INFECTIVE ENDOCARDITIS Manoj Kuduvalli

Definition Bacterial or Fungal infection within the heart (although chlamydial and rickettsial infections are known) ; the role of viruses is unknown

ORIGINAL CLASSIFICATION (Prior to Antibiotic era)

Current Criteria for Classification Underlying Anatomy: › Native Valve Endocarditis › Prosthetic Valve Endocarditis Infecting Organism › Serves as basis for therapy and prognosis

Native Valve Endocarditis Underlying Predisposing Conditions ›› 60 - 80% of non IV Drug abusers have a predisposing condition › Mitral Valve Prolapse 30 - 50% › Rheumatic Heart Disease 20 - 40% › Degenerative Aortic and 20 - 30% Mitral valve disease › Congenital Heart Disease 10 - 20%

Native Valve Endocarditis Microbiology ›› Streptococci 50 - 70% Viridans Streptococci (50% of all Strep) ›› Staphylococci ~ 25% Mostly Coagulase +ve Staph. Aureus Staph. Epidermidis ›› Enterococci ~ 10%

Native Valve Endocarditis Microbiology Viridans Streptococci Infect primarily abnormal valves Indolent clinical course Highly sensitive to Penicillins Staph. aureus Infect normal and abnormal valves Fulminant course with rapid destruction of valves and multiple metastatic abscesses Mostly resistant to Penicillins and sensitive to penicillinase resistant ß-lactams Common with soft tissue infections, and infected IV catheters

Native Valve Endocarditis Microbiology Staph. Epidermidis Indolent Course Affects abnormal valves Enterococci Normally affects damaged valves Recent history of genitourinary or gastrointestinal manipulation, disease or trauma Usually sensitive to Penicllin+Gentamicin Resistant strains prevalent

Prosthetic valve endocarditis 5 - 15% of all Infective Endocarditis Overall incidence 1 - 4% Risk of PVE peaks at 15 days postop. , then rapidly declines by 150 days

Prosthetic Valve Endocarditis Classification Early ( < 60 days ) Reflects perioperative contamination Incidence around 1% Microbiology Staph (45 - 50%) Staph. Epiderm (~ 30%) Staph. Aureus (~ 20%) Gram -ve aerobes (~20%) Fungi (~ 10%) Strep and Entero (5-10%) Late ( > 60 days) After endothelialization Incidence 0.2 -0.5 % / pt. year Transient bacteraemia from dental, GI or GU Microbiology resembles native valve endocarditis

IE in IV Drug Abusers Right sided predilection Tricuspid Valve ~ 55% Aortic Valve ~ 25% Mitral Valve ~ 20% Pulmonary Valve 1 - 1.5% Mixed Rt. And Lt. Side 5 - 6%

IE in IV Drug Abusers Skin most predominant source of infection Also contamination of drugs and paraphernalia 70 - 100% of Rt. sided IE results in pneumonia and septic emboli Microbiology Staph aureus ~60% Streptococci and Enterococci ~20% Gram -ve bacilli ~10% Fungi (Candida and Aspergillus ~5%

IE in adults with congenital heart disease Common defects VSD PDA Bicuspid AV PS Coarctation of Aorta Occurs in defects with --mild or no hemodynamic consequences --high gradients --high velocity jets impinging on endocardium

Microbiology very important since virulence of the infecting organism is a significant factor in determining the success rates of both medical and surgical treatment

Pathogenesis Requires interaction between › Host vascular endothelium › Host haemostatic response › Adventitiously circulating organisms

Pathogenesis of Vegetations

Hemodynamic factors predisposing to Infective Endocarditis High velocity abnormal jet stream Flow from high to low pressure chamber Narrow orifice between two chambers creating pressure gradient

Pathology

Common sites of origin of extravalvular spread

Pathology Initially affects Valve leaflets in native valve endocarditis Can extend into annulus Annulus in prosthetic valve endocarditis Due to presence of sewing rim

