Cardiology: TR & Infective Endocarditis Flashcards
Define what is meant by infective endocarditis
Infection of the endocardial surface of the heart, particularly implicating the heart valves or an intracardiac device
What are the three major types or categories of IE? [3]
Native valve endocarditis (NVE):
- normal valves without previous intervention
- May be acute or subacute.
Prosthetic valve endocarditis (PVE):
- may occur early (< 1 year) or late (> 1 year) following surgical intervention.
- Account for 10-20% of cases.
Intravenous drug abuse (IVDA) endocarditis:
- classically affects the tricuspid valve (50%). Staphylococcus aureus most common microorganism.
Which valve is most commonly effected by IVDA endocarditis? [1]
Tricuspid valve
TOM TIP: In exams, classically infective endocarditis occurs after what type of procedure? [1]
Classically, a dental procedure is associated with a brief bacteraemia that our immune system is able to control.
Describe the pathophysiology of IE [6]
IE is characterised by the formation of vegetations on cardiac valves.
IE occurs when bacteria enter the bloodstream and deposit onto the endocardial surface of the heart.
Once deposited on the endocardial surface, the organisms adhere and eventually lead to invasion and destruction of the valve leaflets. The key pathological process in IE is formation of infected vegetations.
On the endocardial surface, a small nidus of adherent platelet-fibrin complex becomes infected by deposited bacteria.
This complex forms a vegetation, which is essentially a collection of fibrin, platelets, white blood cells, red blood cell debris and clusters of bacteria.
The vegetation may increase in size and damage the endocardial tissue including valves.
The vegetation can cause local destruction of valves, which leads to regurgitant murmurs and eventually congestive cardiac failure
Which of the following is most commonly effected by IE?
Mitral
Aortic
Combined mitral and aortic
Tricuspid
Pulmonary
Mitral - most common
Aortic
Combined mitral and aortic
Tricuspid
Pulmonary - least common
Describe the different presentations of IE [3]
Acute
Subacute
Chronic
What are the risk factors for IE?
- Intravenous drug use
- Structural heart pathology
- Chronic kidney disease (particularly on dialysis)
- Immunocompromised (e.g., cancer, HIV or immunosuppressive medications)
- History of infective endocarditis
Which structural pathologies increase the likelihood of IE? [5]
- Valvular heart disease
- Congenital heart disease
- Hypertrophic cardiomyopathy
- Prosthetic heart valves
- Implantable cardiac devices (e.g., pacemakers)
What is the most common infective agent causing IE? [1]
Staphylococcal aureus
Asides from Streptococcus aureus, name a common cause of IE [1]
Enterococcus faecalis
Describe the symptoms of IE [7]
- Fever (90%)
- Malaise, lethargy
- Anorexia
- Weight loss
- Abdominal pain: splenic abscess
- Haematuria: renal embolic phenomenon
- Cardiac symptoms: shortness of breath, chest pain, palpitations
Name this sign of IE [1]
Is it tender or non-tender? [1]
Is it more likely in acute or subacute?
Oslers Nodes
Tender
Subacute > acute.
Name and describe this sign of IE [1]
Is it more likely in acute or subacute?
Roth spots: exudative, oedematous hemorrhagic lesions of the retina with pale centre (immune complex deposition)
Subacute > acute.
Name and describe this sign [1]
Is it tender? [1]
Is it found in subacute or acute? [1]
Janeway lesions:
- Acute > subacute.
- Tender
Name this sign of IE [1]
Conjunctival petechiae in infective endocarditis
Describe the cardiac murmurs found in IE [2]
Cardiac murmur (85%): pansystolic murmur of mitral regurgitation
or
early diastolic murmur of aortic regurgitation
What would you expect to hear upon ascultating someone with IE? [2]
Murmur
Bibasal crackles
Around 25% of patients with IE have evidence of [] at the time of diagnosis.
Around 25% of patients with IE have evidence of embolic phenomenon at the time of diagnosis.
Peripheral stigmata of IE are increasingly less common due to earlier recognition and diagnosis.
What neurological emboli can IE cause? [4]
cerebral abscess
intracerebral haemorrhage
embolic stroke
seizures
Describe the investigations used to investigate IE
Blood cultures BEFORE Abx:
- Three blood culture samples are recommended, usually separated by at least 6 hours and taken from different sites.
Transoesophageal echocardiography (TOE)
- Vegetations (an abnormal mass or collection) may be seen on the valves
Special imaging investigations may be used in patients with prosthetic heart valves:
- 18F-FDG PET/CT
- SPECT-CT
Why might you perform thorax and abdominal imaging for IE patients? [2]
Thorax and abdominal imaging: CT or US may be needed to look for pulmonary or splenic abscesses
What is the name for the criteria used for IE? [1]
Describe how a diagnosis is made from Dukes criteria [1]
Modified Duke criteria
A diagnosis requires either:
* One major plus three minor criteria
* Five minor criteria
What are the major criteria in Dukes classification of IE? [2]
What are the minor criteria in Dukes classification of IE? [5]
Major criteria:
* Persistently positive blood cultures (typical bacteria on multiple cultures)
* Specific imaging findings (e.g., a vegetation seen on the echocardiogram)
Minor criteria are:
* Predisposition (e.g., IV drug use or heart valve pathology)
* Fever above 38°C
* Vascular phenomena (e.g., splenic infarction, intracranial haemorrhage and Janeway lesions)
* Immunological phenomena (e.g., Osler’s nodes, Roth spots and glomerulonephritis)
* Microbiological phenomena (e.g., positive cultures not qualifying as a major criterion)
