The cardiovascular system - Coronary artery disease 2 Flashcards
What is infective endocarditis (IE)?
Refers to any infection of the endocardial surface of the heart
Describe the epidemiology of infective endocarditis
- Men are predominately affected
- In the developed world, IE is mostly a disease seen in elderly patients and commonly occurred in patients with pre-existing valvular disease from rheumatic heart disease
Causes of endocarditis can be divided into 5. Give the 5 causes
- Native valve endocarditis
- Prosthetic valve endocarditis (PVE)
- IV drug users (IVDU)
- Culture-negative IE
- Non-infective endocarditis
a) What is native valve endocarditis (NVE) commonly due to?
b) What is the most common organisms causing NVE?
a) Rheumatic heart disease, congenital heart disease or structural disease
b) Usually due to streptococcal species and presents with a subacute course
- Streptococcal species (alpha-haemolytic, S.bovis) and enterococci: implicated in around 70% of cases
- Staphylococcal species: implicated in around 25% of cases. More aggressive disease
a) What does the prosthetic valve endocarditis (PVE) depend on?
b) What is the most common organisms causing early and late PVE?
a) Aetiology of PVE depends on it occurs early (<1 year) or late (>1 year)
b) Coagulase-negative staphylococcus (CoNS) account for 30% of PVE
- Early PVE: occurring shortly after surgery. Staphylococcal species commonly implicates. Acute course (that can cause local abscess, fistula formation, and valvular dehiscence)
- Late PVE: occurring a medium-to-long period after surgery. Streptococcal species commonly implicates. Has a more subacute course
a) What organism is most commonly implicated in IV drugs users (IVDU) associated IE?
b) Explain which valve is most commonly affected?
a) Staphylococcus aureus
b) The tricuspid valve (together with the mitral valve) is commonly affected in IVDU.
Blood from the venous circulation encounters the tricuspid valve first, so bacterial load from repeated injections with contaminated drug paraphernalia is more likely to result in right-sided endocarditis
a) What is culture-negative infective endocarditis defined as?
b) What are 4 possible causes of culture negative IE may be due to?
a) Defined as endocarditis with no definite microbiological aetiology despite adequate sampling
b)
- Typical pathogens
- Pathogens with complex growth
- Intracellular bacteria
- Non-bacterial pathogens (e.g., fungi)
What are 4 possible causes of non-infective endocardiitis
- Physical trauma caused by IV catheters or placing wires
- Systemic lupus erythematosus (SLE)
- Metastatic lung, GI, and pancreatic cancers
- Chronic infections e.g., tuberculosis, osteomyelitis
What are the 3 most common organism species causing IE?
Staphylococcal, streptococcal and enterococcal
Staphylococcal species is one of the most common cause of IE
a) What specific staphylococcal species is most common?
b) What is another common species and what is it commonly associated with?
a) Staphylococcus aureus
b) Coagulase negative staphylococcus (CoNS) and commonly associated with prosthetic devices
Streptococcal species is one of the most common cause of IE.
Give the two most common streptococcal species
Alpha-haemolytic streptococci e.g., Strep Viridans
Beta-haemolytic streptococci e.g., Strep. Bovis
Strep.bovis is a beta-haemolytic streptococci that can cause IE
a) What type of people is this organism commonly seen in?
b) What conditions is the organism associated with and what investigation is required?
a) Elderly
b) Adenomas/adenocarcinomas of the colon and IBD. Colonoscopy is indicated
Enterococcal species is one of the most common cause of IE.
a) What is the most common organism of enterococcus species causing IE?
b) What % of all enterococcus species is caused by this organism?
a) Enteroccous facecialis
b) 90%
S.epidermis is a common organism that causes IE. What type of IE does it cause?
Causes early prosthetic valve IE
Aside from staphylococcus, streptococcal and enterococcus species. What other organisms can cause IE?
- Q fever - Coxiella burnetii
- Brucella
- Pseudomonas aerugionsa
- Fungal - Candida e.g., C.albicans, C.stellatoidea
- HACEK: Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella –> fastidious (hard to culture) group of gram-negative staining bacteria
When should you suspect Q fever (Coxiella burnetii) causing IE?
Suspect if contact with farm animals and cats/dogs
When should you suspect Brucella causing IE?
Suspect if recent travel or at risk occupation e.g., farmers
75% of fungal infections are caused by the Candida (e.g., C.albicans, C. stellatoidea) . These can cause IE.
