Anticoagulants in pregnancy

Microvascular reconstruction for complex lower-extremity trauma in pregnancy

Microvascular reconstruction in pregnancy is rare. We report a case of complex distal lower-extremity trauma in early pregnancy reconstructed with a microvascular free muscle flap. A 30-year-old female with 13 weeks gestation had a crush avulsion of the distal left leg with medial malleolar fracture; she had two sessions of debridement, joint stabilising external fixator frame, and a vaccum assisted closure dressing application. Two weeks later, a right latissimus muscle flap was harvested. Flap was transferred to the debrided leg defect. The thoracodorsal vessels were anastomosed end to end to the anterior tibial artery and the concomitant vein. The flap was immediately revascularised. Continuous post-operative heparin infusion was administered. The muscle was covered with split-thickness skin graft 48 hrs later. Healing and post-operative recovery were uneventful. This report suggests that careful surgical and anesthetic techniques, along with a balanced post-operative anticoagulation protocol, can achieve satisfactory microvascular reconstruction in pregnancy.

Placental Drug Transport-on-a-Chip: A Microengineered In Vitro Model of Transporter-Mediated Drug Efflux in the Human Placental Barrier

The current lack of knowledge about the effect of maternally administered drugs on the developing fetus is a major public health concern worldwide. The first critical step toward predicting the safety of medications in pregnancy is to screen drug compounds for their ability to cross the placenta. However, this type of preclinical study has been hampered by the limited capacity of existing in vitro and ex vivo models to mimic physiological drug transport across the maternal-fetal interface in the human placenta. Here the proof-of-principle for utilizing a microengineered model of the human placental barrier to simulate and investigate drug transfer from the maternal to the fetal circulation is demonstrated. Using the gestational diabetes drug glyburide as a model compound, it is shown that the microphysiological system is capable of reconstituting efflux transporter-mediated active transport function of the human placental barrier to limit fetal exposure to maternally administered drugs. The data provide evidence that the placenta-on-a-chip may serve as a new screening platform to enable more accurate prediction of drug transport in the human placenta.

Prosthetic heart valve selection in women of childbearing age with acquired heart disease: a case report

Background

The problem of prosthetic heart valve selection in fertile women with acquired heart defects remains crucial in modern cardiology. Mechanical heart valves require lifelong indirect anticoagulant therapy, which has significant fetal toxicity and is unacceptable for women planning pregnancy. Bioprosthetic heart valves are the best choice for fertile women; however, their durability is limited, and reoperations are required.

Case presentation

We describe the clinical case of a 21-year-old Russian woman with infectious endocarditis who underwent heart valve replacement with an epoxy-treated mitral valve prosthesis.

Conclusions

Epoxy-treated bioprosthetic heart valves can be used without long-term anticoagulant therapy because of their optimal hemodynamic functional parameters. Moreover, their high thromboresistance and resistance to infection improve patients’ quality of life in their late postoperative period. We recommend these valves both in older persons and in young patients including women who are planning 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).

Pregnancy follow-up in a patient with mechanical valve: possible in sub-Saharan Africa?

BACKGROUND

In Africa in general and in Cameroon in particular, post rheumatic cardiopathies are a health care problem, one of the causes of infertility in the women population and a major cause of death among children and adults. Management of a pregnant woman with mechanical heart valve is a complex issue for all health care providers involved in the care of such patients.

PATIENT AND CASE REPORT

Miss A is 26-years old and consulted for cardiac assessment; referred from Bamenda (North-West province of Cameroon) for better management of a cardiac problem including arrhythmia and a history of recurrent tonsillitis. The cardiac echo-dopplerography showed severe post-rheumatic mitral valve regurgitation with pulmonary hypertension and a dysfunctional left ventricle. The patient was later evacuated in a surgical centre in Milan San Donato (Italy) where a St. Jude mechanical heart valve N.27 was implanted. Two years after surgery, during a follow-up visit, the patient brought a pelvic ultrasound showing a single live intrauterine foetus, gestational age estimated at 7 weeks.

CONCLUSION

Management of mechanical valve in a pregnancy context, resulting in a favourable outcome (no thromboembolic events and the delivery of a healthy baby) is possible in sub-Saharan Africa. Close observation, adherence to existing clinical guidelines, patient cooperation and an appropriate technical infrastructure are critical factors to consider.

