Platelet function and immunologic parameters in von Willebrand's disease following cryoprecipitate and factor VIII concentrate infusion

Efficacy of fresh-frozen plasma and cryoprecipitate in dogs with von Willebrand's disease or hemophilia A

Here we report the comparative efficacy of fresh-frozen plasma (FFP) and cryoprecipitate in the treatment of 2 inherited bleeding disorders in dogs. The dogs were divided into 3 groups, consisting of 4 Doberman Pinschers with type I von Willebrand's disease (vWD) (group 1), 1 Scottish Terrier with type III vWD (group 2), and 4 German Shepherd Dogs with hemophilia A (group 3). In vWD, therapeutic efficacy was determined by the ability of the products to increase von Willebrand factor antigen (vWf:Ag) concentrations above 35 canine units (CU)/dL and to correct the prolonged buccal mucosal bleeding time. Therapeutic efficacy in hemophilia A was assessed by the ability of the products to increase the factor VIII coagulant (FVIII:C) activity above 30 CU/dL. In both groups 1 and 2, higher increases in vWf:Ag were achieved with cryoprecipitate than with FFP, despite a significantly smaller total amount of vWf:Ag (in CU) being infused with cryoprecipitate. The maximum vWf:Ag attained after infusion in group 1 was dependent on both the baseline vWf:Ag concentration and on the type of infusion product. The dogs with vWD in both groups also displayed a delayed increase in FVIII:C activity after infusion of both plasma products, which is characteristic of the disease. In group 3, cryoprecipitate achieved similar increases in FVIII:C activity compared to FFP, although a significantly lesser amount of FVIII:C (in CU) was delivered with cryoprecipitate. Six of the 9 dogs treated with FFP experienced adverse effects ranging from mild pruritus to pallor and weakness, whereas none of the 9 dogs treated with cryoprecipitate had any observable adverse reactions (P = .009). Based on its efficacy and safety, we recommend cryoprecipitate over FFP for treatment or prophylaxis of hemorrhagic episodes in dogs with vWD or hemophilia A.

Replacement therapy with virus-inactivated plasma concentrates in von Willebrand disease

In von Willebrand disease, the goal of treatment is to correct the two laboratory hallmarks of abnormal hemostasis, i.e. the deficiency of factor VIII (FVIII) and the prolonged bleeding time (BT). Since desmopressin (DDAVP) is able to achieve both these goals in the majority of patients, it is the treatment of choice. Some patients, however, are not responsive or become refractory to DDAVP. In these, blood products maintain an important therapeutic role, and there is a need to assess the efficacy of the recently available virus-inactivated plasma concentrates, which contain both FVIII and von Willebrand factor and carry a low risk of transmitting blood-borne viruses. Our survey of the data reported in the literature indicates that all available concentrates are similarly effective in attaining high and sustained levels of FVIII after infusion. Although they often shorten or normalize the prolonged BT, that effect is less uniform. Since concentrates appear efficacious in the majority of clinical situations that require the use of blood products, they should be preferred, because of their greater safety, to cryoprecipitate produced by blood banks, which cannot be virus inactivated.

Management of intraventricular haemorrhage secondary to ruptured arteriovenous malformation in a child with von Willebrand's disease

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Studies on the prolonged bleeding time in von Willebrand's disease

Ten studies of the effect of cryoprecipitate infusion in four patients with von Willebrand's Disease (vWD) are reported. The doses studied (4, 8 and in one case 10 bags of cryoprecipitate) were based on previous reports of correction of the bleeding time (BT) with such doses. A modest shortening of the BT was observed in only 2 studies and complete correction of the BT at 1 and 4 hours was observed in only one study. This latter result could not be reproduced in a subsequent study of the same patient. In all cases, the von Willebrand factor antigen (vWF:Ag) multimer patterns were normal in the infused cryoprecipitate and in the recipients' plasma post infusion with the presence of high molecular weight multimers demonstrated in all samples. These results contradict earlier reports of the effect on the BT of similar doses of cryoprecipitate and suggest that the presence of the high molecular weight forms of vWF:Ag does not necessarily correlate with the presence of the factor which corrects the bleeding time.

