Rheumatic Fever
Rheumatic fever is actually not a disease, but a symptom of one. Essentially, following an untreated infection by β-haemolytic streptococcus group A (e.g. S. pyogenes), the antibodies that were used to fight the disease might turn around to fight the tissues, causing systemic inflammation that affects the heart and other organs. This inflammatory condition, rheumatic fever, tends to occur mainly in children 5-15 years of age.
Rheumatic fever can be responsible for cardiac lesions. It can cause pericarditis, which may come with effusion of fluid, which in turn may impair cardiac filling. It can also cause myocarditis, which can be definitively diagnosed by Aschoff bodies. Aschoff bodies are granulomas consisting of fibrous tissue, lymphocytes and abnormal macrophages. They are pathognomonic to rheumatic fever-induced myocarditis- that is, they only occur in this particular condition. Finally, rheumatic fever can also cause endocarditis, which is the most common problem.
Endocarditis can result in valvular lesions, which usually result in permanent damage. The mitral valve is the most commonly affected, followed by the aortic valve. Sometimes little wart-like vegetations called verrucae form along the outer edges of the cusps. Valvular lesions often result in stenosis (i.e. valves become stiff and blood doesn't readily move through) or incompetence (valves allow too much backflow of blood). Endocarditis from rheumatic fever can also increase the risk of infective endocarditis, a condition that I'll go into more depth later.
Rheumatic fever can also be responsible for extra-cardiac lesions. In joints, it can cause polyarthritis. This tends to affect larger joints such as the knees and ankles and is fleeting- that is, it moves from place to place. It is also unlikely to cause permanent damage. In the skin, rheumatic fever can cause erythema margninatum, which is a red, non-pruritic (i.e. not itchy) rash with a pale centre, as well as subcutaneous nodules, which are little PAINLESS lumps under the skin. (I've put "painless" in capital letters because soon I'll be introducing you to painful ones in a different condition.) A late sign of rheumatic fever is Sydenham's chorea, characterised by semi-purposeful movements (I *think* that means "involuntary movements that look well-coordinated," but I'm not sure). Sydenham's chorea is a result of lesions in the basal nuclei.
Other manifestations of rheumatic fever include low grade fever, loss of appetite, fatigue, dyspnea, and so on. There are, however, specific criteria to look for when making a diagnosis. First are the five major criteria:
Rheumatic fever can be responsible for cardiac lesions. It can cause pericarditis, which may come with effusion of fluid, which in turn may impair cardiac filling. It can also cause myocarditis, which can be definitively diagnosed by Aschoff bodies. Aschoff bodies are granulomas consisting of fibrous tissue, lymphocytes and abnormal macrophages. They are pathognomonic to rheumatic fever-induced myocarditis- that is, they only occur in this particular condition. Finally, rheumatic fever can also cause endocarditis, which is the most common problem.
Endocarditis can result in valvular lesions, which usually result in permanent damage. The mitral valve is the most commonly affected, followed by the aortic valve. Sometimes little wart-like vegetations called verrucae form along the outer edges of the cusps. Valvular lesions often result in stenosis (i.e. valves become stiff and blood doesn't readily move through) or incompetence (valves allow too much backflow of blood). Endocarditis from rheumatic fever can also increase the risk of infective endocarditis, a condition that I'll go into more depth later.
Rheumatic fever can also be responsible for extra-cardiac lesions. In joints, it can cause polyarthritis. This tends to affect larger joints such as the knees and ankles and is fleeting- that is, it moves from place to place. It is also unlikely to cause permanent damage. In the skin, rheumatic fever can cause erythema margninatum, which is a red, non-pruritic (i.e. not itchy) rash with a pale centre, as well as subcutaneous nodules, which are little PAINLESS lumps under the skin. (I've put "painless" in capital letters because soon I'll be introducing you to painful ones in a different condition.) A late sign of rheumatic fever is Sydenham's chorea, characterised by semi-purposeful movements (I *think* that means "involuntary movements that look well-coordinated," but I'm not sure). Sydenham's chorea is a result of lesions in the basal nuclei.