Rheumatic and nonrheumatic valvular heart disease: epidemiology, management, and prevention in Africa

BACKGROUND

Unlike the Western world, valvular disease ranks among the major cardiovascular afflictions in Africa. Acute rheumatic fever and chronic rheumatic valvular disease in their most virulent form are still commonly encountered and impose a huge burden on limited healthcare resources.

METHODS AND RESULTS

We performed a systematic review of the literature with PubMed using rheumatic fever, rheumatic heart disease, valvular disease, warfarin anticoagulation, and pregnancy as search items. Literature emanating from Africa was emphasized. Epidemiology, current concepts on pathogenesis, and aspects of the medical and surgical management of this disease as seen from an African perspective are presented. The association of pregnancy with mitral stenosis is common and may be fatal if not managed appropriately. A practical approach to these patients is presented to optimize maternal and fetal outcome. Pregnant patients with mechanical valves require careful attention to ensure maternal survival and prevent fetal warfarin embryopathy. Prolonged subcutaneous heparin and frequent monitoring of the partial thromboplastin time are impractical in this setting, and the merits of different anticoagulation regimens are discussed. Congenital submitral aneurysms are a unique cause of mitral regurgitation, with the vast majority of cases originating from sub-Saharan Africa. Although the precise etiology is as yet unclear, the clinical and echocardiographic features are sufficiently characteristic to allow a preoperative diagnosis to be made. Transesophageal echocardiography allows much better definition of the size and anatomic relationships of the aneurysm. Surgical resection can be difficult but is usually curative. Mitral valve prolapse and endocarditis constitute the remaining frequent causes of valvular disease and are discussed briefly.

CONCLUSIONS

The spectrum and presentation of valvular disease in Africa are uniquely different from elsewhere. Together with socioeconomic issues and the HIV pandemic, this fact makes it imperative that further epidemiological and clinical studies be undertaken and guidelines developed that are appropriate to the practice of medicine on the African continent.

Clinical and echocardiographic assessment of pregnant women with valvular heart diseases—maternal and fetal outcome

The study aimed to compare the outcome of pregnancy in women with valvular heart diseases.

MATERIAL

Two hundred and fifty-nine pregnant women with cardiac diseases, aged 18-42, were observed. Group I-158 patients with mitral valve disease: 30 patients with mitral stenosis; 44 patients with mitral regurgitation, 33 patients with combined mitral valve disease, 51 patients with mitral valve prolapse; Group II-54 patients with aortic valve disease: 32 patients with aortic stenosis, 22 with aortic regurgitation; Group III-47 patients after valve replacement (36 mechanical; 11 homograft valves). Medical history and physical examination, NYHA class assessment, ECG, and echocardiography were performed during consecutive trimesters of pregnancy and after delivery.

RESULTS

Clinical deterioration was observed in 38 patients-in 25 women of Group I, 6 women of Group II, and 7 women of Group III. Newborns outcome : 250 healthy (10 prematures, 12 with intrauterine growth retardation), 6 aborted, 2 stillbirths, 1 neonatal death. Method of delivery : 200 vaginally, 53 cesarean sections.

CONCLUSIONS

(1). Pregnants with critical mitral valve stenosis form a high-risk group of life-threatening complications. (2) In women with severe aortic stenosis, pregnancy could lead to sudden clinical status deterioration. (3) Cardiac complications can be expected in patients with left ventricular enlargement and its depressed function. (4) Key factors influencing successful course of pregnancy and labour in patients with prosthetic valves: adequate left ventricular function, properly functioning valves, and effective anticoagulation.

