Pregnancy management and re-delivery tactics in a patient with a prosthetic heart valve

In the last two decades there has been a trend towards an increase in the number of pregnant women with prosthetic heart valves. Obstetricians, therapists, cardiologists have problems in managing these patients, which is due to the physiological characteristics of pregnancy (a tendency to hypercoagulable), the possibility of developing uterine bleeding during childbirth, the difficulty of correcting anticoagulant therapy against caesarean section. Patients with prosthetic heart valves have a risk of developing thromboembolic complications, bacterial endocarditis, dysfunction of the prosthesis due to the formation of fistulas around the prosthesis due to insufficiency of sutures or thrombosis of the artificial valve. According to world statistics, maternal mortality in women with artificial heart valves is 2.9%.

For a long time there were no uniform standards or clinical recommendations for the management of pregnant women with artificial heart valves. In 2003, the recommendations of the American College of Cardiology and the American Heart Association for the management of patients with acquired heart diseases were revised in 2006 and 2008, where there is a separate chapter on the management of pregnant women and recommendations from the European Society of Cardiology on the treatment of cardiovascular disease in pregnant women. In 2010 in our country there were national recommendations "Diagnosis and treatment of cardiovascular diseases in pregnancy", developed by the committee of experts of the All-Russian Scientific Society of Cardiology. These recommendations detail the possible protocols for managing pregnant women with prosthetic heart valves, depending on the type of valve installed, its position and additional risk factors, such as previous thromboembolism or cardiac arrhythmias, the benefits and possible complications associated with the use of a protocol of reference.

The literature on the issue of managing pregnancy with artificial heart valves emphasizes the need for pregnancy planning, a detailed explanation of alternatives to managing a woman and her partner, and providing information about the benefits and risks of each of the protocols for anticoagulant therapy for both the mother and the fetus.

The risk of pregnancy with artificial heart valves depends on the type of prosthesis and its position, as well as on the presence of concomitant pathology. Thus, pregnancy with aortic valve prosthesis represents a less thrombogenic risk than with a prosthetic mitral, pulmonary or tricuspid valve or with multivalve prosthetics. The initial thrombogenicity of the prosthesis depends on its type. Prostheses such as Carbomedics, Medtronic Hall, St. Jude Medicals have low thrombogenicity, whereas Starr-Edwards prostheses are highly thrombogenic. The risk of complications during pregnancy is also increased if there is a history of previous thromboembolism, atrial fibrillation, mitral stenosis, hypercoagulation. To date, many questions remain controversial. There is no consensus on the most preferred type of valve when it is necessary to install it in women planning a pregnancy. Bioprostheses have a low thrombogenic risk, but quickly degenerate. Mechanical valves are durable, but require lifelong anticoagulant therapy and have an increased risk of both thrombotic and hemorrhagic complications. The question of the selection of the valve should be decided individually in each individual case.

Currently, for anticoagulant therapy with artificial heart valves, warfarin and other vitamin K antagonists, heparins (unfractionated and low molecular weight heparins) are used. The use of warfarin provides reliable anticoagulation, but often leads to complications from the fetus (such as embryopathy, spontaneous abortion in early life and premature birth). The total risk of coumarin embryopathy is approximately 5-10% in patients taking warfarin at 5-12 weeks of gestation. The possible connection between the frequency of embryopathy and the dose of the drug is indicated. So the dose of warfarin more than 5 mg per day leads to the development of embryopathy in almost 50% of cases. Control of the blood coagulation system when taking warfarin is controlled by the INR (target level 2.0-3.5, depending on the position of the valve prosthesis).

Heparin does not pose a risk to the fetus, but is not as effective with regard to anticoagulation. The incidence of thromboembolic complications with heparin during the entire pregnancy is 33% (compared with 3.9% when using warfarin). But there are serious complications of the use of heparin from the mother side - bleeding, osteoporosis, heparin induced thrombocytopenia, thromboembolic complications, which limits its use in obstetrical practice. Conducting a pregnant woman on unfractionated heparin is problematic, since it is difficult to constantly monitor the APTTV and maintain its constant level. The use of low molecular weight heparins in such cases remains a controversial issue - their use during pregnancy with prosthetic heart valves is still insufficiently studied.