What type of people are particularly affected?
IVDU and immunocompromised
Name the two main disease processes underpinning infective endocarditis
- Endocardial injury
- Baceraemia
a) Describe patient-associated risk factors of IE
b) Describe cardiac risk factors of IE
c) Aside from patient-associated and cardiac risk factors of IE. What are other risk factors of IE?
a)
- Age - occurs in patients aged > 60 years
- Male predominance - sex dominance varies from 3:2 to 9:21
- IVDU
- Dentition - poor dental hygiene, dental infections and certain procedures increase risk
b)
- Structural heart disease (75% of IE patients have underlying structural heart disease)
- Valvular heart disease
- Congenital heart disease (e.g., bicuspid aortic valve, ventricular septal defect and cyanotic heart disease)
- Prosthetic heart valves
- Previous IE
- Intravascular devices
b)
- Immunosuppression (e.g., HIV)
- Haemodialysis
a) Describe the symptoms of IE
b) Describe the signs of IE
a)
- Pyrexia
- Constitutional symptoms: malaise, fatigue, anorexia, weight loss
- Abdominal pain: splenic abscess
- Haematuria: renal embolic phenomenon
- Cardiac symptoms: Dyspnoea, chest pain, palpitations
b)
Heart
- New or worsening murmur (85%) - pansystolic murmur of mitral regurgitation or early diastolic murmur of aortic regurgitation
Eyes
- Roth spots: exudative, oedematous haemorrhage lesions of the retina with place centre due to septic emboli to the retina
- Petechiae
Hands and feet
- Clubbing
- Splinter haemorrhages: thin, reddish-brown lines of blood under the nails (micro emboli)
- Osler’s nodes: tender subcutaneous violaceous nodules mostly on the pads of finger and toes. Subacute > acute
- Janeway lesions: contender erythematous macula’s on the palms and soles (micro abscesses). Acute > subacute
Skin and mucosa
- Petechiae on extremities and buccal mucosa
Splenomegaly
The mnemonic to describe clinical features of IE is FROM JANE. What does this stand for?
Fever
Roth spots
Osler nodes
Murmur
Janeway lesions
Anaemia
Nail-bed haemorrhages
Emboli
Around 25% of patients with IE have evidence of embolic phenomenon at the time of diagnosis.
Describe the embolic phenomenons that can manifest
Hands and feet: Osler nodes and janeway lesions
Eyes (2%): Roth spots
Neurological (40%)l: cerebral abscess, intracerebral haemorrhage, embolic stroke, seizures
Septic emboli: splenic, renal, pulmonary abscesses, vertebral osteomyelitis, septic arthritis, psoas abscess
Immune reaction (ie., immune complex deposition): glomerulonephritis, synovitis
Describe the differential diagnosis of infective endocarditis and what is the key differential to be excluded?
May mimic rheumatological and autoimmune condition such as RhA and SLE int he subacute or chronic state
Must be differentiated from other causes of sepsis including pneumonia and abdominal sepsis in the acute setting
Describe the 1st line, 2nd lien and 3rd line investigations for IE, including the possible findings
1st line (diagnostic)
- Blood culture (microbiology)
- Echocardiography
2nd line
- blood tests: raised WCC, ESR/CRP
- urine dipstick: microscopic haematuria
- ECG: 10% develop conduction problem; heart block (prolonged PR) may be a sign of aortic root abscess
3rd line
- Thorax and abdominal imaging with CT/MRI: to look for pulmonary or splenic abscesses
- Cerebral imaging with CT/MRI: assesses for neurological complications
Describe how the blood culture must be taken for a microbial diagnosis of IE
- At least three set of blood cultures should be obtained
- Blood cultures taken at 30 mine intervals
- At last 10ml each sample from different peripheral sites using immaculate aseptic technique
a) When should an echocardiography be performed in IE?
b) Describe the different echocardiograms you worked use and the indications for their use
c) What is the hall mark finding on echocardiogram?
d) Give four other possible findings
a) Should be performed rapidly in all with moderate to high suspicion of IE
b)
- A TTE is performed in the first instance (but has lower sensitivty with a specificity of 99%)
- A TOE is performed following a positive TTE to look for local complications (e.g., valve perforations, abscess formation). Has a sensuosity of 90-100% and should e performed in most patients
c) Valvulare vegetation (oscillating irregular mass)
d)
- Abscess formation
- Pseudoaneurysms
- Valve perforations
- New dehiscence of a prosthetic valve
The modified duke criteria. It contains both major and minor criteria that are used to make a diagnosis of IE. It has an 80% sensitivity and specificity.
