Infective Endocarditis

Infective endocarditis is an infection of the heart's inner surface, typically affecting the valves. The primary cause is bacterial infection, though fungal infections can also occur.

Common symptoms include fever, small areas of bleeding into the skin, heart murmur, fatigue, and low red blood cell count. Complications can include valvular insufficiency, heart failure, stroke, and kidney failure.

Classification

Infective endocarditis is classified by the duration of symptoms into acute, subacute, and chronic forms. Acute endocarditis presents within days to six weeks, subacute lasts between six weeks to three months, and chronic persists beyond three months.

The condition can also be categorised based on culture results (culture-positive or culture-negative), the side of the heart affected, the infection setting, and the type of valve involved (native or prosthetic).

Causes and Risk Factors

The predominant cause of infective endocarditis is bacterial infection, most commonly by streptococci and staphylococci. Risk factors include valvular heart disease, congenital heart disease, artificial valves, hemodialysis, intravenous drug use, and electronic pacemakers.

Signs and Symptoms

Typical signs and symptoms of infective endocarditis include:

• Fever (97% of cases)
• Malaise and fatigue (90%)
• New or changing heart murmur, weight loss, and coughing (35%)

Vascular phenomena can include septic embolism, Janeway lesions, and splinter haemorrhages. Immunologic phenomena may present as glomerulonephritis, Osler's nodes, and Roth's spots.

Diagnosis

Diagnosis relies on the Duke criteria, which combine clinical, microbiological, and echocardiographic findings. Blood cultures are essential for identifying the causative organisms.

Echocardiography, particularly transesophageal echocardiography (TEE), is very important for detecting valvular vegetations and assessing the extent of infection.

Treatment

High-dose intravenous antibiotics are the cornerstone of treatment, tailored based on blood culture results. Empirical antibiotic therapy is initiated in acute cases until specific pathogens are identified.

In cases where antibiotic therapy is insufficient, surgical intervention may be necessary, particularly for significant valvular damage, heart failure, or persistent infection.

Prognosis and Epidemiology

Infective endocarditis has a significant mortality rate, with about 25% of affected individuals dying from the condition. The incidence is approximately 5 per 100,000 people per year, with higher rates in older adults and males.

Improved diagnostic and treatment methods have increased the survival rates, especially in patients with congenital heart disease.

Understanding infective endocarditis is very important for healthcare professionals, including dentists, who may encounter patients at risk for this condition, particularly those with underlying heart diseases or a history of intravenous drug use.

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Self-assessment MCQs (single best answer)

What is the most common cause of infective endocarditis?

Which of the following is NOT a common symptom of infective endocarditis?

Which microorganism is most commonly associated with infective endocarditis in intravenous drug users?

Which diagnostic method is essential for identifying the causative organisms in infective endocarditis?

What imaging technique is most sensitive for detecting valvular vegetations in infective endocarditis?

Which of the following is a major criterion in the Duke criteria for diagnosing infective endocarditis?

Which of the following is a common complication of infective endocarditis?

What is the primary treatment for infective endocarditis?

Which organism is most commonly responsible for prosthetic valve endocarditis?

What is the main indication for surgical intervention in infective endocarditis?