The symptoms and signs of endocarditis are often constitutional and, when localized, often result from a complication of IE rather than reflect the intracardiac infection itself. Consequently, inorder to avoid over looking the diagnosis of IE, a high index of suspicion must be maintained. The diagnosis must be investigated when patients with fever present with one or more of the cardinal elements of IE: a predisposing cardiac lesion or behaviour pattern, bacteremia, embolic phenomenon, and evidence of the active endocardial process. Because patients with prosthetic heart valves are always at risk for PVE, the presence of fever or new prosthesis dysfunction at any time warrants considering this diagnosis. Even when the illness seems typical of endocarditis, the definitive diagnosis requires positive blood cultures or positive cultures (or histology or polymerase chain reaction recovery of a microorganism's DNA) from the vegetation or embolus.