a) Describe the major criteria
b) Describe the minor criteria
a)
- Microbiological criteria (positive blood culture)
Two or more separate blood cultures for typical IE microorganisms:
- Streptococci viridians
- Other streptococci,
- S.auerus
OR
Persistently positive blood cultures
- Blood cultures drawn more than 12 hrs apart
- Coxiella burnetii
- Evidence of endocardial involvement
- Oscillating intracardiac mass OR abscess OR
- New parietal dehiscence of prosthetic valve
OR
New valvular regurgitation
- A change in pre-existing murmur is insufficient
b)
Predisposing factors
- predisposing heart disease
- IVDU
Symptoms
- Fever > 38
Vascular phenomenon
- Major arterial emboli
- Pulmonary emboli
- Mycotic aneurysms
- intracranial haemorrhage
- Janeway lesions
Immunological phenomenon
- Glomerulonephritis
- Osler’s nodes
- Roth spots
- Rheumatoid factor
Microbiological evidence
- Positive culture not meeting major criteria
Based on the modified duke criteria. IE can be divided into definite, possible and rejected
a) What is needed for IE to be definite?
b) What is needed for IE to be possible ?
c) What is needed for IE to be rejected?
a) 2 major criteria OR 1 major and 3 minor criteria or 5 minor criteria
b) 1 major and 1 minor criteria OR 3 minor criteria
c) Firm alternative diagnosis OR resolution of symptoms suggesting IE owning 4 days of antibiotics OR no pathological evidence of IE at surgery or autopsy within 4 days of antibiotics OR does not meet criteria for possible IE
Describe the management of IE
- Antibiotics
- Large doses of IV antibiotics recommended in all cases
- A Hickman line should be inserted to allow Lon-term administration of antibiotics
- Typical duration therapy is 4-6 weeks - Surgery
- Referral to IE team
a) Describe the regimen for methicillin-sensitive staph.A (MSSA) and methicillin-resistant staph A (MRSA) / penicillin allergy causing IE
b) What must be added in the presence of a prosthetic valve
a) MSSA - Flucloxacillin 12 g/day in 4-6 doses. Duration 4 -6 weeks
MRSA or penicillin allergy - vancomycin 30-60 mg/kg/day on 2-3 doses. Duration 4-6 weeks
b) Rifampicin and gentamicin should be added to both regimens and the duration should be ≥6 weeks.
a) Describe the standard four-week regimen for streptococcal species causing IE
a) Describe the standard two-week regimen for streptococcal species causing IE
c) a) Describe the standard regimen for streptococcal species causing IE in those who are penicillin allergic
a) penicillin G or amoxicillin or cetriaxone
b) penicillin G or amoxicillin or cetriaxone with gentamicin
d) vancomycin for four weeks
When IE is highly suspected, but the organism is not yet known, what can you do and what is the known as?
Give antibiotics following three sets of blood cultures. This known as empirical therapy.
What are in the indications for surgery in infective endocarditis?
- Heart failure
- Uncontrolled infection
- Prevention of embolization (e.g., large vegetations > 10mm)
- Difficult pathogens
- Prosthetic valve endocarditis
Who is involved in the endocarditis team?
- Cardiologist
- Cardiothoracic surgeon
- Microbiologist
- Nurse specialist
Describe the advice you should give to patients to prevent IE
Antibiotic prophylaxis
Maintain a good oral health
- high risk patients should be referred for dental assessment
Advise about risk of invasive procedures
- Such as tattooing or body piercing
IVDU-targeted health promotion
- Needle-change programme
- Education
- Addiction management
a) Prophylactic antibiotics may be given in high-risk or sub-group of high risk patients to prevent IE.
