INTRAVEGETATION ANTIMICROBIAL DISTRIBUTION IN ENDOCARDITIS - A NUMERICAL-MODEL AND ESTABLISHMENT OF THE CONDITIONS FOR AN IN-VITRO TEST

Two problems appear when it is desired to get good knowledge concernin g transfer of matter through a material, and especially the penetratio n of antibiotics into vegetations on heart valves. One is to build a n umerical model to describe and simulate the process and thus to gain a fuller insight into the nature of the transfer. The other is to devel op an in vitro test to represent the in vivo process, with simple oper ational conditions and accurate measurements. The in vitro test must e nable one to measure the parameters of interest, i.e. the diffusivity of antibiotic through the vegetation, or rather through the blood loca ted in the vegetation. Experiments and calculations are made in order to build a numerical model describing the process and to develop an in vitro test capable of determining the diffusivity. A simulation is ma de with a polymer bead made of Ethylene vinyl acetate saturated by a l iquid such as n-heptane with a slight amount of benzene, The release o f benzene from the polymer bead into n-heptane free from benzene is th e best way for measuring the diffusivity of the benzene (simulating th e antibiotic) through the liquid located in the polymer.