Correction of the bleeding time in treated patients with severe von Willebrand disease is not solely dependent on the normal multimeric structure of plasma von Willebrand factor

Even though it is generally held that cryoprecipitate and fraction I-O correct the prolonged bleeding time (BT) in patients with von Willebrand disease (VWD), perusal of reported data indicates that the correction is usually short-lasting and often partial. We decided to do a controlled study of the relationship between the multimeric structure of von Willebrand factor (VWF) and the BT in five patients with severe (type III) VWD after infusion of three plasma concentrates ("wet" cryoprecipitate, lyophilized cryoprecipitate, and fraction I-O) given in random order. The dosage of concentrates was tailored from in vitro measurements to achieve post-infusion levels of ristocetin cofactor above the lower normal limit (50 U/dL) for at least 3 hours. The postinfusion BT became transiently normal in only two of five patients treated with wet cryoprecipitate, whereas it remained prolonged in all five patients treated with lyophilized cryoprecipitate or fraction I-O. For all the concentrates, the proportion of large VWF multimers calculated by scanning the electrophoretic gels were the same as those for normal standard plasmas. An intact multimeric structure was recovered in postinfusion plasmas of patients treated with wet cryoprecipitate, whereas there was a postinfusion loss of large multimers after lyophilized cryoprecipitate and fraction I-O. These findings indicate that the attainment of a normal BT is the exception rather than the rule after the infusion of three plasma fractions used in the treatment of severe VWD, and that an intact multimeric structure in concentrates and postinfusion plasmas is necessary but not sufficient to sustain a normal BT.

von Willebrand's disease prevents occlusive thrombosis in stenosed and injured porcine coronary arteries

We studied the role of von Willebrand factor in coronary thrombosis in normal, heterozygous, and homozygous von Willebrand's disease pigs by producing coronary stenosis with a Goldblatt clamp positioned around the left anterior descending coronary artery. Flow velocity was assessed by a 20-MHz Doppler velocity probe distal to the Goldblatt clamp. Myocardial extracellular potassium levels were measured by potassium-sensitive electrodes in myocardium supplied by the left anterior descending artery. Whereas stenosis sufficient to block reactive hyperemia to a 20-second occlusion produced an elevation of myocardial extracellular potassium, it produced neither spontaneous cyclic flow reductions nor permanent cessation of coronary blood flow velocity. Injury of the coronary artery at the stenosis site with spring-loaded forceps produced cyclic flow reductions or permanent cessation of flow in eight of nine phenotypically normal pigs. On the other hand, flow variations occurred in none of the 10 von Willebrand's disease pigs, including four given purified von Willebrand factor at a dose that failed to correct the bleeding time (p less than 0.001, chi 2 test). Permanent cessation of flow was caused by an occlusive platelet-fibrin-red-blood-cell thrombus. Scanning electron micrographs from pigs with cyclic flow variations and from von Willebrand's disease pigs showed injured endothelium covered by adherent platelets, red and white blood cells, and fibrin. These data suggest an important role of native von Willebrand factor in sudden occlusive arterial thrombosis following stenosis and intimal injury.

Replacement therapy in platelet-type von Willebrand disease

The response to infusions of cryoprecipitate and factor VIII concentrate was studied in a patient with platelet-type von Willebrand disease (vWD) who showed lack of the large multimers of von Willebrand factor in plasma, increased platelet aggregation with low concentrations of ristocetin, and in vitro platelet aggregation by normal plasma. The cryoprecipitate and factor VIII concentrate to be infused induced platelet aggregation when added to patient platelet-rich plasma at concentrations higher than 0.86 U/ml and 3 U/ml of factor VIII-related antigen (VIIIR:Ag), respectively. Administration of cryoprecipitate (41.9 U VIIIR:Ag/kg body weight) was followed by a shortening of the bleeding time, and hemostasis was achieved during tooth extractions. Factor VIII concentrate (70.2 U VIIIR:Ag/kg) failed to correct the prolonged bleeding time and proved ineffective to control the gum bleeding. No significant diminution of the platelet count was observed following any infusion. These results indicate that cryoprecipitate is hemostatically effective and safe when infused in such a dosage, but factor VIII concentrate is not effective in platelet-type vWD in analogy to what is observed in various types of vWD.

