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.

Epidemiology

Cardiac disease in pregnancy is becoming more common. There are several reasons for this:

• Due to better care, women with congenital cardiac disease are surviving to reproductive age.^[1]
• The tendency to postpone motherhood until the third decade is having an effect.^[2]

The report of confidential enquiries into maternal and neonatal deaths in the UK 2006-2008 reported a total of 53 deaths due to heart disease in pregnancy.^[3] The number in the previous triennium was 48. The rate for indirect maternal deaths was 6.72/100,000 pregnancies and, within that, the rate for cardiac disease was 2.31 per 100,000 maternities. Therefore, cardiac disease is the most common cause of indirect maternal death and the most common overall cause of death.

Risk factors

Risk factors for heart disease in pregnancy include:

• A positive family history of inherited cardiac disease.
• Hypertension.
• Obesity.
• Increased age.

The last factor listed above is becoming important as more women in older age groups seek assisted conception.

Aetiology^[3]

Sudden arrhythmic death syndrome (SADS) was the most common cause of maternal cardiac death in 2006-2008 (10 deaths), closely followed by cardiomyopathy (9 deaths).

Other leading causes were aortic dissection, coronary heart disease and myocardial infarction. Deaths from pulmonary hypertension and from congenital heart disease continue to decrease. Over a period of 50 years there has been a dramatic reduction in rheumatic heart disease but it is still seen in immigrant communities and in developing countries. However, there were no deaths from rheumatic heart disease in this last triennium.

What to look for at booking or later in pregnancy

The recommendations of the last Centre for Maternal and Child Enquiries (CMACE) report state that:^[3] "There must be a low threshold for further investigation of pregnant or recently delivered women who complain of chest pain that is severe, or radiates to the neck, jaw or back, or is associated with other features such as agitation, vomiting or breathlessness, tachycardia, tachypnoea, orthopnoea or acidosis. This is especially important for women who smoke, are obese or who have hypertension."

History

The following should be discussed at the booking clinic:

• A past history of congenital or acquired heart disease.
• A family or personal history of congenital heart disease.
• A history of hypertension.
• A history of breathlessness, fatigue or oedema.

The symptoms of incipient de novo heart disease are nonspecific and often present in healthy pregnant women but a high index of suspicion is the safest course. See individual conditions for other presenting symptoms.

Signs

It should be remembered that physiological changes to the haemodynamic status in pregnancy may alter the presentation of a variety of cardiac conditions.

NB: murmurs - one study of 199 healthy pregnant women found that 93.2% had a systolic murmur at some time during their pregnancy. They are invariably systolic, may be early, mid or late and there may be a diastolic component. They are located predominantly at the second left intercostal space or along the left sternal border, although they may radiate widely. They may occur at any stage in pregnancy and may come and go.

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.^[4]

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

Puerperal cardiomyopathy and myositis

Presentation

This is also known as peripartum cardiomyopathy as it can present one month before, as well as five months after, delivery. The incidence is 1:1,500 to 1:4,000 live births.

Risk factors include older age, greater parity, black race and multiple gestations. Viral myositis has been implicated in the aetiology. Dyspnoea, fatigue and ankle oedema can present in both late pregnancy and cardiomyopathy but nocturnal dyspnoea, nocturnal cough and chest pain are symptoms that should raise suspicion. Signs may include new regurgitant murmurs, pulmonary crackles, elevated jugular venous pressure and hepatomegaly.

Investigations

• ECG may show left ventricular hypertrophy and CXR invariably shows cardiomegaly. Echocardiography demonstrates recent left ventricular dysfunction.
• Cardiac MRI is a safe and non-invasive procedure which can help with both diagnosis and prognosis.^[5]
• Endomyocardial biopsy may be required in cases of diagnostic difficulty.

Management

• Salt restriction should be instituted and diuretics prescribed to relieve pulmonary oedema.
• Vasodilators such as hydralazine, nitrates or amlodipine should be given to reduce afterload in the presence of ventricular dysfunction. Angiotensin-converting enzyme (ACE) inhibitors are fetotoxic but are the mainstay of treatment postpartum.
• Patients are at high risk of thromboembolism and anticoagulation should be considered.^[6]
• The timing of delivery should be dictated by obstetric considerations.

Myocardial infarction

Presentation

The incidence is 1 in 10,000 deliveries. The condition occurs more commonly in the later stages of pregnancy. Risk factors include smoking, increasing maternal age and diabetes. The presenting symptom is chest pain.

Investigations

ECG may be normal or equivocal but troponin level will usually be raised. Early coronary angiography is indicated.

Management

The majority of patients do not have increased risk factors. The causative mechanism is often coronary artery dissection, involving a mechanism similar to aortic dissection. 20% of women have intracoronary thrombus or arteriosclerosis on angiography.

• Treatment involves coronary artery stenting and coronary artery bypass graft.
• Tissue plasminogen activator (TPA) is another option. It does not cross the placental barrier so does not cause fetal problems but should be avoided in the early puerperium as it increases the risk of haemorrhage.

Aortic dissection

Presentation

Aortic dissection is rare. It occurs in association with severe hypertension secondary to pre-eclampsia, coarctation of the aorta, or connective tissue disease such as Marfan's syndrome. The presenting symptoms are chest pain or interscapular pain, associated with end-organ ischaemia, acute heart failure, aortic incompetence, or haemopericardium with tamponade.

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 disease^[7]

Congenital heart disease is one of the most common congenital abnormalities and the prevalence of this condition in pregnancy is about 0.8%.^[8] Deaths from congenital heart disease are uncommon.

Presentation

Grown-up congenital heart disease (GUCHD) is likely to be identified whilst taking the history. Undetected congenital disease may be missed unless cyanosis develops. Acyanotic conditions, such as atrial and ventricular septal defects or persistent ductus arteriosus, usually cause no increased maternal or fetal risk. Likewise, cyanotic conditions such as Fallot's tetralogy that have been repaired surgically usually cause no problems. The main problems arising from congenital heart disease are due to pulmonary hypertension or Eisenmenger's syndrome.

Investigation

Fetal echocardiography should be used after 20 weeks to detect fetal heart defects in a mother with congenital heart disease. No other investigations are required unless pulmonary hypertension or Eisenmenger's syndrome is suspected.

Management

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.

Pulmonary hypertension

See also the separate Pulmonary Hypertension article.

Presentation

Primary pulmonary hypertension is rare. It is defined clinically by a persistently elevated pulmonary artery pressure, mean pressure >25 mm Hg at rest, without an obvious aetiology. Secondary pulmonary hypertension is much more common and is associated with atrial and septal defects, mitral valve disorders and many non-cardiac causes. Symptoms include dyspnoea on exertion, syncope on exertion, fatigue, lethargy and chest pain. Less common symptoms include cough, haemoptysis and hoarseness. Signs include loud second heart sounds, a systolic ejection murmur heard over the left sternal border and a right-sided fourth heart sound.

Investigations

Echocardiography will demonstrate evidence of right heart failure. Diagnosis can be confirmed by ventilation perfusion scans, computed tomographic pulmonary angiography or right heart catheterisation and digital subtraction.

Management

Options are designed to promote pulmonary vasodilation and include oral nifedipine or parenteral prostacyclin and nitric oxide, The patient should be anticoagulated to reduce the risk of thromboembolism. Premature spontaneous delivery is common but, if this does not happen, delivery should be planned for 32-34 weeks.

Valve disease^{[1, 9]}

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.^[10]

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.^[11]

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

The haemodynamic strain associated with 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.^[2]

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