The Starr-Edwards Aortic Ball Valve: Flow Characteristics, Thrombus Formation and Tissue Overgrowth
The Starr-Edwards ball valve has been one of the more commonly used aortic valve prostheses. In the study reported here, in vitro velocity, shear-stress and pressure drop measurements were made under steady-flow conditions and used to interpret some of the failure modes of this prosthesis as observed at autopsy. The findings show that some failure modes can be explained by the nature of the values for velocities and shears in the near vicinity of the valve.
Our results indicate that the Starr-Edwards ball valve has major fluid dynamic drawbacks such as: (a) relatively large pressure drop (17.3 to 31.0 mm Hg at a flow rate of 417 cm3 /sec), (b) hydrodynamically unstable poppet, (c) regions of flow separation at the base of each of the three struts, (d) region of flow stagnation at the apex of the cage (~7 to 15 mm in diameter) (e) large wall-shear stresses (~500–2000 dynes/cm2) and bulk turbulent shear stresses (on the order of 100–5000 dynes/cm2) in the immediate downstream vicinity of the valve, and (f) large shear stresses adjacent to the poppet surface and struts (on the order of 102–103 dynes/cm2).
The observed stagnation zone could encourage thrombus formation on the apex of the cage, while the observed regions of flow separation could lead to thrombus formation and tissue overgrowth at the base and upwards along the struts. The observed wall shear could lead to damage of endothelial tissue in the proximal ascending aorta, to hemolysis, and to thrombus formation. In addition, the elevated shears adjacent to the struts and the surface of the poppet could lead to increased hemolysis with those Starr-Edwards ball valves having cloth covered struts.
Examinations have been made at the USC-LA County Medical Center of 13 Starr-Edwards aortic ball valves recovered during autopsy. Thrombus formation and tissue overgrowth were observed at various locations on the recovered valves. The locations of thrombus formation and tissue overgrowth correlate well with those predicted by the in vitro fluid dynamic data. In addition, endothelial damage and tissue proliferation in the proximal ascending aorta were observed in some cases. Similar pathologic findings have also been observed by other investigators.
KeywordsWall Shear Stress Thrombus Formation Prosthetic Heart Valve Stagnation Zone Ball Valve
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- Blackshear, P.L. (1972a) Hemolysis at prosthetic surfaces. Chemistry of Biosurfaces (Edited by Hair, M.L.) Vol. 2. pp. 523–561. Marcel Dekker, New York.Google Scholar
- Blackshear, P.L. (1972b) Mechanical hemolysis in flowing blood. Biomechanics - Its Foundations and Objectives (Edited by Fung, Y.C.,Perrone, N. and Anliker, M), pp. 501528. Prentice - Hall, Englewood Cliffs.Google Scholar
- Crawford, F.A., Sethi, G.K. Scott, S.M., and Takaro, T. (1973) Systemic emboli due to cloth wear in a Starr-Edwards model 2320 aortic prosthesis. Ann Thorac. Surg 16, 614–619.Google Scholar
- Davey, T.B., Kaufaman, B., and Smeloff, E.A (1966) Pulsatile flow studies of prosthetic heart valves. J. Thorac, Cardiovasc. Surg. 51, 264–267.Google Scholar
- Davila, J.C., Palmer, T.E., Sethi, R.S., DeLaurentis, D.A., Enriquez, F., Rincorn,N., and Lautsch, E.V. (1966) The problem of thrombosis in artificial cardiac valves. Heart Substitutes: Mechanical and Transplant(Edited by Brest, A.N.), pp. 25–36. Charles C. Thomas, Springfield.Google Scholar
