RHD & Pregnancy – Script
SLIDE 1
Welcome to RHD Australia’s Health Provider Education series. Educational resources for
clinicians by clinicians. RHD Australia is an initiative of Baker IDI, Menzies School of Health
Research and James Cook University and is supported by the Commonwealth Department of
Health and Ageing
This module will investigate how pregnancy impacts on women with rheumatic heart disease.
SLIDE 2
This presentation was developed with the assistance of Jaye Martin, and Barry Walters.
Jaye is a consultant physician based in Broome, Western Australia, and provides specialist
services across the region, travelling by 4WD and light aircraft. Her particular interests are
chronic disease management, viral hepatitis, HIV, rheumatic heart disease and diabetes.
Barry is Clinical Associate Professor of Obstetric Medicine at the University of Western
Australia in Perth, and Adjunct Professor of Medicine at the University of Notre Dame
Australia. He is the current President of the Society of Obstetric Medicine of Australia and New
Zealand.
SLIDE 3
The learning objectives for this presentation are firstly to understand how rheumatic heart
disease can impact on the health of pregnant women. Secondly, you will gain an appreciation of
the significance of valve disease in pregnancy, especially mitral stenosis and aortic stenosis.
Thirdly, to be able to identify which pregnant women will be most at risk of complications from
their rheumatic heart disease, and additionally to know which medications are safe, and which
to avoid. You will gain an understanding of anticoagulation issues associated with pregnancy,
and finally you will have learnt to appreciate the overriding importance of pre conception
counselling in rheumatic heart disease
SLIDE 4
The take home messages for this module are that the normal changes associated with pregnancy
can have an adverse effect on women with rheumatic heart disease, that pre conception
counselling is essential for all women with rheumatic heart disease, and that pregnancy poses a
significant threat to women with rheumatic heart disease. Anticoagulation is always difficult to
manage throughout pregnancy, and it can be hazardous for both baby and mother. Early referral
to a specialist obstetrician familiar with rheumatic heart disease is advisable, as the clinical
management of pregnancy associated with rheumatic heart disease is difficult. Lastly,
contraception and the future management of their rheumatic heart disease should be discussed
with women following delivery and before discharge from hospital.
SLIDE 5
There will be a significant number of abbreviations used during this presentation, so let’s take a
look at them before proceeding further.
AF refers to atrial fibrillation – This is an abnormal and irregular heart rhythm that can occur in
people with rheumatic heart disease especially when it affects the mitral valve
AR is used for aortic regurgitation, this is a leaking aortic valve that links the left ventricle with
the aorta.
ARF refers to acute rheumatic fever – This condition can cause heart inflammation and lead to
RHD
AS is used for aortic stenosis, a sticking aortic valve that makes it difficult for blood to cross it.
CO is used for cardiac output and this is the volume of blood pumped by the heart in one
minute.
Echo is an abbreviation for echocardiogram or heart ultrasound
H2 refers to the second heart sound heard when auscultating or listening to the heart. This
sound is associated with the closing of the aortic and pulmonary valves.
H3 refers to the third heart sound – this can be a normal finding in young people and pregnant
women, but is usually associated with heart problems in older people. It is an extra heart sound
that occurs at the beginning of diastole, when the heart is relaxing and filling with blood, after
the second heart sound or H2. It either occurs as a result of rapid filling of the ventricle (and
this is why it can be normal in young or pregnant people) or because the ventricle is abnormal,
as can occur in heart failure or following a heart attack.
LA refers to the left atrium – one of the four chambers of the heart that is linked to the left
ventricle via the mitral valve
LV is used for left ventricle – the major pumping chamber of the heart that pushes blood across
the aortic valve into the aorta and then the rest of the body
LMWH is the abbreviation for low molecular weight heparin – the lighter component of
heparin that is often used because dosing and administration is easier
MS refers to mitral stenosis, the sticking of the mitral valve so that it does not let blood pass
easily across it.
MR is used for mitral regurgitation, a leaking mitral valve that lets blood leak back into the left
atrium from the left ventricle
MV is used for mitral valve, a valve commonly damaged by rheumatic heart disease
MVA is the abbreviation for mitral valve area, which is a measure of how wide the mitral valve
can open, and this measurement is used to assess severity of MS.
