Management of pregnancy and tactics of repeat delivery in a patient with a prosthetic heart valve

In the last two decades, there has been a tendency towards an increase in the number of pregnant women with prosthetic heart valves. Obstetricians, therapists, and cardiologists have problems managing such patients, which is due to the physiological characteristics of pregnancy (a tendency to hypercoagulation), the possibility of uterine bleeding during labor, and difficulties in correcting anticoagulant therapy against the background of a cesarean section. Patients with prosthetic heart valves have a risk of developing thromboembolic complications, bacterial endocarditis, and dysfunction of the prosthesis due to the formation of fistulas around the prosthesis due to suture failure 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 guidelines for the management of pregnant women with artificial heart valves. In 2003, the American College of Cardiology and the American Heart Association issued guidelines for the management of patients with acquired heart defects, revised in 2006 and 2008, which include a separate chapter on the management of pregnant women and recommendations of the European Society of Cardiology for the treatment of cardiovascular diseases in pregnant women. In 2010, our country issued national guidelines for "Diagnostics and Treatment of Cardiovascular Diseases during Pregnancy", developed by a committee of experts of the All-Russian Scientific Society of Cardiologists. These guidelines provide a detailed discussion of possible protocols for the management of pregnant women with prosthetic heart valves depending on the type of valve installed, its position and additional risk factors, such as previous thromboembolism or heart rhythm disturbances, the benefits and possible complications of using a particular management protocol.

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

The risk of pregnancy with artificial heart valves depends on the type of the prosthesis and its position, as well as the presence of concomitant pathology. Thus, pregnancy with an aortic valve prosthesis poses a lower thrombogenic risk than with a mitral, pulmonary or tricuspid valve prosthesis 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, while Starr-Edwards prostheses are highly thrombogenic. The risk of complications during pregnancy also increases with a history of previous thromboembolism, atrial fibrillation, mitral stenosis, hypercoagulation. Many issues remain controversial today. There is no consensus on the most preferable type of valve if it needs to be installed in women planning 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 choice of valve should be decided on an individual basis in each individual case.

Currently, warfarin and other vitamin K antagonists, heparins (unfractionated and low molecular weight heparins) are used for anticoagulant therapy in artificial heart valves. The use of warfarin provides reliable anticoagulation, but often leads to complications for the fetus (such as embryopathies, spontaneous abortions in the early stages of pregnancy and premature birth). The total risk of coumarin embryopathies is approximately 5-10% in patients taking warfarin in the 5-12th week of pregnancy. A possible relationship between the frequency of embryopathies and the dose of the drug is indicated. Thus, a warfarin dose of more than 5 mg per day leads to the development of embryopathies in almost 50% of cases. Monitoring of the blood coagulation system when taking warfarin is carried out by monitoring 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 in terms of anticoagulation. The incidence of thromboembolic complications with heparin use throughout pregnancy is 33% (compared to 3.9% with warfarin). However, there are serious complications of heparin use on the maternal side - bleeding, osteoporosis, heparin-induced thrombocytopenia, thromboembolic complications, which limits its use in obstetric practice. Management of a pregnant woman on unfractionated heparin is problematic, since it is difficult to constantly monitor APTT 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 has not yet been sufficiently studied.

There are several protocols for pregnancy management with an artificial heart valve: an alternative to pregnancy management with warfarin is to discontinue warfarin before conception and replace it with unfractionated or low molecular weight heparin before the 13th week to reduce the risk of embryopathies. Then warfarin is prescribed again until the 34th week of pregnancy, followed by transferring the patient to unfractionated or low molecular weight heparin until delivery. It is also possible to replace warfarin with unfractionated heparin in the period from the 5th to the 12th week, followed by resumption of warfarin until the 35th week. From the 36th week until delivery, warfarin is replaced with heparin again. There is a protocol for management with a therapeutic dose of low molecular weight heparin throughout pregnancy under the control of anti Xa (it is recommended to achieve the maximum anti Xa value recommended by the manufacturer 4 hours after subcutaneous injection). Finally, it is possible to manage the entire pregnancy on unfractionated heparin, maintaining the APTT level at a level 1.5-2 times higher than its normal values (normally 24-34 seconds). Heparin is discontinued 8 hours before the cesarean section and resumed after delivery in 24 hours together with warfarin until the INR level reaches 2.0. Then heparin is discontinued.

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

There are descriptions of childbirth in patients with heart valve prostheses in the literature. Since 1981, 13 patients with heart valve prostheses have been delivered at the State Autonomous Healthcare Institution of the Republic of Tatarstan. However, in the literature available to us, we have not come across descriptions of repeated childbirth in a patient with a heart valve prosthesis. Given the relevance and insufficiently studied nature of this issue, we present our own clinical observation.

In October 2007, pregnant woman A., 24 years old, was admitted to the Department of Pathology of Pregnancy of the Republican Clinical Hospital of the Ministry of Health of the Republic of Tatarstan with the diagnosis: pregnancy 37-38 weeks, condition after aortic valve replacement due to severe aortic insufficiency with a bicuspid aortic valve in 1996, history of heart rhythm disturbances (ventricular tachycardia), dilation of the ascending aorta, CHF0, FC1.

From the anamnesis: in 1996, she underwent surgery for aortic valve insufficiency with a bicuspid aortic valve (aortic valve replacement with a Carbomedicsс prosthesis). In the postoperative period, she took phenylin 1.5 tablets per day while maintaining the PTI level of 63-65%. During pregnancy (2007), she took phenylin until 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%).

