About 70-80% of children with congenital heart disease (CHD) now reach adult life (16 years and over) and thus reproductive age. Unfortunately, there is still a significant mortality rate among young adults with corrected CHD. In the pregnant population, cyanotic CHD is associated with a higher maternal and fetal morbidity and mortality than non-cyanotic disease, but both groups of women should be regarded as high-risk patients.
Problems and special considerations
Patients primarily with disorders of cardiac output may experience cardiac failure as pregnancy progresses, because of the increased demands placed on the cardiovascular system and the increased oxygen demand. Patients with cyanotic (or potentially cyanotic) disorders may experience worsening cyanosis as the decreasing systemic vascular resistance encourages shunting of blood across the heart; this is compounded by increased oxygen demand. Both types of patients are prone to arrhythmias and venous thromboembolism, and tolerate hypovolaemia poorly.
A maternal haematocrit of greater than 60%, arterial oxygen saturation of less than 80%, right ventricular hypertrophy and episodes of syncope are all considered poor prognostic factors. Women with cyanotic disease have higher rates of spontaneous abortion, and these are said to correlate with haematocrit.
The World Health Organization (WHO) classification of pregnancy risk depending on cardiac condition is given in Table 98.1.
Regardless of the maternal cardiac condition, the fetus of the mother with CHD has an increased risk of CHD (Table 98.2). Other fetal risks include prematurity, fetal growth restriction and perinatal death.
Bolus doses of oxytocin cause a transient but sometimes profound fall in arterial blood pressure; the drug should be given by intravenous infusion if at all. Ergometrine causes a sharp rise in arterial, central venous and intracranial pressures and should generally be avoided in women with CHD, although it may be preferable to oxytocin in certain fixed-output states without pulmonary hypertension. If caesarean section is performed, the need for oxytocics may be avoided by performing a brace suture through the uterus to provide mechanical, rather than pharmacological, uterine compression.
Women may be receiving therapeutic doses of anticoagulants and this may preclude regional analgesia and anaesthesia, though the latter is still possible if timed appropriately.
Table 98.1 Modified WHO classification of maternalrisk by cardiac condition
|
WHO pregnancy risk |
|
|
1: Risk no higher than general population |
2 or 3: Increased risk of 4: Pregnancy contraindicated: maternal mortality and very high risk of maternal morbidity mortality or severe morbidity |
|
Uncomplicated, small or mild: |
WHO 2 if well: Previous peripartum • unoperated atrial cardiomyopathywith any |
|
• pulmonary stenosis • ventricular septal defect • patent ductus arteriosus • mitral valve prolapse |
septal defect residual impairment of left ventricular function • repaired tetralogy of Fallot Severe systemic ventricular • most arrhythmias dysfunction (NYHA III-IV or LVEF < 30%) WHO 2/3 depending on patient- Pulmonary arterial hypertension |
|
Successfully repaired |
• mild left ventricular Severe left heart obstruction |
|
simple lesions, e.g.: • ostium secundum atrial septal defect • ventricular septal defect • patent ductus arteriosus • total anomalous pulmonary venous drainage |
impairment Marfan’s syndrome with aorta • hypertrophic dilated > 40 mm cardiomyopathy • native or tissue valvular heart disease • Marfan’s syndrome without aortic dilatation • heart transplantation WHO 3: |
|
Isolated ventricular extrasystoles and atrial ectopic beats |
• mechanical valve • systemic right ventricle • Fontan circulation • cyanotic heart disease |
LVEF, left ventricular ejection fraction; NYHA, New York Heart Association.
Adapted from: Thorne S, MacGregor A, Nelson-Piercy C. Risks of contraception and pregnancy in heart disease. Heart 2006; 92: 1520-5.
