Leaky artificial heart valve triggers rare aHUS in woman, 70: Report
Treatment with Soliris alongside valve repair effectively resolves symptoms
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Leakage in an artificial heart valve appeared to trigger atypical hemolytic uremic syndrome (aHUS) in a 70-year-old woman who had no disease-related genetic mutations, a team of researchers noted in a new report, saying the case highlights the importance of a full examination for individuals suspected of having the rare condition.
The patient, treated in a hospital in Poland, underwent a minimally invasive procedure to repair the prosthesis and was also given the approved aHUS therapy Soliris (eculizumab). The combination rapidly resolved the woman’s clinical symptoms, according to the researchers.
The team noted that their findings ultimately suggest that “valve dysfunction may have acted as a cofactor rather than a direct cause” of the woman’s aHUS.
Still, “this case emphasizes the need for comprehensive evaluation and a multidisciplinary approach in diagnosing and treating aHUS, especially in patients with multiple [coexisting conditions] and complicated medical history,” the researchers wrote.
Case details were described in the study, “Diagnostic Challenges in Atypical Hemolytic Uremic Syndrome: A Case of Artificial Mitral Valve Dysfunction as a Possible Trigger for Severe Thrombotic Microangiopathy,” published in the American Journal of Case Reports.
aHUS is a type of thrombotic microangiopathy, a group of conditions marked by the formation of blood clots in small blood vessels, leading to organ damage, primarily affecting the kidneys. It’s caused by abnormal activity of the complement cascade, a component of the immune system. Patients often experience hemolytic anemia, or red blood cell destruction, and thrombocytopenia, meaning that they have low levels of platelets, the cell fragments that help blood to clot. For some individuals, aHUS can potentially result in kidney failure.
Most people with aHUS are born with defects in genes that regulate the complement cascade. However, having these gene mutations does not always mean a person will develop aHUS. In most cases, another event, such as an infection, autoimmune diseases, pregnancy, or certain medications, serves as a trigger.
aHUS can occur even without a genetic cause
Sometimes, aHUS can develop even when no clear genetic cause is found, as in the case of this older woman, whose aHUS was triggered by a leaky artificial heart valve, according to the researchers.
In 1998, she underwent implantation of an artificial valve to replace the mitral valve between the heart’s upper and lower left chambers. Afterward, she received long-term treatment with warfarin, an anticoagulant (blood thinner) to prevent blood clotting complications.
More recently, she began to experience malaise, shortness of breath, recurrent episodes of bleeding inside the mouth, and blood in the urine. A physical examination revealed significant swelling of the lower extremities, as well as muffled breath sounds and crackles.
Blood tests showed anemia — low levels of hemoglobin, the protein that carries oxygen in red blood cells — mild thrombocytopenia, and evidence of hemolysis. All complement-related proteins were normal, except for one known as sC5b-9, which was elevated, suggesting complement overactivation.
A battery of additional tests ruled out other aHUS triggers, including infections, autoimmune diseases, sepsis, cancer, and coagulopathy, or impaired blood clotting. Genetic tests also failed to detect mutations in complement-related genes.
Initial treatment involved supportive care, fluid balance monitoring, blood pressure control, and a red blood cell transfusion. Given her severe symptoms, she began a treatment regimen with Soliris, which rapidly reduced hemolysis, improved kidney function and platelet count, and resolved her clinical symptoms.
Patient remained free of symptoms after stopping Soliris
Due to her previous heart valve replacement, clinicians conducted an echocardiogram of the heart. The test detected perivalvular leakage, in which blood flows around rather than through the artificial heart valve.
As a result, the patient underwent intravascular mitral valve repair, a minimally invasive procedure that uses a catheter inserted through a blood vessel and into the heart to fix the valve.
“The [developmental pathway] of aHUS triggered by artificial valve [leakage] remains unclear but may involve turbulence-induced microangiopathy,” the team wrote.
Soliris was discontinued after three months, and the woman remained free of symptoms. However, she died a month later due to heart failure.
“This case provides clinical evidence of a potential link between [a valve] leak and the development of thrombotic microangiopathy,” the researchers wrote. “However, these findings indicate an association rather than confirmed relationship.” The team suggested that the issue “may have contributed to and exacerbated cardiac dysfunction.”
