Overview of Endocarditis

Endocarditis is an infection of a heart valve or the inner lining of the heart (the endocardium). Infection can damage or destroy the heart valves and damage the heart. Endocarditis usually occurs in patients with congenital (i.e., present at birth) or acquired heart conditions (e.g., atrial septal defects, valve disease).

Although several different organisms can cause endocarditis, it is usually caused by bacteria. In most cases, it develops when normal bacteria on the skin or in the respiratory, gastrointestinal, or urinary tract enter the bloodstream and lodge within a damaged heart valve or abnormal heart tissue. Untreated, this bacterial infection gradually damages the endocardium and causes the heart valve to malfunction. Infection can spread to the bloodstream (septicemia) and to other parts of the body.

Incidence & Prevalence of Endocarditis

Endocarditis is more common in older people. About 50% of all cases occur in patients over the age of 50. Endocarditis is twice as common in men of any age and is 8 times as common in elderly men as in elderly women.

In children and young adults, most cases (about 75%) of endocarditis occur in those with congenital (i.e., present at birth) heart defects.

Endocarditis Causes & Risk Factors

Most cases of endocarditis are caused by a bacterial infection. Patients who have a congenital or acquired heart condition have an increased risk for endocarditis. The condition is rare when heart disease is not present.

The following heart conditions increase the risk:

  • Atrial septal defect (i.e., hole in the wall between the upper chambers of the heart)
  • Prior endocarditis
  • Prosthetic heart valve
  • Surgical shunt from aorta to pulmonary artery
  • Ventricle defect

There are many ways that bacteria can enter the bloodstream and cause endocarditis. Even a small cut can enable bacteria that normally live on the skin to enter the bloodstream. In some cases, this occurs during a dental or surgical procedure. In many cases, however, it is not clear how the bacteria first got into the bloodstream.

Procedures that increase the risk for endocarditis include the following:

  • Adenoidectomy (surgical removal of the adenoids)
  • Dental cleaning
  • Endoscopic examination or surgery of the respiratory, gastrointestinal, or urinary tract
  • Tonsillectomy (surgical removal of the tonsils)

In hospitalized patients, intravenous lines (IVs) and catheters can introduce bacteria into the blood. Using contaminated needles to inject illegal drugs into the bloodstream increases the risk for endocarditis, and some sexually transmitted diseases (STDs; e.g., chlamydia, gonorrhea) also increase the risk.

Fungal infection is a rare cause of endocarditis in patients with compromised immune systems, such as people with HIV/AIDS and those who have undergone chemotherapy.

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
  • Fever
  • Fatigue
  • Loss of appetite
  • Muscle aches and joint pain
  • Sweating
  • 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.

Complications of endocarditis include the following:

  • Cardiac arrhythmia (e.g., tachycardia, bradycardia, atrial fibrillation)
  • Congestive heart failure (CHF)
  • Heart attack (myocardial infarction)
  • Pericarditis (inflammation of the lining that surrounds the heart)

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 30 Jun 2000

Last Modified: 14 Sep 2015