Infective Endocarditis

Question 1

Infective Endocarditis RFs

Answer 1

• Cardiac conditions
• Valvular heart disease (usually internal structure resistant to attachment, damage leaves tissue susceptible)
• Valve replacement
• Structural congenital heart disease, including corrected
• PHx
• HOCM

Question 2

Infective Endocarditis Pathogenesis

Answer 2

• All cases start with non-bacterial thrombosis
• Deposition of thrombus on low pressure side (Venturi effect)
• Can be acute, subacute or non-bacterial
• Non-bacterial from CKD, SLE

Question 3

Infective Endocarditis Affected Valves

Answer 3

In decreasing order of frequency

• Mitral
• Aortic
• Combined M+A
• Tricuspid
• Pulmonary (rare)

Question 4

Infective Endocarditis Organisms

Answer 4

Staphylococcus aureus

• Most common cause acute and subacute
• Most common with prosthetic valves and IV drug abuse
• High mortality rate

Streptococci

• S. viridans
• Group D usually subacute 3rd most common
• Strep intermedies
• Group A, C G, B

Pseudomonas
-Usually acute IE

HACEK
-5%

Fungi and enterococci

Question 5

Infective Endocarditis Presentation

Answer 5

• Very variable
• High index of suspicion
• May present acute
• May present subacute with nonspecific symptoms e.g. fatigue, low-grade fever, flu-like illness, polymyalgia like symptoms, loss of appetite, back pain
• Most present with fever, poor appetite, weight loss
• Heart murmurs in 85%
• Splinter haemorrhages
• Consider in all patients with stroke or TIA and fever

Question 6

Infective Endocarditis Examination

Answer 6

• Fever
• Heart murmurs
• Petechiae (conjunctiva, hands and feet, chest and abdominal wall, oral mucosae and soft palate)
• Splinter haemorrhages, osler’s nodes, Roth’s spots (retinal haemorrhage with pale centre), Janeway lesions
• Arthritis
• Splenomegaly
• Can cause meningism

Question 7

Infective Endocarditis Criteria for Investigation for IE

Answer 7

• Febrile illness and murmur of new valvular regurgitation (stenosis is rare)
• Febrile illness with risk factor
• New unexplained embolic event
• Unexplained blood cultures

Question 8

Infective Endocarditis Differentials

Answer 8

• SLE
• Cardiac tumours
• Lyme disease
• Presentations that can cause difficulty with diagnosis
• Meningitis, hemiplegia from emboli, renal infarcts causing painless haematuria, splenic infarction…

Question 9

Infective Endocarditis Ix

Answer 9

• CXR
• ECG (10% will develop conduction deficits)
• Blood cultures, must be continuous and from different sites as bacteria is not always picked up
• Echo as soon as possible
• If blood culture-negative IE, serological testing for Coxiella and Bartonella species should be performed

Question 10

Infective Endocarditis Diagnostic Criteria

Answer 10

Duke’s criteria, two major and three minor or five minor needed for definitive diagnosis

• Major is positive blood culture (typical organism from two separate cultures) or evidence endocardial involvement (on echo)
• Minor is other factors: predisposition, fever, vascular phenomena, immunological phenomena…

Question 11

Infective Endocarditis Management

Answer 11

• Antibiotics (very long list)
• Seek surgical opinion at earliest opportunity for those with prosthetic material
• If valve causing circulatory problems, seek surgical opinion

Question 12

Infective Endocarditis Complications

Answer 12

• MI, pericarditis, cardiac arrhythmias
• Heart valve insufficiency
• Heart failure…

Question 13

Infective Endocarditis Prognosis

Answer 13

Still quite poor, 30% 1 year mortality