Rheumatic fever & heart disease – causes, symptoms, diagnosis, treatment, pathology

Rheumatic fever & heart disease – causes, symptoms, diagnosis, treatment, pathology


Learning medicine is hard work! Osmosis makes it easy. It takes your lectures and notes to create
a personalized study plan with exclusive videos, practice questions and flashcards, and so
much more. Try it free today! “Rheumatism” is used to describe inflammation
in the joints, muscles, and the fibrous tissue, so rheumatic fever is a type of inflammatory
disease that can damage the heart tissue, and lead to rheumatic heart disease. Rheumatic fever develops after streptococcal
pharyngitis, inflammation of the throat due to Streptococcus pyogenes where pyogenes literally
means “makes pus”. The bacteria is sometimes referred to as “Group
A beta hemolytic” streptococcus, and the infection itself is most often just called
Strep throat. This particular group of streptococcus has
an antigen that lumps it into a group called “group A”, and it also produces an enzyme
called streptolysin, that completely lyses nearby red blood cells, or causes them rupture—rupturing
red blood cells is called hemolysis, right? And when those red blood cells rupture and
are destroyed, it’s called beta-hemolysis—as opposed to alpha-hemolysis, where cells aren’t
actually destroyed, they’re just damaged or bruised. Some of these strep bacteria have a protein
on their cell wall called “M protein”, and this particular protein is highly antigenic,
meaning that the immune system sees it and recognizes it as a foreign molecule, and mounts
an immune response, which rightfully so, produces antibodies against these proteins. Those antibodies, though, are thought to cross-react
with proteins on some of our body’s own cells, like cells in the myocardium (or heart
muscle) and heart valves, but also cells in the joints, the skin and the brain. This phenomenon, where antibodies accidentally
target proteins on our own cells because they look like the proteins on foreign cells, is
called molecular mimicry, and is an example of what’s called a type 2 hypersensitivity
reaction. Once bound to cardiac tissue, the antibodies
activate nearby immune cells, which causes a cytokine-mediated inflammatory response
and tissue destruction. Obviously though, not everyone that gets strep
throat gets rheumatic fever, and it’s actually only a small minority that get it, estimated
around 3%, and it’s more likely in children or people in areas of poverty and crowding. A lot of patients that do get rheumatic fever
from strep, sometimes called acute rheumatic fever, will have a variety of of clinical
findings. The most common of which is migratory polyarthritis
of the joints—where multiple large joints become inflamed, swollen and painful, one
after another, although this damage isn’t permanent. Secondly, some patients have pancarditis,
or inflammation of all three layers of the heart tissue. The first, endocarditis, is inflammation of
the inner lining which includes the valves. The mitral valve is most commonly affected,
although the aortic valve might also be affected. The next is myocarditis, inflammation of the
myocardium, or heart muscle. Inflamed areas in the myocardial tissue are
called Aschoff bodies, which are areas of fibrinoid necrosis, with immune cells like
T cells and these characteristic Anitschkow cells, enlarged macrophages which have characteristic
caterpillar-looking nuclei. It turns out that myocarditis is the most
common cause of death in acute rheumatic fever because this inflammation and necrosis makes
the heart wall unable to contract with full force, which results in heart failure. Finally there’s pericarditis, or inflammation
of the outer covering of the heart called the pericardium, which can cause pain as well
as a friction rub from the inflamed visceral pericardium rubbing against the inflamed parietal
pericardium- which can be heard with a stethoscope. In addition to joint and heart problems, the
hypersensitivity reaction in rheumatic fever can affect other tissues as well. Patients can develop subcutaneous nodules,
these firm lumps under the skin made up of collagen. They might also have erythema marginatum,
this reddish rash that shows up as rings on the arms or trunk. Also, they could have Sydenham’s chorea,
which is a set of rapid movements of the face and the arms, from an autoimmune reaction
against the basal ganglia of the brain, and this one typically won’t appear until late
in the disease, at least 3 months after infection. These five signs constitute the major diagnostic
criteria for rheumatic fever, which are known as the Jones criteria. The Jones criteria also include having a blood
test that shows evidence of previous streptococcal infection, since these symptoms usually don’t
show up for 2-3 weeks after streptococcal infection. Finally, there are also some minor criteria
that help make the diagnosis—things like fever, joint pain, having more white blood
cells in the blood than usual, elevated acute-phase reactants which are proteins that increase
in the blood in response to inflammation. During inflammation, fibrinogen causes red
blood cells to stick together, these clumped up red blood cells fall to the bottom of a
test tube faster, called the erythrocyte sedimentation rate or ESR, so someone might have an increased
ESR. Finally, due to heart-related symptoms, they
might have changes in their electrocardiogram, or ECG. Acute rheumatic fever usually resolves with
rest, anti-inflammatory treatment, and maybe antibiotics like penicillin to wipe out any
strep that’s hanging out in the throat. It’s worth mentioning that some patients
might only have a subset of symptoms, in which case they might be classified differently. For example, poststreptococcal reactive arthritis
includes patients with joint symptoms and Pediatric autoimmune neuropsychiatric disorders
associated with Streptococcal infections, or PANDAS, includes patients with neuropsychiatric
symptoms. If repeatedly exposed to group A beta-hemolytic
streptococcus, though, the body continues to launch immune attacks against the various
tissues, but most notably the heart tissue—which can lead to chronic rheumatic heart disease. With chronic rheumatic heart disease, the
valves, typically the mitral valve but sometimes the aortic valve, develop scar tissue from
repeated inflammation. The leaflets of the valves become thicker
and can actually fuse together, called commissural fusion, Also the chordae tendinae which are
attached to the valves can become thickened as well. These changes can cause complications with
the valves, most commonly stenosis, or narrowing of the opening, sometimes called “fish-mouth”
stenosis or “buttonhole” stenosis, but it can also cause regurgitation—which is
allowing blood to flow backward. These roughened areas are also at higher risk
of microbial attachment and invasion, called infective endocarditis. Since recurrent attacks of acute rheumatic
fever leads to chronic rheumatic heart disease, a major goal is to prevent these attacks of
acute rheumatic fever, so essentially reducing recurrent streptococcal infections. So depending on the severity of symptoms and
damage to tissue, patients might receive prophylactic antibiotic treatment for long periods of time,
from 10 years to life. Amazingly, resistance to group A Strep to
penicillin hasn’t been a problem after more than 50 years of extensive exposure.

24 Comments

  1. How do you pull it off every time? Each video is informative, fun to watch and easily understandable! Great job osmosis!

  2. I found myself having a difficulty trying to breath, I'm ok And when i'm trying to breath i feel dizzy

    Do you think that I might have any heart problem ?

  3. I love your videos all the time, please do add a summary at the end that helps even more! I hope you do consider it

  4. Same happen with me 4 years ago after marijuna smoke but i didnt know what happen to me disease is progress now and i diagonos with Rhematoid arthritis ๐Ÿ˜ต what's is the treatment now that bacteria didnt die till now

  5. I don't know how to thank you … Fantastic job ๐Ÿ‘ .. i wish you continue your's fantastic knowledge โค๏ธ๐ŸŽˆ

  6. I watch your videos daily.
    Learning would b so amazing if my lecturers teach like you.
    Great job, keep making more videos ๐Ÿ‘๐Ÿ™ŒโœŒ

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