NYHA is the abbreviation for the New York Heart Association – the organisation that
developed a measure of shortness of breath in heart disease
PASP is for pulmonary artery systolic pressure – this is also sometimes called RVSP or right
ventricular systolic pressure and is the measure of pulmonary pressure and gauges pulmonary
hypertension. PBMV is the abbreviation for percutaneous balloon mitral valvotomy – a
relatively non-invasive technique for dealing with mitral stenosis
PND is used for paroxysmal nocturnal dysponea – episodes of shortness of breath at night often
associated with heart failure or mitral valve disease
PR is used for pulmonary regurgitation – a leaking pulmonary valve that links the right
ventricle and the pulmonary artery
RHD refers to rheumatic heart disease – the development of permanent heart valve damage
following repeated episodes of ARF.
TR is used for tricuspid regurgitation – a leaking tricuspid valve that lets blood from the right
ventricle leak back into the right atrium.
SV is used for stroke volume – the volume of blood the heart pumps every beat. Stroke volume
multiplied by heart rate equals CO or cardiac output
SVR is used for systemic vascular resistance – the resistance the heart must work against based
on all the blood vessels in the body.
SLIDE 6
For those who would like more information regarding the management of acute rheumatic fever
and rheumatic heart disease, this can be found in the Australian Guidelines for the Prevention,
Diagnosis and Management of ARF and RHD. These guidelines have been substantially
updated and revised in 2012, are available at the RHD Australia website.
SLIDE 7
There is also a quick reference guide that provides an excellent summary of these guidelines.
SLIDE 8
The Guidelines also provide a synopsis of the key points for the management of pregnancy for
women with rheumatic heart disease.
SLIDE 9
More information regarding a broad range of aspects of the prevention, diagnosis and
management of acute rheumatic fever and rheumatic heart disease can be found at the RHD
Australia website in the Health Provider Education modules. These will be regularly updated
and expanded.
SLIDE 10
The normal haemodynamics of pregnancy
In order to understand the impact of pregnancy upon women with rheumatic valvular heart
disease, it is first necessary to understand the normal haemodynamic changes that occur during
pregnancy. These include a 50% increase in both blood volume and cardiac output at the same
time as a reduction in systemic vascular resistance or SVR. Blood pressure tends to fall in the
first and second trimesters of pregnancy.
It is also important to remember that following birth there is an increase in the circulating blood
volume and venous blood returning to the heart, as blood from the contracting uterus is returned
to the circulation.
SLIDE 11
This slide demonstrates graphically the effects of various stages of gestation upon heart rate,
stroke volume and the product of these, the cardiac output. You can see that these all gradually
increase throughout pregnancy, peaking late in the third trimester. There is also a rapid fall in
heart rate, stroke volume and consequently of course, cardiac output following delivery.
SLIDE 12
It’s also important to note that plasma volume increases by about 50% throughout pregnancy,
and this is what is responsible for the so-called physiological anaemia of pregnancy, where the
same number of red blood cells and amount of haemoglobin is diluted by a larger volume of
plasma.
There can also be a real reduction in total amount of haemoglobin associated with falling iron
stores. You’ll see from this graph that iron supplementation reduces the fall in haematocrit
somewhat, but does not completely compensate for this effect.
SLIDE 13
The normal ECG in pregnancy.
There are also ECG changes that can occur during pregnancy, and again many of these can be
normal. These changes include a sinus tachycardia, mild S-T segment depression, either left or
right axis deviation, and also non-specific T-wave changes.. Both atrial and ventricular ectopics
can increase and these can also be a normal manifestation of pregnancy.
SLIDE 14
Clinical findings in pregnancy.
There are also a number of findings on examination of the cardiovascular system that would not
be considered normal in a non-pregnant woman, but again, can be normal during pregnancy.
These are listed on this slide and include increased splitting of H2 or the second heart sound, a
third heart sound and a mid-systolic murmur. Less commonly a continuous venous hum, known
as a mammary souffle ( pronounced souf), can also be heard on auscultation of the precordium
or front of the chest. Pre-existing stenotic murmurs, that is, mitral and aortic stenosis become
louder, due to the increased cardiac output, but regurgitant murmurs conversely may be quieter
due to decreased systemic vascular resistance and greater forward and less abnormal backward
or regurgitant flow.
SLIDE 15
There are also some echocardiographic changes that occur during pregnancy that again can be
normal. These include mild ventricular enlargement, mild tricuspid and pulmonary
regurgitation, and mild mitral and aortic regurgitation.
SLIDE 16
Cardiac risk in pregnancy.