Management options
Women with CHD must be identified early in pregnancy (preferably seen for preconception counselling) and managed jointly by the obstetrician, cardiologist and obstetric anaesthetist. Appropriate investigations and plans should be instituted (see Chapter 91, Cardiovascular disease) and placed clearly in the patient’s notes. Some units have a register in which high-risk patients approaching term delivery can be entered. The anaesthetists involved should have a clear understanding of the underlying cardiac lesion and/or correction, and its implications for cardiac output and likely complications that may be encountered.
Table 98.2 Risk of neonatalcardiac lesions when at least one parent has congenital heart disease
|
Tetralogy of Fallot |
2-3% |
|
Persistent ductus arteriosus; aortic coarctation |
4% |
|
Atrial septal defect |
5-11% |
|
Pulmonary stenosis |
6-7% |
|
Ventricular or atrioventricular septal defect |
10-16% |
|
Aortic stenosis |
15-18% |
|
Marfan’s/Di George’s syndrome |
50% |
Caesarean section is not indicated for women with CHD unless there are obstetric indications or worsening maternal condition. Concerns regarding caesarean delivery include the haemodynamic response to anaesthesia, the risk of increased blood loss, and the increased risk of postoperative complications such as bleeding and infection. Planned induction of labour may appear to have obvious benefits, but carries the risk of an increased likelihood of obstetric intervention. Elective instrumental delivery avoids the fall in cardiac output that accompanies pushing, and should be recommended for most cases, although a maximum of 15-30 minutes’ pushing can be allowed for mild cases. The left lateral position is often advised for examinations and labour to avoid aortocaval compression.
Invasive arterial and/or central venous pressure monitoring is generally recommended except for mild conditions; the use of pulmonary artery catheters is controversial and is usually impractical outside the intensive care unit.
Depending on the lesion and repair, there may be increased risk of a paradoxical embolism; all intravenous injections must be administered with care, and a loss-of- resistance to saline technique is advisable if epidural anaesthesia is employed.
Cautious use of low-dose epidural bupivacaine (0.1% or less) in combination with an opioid (usually 2.0-2.5 pg/ml fentanyl) provides optimal analgesia for women with CHD. Intrathecal opioids and continuous spinal analgesia have also been used. The use of high concentrations of bupivacaine (0.25%) in labour is contraindicated because of the risk of rapid and uncontrolled decrease in cardiac output.
Anaesthesia for caesarean delivery in women with CHD carries high risks. The options are for slow induction of regional anaesthesia (e.g. epidural, continuous spinal or combined spinal-epidural with a very small spinal component) or a ‘cardiac’ general anaesthetic (which may necessitate prompt neonatal resuscitation and some hours of maternal and neonatal postoperative ventilatory support). There are no absolute rules; the relative risks and benefits in each individual case must be considered. A consultant anaesthetist with expertise in the management of high-risk pregnancy should be involved in the decision making.
Management of intrapartum anticoagulation should be discussed with both the haema- tologist and the cardiologist. Recent guidelines have not recommended routine prophylactic antibiotic cover for labour but many centres continue to give this, and it is recommended that this should be discussed with the patient. All drug therapy should be discussed with a cardiologist with expertise in the management of CHD.
Key points
• Cyanotic congenital heart disease is associated with high maternal and fetal morbidity and mortality.
• Multidisciplinary antenatal and intrapartum care is essential, and an individualised plan for delivery should be made.
• Regional analgesia for labour is usually beneficial; choice of anaesthetic technique for caesarean section is controversial.
Further reading
Connolly HM. Managing congenital heart disease in the obstetric patient. Semin Perinatal 2018; 42: 39-48.
European Society of Cardiology. ESC guidelines on the management of cardiovascular diseases during pregnancy: the Task Force on the Management of Cardiovascular Diseases during Pregnancy of the European Society of Cardiology (ESC). Eur Heart J 2011; 32: 3147-97.
Stout K. Pregnancy in women with congenital heart disease: the importance of evaluation and counselling. Heart 2005; 91: 713-14.
Swan L. Congenital heart disease in pregnancy. Best Pract Res Clin Obstet Gynaecol 2014; 28: 495-506.