Pregnancy course: the first and third trimesters are normal. In the second trimester, ultrasound revealed grade IA fetoplacental blood flow disorder. Treatment was performed to improve fetoplacental blood flow in a day hospital setting. EchoCS: the AV prosthesis functions normally. The sizes of the heart cavities are within normal limits. Dilation of the ascending aorta. Moderate mitral and tricuspid regurgitation. The pulmonary artery valve has no signs of insufficiency.

Considering the extragenital pathology, it was decided to terminate the pregnancy by a planned cesarean section.

Warfarin 2.5 mg was prescribed. Once a day, with dose adjustment to maintain target INR levels within 2.0-3.0 and PTI within 50-70% (normal 80-100%). Nine days before delivery, warfarin was discontinued and heparin was prescribed at a dose of 5000 IU subcutaneously 3 times a day under the control of APTT (target level 45 seconds). At 38-39 weeks of pregnancy, the patient underwent a planned cesarean section, a girl weighing 2890 g was delivered, with 8-9 points on the Apgar scale. The duration of the surgery was 51 minutes. Blood loss was 700 ml. The surgery was without complications. Antibacterial therapy was started intraoperatively (after clamping the umbilical cord) and continued in the postoperative period. Ten hours after the surgery, heparin was resumed at 5,000 U subcutaneously 3 times a day under the control of APTT to achieve the target APTT level. On the third day after delivery, warfarin was resumed at 2.5 mg once a day. At the same time, the heparin dose was reduced to 2,500 U 3 times a day. On the 5th day after delivery, heparin was stopped. The warfarin dose was adjusted over two days with daily monitoring of INR and PTI. The postpartum period passed without complications. On the 12th day after the surgery, while taking warfarin at a dose of 5 mg per day, the coagulogram stabilized.

The patient was discharged on the 13th day after delivery in a satisfactory condition under the supervision of a cardiologist. It was recommended to monitor PTI and INR 3 times in the first week, 2 times in the second week, 1 time in the third week, and 1 time in 2 weeks in the following weeks. No complications were observed in the late postpartum period for the mother or child. The girl is currently 4 years old, growing and developing normally. She is not lagging behind her peers in development.

In February 2011, while taking a high dose of warfarin (5 mg per day), a second unplanned pregnancy occurred, ending in a complete spontaneous miscarriage at 11 weeks. In August of the same year, at the age of 29, a third pregnancy occurred, also unplanned, which the patient decided to continue.

In May 2012, she was admitted to the Department of Pathology of Pregnancy of the Republican Clinical Hospital of the Ministry of Health of the Republic of Tatarstan with the diagnosis: 36 weeks of pregnancy, scar on the uterus; condition after aortic valve replacement in 1996 due to severe aortic valve insufficiency with a bicuspid aortic valve, moderate dilation of the ascending aorta. CHF 0. FC 1. Fetal chromosomal anomaly (according to ultrasound data). Asymmetric form of intrauterine growth retardation of the fetus. Burdened family history.

The course of this pregnancy: the pregnancy occurred unplanned at a dose of warfarin of 5 mg per day. After the fact of pregnancy was detected, 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, an ultrasound scan revealed fetoplacental blood flow disorder stage IA, treatment was performed to improve fetoplacental blood flow. At 33 weeks of pregnancy, an ultrasound scan revealed markers of chromosomal abnormality - ventriculomegaly, shortening of tubular bones (asymmetric IUGR). The family history is burdened - the patient's second spouse has hypochondroplasia, an autosomal dominant type of inheritance with a risk to offspring of 50%. The pregnant woman refused the cordocentesis offered to her.

On the eve of delivery, an ultrasound scan of the fetus was performed, revealing: fetal head size 37-38 weeks, abdomen 35-36 weeks, tubular bones 31-32 weeks, lateral ventricles - 7 mm. Fetal weight 2620 g. Single umbilical cord entanglement around the fetal neck. Myometrium in scar projection 3.4-3.8 mm.

During the echocardiography, no dysfunction of the aortic valve prosthesis was detected. Moderate dilation of the ascending aorta was noted.

Treatment: the warfarin dose was reduced to 2.5 mg per day. Nine days before delivery, the pregnant woman was transferred to heparin 5000 IU 3 times per day, then the heparin dose was increased to 5000 IU 4 times per day under the control of APTT after each injection. Heparin was discontinued 8 hours before delivery.

At 38 weeks of pregnancy, a planned cesarean section was performed, a live girl was delivered weighing 2450 g, 47 cm tall, with 8-9 points on the Apgar scale. The duration of the operation was 40 minutes. Blood loss was 500 ml. There were no complications. In order to prevent bacterial endocarditis, antibacterial therapy was prescribed intraoperatively and in the postoperative period. The child was examined by a neonatologist, and the diagnosis was: intrauterine hypotrophy of the 1st degree. No other pathology was revealed.

Heparin administration was resumed 12 hours after delivery at 5000 U 3 times a day. A day after the cesarean section, heparin was discontinued, fraxiparine 0.6 mg was prescribed. 2 times a day subcutaneously (under D-dimer control), on the same day, warfarin was resumed at a dose of 2.5 mg, followed by dose adjustment to 5 mg and then to 6.5 mg (to achieve the target INR). On the 5th day after the operation, INR 2.3; PTI 50%. The postpartum period is uneventful.

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

According to the literature, the onset and prolongation of pregnancy in women with an artificial heart valve is not recommended. The interest of the clinical observation is that the patient with a prosthetic heart valve gave birth 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. Pregnancy management 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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