Main»Endocarditis

Endocarditis

Endocarditis

1. Infective endocarditis:

A. Invasion of the endothelial surface of the heart by microorganisms
B. Infective microorganism may be:
C. Bacteria
D. Fungus
E. Rickettsia
F. Chlamydia
G. Virus
H. Commonly affects heart valves; also shunts (PDA), septal defects (VSD), coarctation of aorta

2. Predisposing Factors

A. Congenital lesions
B. Ventricular septal defects
C. Tetralogy of Fallot
D. Aortic stenosis
E. Complex cyanotic anomalies
F. Patent ductus arteriosus
G. Systemic to pulmonary arterial shunts
H. Acquired lesions
I. Rheumatic valvular disease
J. Degenerative cardiac lesions

3. Acute Infective Endocarditis

A. Toxicity marked
B. Progresses in days or weeks to valvular destruction and metastatic infection
C. Typically due to staphylococcus aureus

4. Subacute Infective Endocarditis (SBE)

A. Toxicity modest
B. Progresses over weeks to months, metastatic infection rare
C. Likely caused by streptococcus viridans, enterococci, staphylococcus epidermis, gram negative coccobacilli

5. Characteristic lesion: The Vegetation

A. A mass of platelets, fibrin and microorganisms

6. Native valve endocarditis - occurs on normal, congenitally deformed, or diseased valves

A. Aortic valve most common
B. Prosthetic valve endocarditis
C. 10-20% of cases of endocarditis
D. Greatest risk during initial 6 months after valve surgery
E. Staphylococcus epidermis most common cause
F. Often extends beyond the valve into anulus and cardiac tissues

7. Pathogenesis

A. Intact endothelium is resistant to infection
B. Injury to heart valve endothelium leads to deposition of platelets and fibrin (nonbacterial thrombotic endocarditis)
C. Platelet - fibrin complex receptive to bacterial colonization
D. Bacteremia originates most commonly from oral mucosa, genitourinary or gastrointestinal tract
E. Fibronectin binds bacteria to platelet - fibrin complex (or to normal endothelium) - The vegetation grows, sheds organisms or fragments and embolizes

8. Pathophysiology

A. Constitutional symptom of infection
B. Locally destructive effects of infection
C. Embolization of vegetation
D. Continuous bacteremia with remote infection
E. Antibody response with tissue injury (eminent complex or antibody - complement reaction)

9. Constitutional Symptoms

A. Fever 80 - 85%
B. Chills 42 - 75%
C. Anorexia 25 - 55%
D. Malaise 25 - 40%
E. Weight loss 25 - 35%

10. Locally Destructive Effects of Infection

A. Perforation of valve leaflets
B. Perforation of fistula between blood vessels or cardiac chambers
C. Abscesses
D. Disruption of conduction system

11. Signs

A. Fever 80 - 90%
B. Murmur 80 - 85%
C. Changing or new 10-40%
D. Peripheral signs
E. Petechiae 10 - 40%
F. Splinter hemorrhages 5 - 15%
G. Osler’s nodes 7 - 10% (tender subcutaneous nodules in pulp of digits)
H. Janeway lesions 6 - 10% (erythematous, nontender lesions on palm or sole)
I. Roth spots 4 - 10% (retinal hemorrhage with pole center)

12. Emboli

A. Systemic emboli with infarction occur in 40%
B. Splenic (LUQ pain)
C. Renal (flank pain)
D. Cerebral (stroke 10 - 15%)
E. Coronary (common at autopsy, transmural infection rare)
F. Mesenteric (abdominal pain, ileus)
G. Retinal (blindness 3%)
H. Pulmonary emboli, often septic, occur
I. In 75% with tricuspid valve endocarditis

13. Diagnosis

A. High index of suspicion
B. Valvular heart disease
C. Prosthetic heart valve
D. Fever
E. Murmur
F. Positive blood culture
G. Echocardiogram (TEE = 82 - 94% +)
H. Vegetation
I. Dehiscence of prosthetic valve
J. New valvular regurgitation

14. Fungal Endocarditis

A. 5% of cases of NVE
B. 10% of cases of PVE
C. Most common in IV drug abuse or underlying systemic disease
D. Diagnosis difficult, because many patients are afebrile with normal WBC

15. Fungus often difficult to culture, blood cultures typically negative

A. Large vegetations, systemic embolization, myocardial invasion, extremely resistant to medical therapy
B. Early surgical intervention warranted because medical mortality approaches 100% ->C. Anti-fungal therapy for life

16. Surgical Treatment - Absolute Indications

A. Congestive heart failure due to valve dysfunction
B. Unstable valve prosthesis
C. Uncontrolled infection
D. Persistent bacteremia
E. Fungal endocarditis
F. Relapse after optimal therapy (prosthesis)

17. Surgical Treatment - Relative Indications

A. Perivalvular extension of infection
B. Staphylococcal infection of prosthesis
C. Persistent fever (culture negative)
D. Large vegetation (> 10 mm = increased embolism)
E. Relapse after optimal therapy (native valve)

18. Treatment of Extracardiac Complications

A. Splenic abscess (3 - 5%)
B. Antibiotics
C. Percutaneous catheter drainage
D. Splenectomy
E. Mycotic aneurysm (2 - 10%, 1 - 5% cerebral)
F. Antibiotics
G. Surgery for aneurysm which expand or persist
H. Emerging operation for rupture

19. Principles of Surgical Management

A. Excision of all infected valve tissue
B. Drainage and debridement of abscess cavities
C. Repair or replacement of damaged valves
D. Repair of associated pathology: Septal defects, fistulas

20. Aortic Valve - Surgical Options

A. Infection limited to leaflets
B. Aortic valve replacement
C. Infection extends to anulus or beyond
D. Debride infected tissues
E. Drain abscesses to pericardial sac (? obliterate)
F. Replace aortic root

21. Atrioventricular Valve - Surgical Options

A. Infection limited to leaflets
B. Vegectomy
C. Repair perforations
D. Reduction annuloplasty
E. Infection extends to anulus or beyond
F. Valve replacement
G. Debride and abliterate abscesses
H. ? Tricuspid valve excision
I. (20 - 30% develop CHF)

22. Results of Surgery

A. Mortality (operative) = 15 - 20%
B. Infection of prosthetic valve during operation for native valve endocarditis = 4%
C. (12 - 16% if active endocarditis)
D. Late survival (5 years)
E. Native valve = 70 - 80%
F. Prosthetic valve = 50 - 80%