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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
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 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
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
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
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