OVERVIEW
Hypereosinophilic syndrome (HES) is a collective term for a group of disorders in which eosinophils are persistently hyperproliferative with multiple organ damage, characterized by peripheral blood eosinophilia as well as infiltration of tissues with eosinophils. In most patients, the cause of the disease is unknown and it is called idiopathic eosinophilia. Some eosinophilia is caused by allergic reactions, autoimmune diseases, tumors (e.g., eosinophilic leukemia), or parasitic infections. Hypereosinophilic syndrome can cause cardiovascular system involvement.
Causes
The cause of hypereosinophilic syndrome is unknown. It is currently believed that IHES is a myeloproliferative disorder, and that its onset is related to parasitic infections and drug- and food-induced allergic reactions. The mechanism of cardiac damage caused by hypereosinophilic syndrome is that eosinophils are overproduced and infiltrate the myocardium due to various reasons, and eosinophil granules are released, and the peroxidase, major basic protein (MBP), cationic protein (ECP), and ethylene glycol dinitrate (EDN) contained in granules are cytotoxic, which can cause damage to tissues, resulting in acute pericarditis, myocarditis, or endocarditis (necrotic heart disease). endocarditis (necrotic phase).
Symptoms
Prevalent in males, more common in middle age and older. The onset of symptoms varies, and they are often nonspecific, including weight loss, fatigue, fever, night sweats, cough, chest pain, myalgia, rash, itchy skin, congestive heart failure, and neuropsychiatric symptoms; 80% of patients have hepatosplenomegaly. Almost all organs can be involved, especially cardiovascular, pulmonary, hematopoietic and neurological involvement is common. The manifestations are endocardial thrombus, endocardial fibrosis, atrioventricular valve regurgitation, restrictive cardiomyopathy and bacterial endocarditis. Neurological symptoms include neuropsychiatric insufficiency, pacemakers, and peripheral neurological symptoms, and hematologic manifestations include anemia, thrombocytopenia, and venous and arterial thrombosis.
Examination
1. X-ray examination: there may be interstitial lung infiltration and pulmonary infarction.
2. White blood cell count: 10×109/L～30×109/L, eosinophils mostly in 30%～70%, eosinophilic late granulocytes and mesophilic granulocytes can be seen in the blood.
3. Electrocardiogram may have non-specific ST-T segment changes.
Diagnosis
The diagnosis of hypereosinophilic syndrome is based on the following points:
1. eosinophilia in the peripheral blood cannot be explained by other etiologies.
2. long duration of the disease, with prolonged and persistent eosinophilia for more than half a year.
3. Eosinophilia: eosinophil count more than 1.5×109/L or more.
4. Damage to more than one internal organ. If a patient with eosinophilia meets the above criteria, it can be considered as hypereosinophilic syndrome.
Treatment
Pharmacologic treatment in the early stages of hypereosinophilic syndrome and surgical treatment in the more advanced stages of fibrosis are effective in improving symptoms and prognosis. Hormones are the treatment of choice for acute endocarditis, and the combination of hormones and cytotoxic drugs (especially hydroxyurea) often improves prognosis. Prednisone is often used until eosinophils are normalized and then tapered. Interferon is effective in a small number of patients who respond poorly to standard therapy. Digoxin, diuretics, afterload reduction, and anticoagulation may be routinely given to patients with cardiovascular involvement associated with cardiac insufficiency, depending on the condition. Once the fibrotic stage is reached, fibrotic endocardial resection and mitral or tricuspid valve replacement can often provide significant symptomatic relief.