Download 2) Angioedema – Dr. Bakhtiar Definition • Angioedema or Quincke`s

2) Angioedema – Dr. Bakhtiar
Definition
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Angioedema or Quincke's edema is the rapid swelling (edema) of the dermis, subcutaneous tissue,mucosa
and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in
the upper dermis. The term angioneurotic oedema was used for this condition in the belief that there was
nervous system involvement but this is now thought not to be the case.
Cases where angioedema progresses rapidly should be treated as a medical emergency as airway
obstruction and suffocation can occur. Epinephrine may be lifesaving when the cause of angioedema is
allergic. In the case of hereditary angioedema, treatment with epinephrine has not been shown to be
helpful.
Classification
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Apart from the common form, mediated by allergy, it has been reported as a side effect of some
medications, in particular ACE inhibitors. Additionally, there are three autosomal dominant inherited
forms known, due to mutations in the genes that control the clotting cascade, including the SERPING1
gene, which results in deficiency of the blood protein C1-inhibitor (type I HAE) and the F12 gene, which
controls Factor XII (type III HAE). There is an additional type in which C1 levels are normal but C1
function is decreased (type II HAE). All three forms are called hereditary angioedema (HAE) or
occasionally by the outdated term "hereditary angioneurotic edema" (HANE). In all forms of HAE,
swelling may also occur in the digestive tract and other organs. It is life-threatening when it involves the
larynx due to the potential for asphyxiation.
Signs and symptoms
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The skin of the face, normally around the mouth, and the mucosa of the mouth and/or throat, as well as
the tongue, swell up over the period of minutes to several hours. The swelling can also occur elsewhere,
typically in the hands. The swelling can be itchy or painful. There may also be slightly decreased sensation
in the affected areas due to compression of the nerves. Urticaria (hives) may develop simultaneously.
In severe cases, stridor of the airway occurs, with gasping or wheezy inspiratory breath sounds and
decreasing oxygen levels. Tracheal intubation is required in these situations to prevent respiratory arrest
and risk of death.
Sometimes, there has been recent exposure to an allergen (e.g. peanuts), but more often the cause is either
idiopathic (unknown) or only weakly correlated to allergen exposure.
In hereditary angioedema, there is often no direct identifiable cause, although mild trauma, including dental work
and other stimuli, can cause attacks. 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, non-itchy
splotchy/swirly rash. These stomach attacks can last anywhere from 1–5 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 13-30,000. 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.
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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.
Diagnosis
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The diagnosis is made on the clinical picture. Routine blood tests (complete blood count, electrolytes,
renal 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.
Pathophysiology
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Bradykinin plays a critical role in all forms of hereditary angioedema.This peptide is a potent vasodilator
and increases vascular permeability, leading to rapid accumulation of fluid in the interstitium. This is most
obvious in the face, where the skin has relatively little supporting connective tissue, and edema develops
easily. Bradykinin is released by various cell types in response to numerous different stimuli; it is also a
pain mediator. Dampening or inhibiting bradykinin has been shown to relieve HAE symptoms.
Various mechanisms that interfere with bradykinin production or degradation can lead to angioedema.
ACE inhibitors block ACE, the enzyme that among other actions, degrades bradykinin. In hereditary
angioedema, bradykinin formation is caused by continuous activation of the complement system due to a
deficiency in one of its prime inhibitors, C1-esterase (aka: C1-inhibitor or C1INH), and continuous
production of kallikrein, another process inhibited by C1INH. This serine protease inhibitor (serpin)
normally inhibits the association of C1r and C1s with C1q to prevent the formation of the C1-complex,
which - in turn - activates other proteins of the complement system. Additionally, it inhibits various
proteins of the coagulation cascade, although effects of its deficiency on the development of hemorrhage
and thrombosis appear to be limited.
Types of hereditary Angioedema
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Type I - decreased levels of C1INH (85%);
Type II - normal levels but decreased function of C1INH (15%);
Type III - no detectable abnormality in C1INH, occurs in an X-linked dominant fashion and therefore
mainly affects women; it can be exacerbated by pregnancy and use of hormonal contraception.It has been
linked with mutations in the factor XII gene.
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Angioedema can be due to antibody formation against C1INH; this is an autoimmune disorder. This
acquired angioedema is associated with the development of lymphoma.
Consumption of foods which are themselves vasodilators such as alcohol or cinnamon can increase the
probability of an angioedema episode in susceptible patients. If the episode occurs at all after the
consumption of these foods, its onset may be delayed overnight or by some hours, making the correlation
with their consumption somewhat difficult. In contrast, consumption of bromelain in combination with
turmeric may be beneficial in reducing symptoms.
The use of ibuprofen or aspirin may increase the probability of an episode in some patients. The use of
acetaminophen typically has a smaller, but still present, increase in the probability of an episode.
Management
Allergic
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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.
Drug induced
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ACE inhibitors can induce angioedema.ACE inhibitors block the enzyme ACE so that it can no longer
degrade bradykinin; thus bradykinin accumulates and causes angioedema. This complication appears
more common in African-Americans. In patients with ACE inhibitor angioedema, the drug needs to be
discontinued and an alternate 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
there are small studies that have shown that patients with ACE inhibitor angioedema can develop it with
ARBs as well.
Hereditary
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In hereditary angioedema, 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
o The aim of acute treatment is to halt progression of the edema as quickly as possible, which can
be life-saving, particularly if the swelling is in the larynx. In Germany, most acute treatment
consists of C1-INH 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. Fresh frozen plasma (FFP) can be used as an alternative to C1-INH
concentrate.
Long-term prophylaxis of hereditary angioedema
o Patients in whom episodes occur at least once a month or who are at high risk of developing
laryngeal edema require long-term prophylaxis. This often involves male sex hormones
(androgens), which increase production of C1-INH in the liver through an as yet unknown
mechanism. Danazol is the most commonly used.The dose should be kept as low as possible
because of its frequent adverse effects. The use of androgens is particularly problematic in children
and they must not be taken during pregnancy. Several cases in which patients developed benign
liver tumours during treatment with danazol resulted in the substance being taken off the market
in Germany at the beginning of 2005.
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o As an alternative, drugs known as fibrinolysis inhibitors, such as tranexamic acid, are used,
although their effect is comparatively weak and their potential for side effects is questionable. In
those with frequent or unpredictable attacks, regular infusions of plasma or inhibitor concentrate
may be used.C1-INH concentrate is not available in the US, so sometimes fresh frozen plasma is
used. C1inh concentrate is currently under late-stage development for both acute and prophylactic
use
Short-term prophylaxis of hereditary angioedema
o Short-term prophylaxis is normally administered before surgery or dental treatment. In Germany,
C1-INH concentrate is used for this and given 1-11/2 hours before the procedure. In countries
where C1-inhibitor concentrate is not available or only available in an emergency (laryngeal
edema), high-dose androgen treatment is administered for 5–7 days
New treatment options
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Clinical development of several new active substances, which intervene in the disease process in different
ways, is currently ongoing.
Ecallantide is a peptide inhibitor of kallikrein that has received orphan status for HAE and has shown
positive results in phase III trials.
Icatibant (marketed as Firazyr) is a selective bradykinin receptor antagonist, which has been approved in
only Europe and not in the USA.After initial borderline results this drug was shown to be effective in
phase III trials.
Acquired
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In acquired angioedema, HAE types I and II, and non-histaminergic 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 while androgens cannot.
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