The use of heat-treated Factor VIII-concentrates in von Willebrand's disease

In vitro investigations have demonstrated a high F VIII:Rcof potency and a high F VIII:Rcof/F VIII R:Ag ratio of two heat-treated F VIII concentrates. We therefore studied the in vivo effectiveness of these preparations (F VIII HSR, Behringwerke Marburg and F VIII HTR, Travenol) in five patients with von Willebrand's disease (vWd). In the steady state in vivo recoveries of F VIII:Rcof ranged from 73-153% after transfusion of F VIII HSR and from 11.5-17% after F VIII HTR respectively. The gain of F VIII-complex after F VIII HS was comparable to cryopecipitate (KryobulinR SP, Immuno AG Wien). All three products shortened the bleeding-time. Three of our five patients underwent surgery (Billroth I, papillotomy, laparatomy, open heart surgery) under F VIII HS cover without bleeding complications. The dose applied ranged from 20 to 40 U/kg at 8 or 12 h intervals for a period of approx. 14 days. Serum-transaminase elevations were observed in two of four patients after F VIII HT treatment. Although the risk of hepatitis of heat-treated F VIII concentrates remains to be determined, these products proved to be effective in vWd. The major advantages of these preparations are stability, rapid solubility, a low content of contaminating proteins, and a rapid, general availability.

Preparation of pooled cryoprecipitate for treatment of hemophilia A in a home care program

Cryoprecipitate is used infrequently in home therapy for patients with hemophilia A since freezer storage is required and resuspension and pooling of thawed cryoprecipitate is cumbersome. We evaluated procedures for preparation of cryoprecipitate in an "open system" so that four to six bags of cryoprecipitate could be pooled after production and refrozen for home therapy. Factor VIII activity for pooled cryoprecipitate was 132 +/- 30 (mean +/- SD), 125 +/- 45, and 145 +/- 47 units per bag pooled in three separate studies. Cultures from cryoprecipitate pools and individual cryoprecipitate bags did not show contamination in the "open system" or with the water bath thawing procedure. The mean increment in factor VIII activity per unit per kg infused was 0.02 units per ml and the mean half-life was 10.5 hours in three patients with hemophilia A. Pooled cryoprecipitate was shown to be clinically efficacious and acceptable for use in home care programs for hemophilia A.

Purification of the factor VIII complex

Two high purity factor VIII concentrates, type I and type II were developed for clinical trials in patients with hemophilia A and von Willebrand's disease. Fresh frozen plasma containing 1% polyethylene glycol 4000 was thawed to form cryoprecipitate, which was subsequently dissolved in citrate buffer. By addition of glycine buffer to a final concentration of 2.0 M at 26 degrees C, the bulk of fibrinogen was precipitated while factor VIII remained in solution. Factor VIII was precipitated from the glycine supernatant by addition of solid sodium chloride. The recovery of factor VIII procoagulant activity (VIII:C) per kg plasma was 271 +/- 23 units (n = 4) and 386 +/- 47 units (n = 7) for the type I and the type II preparations, respectively, while the recovery of von Willebrand factor related activity (ristocetin cofactor, VIIIR:RC) was 518 +/- 75 units and 718 +/- 90 units per kg plasma, respectively. The specific activity (units per mg protein) of VIII:C in the type I and type II preparations were 2.53 +/- 1.02 and 7.56 +/- 1.33, respectively. The specific activity (units per mg protein) of VIIIR:RC for the type I and type II preparations were 4.86 +/- 2.32 and 13.6 +/- 3.7, respectively. VIIIR:Ag was present as multimers in both preparations, and the multimeric pattern was similar to that of normal plasma. The preparations have the ability to correct the prolonged bleeding time in severe von Willebrand's disease. The factor VIII complex in the type II preparations was further purified by gel filtration on Sephacryl S-1000. This preparation was free of fibrinogen and fibronectin. Its specific activity in terms of VIII:C was 47 u/mg protein and 104 u/mg protein in terms of VIIIR:RC. The subunit of reduced factor VIIIR:Ag had Mr of 210 Kd on sodium dodecyl sulfate polyacrylamide gel electrophoresis.

