Maternal and fetal sequelae of anticoagulation during pregnancy

Vitamin K status and cognitive function in healthy older adults

Evidence is accumulating that vitamin K could have a role in cognition, especially in aging. Using data from the Québec Longitudinal Study on Nutrition and Successful Aging (NuAge), a cross-sectional analysis was conducted to examine the associations between vitamin K status, measured as serum phylloquinone concentrations, and performance in verbal and non-verbal episodic memory, executive functions, and speed of processing. The sample included 320 men and women aged 70 to 85 years who were free of cognitive impairment. After adjustment for covariates, higher serum phylloquinone concentration (log-transformed) was associated with better verbal episodic memory performances (F = 2.43, p = 0.048); specifically with the scores (Z-transformed) on the second (β = 0.47; 95% confidence interval [CI] = 0.13-0.82), third (β = 0.41; 95% CI = 0.06-0.75), and 20-minute delayed (β = 0.47; 95% CI = 0.12-0.82) free recall trials of the RL/RI-16 Free and Cued Recall Task. No associations were found with non-verbal episodic memory, executive functions, and speed of processing. Our study adds evidence to the possible role of vitamin K in cognition during aging, specifically in the consolidation of the memory trace.

Vitamin K-dependent carboxylation of matrix Gla-protein: a crucial switch to control ectopic mineralization

Vascular mineralization has recently emerged as a risk factor for cardiovascular morbidity and mortality. Previously regarded as a passive end-stage process, vascular mineralization is currently recognized as an actively regulated process with cellular and humoral contributions. The discovery that the vitamin K-dependent matrix Gla-protein (MGP) is a strong inhibitor of vascular calcification has propelled our mechanistic understanding of this process and opened novel avenues for diagnosis and treatment. This review focuses on molecular mechanisms of vascular mineralization involving MGP and discusses the potential for treatments and biomarkers to monitor patients at risk for vascular mineralization.

Prenatal exposures associated with neurodevelopmental delay and disabilities

Neurobehavioral teratology refers to the study of the abnormal development of the structure and the behavioral functions of the central nervous system, which result from exposure to exogenous agents during prenatal development. The focus of this review is the effects of various prenatal exposures on human neurodevelopment. Studies that deal with the adverse effects of infectious agents (rubella, cytomegalovirus, and toxoplasma), teratogenic drugs (e.g., antiepileptic drugs such as phenytoin, valproate, and carbamazepine, coumarin derivatives, and retinoids), alcohol, and other substances of abuse will be reviewed. Additionally, prenatal exposure to industrial or environmental chemicals (e.g., lead, methylmercury, and polycarbonated biphenyls) as well as exposure of the embryo or fetus to high amounts of ionizing radiation will be addressed. Possible mechanisms of selected neurobehavioral teratogens will also be discussed.

Inferior Vena Cava Filter Placement during Pregnancy: An Adjuvant Option When Medical Therapy Fails

The authors present a case of a 27-year-old multiparous woman, with multiple thrombophilia, whose pregnancy was complicated with deep venous thrombosis requiring placement of a vena cava filter. At 15th week of gestation, following an acute deep venous thrombosis of the right inferior limb, anticoagulant therapy with low-molecular-weight heparin (LMWH) was instituted without improvement in her clinical status. Subsequently, at 18 weeks of pregnancy, LMWH was switched to warfarin. At 30th week of gestation, the maintenance of high thrombotic risk was the premise for placement of an inferior vena cava filter for prophylaxis of pulmonary embolism during childbirth and postpartum. There were no complications and a vaginal delivery was accomplished at 37 weeks of gestation. Venal placement of inferior vena cava filters is an attractive option as prophylaxis for pulmonary embolism during pregnancy.

Vasoactive exposures during pregnancy and risk of microtia

BACKGROUND

Little is known about the etiology of nonsyndromic microtia. This study investigated the hypothesis that microtia is caused by vascular disruption.

METHODS

The study analyzed data from the population-based National Birth Defects Prevention Study (NBDPS) for deliveries between 1997 and 2005. Four hundred eleven nonsyndromic cases of microtia, with or without additional defects, were compared to 6560 nonmalformed infants with respect to maternal exposures to vasoactive medications and smoking during the periconceptional period and conditions that have previously been associated with vascular events (multiple gestation, maternal history of type 1, type 2, or gestational diabetes, and hypertension). Odds ratios (ORs) were estimated with multivariable models, controlling for the effects of race/ethnicity, education, periconceptional folic acid use, and study center.

RESULTS

Risk estimates for vasoactive medications and smoking were not meaningfully increased. Maternal type 1/2 diabetes was diagnosed before or during the index pregnancy in 4% and 1% of cases, respectively, compared to 1% and 0.05% of controls; the adjusted OR for these two groups combined was 7.2 (95% confidence interval [CI], 3.9-13.1). Gestational diabetes was observed for 9% of cases and 6% of controls; the OR was moderately elevated (OR, 1.4; 95% CI, 0.9-2.0). ORs were also increased for multiple gestations (OR, 2.5; 95% CI, 1.5-4.2) and pre-existing hypertension (OR, 1.6; 95% CI, 1.0-2.5).