It is important to understand how the presence of pre-existing heart valve disease can increase
the risk of adverse events during pregnancy. The most concerning valve lesion is mitral
stenosis. This slide graphically illustrates this and shows a patient with mitral stenosis. You’ll
note the mitral valve mean gradient increases during pregnancy compared to the post-partum
state as does the pulmonary pressure demonstrated by the right ventricle systolic pressure or
RVSP.
You will see from the bar chart on the right side of this slide that the risk of adverse events
during pregnancy, both maternal and foetal, is proportional to the severity of mitral valve
disease. Of particular note, there is almost an 80% risk of an adverse event occurring if mitral
stenosis is severe pre-pregnancy.
SLIDE 17
Valvular disease in pregnancy.
The principles of management of women with valvular heart disease during pregnancy can be
divided into four categories.
These are:
1. The vital role of pre-pregnancy planning and counselling,
2. Stratifying a woman’s risk of having an adverse event during pregnancy as a
consequence of her heart disease
3. Defining optimal antenatal management and where this care is best provided.
Contingencies for complications need to be included at this stage. Finally,
4. Where and how the delivery should occur in order to ensure a good outcome both for
mother and child.
SLIDE 18
Pre-pregnancy planning and counselling.
Ideally, women with RHD should be assessed and counselled prior to becoming pregnant. This
of course implies that all pregnancies, including in women with RHD, are planned, which of
course is not always the case.
It is therefore important to consider this in all women of child-bearing age with known RHD,
whether they are sexually active or not and to discuss whether contraception is required. Whilst
the choice of contraception should be discussed with woman and individualised to their
preferences, long acting devices such as Implanon or Depo-Provera are preferred in this setting
because of their low failure rate.
If significant valvular heart disease is present, it is best to discuss this with the woman prior to
conception. The implication that severe valvular disease might lower her chances of a
successful pregnancy will need to be talked over. It is important to reinforce that most women
with RHD can have children; with the main issue being whether the valve disease is best
addressed prior to conception.
Possible procedures for advanced disease may include percutaneous balloon mitral
valvuloplasty, valve repair or valve replacement. If there is a possibility that any of these
procedures may be necessary, then referral to a cardiologist prior to conception is advised.
Pre-conception counselling is also an opportunity to review how well secondary prophylaxis
with benzathine penicillin has been delivered. It is also an opportunity to monitor progression
and severity of valvular heart disease with echocardiography, and to ensure specialist reviews
are up to date.
SLIDE 19
Risk stratification.
Assessing the significance and severity valvular heart disease requires a number of assessments.
The first is history. Symptoms including poor exercise tolerance and shortness of breath on
exertion, at night (called paroxysmal nocturnal dyspnoea), or when lying down (called
orthopnoea), can all indicate moderate to severe valve disease. The New York Heart
Association has a functional classification that can be used to grade the severity of heart disease
based upon how short of breath people become on exertion. This ranges from one, where there
are no symptoms, through to 4 where there are symptoms at rest.
Sometimes getting an accurate assessment of shortness of breath can be difficult. Going for a
brisk walk with the patient, doing a formal assessment of exercise tolerance with a six minute
walking test, or asking family or local health care staff can therefore be helpful.
Echocardiography iscrucial . In particular, information is sought about severity of the mitral and
aortic valve disease, the size and function of the left ventricle and the pulmonary artery
pressure. A poorly functioning left ventricle and an elevated pulmonary pressure is always
concerning.
Finally if the woman has been pregnant previously, then her past obstetric history is important.
An adverse event in a previous pregnancy is highly predictive of adverse events in future
pregnancies. This is particularly the case if there has been no treatment to address the valve
disease in the interim.
Whilst an earlier uncomplicated pregnancy might be reassuring it should be kept in mind that
valve disease can progresses. An earlier uncomplicated pregnancy should not necessarily
reassure you that the current pregnancy will be similarly uncomplicated.
SLIDE 20
The N.Y.H.A. classification.
This slide illustrates in more detail, the New York Heart Association classification of heart
disease based on symptom severity.
Grade 1 disease describes heart disease with no significant symptoms, grading through mild
symptoms for Grade 2, to significant symptoms limiting normal activity for Grade 3, and onto
severe symptoms comprising significant breathlessness at rest, with the patient often being bedbound. Grade 4 symptoms indicate severe valvular heart disease requiring intervention.
SLIDE 21
Maternal outcome and valve disease.
This slide stratifies the risk of adverse maternal outcomes according to the New York Heart
Association classification Grades 1 to 4.