- Eyster, E., Rothchild, J., and Mychajliw, 0. (1971) Chronic intravascular hemolysis after aortic valve replacement. Circulation XLIV 657–665.Google Scholar
- Figliola, R.S. (1976). A study of the hemolytic potential of prosthetic heart valve flows based on local in vitro stress measurements. M.S. thesis, University of Notre Dame.Google Scholar
- Figliola, R.S. (1979) In Vitro Velocity and Shear Stress Measurements in the Vicintiy of Prosthetic Heart Valves Using Laser Doppler and Hot-Film Anemometry. Ph.D. thesis, University of Notre Dame.Google Scholar
- Fry, D.L. (1968) Acute vascular endothelial changes associated with increased blood velocity gradients. Circ. Res. 22, 165–197.Google Scholar
- Fry, D.L. (1969) Certain histological and chemical responses of the vascular interface to acutely induced mechanical stress in the aorta of the dog. Circ. Res. 24, 93–108.Google Scholar
- Hamby, R.I., Lee, R.L., Aintablian, A., Wisoff, B.G., and Hartstein, M.L. (1974) Cinefluorographic study of the aortic ball-cage prosthetic valve. Am.J. Cardiol. 34, 276–283.Google Scholar
- Hellums, J.D., and Brown III, C.H. (1977) Blood cell damage by mechanical forces. Cardiovascular Fluid Dynamics (Edited by Hwang, N.H.C. and Normann, N.A.),pp. 799–823. University Park Press, Baltimore.Google Scholar
- Hung, T.C., Hochmuth, R.M., Joist, J.H., and Sutera, S.P. (1976) Shear-induced aggregation and lysis of platelets. Trans. Am. Soc. Artis. Intern. Organs 22, 285–290.Google Scholar
- Lefemine, A.A., Miller, M„ and Pinder, G,C, (1974) J, Thorac, Cardiovasc. Surg. 67, 857–862.Google Scholar
- Mohandas, N., Hochmuth, R.M., and Spaeth, E.E. (1974) Adhesion of red cells to foreign surfaces in the presence of flow. J. Biomech. Mat. Res. 8, 119–136.Google Scholar
- Nevaril, C.G., Hellums, J.D., Alfey Jr., C.P. and Lynch, E.C. (1969) Physical effects in red blood cell trauma. A. I. ChE. J. 15, 707–711.Google Scholar
- Ramstack, J.M. Zuckerman, L., and Mockros, L.F. (1979) Shear induced activation of platelets. J. Biomech. 12, 113–125 (1979).Google Scholar
- Roberts, W.C., and Morrow, A.G. (1979) Anatomic studies of hearts containing caged-ball prosthetic valves. Johns Hopkins Med. J. 121, 271–295.Google Scholar
- Roberts, W.C., and Morrow, A.G. (1967b) Late post-operative pathological findings after cardiac valve replacement. Circ, Suppl. (1) 35-36, 48–62.Google Scholar
- Roberts, W.C. (1976) Choosing a substitute cardiac valve: type, size, surgeon. Am. J. Cardiol. 38, 633–644.Google Scholar
- Santinga, J.T., and Kirsh, M.M. (1972) Hemolytic anemia in series 2300 and 2310 Starr-Edwards prosthetic valves. Ann Thorac. Surg. 14, 539–544.Google Scholar
- Smeloff, E.A., Huntley, A.C., Davey, T.B., Kaufman, B., and Gerbode, F. (1966) Camparative study of prosthetic heart valves. J. Thorac. Cardiovasc. Surg. 52, 841–846.Google Scholar
- Smithwick III, W., Kouchoukos, N.T., Karp, R.B., Pacifico,:D., and Kirklin, J.W. (1975) Late stenosis of Starr-Edwards cloth-covered prostheses. 20, 249–255.Google Scholar
- Stein, D.W., Rahimtoola, S.H., Kloster, F.E., Selden, R., and Starr, A. (1976). J. Thorac. Cardiovasc. Surg. 71, 680–684.Google Scholar
- Weiting, D.W. (1969) Dynamic Flow Characteristics of Heart Valves. Ph.D. thesis, University of Texas, Austin.Google Scholar
- Yoganathan, A.P. (1978) Cardiovascular Fluid Mechanics. Ph.D. thesis, California Institute of Technology, Passadena.Google Scholar
- Yoganathan, A.P. Reamer, H.H. Corcoran, W.H., and Harrison, E.C. (1979a) A laser-Doppler anemometer to study velocity fields in the vicinity of prosthetic heart valves. Med. Biol. Engng. Computing 17, 38–44.Google Scholar