On successfully completing this topic, you will be able to:
understand the serious cardiac, diabetic and neurological problems that can affect pregnant women
anticipate the health problems of women with pre-existing disease
appreciate the critical diagnostic features heralding emergencies in pre-existing and new conditions
take part in the urgent multidisciplinary care of pregnant and puerperal women with complex disorders
understand important aspects of service provision for such women with complex disorders.
Introduction and incidence
The recent confidential enquiries report approximately 50 deaths due to cardiac disease each trienna, and cardiac disease remains the most common cause of maternal death. Substandard care has been highlighted in approximately half the deaths although details of the recent deaths since 2009 are to be reported late 2015.
There were five deaths from diabetes in the 2009–2012 confidential enquiry: two were probable hypoglycaemia while three others were from diabetic ketoacidosis. While diabetes remains an uncommon cause of indirect maternal death the rising incidence of this condition will increase the volume of emergency complications which must be recognised and managed promptly.
Considering the neurological deaths there were 26 deaths from stroke and 14 deaths from epilepsy reported in the 2009–2012 MBRRACE report. Stroke care should be the same irrespective of pregnancy, while epilepsy care should focus on pre-conceptual counselling and multidisciplinary case. Deaths from epilepsy are more common than deaths from pre-eclampsia, and the risk of SUDEP (sudden unexplained death in epilepsy) is increased by pregnancy. Especially so are the recommendations to take due note of pre-existing disease and to work within a multidisciplinary, specialist team, both to avoid and to treat emergencies in complex cases.
Cardiac disease
Cardiac disease can be divided into congenital heart disease and acquired heart disease, with maternal deaths from acquired heart disease greatly exceeding those from congenital heart disease. However, since more women with congenital heart disease are now surviving into their childbearing years, the number of women with congenital heart disease seen in antenatal clinics is increasing with a prevalence estimated to be around 0.8% in the antenatal population.
The main cardiac causes of maternal death are sudden adult death syndrome (SADS), peripartum cardiomyopathy, aortic dissection, myocardial infarction and myocardial ischaemia.
Acquired heart disease
SADS
The case definition for SADS is a sudden unexpected cardiac death (i.e. presumed fatal arrhythmia) where all other causes of sudden collapse are excluded, including a drug screen for stimulant drugs such as cocaine. Ten women died of SADS in the 2006–08 triennium, more than in any previous triennium. Six of the women were obese. Obesity appears to be associated with cardiac hypertrophy, and both obesity and cardiac hypertrophy are risk factors for arrhythmia.
Cardiomyopathy
There are different types of cardiomyopathy – peripartum, dilated and hypertrophic.
Peripartum cardiomyopathy typically presents either as a woman approaches term or in the first few weeks after delivery, although it can occur up to five months postpartum. While it is commoner in older, obese, black or hypertensive women, it can present in women with no risk factors who have previously been well. Unexplained breathlessness, tachycardia, gross oedema or supraventricular tachycardia should prompt a chest radiograph, ECG and echocardiography. Prior to delivery, peripartum cardiomyopathy can be treated with diuretics and beta-blockers, with angiotensin-converting enzyme (ACE) inhibitors being added after delivery or in very severe cases. There is a high recurrence risk in future pregnancies and women with cardiomyopathy should receive preconceptual counselling prior to embarking on further pregnancies.
If dilated cardiomyopathy is considered, anticoagulation should be instigated to prevent intracardiac thrombus formation.
Hypertrophic obstructive cardiomyopathy (HOCM) is an autosomal dominant condition which shows anticipation (gets worse in each subsequent generation). Usually pregnancy outcome is good unless there is severe diastolic dysfunction. Output may be compromised by:
Acute myocardial infarction (MI) and ischaemic heart disease
Mortality from acute coronary syndromes has been estimated at 11% and is highest in peripartum women. The majority of women who die from acute MI or ischaemic heart disease have identifiable risk factors relating to lifestyle, such as increased maternal age (odds ratio (OR) = 6.7 for age >30 years), diabetes, obesity or smoking. Other risk factors include hypertensive disorders and existing thrombophilias. Infection in the third trimester and postpartum seems to heighten the risks further.
