The basic defect of this disease is the disorder of plasma factor viii synthesis. The factor in normal von Willebrand’s plasma is a glycoprotein with a molecular weight of 1 to 2 million and contains both low and high molecular weight components. The low molecular weight component has coagulation activity (C), while the high molecular weight component has factor associated antigen (R Ag) and VW factor (R VWF). These three components have different synthesis sites, genetic sites and patterns of inheritance. C is synthesized by liver, spleen or monocyte and is affected by a variety of factors
How should Von Willebrand disease be treated?
Receptor silver and receptor VWF are synthesized by endothelial cells, megakaryocytes and platelets and are autosomal inherited. Normal plasma has a VWF value of 10 mg/l, and its activity is generated by a series of plasma polymers. The molecular weight of the polymer is about 400,000 ~ 20 million, and it exists in plasma, platelets and subvascular. A slight decrease in plasma VWF concentration or selective loss of high molecular weight polymers may reduce platelet adhesion.
In VWD patients, these two components are missing, or the molecular structure of these two components is abnormal, the physiological activity of the factor VIII polymer is abnormal, and the function of factor VIII: C has a corresponding effect. R Ag contains different low, medium and high molecular weight polymers, which constitute different subtypes of VWD. The receptor silver polymer binds the platelets to the endothelium and maintains normal bleeding times by binding to specific receptors of the platelets. The effects of mitomycin and R VWF on platelets are related to platelet receptors.
What should be done with Von Willlebrand?
C and R Ag also decreased in different degrees in patients with this disease. After the purified preparation was injected with factor, the bleeding time of the patients was shortened in a short time, while the C increased after 6-24. At present, it is believed that normal R properties stabilize carbon, but when R silver is absent, the activity of R carbon is affected. Therefore, the disease may be caused by defects in the polymer part of the factor or in the entire factor complex. More recently, it has been found that the fibrinolytic system of VWD is also defective.
There are genetic variations in VWD clinically. VWD can be classified into several types according to the biochemical properties and functions of the factor R: Ag. Type I is more common, indicating that the amount of R: Ag is insufficient, the content of various polymers is reduced, all the activities of the factors are reduced, but the structure is normal. Type is divided into autosomal recessive or dominant heredity, the former is rare, clinical manifestation is extremely serious. Plasma rAG disappeared or less than 0.1%, injection of dichlorvos did not improve. Type: R Ag content is normal, but r Ag polymer structure is abnormal. Normal or slightly lower C value is autosomal dominant inheritance. These patients lack high and medium molecular weight polymers. There are several subtypes of type I.
1, Do not use drugs that affect hemostasis and blood coagulation
Aspirin, bute, prumecine, dipyriddamole, low molecular weight dextran, prostaglandin E1, etc. Can affect hemostasis and coagulation function, prevent bleeding aggravation.
2, Oral contraceptives
Such as compound norethinnes, can significantly improve the symptoms of menorrhagia and prolonged duration.
3, Fibrinolytic inhibitors
For example, oral administration of 4-5g of 6-amino caproic acid (EACA) every day, every 6 hours, can reduce mucosal bleeding, and is also effective for menorrhagia. Local fibrinolysis is one of the causes of bleeding in many tissues, especially mucous membranes.
4, Replenishment of factor VIII deficiency by injecting fresh blood is an effective hemostatic measure.
C gradually increased within 12-24 days after blood transfusion, which controlled the bleeding tendency. However, platelet aggregation of restoring mycin and rag declined rapidly after transfusion, so the effect of transfusion on these three factors was inconsistent. In severe cases, 30 to 50 U/kg of cryoprecipitate preparation should be added, and injected once every 24 to 48 hours, with good efficacy. Factor concentration preparations lack the polymer associated with the activity of VW factor to correct bleeding defects and are therefore not preferred.
5, 1- deamino-8-D arginine vasopressin
1- deamino-8 -D arginine vasopressin is a synthetic antidiuretic hormone. The activity of factor viii in plasma increased obviously after intravenous injection. It is used to treat mild, moderate or severe cases, but is not effective in severe cases. The intravenous injection dose was 0.3-0.5 g/kg, dissolved in 20-30 ml normal saline. Because it activates the fibrinolytic system, it binds to tranexamic acid and EACA. The levels of factors (: C and R: Ag) can be increased by 2 ~ 3 times, and reach the peak in 30 ~ 60 minutes after injection, which can prevent local nosebleed and small operation bleeding such as tooth extraction. To maintain the concentration of the factor, the dose was 0.25 ml (1,300 micrograms per ml) twice daily every 8 to 12 hours for the first 2 to 4 days. Side effects include temporary facial flushing and fluid retention.
In principle, surgery should be avoided and new blood, plasma or factor concentrate should be injected before and after surgery to replace the missing factors.