Infective endocarditis

Question 1

Definition of Infective endocarditis (IE)

Answer 1

Endocarditis - infection involving the endocardial surface
Valvular structures- native and prosthetic valves
Chordae tendineae
Sites of septal defects
Mural endocardium – the posterior wall of the left atrium becomes rough and wrinkled
IE is a deadly disease associated with high mortality (15-30% in-hospital) and severe complication.
Mortality and prognosis remains unchanged for over 30 years
Despite advancement in management /diagnostics

Question 2

Infective endocarditis incidence

Answer 2

IE is a rare disease with low incidence
Incidence :3-10 cases /100,000 people per year
14.5 episodes /100,000 people are 70-80yrs old
Male : Female ratio ≥2.1
Worse prognosis in female

Question 3

IE incidence in the past

Answer 3

Young adults with previously well-identified valve disease

Chronic /subacute course (delayed diagnosis)

Question 4

IE incidence now

Answer 4

Older patients with degenerative heart disease ( Aortic Stenosis)
Healthcare –associated procedures
Intra cardiac devices (ICD)
Valve disease( Mitral valve prolapse, Bicuspid aortic valve)/Congenital heart disease
Prosthetic valve
IVDU
Immunocompromised patients

Question 5

Risk factors for native valve IE

Answer 5

Mitral valve disease
Rheumatic heart disease
Congenital heart disease
Degenerative  heart disease
Asymmetrical septal hypertrophy
Intravenous Drug abusers
Alcoholic cirrhosis
Diabetic mellitus
Indwelling medical devices

Question 6

Mitral valve prolapse

Answer 6

high prevalence 2-4%
20% are young female
relative risk of 3.5-8.2 for endocarditis

Question 7

Congenital heart disease and endocarditis

Answer 7

10-20% of endocarditis cases in young adults
8% of cases of endocarditis in older adults
can be ventricular septal defect, bicuspid aortic valve, patent ductus arterious

Question 8

Pathophysiology of how endocarditis starts

Answer 8

normal valve endocardium is resistant to colonisation and infection.

then mechanical endothelial disruption exposes ECM protein which promotes production of tissue factors.

this causes deposition of fibrin and platelets and causes non bacterial thrombotic endocarditis (NBTE)

NBTE facilitates bacterial adherence and infection

Question 9

Pathophysiology for damaged endothelial valve

Answer 9

turbulent blood flow (Venturi effect)
Electrodes
catheters
inflammation (rheumatic carditis)
degenerative valve disease

Question 10

Pathophysiology for normal valve endothelial Inflammation

Answer 10

Endothelial inflammation
expression of integrins from these cells (transmembrane proteins that bind circulating fibronectin to the endothelial surface.
staph. aureus and other pathogens carry fibronectin and so bind proteins on their surface
adherent organisms trigger active internalization into valve endothelial cells

Question 11

Pathophysiology: Bacteraemia

Answer 11

Invasive procedure
Dental procedures requiring manipulation( gingival /periapical region
Dental procedures -perforation of oral mucosa
GU and GI surgery
Intravascular catheters
Extra-cardiac infections
Non-invasive activities (chewing and tooth brushing)-low grade bacteraemia of short duration but with high incidence.

Question 12

Aetiology- causative organisms

Answer 12

Viridans group streptococci
Staphylococcus aureus
 Enterococci 
Coagulase-negative staphylococci				
 Haemophils  parainfluenzae
 Actinobacillus 
Streptococcus bovis
Fungi
Coxiella burnetii, 
Brucella species, 
Culture-negative Haemphilus species, Actinobacillus,actinomycetemcomitans, Cardiobacterium hominis, eikenella corrodens and Kingella species (HACEK)

Question 13

Classification of Infective Endocarditis

Answer 13

Acute(days/weeks) or subacute(weeks to months)
Nidus(localization) of infection± intra-cardaic material
Mode of acquisition (IVDU, Healthcare or community)
Active Infective endocarditis
Recurrence (relapse or reinfection)

Question 14

Diagnosis of Infective Endocarditis

Answer 14

Bacteraemia with audible murmur should raise suspicion
could be in elderly or immunocompromised patients
acutely- fever, embolic signs, decompensated HF

subacute- fever, nonspecific constitutional symptoms or palpitation and immunologic/vascular phenomena

Question 15

Common symptoms

Answer 15

fever/chills
night sweats, malaise, fatigue, anorexia, weight loss
weakness
arthralgia (joint pain)
headache
SOB

Question 16

Clinical signs of IE

Answer 16

regurgitant murmur with signs of HF
janeway lesions (Haemorrhagic ,macular, painless plaques with predilection for palms and soles.)