Pathophysiology
The predominant mechanism for MI in the nonpregnant population is rupture of an atheromatous plaque causing coronary occlusion. In pregnancy, 50% of MIs are thought to be caused by coronary artery dissection resulting in coronary artery occlusion. This is rare in the nonpregnant population. Coronary thrombosis may occur without underlying atherosclerosis, due to the hypercoagulable state that naturally exists in pregnancy.
The demands on the cardiovascular system increase with the rising oxygen demands of the developing fetus and uterus. Labour adds a further cardiovascular challenge, with increasing catecholamine stimulus due to pain. The highest incidence of coronary dissection occurs immediately after delivery.
Presentation
Chest pain should always be taken extremely seriously in pregnancy, as should other symptoms of cardiac disease, such as fatigue, dyspnoea, palpitations and syncope.
Diagnosis
Failure to consider the diagnosis of ischaemic heart disease in women presenting with chest pain during pregnancy is a common failing. There should be a high index of suspicion, particularly if the woman requires opiate analgesia for the chest pain, and there should be a low threshold for further investigation.
ECG
The diagnostic ECG criteria are the same as in the nonpregnant state with elevated ST segments and Q waves. Cardiac enzymes will also be raised. However some difficulties may be encountered in the interpretation of ECG results. ST elevation may be a normal finding in the third trimester, along with left axis deviation. Q waves may be seen along with mildly inverted T waves in lead III in normal pregnancy (ST segment depression is also commonly seen in women undergoing anaesthesia for CS).
Blood tests
In general, troponin is the preferred biochemical diagnostic marker for cardiac disease in pregnancy, although it can be elevated in pre-eclampsia or gestational hypertension; it is not affected by labour or surgery. Additionally, serum creatine kinase-MB may be raised in association with uterine contractions.
Imaging
A coronary angiogram can be performed with effective abdominal shielding to reduce fetal irradiation (see Chapter 4: Appendix ‘Radiology in the pregnant woman’). Echocardiography is usually not used as a definitive test, but may be used in pregnancy due to its noninvasive nature, at least to look at ventricular function and wall motion abnormalities. It is also useful in excluding valvular problems or aortic dissection.
Treatment
Modern treatment of acute MI requires prompt diagnosis, oxygen via facemask if SaO2 readings are below 95%, pain relief e.g. intravenous diamorphine, and urgent referral to a cardiac team with the intention of achieving rapid reperfusion. This may be achieved either by the provision of thrombolytic drugs, or by primary percutaneous coronary intervention (PCI), often with the provision of a coronary stent. The current thinking is to prefer PCI.
Difficulties in planning treatment in pregnancy include the hazards of the fetus requiring urgent delivery and also the risks of haemorrhage in the peripartum period.
PCI may have some radiation risk to the fetus but also requires prolonged antiplatelet therapy. Drug requirements are relatively much greater when drug-eluting stents are used as opposed to bare metal stents. Consideration of whether to stop these drugs or not has to be addressed in the context of CS and regional anaesthesia. Bare metal stents would be the treatment of choice in pregnancy.
Thrombolytic therapy has been traditionally thought of as contraindicated in pregnant women although, of course, they were naturally excluded from all clinical trials. There has been some clinical experience suggesting that haemorrhage remains a real threat, particularly in the peripartum and postpartum period. However, during pregnancy it is thought that there is little transplacental passage of streptokinase and other similar agents, so these may not pose a risk to the fetus. In association with a coronary dissection, the use of thrombolytic therapy could worsen the bleeding. As this is a common cause of acute MI in pregnancy, it is likely that PCI, where available, will be preferred over thrombolytic therapy.
Coronary artery or other cardiac surgery is only performed when there are complications such as coronary dissections or catastrophic valvular dysfunction. If still pregnant, it is recommended that fetal heart monitoring should be conducted to ensure adequate bypass pump flow. Depending on the stage of pregnancy, a choice may be made to deliver the fetus at the time of coronary surgery.
Drug therapy after MI
In the nonpregnant population, follow-up therapy would include a wide variety of drugs, many of which are aimed at vasodilatation or suppression of platelet activity (see Table 22.1). Planning therapy in a pregnant woman has to take account of the varied side effects on the fetus and passage into breast milk for the lactating mother.
Choice of delivery
Where possible, the delivery should be delayed to allow time for healing of the myocardium. This will not always be possible. There appears to be no evidence that either method of delivery is better than the other and each has its risks. Care to reduce cardiac work, in the form of adequate pain relief and minimal pushing, will be needed as for other women with cardiac disorders. Great care should be taken with syntocinon due to the vasodilatation, and ergometrine is contraindicated due to the possible spike in blood pressure it might provoke.
