Hereditary hemorrhagic telangiectasia
Hereditary hemorrhagic telangiectasia: Excerpt from Professional Guide to Diseases (Eighth Edition)
Hereditary hemorrhagic telangiectasia (also called Osler-Weber-Rendu syndrome) is an inherited vascular disorder in which venules and capillaries dilate to form fragile masses of thin convoluted vessels (telangiectases), resulting in an abnormal tendency to hemorrhage. This disorder affects both sexes but may cause less severe bleeding in females.
Causes
Hereditary hemorrhagic telangiectasia is transmitted by autosomal dominant inheritance. It seldom skips generations. In its homozygous state, it may be lethal.
Signs and symptoms
Signs of hereditary hemorrhagic telangiectasia are present in childhood but increase in severity with age. Localized aggregations of dilated capillaries appear on the skin of the face, ears, scalp, hands, arms, and feet; under the nails; and on the mucous membranes of the nose, mouth, and stomach. These dilated capillaries cause frequent epistaxis, hemoptysis, and GI bleeding, possibly leading to iron deficiency anemia. (In children, epistaxis is usually the first symptom.)
Characteristic telangiectases are violet, bleed spontaneously, may be flat or raised, blanch on pressure, and are nonpulsatile. They may be associated with vascular malformations such as arteriovenous fistulas. Visceral telangiectases are common in the liver, bladder, respiratory tract, and stomach. The type and distribution of these lesions are generally similar among family members.
Generalized capillary fragility, as evidenced by spontaneous bleeding, petechiae, ecchymoses, and spider hemangiomas of varying sizes, may exist without overt telangiectasia. Rarely, vascular malformation may cause pulmonary arteriovenous fistulas; then, shunting of blood through the fistulas may lead to hypoxemia, recurring cerebral embolism, brain abscess, and clubbing of digits.
Diagnosis
Diagnosis is based principally on an established familial pattern of bleeding disorders and on clinical evidence of telangiectasia and hemorrhage. Bone marrow aspiration demonstrating depleted iron stores confirms secondary iron deficiency anemia. Hypochromic, microcytic anemia is common; abnormal platelet function may also be found. Coagulation tests are essentially irrelevant, however, because hemorrhage in telangiectasia results from weakness in the vascular wall.
Treatment
Supportive therapy includes blood transfusions for acute hemorrhage and supplemental iron administration to replace iron lost in repeated mucosal bleeding. Ancillary treatments consist of applying pressure and topical hemostatic agents to bleeding sites, cauterizing bleeding sites not readily accessible, and protecting the patient from trauma and unnecessary bleeding. An interventional radiologist may clot off large collections of abnormal blood vessels in the lungs, called arteriovenous malformations, by using a coiling procedure.
Parenteral administration of supplemental iron enhances absorption to maintain adequate iron stores and prevents gastric irritation. Administering antipyretics or antihistamines before blood transfusions, and using saline-washed cells, frozen blood, or other types of leukocyte-poor blood instead of whole blood may prevent febrile transfusion reactions.
The administration of estrogen has proved effective in some patients, especially when used to control epistaxis.
Special considerations
❑ During the first 15 minutes of a blood transfusion, stay with the patient to observe for adverse reactions. Afterward, check again every 15 minutes for signs and symptoms of a febrile or an allergic transfusion reaction (flushing, shaking chills, fever, headache, rash, tachycardia, and hypertension) because patients with this disorder are quite susceptible to this type of reaction.
❑ Observe the patient for indications of GI bleeding, such as hematemesis and melena. Instruct him to watch for and report such signs as well.
❑ If the patient requires an iron supplement, stress the importance of following dosage instructions and of taking oral iron with meals to minimize gastric irritation. Warn him that iron turns stools dark green or black and may cause constipation.
❑ Provide emotional and psychological support. Encourage the patient to express concerns he may have about his disease and its treatment. As much as possible, include him in care decisions.
❑ Encourage fluid intake, when possible, if the patient is experiencing a bleeding episode or is hypovolemic. Monitor intake and output.
❑ Provide good skin care and hygiene, and use sterile technique when caring for the patient. Lesions bleed easily, which may result in infection and skin breakdown.
❑ Monitor the patient’s organ function through physical examination and the comparison of laboratory tests to detect renal, hepatic, or respiratory failure.
❑ Teach the patient and his family how to manage minor bleeding episodes, especially recurrent epistaxis, and how to recognize major episodes that necessitate emergency intervention.
❑ Teach the patient and his family about the disease’s hereditary nature. Refer him for genetic counseling, as appropriate, and to the Hereditary Hemorrhagic Telangiectasia Foundation International for support and information.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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