CONCLUSIONS

Because ORs were only elevated for diabetes and not for vasoactive exposures or other potential vascular events, findings suggest that some microtia occurrences may be part of the diabetic embryopathy rather than manifestations of vascular disruption. Birth Defects Research (Part A), 2013. © 2012 Wiley Periodicals, Inc.

ADHERENCE IN PREGNANCY: A SYSTEMATIC REVIEW OF THE LITERATURE

“Clinical decisions and research programs ultimately depend on the reliable and valid measurement of adherence. Yet, 50 years of research in this field have not provided the data necessary to answer critical measurement questions.”.

Assaying embryotoxicity in the test tube: current limitations of the embryonic stem cell test (EST) challenging its applicability domain

Testing for embryotoxicity in vitro is an attractive alternative to animal experimentation. The embryonic stem cell test (EST) is such a method, and it has been formally validated by the European Centre for the Validation of Alternative Methods. A number of recent studies have underscored the potential of this method. However, the EST performed well below the 78% accuracy expected from the validation study using a new set of chemicals and pharmaceutical compounds, and also of toxicity criteria, tested to enlarge the database of the validated EST as part of the Work Package III of the ReProTect Project funded within the 6th Framework Programme of the European Union. To assess the performance and applicability domain of the EST we present a detailed review of the substances and their effects in the EST being nitrofen, ochratoxin A, D-penicillamine, methylazoxymethanol, lovastatin, papaverine, warfarin, β-aminopropionitrile, dinoseb, furosemide, doxylamine, pravastatin, and metoclopramide. By delineation of the molecular mechanisms of the substances we identify six categories of reasons for misclassifications. Some of these limitations might also affect other in vitro methods assessing embryotoxicity. Substances that fall into these categories need to be included in future validation sets and in validation guidelines for embryotoxicity testing. Most importantly, we suggest conceivable improvements and additions to the EST which will resolve most of the limitations.

Evaluating patient values and preferences for thromboprophylaxis decision making during pregnancy: a study protocol

BACKGROUND

Pregnant women with prior venous thromboembolism (VTE) are at risk of recurrence. Low molecular weight heparin (LWMH) reduces the risk of pregnancy-related VTE. LMWH prophylaxis is, however, inconvenient, uncomfortable, costly, medicalizes pregnancy, and may be associated with increased risks of obstetrical bleeding. Further, there is uncertainty in the estimates of both the baseline risk of pregnancy-related recurrent VTE and the effects of antepartum LMWH prophylaxis. The values and treatment preferences of pregnant women, crucial when making recommendations for prophylaxis, are currently unknown. The objective of this study is to address this gap in knowledge.

METHODS

We will perform a multi-center cross-sectional interview study in Canada, USA, Norway and Finland. The study population will consist of 100 women with a history of lower extremity deep vein thrombosis (DVT) or pulmonary embolism (PE), and who are either pregnant, planning pregnancy, or may in the future consider pregnancy (women between 18 and 45 years). We will exclude individuals who are on full dose anticoagulation or thromboprophylaxis, who have undergone surgical sterilization, or whose partners have undergone vasectomy. We will determine each participant's willingness to receive LMWH prophylaxis during pregnancy through direct choice exercises based on real life and hypothetical scenarios, preference-elicitation using a visual analog scale ("feeling thermometer"), and a probability trade-off exercise. The primary outcome will be the minimum reduction (threshold) in VTE risk at which women change from declining to accepting LMWH prophylaxis. We will explore possible determinants of this choice, including educational attainment, the characteristics of the women's prior VTE, and prior experience with LMWH. We will determine the utilities that women place on the burden of LMWH prophylaxis, pregnancy-related DVT, pregnancy-related PE and pregnancy-related hemorrhage. We will generate a "personalized decision analysis" using participants' utilities and their personalized risk of recurrent VTE as inputs to a decision analytic model. We will compare the personalized decision analysis to the participant's stated choice.

DISCUSSION

The preferences of pregnant women at risk of VTE with respect to the use of antithrombotic therapy remain unexplored. This research will provide explicit, quantitative expressions of women's valuations of health states related to recurrent VTE and its prevention with LMWH. This information will be crucial for both guideline developers and for clinicians.

