Heart disease is the leading cause of maternal mortality in the UK. Deaths from acquired conditions such as ischaemic heart disease are increasing and often occur in patients with no history of heart disease, thus emphasising the need for vigilance for risk factors in women of childbearing age. All women with known heart disease should have pre-pregnancy counselling to assess for maternal and fetal risk. Women deemed to be at moderate or high risk should be under the care of a specialist antenatal team with experience of managing women with heart disease in pregnancy. Conditions that are considered particularly high risk (mortality >10%) include Marfan syndrome with dilated aortic root, severe left heart obstructive lesions, pulmonary hypertension, and severe left ventricular dysfunction. This article reviews the management of women with heart disease during pregnancy, labour and in the puerperium.
- maternal medicine
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Cardiac disease is now the leading cause of maternal mortality in the UK1 and the numbers of deaths have been increasing steadily over the past two decades. The main cause of the rise in maternal cardiac deaths is an increase in acquired conditions such as ischaemic heart disease (IHD). This is due to both trends in lifestyle which have led to increasing numbers of pregnancies in women with risk factors including obesity, diabetes and smoking, and also the changing attitudes of society with older women becoming pregnant. Furthermore, women with pre-existing disease often now consider pregnancy.
Acquired heart disease is frequently undiagnosed before pregnancy, remaining undetected until pregnancy exposes underlying heart disease or precipitates symptoms for the first time. Diagnosis may be delayed because many of the symptoms and signs that occur in decompensated heart disease, such as shortness of breath and ankle swelling, are commonly experienced by the woman in a ‘normal pregnancy’.
In contrast to acquired disease, maternal deaths from congenital heart disease have declined despite increasing numbers of patients reaching childbearing age and patients with higher risk conditions now becoming pregnant. Congenital heart disease does, however, remain a considerable cause of both maternal and fetal morbidity. These women should have access to specialist ‘high risk’ pre-pregnancy counselling and antenatal care.
It is important to recognise that most women with heart disease are able to tolerate a pregnancy with a successful outcome and these women should not be advised against pregnancy inappropriately. All women with known heart disease should receive expert pre-pregnancy counselling and advice on safe and effective contraception.
This article reviews the haemodynamic changes that occur in pregnancy and discusses the approach to the woman with heart disease in pregnancy, including the pre-pregnancy assessment and management during delivery and in the puerperium.
Haemodynamic changes in pregnancy
Circulatory changes start early on in the pregnancy and peak towards the end of the second trimester (figure 1). They are significant and can have an impact even on healthy women; the risk of pregnancy in the woman with heart disease is largely determined by their ability to adapt to these changes.
Plasma volume increases by 30–50% during pregnancy, leading to an increased stroke volume. This increased stroke volume along with an elevated resting heart rate results in an increase in cardiac output by up to 50%. Circulating oestrogens and prostaglandins along with a low resistance placental bed lead to a drop in systemic vascular resistance of up to 30%, and as a result a mild decrease in blood pressure despite the elevated cardiac output. There is a 20–30% increase in red cell mass resulting in an increased total blood volume and a relative anaemia. Oxygen consumption increases throughout pregnancy to meet the metabolic needs of both mother and fetus.
These changes persist for 2–3 weeks post-delivery but may not completely resolve for up to 12 weeks, highlighting the ongoing risk of cardiovascular collapse even after delivery.3
During labour and delivery cardiac output is further increased, due to increased stroke volume as additional blood reaches the circulation with each uterine contraction, and also to a raised heart rate due to pain. Following delivery of the placenta there is a rapid rise in preload due to the venous return of blood to the maternal circulation, thus putting the woman with heart disease at risk of pulmonary oedema.
All women with known heart disease should be seen preconception by a cardiologist or obstetrician with an interest in heart disease in pregnancy, ideally in a joint clinic. Counselling should include the effects of pregnancy on the mother and fetus as well.
The risk of pregnancy to the mother with heart disease ranges from very low, similar to the general population—for example, in mild pulmonary stenosis or repaired atrial septal defect—to up to a 50% risk of life threatening cardiovascular event in pulmonary arterial hypertension. Siu et al2 looked at 599 pregnancies in women with heart disease and found that 13% were complicated by a cardiac event, most commonly pulmonary oedema, arrhythmia, stroke or cardiac death. Predictors of adverse maternal events are shown in Box 1. The impact of pregnancy on long term status should be discussed, including the possibility of a permanent deterioration in their functional status. Most studies to date, however, have only addressed the time until delivery or the early puerperium, so the long term effect of pregnancy on many cardiac conditions is unknown.
