Cardiac Disease In Pregnancy

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
• Changes in demography have also resulted in an increase in incidence in areas where there are large immigrant communities. One study in West London found that of 139 women referred for evaluation of a heart murmur in pregnancy, 97% were found to have a physiological murmur and only 4 patients had significant new conditions. 3 out of the 4 women were immigrants with no previous history of heart disease.²
• The tendency to postpone motherhood until the third decade is having an effect.³

The report of confidential enquiries into maternal and neonatal deaths in the United Kingdom 2000-2002 reported a total of 44 deaths due to heart disease in pregnancy.⁴ This is nine deaths more than the previous report covering 1997-99 and makes cardiac disease the commonest indirect cause of maternal death after psychiatric causes, It is more common than the most frequent direct cause, which is thromboembolism. For the years 2000-2002 the maternal mortality rate was 2.2/100,000 pregnancies. The review of maternal deaths 2003-2005 reported that cardiac deaths was the commonest cause of deaths overall and was probably due to the rising incidence of lifestyle-related heart disease. 48 deaths from cardiac causes were reported during that period.⁵

Risk factors

Risk factors for heart disease in pregnancy include a positive family history of inherited cardiac disease, hypertension, obesity and increased age. The latter is becoming an important factor, as more women in older age groups seek assisted conception.⁴

The last 50 years has seen a dramatic reduction in rheumatic heart disease but is still seen in immigrant communities and in developing countries. Peripartum cardiomyopathy, myositis and myocardial infarction were the commonest causes of maternal cardiac deaths in 2000-2002, closely followed by aneurysm of the thoracic aorta and its branches. These conditions accounted for over half of all maternal cardiac-related deaths. Pulmonary hypertension was a significant cause, especially Eisenmenger's syndrome secondary to congenital heart disease. This is commonly secondary to a congenital disorder such as an atrial septal defect causing a left-to-right shunt, pulmonary hypertension and eventual reversal of the shunt into a right-to-left shunt.) It has a high mortality.⁴

The following should be elucidated 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 non-specific and often present in healthy pregnant women but a high index of suspicion is the safest course.⁶ See individual conditions for other presenting symptoms.

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

• 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.

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 1:1500 to 1:4000 live birth. 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 chest Xray 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.⁸ Endomyocardial biopsy may be required in cases of diagnostic difficulty.
• Treatment
  • 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. ACE inhibitors are feto-toxic but are the mainstay of treatment post-partum.
  • Patients are at high risk of thromboembolism and anticoagulation should be considered.⁹
  • 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 The condition is rare but accounts for 50% of aortic dissection in women under 40. It occurs in association with severe hypertension secondary to pre-eclampsia, coarctation of the aorta, or connective tissue disease such as Marfan's. 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 trans-oesophageal echocardiography.
• Treatment Management options include intra-partum repair of the dissection with support of cardio-pulmonary bypass, post-partum repair, Caesarian section, or vaginal delivery under regional anaesthesia. Choice will depend upon gestation and the vascular status of the mother.

Congenital heart disease

• Presentation Congenital heart disease 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 tetralogy of Fallot 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 are suspected.
• Treatment 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

• Presentation Primary pulmonary hypertension is rare. It is defined clinically by a persistently elevated pulmonary artery pressure (PAP), mean pressure >25 mm Hg at rest, without an obvious aetiology. Secondary pulmonary hypertension is much commoner and is associated with atrial and septal defects, mitral valve disorders and many non-cardiac causes. Symptoms include dyspneoa 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 left sternal border and a right-sided fourth heart sound.
• Investigation 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.
• Treatment 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 disease¹⁰

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.¹¹

Mitral stenosis

• Presentation 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.
• Investigations Echocardiography can be used for diagnosis and to assess the patient's suitability for surgery.
• Treatment Bed rest, oxygen and diuretics may be required in the early stages. In severe cases, balloon mitral valvulotomy gives excellent results. There is evidence that this is preferable to open heart valve surgery (commissurotomy).¹²

• Presentation 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.
• Investigations Echocardiographic estimation of valve area is the best investigation.
• Treatment Diuretics and vasodilators may be required to treat heart failure, pulmonary congestion and hypertension. Digoxin may be necessary to control atrial fibrillation.¹³ Symptomatic patients may require antenatal balloon valvuloplasty, open heart valve surgery, or valve replacement.

• Presentation Acute incompetence is caused by aortic dissection, bacterial endocarditis, or malfunction of a prosthetic valve. Chronic incompetence is associated with bicuspid aortic valve or rheumatic heart disease. Acute incompetence presents with cardiogenic shock and acute pulmonary oedema. Chronic incompetence 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.
• Investigation Transthoracic echocardiography and Doppler studies help to confirm the diagnosis and assess the severity of incompetence.
• Treatment Acute incompetence is a surgical emergency that requires urgent valve replacement. Asymptomatic patients with chronic incompetence only require monitoring. Mild symptoms responds to diuretics, hydralazine and nitrates. Patients with ventricular dysfunction may require digoxin. Surgical intervention is not usually required.

• Presentation With incompetence, 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.
• Investigations 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.
• Treatment 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.¹⁴

The confidential enquiry into maternal deaths report for 2000-2002 found that the majority of maternal deaths occurred in women with previously undiagnosed heart disease. The haemodynamic strain associated with pregnancy may mask a pre-existing condition (e.g. rheumatic heart disease) or a pregnancy-associated cardiac complication may develop (e.g. 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 (e.g. 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.³

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

High risk of maternal mortality is associated with:

• Pulmonary hypertension
• Severely depressed systemic ventricular function (ejection fraction <30%)
• Severe left heart obstruction
• Marfan syndrome with ascending aorta >40 mm
• Peripartum cardiomyopathy with residual impairment of left ventricular function

Women with significant risk include those with:

• Cyanotic heart disease
• Other complex congenital heart disease including Fontan circulation (which results from a single ventricle anomaly) and systemic right ventricle (a right ventricle supporting the systemic circulation either due to congenital anomaly or surgery)
• Mechanical prosthetic valves