AssessmentsRheumatic heart disease
Rheumatic heart disease
USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A 10-year-old girl comes to the clinic because of involuntary movement of her face and extremities for the past 2 weeks. Her mother mentions the patient was treated for a sore throat 2 months ago. Physical examination shows slurred speech, poor finger-to-nose coordination, and inability to clench her fists for prolonged periods. Oropharyngeal examination shows no abnormalities. Laboratory tests show elevated anti-streptolysin O. An echocardiogram shows mild mitral regurgitation and a thickened mitral valve. Which of the following is the most likely diagnosis?
“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.
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.