[Anticoagulation of valvular prostheses]

Prosthetic valve replacement has transformed the outcome of patients with severe or poorly tolerated valvular heart disease. Between the two main families of prostheses, only mechanical prostheses require indefinite anticoagulant therapy to lower the thromboembolic risk. National and international guidelines have been published within the past decade. They have outlined how anticoagulation, essentially oral anticoagulant therapy and transient heparin, should be used. The intensity of anticoagulation depends on the type of prosthesis, its position, the presence of atrial fibrillation and the individual's risk of thromboembolism. Monitoring is based on the INR. Temporary recourse to heparin therapy is necessary for all situations in which the risk of major hemorrhage requires more flexible treatment (postoperative period, extracardiac surgery, stroke, severe hemorrhage) or when warfarin is contraindicated because of its risk of inducing malformation (pregnancy). Low molecular weight heparins are not yet authorized for use in prosthesis bearers. Nonetheless, they are being prescribed by more-and-more teams, seduced by the facility of their use, their more stable action and, usually, no need for biological monitoring. And their use is supported by the most recent guidelines, several favorable publications, and the excellent results obtained with them in treating other thromboembolic pathologies. Indispensable to lower the rate of thromboembolic events, anticoagulant therapy bears a hemorrhagic risk that is higher for prolonged and marked anticoagulation. On the other hand, despite effective anticoagulation, the occurrence of thromboemboli can lead to considering the adjunction, in certain cases, of anti-platelet aggregating agents, particularly favored in North America, and recommended in Europe for patients with a predilection for atheromas.

Pregnancy and stroke

This review details the evidence that the risk of stroke is increased in the peripartum and postpartum period rather than the entire 9 months of pregnancy. In women with prior stroke, available evidence suggests that the excess risk of a stroke recurrence in pregnancy is approximately 1% to 2%. Although certain conditions have a particularly strong association with stroke in pregnancy, such as eclampsia, or with the postpartum period, such as cerebral venous thrombosis, the clinical and therapeutic approach to women with stroke during pregnancy should be similar to the approach to stroke in young adults. Strategies for stroke prevention should take into account the competing risks to mother and fetus.

Effect of oral anticoagulant during pregnancy with prosthetic heart valve

This retrospective study aimed to evaluate the risks and outcome of oral anticoagulant use during pregnancy in women with prosthetic heart valves. Between December 1989 and November 1998, 192 females of childbearing age underwent heart valve replacement with a mechanical prosthesis. There were 37 pregnancies in 30 patients during follow-up. Pregnancy was terminated on medical grounds in 5 cases, there were 2 (6%) spontaneous abortions, and 1 (3%) premature birth of a normal baby who died 24 hours later due to asphyxia. The other 29 pregnancies (91%) went to full term and the mothers continued taking oral anticoagulants until a week before the expected date of delivery, then switched to heparin. There was no thromboembolism, valve thrombosis, or maternal mortality. Three babies (10%) had a skeletal deformity: nasal hypoplasia in all 3, with cleft pinna in 1. Continuation of oral anticoagulants during pregnancy provided adequate protection against thromboembolism and valve thrombosis, but the risks of fetal abnormalities and premature delivery should be explained to women of childbearing age with a mechanical valve prosthesis.

The relation between antiphospholipid syndrome-related pregnancy morbidity and non-gravid vascular thrombosis: a review of the literature and management strategies

The antiphospholipid syndrome (APS) is associated with pregnancy morbidity and vascular thrombosis in the presence of circulating antiphospholipid (aPL) antibodies. Clinical manifestations of aPL antibodies represent a spectrum (asymptomatic, pregnancy events, vascular events, or both pregnancy and vascular events), and APS should not be considered a single disease with a predictable outcome. Patients with aPL antibodies are at increased risk of vascular thrombotic events during pregnancy, the postpartum period, and even during long-term follow-up after an APS-related pregnancy event. Therefore, the purpose of this paper is to review the relation between APS-related pregnancy morbidity and vascular thrombosis, and to address the importance of prophylactic therapy during and after APS pregnancies to prevent maternal thrombotic complications. During pregnancy, low-dose aspirin (LDA) should be considered for all patients with aPL antibodies and heparin should be added to LDA in patients fulfilling the Sapporo criteria for definite APS. During delivery, especially with caesarian section, periods without anticoagulation should be kept to an absolute minimum. Some data suggest that LDA might be effective against future non-gravid vascular thrombosis in patients with APS and a history of only pregnancy morbidity.