An in vivo study of a new factor VIII high purity preparation

The efficacy of high purity preparations of factor VIII complex are usually lacking effect on the bleeding time in von Willebrand's disease. In this report we have studied the efficacy of a new high purity factor VIII preparation in two von Willebrand and two hemophilia A patients. The prolonged bleeding time in the patients with von Willebrand's disease was corrected after infusion of the preparation and a secondary rise in factor VIII procoagulant activity (VIII:C) demonstrated. The biological half-life time of VIII:C, in the two hemophilia A patients, was about 15 hrs. The investigation shows that this particular preparation is capable of correcting the prolonged bleeding time in von Willebrand's disease.

Von Willebrand Factor (VIIIVWF) in lyophilized Factor VIII concentrates

Several (14) commercially prepared, lyophilized Factor VIII concentrates were assayed for VIIIAHF, VIIIAg, and VIIIVWF. Significant levels of VIIIAg (immunologic) and VIIIVWF (von Willebrand Factor) were present in addition to VIIIAHF (Functional VIII, Antihemophilic Factor, Factor VIII coagulant activity). An average of 0.95 units of VIIIVWF (range 0.47--1.7) were present for every 1.0 unit of VIIIAHF (as stated on the manufacturer's label). We suggest that the various lyophilized preparations of Factor VIII concentrate available could be assayed for VIIIVWF and should be tested therapeutically in patients with von Willebrand disease.

Von Willebrand's disease

Von Willebrand's disease is an autosomally transmitted disorder of hemostasis caused by a deficiency of or defect in the von Willebrand factor in the blood, a protein required for adherence of platelets to an injured vessel wall. The disease's principal manifestations are spontaneous bleeding from mucous membranes, excessive bleeding from wounds, and menorrhagia. The major laboratory abnormality in prolongation of the skin bleeding time, with reduced platelet retention by glass bead columns, impaired platelet agglutination by ristocetin, and reduced factor VIII--related antigen and factor VIII coagulant activity as associated defects. Recommended therapy is infusion of plasma cryoprecipitate, which briefly corrects bleeding time and normalizes the disorder's other manifestations.

In vitro and in vivo characterization of factor VIII preparations

An in vitro and in vivo comparison of nine commercial and noncommercial factor VIII preparations was made. These consisted of one lyophilized cryoprecipitate, four intermediate (IPC) and four high purity concentrates (HPC). Protein, fibrinogen, factor VIII complex, IgG, IgM and anti-A and B alloagglutinins levels were measured. These three qualities of product were defined by two ratios: units of F VIII:C per mg of protein and per mg of fibrinogen. They were, respectively, less than 0.05 and less than 1 in cryoprecipitate, 0.5--1 and 1--3 in IPC, and greater than 1 and greater than 3 in HPC. The F VIII:C/F VIII:AG ration ranged from 0.3 to 0.6 and the F VIII:C/F VIII:VWF ratio was always lower than 1. Varying titers of alloagglutinins were found, unrelated to either IgG or IgM levels. Seven of these preparations were injected into several classical hemophilia A patients for treatment of minor hemorrhages. The peak of F VIII:C activity was always found 1 h postinjection. The F VIII:C recovery ranged from 80 to 140% and the half-life from 8 to 15 h. No significant difference was found among these products and the clinical efficacy was similar.

