INFECTIVE ENDOCARDITIS

Infection of the endocardial surface of the heart – valve (native or prosthetic), heart chamber or a

congenital anomaly.

Two types:Acute – Fulminating infection Insidious – Subacute Bacterial Endocarditis

Bacteria, Rickettsia, Chlamydia or Fungi

Without treatment - 100% mortalityEven with treatment significant morbidity & mortality

Etiology:

Two factors:

1) Presence of organisms in the blood stream

2) Abnormal cardiac endothelium facilitating adherence and growth of bacteria

Factors causing Bacteremia:

• Poor dental hygiene

• IV drug abuse

• Soft tissue infection

• Iatrogenic – dental treatment, intravascular cannulae, cardiac surgery or permanent pacemakers

Genesis of vegetations:

• Damaged vascular endothelium promotes platelet and fibrin deposition.

• These small thrombi allow organisms to adhere and grow.

• More fibrin and platelets are deposited leading on to a infected vegetation.

Damaged vascular endothelium – can result from lesions that cause high pressure jet flow of blood.

Eg) AR, MR, VSD, PDA

Right heart endocarditis – occurs in IV drug abuse, placement of central venous catheter, temporary pacemaker.

Organisms responsible:

Alpha hemolytic streptococci – usually from the oral cavity (Streptococcus Viridans)

Staphylococcus & Candida - through skin following IV cannula & IVDA

Enterococci – in GU and GI related procedures and diseases

HACEK organisms - living on dental gums

Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella

Culture negative endocarditis - occurs in 5 to 10%.

May be due to previous antibiotic therapy.

May be due to organisms failing to grow in normal cultures – Coxiella burneti, Chlamydia, Bartonella, Legionella

Clinical Presentation:

Two types: 1) Acute illness 2) Subacute insidious illness.

Clinical signs due to following processes: 1) Systemic features of infection 2) Cardiac lesions 3) Vascular phenomena (embolization) 4) Immunological phenomena (Immune

complex deposition - vasculitis)

General: Malaise, Clubbing, Arthralgia, PyrexiaCardiac: new murmur, signs of failure, conduction block

due to perivalvular abscess, MISkin lesions: Osler’s nodes, Splinter hemorrhages,

Janeway lesions, Petechiae Eyes – Roth spots, Conjunctival splinter hemorrhagesNeurological: Cerebral emboli, Mycotic aneurysmSplenomegaly (40%), Renal – Hematuria, Peripheral embolism: Spleen, Kidneys, Brain, Bowel

Investigations:

Blood culture - Minimum of 3 samples from 3 different sites (gap of 1 hour between first and last sample). For Atypical organisms – over 24 hours.

Complete blood countLiver function, Renal function, ElectrolytesInflammatory markers – ESR, CRPUrine – hematuriaImmunoglobulins – increasedComplement level – decreasedECG (MI or AV block), CXR, Echo – TTE, TOE

Duke’s criteria:

Diagnosis of IE made if there are 2 major (or) 1 major and 3 minor (or) 5 minor criteria.

Major criteria: (1) Positive blood culture. Typical organisms in two separate samples or persistently positive culture for atypical organisms in samples drawn 12 hours apart. (2) Evidence for endocardial involvement. Echo finding of oscillating intracardiac mass, new valvular regurgitation, abscess, partial dehiscence of prosthetic valve

Minor criteria: Fever, Predisposing heart lesion, Immunological phenomena, Vascular phenomena

Treatment:

Principles: Difficult to treat because organisms reside within a avascular protected site within vegetations.

High concentration of IV antibiotics required for prolonged duration for a successful outcome.

Empirical antibiotic treatment started after cultures are taken. Regimen adjusted according to culture results. Treatment continued for 4 to 6 weeks.

Usually - Penicillin 1.2 g 4 hrly and Gentamicin 80 mg 12 hrly started. Vancomycin 1 g 12 hrly, if allergic to penicillin.

Indications for surgery:

• Extensive damage to valve• Prosthetic valve endocarditis• Persistent infection despite therapy• Large vegetations• Serious embolization• Myocardial abscess • Fungal endocarditis• Progressive cardiac failure

S. Aureus mitral valve vegetation, anterior leaflet

Roth spot

Janeway lesion