Blood velocity and endocarditis.

DESPITE the successful use of anitibioties in the treatment of infective endocarditis, the failure of therapy in perhaps onre third of the patients with this condition keeps it in the forefront as a major threat in heart disease.1 2 The increasing incidence of endocarditis following cardiac surgery has also provided an unexpected and disturbing feature of progress in cardiac management.3In addition to the practical problems of management of this disease a number of per plexing clinical and laboratory questions re main. Thus, the argument as to whether the locus of the infection requires previous trauma, inflammation, vascularization,6 or deformity7 remains undecided. The mechanisms in the progression of verrucae and uleerationis, the formationi of thrombi, the validity of spontaneous cures, and the tendency to recurrence, demand re-evaluationi. It is curious that extremnely large quantities of antibiotics are required to halt the growth of inifective agents at the valve, while a thousandth of these concentrations (calculated for extracellular body water) miay destroy the same organisms in other sites in the body or in vitro.Y2 The antibody titers for some of the antigens of the infecting organism mav have little or no inhibitory effect on the mnicrobial growth at the infected valve or artery.'3-15There can be little doubt that the circulation is seeded continually by organisms that are swept as emboli from a nidus to all the tissues of the body, with the production of local vascular occlusions; vet these pathogenic showers seldom produce local infections or abscesses. If some of these prob-