Rheumatic endocarditis - Erler Zimmer
Clinical History
A 52-year-old woman presented with worsening dyspnoea. She reported a history of childhood fever and flitting joint pains following a sore throat. Upon examination, she exhibited cyanosis, atrial fibrillation on pulse assessment, elevated jugular venous pulse, a pan-systolic murmur at the apex, hepatomegaly, and dependent oedema. Despite treatment with digoxin, lasix (furosemide), and penicillin, she succumbed to cardiac arrest.
Pathology
The specimen features a heart opened to reveal the left atrium and left ventricle. The mitral valve, although cut, displays significant thickening in visible parts. The left atrial wall exhibits blood and fibrin deposition, and the left auricular appendage contains a blood clot attributed to atrial fibrillation. Notably, the mural thrombus on the atrial wall is situated in the characteristic site—deep layers of the endocardium forming irregular thickenings known as MacCallum’s plaques (marked by arrows).
Further Information
In this case, the history of childhood fever and joint pains following a sore throat strongly suggests a past episode of rheumatic fever. Rheumatic fever, an inflammatory condition, can affect the heart, joints, skin, and brain. Symptoms may include fever, painful joints, involuntary muscle movements (chorea), and occasionally a distinctive non-itchy rash known as 'erythema marginatum.'
Rheumatic fever can develop 2-4 weeks after a Streptococcus pyogenes throat infection. Without proper treatment (penicillin), up to three percent of individuals may develop rheumatic fever. The underlying mechanism involves the production of antibodies against the person's own tissues, leading to autoimmune disease. Genetic factors, malnutrition, and poverty, more prevalent in low to middle-income countries and Indigenous communities, contribute to the risk.
The heart is involved in about half of rheumatic fever cases, resulting in rheumatic heart disease (RHD). Damage to the heart valves, particularly the mitral valve, occurs after repeated attacks (carditis) and can progress to chronic rheumatic heart disease. The presented specimen highlights mitral valve thickening, likely due to Aschoff nodules—granulomatous lesions with central fibrinoid necrosis surrounded by autoreactive T cell infiltration. 'Giant cells' within Aschoff nodules suggest degenerative connective or endothelial tissue.
As mitral stenosis worsens over the years, the left atrium dilates, leading to atrial fibrillation and the formation of mural thrombi. Severe cardiac failure can result from tight mitral stenosis.
