38: Surgical Treatment of Endocarditis

Epidemiology

• The overall incidence of infective endocarditis in the general population ranges from 3 to 11 cases per 100,000 person-years. The most common underlying conditions are native valvular heart disease, previously implanted prosthetic valves and congenital heart disease. Endocarditis is more common in the elderly and males. The increasing use of indwelling intravenous catheters and leads for cardiac rhythm devices is associated with iatrogenic endocarditis.

Pathophysiology

• There are five distinct steps in the sequence of events resulting in endocarditis. First, there is damage to the endocardial surface of the valve or other cardiac structure. Second, there is the accumulation of thrombus and platelets on the damaged surface, termed nonbacterial thrombotic endocarditis (NBTE). Third, the patient develops a transient blood stream infection, usually bacteremia. Fourth, there is deposition and adherence of infectious organisms on the focus of NBTE. Fifth, the organisms grow and multiply at the NBTE site.

Clinical Features

• The clinical presentation of endocarditis depends upon the rapidity of onset, the virulence of the underlying organism, and the coexistence of underlying cardiac disease. Patients with acute endocarditis usually present early in the infection with substantial illness. Complications are common and are due to embolism and valvular destruction. Such complications include brain embolism, intracranial hemorrhage, heart failure, myocardial infarction, and peripheral embolism.

Diagnostics

• Physical examination, blood cultures and echocardiography are the cornerstones for the diagnosis of endocarditis. Adherence to the major and minor criteria of the modified Duke classification guide diagnosis and subsequent management. Transthoracic echocardiography is usually sufficient to identify the vegetation, but transesophageal provides the optimal method for establishment of endocarditis according to the Duke major criteria.

Treatment

• Prompt and accurate antimicrobial therapy should be initiated for the patient with endocarditis. In general, antibiotic therapy will be administered intravenously in high dosages for a prolonged period of time. The primary goals of operation for endocarditis are removal of all infected tissue and correction of the hemodynamic abnormality. Infection of a cardiac valve necessitates either repair or replacement.

Outcome

• Mortality after operation for endocarditis ranges widely, with reports of hospital death between 4 and 30 percent. In general, operative mortality is affected by the urgency of the operation, concomitant preoperative heart failure, nonstreptococcal organisms, and prosthetic valve endocarditis. Neurologic deficits can be worsened if surgery is performed within the first few weeks after the initial event. Recurrent endocarditis is uncommon (2–5 percent) if all infected tissue has been removed and there is no active infection at the time of operation.