Infective Endocarditis

Question 1

What is infective endocarditis?

Answer 1

Inflammation of the inner tissues of the heart (endocardium), often the valves, caused by an infective cause

Question 2

What factors put patients at risk of developing infective endocarditis?

Answer 2

i.v. drug use
indwelling cardiac devices
valvular disease/replacement
structural heart disease
previous IE
hypertrophic cardiomyopathy
invasive vascular procedures

Question 3

What is the classical presentation of infective endocarditis?

Answer 3

Acute febrile illness w/ new murmur

CAN BE INSIDIOUS (malaise, anorexia, lethargy, arthralgia)

Question 4

What are the common causative organisms of infective endocarditis?

Answer 4

Strep viridans
Staph aureus
Strep epidermis
Pseudomonas aeruginosa
Fungi (subacute)
Enterococci
HACEK organisms

Question 5

What are the HACEK organisms?

Answer 5

Gram -ve bacteria causing endocarditis
Haemophilius
Actinobacillus
Cardiobacterium
Eikenella
Kingella

Question 6

What morphological changes are seen on affected heart valves?

Answer 6

Formation of infective lesions along edges of heart valves (vegetations)
Ulceration results in erosion/perforation of valve cusps
Causes valvular incompetence

Question 7

Describe acute infective endocarditis

Answer 7

Mostly occurs on normal valves
Acute heart failure and emboli
S. aureus
Mortality 5-50%

Question 8

Describe subacute infective endocarditis

Answer 8

Mostly occurs on abnormal valves
Insidious onset
Caused by normal GI/skin commensals
Similar mortality

Question 9

What valves are most commonly affected by IE?

Answer 9

Mitral
Aortic
-combined mitral/aortic
Tricuspid
Pulmonary (v. rare)

Question 10

What are the complications of infective endocarditis?

Answer 10

Valve destruction - heart failure
Embolic disease
Glomerulonephritis

Question 11

Describe valve destruction leading to heart failure

Answer 11

Damage to heart valves due to infective lesions/ulceration

Regurgitation/blockage leads to build up of pressure - heart failure

Question 12

Describe embolic disease

Answer 12

Septic embolus - infection of one part of the body that migrates to the other
Causes any problems associated with emboli AND causes infection
Causes abscesses in organs

Question 13

Describe Glomerulonephritis

Answer 13

Inflammation within the glomerulus caused by immune complex deposition
-decreased blood flow
-loss of filtration
Causes nephrotic/nephritic syndrome

Question 14

What investigations should be performed when infective endocarditis is suspected?

Answer 14

Blood cultures - 3 sets, different times, peak of fever (90% +ve)
Echocardiography - visualisation of valves/lesions
FBC - anaemias, WCC
ESR/CRP - sign of infection/inflammation
U&E - renal damage?
Renal function tests - urinalysis, eGFR, creatinine

Question 15

What is Duke’s criteria?

Answer 15

Measure of major/minor criteria suggesting IE

-2 major OR 1 major + 3 minor

Question 16

What is the general management for infective endocarditis?

Answer 16

i.v. antibiotics
-empiric therapy while awaiting cultures
-targeted therapy if organism known
Surgery when indicated

Question 17

What are the indications for surgery?

Answer 17

IE affecting prosthetic material
Heart failure (A/M w/ refractory pulmonary oedema, poor haemodynamic tolerance)
Uncontrolled infection (abscess, blood culture)
Aiming to prevent embolism (A/M w/ large vegetations)

Question 18

What antibiotics are commonly used to treat infective endocarditis?

Answer 18

Varies dependent on likely cause/affected valve
Cover gram-ve/gram+ve
Give i.v.

Question 19

What features may be found on examination of a patient w/ infective endocarditis?

Answer 19

Fever + new murmur
Microscopic Haematuria (70%)
Splenomegaly (40%)
Osler's Nodes (15%)
Clubbing (10%)
Splinter Haemorrhages (10%)
Roth Spots (5%)
Janeway Lesions
Petechial Rash
Digital Infarcts

Question 20

What are Osler’s Nodes?

Answer 20

Tender, red nodules in the finger due to immune complex deposition

Question 21

What are Roth Spots?

Answer 21

Pale areas w/ surrounding haemorrhage on retina

Question 22

What are Janeway Lesions?

Answer 22

Painless palmar/plantar macules

Question 23

What are the Duke Major criteria?

Answer 23

+ve culture

Endocardial involvement on echo

Question 24

What are the Duke Minor criteria?

Answer 24

Predisposition
Fever >38
Vascular/immunological signs
Culture/echo positivity not sufficient for major criteria

Question 25

What is the common antibiotic regiment used to treat endocarditis?

Answer 25

Benzylpenicillin
Gentamicin
Flucloxacillin
IV, 4 weeks