Vascular calcification: the price to pay for anticoagulation therapy with vitamin K-antagonists

Vitamin K-antagonists (VKA) are the most widely used anti-thrombotic drugs with substantial efficacy in reducing risk of arterial and venous thrombosis. Several lines of evidence indicate, however, that VKA inhibit not only post-translational activation of vitamin K-dependent coagulation factors but also synthesis of functional extra-hepatic vitamin K-dependent proteins thereby eliciting undesired side-effects. Vascular calcification is one of the recently revealed side-effects of VKA. Vascular calcification is an actively regulated process involving vascular cells and a number of vitamin K-dependent proteins. Mechanistic understanding of vascular calcification is essential to improve VKA-based treatments of both thrombotic disorders and atherosclerosis. This review addresses vitamin K-cycle and vitamin K-dependent processes of vascular calcification that are affected by VKA. We conclude that there is a growing need for better understanding of the effects of anticoagulants on vascular calcification and atherosclerosis.

Natural history and management of cervical spine disease in chondrodysplasia punctata and coumarin embryopathy

PURPOSE

Chondrodysplasia punctata (CDP) is a group of skeletal dysplasias manifesting with progressive cervical instability that leads to neurological deficits and eventual death. The major clinical features of CDP also present in a phenocopy known as coumarin embryopathy (CE) which results from coumarin exposure during pregnancy. The objective of this study was to assess treatment strategies employed for children affected by CDP or CE with cervical instability and to determine a strategy on how best to diagnose and treat affected neonates.

METHODS

We performed a systematic review of the English literature for cases reporting cervical spine involvement in CDP and CE and identified 44 such patients. We extracted clinical information on these disorders and identified two patients from our craniovertebral junction database of over 6,000 patients evaluated at our institution.

RESULTS

Patients most frequently present with hyperreflexia (21%) and weakness (21%), and there were various conservative treatment strategies. Twenty-one percent of patients who were treated conservatively had neurological complications in their clinical course. There were two deaths reported, one resulting from conservative treatment and one from surgical treatment. We also report long-term follow-up analysis for a patient treated at our institution for the last 30 years and agree with all other reports that suggest that monitoring patients for neurological changes is essential to prevent further neurological injury.

CONCLUSIONS

This study emphasizes the need for careful neurological and surgical evaluation of pediatric patients with cervical spine abnormalities affected by CDP or CE in order to prevent progressive instability.

Di Sala syndrome

Di Sala syndrome or fetal warfarin syndrome/fetal warfarin embryopathy is a rare condition as result of fetal exposure due to maternal ingestion of warfarin during pregnancy. The authors report here a male infant with this condition whose mother was suffering from rheumatic mitral valvular heart disease for which she underwent prosthetic mitral valvular replacement surgery and put on injectable long acting penicillin and oral low-molecular weight anticoagulant drug (warfarin) for life long. The patient presented with facial dysmorphism, pectus excavatum, stippled epiphyses dolichocephaly, brachydactyly, polydactyly short neck and growth retardation. Shortened fourth metacarpal bones were also noted in this case which was not yet reported in literatures, to the best of our knowledge.

Pregnancy-associated venous thromboembolism: prevention and treatment

Pregnancy is associated with an increased risk of venous thromboembolism (VTE) and this condition remains an important cause of maternal morbidity and mortality. The use of anticoagulant therapy for treatment and prophylaxis of VTE during pregnancy is challenging because of the potential for fetal, as well as maternal, complications. Although evidence-based recommendations for the use of anticoagulants have been published, given the paucity of available data, guidelines are based largely upon observational studies and from data in nonpregnant patients. This article reviews the available literature and provides guidance for the management and prevention of VTE during pregnancy.

Vitamin K and the nervous system: an overview of its actions

The role of vitamin K in the nervous system has been somewhat neglected compared with other physiological systems despite the fact that this nutrient was identified some 40 y ago as essential for the synthesis of sphingolipids. Present in high concentrations in brain cell membranes, sphingolipids are now known to possess important cell signaling functions in addition to their structural role. In the past 20 y, additional support for vitamin K functions in the nervous system has come from the discovery and characterization of vitamin K-dependent proteins that are now known to play key roles in the central and peripheral nervous systems. Notably, protein Gas6 has been shown to be actively involved in cell survival, chemotaxis, mitogenesis, and cell growth of neurons and glial cells. Although limited in number, studies focusing on the relationship between vitamin K nutritional status and behavior and cognition have also become available, pointing to diet and certain drug treatments (i.e., warfarin derivatives) as potential modulators of the action of vitamin K in the nervous system. This review presents an overview of the research that first identified vitamin K as an important nutrient for the nervous system and summarizes recent findings that support this notion.

Vitamin K, an emerging nutrient in brain function

Historically discovered for its role in blood coagulation, there is now convincing evidence that vitamin K has important actions in the nervous system. As a unique cofactor to the γ-glutamyl carboxylase enzyme, vitamin K contributes to the biological activation of proteins Gas6 and protein S, ligands for the receptor tyrosine kinases of the TAM family (Tyro3, Axl, and Mer). Functionally, Gas6 has been involved in a wide range of cellular processes that include cell growth, survival, and apoptosis. In brain, vitamin K also participates in the synthesis of sphingolipids, an important class of lipids present in high concentrations in brain cell membranes. In addition to their structural role, sphingolipids are now known to partake in important cellular events such as proliferation, differentiation, senescence and cell-cell interactions. In recent years, studies have linked alterations in sphingolipid metabolism to age-related cognitive decline and neurodegenerative diseases such as Alzheimer's disease (AD). Emerging data also point to unique actions of the K vitamer menaquinone-4 (MK-4) against oxidative stress and inflammation. Finally, there is now data to suggest that vitamin K has the potential to influence psychomotor behavior and cognition. This review presents an overview of what is known of the role of vitamin K in brain function.