Acquired von Willebrand's syndrome with IgM inhibitor against von Willebrand's factor

This report describes a patient without evident underlying disease, in whom an acquired von Willebrand's syndrome was discovered before surgery. Coagulation abnormalities included a borderline bleeding time, a low retention of platelets on glass beads, decreased levels of factor VIII procoagulant activity (VIIIAHF), factor VIII-related antigen (VIIIAg), and ristocetin-induced agglutination cofactor (VIIIVWF). After cryoprecipitate infusion the patient did not have the expected rise and there was no secondary increment in VIIIAHF. The patient was treated with prednisone for three weeks without significant improvement in the laboratory findings. Spontaneous resolution was observed long after this therapy. The haemostatic abnormalities were attributable to the presence of an inhibitor directed against VIIIVWF. The inhibitor was found in the IgM fraction. Its autoimmune nature is probable although we failed to demonstrate any inhibitory effect of Fab obtained from the patient's purified IgM. Despite the lack of inhibitory effect against VIIIAHF and VIIIAg, the low levels of all three activities of the factor VIII complex could be explained by the short half-life of immune complexes between factor VIII and the inhibitor.

Cycles of agglutination-disagglutination induced by ristocetin in thrombasthenic platelets

An oscillatory pattern of platelet agglutination-disagglutination in response to Ristocetin (R) at narrow concentration ranges was observed in citrated platelet rich plasma (PRP) of 10 patients with Glanzmann's thrombasthenia. The cyclic pattern decreased in intensity over time, was reproducible, and was not pH dependent. Formalin-fixed thrombasthenic platelets agglutinated with R but did not show a cyclic pattern. Incubation with 2.5 microM ADP inhibited R oscillation response, but small increases in R dose overcame this inhibition. The addition of ATP or creatine phosphate/creatine phosphokinase to thrombasthenic platelets inhibited by ADP restored the R oscillation response. In the platelets of a single patient, intracellular levels of ADP and ATP were shown to diminish during an oscillation response to R. There was an increase in AMP levels during the same period of time. The changes in these three intracellular nucleotides were gradual over time and did not vary with phases of the oscillation. Acetyl salicylic acid (ASA), at concentrations shown to block cyclooxygenase activity in control platelets, enabled thrombasthenic platelets to respond to R with full agglutination without oscillations. Lower concentrations of ASA in the PRP gave a return of the oscillation response. Our data suggest that the disagglutination phase of the R response of thrombasthenic platelets is not a function of the known glycoprotein membrane defect, but depends on materials originating in the platelet whose release is blocked by ASA.

Aortic valve replacement in a patient with von Willebrand's disease

Few cases have been reported to date of cardiac surgery performed on patients with von Willebrand's disease. This report details the management of such a patient, who underwent aortic valve replacement for severe calcific aortic stenosis.

Classification of von Willebrand's disease

The classification of von Willebrand's disease should be based primarily on the mode of inheritance: thus, the main division would between autosomal dominant and autosomal recessive types. Phenotypic subdivisions within these major types may then be possible. A subgroup of the dominant type seems to be well defined by increased electrophoretic mobility of the VIII-related antigen.

Acquired von Willebrand's disease, platelet-release defect and angiodysplasia

A previously healthy elderly man with gastrointestinal bleeding was found to have criteria for von Willebrand's disease. The late clinical onset of the disorder and negative family studies suggest that the von Willebrand's disease may be acquired. The findings in the patient were similar to the abnormalities reported in the small number of other patients thought to have acquired von Willebrands disease. An inhibitor of factor VIII could not be demonstrated in this patient. This patient also had platelet aggregation abnormalities that are atypical for patients with congenital or acquired von Willebrand's disease. Vascular abnormalities were also found in this patient and in several other previously described patients with von Willebrand's disease.