It shows that there is a tendency for any valvular heart disease to worsen during pregnancy,
with women moving from stage 1 and 2 N.Y.H.A. symptoms through to Grade 3 or even Grade
4. Whilst this may occur with aortic and pulmonary valve disease, it is far more prevalent in
mitral valve disease.
SLIDE 22
So when should you worry.
The main factors that should ring alarm bells when assessing a woman with rheumatic valvular
heart disease who is either pregnant, or wishes to become pregnant are listed here.
Factors that predict increased risk during pregnancy include decreased left ventricular systolic
function on echo and significant aortic and/or mitral stenosis particularly when associated with
moderate or severe pulmonary hypertension.
Symptomatic heart disease before pregnancy, or heart failure either before or during pregnancy,
are also poor prognostic indicators.
Risk is also significantly increased if the patient already has a mechanical valve in situ, and
atrial fibrillation is present. Both these conditions require anticoagulation which in itself adds
additional risk to pregnancy and delivery.
SLIDE 23
Maternal and foetal outcomes in patients with RHD.
This slide depicts the increased risk to both maternal and foetal outcomes during pregnancy in
women with RHD compared to matched control women without RHD. There is a 38%
increased risk of heart failure developing during pregnancy, and a 35% risk of maternal
hospitalisation during pregnancy, versus 2% in matched controls for women without RHD.
Similarly, there is a fourfold increase in the risk of pre-term delivery in women with RHD and
one in five babies will have intrauterine growth retardation in this group.
It is important to note that these unfavourable outcomes mostly apply to women with moderate
or severe mitral and/or aortic stenosis.
SLIDE 24
The importance of RHD in obstetric care, particularly for Aboriginal and Torres Strait Islander
women living in northern and Central Australia, is demonstrated here.
The Indigenous populations of northern and Central Australia, those from Far North
Queensland, the Northern Territory and the Kimberley region of Western Australia, have the
highest prevalence of rheumatic heart disease in Australia.
In the Kimberley approximately one in fifty Aboriginal Australians has RHD, with more
women than men being affected. This bar chart shows that the majority of Kimberley women
with rheumatic heart disease are under the age of 40, and therefore, of child-bearing age.
SLIDE 25
We will now look at 3 case studies to illustrate some of the points mentioned.
The first case is that of a 21yr old from Beagle Bay community. Beagle Bay is a small
Aboriginal community two hours’ drive north of the main Kimberley town of Broome in
northern Western Australia.
This lady had known RHD and a pregnancy 12 months ago. She developed pulmonary oedema
during her first labour and now presented requesting advice for another pregnancy.
She fortunately realised that pregnancy required careful planning, but at the same time, was
anxious to become pregnant and was refusing contraception. She frequently did not attend her
planned medical appointments, and her secondary prophylaxis with benzathine penicillin had
been spasmodic.
So what issues should we consider discussing with this lady, and how should we approach
management at this time?
SLIDE 26
Clinical examination may include the following.
A history should be taken regarding smoking and alcohol and a plan put in place to address
these if needed. It’s important to reinforce that there is no safe level of drinking or smoking in
pregnancy and that their effect can be particularly damaging before a woman even knows she is
pregnant.
She may need to lose or gain some weight. Poor maternal nutrition and being underweight or
overweight can be important contributors to intrauterine growth retardation.
Dental review is important at this time and frequently overlooked. A dental review may reduce
the risk of infective endocarditis in the setting of RHD.
If no recent ECG and echocardiogram, these will also be required, as well as a close review of
her medication. She may be on any or several of the medications listed on this slide, and
consideration needs to be given to whether these medications can or should be continued during
pregnancy, whether they should be replaced with an alternative, and whether the medications
should be discontinued prior to conception.
SLIDE 27
The ECG of this case study confirmed that she was in sinus rhythm, and the echocardiogram
showed mixed mitral valve disease with severe mitral regurgitation, and moderate mitral
stenosis with a mitral valve area of 1.8cm2. She also had pulmonary hypertension with a
pulmonary artery systolic pressure of 50 mm of mercury and the left atrial diameter was
increased at 53mm.
SLIDE 28
Assessing the risk and benefit of many drugs used in managing heart disease in the setting of
pregnancy is difficult.
Whilst definite advice is often lacking non-selective beta blockers, frusemide, digoxin,
vasodilators such as hydralazine, nifedipine, verapamil and nitrates are all considered to be safe
in pregnancy. Heparin is also safe, and warfarin after the first trimester may also be considered
reasonable to continue.
The issue of warfarin, particularly in the first trimester, will be discussed in more detail later.