Pathology - Embolic Phenomena Incidence Clinically 15 - 45% Pathologically 45 - 65% More with large mobile vegetations Fungi (Candida and Aspergillus) Group B and G Streptococci Staph aureus Result in Infarcts Abscesses Mycotic aneurysms

Pathology Immune Complex Associated Glomerulonephritis Arthritis Osler’s nodes

Clinical Features Onset usually within 2 weeks of infection › Indolent course - Malaise - Fatigue - Night sweats - Anorexia - Weight loss › Explosive course - CCF - S/o severe systemic sepsis

Clinical features › Fever - Usually < 39 °C, remittent › Murmurs - May be absent in - elderly - severe debility - CCF - Already on antibiotics › Murmurs - Appearance of new murmur or true change in existent murmur indicates infection with virulent organism

Other Clinical Features Splenomegaly ~ 30% Petechiae 20 - 40% Conjunctivae Buccal mucosa palate skin in supraclavicular regions Osler’s Nodes 10 - 25% Splinter Haemorrhages 5 - 10% Roth Spots ~ 5% Musculoskeletal (arthritis)

Complications Congestive Cardiac Failure (Commonest complication) Valve Destruction Myocarditis Coronary artery embolism and MI Myocardial Abscesses Neurological Manifestations (1/3 cases) Major embolism to MCA territory ~25% Mycotic Aneurysms 2 - 10%

Complications Metastatic infections Rt. Sided vegetations Lung abscesses Pyothorax / Pyopneumothorax Lt. Sided vegetations Pyogenic Meningitis Splenic Abscesses Pyelonephritis Osteomyelitis Renal impairment d/t Glomerulonephritis

Diagnosis Blood Cultures Other Laboratory Parameters Positive in 95% cases Other Laboratory Parameters Anaemia Leucocytosis (WCC may be normal in indolent infection) Thrombocytopenia  ESR (may be absent in CCF and renal failure) Urine - Microscopic hematuria / proteinuria

Echocardiography Can demonstrate lesion / vegetation in 60 - 80% of cases Difficult in prosthetic valve endocarditis TOE better than TTE Can demonstrate Morphology of valve Annular abscesses Hemodynamics of the valves Serial observations can contribute to decision for surgery

Treatment Medical Surgical

Principles of Medical Management Sterilization of Vegetations with antibiotics - prolonged Slowly metabolising bacteria due to high density, hence  sensitivity - high dose Bacteria deep inside vegetations -bactericidal

Principles of Medical Management Acute onset, fulminant -Within two to three hours of clinical diagnosis. -Take cultures, but do not wait for results Timing of Therapy Subacute onset, or having received recent antibiotic -Within two to three days. -Can wait for culture reports

Principles of Medical Management Isolation of organisms very important Therapy before isolation of organism Native valve endocarditis and in IV drug abusers Directed against Staph aureus Prosthetic valve endocarditis Broad spectrum antibiotics directed against Staph aureus Staph epidermidis Gram –ve bacilli

Indications for Surgery Left sided native valve endocarditis Valvular disruption leading to severe insufficiency and CCF Extravalvar extension Embolization of vegetations Failure of medical management Positive blood culture and systemic signs of infection after “adequate” antibiotic therapy Resistant organisms such as MRSA, Fungi , Pseudomonas Echo detected vegetation > 1 cm ??

