Management of children with von Willebrand disease undergoing adenotonsillectomy

PURPOSE

Children with von Willebrand disease (vWD) are at greater risk for hemorrhage following adenotonsillar surgery. We report the favorable results of 12 consecutive adenotonsillar procedures performed since 1989 in children with vWD, with minimal use of blood products.

MATERIALS AND METHODS

Patients were prospectively managed with careful local control, desmopressin (DDAVP), and antifibrinolytic agents. Cryoprecipitate or intermediate purity factor VIII concentrates containing von Willebrand factor (vWF) were used for three patients who did not tolerate DDAVP.

RESULTS

Based on this experience, we propose a prospective treatment protocol.

CONCLUSIONS

The literature regarding the use of DDAVP is reviewed, and our screening algorithm and treatment protocol for managing these challenging cases is presented.

Thrombotic thrombocytopenia induced in dogs and pigs. The role of plasma and platelet vWF in animal models of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenia with severe depletion of plasma von Willebrand factor (vWF) was induced in normal large animals (5 dogs and 2 pigs) by botrocetin, a Bothrops factor requiring vWF for platelet agglutination. Botrocetin (90 to 100 U/kg, 2.14 to 2.38 mg/kg, in a single i.v. injection) reduced plasma vWF activity to < 0.1 U/mL for 24 hours. During this period, multimeric analysis of plasma vWF antigen (Ag) revealed the loss of intermediate- and high-molecular-weight forms with a concomitant increase in lower molecular weight forms. A moderate reduction in factor VIII (FVIII) activity was observed. The vWF reduction was accompanied by transient thrombocytopenia and prolonged bleeding times during the deficiency state. Occlusive platelet thrombi were detected by transmission electron microscopy in the microcirculation of lung and spleen but not kidney or brain 30 minutes after the botrocetin injection. Recovery of plasma vWF and platelet count occurred within 48 hours and was associated with the appearance in the plasma of unusually large forms of vWF:Ag multimers. The vWF:Ag multimer distribution was normal at 72 hours. The ultrastructural distribution of vWF in unstimulated normal porcine and canine platelets was examined by using immunogold staining. VWF was detected in the alpha-granules of normal pig platelets but was not observed in platelets from normal dogs. However, both animals developed thrombotic thrombocytopenia when injected with botrocetin. A second group of animals (2 dogs and 3 pigs) with von Willebrand disease (vWD) was given a single botrocetin injection (90 to 100 U/kg). No thrombocytopenia occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Recent advances in the management of patients with haemophilia and other bleeding disorders

Much attention has been focused recently on barriers to dental care, particularly for patients with disabilities, from the perspective of the patient and the dental team. Treatment of patients with haemorrhagic disorders may cause a certain amount of anxiety in dental staff. The authors of this paper aim to reduce this anxiety by clarifying confusion between the haemorrhagic disorders and making recommendations concerning the dental care of such patients.

Blood product use by hemophiliacs in relation to AIDS risk awareness and patient variables

Although some hemophiliacs in other studies have reported restricting blood product use because of fear of possible transmission of the human immunodeficiency virus (HIV), no overall change in the quantity of blood products infused between January 1981 through December 1985 was found in a sample of 40 hemophiliacs before or after they became aware of the risk of contracting the acquired immunodeficiency syndrome (AIDS). However, there was a significant linear increase in blood product use with time during the period of AIDS risk awareness. This may be a nonspecific, chance finding; or it may reflect an increase in spontaneous bleeds secondary to AIDS-related stress. The implications of these findings are discussed, and specific areas for future research are recommended.

[Multimeric composition of von Willebrand factor in thrombotic thrombocytopenic purpura. Japanese TTP Study Group]

Thrombotic thrombocytopenic purpura (TTP) is an uncommon disorder. Several hypotheses have been reported up to now but, the pathogenesis is not yet clear. On the other hand, von Willebrand factor (vWf) plays a role in platelet agglutination in initial hemostasis. Moake and other investigators suggested plasma vWf abnormalities. In this paper, we analysed vWf antigen, ristocetin cofactor (RCof) and multimeric composition of vWf in 16 patients with TTP. It was found that vWf antigen and RCof ranged from very low to very high levels, but RCof was lower than vWf antigen except in two cases. Decrease of large multimer of vWf was seen in 11 patients (69%). These abnormalities were corrected at remission by therapy.

Emergency dental management of a patient with von Willebrand's disease

A patient with von Willebrand's disease presenting for dental treatment requires thorough evaluation prior to the determination of a proper course of treatment. In this case report, a patient with von Willebrand's disease presented to the emergency room with dental trauma. A modified treatment plan, taking into account the severity of the patient's systemic illness and the need for medical management, yielded successful results.

Haemostasis in oral surgery--the possible pathogenetic implications of oral fibrinolysis on bleeding. Experimental and clinical studies of the haemostatic balance in the oral cavity, with particular reference to patients with acquired and congenital defects of the coagulation system