Box 1 Predictors of adverse maternal events (derived from Siu et al)4
New York Heart Association (NYHA) functional class >II
Cyanosis (SaO2 <90%)
Prior cardiovascular event
Systemic ventricular ejection fraction <40%
Left heart obstruction
Estimated risk of adverse event is 5%, 27% and 75% with 0,1 or >1 of these risk factors respectively.
Pre-pregnancy assessment of haemodynamic status and functional capacity with echocardiogram, exercise testing and, if indicated, cardiac catheterisation or magnetic resonance imaging (MRI), are recommended in moderate and high risk patients. It is important to be realistic with the prospective parents and, if pregnancy is deemed a very high risk, alternatives such as adoption or surrogacy should be discussed and appropriate advice about contraception given.
Maternal cardiac disease is associated with an increased risk of fetal complications such as prematurity, intrauterine growth retardation, and fetal loss.5 They are more likely to occur in the presence of maternal cyanosis, poor functional class, left heart obstruction, anticoagulation, smoking or multiple pregnancies.4 A further risk is recurrence of congenital heart disease in the offspring. For conditions with no chromosomal abnormality or family history, the recurrence rate is around 5%. However, it is as high as 50% in single gene disorders such as Marfan syndrome. If there is dysmorphism or a family history to suggest an underlying chromosomal or genetic abnormality, referral to a clinical geneticist is recommended.
In general, drugs known to be teratogenic should be stopped preconception or once pregnancy is confirmed and suitable alternatives should be commenced if necessary (Box 2).
Box 2 Cardiac drugs to avoid/use with caution
Angiotensin converting enzyme (ACE) inhibitors
Angiotensin II receptor antagonists
Timing of pregnancy
Medical or surgical intervention may be necessary before pregnancy to optimise cardiac function and minimise the risks of pregnancy. This may include optimisation of treatment of conditions such as hypertension, diabetes or arrhythmia, and surgical valve repair or replacement. The age of the woman with pre-existing heart disease should also be considered, as pregnancy is likely to be tolerated better if the mother is in her 20s rather than late 30s.
Pregnancy in specific conditions
It is the role of the obstetrician and the cardiologist to assess the potential risks from a pregnancy, thus allowing the mother to make an informed decision. There are some conditions, however, that should be considered prohibitively high risk with a ≥10% risk of maternal death. In these conditions women should be counselled against pregnancy (Box 3). In the case of an unplanned pregnancy or failure of contraception, termination of the pregnancy should be considered as an option.
High risk conditions
Despite medical advice, some women with these conditions do decide to continue with pregnancy and should be under the exclusive care of a specialist and multidisciplinary antenatal team. An outline of the management of these conditions in pregnancy is given below.
Pulmonary hypertension in pregnancy is associated with risk of maternal death of between 25–40%. Standard medical treatment includes oxygen therapy, diuretics and anticoagulation, but recently there have been case reports of successful pregnancy outcome with the use of targeted pulmonary vasodilators such as inhaled iloprost6 and intravenous prostacyclin,7 and referral should be made to a pulmonary hypertension centre in early pregnancy for consideration of these. A recent review of pregnancies in women with Eisenmenger syndrome showed that all deaths in this group occurred after delivery with a median time to death of 6 days postpartum.8 Thus, high dependency care is essential for several days postpartum due to the ongoing risk of cardiovascular collapse.
A normal aorta shows mild dilatation and an increased compliance in pregnancy due to a combination of the haemodynamic changes and hormonal influence. Aortic dissection can occur in previously apparently normal pregnant women, but women with a known aortopathy such as Marfan syndrome are at higher risk, the dissection occurring most commonly near term or postnatally. Meijboom et al9 demonstrated that patients with Marfan syndrome and an aortic root diameter at baseline of >4 cm are at risk of increased aortic dilatation during pregnancy and thus an increased risk of dissection and aneurysm formation. Any woman with Marfan syndrome who presents with chest or intrascapular pain in pregnancy should have urgent computed tomography (CT) or MRI of their aorta to exclude dissection. β-Blockers slow down the rate of aortic root dilatation and should be considered in all pregnant women with Marfan syndrome, especially those with a dilated root.
