RELATIVE BRADYCARDIA IN INFECTIOUS-DISEASES

Relative bradycardia in infectious diseases is a poorly defined term. No exact and useful definition exists and the underlying mechanisms ar e unknown. Despite this, the term is often used in the literature and in clinical practice both as a clinical sign for an individual patient and as a characteristic feature of certain specific diseases. In this study a definition of relative bradycardia as a clinical sign in an i ndividual patient and a definition of relative bradycardia as a charac teristic feature of a specific disease were established based on a ref erence population comprising 673 patients with various infectious dise ases Relative bradycardia as a clinical sign in an individual patient held no predictive value regarding the likely type of infection. Relat ive bradycardia as a characteristic feature of specific disease was fo und for typhoid fever (P=0.003). Legionnaire's disease (P=0.005) and p neumonia caused by Chlamydia sp. (P=0.0005), but not for mycoplasma pn eumonia. It was not found for other pulmonary infections, infections c aused by other Salmonella sp., other extracellular Gram-negative infec tions, or viral infections. Thus, relative bradycardia as a clinical s ign has not predictive value for obtaining a tentative diagnosis, but relative bradycardia as a feature of specific disease is seen in typho id fever, Legionnaire's disease, and pneumonia caused by Chlamydia sp. It seems that relative bradycardia as a feature of specific disease o nly occurs in diseases caused by organisms that are both Gram-negative and intracellular.