factor was also evaluated by Prokopf's method in which aorta was inserted in the closed circuit with pump.
As to hemodynamic factors affecting the progression of acute aortic dissections; 1) Hypertension was the most important factor. 2) LV dp/dt was not so important, as mentioned by Wheat. 3) The flow volume, velocity and viscosity were thought to be important theoretically, but these factors did not prove to be significant in this study. Retrograde dissections progressed after making the intimal tear wider and longer, and by increasing peripheral resistances. The dissected layers in the media were variable, but most of the specimens were dissected at the outer layer in the proximal area and at the inner layer in the distal area.