a) Give 4 examples of high risk patients
b) Give 2 examples of sub-groups of high risk patients
c) Give 3 instances when prophylactic antibiotics should not be given
a)
- Cardiac procedures
- Respiratory tract procedures
- Urological procedure
- Obstetric procesdures
b)
- Prosthetic heart valves or material used for cardiac valve repair
- Previous IE
- Congenital heart disease
c)
- Routine dental procedures
- Routine prophylaxis for non-dental procedures
- To cover IE if antimicrobial therapy has been instigated for a GI/GU procedure at a site where there is suspected infection
Describe the complications of IE
Cardiac (50%) - heart failure, preivalvular abscess, pericarditis, cardiac tamponade
Neurological (80% - may be silent) - stroke, abscess, meningitis, encephalitis, haemorrhage, seizures
Metastatic infection - mystic aneurysm, embolization, abscess formation
Embolization sequelae - stroke, blindness, ischaemic limb, splenic/renal infarct, PE, MI
Describe the prognosis of IE
Higher morbidity and mortality in the elderly and in S.auerus, gram-negative and fungal infections
- morbidity usually results from neurological complications (e.g., stroke)
Lower mortality in strep. viridan’s and enterococci
What is the key pathological process in IE
Formation of infected vegetation
Describe how endocardial injury can lead to IE
Endocardial injury leads to thrombus formation
Thrombus is initially sterile and known a s a non-bacterial vegetation
Bacterial invasion of the vegetation (collection of organisms and thrombus) occurs because of microbial component recognised adhesive molecules (MSCRAM)
The infected vegetative thrombus further enlarges secondary to aggregation of platelets and fibrin and is relatively immune fro, host defences
Once deposited on the endocardial surface, the organisms adhere and eventually lead to invasion and destruction of the valve leaflets
What is rheumatic fever?
It is a multi-system disorder that occurs because of an autoimmune reaction to group A streptococcal (GAS) infection
Describe the epidemiology of rheumatic fever
- Common in children aged 5-14 years, rare in those over age 30
- High incidence in developing countries, especially where there is overcrowding and poor access to health care
- Low incidence in developed countries. This is due to the use of antibiotics for bacterial pharyngitis, better hygiene and a declining rheuamtogenic strains of streptococcus
Describe the aetiology of rheumatic fever
- Rheumatogenic strains
- Genetic susceptibility]
- Associated factors e.g. poverty and overcrowded living
Describe the pathophysiology of rheumatic fever
Not completely understood
Describe the clinical features of rheumatic fever
- Typically presents 2-3 weeks after a sore throat from group A strep
- 50% have cardiac involvement
- Developmental heart disease is usually due to recurrent episodes
The diagnosis for acute rheumatic fever is aided using the revised Jones Criteria. It is composed of the major criteria and minor criteria
a) Describe the components of the major criteria
b) Describe the components of the minor criteria
a) CASES
Carditis (40% of patients)
- Breathlessness, palpitation, chest pain, syncope
- Murmurs - mitral regurgitation (most common), aortic regurgitation
- Carey Coombs murmur
- Pericardial rub
Arthritis (75% of patients)
- Acute, migratory polyarthritis
- Joints are red, swollen and tender
- Lasts between one day and four weeks
- Typically affects large joints (knees, ankles, elbows, wrists)
Subcutaneous nodules (10% of patients)
- Small, firm, painless nodules on extensor surface of bones and tendons
- Usually appear more Etna three weeks after onset of manifestations
Erythema marginatum
- Rash with red, raised edges and a clear centre
- Mainly on trunk and proximal extremities (thighs and arms)
Sydenham’s chorea (at least 3 months after acute episode)
- Late manifestation
- Emotional liability followed by involuntary, semi-purposeful movements of hands, feet, or face
- Explosive or halting speech
b) FRAPP
First degree AV block - prolonged PR interval (not if carditis is one of the major criteria)
Raised acute phase reactants - ESR/CRP/leucocytosis
Arthralgia (not if arthritis is one of the major criteria)
Previous rheumatic fever
Prolonged PR interval
How is a diagnosis of rheumatic fever made using the revised Jones Criteria?
- Two major criteria or one major and two minor
PLUS
- Evidence of preceding streptococcal infection
Give 4 differential diagnosis of rheumatic fever
- Infective endocarditis
- Septic arthritis
- Transient synovitis
- Juvenile idiopathic arthritis
- Chorea
Describe the first-lien and second-line investigations for rheumatic fever, including the findings
First line
- Throat swab culture: often negative
- Anti-streptococcal serology
- ECG: AV block, features of pericarditis
- Blood cultures: to exclude infective endocarditis
- Echocardiography: may reveal valvular involvement
Second line
- Systemic autoantibodies in SLE
- Copper and caeruloplasmin for Wilson’s disease