There are several protocols for the management of pregnancy with an artificial heart valve: an alternative to managing warfarin is the withdrawal of warfarin before conception, with replacement for unfractionated or low-molecular-weight heparin until 13 weeks to reduce the risk of embryopathy. Then warfarin is again prescribed until 34 weeks of gestation with the subsequent transfer of the patient to unfractionated or low molecular weight heparin before delivery. It is also possible to replace warfarin with unfractionated heparin in the period from 5 to 12 weeks, followed by the resumption of warfarin until 35 weeks. From 36 weeks until the birth, warfarin is replaced with heparin. There is a protocol of maintenance at a therapeutic dose of low molecular weight heparin during the entire pregnancy under the control of anti-Xa (it is recommended that the maximum recommended anti-HA value is recommended by the manufacturer 4 hours after subcutaneous injection). Finally, it is possible to maintain the entire pregnancy on unfractionated heparin, maintaining the APTTV level at a level 1.5-2 times higher than its normal values (normally 24-34 seconds). 8 hours before the operation of cesarean section, heparin is canceled with the resumption after birth in a day together with warfarin until the level of INR 2.0 is reached. Then heparin is canceled.

In the event of an obstetric situation requiring emergency delivery while taking warfarin, a fresh frozen plasma is needed to reduce blood loss, since the effect of vitamin K is achieved only within 24 hours. The decision about the anticoagulant therapy during pregnancy should include an assessment of the risks of thromboembolism, including the type and position of the valve, the history of thromboembolic disorders, and the patient's preferences should also influence the choice of therapy.

In the literature there are descriptions of labor in patients with prosthetic heart valves. In GAZU RKB MZ RT since 1981, delivery was performed in 13 patients with prosthetic heart valves. However, in the literature available to us, we have not encountered a description of repeated delivery in a patient with a prosthetic heart valve. Given the relevance and poor knowledge of this issue, we provide our own clinical observation.

In October 2007, a 24-year-old pregnant woman entered the Department of Pathology of Pregnant GASU RKB MH RT with the diagnosis: pregnancy 37-38 weeks, condition after aortic valve replacement for severe aortic insufficiency with bicuspid aortic valve in 1996, cardiac rhythm disturbance in the anamnesis (ventricular tachycardia), widening of the ascending aorta, CHF0, FK1.

From anamnesis: in 1996 she was operated on the aortic valve insufficiency with a bicuspid aortic valve (prosthetics of the aortic valve with the Carbomedics prosthesis). In the postoperative period, I took phenylin 1,5 tablets per day, while maintaining the level of PTI 63-65%. During pregnancy (2007), she took phenilin up to 14-15 weeks, then transferred to warfarin 2.5 mg. (dose adjustment under the control of INR at the level of 2.25-2.5, PTI - 40-50%).

The course of pregnancy: the first and third trimesters without features. In the second trimester for ultrasound, there was a violation of the fetoplacental blood flow of the IA degree. Treatment was carried out to improve the fetoplacental blood flow in a day hospital. On Echocs: AK prosthesis functions normally. The dimensions of the heart cavities are within normal limits. Expansion of the ascending aorta. Moderate mitral and tricuspid regurgitation. Pulmonary artery valve without signs of insufficiency.

Considering extragenital pathology, it was decided to complete the pregnancy by the operation of a cesarean section in a planned manner.

Warfarin is prescribed 2.5 mg. 1 time per day, with dose adjustment to maintain target INR levels in the range 2.0-3.0 and PTI in the range of 50-70% (80-100% norm). 9 days before the delivery of warfarin, heparin was discontinued at a dose of 5000 ED subcutaneously 3 times a day under the control of APTTV (target level of 45 seconds). At the period of 38-39 weeks of pregnancy, the patient underwent a planned operation by caesarean section, a girl of 2890 weight was taken out, by 8-9 points on the Apgar scale. The duration of the operation is 51 min. The blood loss was 700 ml. The operation went without complications. Antibacterial therapy was initiated intraoperatively (after clamping the umbilical cord) and continued in the postoperative period. 10 hours after the operation, heparin 5,000 units was injected subcutaneously 3 times a day under the control of APTT to achieve the target level of APTT. On the third day after delivery, warfarin was taken 2.5 mg each. 1 time per day. At the same time, the dose of heparin was reduced to 2500 units 3 times a day. On day 5 after delivery, the administration of heparin was discontinued. For two days, the dose of warfarin was adjusted with daily monitoring of MNO and PTI. The postpartum period passed without complications. On the 12th day after surgery against the background of taking warfarin in a dose of 5 mg. Per day in the coagulogram stabilized.

