INFECTIVE ENDOCARDITIS

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INFECTIVE ENDOCARDITIS

• Manoj Kuduvalli

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Definition

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

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ORIGINAL CLASSIFICATION(Prior to Antibiotic era)
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Current Criteria for Classification

• Underlying Anatomy
• Native Valve Endocarditis
• Prosthetic Valve Endocarditis
• Infecting Organism
• Serves as basis for therapy and
  prognosis

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Native Valve EndocarditisUnderlying 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

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Native Valve EndocarditisMicrobiology

• Streptococci 50 - 70
• Viridans Streptococci (50 of all Strep)
• Staphylococci 25
• Mostly Coagulase ve Staph. Aureus
• Staph. Epidermidis
• Enterococci 10

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Native Valve EndocarditisMicrobiology

• 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

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Native Valve EndocarditisMicrobiology

• 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 PenicllinGentamicin
• Resistant strains prevalent

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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

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Prosthetic Valve EndocarditisClassification

• Early ( lt 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 ( gt 60 days)
• After endothelialization
• Incidence 0.2 -0.5 / pt. year
• Transient bacteraemia from dental, GI or GU
• Microbiology
• resembles native valve endocarditis

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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

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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

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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

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

• Requires interaction between
• Host vascular endothelium
• Host haemostatic response
• Adventitiously circulating organisms

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Pathogenesis of Vegetations
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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

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

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Pathology Immune Complex Associated

• Glomerulonephritis
• Arthritis
• Oslers nodes

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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

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Clinical features

• Fever
• - Usually lt 39 C, remittent
• - 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

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Other Clinical Features

• Splenomegaly 30
• Petechiae 20 - 40
• Conjunctivae
• Buccal mucosa
• palate
• skin in supraclavicular regions
• Oslers Nodes 10 - 25
• Splinter Haemorrhages 5 - 10
• Roth Spots 5
• Musculoskeletal (arthritis)

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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

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Complications

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

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Diagnosis

• Blood Cultures
• 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

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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

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Treatment
Medical
Surgical
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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

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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

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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

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Indications for SurgeryLeft 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 gt 1 cm ??

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Indications for SurgeryRight 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
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  with complications
• --Extravalvar spread (rare)

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Indications for surgeryProsthetic 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

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Indications for SurgerySpecial 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 gt 10 years

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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 Glomnephritis
• Follow through the acute phase
• (Prerenal failure -- early operation)

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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

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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

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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

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Stented Bioprosthesis
Mechanical
Which Prosthesis?
Stentless Bioprosthesis
Homograft
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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

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Choice of prosthesisMechanical 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

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Choice of prosthesisHomograft 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 ( gt 50 annular
  dehiscence or aortoventricular discontinuity)

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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.

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Results of TreatmentNative valve
endocarditisMedical 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

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Results of TreatmentNative valve
endocarditisSurgical Management

• Hospital Mortality 5 20
• Risk factors
• Virulent organisms
• Perivalvar extension
• Intractable CCF
• Renal and multiorgan failure

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Results of TreatmentNative valve
endocarditisSurgical Management

• Recurrent Endocarditis 2
• Most occurs within 2 months post op.
• Same organism
• No fresh source of infection
• Perivalvar leaks 3-7

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Results of TreatmentProsthetic valve
endocarditisMedical Management

• Mortality 70
• Risk factors
• Valve incompetence or perivalvar leak
• Early postoperative onset
• Virulent organism

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Results of TreatmentProsthetic valve
endocarditisSurgical Management

• Hospital Mortality 0 22
• Risk factors
• Early postoperative infection
• Virulent organism
• Perivalvar extension
• Delay in operation

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Results of TreatmentProsthetic valve
endocarditisSurgical 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

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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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Thank you!