Osler nodes (Small ,painful nodular lesion found on pads of fingers or toes)

Roth spots (Retinal haemorrhage with a white or pale centre)

meningeal signs

splinter haemorrhage

cutaneous infarcts

Petechial haemorrhage (on back of mouth)

vasculitic rash

Question 17

Investigation of IE

Answer 17

Blood culture- Timing. 3 sets and sites 30mins apart. +/- cultures
FBC.ESR/CRP- elevated acute inflammatory makers
U+Es- renal failure
Urinalysis- +ve for blood
ECG: PR interval prolongation ≥200ms
CXR: Pulmonary congestion or abscess.
Further Imaging for subgroups – MSCT(multislice coronary angiogram, shows perivalvular abscesses better than ECHO),MRI,18F-FDG -PET/CT and Leucocyte SPECT/CT –detect silent vascular phenomena/ endocardial lesions
Echocardiography ( transthoracic (TTE) ± transesophageal (TOE)

Question 18

ESC 2015 Modified Duke’s Criteria-Major criteria

Answer 18

1. Blood cultures positive for IE
   Typical microorganisms consistent with IE from 2 separate blood cultures:
   Viridans streptococci, Streptococcus gallolyticus (Streptococcus bovis), HACEK group,
   Staphylococcus aureus; OR
   Community-acquired enterococci, in the absence of a primary focus;
   OR

Microorganisms consistent with IE from persistently positive blood cultures:
≥2 positive blood cultures of blood samples drawn >12 h apart; OR
All of 3 or a majority of ≥4 separate cultures of blood (with first and last samples drawn ≥1 h apart);
OR

C. Single positive blood culture for Coxiella burnetii or phase I IgG antibody titre >1:800

2. Imaging positive for IE
   A. Echocardiogram positive for IE:
   • Vegetation
   • Abscess, pseudoaneurysm, intracardiac fistula
   •Valvular perforation or aneurysm
   • New partial dehiscence of prosthetic valve
   B. Abnormal activity around the site of prosthetic valve implantation detected by 18F-FDG PET/CT (only if the prosthesis was implanted for >3 months) or radiolabelled leukocytes SPECT/CT.

C. Definite paravalvular lesions by cardiac CT.

Question 19

ESC 2015 Modified Duke’s Criteria-Minor criteria

Answer 19

Predisposition such as heart condition or injection drug use

fever over 38C

vascular phenomena such as major arterial emboli, septic pulmonary infarcts, infectious aneurysm, intracranial haemorrhage, conjunctival haemorrhages, janeways lesions

immunological phenomena such as glomerulonephritis, oslers nodes, roths spots, rheumatoid fever

microbiological evidence such as positive blood culture but doesn’t meet a major criteria or serological evidence of active infection with organism consistent with IE

Question 20

Modified Duke Criteria

Answer 20

Diagnosis of Definite IE : 2 major criteria
or 1 1 major criterion + 3 minor criteria or 5 minor criteria

Diagnosis of Possible IE : 1 major criterion + 1 minor criterion OR
3 minor criteria

IE Rejection criteria : Resolution of endocarditis syndrome with antibiotics therapy for ≤ 4 days

Question 21

Empirical treatment of IE

Answer 21

3 sets of blood culture 30mins apart THEN IV antibiotics (amoxicillin+flucoxacillin+gentamicin or gentamicin+vancomycin if allergic)

consider previous surgery and antibiotics and place of infection for local epidemiology

Question 22

Predictors of poor outcome

Answer 22

old age
prosthetic valve IE
diabetes mellitus
comorbidity
HF
RF
IS
brain haemorrhage
septic shock
staph. aureus
fungi
non HACEK gram negative bacilli
periannular complications
severe left sided valve regurgitation
low left ventricular ejection fraction
PHT
large vegetations
severe prosthetic valve dysfunction
premature mitral valve closure

Question 23

Complications and indications for surgery

Answer 23

Heart failure in IE: valvular regurgitation- leaflet perforation etc
42-60% of Native Valve Endocarditis(NVE)
Aortic IE> Mitral IE

Uncontrolled Infection: Perivalvular abscess
More common in Aortic IE (10-40%) in NVE
56-100% of Prosthetic valve endocarditis(PVE) Mortality rate 41%

Prevention of systemic embolism: migration of cardiac vegetation to brain/spleen from left-IE Size and mobility of vegetation .
Pulmonary embolism are the results of right sided IE.

Question 24

Principles of prevention of IE

Answer 24

1.The principles of antibiotic prophylaxis when performing procedures at risk of IE in patients with predisposing cardiac conditions is maintained.
2. Antibiotic prophylaxis must be limited to patients with the highest risk of IE undergoing the highest risk dental procedures. (dental procedures requiring manipulation of the gingival or periapical region of the teeth or perforation of the oral mucosa)
Patients with a prosthetic valve, including transcatheter valve, or a prosthetic material used for
cardiac valve repair.
Patients with previous IE.
Patients with congenital heart disease:
- any cyanotic congenital heart disease. - congenital heart disease repaired with prosthetic material whether placed surgically or by
percutaneous techniques, up to 6 months after the procedure or lifelong if there remains residual shunt or valvular regurgitation.
3. Good oral hygiene and regular dental review are more important than antibiotic prophylaxis to reduce the risk of IE.
4.Aseptic measures are mandatory during venous catheter manipulation and during any invasive procedures in order to reduce the rate of health care-associated IE.

basically use abx right, wash hands, disinfect wounds, good hygiene, no piercings or tattoos, limit infusion catheters etc