Aortic dissection
Of the disorders affecting the aorta during pregnancy, Marfan’s syndrome and Ehlers–Danlos Type IV are the most important. Women with bicuspid aortic valves are also at increased risk of aortic dissection. Approximately 80% of women with Marfan’s have some cardiac involvement, the majority having mitral valve prolapse. Patients with Marfan’s should have regular echocardiograms during pregnancy to look for an increase in the aortic root diameter.
Risk of aortic dissection:
aortic root diameter less than 4 cm 1%
aortic root diameter more than 4 cm 10%.
The time of greatest risk is in labour and immediately postpartum when cardiac output is increased. Hypertension increases the risk of dissection and the systolic blood pressure should be carefully monitored and controlled. Women with Ehlers–Danlos Type IV are known to be at risk of aortic dissection even if the aortic root is of normal size.
Consider the diagnosis in women with:
central chest, jaw or interscapular pain – i.e. remember not all chest pain is due to pulmonary embolism
family history (Marfan’s and Ehlers–Danlos IV are usually autosomal dominant)
women with a known bicuspid aortic valve.
Valve disease
Regurgitant valve disease
Although cardiac output increases in pregnancy, the reduction in systemic vascular resistance compensates in part for this, and pregnancy is generally well tolerated.
Prosthetic valves
Women with mechanical prostheses require anticoagulation throughout pregnancy. There is debate as to which anticoagulant regimen to use. LMWH does not cross the placenta and is therefore safer for the fetus, but may be associated with a higher risk of valve thrombosis, particularly if patient noncompliance is a concern. Whatever the anticoagulation regime, pregnancy in a patient with a mechanical prosthesis is associated with a maternal mortality between 1 and 4%, mainly due to valve thrombosis.
Congenital heart disease
Congenital heart disease accounts for <10% of all maternal deaths due to cardiac causes. However, more women with congenital heart disease are now surviving until their child-bearing years and are the group of women most commonly seen antenatally in a joint obstetric cardiac clinic. Since this group of women are known to the healthcare services prior to pregnancy, there is an opportunity to offer preconceptual counselling. Pre-pregnancy counselling should include a frank discussion of the risks to enable a woman to make an informed choice about whether to embark on pregnancy or not.
At the time of booking for antenatal care, it is important to define the lesion and determine what surgery has been done previously. Women with surgically corrected congenital heart disease are still at risk, as there may be a residual defect. A specific recommendation from the most recent maternal mortality report is that, ‘Women with a known history of cardiac disease must be referred for consultant-led obstetric care in a maternity unit where there is a joint obstetric/cardiology clinic or a cardiologist with expertise in the care of women with heart disease in pregnancy.’
Service provision for women with heart disease
Preconceptual care
If women are known to have heart disease prior to pregnancy, pre-pregnancy counselling should be offered and is ideally performed jointly by an obstetrician and a cardiologist including:
a frank discussion of the risks involved to enable the woman to make an informed choice as to whether to embark on pregnancy or not
optimising cardiac function (medically, e.g. control arrhythmias, or surgically, e.g. valvotomy)
review and adjust medication, avoiding teratogens
contraception advice if the woman decides against embarking on pregnancy
contact numbers to facilitate early referral once pregnant.
Women undergoing assisted conception often have additional risk factors such as increased age, the risk of ovarian hyperstimulation and multiple pregnancy.
Early pregnancy
Ideally, women with heart disease should be referred to a joint obstetric cardiac clinic. There should be:
easy access to facilitate prompt referral
accurate information gathered about the type and severity of the cardiac disease, previous and current treatments
a frank discussion of the risks involved to enable the woman to make an informed choice whether to continue with the pregnancy or not
professional interpreter (if needed) to ensure that relevant history is disclosed. Interpreters from within the family should not be used as, in the family’s desire to help the woman have a successful pregnancy, risks may not be accurately relayed to the patient
for women who choose not to continue the pregnancy, there should be easy access to termination of pregnancy in a hospital that can care for a woman with heart disease. Infection, bleeding and the need for an anaesthetic are recognised complications of termination and will pose a more significant risk to a woman with cardiac disease.