However, ACE inhibitors and the related angiotensin receptor blockers are absolutely
contraindicated in pregnancy, as are other agents such as lipid lowering statin drugs.
SLIDE 29
We will now move onto a second case study, that of a 23yr old woman from a community
called Balgo in the remote East Kimberley. Balgo is located on the northern edge of the Tanami
and Great Sandy Deserts, about 3½hrs drive south of the nearest town, Halls Creek. Halls
Creek has a population of about 2,000 people and a small community hospital with no resident
specialist staff. Balgo is 1,000km by road or about 3hrs by light aircraft from the major centre
of Broome.
This particular lady was physically active, with no exertional symptoms suggestive of heart
disease, although she did have a history of significant alcohol use. At the age of 14 she was said
to have had mild mitral stenosis noted on an echocardiogram. She presented now pregnant at 20
weeks gestation for her first ante natal visit.
On examination there was a pansystolic murmur and possibly also a mid-diastolic murmur and
a loud pulmonary component of the second heart sound.
SLIDE 30
Her echocardiogram showed that she had mitral stenosis.
SLIDE 31
So what are the main issues of concern in this particular patient?
Is the mitral stenosis important and what is her prognosis?
How should the mitral stenosis be managed during pregnancy, during labour, delivery and in
the post-partum period?
SLIDE 32
In order to understand the management of mitral stenosis in pregnancy, it is first important to
understand why mitral stenosis is concerning in pregnancy.
It is important because the pressure gradient across the mitral valve increases during pregnancy.
In turn this worsens the functional severity of the mitral stenosis, because of the normal
increase in heart rate and blood volume associated with pregnancy. This leads to an increase in
left atrial pressure with associated shortness of breath, and an increased risk of pulmonary
oedema, atrial fibrillation and other arrhythmias, as well as pulmonary hypertension.
SLIDE 33
So how can mitral stenosis be managed during pregnancy?
During pregnancy, mild to moderate mitral stenosis is usually managed medically. However if
there is moderate to severe mitral stenosis with a mitral valve area less than 1.5cm2,
consideration should be given to percutaneous balloon mitral valvuloplasty. This is particularly
important to consider in symptomatic women and in those who have an echocardiogram which
demonstrates a raised pulmonary artery systolic pressure above 50 mm of mercury.
SLIDE 34
Medical management of mitral stenosis during pregnancy includes the use of beta blockers or
digoxin for rate control of atrial fibrillation. DC cardioversion can be performed during
pregnancy and should be considered if atrial fibrillation is inadequately controlled on
medications, though often its benefit will only be temporary.
Betablockers may also be useful in sinus rhythm if there is an associated tachycardia and
symptoms. In this case slowing the rate can allow greater time for left ventricular filling across
the stenosed mitral valve.
It is important to avoid anaemia, so timely intervention with iron and folic acid supplements is
essential. Ante natal care can be performed in the usual way in the community, but
consideration should be given to transfer and admission in the third trimester to a larger centre
with more experience in the management of valvular heart disease during delivery and better
facilities.
If atrial fibrillation is present then anticoagulation is required using low molecular weight
heparin. Low molecular weight heparin should also be administered if the echocardiogram
shows a dilated left atrium, left atrial thrombus,and if there is a history of previous thrombosis
or embolic stroke. Monitoring of the efficacy of low molecular weight heparin can be difficult
in pregnancy where normal weight based dosing may not be adequate. Advice should be sought
from specialists regarding the need for regular factor Xa monitoring to direct low molecular
weight heparin dosing.
SLIDE 35
More severe degrees of mitral stenosis may require management with bed rest and diuretics for
left ventricular failure. While beta blockers have the benefit of preventing tachyarrhythmias by
slowing the heart rate and optimising left ventricular filling, procedural intervention is usually
required for symptomatic disease.
SLIDE 36
Getting back to our patient from Balgo, what was the outcome with her pregnancy?
She could not be found for follow up after her echocardiogram. The assistance of the local
clinic staff, Halls Creek Hospital, the community midwife and the local police were required to
track her down. Fortunately she was found, and because she had severe mitral stenosis, she
agreed to be transferred to Perth where she underwent a percutaneous balloon mitral
valvuloplasty.
Her baby was delivered by a normal vaginal delivery, and there were no adverse maternal or
foetal outcomes. However she was pregnant again when next seen for review by the visiting
specialist in Balgo a few months later.
SLIDE 37
We will now discuss the management of aortic stenosis in pregnancy.
