In infective endocarditis, fibrin and platelets cluster on valve tissue and engulf circulating bacteria or fungi. This produces vegetation, which, in turn, may cover the valve surfaces, causing deformities and destruction of valvular tissue. It may also extend to the chordae tendineae, causing them to rupture and leading to valvular insufficiency.

Sometimes vegetation forms on the endocardium, usually in areas altered by rheumatic, congenital, or syphilitic heart disease. It also may form on normal surfaces. Vegetative growth on the heart valves, endocardial lining of a heart chamber, or the endothelium of a blood vessel may embolize to the spleen, kidneys, central nervous system, and lungs.

Endocarditis can be classified as native valve endocarditis, endocarditis in LV. drug users, and prosthetic valve endocarditis. It can be acute or subacute. Untreated, endocarditis is usually fatal. With proper treatment, however, about 70% of patients recover. The prognosis is worst when endocarditis causes severe valvular damage - leading to insufficiency and left-sided heart failure or when it involves a prosthetic valve.

Causes of Endocarditis

Acute infective endocarditis usually results from bacteremia that follows septic thrombophlebitis, open-heart surgery involving prosthetic valves, or skin, bone, and pulmonary infections.

The most common causative organisms are group A nonhemolytic streptococci, staphylococci, and enterococci. However, almost any organism can cause endocarditis, including Neisseria gonorrhoeae, Pseudomonas. Salmonella. Streptobacillus. Serratia marcescens. bacteroids. Haemophilus. Brucella, Mycobacterium. N. men ingitidis. Listeria, Legionella, diphtheroids, enteric gramnegative bacilli, spirochetes, rickettsiae, chlamydiae, and the fungi Candida and Aspergillus.

Subacute infective endocarditis typically occurs in people with acquired valvular or congenital cardiac lesions. It can also follow dental, genitourinary, gynecologic, and GI procedures. The most common infecting organisms are Streptococcus viridans, which normally inhabits the upper respiratory tract, and Streptococcus faecalis (enterococcus), which is typically found in GI and perineal flora.

Preexisting conditions can predispose a person to endocarditis (including rheumatic valvular disease), congenital heart disease, mitral valve prolapse, degenerative heart disease, calcific aortic stenosis (in elderly people). asymmetrical septal hypertrophy, Marfan syndrome, syphilitic aortic valve, I. V. drug abuse, and long-term hemodialysis with an arteriovenous shunt or fistula. However, up to 40% of affected patients have no underlying heart disease

Signs & Symptoms of Endocarditis

Endocarditis can cause a variety of symptoms, particularly in the early stages of infection. Patients may experience general symptoms such as the following:

Chills
Cough
Heart murmur
Fever
Fatigue
Night sweats, may be severe
Loss of appetite
Muscle aches and joint pain
Sweating, excessive
Paleness
Weight loss

These vague symptoms can make it difficult for the patient and the doctor to recognize endocarditis.

As infection progresses, other symptoms may develop. If the infection damages the heart valve, the valve may become "leaky." A leaky heart valve eventually can cause blood to back up into the lungs, resulting in shortness of breath. If the infection spreads to the kidneys, patients may experience blood in the urine (hematuria). If the infection spreads to the brain, it can cause headaches, confusion, or stroke.

Diagnostic Tests

Three or more blood cultures during a 24- to 48-hour period identify the causative, organism in up to 90% of patients. The remaining 10% may have negative blood cultures, possibly suggesting fungal or difficult-todiagnose infections such as Haemophilus parainjluenzae. Other abnormal but nonspecific laboratory results include:

normal or elevated white blood cell count and differential
abnormal histiocytes (macrophages)
normocytic, normochromic anemia (in subacute E infective endocarditis)
elevated erythrocyte sedimentation rate and serum creatinine levels
positive serum rheumatoid factor in about half of all patients with endocarditis after the disease is present for 6 weeks
proteinuria and microscopic hematuria.

Echocardiography may identify valvular damage in up to 80% of patients with native valve disease. An electrocardiogram reading may snow atrial fibrillation and other arrhythmias that accompany valvular disease.

Treatment

The goal of treatment is to eradicate all of the infecting organisms from the vegetation. Therapy should start promptly and continue over several weeks. Selection of an antiinfective drug is based on the infecting organism and sensitivity studies. Although blood cultures are negative in 10% to 20% of the subacute cases, the doctor may want to determine the probable infecting organism. l.v. antibiotic therapy usually lasts about 4 to 6 weeks.

Supportive treatment includes bed rest, aspirin for fever and aches, and sufficient fluid intake. Severe valvular damage, especially aortic insufficiency or infection of a cardiac prosthesis, may require corrective surgery if refractory heart failure develops or if an infected prosthetic valve must be replaced.

Prevention Tips

Preventive antibiotics are often given to people with predisposing heart conditions before dental procedures or surgeries involving the respiratory, urinary, or intestinal tract. Continued medical follow-up is advised for people with a history of endocarditis.

Maintaining good oral hygiene by brushing and flossing regularly and by having periodic dental examinations also may help reduce the risk for endocarditis.

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