Begin Mechanical Heart Valves in Women of Childbearing Age An E-Learning Package

Less than 1% of pregnant women have prosthetic heart valves However, nowadays heart valves are often used more successfully in childhood hence the numbers of these women reaching child bearing years are increasing They are an important group as they require specialist care during pregnancy

Learning Objectives What issues are associated with prosthetic heart valves during pregnancy? What specialist care do women with prosthetic heart valves require before and during pregnancy? What methods of contraception are most suitable for these women?

Contents 1. Issues During Pregnancy 2. Care During Pregnancy 3. Contraception 1. Issues During Pregnancy 2. Care Before and During Pregnancy 3. Contraception To go to the relevant section click on the words above 4. Self Test Questions

Issues During Pregnancy

Contents Issues During Pregnancy 1. Valve Types 2. Problems in Pregnancy: Maternal Complications Fetal Complications

Valve Types There are two main types of valves that may be used: Mechanical Valves Bioprostheses Contents

Mechanical Valves Many of these women have mechanical valves They have a high durability and superior haemodynamic profile However, they carry a high risk of valve thrombosis and hence a need for lifelong anticoagulation with its associated problems Valve type, size and position all influence thrombotic risk St Jude’s tilting disc mechanical valve Contents

Bioprostheses Alternative valve types are the tissue valves such as the porcine bioprostheses These eliminate the need for anticoagulation and thus the problems associated with mechanical valves. A Porcine Bioprostheses Contents

Problems in Pregnancy 1.Maternal Complications: High risk of thromboembolic complications due to the hypercoagulable state of pregnancy 2. Fetal Complications: Arise largely as a result of anticoagulation therapy required by the mother Contents

Maternal Complications Pregnancy is a hypercoagulable state Women with mechanical heart valves are therefore at an increased risk of valve thromboembolism even with anticoagulation therapy There is an estimated 25% risk of significant maternal morbidity, such as myocardial infarction and stroke Estimated 3% risk of maternal mortality Contents

Fetal Complications Arise largely as a result of the use of Warfarin (an anticoagulant). Warfarin is fat soluble and crosses the placenta. It can affect the fetus in two ways: 1. If used between 6 th -12 th week of gestation there is a risk of warfarin embryopathy 2. Throughout pregnancy warfarin anticoagulates the fetus leading to a small risk of haemorrhage, particularly cerebral, during pregnancy or delivery Article Link Contents

Care Before and During Pregnancy

Women with mechanical heart valves require special care both before and during pregnancy. This includes: 1. Preconception Counselling 2. Anticoagulation during pregnancy Contents

Preconception Counselling 1. General Advice 2. Specific Advice Contents

General Advice As with any pregnancy it is important to be encouraging, empowering women to make the right choices for them. Lifestyle advice- smoking, drinking, diet and exercise. Advise high dose Folic Acid (5mg). Contents

Specific Advice They should be advised to meet with their cardiologist before stopping contraception The woman needs to be made aware of possible changes to their anticoagulation regimen during pregnancy At the time of first positive pregnancy test it is important that they contact their doctor so that any changes can be made before 6 weeks gestation Contents

Anticoagulation Pregnant women with mechanical heart valves require careful, adequate anticoagulation with frequent monitoring. Women should be given all information about the different anticoagulation regimens enabling them to make an informed choice. Warfarin provides better maternal protection against thromboembolism but may be harmful to the fetus. Heparin is less protective against maternal thromboembolism but is safer for the fetus Contents

Anticoagulation During Pregnancy Most women choose to stop warfarin and replace it with LMWH between 6-12 weeks gestation After the 1 st trimester heparin may be continued or women may elect to re-start warfarin Heparin is usually given from around 36 weeks gestation up to delivery, the mode and timing of which may need to be planned. For a small number of high risk women warfarin is recommended throughout pregnancy, despite the risk to the fetus. Contents

LMWH Dosing Higher doses of LMWH may be required because of an increase in glomerular filtration rate during pregnancy. For example, tinzaparin 175 units per kg o.d., although b.d. dosing may be required LMWH must be monitored by regular peak and trough anti-Xa levels. Aim to maintain both levels between units per ml The patient should be reassured that this is all taken care of at home Article Link Contents

WarfarinDosing Warfarin Dosing The highest risk of thromboembolic events is at the time of conversion from one anticoagulant to another Warfarin should be started at the pre-conception dose and adjusted according to the INR, typically maintaining an INR between , though it may be higher depending on valve type Contents

After Pregnancy Following delivery warfarin is usually resumed. Women should be reassured that warfarin is safe to use while breast feeding. Contents

Contraception

Contraception Women with mechanical heart valves have particular contraceptive needs It is important to discuss contraception with these women - make it a priority The ideal method will have a high efficacy, be safe to use and acceptable to the individual Contents

Preferred Methods Preferred methods are long acting, reversible and efficacious. For example the Mirena IUS, Implanon and Depo Provera Injection According to guidelines published by RCOG these are the preferred methods of contraception for women with mechanical valve replacements LINK TO RCOG GUIDELINES LINK TO RCOG GUIDELINES According to NICE guidelines there is no need for antibiotic cover during insertion of the Mirena IUS for women with prosthetic heart valves Contents

Alternative Methods If the preferred methods are for any reason unacceptable to the woman a trade-off can be made between efficacy and user acceptability. For example: Cerazette- higher efficacy than other forms of POP but only when taken according to instructions Barrier Methods- user error means failure rates are high Sterilisation- only suitable for women who have completed their families but consider alternatives such as male sterilisation Contents

Not Recommended The Combined Oral Contraceptive is not recommended for use in women with mechanical heart valves as the osetrogen component is thrombogenic There is an interaction between the COCP and warfarin so a pill with a higher oestrogen component would be required Article Link Contents

Emergency Contraception Should unprotected intercourse occur, women with mechanical heart valves can be given Levonelle emergency contraception. Note: Levonelle potentiates the effect of warfarin. If taken women should have their INR checked within 48 hours. Contents

Summary As a result of anticoagulation therapy women with mechanical heart valves have particular needs both prior to and during pregnancy. Should they become pregnant it is important to institute an agreed anticoagulation regimen before 6 weeks gestation in discussion with an obstetrician/cardiologist. If in doubt about any aspect of their care contact the regional centre on Contents

Self Test Questions Click Here to Test Yourself Contents

Additional Reading Elkayam U (2005). Valvular heart disease and pregnancy. Part II: prosthetic valves. Journal of the American College of Cardiology; 46(3): McLintock C et al (2009). Maternal complications and pregnancy outcome in women with mechanical heart valves treated with enoxaparin. BJOG; Thorne S et al (2006). Risks of contraception and pregnancy in heart disease. Heart; 92: Vitale N et al (1999). Dose-dependent complications of warfarin in pregnant women with mechanical Heart Valves. Journal of the American College of Cardiology; 33(6):