Наследственный ангионевротический отек: симптомы, диагностика и лечение.

Disease characterized by rapid swelling
Treatment to protect the airway may include intubation or cricothyroidotomy. There is usually no associated itch or urticaria, as it is not an allergic response. Patients with HAE can also have recurrent episodes (often called "attacks") of abdominal pain, usually accompanied by intense vomiting, weakness, and in some cases, watery diarrhea, and an unraised, nonitchy splotchy/swirly rash. These stomach attacks can last one to five days on average and can require hospitalization for aggressive pain management and hydration. Abdominal attacks have also been known to cause a significant increase in the patient's white blood cell count, usually in the vicinity of 13,000 to 30,000. As the symptoms begin to diminish, the white count slowly begins to decrease, returning to normal when the attack subsides. As the symptoms and diagnostic tests are almost indistinguishable from an acute abdomen (e. g. perforated appendicitis) it is possible for undiagnosed HAE patients to undergo laparotomy (operations on the abdomen) or laparoscopy (keyhole surgery) that turns out to have been unnecessary. HAE may also cause swelling in a variety of other locations, most commonly the limbs, genitals, neck, throat and face. The pain associated with these swellings varies from mildly uncomfortable to agonizing pain, depending on its location and severity. Predicting where and when the next episode of edema will occur is impossible. Most patients have an average of one episode per month, but there are also patients who have weekly episodes or only one or two episodes per year. The triggers can vary and include infections, minor injuries, mechanical irritation, operations or stress. In most cases, edema develops over a period of 12–36 hours and then subsides within 2–5 days.

The diagnosis is made on the clinical picture. Routine blood tests (complete blood count, electrolytes, kidney function, liver enzymes) are typically performed. Mast cell tryptase levels may be elevated if the attack was due to an acute allergic (anaphylactic) reaction. When the patient has been stabilized, particular investigations may clarify the exact cause; complement levels, especially depletion of complement factors 2 and 4, may indicate deficiency of C1 inhibitor. HAE type III is a diagnosis of exclusion consisting of observed angioedema along with normal C1 levels and function. The hereditary form (HAE) often goes undetected for a long time, as its symptoms resemble those of more common disorders, such as allergy or intestinal colic. An important clue is the failure of hereditary angioedema to respond to antihistamines or steroids, a characteristic that distinguishes it from allergic reactions. It is particularly difficult to diagnose HAE in patients whose episodes are confined to the gastrointestinal tract. Besides a family history of the disease, only a laboratory analysis can provide final confirmation. In this analysis, it is usually a reduced complement factor C4, rather than the C1 INH deficiency itself, that is detected. The former is used during the reaction cascade in the complement system of immune defense, which is permanently overactive due to the lack of regulation by C1 INH. Angioedema is classified as either hereditary or acquired.

Acquired angioedema (AAE) can be immunologic, nonimmunologic, or idiopathic. It is usually caused by allergy and occurs together with other allergic symptoms and urticaria. It can also occur as a side effect to certain medications, particularly ACE inhibitors. It is characterized by repetitive episodes of swelling, frequently of the face, lips, tongue, limbs, and genitals. Edema of the gastrointestinal mucosa typically leads to severe abdominal pain; in the upper respiratory tract, it can be life threatening.

Hereditary angioedema (HAE) exists in three forms, all of which are caused by a genetic mutation inherited in an autosomal dominant form. They are distinguished by the underlying genetic abnormality. Types I and II are caused by mutations in the SERPING1 gene, which result in either diminished levels of the C1 inhibitor protein (type I HAE) or dysfunctional forms of the same protein (type II HAE). Type III HAE has been linked with mutations in the F12 gene, which encodes the coagulation protein factor XII. All forms of HAE lead to abnormal activation of the complement system, and all forms can cause swelling elsewhere in the body, such as the digestive tract. If HAE involves the larynx, it can cause life threatening asphyxiation. The pathogenesis of this disorder is suspected to be related to unopposed activation of the contact pathway by the initial generation of kallikrein and/or clotting factor XII by damaged endothelial cells. The end product of this cascade, bradykinin, is produced in large amounts and is believed to be the predominant mediator leading to increased vascular permeability and vasodilation that induces typical angioedema "attacks".

In allergic angioedema, avoidance of the allergen and use of antihistamines may prevent future attacks. Cetirizine is a commonly prescribed antihistamine for angioedema. Some patients have reported success with the combination of a nightly low dose of cetirizine to moderate the frequency and severity of attacks, followed by a much higher dose when an attack does appear. Severe angioedema cases may require desensitization to the putative allergen, as mortality can occur. Chronic cases require steroid therapy, which generally leads to a good response. In cases where allergic attack is progressing towards airway obstruction, epinephrine may be life saving.

ACE inhibitors can induce angioedema. ACE inhibitors block the enzyme ACE so it can no longer degrade bradykinin; thus, bradykinin accumulates and can cause angioedema. This complication appears more common in African Americans. In people with ACE inhibitor angioedema, the drug needs to be discontinued and an alternative treatment needs to be found, such as an angiotensin II receptor blocker (ARB), which has a similar mechanism but does not affect bradykinin. However, this is controversial, as small studies have shown some patients with ACE inhibitor angioedema can develop it with ARBs, as well.

In hereditary angioedema (HAE), specific stimuli that have previously led to attacks may need to be avoided in the future. It does not respond to antihistamines, corticosteroids, or epinephrine. Acute treatment consists of C1 INH (C1 esterase inhibitor) concentrate from donor blood, which must be administered intravenously. In an emergency, fresh frozen blood plasma, which also contains C1 INH, can also be used. However, in most European countries, C1 INH concentrate is only available to patients who are participating in special programmes. The medications ecallantide and icatibant may be used to treat attacks. In those given icatibant, specialists monitor is recommended.

In acquired angioedema, HAE types I and II, and nonhistaminergic angioedema, antifibrinolytics such as tranexamic acid or ε aminocaproic acid may be effective. Cinnarizine may also be useful because it blocks the activation of C4 and can be used in patients with liver disease, whereas androgens cannot.

Future attacks of HAE can be prevented by the use of androgens such as danazol, oxandrolone or methyltestosterone. These agents increase the level of aminopeptidase P, an enzyme that inactivates kinins; kinins (especially bradykinin) are responsible for the manifestations of angioedema. In 2018, the U. S. Food and Drug Administration approved lanadelumab, an injectable monoclonal antibody, to prevent attacks of HAE types I and II in people over age 12. Lanadelumab inhibits the plasma enzyme kallikrein, which liberates the kinins bradykinin and kallidin from their kininogen precursors and is produced in excess in individuals with HAE types I and II.

In the U. S., there are as many as 80,000 to 112,000 emergency department (ED) visits for angioedema annually, and it ranks as the top allergic disorder resulting in hospitalization.

Heinrich Quincke first described the clinical picture of angioedema in 1882, though there had been some earlier descriptions of the condition. William Osler remarked in 1888 that some cases may have a hereditary basis; he coined the term "hereditary angio neurotic edema". The link with C1 esterase inhibitor deficiency was proved in 1963.