Infective endocarditis (prosthetic valve)

Infections of prosthetic valves accounts for 15-30% of cases of endocarditis. Most are males over 60 years of age. Aortic valve prostheses are affected more commonly than mitral valve ones.

Two presentations are recognised:

• early-onset - develops within 60 days of surgery and is due to infection of the prosthesis during surgery or to bacteraemia peri-operatively. It is usually associated a fulminant course. Staphylococci account for about 50% of cases, usually, Staph. epidermidis. Gram negative bacilli and fungi are common. Streps. are rare. Mortality is between 30% and 70%.
  
  
• late-onset - symptoms develop after 60 days from surgery and is due either to subsequent bacteraemia or to a preceeding infection with a long incubation period. 40% of cases are due to Streptococci. Staphylococci occur in about one-third of cases. Mortality is between 20% and 30%.

Valve dysfunction is a common feature caused by large vegetations which prevent opening and closure. Often, there are myocardial abscesses producing heart block, arrhythmias, and emboli.

The investigation, treatment etc. of prosthetic valve endocarditis is considered together with the other forms of endocarditis.