Indications for Surgery Right sided native valve endocarditis Indications differ because: - Consequences of valve disruption and emboli are less - Success with antibiotics seems to be better --Failure of medical treatment --CCF, with its complications Indications (elective) --Recurrent pulmonary emboli with complications --Extravalvar spread (rare)

Indications for surgery Prosthetic valve endocarditis Early infection almost always require surgery Late infection Antibiotic therapy succeeds more often with Bioprosthesis compared to mechanical valves CCF due to prosthesis dysfunction Indications Multiple emboli Persistent infection

Indications for Surgery Special situations AIDS Not usually indicated since life expectancy due to AIDS very poor HIV +ve patient without AIDS IV Drug Abusers No change in indications since enough number survive > 10 years

As soon as there is a major indication When to operate ? As soon as there is a major indication Valid reasons for delay Acute CNS injury --Hemorrhagic infarct (Wait for 10 days to allow healing) --Coma (very poor prognosis ) Renal failure due to Glom’nephritis Follow through the acute phase (Prerenal failure -- early operation)

Principles of operation Repair or Replacement ? (More important with mitral valves) Repair contemplated only if: --Infection well controlled --Repair structurally feasible after involved tissue excised

Principles of operation Early operation once indicated Preop. knowledge of morphology of valve Good exposure (may be difficult in mitrals) Excision and debridement of all infected or involved tissue even if extensive reconstruction or permanent pacing required

Principles of operation Look for extravalvar extension If present, evacuate abscess cavity and repair with biological material such as autologous or bovine pericardium Suture valve onto clean and relatively strong tissue Temporary pacing leads

Which Prosthesis? Stented Bioprosthesis Mechanical Stentless Bioprosthesis Homograft

Important factor is location of infection Choice of prosthesis Important factor is location of infection -- Infection of cusps only: Choice does not matter, since all infected tissue is usually excised -- Perivalvar extension: No choice between mechanical and stented bioprosthesis (both with cloth sewing rims) Homograft, maybe stentless bioprosthesis have lesser incidence of infection

Choice of prosthesis Mechanical v/s Bioprosthetic No difference in linearized rates for recurrent or residual infection (~1-2% per patient year) No difference in operative mortality and complication free survival Infected bioprosthesis more easily sterilized (since infection initially involves leaflets) However, infection in bioprosthesis may hasten SVD due to damage to leaflets

Choice of prosthesis Homograft v/s others Hazard function for recurrent endocarditis has only low constant phase and has no high early hazard phase like other prosthesis Homograft best choice if valved conduit is required for root replacement ( > 50% annular dehiscence or aortoventricular discontinuity)

Postoperative Antibiotics To continue for 6 weeks if › Operated for --Acute fulminant infection --Failure of medical therapy --Resistant organisms › Excised valve yields positive cultures › Periannular involvement › Valve culture –ve, but organisms seen on histology › Positive blood cultures 3 – 4 days postop.

Results of Treatment Native valve endocarditis Medical Management Mortality 10 – 60 % Risk Factors Virulent organisms s/a MRSA, G-ve bacilli, fungi CCF Persistence of systemic sepsis Major septic embolus Extravalvar extension Acute renal failure

Results of Treatment Native valve endocarditis Surgical Management Hospital Mortality 5 – 20% Risk factors Virulent organisms Perivalvar extension Intractable CCF Renal and multiorgan failure

Results of Treatment Native valve endocarditis Surgical Management Recurrent Endocarditis ~ 2% Most occurs within 2 months post op. Same organism No fresh source of infection Perivalvar leaks 3-7%

Results of Treatment Prosthetic valve endocarditis Medical Management Mortality ~ 70% Risk factors Valve incompetence or perivalvar leak Early postoperative onset Virulent organism

Results of Treatment Prosthetic valve endocarditis Surgical Management Hospital Mortality 0 –22% Risk factors Early postoperative infection Virulent organism Perivalvar extension Delay in operation

Results of Treatment Prosthetic valve endocarditis Surgical Management Long term results differ from valve replacement for NVE or other lesions Have comparatively unfavourable rates of late death, recurrence of infection and reoperation

Antibiotic Prophylaxis Protocol usually followed recommended by Dajani et al in JAMA 1990 Recommended in following conditions Prosthetic valves Previous history of infective endocarditis (even without underlying heart disease) Most congenital heart diseases Rheumatic or other acquired valve disease IHSS MVP with MR

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