VTE, thrombophilia, antithrombotic therapy, and pregnancy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

The use of anticoagulant therapy during pregnancy is challenging because of the potential for both fetal and maternal complications. This guideline focuses on the management of VTE and thrombophilia as well as the use of antithrombotic agents during pregnancy.

METHODS

The methods of this guideline follow the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

We recommend low-molecular-weight heparin for the prevention and treatment of VTE in pregnant women instead of unfractionated heparin (Grade 1B). For pregnant women with acute VTE, we suggest that anticoagulants be continued for at least 6 weeks postpartum (for a minimum duration of therapy of 3 months) compared with shorter durations of treatment (Grade 2C). For women who fulfill the laboratory criteria for antiphospholipid antibody (APLA) syndrome and meet the clinical APLA criteria based on a history of three or more pregnancy losses, we recommend antepartum administration of prophylactic or intermediate-dose unfractionated heparin or prophylactic low-molecular-weight heparin combined with low-dose aspirin (75-100 mg/d) over no treatment (Grade 1B). For women with inherited thrombophilia and a history of pregnancy complications, we suggest not to use antithrombotic prophylaxis (Grade 2C). For women with two or more miscarriages but without APLA or thrombophilia, we recommend against antithrombotic prophylaxis (Grade 1B).

CONCLUSIONS

Most recommendations in this guideline are based on observational studies and extrapolation from other populations. There is an urgent need for appropriately designed studies in this population.

Oral anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

The objective of this article is to summarize the published literature concerning the pharmacokinetics and pharmacodynamics of oral anticoagulant drugs that are currently available for clinical use and other aspects related to their management.

METHODS

We carried out a standard review of published articles focusing on the laboratory and clinical characteristics of the vitamin K antagonists; the direct thrombin inhibitor, dabigatran etexilate; and the direct factor Xa inhibitor, rivaroxaban

RESULTS

The antithrombotic effect of each oral anticoagulant drug, the interactions, and the monitoring of anticoagulation intensity are described in detail and discussed without providing specific recommendations. Moreover, we describe and discuss the clinical applications and optimal dosages of oral anticoagulant therapies, practical issues related to their initiation and monitoring, adverse events such as bleeding and other potential side effects, and available strategies for reversal.

CONCLUSIONS

There is a large amount of evidence on laboratory and clinical characteristics of vitamin K antagonists. A growing body of evidence is becoming available on the first new oral anticoagulant drugs available for clinical use, dabigatran and rivaroxaban.

Ucmaa (Grp-2) is required for zebrafish skeletal development. Evidence for a functional role of its glutamate γ-carboxylation

UCMA (alternatively named GRP) is a novel member of the family of γ-carboxyglutamate (Gla) containing proteins that is mainly expressed in cartilage. We have used the zebrafish as a model organism to study UCMA function. Due to the whole genome duplication two Ucma genes are present in zebrafish, ucmaa and ucmab, located on chromosomes 25 and 4, respectively. UCMA gene structure, alternative splicing and protein sequence are highly conserved between mammals and zebrafish and Ucmaa and Ucmab are expressed in zebrafish skeletal tissues. Ucmaa is first detected in the notochord at 18 hpf and expression continues during notochord development. In addition, it is widely present in the developing craniofacial cartilage. In contrast, the weakly expressed Ucmab can be first detected at specific sites in the craniofacial cartilage at 96 hpf, but not in notochord. Knockdown of ucmaa leads to severe growth retardation and perturbance of skeletal development. The cartilage of the morphants has a decreased aggrecan and collagen II content. Similar malformations were observed when glutamate γ-carboxylation was inhibited by warfarin treatment, indicating that glutamate γ-carboxylation is crucial for Ucma function and pointing to a role of UCMA in the pathogenesis of "warfarin embryopathies" and other human skeletal diseases.

