Cavitation Threshold with Respect to Dp/Dt: Evaluation in 29 Mm Bileaflet, Pyrolitic Carbon Heart Valves

Abstract

A total of 15 bileaflet mechanical heart valves were studied in a pulse duplicator at the Helmholtz Institute (Aachen, Germany) under conditions approximating first, a physiological pressure curve and subsequently, a sinusoidal pressure curve. In this study Edwards-Duromedics valves of the modified specification were compared with the earlier version of the Edwards-Duromedics valve as well as with St. Jude Medical valves. Each valve was tested at a series of nine (9) conditions. At each condition, without altering the valve installation or the systemic conditions, each valve was filmed by two separate video systems: the Helmholtz Institute strobe light system and a high speed video recording system. All data, as recorded by each system, was then independently analyzed by both of the two contributing groups and subsequently compared. In this manner, it was possible to objectively verify not only the consistency of the data obtained, but to also determine the relative reliability of the methods for cavitation threshold detection.

Cavitation in Non-Newtonian Fluids

“…In 1976, cavitation was first suggested to be related to erosion of titanium struts of a caged ball mechanical heart valve (Zubarev et al 1976) but it was only in the mid 1980s that cavitation has clinically been found to cause valve failure and valve fragment embolization (Deuvaert et al 1989;Alvarez and Deal 1990). In a later study, Kingsbury et al (1993) reconfirmed the findings reported by Graf et al by visually observing cavitation at dP/dt levels within the physiological range. 6.15 for the case of a rigidly mounted bileaflet valve .…”

Differentiation between gaseous and formed embolic materials in vivo. Application in prosthetic heart valve patients.

“…However, three different types of cavitation bubbles were described in a recent study of prosthetic valve function, one of which is larger and has a longer life span than previously assumed. 28 The exact mechanism of the microemboli generation associated with the valve implant remains to be determined. …”

Mechanical heart valve cavitation

“…In vivo, the mitral position has traditionally been of focus in cavitation studies as it has been assumed to create the harshest valve closing conditions. Later, Kingsbury and colleagues reconfirmed the findings of Graf and colleagues by visually observing cavitation at dP/dt levels within the physiological range [28]. However, a new laboratory technique has recently found that the valve occluder closing velocity, expressed as projected dynamic [101] with permission.…”