Prothrombin and accessory factors; clinical significance

Is prophylaxis required for delivery in women with factor VII deficiency?

Factor VII (fVII) deficiency is a rare congenital bleeding disorder in which fVII activity level and bleeding tendency do not completely correlate. Pregnancy and delivery present a significant haemostatic challenge to women with fVII deficiency. Treatment with recombinant factor VIIa (rfVIIa) carries a thrombotic risk and the literature is not clear whether prophylaxis is necessary prior to delivery. The aim of this study was to define management, haemorrhagic and thrombotic complications of pregnant women with fVII deficiency through a systematic review. Medical databases (PubMed, MEDLINE, CINAHL, Academic Search Premier, Cochrane Library, Web of Science and Scopus) were searched using "factor VII deficiency" and "pregnancy" or "surgery." Overall 34 articles, four abstracts, and three institutional cases were reviewed. Literature from 1953 to 2011 reported 94 live births from 62 women with fVII deficiency. The median fVII activity was 5.5%. Haemostatic prophylaxis was used in 32% of deliveries. Without prophylaxis, 40 vaginal deliveries and 16 caesarean sections were completed. The odds of receiving prophylaxis were 2.9 times higher in women undergoing caesarean section compared to vaginal delivery. Post-partum haemorrhage occurred in 10% of deliveries with prophylaxis and 13% of deliveries without prophylaxis. The fVII level did not significantly differ between women who did and did not receive prophylaxis. We present the only systematic review of the management of pregnancy in fVII deficient women. No difference in post-partum haemorrhage was seen in deliveries with and without prophylaxis. Therefore, we recommend that rfVIIa be available in the case of haemorrhage or surgical intervention, but not as mandatory prophylaxis.

Pregnancy and oral contraceptives in congenital bleeding disorders of the vitamin K-dependent coagulation factors

Pregnancies and deliveries represent important hemostatic challenges for congenital coagulation disorders. The same is true for the assumption of oral contraceptives. Available information mainly deals with von Willebrand's disease, factor XI (FXI) deficiency and carriers of hemophilia A. Data concerning patients with congenital prothrombin complex factor deficiencies are very scanty. In the present study, data of a total of 27 women are presented, 11 patients with homozygous or double heterozygous deficiencies of FII, FVII and FX, together with 16 cases of hemophilia B carriers. The patients with FII, FVII or FX defects had a total of 14 pregnancies and often needed transfusion therapy. Proper management resulted in a decrease in postpartum bleeding and satisfactory fetal outcome. Elective cesarean delivery seems indicated only in recent years. Carriers of hemophilia B had a total of 19 pregnancies but showed no bleeding and needed no substitutive therapy. Searching the literature, we discovered only 9 additional patients with prothrombin deficiency or FX deficiency, having a total of 16 pregnancies. On the contrary, there were at least 17 additional patients with FVII deficiency, with a total of 21 pregnancies. The management of the diseases has been variable, but in substantial agreement with the personal observations. Oral contraceptive therapy was administered in some of our patients and in a few additional cases described in the literature. Medication was always well tolerated and patients who took it for a long period of time showed a decrease in menometrorrhagia and an improvement in hematocrit levels. This led to a decrease in transfusional needs and to improved general conditions.

Dietary fatty acids and the haemostatic system

Studies of the effects of dietary fatty acids on the haemostatic system, and their potential relevance for the thrombotic component of coronary heart disease (CHD), have a pedigree as long as those linking dietary fat, plasma lipoprotein metabolism and atheroma. Achievements have not been as impressive, however, partly owing to the relatively slow evolution of our understanding of the complicated physiology, biochemistry and pathology of haemostasis and fibrinolysis, which remains incomplete. Progress was also retarded up to 1980 by a general reluctance to acknowledge the pathogenic importance of thrombosis for myocardial infarction. Interest in dietary fat and the haemostatic mechanism re-emerged with reports of associations of haemostatic variables with plasma triacylglycerol levels and risk of CHD. This review summarises the history, focuses on evidence for dietary C18-unsaturated fatty acids as important determinants of factor VII (FVII) activation and plasminogen activator inhibitor type 1 (PAI-1) levels, and discusses possible underlying mechanisms involving ATP binding cassette (ABC) transporters and peroxisome proliferator-activated receptors. The potential relevance of these effects for CHD is discussed. In the presence of unstable atheromatous plaques, increased levels of activated FVII and PAI-1 induced by diets rich in mixtures of saturated and unsaturated fats may raise the risk of occlusive thrombosis in the event of plaque rupture.