Severe aortic stenosis
Severe aortic stenosis is poorly tolerated in pregnancy due to the inability to increase cardiac output through the stenotic valve. This results in an increase in left ventricular pressure and an increased gradient across the stenotic valve, and women often develop symptoms for the first time during pregnancy. Medical treatment is aimed at decreasing heart rate with bed rest and β-blockade to increase time for left ventricular ejection and coronary filling. If the woman deteriorates despite medical treatment and the gestational age is not sufficient for delivery, intervention should be considered. The options are percutaneous balloon valvotomy, surgical valvotomy or valve replacement.
Systemic ventricular dysfunction
Ventricular dysfunction may be due to a pre-existing condition such as dilated cardiomyopathy or new onset peripartum cardiomyopathy. Standard heart failure should be used including oxygen, diuretics and vasodilators, but angiotensin converting enzyme (ACE) inhibitors should usually be withheld until after delivery due to the risk of renal impairment in the fetus. Thromboprophylaxis is essential due to the increased risk of thromboembolism.
Ischaemic heart disease
Acute myocardial infarction (AMI) is rare in pregnancy, with James et al10 estimating an incidence of 6.2/100 000 deliveries in North America between 2000 and 2002. However, pregnancy itself is an independent risk factor for AMI, increasing the incidence by three- to fourfold even in the absence of other risk factors,10 11 due to the altered haemodynamic situation plus a hypercoagulable state. Maternal deaths from IHD are increasing in the UK despite an overall drop in coronary deaths. This increased rate reflects the impact of lifestyle factors such as smoking and obesity. Techniques such as in vitro fertilisation are enabling older women to become pregnant which is an additional risk factor for pregnancy related AMI, with women >40 years being at a 30-fold greater risk compared with those <20 years.10 In the most recent UK maternal mortality data, all women who died from IHD had identifiable risk factors even though none had known pre-existing disease.1 As many of the risk factors are avoidable or modifiable, it stresses the importance of both identifying and addressing them preconception.
Prompt diagnosis and treatment of AMI is vital to reduce the morbidity and mortality of both mother and fetus. Unfortunately the diagnosis is often missed in pregnant women due to a low level of suspicion and a failure to recognise the symptoms or ECG changes by the obstetric team. Chest pain is also commonly reported in a normal pregnancy. Diagnosis is made by characteristic ECG changes and a rise in cardiac enzymes. Percutaneous coronary intervention is the treatment of choice for AMI in pregnancy and is the only effective treatment when the aetiology is coronary artery dissection. This should be performed before delivery as the risk of delivery with an untreated AMI is so high. Bare metal stents are preferable in pregnancy to drug eluting stents due to the lower risk of acute stent thrombosis. Ideally aspirin and clopidogrel should be continued for 6 weeks with clopidogrel later being stopped 1 week before delivery. If percutaneous coronary intervention is not available then thrombolysis should be considered. The majority of information regarding thrombolysis in pregnancy is gained from its use in pulmonary embolism, where it is associated with a maternal death rate of 1%12 and thus is considered to be reasonably safe.
Rheumatic heart disease
Rheumatic mitral stenosis accounts for nearly all cardiac maternal deaths in the developing world. Although rare in the UK rheumatic heart disease is still encountered, mainly in the immigrant population. There were two reported deaths from mitral stenosis, both in recently arrived immigrant women, in the most recent UK CEMACH report, the first UK deaths for more than a decade. Silversides et al13 reported cardiac complications in 35% of pregnancies in women with rheumatic mitral stenosis, most commonly pulmonary oedema and arrhythmias, and a worsening in functional class in 40%. The symptoms peak at around 20–24 weeks as the cardiac output and plasma volume peak. The transmitral gradient, already raised in mitral stenosis, is further increased by the tachycardia and high stroke volume leading to raised atrial pressures, dyspnoea and pulmonary oedema. The presence of atrial fibrillation or pulmonary hypertension will lead to further decompensation. The mainstay of treatment is bed rest, diuretics and rate control with β-blockers. Percutaneous balloon mitral valvuloplasty should be considered if symptoms persist despite medical treatment.
