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Mechanical Heart Valves in Mechanical Heart Valves in Women of Childbearing AgeWomen 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 ObjectivesLearning 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?

ContentsContents

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 Issues During PregnancyPregnancy

Contents

Issues During Pregnancy Issues During Pregnancy

1. Valve Types

2. Problems in Pregnancy:

Maternal Complications

Fetal Complications

Valve TypesValve Types

There are two main types of valves that may be used:

Mechanical Valves

Bioprostheses

Contents

Mechanical ValvesMechanical 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

BioprosthesesBioprostheses

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 BioprosthesesContents

Problems in PregnancyProblems 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 ComplicationsMaternal 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 ComplicationsFetal 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 6th-12th 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 Care Before and During During

PregnancyPregnancy

Care Before and Care Before and During PregnancyDuring 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 CounsellingPreconception Counselling

1. General Advice

2. Specific Advice

Contents

General AdviceGeneral 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 AdviceSpecific 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

AnticoagulationAnticoagulation

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

AnticoagulationAnticoagulation During Pregnancy During Pregnancy

Most women choose to stop warfarin and replace it with LMWH between 6-12 weeks gestation

After the 1st 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 DosingLMWH 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 0.7-1.2 units per

ml

The patient should be reassured that this is all taken care of at home

Article LinkContents

WarfarinWarfarin DosingDosing

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 2.5-3.5, though it

may be higher depending on valve type

Contents

After PregnancyAfter Pregnancy

Following delivery warfarin is usually

resumed.

Women should be reassured that warfarin

is safe to use while breast feeding.

Contents

ContraceptionContraception

ContraceptionContraception

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 MethodsPreferred 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

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 MethodsAlternative 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 RecommendedNot 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 ContraceptionEmergency 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

SummarySummary

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 01133928154.

Contents

Self Test QuestionsSelf Test Questions

Click Here to Test Yourself

Contents

Additional ReadingAdditional Reading

• www.rcog.org.uk• Elkayam U (2005). Valvular heart disease and pregnancy. Part II: prosthetic valves.

Journal of the American College of Cardiology; 46(3): 0735-1097• McLintock C et al (2009). Maternal complications and pregnancy outcome in

women with mechanical heart valves treated with enoxaparin. BJOG; 1585-1592• Thorne S et al (2006). Risks of contraception and pregnancy in heart disease.

Heart; 92: 1520-1525• 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): 1637-1641