Other manifestations of rheumatic fever include low grade fever, loss of appetite, fatigue, dyspnea, and so on. There are, however, specific criteria to look for when making a diagnosis. First are the five major criteria:
- Carditis
- Polyarthritis
- Erythema marginatum
- Subcutaneous nodules
- Sydenham chorea
And a few minor criteria:
- Fever
- Arthralgia
- History of rheumatic fever
- Acute phase reaction (i.e. elevated C-reactive protein, ESR, leukocytosis)
- ECG changes (e.g. increased PR interval)
The Modified Jones Criteria state that you need either two major criteria and evidence of streptococcal infection, OR one major and two minor criteria and evidence of streptococcal infection in order to diagnose rheumatic fever. Evidence of strep infection can be found by taking a titer of antistreptolysin O (ASO) antibodies.
Treatment of rheumatic fever involves treating the streptococcal infection with antibiotics. Long-acting antibiotics might also be used as prophylaxis if someone with an infection hasn't developed rheumatic fever yet. Acute carditis can be treated with aspirin and corticosteroids, and drug and surgery treatments can be used to treat long-term cardiac damage.
Infective Endocarditis
Infective endocarditis is, well, endocarditis due to infection. The most common type of infectious organism involved is bacteria, but fungi and viruses can play a role too. Subacute infective endocarditis is caused by non-virulent bacteria such as S. viridians, whereas acute infective endocarditis is caused by more highly virulent bacteria such as S. aureus.
So how does the bacteria do its damage? Well, usually there's a little bit of damage in the heart first, like a valve lesion. Or maybe there is bacteraemia, or bacteria in the blood. Diseases in which immune function is impaired, like AIDS, can also leave people open to infection.
Just like in rheumatic heart disease (RHD) endocarditis, infective endocarditis can lead to vegetations on the valve cusps. These vegetations are composed of fibrin strands, platelets, other blood cells and microorganisms. They can break away, forming septic emboli which cause infections in other places.
Manifestations of infective endocarditis include more general stuff like fever, malaise, fatigue and anorexia (loss of appetite), but there's some other stuff to look out for too. Roth's spots are retinal haemorrhages and Osler's nodes are PAINFUL, red nodules on hands and feet (again, I capitalised painful in order to distinguish them from the painless subcutaneous nodules of RHD). Septic emboli may also cause complications such as abscesses and organ infarctions. Nasty stuff.
Diagnosis of infective endocarditis can be done by echocardiography to look for valve lesions, as well as blood culture in order to detect the organism. Treatment includes antibiotics as well as other kinds of supportive therapy. Surgical repair may be required if serious.
Pericarditis
Pericarditis, inflammation of the pericardium, can be due to a range of causes. It may follow myocardial infarction (in which case it's called Dressler syndrome), rheumatic fever, renal failure, infection, and so on.
Pericarditis can be categorised in several different ways. It can be acute or chronic, acute being more common. Acute pericarditis can lead to cardiac tamponade (lots of pericardial effusion in a short amount of time), while chronic pericarditis can lead to constrictive pericarditis. Pericarditis can be dry or wet. In dry pericarditis there is a lot of fibrous tissue which causes friction in the heart, while in wet pericarditis there is a lot of effusion. Finally, pericarditis can also be categorised according to the composition of the fluid: serous, purulent, fibrinous or haemorrhagic.
Manifestations of pericarditis include chest pain, tachycardia, palpitations, dyspnea, cough and distended neck veins. If there is a lot of effusion, heart sounds may be faint as they have to travel through more fluid. In dry pericarditis, a "friction rub" may also be heard. If cardiac tamponade is present, pulsus paradoxus can occur. Pulsus paradoxus is when your systolic blood pressure drops by more than 10mmHg during inspiration- pretty nasty.
Pericarditis can be diagnosed by pericardiocentesis (aspiration of fluid from the pericardial space) and analysis of the pericardial fluid, as well as by our friends the chest X-ray and the echocardiogram. It can be treated by pericardiocentesis, as well as antibiotics, steroids or even pericardiectomy (removal of a portion or all of the pericardium).
Myocarditis
Myocarditis is inflammation of the myocardium. Once again, the usual culprits causing this condition are infections (viral being the most common here) and rheumatic fever, along with radiation and toxins such as alcohol. It manifests in chest pain, palpitation and so on. It can be diagnosed with ECG and by looking for cardiac markers in blood tests. As it is usually caused by a virus, there are no specific measures for treating myocarditis. General cardiac supportive therapy might help, though.
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