All women with rheumatic heart disease should be referred to a tertiary cardiac centre for assessment and a low index of suspicion should remain for all immigrant women who develop shortness of breath, palpitations or orthopnoea during pregnancy.
Palpitations are common during pregnancy with >50% of women experiencing ectopic beats or non-sustained arrhythmias.14 Ectopics and supraventricular tachycardias (SVT) may occur in a normal heart; however, atrial flutter or fibrillation and sustained ventricular arrhythmias suggest underlying heart disease and require thorough investigation. Pregnancy is associated with an increased risk and severity of arrhythmias due to the haemodynamic and hormonal changes and increased sympathetic drive. Women presenting with palpitations during pregnancy should have an accurate ECG diagnosis of the arrhythmia (this may require 24 h or longer ECG monitoring), assessment of any structural cardiac disease, and exclusion of underlying systemic disorders such as hyperthyroidism.
Many arrhythmias do not require pharmacological treatment but this should be initiated in the presence of severe symptoms or haemodynamic compromise. Drugs should be commenced at the lowest effective dose and concentrations should be monitored closely due to the altered pharmacokinetics and increased volume of distribution. Electrical cardioversion is safe throughout pregnancy and should be administered, with the woman in a left lateral position, for any arrhythmias compromising maternal and fetal circulation.
Both new and recurrent SVTs are encountered with increased frequency in pregnancy. Vasovagal manoeuvres should be attempted first, but if unsuccessful adenosine can be used safely in pregnancy. β-Blockers may be required in recurrent cases. β-Blockers are safe to use in pregnancy but require fetal growth monitoring and heart rate monitoring at delivery.
Atrial fibrillation and flutter
Atrial fibrillation and flutter are most commonly seen in structural or congenital heart disease. Digoxin and β-blockers may be used if drugs are required. Verapamil has been associated with a risk of significant fetal bradycardia although there are little data regarding this. If rapid conversion to sinus rhythm is not achieved then anticoagulation may need to be considered.
Ventricular tachycardia (VT)
Idiopathic VT is uncommon and usually arises from the right ventricular outflow tract with a left bundle morphology and inferior axis. VT associated with structural heart disease is associated with a significant risk of sudden death and should be promptly treated with electrical cardioversion, lidocaine or amiodarone. Potentially toxic drugs such as amiodarone should be avoided but may be required in refractory arrhythmias. Women with implantable defibrillators are able to have a successful pregnancy; one study involving 44 women with implantable defibrillators during pregnancy showed no increase in the number of shocks delivered or device complications.15
Bradycardias are much less common during pregnancy. Isolated congenital heart block with no symptoms does not require pacing either during pregnancy or labour. In the presence of symptoms or a dilated left ventricle a permanent pacemaker should be inserted with care to minimise radiation to the fetus.
Prosthetic valves and anticoagulation
Prosthetic valves can be either a bioprosthesis (including homografts, heterografts and autografts) or a mechanical valve. For women who require a valve replacement but would like to consider pregnancy in the future, a detailed discussion is needed to select the appropriate valve type. Factors to consider are durability of the valve, thromboembolic risk, need for anticoagulation, valve position, and fetal outcome. Bioprostheses have a low thromboembolic risk and thus avoid the need for anticoagulation, but they are at risk of structural valve degeneration necessitating further surgery. Conversely mechanical valves have much greater durability but are associated with a significantly higher risk of valve thrombosis, which is increased further in pregnancy due to the hypercoagulable state and is highest with single leaflet tilting disc mitral valves. They are also associated with an increased incidence of adverse fetal events and neonatal mortality secondary to mandatory anticoagulation use.16 The risk and benefits for each valve type is summarised in Box 4.
Box 4 Risks and benefits for prosthetic valve types
Low risk of thromboembolism
No need for anticoagulation
↑ rate of structural valve degeneration
Mechanical prosthetic valve
Superior haemodynamic profile
High risk of thromboembolism
Associated with fetal and neonatal complications
Warfarin is teratogenic (although the risks appear small in doses <5 mg,17) and is also associated with miscarriage, placental bleeding, and fetal intracerebral haemorrhage. Heparin does not affect the fetus as it does not cross the placenta due to its size, but is associated with an increased risk of thrombotic events compared with warfarin. This is due to difficulties in maintaining adequate anticoagulation, and events appear related to inadequate dosing and lack of monitoring.18 There is currently no consensus as to the most appropriate anticoagulation regimen during pregnancy, although all advocate heparin from week 36 to allow the fetus to metabolise warfarin before delivery. Different anticoagulation regimens are shown in Box 5. The long half life of low molecular weight heparin may allow better control of anticoagulation than unfractionated heparin, if used in conjunction with a haematologist and ensuring close monitoring of anti-Xa concentrations, maintaining values >1 with dose adjustment accordingly.