Aortic stenosis related to RHD is far less common than mitral stenosis. Mild to moderate aortic
stenosis is usually well tolerated in pregnancy. However percutaneous trans-luminal aortic
valvuloplasty should be considered if symptoms are severe.
Aortic stenosis should be managed medically, in a similar way to the medical management of
mitral stenosis, using diuretics if heart failure develops, and drugs such as beta blockers or
digoxin for rate control of atrial fibrillation if needed.
It is important to note that cardiac surgery, that is, valve replacement, should be avoided if
possible during pregnancy, because there is a high risk of foetal loss. This applies equally to
both the aortic and mitral valve.
SLIDE 38
We will now look at our third case study, that of a 25yr old woman in her first pregnancy with
no known previous cardiac history.
She lives in the community of Looma, which again is a small Aboriginal community about
100km from the nearest significant regional town of Derby in the Kimberley region of Western
Australia. Derby has a population of about 4,000 people with a base hospital and resident
medical officers, but no resident specialists.
This lady had undergone an uneventful pregnancy, except for developing anaemia, with her
haemoglobin falling to 80g/litre. She presented to the hospital in Derby during labour.
SLIDE 39
The labour was prolonged, and required a forceps delivery. During the delivery she sustained a
second degree tear, and had a significant loss of blood approximating about 5 litres. She was
given IV crystalloids and packed red cells as volume resuscitation and responded well. In the
immediate post-partum period, she developed a fever and tachycardia, and was noted to have a
very poor urine output.
She was assessed and thought to be dehydrated, and therefore was given an intravenous fluid
challenge.
SLIDE 40
Following the intravenous fluid she developed significant shortness of breath, and her oxygen
saturations dropped to 90-92%. She was noted on examination to be in pulmonary oedema, and
also had sacral oedema, a raised JVP, and a tachycardia of 104 beats per minute.
A pan-systolic murmur consistent with mitral regurgitation was noted.
SLIDE 41
This slide shows her chest x-ray, which confirms the presence of pulmonary oedema. It also
suggests that she has a dilated left atrium.
SLIDE 42
She had an urgent echocardiogram, which showed moderate aortic regurgitation with moderate
to severe mitral regurgitation
However there were no significant signs of pulmonary hypertension, with normal right heart
pressures and only mild tricuspid regurgitation.
SLIDE 43
Mitral and aortic regurgitation.
Mitral regurgitation is the most common valvular lesion in RHD. It is usually well tolerated
during pregnancy unless there is a sudden deterioration as may occur with the rupture of a
chordae tendon. Pulmonary oedema is treated in the usual way with diuretics. Whilst
vasodilators are rarely required they may be needed for control of systemic hypertension. It
should be remembered that ACE inhibitors and angiotensin receptor blockers are usually
contraindicated in pregnancy.
SLIDE 44
The normal haemodynamic changes associated with the post-partum period are outlined here.
There is an increase in systemic venous return with relief of compression of the inferior vena
cava after delivery, combined with a phenomenon known as autotransfusion. This refers to the
contracting uterus returning blood to the systemic circulation with an associated increase in
circulating blood volume. While this effect is potentially counteracted by blood loss during
delivery, this is often less than the increase associated with autotransfusion. The end result is a
substantial increase in ventricular filling pressures, cardiac output and total peripheral
resistance.
The outcome of this can be pulmonary oedema, particularly if other factors come into play. It is
important to note that this haemodynamic adaptation can take 6-12 weeks post-partum to return
to pre-pregnancy values, so this increased risk of pulmonary oedema can persist for some
weeks following delivery.
SLIDE 45
The tendency to pulmonary oedema may be exacerbated if the woman also has anaemia,
infection or tachycardia, or suffered from pre-eclampsia. This bar chart shows that the plasma
oncotic pressure in pregnancy is reduced compared to the non-pregnant state, particularly if
pre-eclampsia has occurred. Thus for the same increase in left atrial and left ventricular filling
pressure the risk of pulmonary oedema will be higher as fluid is more likely to leak from the
pulmonary vessels into the lung.
SLIDE 46
This chart illustrates graphically the relative importance of contributing factors that predispose
women to pulmonary oedema in the post-partum period. You will see that one of the most
important factors is iatrogenic or health provider induced fluid overload. This is almost as
important as the contribution of pre-existing cardiac disease, and more important than preeclampsia, which in itself is also significant contributor.
Interestingly, the use of tocolytics is relevant in about 25% of women who develop post-partum
pulmonary oedema contributing the same percentage as patients with pre-existing cardiac
disease.
