Definition

Infective endocarditis (IE) is an endovascular microbial infection of cardiovascular structures (such as native valves and atrial or ventricular endocardium) and/or intracardiac foreign bodies (such as prosthetic valves, pacemaker or intracardiac defibrillator leads and surgically created conduits). It most commonly affects sites where turbulent blood flow or endothelial damage encourages formation of platelet thrombi, offering a protected area where micro-organisms can adhere and replicate. Lesions may be friable, producing systemic emboli. Complications related to IE may necessitate critical care admission. Difficult to diagnose, IE often requires prolonged medical therapy; surgical intervention may be necessary. It is uniformly fatal if untreated.

Epidemiology

Despite modern antibiotic and surgical therapy, mortality rates remain around 25%, with death resulting primarily from congestive heart failure, sepsis and central nervous system embolic events. Historically, IE was closely linked to rheumatic heart disease, with bacteraemia of oral or dental origin the usual source of infection. But owing to a dramatic decrease in rheumatic fever in developed countries and the use of antibiotics with the emergence of antibiotic resistant organisms, the organisms causing the disease and the sites of infection have changed.

The proportion of patients with no known preexisting cardiac lesion has risen to over 50%. The advent of high-dependency care, transplant surgery and the wide range of intravascular devices have created a new population at risk of nosocomial IE.