Monday, January 08, 2007

Infective Endocarditis in MRCP

Infective Endocarditis in MRCP

Today I would like to discuss about infective endocarditis which is defined as infection of the endothelial surface of the heart. It is a common condition asked in MRCP!A heart valve is always involved but the infection may develop on a septal defect or on the mural endocardium.

Generally, it is useful to classify endocarditis into these three subtypes,

1) Native valve endocarditis- endocarditis develops in native valves. Patients developing native valve endocarditis usually have valvular heart lesion. Common valvular heart lesions that prone patient to get endocarditis include mitral valve lesions ( incompetence and stenosis), aortic valve lesions ( incompetence and stenosis)

2) Endocarditis in Intravenous Drug Abusers- usually IVDUs develop right heart endocarditis ( Tricuspid Valve) due to direct septic emboli to the right heart from peripheral vein.

3) Prosthetic Valve Endocarditis- Endocarditis develops in prosthetic valves. It is easier for you to remember the causative organisms if you divide Prosthetic valve endocarditis into early or late. For early onset Prosthetic valve endocarditis ( onset of symptoms within 2 months post valve replacement), the causative agent is mainly S.epidermidis. Late onset Prosthetic valve endocarditis usually happens post instrumentation in patients with prosthetic valve.

Signs and Symptoms of Infective Endocarditis

Patients may present with fever, lethargy ( may be due to anemia), unexplained weight loss, chest pain, confusion

Always remember about stigmata of infective endocarditis- Janeway lesion ( non- tender), Osler’s nodes (tender), splinter haemorrhages, Roth Spots and petechiae( due to septic emboli)
Splenomegaly
Murmurs
Clubbing
Fever


(A-splinter haemorrhage, B-Conjunctival petechiae, C-Osler's node, D-Janeway's Lesion)


( There is a criteria for you to diagnose Infective Endocarditis known as Durack’s criteria, you do not need to know about the details, however, remember that the two major criteria are positive isolation of organisms from blood culture and evidence of endocardial involvement on ECHO)

Investigations
Full blood count- raised TWC and anemia ( normocystic, normochromic), raised ESR
Haematuria may be present in 50% of cases
Blood culture ( remember that you may need CO2 culture for fastidious HACEK organisms-Haemophilus, Actinobacillus,Cardiobacterium,Eikenella and Kingella)

Complications
Mainly due to septic emboli- the emboli can go to brain, spleen, liver, lung leading to abscess formation. In the heart, infective endocarditis can cause valvular failure, heart block and prosthesis failure!

Treatment
Prolonged IV antibiotics ( up to 4-6 weeks) , usually combination of IV penicillin + gentamycin.
Surgery is indicated if development of fungal endocarditis, valve dehiscence, heart block, valve ring abscesses, failure of medical treatment!


Tips for MRCP
1) Remember patients with what valvular heart lesions need antibiotics prophylaxis before invasive procedures. Click here to find out more!

2) Remember what do you mean by invasive procedures, click here to learn more!

1 comment:

manu said...

What is Infective Endocarditis?

Infective endocarditis is a form of endocarditis caused by infectious agents. Agents are usually bacteria, but other agencies may also be responsible. Heart valves do not receive the blood supply is engaged. Consequently, immune defense mechanisms (such as white blood cells) can not directly reach the valve through the bloodstream.

http://heart-consult.com/articles/what-infective-endocarditis