Infective Endocarditis


Definition

It is due to microbial infection of the heart valves or the lining of cardiac chamber.
The causative organism may be bacteria fungus or rickettsia.
Streptococcus and Staphylococcus account for the vast majority of cases.

TYPES

1. Subacute endocarditis: caused by organisms of relatively low virulence. It is characterized by vegetations, embolic episodes, mycotic aneurysms, value regurgitation.
2. Acute endocarditis: caused by highly virulent and invasive organisms, can affect damage values and normal heart.
3. Post operative endocarditis: follows cardiac surgery using prosthetic materials.
4. Right sided endocarditis: occurs in IV drug users.

PREDISPOSING FACTORS

1. Prosthetic heart valves.
2. Congenital cyanotic heart disease
3. Surgically constructed systolic pulmonary shunts.
4. Previous bacterial endocarditis
5. Procedures like tonsillectomy, bronchoscopy and sclerotherapy.
6. Procedures like dental extraction, dental implant placement, root canal treatment.
7. Prostatic surgery, cystoscopy, urethral dilatation.
8. Organisms like Staphylococcus aureus, Enterococcus faecalis, Streptococcus bovis, pseudomonas, Candida, Pneumococcus, Neisseria gonorrhoea.

PATHOGENESIS

1. Vegetations are fibrin platelet bacterial complex, they have 3 layer. Inner RBC, WBC, platelets. Middle of bacterial. Outer of fibrin.
2. Embolization vegetations get detached and embolize. They may be septic or sterile. Occur in kidney, brain and spleen.
3. Deposition of immune complexes.

image showing endocarditis
Endocarditis

CLINICAL FEATURES

– Ill health, fatigue, lassitude, loss of appetite, loss of weight.
– Fever with chills and rigors.
– Clubbing in fingers.
– Splenomegaly.
– Brown pigmentation of face and limbs.
– Changing murmurs.
– Worsening of cardiac failure.
– Development of MR and TR.
– LVF and pulmonary edema.
– Nails splinter hemorrhages.
– Cutaneous embolus: anyway lesions on palm and soles.
– Osler’s nodes: painful tender swollen nodules in finger pulp.
– Roth’s spots: circular retinal hemorrhages.

INVESTIGATIONS

– Normocytic normochromic anemia.
– Leukocytosis
– Hematuria and albuminuria.
– Raised ESR and CRP
– Blood culture: both aerobic and anaerobic.
– Hyperglobulinemia, positive rheumatoid factor, reduction in complement levels.
Echocardiography detect valve lesions, chamber dilatation.

Duke criteria

It has 80% sensitivity for diagnosis.
1. Major criteria
– Blood culture positive for Viridans streptococci, Streptococcus bovis, Staphylococcus aureus.
– Microbes consistent from persistently positive blood cultures defined as 2 positive cultures of blood samples drawn >12 hrs. apart.
– Single +ve blood culture for coxiella burnetii.
– Evidence of endocardial involvement by echocardiogram
– New valvular regurgitation.

2. Minor criteria
– Fever, temp>38.
– Predisposing heart condition, injectable drug use.
– Immunologic phenomenon.
– Vascular phenomenon.

TREATMENT

1. Medical
– Benzylpenicillin 3-4 million units IV 6 hourly and gentamycin 3 mg IV once a day for 2 weeks.
– Vancomycin 30mg/kg/day and gentamycin.
– For candida amphotericin is used.

2. Surgical treatment
– Progressive cardiac failure from valve damage.
– Endocarditis of prosthetic valve.
– Large vegetation.
– Abscess formation, perivalvular involvement and fungal endocarditis.

PROPHYLAXIS

  • Patient not allergic to penicillin.
  • Amox 3g orally 1 hr before procedure.
  • Patient allergic to penicillin.
  • Clindamycin 600mg orally or cephalexin 2 gm orally.