Box 5 Anticoagulation regimens in pregnancy with a prosthetic valve (adapted from Bates et al)19
Dose adjusted unfractionated heparin (UFH) throughout pregnancy (12 h subcutaneous)
Dose adjusted low molecular weight heparin (LMWH) throughout pregnancy
UFH or LMWH until week 13, warfarin until week 35, then LMWH or UFH until delivery
Consider adjunctive antiplatelet therapy to any of above regimens in 2nd and 3rd trimesters.
The risks and benefits to both mother and fetus of the possible anticoagulation regimens should be discussed with each woman.
Congenital heart disease
All women with congenital heart disease should be referred for specialist counselling pre-pregnancy or, if pregnant, as early as possible. As previously discussed there is a wide spectrum of risk ranging from that similar to the general population to prohibitively high risk as seen in pulmonary hypertension. A full review of congenital heart disease in pregnancy is out of the scope of this article but has been covered thoroughly in other reviews.20 21
Management of the pregnant woman
All women with heart disease deemed high risk for pregnancy should be managed in a specialised unit.22 There should be a dedicated multidisciplinary team with experience of managing heart disease in pregnancy, including an obstetrician, cardiologist, anaesthetist, haematologist, midwives, a neonatologist if the baby is considered at risk, and an adult intensivist in very high risk cases. The timing, place and mode of delivery should be planned well in advance in all moderate to high risk patients. This may require the woman delivering in a hospital at a considerable distance from home.
Delivery and postpartum care
The mode of delivery is generally determined by obstetric rather than cardiac indications; vaginal delivery with a low threshold for forceps assistance is preferable in most women. The exceptions to this are warfarin treatment within the last 2 weeks, Marfan syndrome, aortic aneurysm of any cause, and an acutely unwell mother.20 Vaginal delivery is generally associated with a lower risk of maternal and fetal complications with less blood loss, fewer rapid haemodynamic changes, and less risk of peripartum infection compared to caesarean section. There is a lack of prospective trial data on prophylactic antibiotic administration for infective endocarditis, but there is a strong case for giving antibiotics to high risk women undergoing procedures associated with significant or prolonged bacteraemia.23
Effective analgesia and anaesthesia is vital to limit the cardiac stress arising from contractions. Regional anaesthetic techniques such as spinal and epidural are the most commonly used in the UK for caesarean section, but do carry the risk of profound vasodilatation and hypotension due to autonomic paralysis. In high risk cardiac patients who require regional anaesthesia, slow and incremental dose epidural with invasive monitoring is advised as this carries a lower risk of cardiovascular collapse than spinal anaesthesia, due to the lower doses used. Specific contraindications to regional anaesthesia in cardiac disease include use of anticoagulation and severely limited or fixed cardiac output.
Monitoring during labour and delivery should be individualised with continuous ECG and intermittent blood pressures as a minimum. Invasive blood pressure and central venous pressure monitoring should be used in lesions where large or rapid fluid shifts are poorly tolerated, such as left sided obstructive lesions. Pulmonary artery catheters are rarely indicated.
The risk of cardiovascular decompensation remains after delivery due to the changes in circulating volume and elevated cardiac output, stroke volume and heart rate. This stresses the need for high risk patients to remain in an appropriate place where monitoring is possible, such as a high dependency unit, after delivery and not be immediately discharged to the general postnatal ward.
The number of women with both congenital and acquired heart disease becoming pregnant is increasing. Although heart disease is now the leading cause of maternal mortality and a cause of significant morbidity, the majority of women are able to have a successful pregnancy. Women with heart disease should be seen in a joint obstetric–cardiology clinic preconception for assessment of risk and optimisation of their clinical status, and should be managed by an experienced multidisciplinary team throughout pregnancy.