The patient is discharged on day 13 after childbirth in a satisfactory condition under the supervision of a cardiologist. Recommended control of PTI and INR in the first week 3 times, in the second week 2 times, in the third week 1 time, in the following weeks 1 time in 2 weeks. In the late postpartum period, complications from the mother and child were not observed. At the moment the girl is 4 years old, growing and developing normally. From peers in development does not lag behind.

In February 2011, against the backdrop of taking a high dose of warfarin (5 mg per day), a second unplanned pregnancy occurred, which resulted in a complete spontaneous abortion for 11 weeks. In August of the same year, at the age of 29, there was a third pregnancy, also unplanned, which the patient decided to keep.

In May 2012, entered the Department of Pathology of Pregnant GASU RKB MZ RT with the diagnosis: pregnancy 36 weeks, a scar on the uterus; condition after aortic valve replacement in 1996 due to a pronounced aortic valve failure with a bicuspid aortic valve, moderate expansion of the ascending aorta. CHF 0. FC 1. Chromosomal abnormality of the fetus (according to ultrasound). Asymmetric form of intrauterine growth retardation. Weighed down a family anamnesis.

The course of this pregnancy: pregnancy occurred unplanned at a dose of warfarin 5 mg. Per day. After revealing the fact of pregnancy, the dose of warfarin was reduced to 3.125 mg. (target INR 2.5-3.5) in order to reduce the teratogenic effect of the drug on the fetus. In the second trimester for ultrasound revealed a violation of the fetoplacental blood flow IA st., Treatment was carried out to improve the fetoplacental blood flow. At the period of 33 weeks of pregnancy with ultrasound, markers of chromosomal abnormality - ventriculomegaly, shortening of tubular bones (asymmetric ZVUR) were found. Family history is burdened - the second husband of the patient has hypochondroplasia, an autosomal dominant type of inheritance with a risk for offspring of 50%. The pregnant woman refused the cordocentesis offered to her.

On the eve of delivery, a fetal ultrasound was performed, a fetal head 37-38 weeks in size, a stomach 35-36 weeks old, tubular bones 31-32 weeks, lateral ventricles 7 mm. Fruit weight 2620 g. A single cord around the neck of the fetus. Myometrium in the projection of the scar is 3,4-3,8 mm.

During Echo CS, there was no abnormality in the function of the aortic valve prosthesis. A moderate expansion of the ascending aorta was noted.

Treatment: the dose of warfarin is reduced to 2.5 mg. Per day. 9 days before the delivery, the pregnant woman was transferred to heparin 5000 ED 3 times a day, then the dose of heparin was increased to 5000 ED 4 times a day under the control of APTT after each injection. 8 hours before delivery, heparin is canceled.

At the gestational age of 38 weeks, a planned cesarean section was performed, a live female weighing 2450 grams, 47 cm tall, was scooped up by 8-9 points on the Apgar scale. The duration of the operation is 40 minutes. Blood loss of 500 ml. Complications were not. To prevent bacterial endocarditis intraoperatively and in the postoperative period, antibacterial therapy is prescribed. The child was examined by a neonatologist, the diagnosis is made: intrauterine hypotrophy of the 1st degree. No other pathology was identified.

The administration of heparin was resumed 12 hours after delivery at 5,000 units 3 times a day. One day after cesarean section, heparin was canceled, and 0.6 mg of fractiparin was administered. 2 times a day, subcutaneously (under the control of D-dimers), on the same day, the use of warfarin in a dose of 2.5 mg was resumed. With subsequent correction of the dose to 5 mg and further to 6.5 mg (to achieve the target INR). On day 5 after surgery, INR 2.3; PTI 50%. Postpartum period without complications.

The patient was discharged on the 9th day after the operation with the child in a satisfactory condition under the supervision of a cardiologist to correct the dose of anticoagulant therapy under the control of the parameters of the blood coagulation system.

According to the literature, the onset and prolongation of pregnancy in women with an artificial heart valve is not recommended. The interest of clinical observation lies in the fact that the patient with the prosthetic heart valve is delivered again with a favorable outcome with adequately selected anticoagulant therapy.

Candidate of Medical Sciences, Assistant of the Department of Obstetrics and Gynecology Nigmatullina Nigina Amonovna. Management of pregnancy and tactics of repeated delivery in a patient with a prosthetic heart valve // Practical medicine. 8 (64) December 2012 / volume 1

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