SLIDE 47
This slide illustrates the strain that is put on a woman’s heart during labour. You will see that
during a uterine contraction the cardiac output increases markedly, but falls back to baseline
24hrs after delivery.
SLIDE 48
It is also important to note that the cardiac output is dependent upon the woman’s position
during labour. Particularly in women with known valvular heart disease, it is recommended
they be positioned as shown in the diagram in the bottom right hand corner of the slide, that is,
lying not absolutely supine, but rolled slightly to the right, which can be facilitated by placing a
wedge under the back on the left hand side.
SLIDE 49
This slide lists the risk factors associated with heart failure during pregnancy. The left hand
column lists maternal factors such as age, obesity, presence of other heart disease or
hypertension, presence of other chronic diseases such as diabetes and being an Aboriginal or
Torres Strait Islander woman. Use of amphetamines and cocaine are also risk factors. The right
hand column lists pregnancy associated factors, including severe pre-eclampsia, sepsis,
anaemia, use of tocolytics or steroids, low albumin, twin pregnancies and the use of crystalloid
intravenous fluids.
SLIDE 50
It is important to note that women with mitral stenosis tolerate tachycardia poorly during
delivery, whereas women with aortic stenosis tolerate hypovolemia poorly. It is very important
that women with high risk mitral and/or aortic stenosis undertake delivery in a planned fashion,
in a centre with experience in managing such deliveries. It cannot be overemphasised how
important it is to consider early transfer for valvuloplasty or high risk cardiac surgery if there is
concern that this may be needed.
SLIDE 51
This slide lists the important predictors of an adverse pregnancy outcome in women with heart
disease. The most important factors are any previous cardiac event or arrhythmia, New York
Heart Association functional class greater than 2, or the presence of cyanosis, a presence of left
heart obstruction, defined as a mitral valve area less than 2cm2 and/or an aortic valve area of
less than 1.5cm2, and finally, the presence of systemic ventricular dysfunction with a left
ventricular injection fraction less than 40%.
SLIDE 52
This bar chart shows the risk of a cardiac event according to the presence of these 4 mentioned
risk factors.
If none of these risk factors are present, then only a very small percentage of pregnancies will
be affected by a significant cardiac event, whereas if more than one of these risk factors are
present, then 60% or more pregnancies can be expected to be complicated by a cardiac event.
SLIDE 53
Therefore, early referral to a regional centre for ongoing care should be considered if the
woman is thought to be of intermediate or high cardiac risk, defined as a risk score of one or
more of these factors present, or with risk factors specific to the particular valve lesion they
possess. Conversely, delivery in a community hospital can occur if there is a low cardiac risk,
that is, a risk score of zero with no lesion-specific risk factors.
SLIDE 54
In general terms, vaginal delivery is encouraged and should be the aim in all women except
those with severe mitral stenosis and severe pulmonary hypertension. Usually these conditions
will require an elective caesarean section in a tertiary hospital.
Cardiac monitoring can be non-invasive in the presence of mild and moderate valvular heart
disease. Antibiotic prophylaxis is not typically required, but should be given if there is
prolonged labour and/or ruptured membranes. Principles of management include aiming for as
short a second stage of labour as possible, and managing labour with a multi-disciplinary team
of experts.
There should however be a low threshold for obstetric intervention, and close post-partum
monitoring is absolutely essential because of the increased risk of pulmonary oedema.
SLIDE 55
As a general principle cardiac valve surgery should be avoided during pregnancy. This is
because cardio pulmonary bypass in pregnancy is associated with an up to 5% risk of maternal
mortality, and a very high foetal mortality rate of 16-33% depending upon the case series
examined.
SLIDE 56
Possible procedures for the management of valvular disease in pregnancy include valvuloplasty
which should be done by a percutaneous approach wherever possible. Other options include
valve repair and valve replacement only if this is not possible, but these later two options
involve surgery with its attendant risk to mother and baby.
SLIDE 57
This survival curve demonstrates that the long term outcome of percutaneous balloon mitral
valvotomy undertaken in pregnancy is very similar in women who were pregnant at the time of
the procedure compared to women who were not pregnant when the procedure was performed.
SLIDE 58
So we will now move onto valve replacement with a mechanical or bioprosthetic valve.
One of the most important considerations after the decision has been made that a valve needs to
be replaced is to consider the type of valve, a bio prosthetic valve or a mechanical heart valve.