Factor VII deficiency

This report describes three patients with factor (F) VII deficiency: two adult siblings and an unrelated 5 1/2-month-old child who succumbed after several central nervous system (CNS) hemorrhages. This event prompted a review of the literature concerning the incidence and characteristics of intracranial hemorrhage in congenital F VII deficiency. Of 138 patients reported to have F VII deficiency, only 75 were considered to have a true deficiency. There was a 1:1 sex distribution with a 19% incidence of consanguinity in the 63 families which these 75 patients represented. CNS hemorrhage occurred in 12 of the 75 proven factor-deficient patients -- an incidence of 16.0%. There was a 1.4:1 female predominance in this group with a 44.4% incidence of consanguinity in their nine families. Except for one patient with hypertension, there was no history of preceding trauma or previous underlying CNS abnormality, though head trauma with a difficult vaginal delivery may have occurred in five infants. Diagnostic lumbar puncture or ventricular tap revealed bloody, xanthochromic cerebrospinal fluid in five. Five patients with F VII deficiency developed a CNS hemorrhage prior to 1 week of age, and none survived. Seven patients older than 1 week of age suffered such an event, and four of these survived. It is concluded that the greatest risk factor for development of CNS hemorrhage is trauma related to the birth process.

Proteolysis, Fibrinolysis, and Coagulation

The fibrinolytic mechanism, one of the blood protease systems, constitutes a fourth phase of clotting, which contributes to maintenance of coagulation in delicate balance.

"Shwartzman"-induced in vivo coagulation, combined with fibrinolysin, produces profound clotting defects with severe hemostatic failure, in contrast to the relative innocuousness of either alone.

The same defects are obtainable in vitro. The thrombin-fibrinogen interaction is blocked, simulating the in vivo "afiibrinogenemia." These observations are pertinent to thrombolytic therapy invoked for conditions where intravascular clotting may be occurring.

Fibrinogen clottability is also blocked by trypsin. Apparently, fibrinolysin, thrombin, and trypsin are competitive for fibrinogen.

Trypsin, as, well as other proteases, markedly activates factors II, VII, and X, resembling the action of thromboplastin. In contrast, fibrinolysin and thrombin are inert on these clotting factors, whereas on factor V they first activate and then destroy it. This explains why factor V depression is observed in thrombolytic therapy.

The activating effect of trypsin on factors II, VII, and X precludes its use in thrombolytic therapy, and also draws attention to the tryptase-antitryptase equilibrium in normal and certain thrombotic states.

The experimental observations help elucidate some clinical and clinicolaboratory findings in acquired "afibrinogenemia" and therapeutically induced "fibrinolytic" states. The retarded thrombin clotting time of the plasma, and reduction in prothrombic activity attributable to fibrinolytic depression of factor V, may be valuable guides to thrombolytic therapy.

Effect of Dicumarol on Blood Vascular Integrity in the Rabbit

Results of experiments in rabbits in which the disappearance of Evans Blue labeled plasma proteins was used as a measure of vascular integrity, indicate that Dicumarol does increase the rate of loss of plasma proteins from the blood stream. This action does not occur immediately after the introduction of Dicumarol into the blood stream but requires a latent period of between 90 and 180 minutes. During this time there may actually be a decreased rate of loss from the blood.

The degree of increase in the dye disappearance rate, although not directly correlated with the degree of hypoprothrombinemia, can be roughly correlated with the extent and severity of internal hemorrhage. These results tend to confirm the idea that vascular fragility, usually considered independent of vascular permeability, may in this instance be the preliminary manifestation of Dicumarol hemorrhagic diathesis.

In experiments where the effect of Dicumarol on exchange of protein between plasma and the peritoneal cavity was measured, it has been found that the presence of vitamin K 1 in the blood in sufficient amount to completely block the hypoprothrombinemic action will also block the tendency toward increased protein exchange. Also, if Dicumarol is introduced into the peritoneal cavity rather than directly into the blood stream, the increase in transperitoneal protein exchange rate appears to be fairly proportional to the degree of hypoprothrombinemia.

It is concluded that although the possibility of several independent actions of Dicumarol exists, one effecting vascular permeability and another inhibiting the elaboration of coagulation factors, it is more likely that the changes seen in vascular integrity are related to the effects of the drug on the coagulation mechanism by way of vitamin K inhibition.

Fibrinolysin (Plasmin) Therapy in Acute Deep Thrombophlebitis

Sixty-two patients with deep thrombophlebitis of less than 10 days' duration were studied in controlled fashion. Thirty "control" patients were treated by routine methods including anticoagulant drugs. Thirty-two "treatment" patients received fibrinolysin (plasmin) in addition to control therapy.

The composition of the groups studied and the protocol followed are presented in detail.

Comparison of the 2 groups indicates that the addition of fibrinolysin to the therapeutic regimen leads to more rapid clearing of the acute phlebitic episode and may diminish the short-term incidence of phlebitic recurrence and pulmonary embolization. Postphlebitic residuals were encountered with almost equal frequency in both groups.

Greater short-term differences in therapeutic response exist between control and fibrinolysin patients when analysis is restricted to those treated within 5 days of phlebitic onset.

The available data do not permit firm conclusions regarding the apparently favorable influence of fibrinolysin upon the long-term prognosis of phlebitic subjects, but do indicate that recurrence and embolization can be expected in both groups.

The factors that may influence the results obtained with fibrinolytic therapy are discussed and the importance of considering them in studies of this type is emphasized.

Correction by defects in clotting accelerator activity by administration of methionine and vitamin K and of a new sulfhydryl-substituted methylnaphthoquinone, vitamin K-S(II)

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