Due to the relatively small number of pregnancies in women with some cardiac conditions, there is a need for large multicentre studies looking at the long term impact of pregnancy on survival and clinical status to enable us to give an accurate assessment of the risks involved to all women with heart disease.
The majority of cardiac deaths in pregnancy occur in women with no previously diagnosed heart disease. Vigilance is needed to identify at risk patients for targeted antenatal and postnatal care. Deaths from ischaemic heart disease have seen the biggest increase and have now overtaken congenital heart disease as the leading cause of death in pregnancy. Obesity and smoking are major public health issues that should be addressed early in life to ensure that deaths from IHD—both during pregnancy and in the general population—do not continue to rise and reach epidemic proportions.
Key learning points
Heart disease is the leading cause of maternal mortality in the UK.
Deaths from IHD have shown the biggest increase and risk factors in women of childbearing age should be actively sought and modified before pregnancy.
All women with heart disease should have preconception counselling.
Appropriate contraceptive advice should be offered to women deemed high risk for pregnancy.
Moderate and high risk women should be managed by a specialist antenatal team.
Current research questions
What is the long term effect of pregnancy on different cardiac conditions?
What are the ways in which we can reduce the rising numbers of deaths from heart disease?
▶ Royal College Obstetrics Gynaecology. Saving mothers’ lives: reviewing maternal deaths to make motherhood safer. 7th report of the Confidential Enquiries into Maternal Deaths in the UK. London: CEMACH, 2007.
▶ Siu SC, Sermer M, Colman JM, et al. Prospective multicenter study of pregnancy outcomes in women with heart disease. Circulation 2001;104:515–21.
▶ Drenthen W, Pieper PG, Roos-Hesselink JW, et al. Outcome of pregnancy in women with congenital heart disease: a literature review. J Am Coll Cardiol 2007;49:2303–11.
▶ Thorne SA. Pregnancy in heart disease. Heart 2004;90:450–6.
▶ Task Force on the Management of Cardiovascular Diseases During Pregnancy of the European Society of Cardiology. Expert consensus document on management of cardiovascular diseases during pregnancy. Eur Heart J 2003;24:761–81.
Multiple choice questions (True (T)/False (F)); Answers after the references
1. In normal pregnancy
Haemodynamic changes peak during first trimester
Cardiac output increases by 50%
Systemic vascular resistance increases
Blood pressure decreases
Haemodynamic changes resolve within 1 week of delivery
2. Regarding maternal and fetal risk
Maternal risk is not increased in NYHA III
Women with severe PHT should be advised against pregnancy
Women with severe aortic stenosis should be managed in a specialised centre
Maternal cyanosis does not affect fetal outcome
Recurrence of congenital heart disease in the offspring is 20%
3. Regarding IHD in pregnancy
Pregnancy is an independent risk factor for AMI
Increasing maternal age does not increase the risk of AMI during pregnancy
Pregnancy is an absolute contraindication to thrombolysis
Primary PCI is the treatment of choice for AMI during pregnancy
Women who have AMI during pregnancy usually have identifiable risk factors
4. Regarding mitral stenosis in pregnancy
Symptoms peak towards the end of second trimester
It is more common in immigrant population
Dyspnoea arises due to a fall in transmitral gradient
Rate control with beta-blockers can improve symptoms
Balloon valvuloplasty is never indicated during pregnancy
5. The following are true regarding drugs in pregnancy
ACE inhibitors are safe in pregnancy
Fetal growth monitoring should be performed if beta-blockers are used
Warfarin should be avoided in the first trimester
LMWH may be used with mechanical valves but anti-Xa levels must be monitored
Warfarin may be used safely in the third trimester
6. The following are true regarding delivery and postpartum management in women with heart disease
Caesarean section is the mode of delivery of choice for women with heart disease
Slow and incremental dose epidural may be used in most high risk women
After delivery women with PHT can be managed on a general ward
Elective caesarean section should be performed if there is an aortic aneurysm
Effective analgesia is important to limit cardiac stress
(A) F; (B) T; (C) F; (D) T; (E) F
(A) F; (B) T; (C) T; (D) F; (E) F
(A) T; (B) F; (C) F; (D) T; (E) T
(A) T; (B) T; (C) F; (D) T; (E) F
(A) F; (B) T; (C) T; (D) T; (E) F
(A) F; (B) T; (C) F; (D) T; (E) T
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