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Heart disease in pregnancy

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Highlights

  • Cardiac disease is the leading cause of maternal mortality in the developed world.

  • Most deaths occur in women who are not known to have heart disease before pregnancy.

  • Clinicians caring for pregnant women must be aware of the presentation and causes of cardiac disease.

  • There must be a low threshold for investigation of women with possible cardiac symptoms and referral to Cardiology.

  • Expert joint cardiac and obstetric pre-pregnancy and antenatal management are key to improving outcomes.

Cardiac disease is the leading cause of maternal mortality in the developed world. The majority of women with heart disease are able to successfully undergo pregnancy. However, in women with severely impaired ventricular function, severe left heart obstruction, pulmonary hypertension and aortopathy, such as Marfan syndrome, with significant aortic dilatation, pregnancy is associated with a significant risk, and these women should be counselled against pregnancy if there is no option for treatment that reduces risk. Although there are increasing numbers of women with congenital heart disease who are considering pregnancy, as a result of joint expert specialist cardiac and obstetric care, maternal mortality is low. Most of the observed mortality occurs in women with structurally normal hearts who were not known to have heart disease before their pregnancy. It is therefore important that those caring for pregnant women are aware of the risk factors for and presentation of cardiac conditions in pregnancy. We review the presentation and management of both congenital and acquired heart diseases in pregnancy.

Introduction

In the developed world, good antenatal and obstetric care has greatly reduced maternal mortality due to obstetric causes, and cardiac disease has now emerged as the leading cause of maternal mortality ∗[1], ∗[2] (Fig. 1). Of concern, the most recent ‘Saving Mothers’ Lives' report covering maternal mortality in the UK shows that whilst overall maternal mortality in the UK is low and continues to fall, deaths due to cardiac disease have risen ∗[1], ∗[2].

The most recent UK maternal mortality review for which details of cardiac deaths are available is for 2006–2008 [1]. The majority of deaths occurred in women with structurally normal hearts, many of whom were not known to have heart disease prior to pregnancy: their disease was revealed or precipitated by the hormonal and haemodynamic changes associated with pregnancy. Importantly, care was deemed to be substandard in >50% of the cardiac deaths, and in half of these cases better care may have resulted in a different outcome. The increase in cardiac mortality found between 2006 and 2008 is likely to be a reflection of the changing demographics of the overall obstetric population with increasing maternal age, obesity and smoking. All the women who died from ischaemic heart disease had at least one identifiable risk factor. The detailed review of the cases in the report identified the importance of having a low threshold for investigation and cardiological review of women who present with possible cardiac symptoms during pregnancy or the post-partum period; therefore, investigations should not be withheld because of pregnancy.

Although the numbers of patients with congenital heart disease surviving into their childbearing years are continuing to increase, and many have complex conditions, the maternal mortality in these patients continues to fall, and it accounted for only three out of the 53 cardiac deaths over the report period 2006–2008. Patients with congenital heart disease are generally under regular cardiology follow-up, and the low mortality is a testament to good pre-pregnancy counselling and the importance of the multidisciplinary team in providing joint cardiac obstetric care.

The increased haemodynamic demands of pregnancy are significant, and they start early: cardiac output rises by 50% by the middle of the second trimester, and it must be maintained throughout the rest of the pregnancy (Fig. 2) [3]. Any condition that limits the ability to increase cardiac output will result in pregnancy being poorly tolerated. During labour, cardiac output increases further due to increased heart rate from pain and anxiety, and uterine contractions returning blood to the venous system. Blood pressure and oxygen requirements also rise during contractions. Following delivery, uterine and placental auto-transfusion and release of caval compression result in a significant increase in the venous return. The changes associated with pregnancy can take several weeks to return to normal. Patients with impaired ventricular function therefore remain at risk for several weeks after delivery, and many cases of pregnancy-associated cardiomyopathy are not revealed until several weeks later.

In addition to the circulatory changes, a variety of hormonal changes to facilitate tissue relaxation also occur. These changes may also contribute to the observed increased risk of aortic and coronary artery dissection during pregnancy and the post-partum period.

Patients with heart disease should be offered specialist joint cardiac and obstetric preconception assessment and counselling. This assessment should address both the maternal and foetal risks (Table 1, Table 2).

Different scoring systems have been developed to assess the risk of adverse maternal outcomes during pregnancy. The factors consistently predictive of morbidity are pre-pregnancy poor ventricular function, arrhythmia or cardiac event, poor functional class (New York Heart Association (NYHA) class II or more) and left heart obstruction. Further, these risks are additive, as reflected in the Cardiac Disease in Pregnancy (CARPREG) scoring system [4] (Table 3). The ZAHARA investigators reviewed this in patients with congenital heart disease, and they identified additional predictors [5] (Table 3). Maternal risk may also be classified by lesions [6] (Table 4). Severe systemic ventricular impairment, previous peripartum cardiomyopathy with residual ventricular impairment, severe left heart obstruction, pulmonary arterial hypertension (PAH) of any cause and Marfan syndrome or other aortopathy with aorta >40 mm are associated with a significant risk of mortality, and women with these conditions should be advised that pregnancy would be associated with a high risk of morbidity and mortality. Any treatment to reduce pregnancy risk should be considered, and effective contraception should also be discussed as well as alternatives to pregnancy.

Further evaluation to determine the haemodynamic significance of valvular lesions and ventricular function may be required, and cardiopulmonary exercise testing, exercise echocardiography, specialised cardiac imaging and cardiac catheterisation should be considered. Haemodynamically significant valve lesions may require intervention prior to pregnancy.

