Infective Endocarditis

1. Infective Endocarditis

2. Is due to microbial infection of a heart valve, the lining of cardiac chamber or blood vessel, or a congenital anomaly (septal defect). • The causative agent is usually abacterium, but may be any organisms.

3. Pathophysiology • Typically occurs at site of pre-existing endocardial damage. • But virulence organism like staph.aureus can affect normal valve. • Tricusped valve endocarditis in i.v. drug abuser. • Defect associated with high jet like PDA and VSD > liable while defect with low jet less likely as in ASD. • Vegetation (organism,fibrin & platelete). • Extracardiac manifestations such as vasculitis & skin lesion are due to emboli or immune complex deposition.Mycotic aneurysm may develop in arteries at sites of emboli .

4. Microbiology • *Streptococci ; • Viridans gr. 30-40 %. • Entrococci 10-15 %. • Other streptococci 20-25 %. • *Staph. : • Staph.aureus 9-27 % • Coagulase –negative 1-3 % • *Gram –ve, Haemophilus & Anaeroes 3-8 %. • *Rickettsiae & fungi < 2 %.

5. Clinical features • Could be divided in to Acute and subacute with overlap between them . • The clinical pattern influenced by the type of organism, the site of infection and prior antibiotic therapy . • Sub acuteBacterial Endocarditis : persistent fever, un usual tiredness, night sweating or weight loss ,or new signs of valve dysfunction or heart failure.Less often embolic phenomenon. • Osler nodes a painfull tender nodes at finger tips probably due to vasculitis (rare). • Digital clubbing is a late sign . • The spleen frequently palpable .In Qoxiella infection the spleen and liver may be considerably enlarged..Microscopichaematuria is common.

8. Acute endocarditis : sever febrile illness, with prominent and changing murmur and petichiae . Embolic phenomenon is common , and cardiac and renal failure may develop rapidly. Abscesses may be detected on echocardiography.clinical features of chronic endocarditis usually abscent.

9. Post operative endocarditis : any un explained fever in a patient who has had heart valve surgery should be investigated for possible endocarditis. The infection usually affect valve ring & may resemble sub acute or acute endocarditis, depending on virulence of the organism. Morbidity and mortality is high and redo surgery usually required.

10. Investigations: • Blood culture :3 samples for culture should be obtained on aseptic technique on different sites, aerobic and anaerobic culture are required . • Echocardiography :Is the key tool for detecting vegetations and following its progress, as small as 3-5 mm can be detected on TTE and as smaller as 1-1.5 mm on TEE. the later specially important in identifying abscess formation and endocarditis of the prosthetic valve. • Elevation of ESR and a normochromic ,normocytic anaemia ,with leuckocytosis are common. • Measurement of CRP(C-reactive Protein ) is more reliable for monitoring the treatment than ESR. • Proteinurea & microscpichaematuria may occur and usually is the only positive finding. • ECG is important t for monitoring the development of conduction defect and aortic root abscess by showing P-R prolongation. • Chest X-ray show evidence of cardiac failure and cardiomegaly.

11. Management • Mortality rate is about 20 % and may be higher in special cases (prosthetic valve endocarditis and resistant microorganism). • A 2 week treatment regimen may be sufficient for fully sensitive strains of Streptococcal viridans and Strep.bovis. • For empirical treatment of bacterial endocarditis ,Penicillin plus gentamicin is the treatment of choice for most of the cases. • However when staphylococcal infection is suspected vancomycin plus gentamicine is recommended.

12. Cardiac surgery (debridement of infected material & valve replacement) is advisable for the following conditions ; • 1-Heart failure due to valve damage. • 2-failure of antibiotic therapy. • 3-Large vegetation on left sided valve. • 4-Abscess formation. • 5-prosthetic valve endocarditis. • 6-Fungal endocarditis.