Lifelong low-phylloquinone intake is associated with cognitive impairments in old rats

In a previous report, we showed vitamin K to preferentially accumulate in brain regions rich in white matter and to positively correlate with certain sphingolipids. In rodents, pharmacological vitamin K deficiency has resulted in behavioral perturbations. To gain insight on the role of vitamin K status on brain function, we investigated learning abilities (Morris water maze), motor activity (open field), and anxiety (elevated plus maze) in distinct groups of 6-, 12-, and 20-mo-old female Sprague-Dawley rats that had been fed diets containing low (L; ~80 μg/kg diet), adequate (A; ~500 μg/kg diet), or high (H; ~2000 μg/kg diet) levels of phylloquinone (μg/kg diet; n = 9-12/diet) since weaning. In 20-mo-old rats, sphingolipids (cerebroside, sulfatide, sphingomyelin, ceramide, and gangliosides), phylloquinone, and menaquinone-4 were also assessed in cerebellum, midbrain, pons medulla, striatum, and hippocampus. Lifetime consumption of a low-vitamin K diet resulted in cognitive deficits in the 20-mo-old rats, with those in the L group having longer latencies than those in the H group (P < 0.05); this was associated with higher concentrations of ceramides in the hippocampus (P < 0.05) and lower gangliosides in the pons medulla and midbrain (P < 0.05). The low-vitamin K diet did not affect cognition at 6 and 12 mo of age, nor did it affect motor activity or anxiety at any age. Although much remains to be elucidated about the mechanism of action of vitamin K in cognition, this report points to vitamin K as an important nutritional factor contributing to cognitive health during aging.

Developmental effects of coumarin and the anticoagulant coumarin derivative warfarin on zebrafish (Danio rerio) embryos

Coumarin and warfarin, two substances which are intensively metabolized in animals and humans, were tested for teratogenicity and embryo lethality in a 3-day in vitro assay using zebrafish embryos. Warfarin is a coumarin derivative, but in contrast to the mother substance warfarin has anticoagulant properties. Both substances produced teratogenic and lethal effects in zebrafish embryos. The LC(50) and EC(50) values for coumarin are 855 μM and 314 μM, respectively; the corresponding values for warfarin are 988 μM and 194 μM. For coumarin, three main or fingerprint endpoints (malformation of head, tail and growth retardation) were identified, whereas malformation of tail was the only fingerprint endpoint of warfarin. The analysis of the ratios between the zebrafish embryo effect concentrations of both substances and human therapeutic plasma concentrations confirmed the teratogenic potential of warfarin, as well as the equivocal status of coumarin.

Teratogenic exposures

A consideration of teratogenic exposures includes not only an agent (chemical, radiation, biologic) but an exposure level and timing of exposure. There are criteria by which exposures are evaluated for a causal connection with an abnormal outcome. We here review some teratogenic exposures and discuss how they were initially described and confirmed. We have limited our discussion to some of the exposures for which a connection to structural malformations has been accepted in some quarters, and we indicate some exposures for which a causal association awaits confirmation. We recommend that counselors find a reliable and updatable source of information on exposures during pregnancy.

Prosthetic heart valve thrombosis, anticoagulation and pregnancy: a case report and review of literature

In pregnant patients with a prosthetic heart valve (PHV), anticoagulation with warfarin is associated with embryopathy, foetal loss early in pregnancy and maternal bleeding complications in the delivery period. The optimal anticoagulation strategy in the pre-pregnancy period and during pregnancy itself is controversial and a matter of debate. We describe a patient with PHV in the pre-pregnancy period and in a subsequent pregnancy. The optimal anticoagulation treatment strategy in women in their reproductive years with mechanical valve thrombosis is discussed. (Neth Heart J 2007;15:306-9).

Novel CYP2C9 and VKORC1 gene variants associated with warfarin dosage variability in the South African black population

AIM

Warfarin is a widely used therapeutic agent for long-term oral anticoagulation worldwide. Its administration is challenging owing to its narrow therapeutic range and serious adverse effects. Several environmental factors and numerous genes, of which CYP2C9 and VKORC1 are the most important, have been associated with interindividual dosage variability. Many studies have been conducted to understand warfarin dosage variability better, the majority of which have been focused on the Caucasian and African-American populations. Very little information is available regarding genetic influences of warfarin dosage variability in the South African black population.

MATERIALS & METHODS

In this study, we genotyped 213 South African black individuals for CYP2C9 and VKORC1 variants and a small subset of environmental factors that may be responsible for warfarin dosage variability.

RESULTS

We observed 26 novel SNPs and seven previously described CYP2C9 variants and three previously described but no novel VKORC1 SNPs. Only 11 of the CYP2C9 variants and two of the VKORC1 variants were observed at high enough allele frequencies to assess their impact on warfarin dosage.

CONCLUSION

We demonstrate that CYP2C9*8 and two novel CYP2C9 SNPs (g.16179 and g.46028) are associated with a decrease in warfarin dosage, β-blockers are independently associated with a decrease in warfarin dosage and two known VKORC1 variants (rs7200749 and rs7294) are associated with an increase in warfarin dosage. The CYP2C9 and VKORC1 variants and a small subset of environmental factors used in the study explain approximately 45% of warfarin dosage variability in the South African black population.