Pregnancy with St. Jude Medical Mitral Valve Prosthesis

From 1986 to 1995, 513 young women of childbearing age (11 to 45 years) underwent mitral valve replacement with a bileaflet St. Jude Medical prosthesis. Twenty-one patients became pregnant within 3 years postoperatively. The mean age of these patients at the onset of pregnancy was 27 ± 8 years (range, 16 to 43 years). Follow-up was complete for all pregnant patients. Of 11 who continued to take warfarin during pregnancy, one had a premature delivery, 2 had spontaneous abortions, and 8 had therapeutic abortions. Five patients who ceased oral anticoagulant therapy had normal deliveries but 4 underwent reoperation for valve thrombosis postnatally, with concurrent left hemiplegia in one case. The other 5 patients adhered to an anticoagulation protocol for pregnancy; there were 3 normal deliveries, 1 premature birth, and 1 abortion. There is a high risk of thromboembolism in patients with mechanical heart valves whose anticoagulants are interrupted during pregnancy. We believe that careful supervision can reduce maternal morbidity and mortality.

Anticoagulant therapy in special circumstances

Situations often occur in anticoagulated patients that require adjustment of anticoagulation therapy. These situations often place the patient at risk of bleeding, and often there is little clinical data to guide the clinician. This paper reviews several of these situations and offers guidance for the management of patients. The problems reviewed concern the patient on anticoagulants who is or desires to get pregnant, peri-operative management of anticoagulated patients, anticoagulated patients with intracranial bleeding or endocarditis, and the "warfarin refractory" patient.

Anticoagulation in pregnant women with mechanical heart valve prostheses

OBJECTIVE

To evaluate the outcome of pregnancy in women with mechanical heart valve prostheses in relation to the anticoagulant treatment used in the first trimester and the incidence of thrombotic and bleeding complications.

METHODS

92 pregnancies in 59 women were followed between 1986 and 1997. In 31 pregnancies, oral anticoagulants were discontinued when pregnancy was diagnosed and subcutaneous heparin was started (12 500 U every 12 hours) adjusted to prolong the adjusted partial thromboplastin time to twice the control level. In the second trimester oral anticoagulants were resumed but changed to heparin again 15 days before the expected delivery date. In 61 pregnancies oral anticoagulants were continued during the first trimester. The same regimen of heparin was used for delivery.

RESULTS

Abortion or fetal losses were similar (p = 0. 5717) in women exposed to oral anticoagulants in the first trimester (13/61; 25%) compared with those who received adjusted subcutaneous heparin (6/31; 19%). Embolic episodes were more common (p = 0.0029) in women who received heparin (4.92%) compared with those on oral anticoagulants (0.33%). Embolic episodes were cerebral and transient. No valve thromboses were observed. No malformations appeared in the 71 newborns, except for one case of hydrocephalus. There were no maternal deaths secondary to thrombotic complications. The only death was the result of major bleeding after the delivery of a premature stillborn.

CONCLUSIONS

Oral anticoagulants seem to be safer for the mother than adjusted subcutaneous heparin. Heparin does not offer a clear advantage over oral anticoagulation in the pregnancy outcome.

Dose-dependent fetal complications of warfarin in pregnant women with mechanical heart valves

OBJECTIVES

The purpose of this study was to assess the incidence of warfarin fetal complications and whether they are dose-dependent.

BACKGROUND

Gravid patients with mechanical heart valves require long-term anticoagulant therapy. Controversy exists concerning the appropriate treatment of these patients.

METHODS

Forty-three women on warfarin carrying out 58 pregnancies were studied. For each patient with full-term pregnancy a caesarian section was scheduled for the 38th week during brief warfarin discontinuation. Maternal and fetal complications were evaluated. Fetal complications were divided according to the warfarin dosage < or = 5 mg and > 5 mg necessary to keep an international normalized ratio (INR) of 2.5 to 3.5, and analyzed subsequently.

RESULTS

A total of 58 pregnancies were observed: 31 healthy babies (30 full term, 1 premature) and 27 fetal complications (22 spontaneous abortions, 2 warfarin embryopathies, 1 stillbirth, 1 ventricular septal defect, 1 growth retardation) were recorded. Two maternal valve thromboses occurred. No fetal or maternal bleeding was observed during caesarian sections or premature vaginal delivery. Patients whose warfarin doses during pregnancy were > 5 mg had 22 fetal complications, whereas those taking a dose < or = 5 mg had only five fetal complications (p = 0.0001). For an increase of the warfarin dose there was a substantially increased probability of fetal complications (p < 0.0001; p < 0.7316).

