INFECTIVE ENDOCARDITIS (IE)

INFECTIVE ENDOCARDITIS (IE)

It is the colonisation of the heart valves with microbiological organisms, leading to the formation of friable, infected vegetations and frequently valve injury.

Types

1. ACUTE INFECTIVE ENDOCARDITIS : caused by highly virulent organisms mainly Staphylococcus Aureus (20-30%), seeding a previously normal valve.
2. SUBACUTE INFECTIVE ENDOCARDITIS : caused by organisms of moderate or low virulence mainly STREPTOCOCCI (60-70%), seeding an abnormal or previously injured valve.
3. ENDOCARDITIS OCCURING IN I/V DRUG ABUSERS : caused predominantly by organisms found on the skin (S. aureus, Candida) and affecting the valves on the right side of the heart.
4. PROSTHETIC VALVE ENDOCARDITIS : This may be early ( symptoms appearing within 60 days of valve insertion ), due to intraoperative infection of the valve or insertion of an infected valve or late ( after 60 days of valve insertion), due to late bacteremia.

Predisposing factors to developement of IE

• Congenital cardiac anomalies (shunts or stenosis with jet streams)
• Rheumatic heart disease
• Mitral valve prolapse
• Degenerative calcific stenosis
• Bicuspid aortic valve
• Prosthetic valves
• Indwelling catheters.

Clinical Manifestations

Symptoms

• Fever
• Malaise
• Fatigue
• Anorexia.

Signs

• Clubbing
• Splenomegaly
• Pallor (anaemia)
• Heart murmurs ( esp. regurgitant murmurs, or changing murmur)
• Petechiae (seen after 6 weeks over conjunctiva, buccal mucosa, palate and skin above clavicle)
• Splinter subungual haemorrhages
• Osler nodes (small tender nodules, on the fingers or toe pads as a result of septic emboli and immune complex deposition)
• Janeway lesions (1-4 mm non-tender erythematous macules over palms and soles due to septic emboli)
• Roth's spots : oval retinal haemorrhages with a pale centre.
• Arthralgia or arthritis.

Lab Diagnosis

Blood culture

• At least 3 blood culture samples and maximum of 6 culture samples to be taken.
• Each samples to be collected from different venipuncture sites and after 30 min to 1 hour gap to demonstrate continuous bacteraemia.
• At least 10 ml of blood to be obtained for culture and diluted 10 fold in culture medium.
• Culture to be done for both aerobic and anaerobic organisms.
• Yield of positive culture increased by observing them over 3 weeks and making periodic subcultures.
• Presumptive antibiotics to be started immediately after obtaining culture samples.

NEGATIVE BLOOD CULTURE IN IE

• Infection with fastidious organisms (H.parainfluenza, Brucella)
• Anaerobic infection
• Candida, Aspergillus, Histoplasma, Coxiella burnetii, Chlamydia psittaci endocarditis
• Inadequate quantity of blood sample for culture or inadequate amount of culture media
• Prior antibiotic therapy
• Right sided endocarditis.

2D ECHO

• The smallest size of vegetation that can be picked up by echo is 2 mm.
• Transeosophageal echocardiography is more sensitive in detecting vegetations in the aortic valve and mitral valve than transthoracic echocardiography.

DUKE'S CRITERIA

MAJOR CRITERIA : 

1. Positive blood culture
2. Involvement of endocardium

MINOR CRITERIA : 

1. Predisposition (cardiac lesion, IV drug abuse)
2. Fever >38°C
3. Vascular or immunological signs
4. Positive blood culture - that does not meet major criteria
5. Positive echo - that does not meet major criteria

DIAGNOSIS :

Diagnosis confirmed by 2 major / 1 major + 3 minor / all 5 criteria.

INFECTIVE ENDOCARDITIS TREATMENT

• Inj. Benzyl penicillin 20 to 40 lakh units IV 4 hourly for 4 weeks.
• Parenteral aminoglycosides (SM, GM, Amikacin) given in appropriate divides doses for the first 2 weeks.
• Appropriate antibiotic changes may be made on receiving the results of blood culture.

PROPHYLAXIS IN IE

Capsule Amoxycillin 3 gm orally, 1 hour before the procedure and 1.5 gm orally 6 hours after the first dose.

INDICATIONS FOR SURGICAL MANAGEMENT

• Failure of medical treatment as indicated by persistent positive blood culture or refractory failure
• Myocardial or valve ring abscess
• Aortic valve endocarditis developing heart block
• Prosthetic valve endocarditis
• Presence of large vegetation with possible embolism
• Fungal endocarditis.

Some important images of signs

clubbing

splinter haemorrhage

roth's spot