Valvular heart disease, endocarditis Flashcards
Learning objectives
- Define the terms stenosis and incompetence
- Describe the common causes of cardiac valve stenosis and incompetence
- Define the term infective endocarditis
- Name some risk factors for infective endocarditis
- Describe the composition of a vegetation
- Name some probable causative organisms
- Describe the local and systemic complications of infective endocarditis
- Describe the principles of diagnosis, treatment and prevention of infective endocarditis
How much of an issue is valvular heart disease?
- 10% of heart failure involves valve disease
- Four valves – all can be affected
- Primary and secondary problems
Discuss the structure and function of the heart valves
Components: Valve ring Cusp Chordae Papillary muscles (mitral + tricuspid only)
Functions:
To allow forward flow but prevent back flow of blood
What is a functional failure in valves?
Mitral stenosis
Mitral incompetence
Aortic stenosis
Aortic incompetence
Tricuspid and pulmonary valve as above but less common and less severe disease
Define stenosis and incompetence
• Stenosis
Narrowing of the valve outlet caused by thickening of valve cusps, or increased rigidity or scarring.
• Incompetence
Or insufficiency or regurgitation (which is what happens) caused by incomplete seal when valves close, allowing blood to flow backwards
Remember vegetations
Discuss the valves in relation to heart sounds and the signs you can pick up for valvular disease
- First: mitral and tricuspid - systole
- Second: aorta and pulmonary – diastole
Signs • Aortic stenosis • Aortic incompetence • Mitral stenosis • Mitral incompetence
What are common causes of cardiac valve stenosis and incompetence
- Congenital heart disease: bicuspid valve, atresia
- Cardiomyopathy (hypertrophic, dilated)
• Acquired – Rheumatic fever – Myocardial infarction – Age related – idiopathic aortic calcific stenosis – Endocarditis
What are the risks of aortic stenosis?
Left ventricular hypertrophy
Syncope
Sudden cardiac death
What are the causes of aortic stenosis?
Calcification of congenital bicuspid valve
Senile calcific degeneration
Rheumatic fever
What are the consequences of aortic stenosis?
Increases the work of the heart
Ventricular hypertrophy
Causes cardiac failure late in the clinical course
Clinical symptoms include:
Dyspnoea
Angina
Syncope
What are causes of aortic incompetence?
Infective endocarditis
Rheumatic fever
Marfan’s syndrome
What are the consequences of aortic regurgitation?
Increase the volume of blood to be pumped significantly
Increases the work of the heart
Cardiac hypertrophy
Cardiac failure
Can occur in the presence of aortic stenosis
What are the causes of mitral incompetence?
• Cusp damage – for example
– Rheumatic heart disease – scarring, contraction
– Floppy valve & Marfan syndrome - stretch
– Infective endocarditis - perforation
- Chordae – as above
- Papillary muscle – eg post MI
- Valve ring – as above, age
Most often post-rheumatic fever
What are the risks if mitral incompetence?
Pulmonary hypertension Right ventricular hypertrophy
Discuss mitral stenosis
Congenital (rare)
Post rheumatic fever (rare in developed countries)
Restricts blood flow to the left ventricle
Atrial fibrillation
Back pressure results in pulmonary hypertension
Finally cause right hear t failure
Define infective endocarditits
• Infection of valve with formation of thrombotic vegetations • Virulence of organisms determines damage and severity of the clinical illness • Classified as acute and sub-acute • Bacteraemia is common
What are the risk factors for infective endocarditis
• Valve damage
– As before, especially after rheumatic fever
• Bacteraemia – Dental – Catheterisation – 10% unknown – iv drug abuse
• Immunosuppression
Discuss rheumatic fever
- Acute multisystem disease – heart (myocarditis, valvulitis, pericarditis), joints, connective tissue
- 3 weeks post Streptococcal infection (usually pharyngitis)
- Immune mediated rather than direct infection
- Occurs in children: 4-16 years
- May occur in recurrent episodes
- Chronic valve disease decades later
What is the composition of a vegetation
Group D Streptococcus, gut commensals, skin Strep
Coxiella, fungi, Candida
What are the local and systemic complications of infective endocarditis
many
Cerebral and retinal emboli
Bronchopneumonia Pulmonary infarct (tricuspid valve endocarditis)
Myocarditis
Renal infarcts
Glomerulonephritis
Splenomegaly +-infarcts
Anaemia
Clubbing
Splinter haemorrhages
Immune Infective Thrombotic
Discuss acute native valve endocarditis
– valves may be normal
– aggressive disease
– virulent organisms, such as Staph. aureus and
group B streptococci
Discuss subacute native valve endocarditis
– abnormal valves
– indolent but may deteriorate
– alpha-haemolytic streptococci, enterococci
Discuss prosthetic valve endocarditis
– 10-20% of cases
– 5% of mechanical and bio-prosthetic valves become infected
– mitral are more susceptible than aortic
– early onset: Staph. aureus, gram-negative bacilli,
Candida species
– late onset: staphylococci, alpha-haemolytic streptococci, enterococci
Discuss IV drug abuse in valvular heart disease
– 75% have no underlying valvular abnormalities
– 50% involve the tricuspid valve
– Staph. aureus most common
What are the principles of diagnosis, treatment and prevention of infective endocarditis
• Treat Strep. infection with antibiotics • Prophylactic cover for invasive procedures eg dental work • Replacedamagedvalves • Clinical suspicion & signs • Imaging – especially echocardiography • BLOOD CULTURE • IV ANTIBIOTICS