CONCLUSIONS

There is a close dependency between warfarin dosage and fetal complications. Patients on warfarin anticoagulation may be delivered by planned caesarian section at the 38th week while briefly interrupting anticoagulation.

Effect of pregnancy on the duration of bovine pericardial bioprostheses

BACKGROUND

This study sought to evaluate the effect of pregnancy on the rate of deterioration of bovine pericardial bioprostheses. To avoid the fetal and maternal risks associated with anticoagulant therapy during pregnancy, the use of bioprostheses has been advocated for young women with cardiac valve disease who may later wish to bear children. Several reports have suggested the probability of pregnancy-related accelerated deterioration of these valves.

METHODS AND RESULTS

The incidence of prosthetic dysfunction and the freedom from deterioration were investigated in 48 women who had 58 pregnancies and in a control group of 167 patients in the same age range. There were 39 cases of prosthetic dysfunction (deaths plus reoperations resulting from valve failure): 12 in the pregnant group for a linearized rate of 3.5% +/- 0.99% (SE) per patient-year and 27 in the control group or 3.4% +/- 0.65% per patient-year (P = not significant). The actuarial freedom from dysfunction was 90.4% (95% confidence interval 77.9 to 96.2) at 5 years and 77.0% (59.7 to 88.3) at 8 years for the pregnancy group and 86.3% (77.3 to 92.0) and 73.4% (56.6 to 84.8), respectively, for the control group ( P = not significant). In the Cox proportional hazard regression analysis, pregnancy did not influence dysfunction. A direct correlation was found between freedom from dysfunction and the patient's age at surgery.

CONCLUSIONS

Pregnancy does not accelerate the rate of deterioration of bovine pericardial bioprostheses. It is more likely that biological valves deteriorate more rapidly in these patients because of their young age.

Effects of Pregnancy on Long-Term Follow-Up of Mitral Valve Bioprostheses

Between 1986 and 1990, 304 females between 11 and 45 (mean, 33.9 ± 6.9) years of age underwent isolated mitral valve replacement with a bioprosthesis. Thirty-nine of the 285 survivors experienced 48 pregnancies during the late follow-up period (group 1). Structural valve deterioration occurred in 25 (64.1%) of these patients and in 70 (28.4%) of the 246 patients (group 2) who did not become pregnant (p < 0.01). The mean time at which structural valve deterioration occurred was 7.01 ± 1.19 years postoperatively (range, 4.74 to 8.36 years) for group 1 patients and 6.76 ± 1.34 years (range, 2.33 to 10.17 years) for group 2 patients (p > 0.05). Freedom from structural valve deterioration at 10 years was 22.9% ± 8.11% for group 1 and 29.24% ± 6.09% for group 2 (p > 0.05). We concluded that pregnancy did not influence the long-term outcome after mitral valve replacement with a bioprosthesis.

Valvular heart disease in pregnancy. A contemporary perspective

Valvular heart disease may have a significant impact on the course and outcome of pregnancy with implications for fetal as well as maternal health. Optimally, serious symptomatic valvular heart disease should be detected and treated before pregnancy. Whether a pregnant woman is known to have valvular heart disease or is diagnosed during pregnancy, it is imperative that she is managed by an experienced multidisciplinary team. Although medical therapy may alleviate symptoms of heart failure in some patients, definitive intervention either with percutaneous balloon valvuloplasty or with surgical valve replacement may be necessary.

Current concepts of anticoagulant therapy in pregnancy

The optimal use of anticoagulants during pregnancy will continue to be controversial until appropriate randomized controlled and prospective trials with adequate sample sizes are completed. The relative low frequency of thromboembolic events, the concerns about maternal and fetal safety of both treatment and withholding treatment, and the reservations about prospectively enrolling pregnant women in treatment trials has sadly dissuaded the appropriate study of this life-threatening condition. North American trials that enroll pregnant women to evaluate the efficacy of LMWH are of preeminent importance owing to their superior bioavailability, ease in dosing, longer half-life, and side effect profile. Similarly, trials evaluating the optimal management of women of childbearing age with valvular disease are critical to reduce the considerable maternal and fetal morbidity and mortality associated with these pregnancies. Such definitive studies will need to be multicenter in design and it is hoped that the National Institutes of Health initiative to enroll pregnant women in clinical trials will at last be realized in the near future.