Infective endocarditis occurs when there is infection of the inner layer of heart muscle (endocardium); with heart muscle, the myocardium has the largest bulk.

Infection of the endocardium usually involves the heart valves, where vegetative growths develop. Small pieces of these vegetations may break free and embolise to the brain causing a stroke.


Why does this happen and how may it affect the patients health?

Conditions that may lead to infection of the endocardium are

  • Complications of heart surgery
  • Birth defects of heart valves
  • Rheumatic fever
  • Indwelling catheters and intravenous lines
  • Intravenous drug users

There are a number of infective organisms that may cause infective endocarditis, but most commonly it is caused by Streptococcus viridans (50 to 75%), secondary to

  • Complications of ear, nose and throat infections, or
  • Dental surgical procedures

What symptoms may the patient experience?

  • A general unwell feeling
  • There may be a history of sudden deterioration by the patient from an initial ear, nose or throat infection
  • Fever
  • Heart failure develops secondary to ineffective heart valve functioning (secondary to valve damage), or fever (causes increased heart rate which tires the patient), or anaemia (low levels of red blood cells and haemoglobin)
  • There may be heart murmurs audible on examination with a stethoscope
  • The spleen may enlarge and become painful
  • Fingers may enlarge on the tips (clubbing of fingers)
  • Tender nodules may develop on the fingers (Oslers nodes) - examine pulp area of fingers
  • Kidney problems develop secondary to infarcts (areas of tissue death in the kidneys)
  • There may be evidence of patches of bleeding under the skin called petechiae and small splinter haemorrhages (bleeding) under the nails

How is the diagnosis made and what special investigations are required?

Complete blood count (increased white blood cells and reduction in red blood cells and haemoglobin; anaemia).

ESR (erythrocyte sedimentation rate) is increased.

Examination of urine (shows blood in urine).

Culture and sensitivity of blood may show evidence of the infective organism responsible for causing the endocarditis.

What is the treatment and prognosis?

Intravenous antibiotics to start with; this may have to be continued for an extended period if necessary.

The patient will have to take antibiotics on a regular basis after the condition has been resolved (prophylactic measures) in order to prevent a recurrence. Antibiotics for prophylaxis include

  • Erythromycin
  • Amoxycillin
  • Amphotericin B (for fungi)
  • Vancomycin
  • Gentamycin

This is a serious condition and the prognosis depends on

  • How quickly the endocarditis can be brought under control
  • The underlying cause
  • The extent of the heart failure
  • To what extent the heart valves were damaged in the process

It may be necessary to surgically replace damaged heart valves.

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