Cardiac disease in pregnancy

Cardiac disease is the most common cause of indirect maternal death and the most common overall cause of death. Therefore, women with pre-existing cardiac disease and those who present with cardiac disease during pregnancy require specialist assessment and management during pregnancy, childbirth and the postpartum period.¹

Cardiovascular physiology during pregnancy²

Cardiac output needs to increase up to 50% during pregnancy, to enable the fetal circulation, and this increase starts already during the first trimester. There is a 30%–40% decrease in vascular resistance. As part of the cardiac output, plasma volume expands in the first and second trimester, followed by an increase in heart rate of around 10%–20%. Delivery further pushes these changes to a temporary maximum. After delivery, large fluid shifts are responsible for a transient volume overload in the first days post partum.

As a consequence of these haemodynamic changes, there is an increase in left ventricular end-diastolic dimensions, while the systolic measurements remain stable. The subsequent increase in stroke volume leads to a rise of the ventricular outflow tract velocity, and it mimics a hyperkinetic state. The expansion of stroke volume and lower afterload influence absolute regurgitation volumes, and regurgitant valve lesions will hardly be worse during pregnancy.

Hormonal changes influence the integrity of the vessel wall. The structure of the aortic wall may have a subtle weaker composition, which is not of significant importance to healthy women, but may enhance the risk of aortic dissection in women with aortic disease. Furthermore, pregnancy is known for its hypercoagulable state, which is very relevant in those with a mechanical prosthetic heart valve or Fontan circulation.

How common is cardiac disease in pregnancy? (Epidemiology)^{3 4}

In the Western world, the risk of cardiovascular disease in pregnancy has increased due to increasing age at first pregnancy. Hypertensive disorders are the most frequent cardiovascular disorders during pregnancy, occurring in 5–10% of all pregnancies.

Among the other disease conditions, congenital heart disease is the most frequent cardiovascular disease present during pregnancy in the western world. Rheumatic valvular disease dominates in non-western countries, comprising 56–89% of all cardiovascular diseases in pregnancy.

Risk factors for heart disease in pregnancy include a positive family history of cardiac disease, hypertension, smoking, obesity and increased age.

Peripartum intensive care unit (ICU) admissions are increasing in frequency, with affected women, who suffer from serious pre-existing conditions, are older, and present with multiple comorbidities and also congenital heart disease, being more frequently admitted than in previous years. Cardiomyopathies are rare, but represent severe causes of cardiovascular complications in pregnancy.

In 2017-19, cardiac disease remained the largest single cause of maternal deaths in the UK, with 36 deaths (1.66 per 100,000). The more common causes of maternal deaths include sudden arrhythmic death syndrome (SADS), cardiomyopathy, aortic dissection, coronary heart disease and myocardial infarction.

Pre-pregnancy counselling³

All women with known cardiac or aortic disease need informed maternal decision-making, and there is a clear need for individualised care. Especially in patients with a high-risk or possible contraindication for pregnancy, the risk of pregnancy and the necessity of careful planning of pregnancy should be discussed at a young age. However, many women can go through pregnancy with low-risks. All women with known cardiovascular disease should be referred for appropriate specialist assessment and advice.

For risk estimation, as a minimum, an electrocardiogram (ECG), echocardiography, and an exercise test should be performed. In case of aortic pathology, complete aortic imaging by computed tomography (CT) scanning or magnetic resonance imaging (MRI) is necessary for appropriate pre-conception counselling. Peak heart rate and peak oxygen uptake are both known to be predictive of maternal cardiac events in pregnancy. A pregnancy exercise capacity above 80% is associated with a favourable pregnancy outcome.

Aspects that must be discussed include long-term prognosis, fertility and miscarriage rates, risk of recurrence of congenital disease, drug therapy, estimated maternal risk and outcome, expected foetal outcomes, and plans for pregnancy care and delivery. A multidisciplinary management plan should be constructed and discussed with the patient. In addition, attention to risk factors including being overweight, smoking, and consuming alcohol is important, as these can have a clear impact on maternal and foetal outcomes. Pregnancy is a very suitable time for recommending a healthy lifestyle, including smoking cessation.