Exercise echocardiography can refine risk stratification for some women with significant disease who wish to conceive, for example, the asymptomatic woman with severe aortic stenosis (valve area ≤1 cm2) and good ventricular function. Such a patient is likely to tolerate pregnancy well if she has a normal exercise capacity, normal blood pressure response to exercise, no exertional electrocardiographic (ECG) changes, the increase in Doppler-derived aortic valve gradient at peak exercise is <18 mm Hg, left ventricular ejection fraction increases on exercise (indicating contractile reserve) and there is no exercise-induced PAH (estimated pulmonary artery systolic pressure <60 mm Hg). Conversely, pre-pregnancy aortic valve replacement should be considered if exercise capacity and the pressor response to exercise are reduced, there are exertional ECG changes, exercise is associated with no increase in the left ventricular ejection fraction, there is a rise in Doppler-derived aortic valve gradient of >20 mm Hg or pulmonary artery systolic pressure rises to ≥60 mm Hg [7]. Women with impaired ventricular function should also be made aware that ventricular function may deteriorate with pregnancy and may not fully recover.

Women with aortopathy and aortic dilatation >40 mm should be considered for prophylactic surgery, and care should be discussed with an aortic multidisciplinary team. It is important to remember that prophylactic aortic root replacement does not eliminate the risk of dissection in the descending aorta.

Many drugs have potential teratogenic effects, and therefore medication should also be reviewed prior to pregnancy (Table 5).

Section snippets

Ventricular dysfunction

Pregnancy places a prolonged stress on the cardiovascular system, and heart failure is an important cause of morbidity as well as mortality. With improvements in medical care, increasing numbers of women with impaired ventricular function are well enough to consider pregnancy. Ventricular impairment may be due to congenital heart disease, previous chemotherapy, cardiomyopathy or ischaemic heart disease. However, ventricular impairment often presents for the first time during pregnancy or the

Conditions that present with chest pain

There should be a low threshold for early cardiology referral of pregnant patients with chest pain – the failure to do so has contributed significantly to cardiac death being the most common cause of maternal mortality.

Native valvular disease

Valvular disease may present for the first time during pregnancy. Stenotic lesions that limit the ability to increase cardiac output may not be well tolerated during pregnancy and delivery. Regurgitant lesions are generally better tolerated.

Women with severe valve disease and who wish to consider pregnancy require careful multidisciplinary discussion and counselling. If valve repair is not possible and replacement is required, then several factors need to be considered when making an

Arrhythmias

Palpitation is a common symptom during pregnancy, and it is often due to atrial and ventricular ectopics. Sustained symptoms or associated symptoms of dizziness, breathlessness, chest pain or pre-syncope suggest a tachyarrhythmia, and they should be investigated promptly. Both ectopics and tachyarrhythmias are more common during pregnancy because of the increased circulating plasma volume and associated atrial stretch. Atrial and ventricular ectopics are benign, and they require no treatment;

Congenital heart disease

All patients with congenital heart disease who are considering pregnancy should receive pre-pregnancy counselling with a specialist joint congenital cardiac and obstetric team, and those considered medium and high risk should be managed by the specialist team.

The outlook for patients born with congenital heart disease has transformed over the last three decades, and now around 85% will survive into adulthood even with complex conditions. Therefore, there are now many women with congenital heart

Pulmonary arterial hypertension

PAH defined as a mean pulmonary artery pressure >25 mm Hg is associated with up to 50% risk of maternal mortality in pregnancy [38]. With targeted pulmonary vasodilator therapies such as inhaled iloprost or intravenous prostacyclin, there has been some improvement, but mortality still remains up to 33% [39]. Death is often sudden a few days after delivery, and it occurs due to the combination of an increase in systemic vascular resistance limiting cardiac output, thrombosis of distal pulmonary

Anticoagulation

All anticoagulation regimes are associated with significant maternal and foetal risks. It is therefore important that the reason for anticoagulation, the risks associated with different pharmacological regimes and the practical requirements for compliance with monitoring are discussed to allow women to make an informed choice about what balance of risks she chooses to accept.

Anticoagulation may be achieved using either warfarin or heparin. Warfarin crosses the placenta, and it can cause foetal

Peripartum period

Warfarin crosses the placenta resulting in an anticoagulated foetus, and therefore patients taking warfarin should be switched to LMWH after 36 weeks. Delivery, either by induction of labour or by caesarean section, should be planned in order to minimise the risk of bleeding. One management regime for the peripartum period is outlined in Fig. 3 [40].

Delivery planning

Most women with heart disease are able to have a normal vaginal delivery. Some with more complex conditions may require closer monitoring and delivery in a particular centre, and therefore delivery may need to be planned for geographical reasons, as is the case for patients with anticoagulation and those requiring elective caesarean section. During the later stages of pregnancy, it is helpful to consider a delivery plan. Factors to consider include the mode and timing of delivery, the

Post-partum

There are several issues to consider in the post-partum period. The haemodynamic changes take several weeks to resolve, and therefore heart failure may not present until after delivery. Those at the highest risk should be under observation in the hospital for at least 48 h. Early cardiology follow-up is also important for patients with impaired ventricular function and those with valvular disease, which may have deteriorated with pregnancy. Cardiac medications, anticoagulation and contraception

Conclusion

Cardiac disease is the leading cause of maternal mortality. Most of the mortality occurs in women who are not known to have cardiac disease. There should be a low threshold for investigation of chest pain. Most women with heart disease, however, are able to have a pregnancy successfully, and indeed they should not be unnecessarily discouraged. Adverse outcomes can often be avoided with a specialist multidisciplinary team management.

Practice points

  • Any woman who develops severe chest pain during

Conflict of interest

The authors confirm that there are no conflicts of interest.

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