Peripartum pulmonary embolism

Pregnancy is an example of Virchow's triad predisposing to the development of venous thromboembolism (VTE). Specific risk factors for antepartum and postpartum VTE have been identified. The diagnosis of pulmonary embolism in pregnancy is complicated by the physiologic changes of pregnancy as well as physicians' apprehension about ordering radiologic studies during pregnancy because of concerns with fetal well-being. Therapy for VTE is complicated by pregnancy physiology affecting medication pharmacokinetics and bioavailability, and the unpredictable occurrence of labor during therapeutic anticoagulation.

Deep vein thrombosis: a clinical review

Background:

Deep vein thrombosis (DVT) is the formation of blood clots (thrombi) in the deep veins. It commonly affects the deep leg veins (such as the calf veins, femoral vein, or popliteal vein) or the deep veins of the pelvis. It is a potentially dangerous condition that can lead to preventable morbidity and mortality.

Aim:

To present an update on the causes and management of DVT.

Methods:

A review of publications obtained from Medline search, medical libraries, and Google.

Results:

DVT affects 0.1% of persons per year. It is predominantly a disease of the elderly and has a slight male preponderance. The approach to making a diagnosis currently involves an algorithm combining pretest probability, D-dimer testing, and compression ultrasonography. This will guide further investigations if necessary. Prophylaxis is both mechanical and pharmacological. The goals of treatment are to prevent extension of thrombi, pulmonary embolism, recurrence of thrombi, and the development of complications such as pulmonary hypertension and post-thrombotic syndrome.

Conclusion:

DVT is a potentially dangerous condition with a myriad of risk factors. Prophylaxis is very important and can be mechanical and pharmacological. The mainstay of treatment is anticoagulant therapy. Low-molecular-weight heparin, unfractionated heparin, and vitamin K antagonists have been the treatment of choice. Currently anticoagulants specifically targeting components of the common pathway have been recommended for prophylaxis. These include fondaparinux, a selective indirect factor Xa inhibitor and the new oral selective direct thrombin inhibitors (dabigatran) and selective factor Xa inhibitors (rivaroxaban and apixaban). Others are currently undergoing trials. Thrombolytics and vena caval filters are very rarely indicated in special circumstances.

Transfer of Heparin Across the Human Perfused Placental Lobule

A system of dual perfusion of an isolated lobule of term human placenta was used as a model to study the transfer of heparin from maternal to foetal circulation. The metabolic viability of the system was assessed by measuring β-HCG and alkaline phosphatase levels in both maternal and foetal perfusates. Creatinine and antipyrine were used as markers to determine juxtaposition of the maternal and foetal circulations. Results of this study indicate that following administration of a single bolus dose of heparin into the maternal circulation, its concentration declined slowly from 99·01 ±2·98 at 15 min to 97·23 ±4·12% and transfer of heparin in the foetal circulation was linear and increased from 0·10% ±0·05% at 15 min to 0·46 ±0·19% over a period of 120 min. The maternal (MAUC) and foetal (FAUC) concentration-time integrals were found to be 70160 ± 1332 and 340 ± 30 int. units min mL−1, respectively. Placental permeability of heparin and creatinine, calculated as the ratio of foetal concentration to the integral maternal–foetal concentration difference, was 8·65 × 10−5 ± 0·80 × 10−5 and 0·033 ±0006 mL min−1 g−1 of perfused placental weight, respectively. These data suggest that heparin was transferred from the maternal to the foetal circulation in small quantities.

Stroke during pregnancy: therapeutic options and role of percutaneous device closure

Percutaneous device closure of patent foramen ovale has developed into a therapeutic option for patients with presumed cryptogenic stroke. The appropriate use of these therapies relies on appropriate clinical assessment, as well as an understanding of the potential advantages of certain closure devices. Pregnancy is an uncommon scenario for stroke, but nonetheless represents a hypercoaguable state which may predispose to thromboembolism. We describe a case of stroke during pregnancy treated with percutaneous device closure; the role of, and alternatives to, device closure are discussed, as are specific issues related to device selection and the interventional procedure.

Drug safety in pregnancy: utopia or achievable prospect? Risk information, risk research and advocacy in Teratology Information Services

Even though from preclinical testing to drug risk labeling, the situation with drugs in pregnancy has improved substantially since the thalidomide scandal, there is still an increasing need to provide healthcare professionals and patients with updated individualized risk information for clinical decision making. For the majority of drugs, clinical experience is still insufficient with respect to their safety in pregnancy. There is often uncertainty in how to interpret the available scientific data. Based on 20 years of experience with Teratology Information Services (TIS) cooperating in the European Network of Teratology Information Services (ENTIS) methods of risk interpretation, follow-up of exposed pregnancies through the consultation process and their evaluation is discussed. Vitamin K antagonists, isotretinoin and angiotensin (AT) II-receptor-antagonists are presented as examples of misinterpretation of drug risks and subjects of research based on observational clinical data recorded in TIS. As many TIS are poorly funded, advocacy is necessary by establishing contacts with decision makers in health politics and administration, informing them of the high return in terms of health outcomes and cost savings provided by TIS as reference institutions in clinical teratology.

