@ Hemodynamic factors on progression of Acute Aortic Dissection 1. blood pressure 2. dp/dt 3. flow volume, flow velosity 4. viscosity 5. turbulence

@ Hemodynamic factors on progression of Acute Aortic Dissection 1. blood pressure 2. dp/dt 3. flow volume, flow velosity 4. viscosity 5. turbulence

Non-pulsatile flow Pulsatile flow

1. Anagnostopoulos, C. E., Prabhakar, M. J. S. and Kittle, C. F.: Aortic dissections and dissecting aneurysms. Am. J. Cardiol. 30, 263-273, 1972. 2. Wheat, M. W. Jr., Palmer, R. F. and Bartley, T. D.: Treatment of dissecting aneurysms of the aorta without surgery. J. Thorac. Cardiovasc. Surg. 50, 364-373, 1965. 3. DeBakey, M. E., McCollum, C. H. and Crawford, E. S.: Dissection and disscting aneurysms of the aorta Twenty year follow up of five hundred twentyseven patients treated surgically. Surgery 92, 1118-1134, 1982. 4. ProKopf, E. K., Palmer, R. F. and Wheat, M. W.: Hydrodynamic Forces in dissecting aneurysms in vitro studies in a Tygon model and in dog aortas. Circ. Res. 27, 121-127, 1970. 5. Moran, J. F., Derkac, W. M. and Conkle, D. M.: Pharmacologic control of acute aortic dissection in hyperfensive dogs. Surg. Forum 29, 231-234, 1978. 7. Shennan, T.: Dissecting aneurysms. In Medical Research Council Special Reports Series No. 193. HM stationary office, London 1934. 8. Hirst, A. E., Jhones, V. J. and Kime, S. W.: Dissecting aneurysms of the aorta: A review of 505 cases. Medicine 37, 217-279, 1958. 9. Hirst, A. E. and Gore, I.: Is cystic medionecrosis the caure of dissecting aortic aneurysm? Circulation 53, 915-916, 1976. 10. Schlattmann, T. J. M. and Becker, A. E.: Pathogenesis of dissecting aneurysm of aorta compara tive histopathologic study of significance of medial changes. Am. J. Cardiol. 39, 21-26, 1977. 11. Willens, S. L. Malcolm, J. A. and Vazquez, J. M.: Experimental infarction (medial necrosis) of the Dog's aorta. Am. J. Pathol. 47, 695-711, 1965. 12. Simpson, C. F., Kling, J. M. and Palmer, R. F.: Beta-aminopropionitrile induced dissecting aneur yom of turkey: Treatment with propranorol. Toxic. Appl. Pharmacol. 16, 143-153, 1970. 13. Blanton, F. S., Muller, W. H. and Warren, W. D.: Experimental production of dissecting aneurysms of the aorta. Surgery 45, 81-90, 1959. 14. Carney, W. I., Rheinlander, H. F. and Cleveland, R. J.: Control of acute aortic dissection. Surgery 78, 114-120, 1975. 15. Robertson, J. S. and Smith, K. V.: Analysis of certain factors associated with production of experimental dissection of aortic media in relation to pathogenesis of dissecting aneurysm. J. Pathol. Bacteriol. 60, 43-49, 1948. 16. Hirst, A. E. and Jhons, V. J.: Experimental dissection of Media of aorta by pressure, its relation to spontaneous dissecting aneurysm. Circ. Res. 10, 897-903, 1962. 17. Wolinsky, H. and Glagov, S.: Comparison of abdominal and whoracic aortic medial structure in

mammals: Deviation of man from the usual pattern. Circ. Res. 25, 677-686, 1969. 18. Wheat, M. W. Jr.: Treatment of dissecting aneurysm of the aorta Current status. Prog. Cardiovasc. Dis. 16, 87-101, 1973.

Experimental Study on Progression of Acute Aortic Dissection Kazutoyo SHIRAKAWA 2nd Department of Surgery, Okayama University Medical School 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.