Sudden arrhythmic death syndrome

The case definition for SADS is a sudden unexpected cardiac death (ie presumed fatal arrhythmia) where all other causes of sudden collapse are excluded, including a drug screen for stimulant drugs such as cocaine.⁵

The physiological stresses of pregnancy and delivery are thought to bring out an underlying potential cardiac arrhythmia. Unfortunately these deaths are unpredictable.

See also the article on Sudden Cardiac Death in Young People.

Peripartum cardiomyopathy³

Important predisposing factors include multiparity, African ethnicity, smoking, diabetes, pre-eclampsia, malnutrition, advanced age, and teenage pregnancy.

The cause is uncertain, but potential aetiologies include inflammation and angiogenic imbalance, inducing vascular damage. The biologically active 16 kDa prolactin and other factors, such as soluble fms-like tyrosine kinase 1 (sFlt1), may initiate and drive peripartum cardiomyopathy.

Peripartum cardiomyopathy presents with heart failure secondary to left ventricular systolic dysfunction towards the end of pregnancy and in the months following delivery, with the majority diagnosed post-partum. It frequently present with acute HF, but also with ventricular arrhythmias and/or cardiac arrest.

Echocardiography is the imaging modality of choice. Initial left ventricular ejection fraction (LVEF) below 30%, marked left ventricular dilatation (LV end-diastolic diameter 6.0 cm or greater), and right ventricular involvement are associated with adverse outcomes.

Prospective studies have mainly focused on 6 month outcomes, reporting a mortality ranging from 2.0% in Germany to 12.6% in South Africa. Successful subsequent pregnancies, especially in patients with recovered ejection fraction, have been reported.

Acute coronary syndrome (ACS)

Myocardial infarction occurs more commonly in the later stages of pregnancy. Risk factors include smoking, increasing maternal age and diabetes. The presenting symptom is typically chest pain but atypical presentations may occur. See also the article on Acute Myocardial Infarction.

Treatment for acute coronary syndrome (ACS) in women during pregnancy is challenging. Current standard treatment includes coronary angioplasty with guideline-directed medical therapy including aspirin, P2Y12 inhibitors (antiplatelets), beta-blockers, and ACE inhibitors, which may cause adverse effects to the fetus. ACS increases ischaemic and obstetric complications.⁶

Aortic dissection⁷

Presentation

Pregnancy-associated aortic dissection is rare, with an incidence of 0.4 per 100,000. It occurs in association with severe hypertension secondary to pre-eclampsia, coarctation of the aorta, or connective tissue disease such as Marfan's syndrome. Symptoms can be non-specific (eg, chest pain, back pain, dyspnoea, syncope, and weakness on one side of the body), and they mimic common problems in pregnancy.

Investigations

The condition is diagnosed by computerised tomography or transoesophageal echocardiography.

Management

Management options include intrapartum repair of the dissection with support of cardiopulmonary bypass, postpartum repair, caesarean section, or vaginal delivery under regional anaesthesia. Choice will depend upon gestation and the vascular status of the mother.

Congenital heart disease⁸

Congenital heart disease is one of the most common congenital abnormalities.³ Deaths from congenital heart disease are uncommon.

Ideally, assessment should take place prior to pregnancy to see whether any surgical correction is required. In uncomplicated cases, no special treatment is required and the timing of delivery can be dictated by obstetric considerations.

See also the article on Congenital Heart Disease in Adults.

Pulmonary hypertension⁹

See also the separate Pulmonary Hypertension article.

The manifestations of pulmonary hypertension in pregnancy are very variable and non-specific. This rare disease can be extremely debilitating and can be associated with a poor overall prognosis.

Pregnancy in women with pulmonary hypertension puts them at an elevated risk because the physiological changes associated with pregnancy are not well endured leading to even higher morbidity and mortality. Right heart catheterisation remains the gold standard investigation. A mean pulmonary artery pressure of more than 20 mm of Hg is considered diagnostic.

Management includes phosphodiesterase 5 inhibitors (PDE5), calcium channel blockers and anticoagulation.

Valve disease^{10 11}

This is seen less frequently due to the reduction in rheumatic fever. However, stenosis is still common in immigrant communities. In the UK, calcific degeneration of congenital bicuspid aortic valves is the leading cause of stenosis encountered in pregnancy.