The effect of warfarin dosage on maternal and fetal outcomes in pregnant women with prosthetic heart valves

There are several challenges in the management of pregnant women with mechanical heart valves. Pregnancy increases the risk of thromboembolism and there is currently no consensus on the safest anticoagulation method during pregnancy. The objective of the study was to determine the correlation between the warfarin dose and pregnancy outcome in pregnant women with prosthetic heart valves. Warfarin in pregnancy was associated with a low risk of valve thrombosis or maternal death. The risk for fetal abnormalities was not related to the maternal warfarin dosage. However, the risk for stillbirth was significantly increased with increasing doses of warfarin.

The "warfarin window" in pregnancy: the importance of half-life

Anticoagulation therapy during pregnancy in women with prosthetic cardiac valves is a therapeutic challenge. The use of vitamin K antagonists such as warfarin during pregnancy carries the potential for serious risks to the fetus, especially if these drugs are administered during the first trimester or at term. Between 6 and 12 weeks' gestation, fetal synthesis of proteins crucial for bone and cartilage formation may be impaired by warfarin, resulting in the well-defined "warfarin embryopathy." One of the most commonly suggested regimens involves the substitution of heparin for warfarin between 6 and 12 weeks' gestation to minimize the risk of warfarin embryopathy. Warfarin has a long half-life; following a single dose, the terminal elimination half-life is about one week, with a mean effective half-life of 40 hours. To date, all existing guidelines have ignored this long elimination half-life. If a policy of substituting heparin for warfarin between 6 and 12 weeks' gestation is followed, we suggest that substitution should begin at a much earlier gestational age. Substitution starting at 6 weeks' gestation may be too late to avoid embryopathy.

Ischemic Stroke during Pregnancy and Puerperium

Ischemic stroke during pregnancy and puerperium represents a rare occurrence but it could be a serious and stressful event for mothers, infants, and also families. Whenever it does occur, many concerns arise about the safety of the mother and the fetus in relation to common diagnostic tests and therapies leading to a more conservative approach. The physiological adaptations in the cardiovascular system and in the coagulability that accompany the pregnant state, which are more significant around delivery and in the postpartum period, likely contribute to increasing the risk of an ischemic stroke. Most of the causes of an ischemic stroke in the young may also occur in pregnant patients. Despite this, there are specific conditions related to pregnancy which may be considered when assessing this particular group of patients such as pre-eclampsia-eclampsia, choriocarcinoma, peripartum cardiomiopathy, amniotic fluid embolization, and postpartum cerebral angiopathy. This article will consider several questions related to pregnancy-associated ischemic stroke, dwelling on epidemiological and specific etiological aspects, diagnostic issue concerning the use of neuroimaging, and the related potential risks to the embryo and fetus. Therapeutic issues surrounding the use of anticoagulant and antiplatelets agents will be discussed along with the few available reports regarding the use of thrombolytic therapy during pregnancy.

Prenatal findings in a fetus with contiguous gene syndrome caused by deletion of Xp22.3 that includes locus for X-linked recessive type of chondrodysplasia punctata (CDPX1)

The X-linked recessive type of chondrodysplasia punctata (CDPX1) is a skeletal disorder that is characterized by stippled calcification at an epiphyseal nucleus and the surrounding soft tissue, short stature and an unusual face because of nasal hypoplasia. In most of the patients, this condition is noted after birth because of a characteristic face or respiratory problems. Here, we report a fetus with CDPX1. Two-dimensional ultrasound examination revealed unexplained polyhydramnios and a male fetus. Fetal biometry showed shortened long bones. Three-dimensional ultrasonography clearly demonstrated a hypoplastic nose with a depressed nasal bridge and contracture of wrists and fingers. Chromosome analysis of the amniotic fluid cells revealed the 46,Y,del(X)(p22.3) karyotype. Fluorescence in situ hybridization revealed a deletion of subtelomeric sequences at the Xpter and STS gene, but not a deletion of the KAL gene. The genomic copy number analysis demonstrated terminal deletion of 8.33 Mb that included SHOX, CSF2RA, XG, ARSE, NLGN4 and STS genes. We think that our case presents typical features of a fetus with this disorder and will be of great help in prenatal ultrasound diagnosis.

Warfarin embryopathy: fetal manifestations

During the period 1991-2007, autopsy was undertaken in 13 fetuses with warfarin embryopathy. Pregnancy data and radiographic babygrams were available in each instance. Gestational age ranged from 17 to 37 weeks. Eleven of the fetuses had the characteristic nasal hypoplasia, but only three had radiological epiphyseal stippling. Cerebral hemorrhage was a major feature of autopsy in 8 of the fetuses, and it is evident that bleeding is a significant factor in the pathogenesis of warfarin embryopathy. A wide variety of additional visceral manifestations which were observed at autopsy have been tabulated. There was no obvious correlation between maternal or gestational age and the presence and severity of any specific embryopathic feature. No information was available concerning the dose and timing of warfarin administration in this series.