Activation and inhibition of the haemostatic system was reviewed including the interaction between the four biological systems involved in haemostasis: the vessel wall, the platelets, the coagulation system and the fibrinolytic system. The haemostatic mechanism is initiated at the site of injury through local activation of surfaces and release of tissue thromboplastin, resulting in formation and deposition of fibrin. The coagulation process is regulated by physiological anticoagulants. Activation of fibrinolysis is triggered by the presence of fibrin, and the role of tissue-type plasminogen activators (t-PA) at the site of fibrin formation in particular is emphasized. The process is regulated by physiological inhibitors, of which alpha 2-antiplasmin, histidine-rich glycoprotein and plasminogen activator inhibitor are reported to be of major physiological significance. The role of fibrinolysis in the regulation of the dynamic haemostatic balance is discussed, elucidated through examples of congenital deficiencies of the coagulation and the fibrinoytic system. Pharmacological inhibitors of fibrinolysis (i.e. epsilon-aminocaproic acid and tranexamic acid) and their possible effect on the haemostatic system are described. The systemic effects on the fibrinolytic system of surgery and oral surgery is reviewed, and it is concluded, that oral surgery has insignificant effects on blood fibrinolysis. In contrast, oral surgery induces changes of fibrinolysis in the oral environment; initially the fibrinolytic activity of saliva is reduced, due to the presence of inhibitors of fibrinolysis originating from the blood and the wound exudate. When bleeding and exudation cease, the fibrinolytic activity of the saliva will increase. Plasminogen and plasminogen activator, identified as t-PA are present in the oral environment under physiological conditions. Plasminogen is secreted in the saliva and the sources of t-PA include oral epithelial cells and gingival crevicular fluid. The presence of plasminogen and t-PA in the oral environment implies that when fibrin is present (i.e. after surgery), fibrinolysis is triggered. Haemorrhagic complications to oral surgery in patients without known defects of the coagulation system is reviewed. It is concluded that the investigations conducted to the present day do not permit final conclusions with respect to the pathophysiological role of defects in the coagulation and the fibrinolytic systems for the development of bleeding after oral surgery. Further investigations are necessary in order to clarify these aspects, and should include extensive laboratory analyses to reveal rare congenital defects such as factor XIII- and alpha 2-antiplasmin deficiencies.(ABSTRACT TRUNCATED AT 400 WORDS)

Oral management of patients with bleeding disorders. Part 1: Medical considerations

An overview of hemostasis, the pathophysiology of bleeding disorders, with a description of clinical features, and recent advances in treatment are presented. This paper is the first of a series of two discussing the management of patients with bleeding disorders in preparation for various dental procedures.

[Prophylactic use of DDAVP in a patient with von Willebrand disease during labor: a case report and a review]

A Case of delivery in a 23-year-old woman after a prophylactic infusion of DDAVP is described. She had a life-long history of easy bruising and frequent epistaxis, with the diagnosis of vWD being made when she was 14 years old. A hemostatic examination showed a prolonged bleeding time, a moderate reduction in the factor VIII level (VIII: C) and von Willebrand Factor Antigen (vWF: Ag), decreased platelet aggregation by ristocetin, and depletion of platelet retention. In April, 1988, in the 34th week of pregnancy, she was admitted to our clinic in order to avoid abnormal bleeding during labor. On admission, the level of factor VIII, ristocetin aggregation, and platelet retention were normal, but the bleeding time remained prolonged. The diagnosis of vWD type I was made on the normal multimeric structure. The DDAVP infusion test revealed a shortening of the bleeding time and an increase in the vWF: Ag. In the 41st week of pregnancy, labor was induced, accompanied by infusion of DDAVP, she gave birth to an infant without any abnormal bleeding. Since conventional treatments with human plasma derivatives may cause complicating viral infections, we propose the infusion of DDAVP is one of the treatments to prevent the abnormal bleeding of the patient with vWD during labor.

[Local treatment of Von Willebrand's disease--use of GRF adhesive]

Among the systemic hemorrhagic we find Von Willebrand's, the most prevalent coagulation related illness. It may be defined as a qualitative platelet abnormality which in most cases is transmitted as a dominant mendelian trait. Clinically there is prolonged bleeding time, epistaxis, gingival hemorrhage and increased bleeding after surgery or dental extractions. The purpose of this project was to test the effectivity of a local element such as GRF glue as the only treatment for these patients. With the purpose to avoid the use of a substitute therapy, mainly taking into consideration all the problems derived from the AIDS virus. It was concluded that GRF glue was an excellent local treatment for Von Willebrand's carries with factor VIII over 10%. Systemic therapy must be instituted in patients under the 10% circulating factor VIII.

Prostatectomy in patients with bleeding disorders

Urological surgery is becoming increasingly necessary in patients with acquired or congenital bleeding disorders. We reviewed the management of 10 such patients who required prostatectomy. The average age of the patients at operation was 65.7 years. Seven patients underwent transurethral prostatectomy and 3 underwent suprapubic prostatectomy. Postoperative bleeding occurred in 9 patients who required secondary procedures. Bleeding occurred an average of 13 days postoperatively. The mean hospital stay was 24 days. Partial thromboplastin time when determined was uniformly elevated in all patients preoperatively. The amount of factor and blood replacement is presented. Perioperative management of these patients is discussed in detail. A rational approach for the prevention of postoperative bleeding is presented.

Von Willebrand's disease in pregnancy. A case report

A 30-year-old woman with von Willebrand's disease completed her third pregnancy uneventfully. She was infused during labour with fresh frozen plasma and cryoprecipitate. This is in keeping with the good outcome reported in the literature when management is appropriate and surveillance is maintained.

Von Willebrand's disease in pigs and atherosclerosis

There is experimental evidence that platelets, by interacting with the arterial wall may be important in the initiation of atherosclerosis. This paper describes the results of consecutive experiments indicating that pigs with impaired platelet-blood vessel interaction in the form of von Willebrand's disease are resistant to the development of atherosclerotic plaques. Ongoing experiments in these pigs are providing significant insight into the relationship of the circulating platelets, the endothelial cell and circulating von Willebrand factor, and the reactivity of the arterial wall in the process of atherosclerosis.