Stenosis poses more of a problem than incompetence, because the increased cardiac output is associated with heart failure and arrhythmias. All pregnant women should have antibiotics to reduce the risk of endocarditis. If anticoagulation is required, warfarin is considered to be the safest option.¹²

Mitral stenosis

See also the separate Mitral Stenosis article.

• The increase in the gradient between the left atrium and left ventricle is accentuated in pregnancy, leading to symptoms and signs of left heart failure, pulmonary oedema, arrhythmias and cardiovascular collapse. Atrial fibrillation may develop.

• Echocardiography can be used for diagnosis and to assess the patient's suitability for surgery.

• Bed rest, oxygen and diuretics may be required in the early stages. In severe cases, balloon mitral valvulotomy gives excellent results.¹³

Aortic stenosis

See also the separate Aortic Stenosis article.

• As with non-pregnant patients, the presenting features include angina, syncope and symptoms and signs of left and right heart failure. A diastolic murmur with opening snap may be heard.

• Echocardiographic estimation of valve area is the best investigation.

• Diuretics and vasodilators may be required to treat heart failure, pulmonary congestion and hypertension. Digoxin may be necessary to control atrial fibrillation. Symptomatic patients may require antenatal balloon valvuloplasty, open heart valve surgery, or valve replacement.

Aortic incompetence

See also the separate Aortic Regurgitation article.

• Acute regurgitation is caused by aortic dissection, bacterial endocarditis, or malfunction of a prosthetic valve. Chronic regurgitation is associated with bicuspid aortic valve or rheumatic heart disease.

• Acute regurgitation presents with cardiogenic shock and acute pulmonary oedema.

• Chronic regurgitation is usually tolerated well in pregnancy but advanced cases present with dyspnoea, chest pain and decreased exercise tolerance.

• Physical signs include a wide pulse pressure, brisk carotid pulse and mildly displaced apical impulse. An early diastolic murmur on the left sternal border and soft second heart sounds may also be heard.

• Transthoracic echocardiography and Doppler studies help to confirm the diagnosis and assess the severity of regurgitation.

• Acute aortic regurgitation is a surgical emergency that requires urgent valve replacement.

• Asymptomatic patients with chronic regurgitation only require monitoring.

• Mild symptoms respond to diuretics, hydralazine and nitrates. Patients with ventricular dysfunction may require digoxin. Surgical intervention is not usually required.

Mitral regurgitation

See also the separate Mitral Regurgitation article.

• The reduced systemic vascular resistance of pregnancy limits the effects of regurgitation. The condition is therefore normally tolerated well in pregnancy.

• In advanced disease, dilation of the left ventricle and atrium leads to elevation of pulmonary and arterial pressure.

• Symptoms include dyspnoea on exertion, orthopnoea and paroxysmal nocturnal dyspnoea. Left displacement of the apex and a pansystolic murmur are prominent signs.

• Doppler echocardiography to assess the structure of the valve and the size of the left ventricle and measurement of the pulmonary arterial pressure are the most contributory investigations.

• Hydralazine, diuretics and digoxin should be given when systolic function is impaired. In severe cases, mitral valve repair may be required, with valve replacement used as a last resort.

Other valve disease

Pulmonary valves and tricuspid valves can also be involved, usually along with mitral valve disease. Left ventricular failure is rare but post-exertion syncope and angina can appear for the first time in pregnancy, especially during the last trimester.

Prevention of cardiac disease in pregnancy

The haemodynamic strain associated with cardiac disease in pregnancy may mask a pre-existing condition (eg, rheumatic heart disease) or a pregnancy-associated cardiac complication may develop (eg, cardiomyopathy).

Most patients will present for the first time to obstetricians or GPs, not to cardiologists. Early diagnosis is important but can be challenging because symptoms and signs (eg, fatigue, shortness of breath, oedema and systolic ejection murmurs) can mimic the physiological changes of pregnancy.

A low threshold of referral to a cardiologist should therefore be maintained.¹⁴

Women with pre-existing heart disease should have specialist preconceptual counselling as well as advice about the use of appropriate contraception.

See also Cardiovascular Risk Assessment and Prevention of Cardiovascular Disease.