Vitamin K and vascular calcifications

The role of vitamin K in the synthesis of some coagulation factors is well known. The implication of vitamin K in vascular health was demonstrated in many surveys and studies conducted over the past years on the vitamin K-dependent proteins non-involved in coagulation processes. The vitamin K-dependent matrix Gla protein is a potent inhibitor of the arterial calcification, and may become a non-invasive biochemical marker for vascular calcification. Vitamin K(2) is considered to be more important for vascular system, if compared to vitamin K(1). This paper is reviewing the data from recent literature on the involvement of vitamin K and vitamin K-dependent proteins in cardiovascular health.

Maternal-fetal and neonatal pharmacogenomics: a review of current literature

Pharmacogenomics, the study of specific genetic variations and their effect on drug response, will likely give rise to many applications in maternal-fetal and neonatal medicine; yet, an understanding of these applications in the field of obstetrics and gynecology and neonatal pediatrics is not widespread. This review describes the underpinnings of the field of pharmacogenomics and summarizes the current pharmacogenomic inquiries in relation to maternal-fetal medicine-including studies on various fetal and neonatal genetic cytochrome P450 (CYP) enzyme variants and their role in drug toxicities (for example, codeine metabolism, sepsis and selective serotonin reuptake inhibitor (SSRI) toxicity). Potential future directions, including alternative drug classification, improvements in drug efficacy and non-invasive pharmacogenomic testing, will also be explored.

A prospective trial showing the safety of adjusted-dose enoxaparin for thromboprophylaxis of pregnant women with mechanical prosthetic heart valves

OBJECTIVE

To determine whether dosage adjustment of enoxaparin during pregnancy, to maintain a peak anti-Xa of 1.0 to 1.2 U/mL, is safe for women with mechanical prosthetic heart valves (MPHV).

DESIGN

A prospective observational study.

SETTING

This study was performed at Charlotte Maxeke Johannesburg Academic Hospital from 2007 to 2009.

POPULATION

Fifteen women with MPHVs.

METHODS

Women were treated with enoxaparin with dosage adjustment to achieve a peak anti-Xa of 1.0 to 1.2 U/ mL.

MAIN OUTCOME MEASURES

Main outcomes measured were prosthetic valve thrombosis, bleeding, and maternal mortality.

RESULTS

There was no maternal mortality. None of the women developed valvular thrombosis during pregnancy. In all, 2 women developed epistaxis and another developed spotting per vaginum.

CONCLUSION

Our data show that enoxaparin may be administered safely during pregnancy to pregnant women with MPHV when there is dosage adjustment throughout pregnancy to maintain an anti-Xa of 1.0 to 1.2 U/mL.

Prophylaxis for venous thromboembolic disease in pregnancy and the early postnatal period

BACKGROUND

Venous thromboembolic disease (TED), although rare, is a major cause of maternal mortality and morbidity, hence methods of prophylaxis are often used for women at risk. This may include women delivered by caesarean section, those with a personal or family history of TED and women with inherited or acquired thrombophilias (conditions that predispose people to thrombosis). Many methods of prophylaxis carry a risk of side effects, and as the risk of TED is low, it is possible that the benefits of thromboprophylaxis may be outweighed by harm. Current guidelines for clinical practice are based on expert opinion only, rather than high quality evidence from randomised trials.

OBJECTIVES

To determine the effects of thromboprophylaxis in women who are pregnant or have recently delivered and are at increased risk of TED on the incidence of venous TED and side effects of treatment.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2009).

SELECTION CRITERIA

Randomised trials comparing one method of thromboprophylaxis with placebo or no treatment, and randomised trials comparing two (or more) methods of thromboprophylaxis.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently and resolved any discrepancies by discussion.

MAIN RESULTS

Sixteen trials met the inclusion criteria but only 13 trials, involving 1774 women, examining a range of methods of thromboprophylaxis, contributed data for the outcomes of interest. Four of them compared methods of antenatal prophylaxis: low molecular weight heparin (LMWH) versus unfractionated heparin (UFH) (two studies), and heparin versus no treatment (two studies). Eight studies assessed postnatal prophylaxis after caesarean section; one compared hydroxyethyl starch with unfractionated heparin; four compared heparin with placebo; and the other three compared UFH with LMWH. One study examined prophylaxis in the postnatal period.The small number of statistically significant findings in this review are largely derived from trials which are not of high methodological quality. It was not possible to assess the effects of any of these interventions on most outcomes, and especially on rare outcomes such as death, TED and osteoporosis, because of small sample sizes and the small number of trials making the same comparisons.There was some evidence of side effects associated with thromboprophylaxis.

AUTHORS' CONCLUSIONS

There is insufficient evidence on which to base recommendations for thromboprophylaxis during pregnancy and the early postnatal period. Large scale randomised trials of currently-used interventions should be conducted.