The advantage of a bioprosthetic valve is that anticoagulation is not required; however, these
valves will need to be replaced earlier than a mechanical valve. It is important to remember that
most women undergoing these procedures will survive, and will need to have a repeat valve
replacement at some stage in their life if a bioprosthetic valve is used.
Whilst mechanical valves may last longer they are associated with a higher thromboembolic
risk and anticoagulation will be required. The safe management of anticoagulation in remote
communities is always difficult, and requires substantial support from primary health services.
Further information regarding the management of anticoagulation in RHD can be found
elsewhere in this education series.
There is also a higher risk of infective endocarditis with mechanical valves and this should be
consider particularly if there is a history of infective endocarditis.
SLIDE 59
The use of anticoagulation in pregnancy is a difficult and challenging. When anticoagulation is
required, early discussion with a specialist physician, haematologist or obstetrician is essential.
The two agents currently used for anticoagulation in pregnancy are heparin, either low
molecular weight or unfractionated, and warfarin.
The risk of thromboembolism if anti-coagulation is inadequate needs to be balanced against the
risk of bleeding associated with over anti-coagulation, and the possible risk of teratogenicity
from the use of warfarin in pregnancy.
SLIDE 60
Ideally, interventions for advanced rheumatic heart disease that do not require anticoagulation,
such as valvuloplasty, valve repairs or bioprosthetic valves, are preferable in women who plan
to become pregnant.
However you will no doubt encounter women with mechanical heart valves who require
anticoagulation who either are pregnant or wish to become pregnant. It is therefore necessary to
weight up the risks and benefits of using heparin or warfarin, or a combination of both
throughout the pregnancy.
While warfarin is associated with foetal damage especially if given in the first trimester, recent
evidence indicates this may be avoided if the warfarin dose can be kept to 5mg or less during
pregnancy. However, there is still a risk of intra cranial haemorrhage to the foetus if warfarin
used.
The maternal risks of anticoagulation have already been highlighted, that is, bleeding in the
case of over anticoagulation versus thromboembolism, particularly valve thrombosis and stroke
if anticoagulation is inadequate.
Essentially there are three options for anticoagulation in pregnancy, as detailed on the next
slide.
SLIDE 61
The first is to continue warfarin at a dose of 5mg or less daily throughout pregnancy, changing
to intravenous heparin or low molecular weight heparin at 36-37 weeks, until elective delivery.
This option is the best option for the heart valve, providing anticoagulation is adequate on this
low dose of Warfarin, but of course is not such a good option for the baby.
The second option therefore is to plan pregnancy, and use low molecular weight Heparin
during the first trimester, changing to Warfarin at 13 weeks, and continuing Warfarin until
Week 36. Low molecular weight heparin should then be introduced from Week 36 onwards,
until labour and factor Xa levels used to monitor adequacy of anticoagulation with the low
molecular weight heparin.
The third option is to use low molecular weight heparin throughout pregnancy, again with
factor Xa monitoring. This third option would seem to be the safest for the baby, but there is
doubt that it is a good an option for the mother in terms of adequate anticoagulation, and at the
present time there is no data to confirm or refute this suggestion.
Low molecular weight heparin should be stopped for delivery, and for 24hrs post-partum, then
re-introduced whilst the mother is commencing warfarin. Low molecular weight heparin can
then be discontinued after five days and when INR levels are adequate on warfarin therapy.
SLIDE 62
So, in drawing to a close, let’s revisit our take home message from the beginning of the
presentation.
Normal changes associated with pregnancy can have an adverse impact on women with
rheumatic heart disease, pre conception counselling is vital for all women with rheumatic heart
disease, pregnancy poses a significant threat to women with severe rheumatic heart disease,
management of anticoagulation in pregnancy is difficult and risky, management of pregnancy
in women with rheumatic heart disease can be difficult and requires early referral to specialists,
and finally, the issue of contraception should be discussed prior to hospital discharge postpartum.
SLIDE 63
More information regarding a broad range of aspects of the prevention, diagnosis and
management of acute rheumatic fever and rheumatic heart disease can be found at the RHD
Australia website in the Health Provider Education modules. These will be regularly updated
and expanded.
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You can also register at the Health Provider Education website for additional resources. To
download this and other PowerPoint presentations for your own use in your local practice, and
additional assessment items for training providers, and if you would like to be notified about
new modules and updates, please ‘Like’ us on Facebook at the provided address below.
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And finally, for those of you who would like to test your knowledge regarding the information
presented in this module please go to the brief self-assessment quiz at the link provided on this
website.