Awareness of cardiac disease in the antenatal population
Recognition of relevant history, important signs and symptoms which may prompt referral to a cardiologist:
unexplained breathlessness
isolated systolic hypertension
interscapular pain
severe chest pain not due to thromboembolism
polycythaemia
tachycardia.
Guidelines are needed locally to enable:
recognition of risk factors at the time of the initial antenatal visit and facilitate appropriate referral
the appropriate pattern of care to be initiated that would ideally be hospital-based care with a joint cardiac obstetric clinic for high-risk women
follow up of women with heart disease who do not attend for care
multidisciplinary management of women with heart disease to plan delivery or to facilitate prompt attention if their condition deteriorates.
Appropriate response to cardiac arrest is needed:
knowing how to call the arrest team for an obstetric patient
efficient bleep system to ensure that the appropriate people, including an obstetrician and a paediatrician, are called
resuscitation training and drills specifically directed at cardiac arrest in a pregnant woman, for example, Advanced Life Support in Obstetrics (ALSO) and MOET courses
well-maintained equipment with which staff are familiar.
Inherited cardiac disease:
family members may also be at risk of cardiac disease and may need to be screened, for example, for Marfan’s disease, HOCM and possibly SADS
fetal echocardiography may be indicated if either parent had congenital heart disease
The 22q11 deletion in either parent would increase the risk of congenital heart disease in the fetus.
Multidisciplinary care plan
This should include a plan for management during pregnancy, intrapartum and postpartum. It should include contingency planning for such conditions as preterm labour and postpartum haemorrhage; and contact numbers for members of the multidisciplinary team.
Delivery
Generally aim for a vaginal delivery, unless a woman cannot raise her cardiac output sufficiently for labour safely. Women where CS for cardiac indications may be appropriate include those with severely stenotic valves, poor ventricular function, ischaemia, cyanosis, some women with pulmonary hypertension and women with a dilated aortic root. During labour avoid hypotension, provide good analgesia and ensure careful fluid balance. Syntocinon given by an infusion over 10–20 minutes may be preferable to a bolus of syntocinon for management of third stage, and this should be specified in the individualised care plan. Ergometrine should also be used with great care and may be contraindicated in some obstetric conditions.
Postpartum
The majority of maternal deaths from cardiac causes occur postpartum. This is a time when increased vigilance is required, but when complacency often occurs. Maternal observations must be monitored regularly, by strict attention to and recording of fluid balance, with an appropriate response if abnormal.
Contraception
Appropriate contraceptive advice must be provided after any pregnancy. This allows time for reassessment of cardiac function and treatment to improve function, for example valvotomy. One successful pregnancy must not engender complacency. Some conditions, such as peripartum cardiomyopathy, have a high recurrence risk and assessment and discussion should occur prior to embarking on a further pregnancy. Other conditions worsen with age and in each subsequent pregnancy the risks would be higher.
Diabetes in pregnancy
Diabetes complicates 2–5% of pregnancies. It has been predicted that there will be a 35% increase in 30 years. Diabetes may affect women prior to pregnancy, or develop during pregnancy.
Aspects of diabetes that are affected by pregnancy include:
diabetic ketoacidosis (see Algorithm 22.1)
retinopathy – 50% risk of progression in pregnancy
nephropathy – 6% of women with pre-existing diabetes have nephropathy prior to conception. If moderate/severe renal impairment is present in early pregnancy, there is significant risk of deterioration.
hypertension – pre-existing hypertension is common; 12–40% develop pre-eclampsia
infection – more common in women with diabetes; in patients with type 1 diabetes who are pregnant, 80% will experience at least one infection, plus there is associated increased risk of preterm labour and ketoacidoisis
other associated endocrine problems, e.g. thyroid dysfunction.
Recent classification of diabetes in pregnancy is into five types:
type I diabetes mellitus (0.2–0.5% of pregnancies) inadequate insulin production
type II diabetes mellitus (0.2–2% of pregnancies) insulin resistance
impaired glucose homeostasis
gestational diabetes (1–6% of pregnancies, with 20–50% subsequently developing type
II diabetes)
diabetes due to specific aetiologies, including genetic, endocrine (Cushing’s), drug and infection induced.
Pregnancy is a state of physiological insulin resistance and glucose handling is significantly altered, especially in late pregnancy. Insulin requirement is likely to increase by 50% or more. Many complications are associated with maternal diabetes. Most of these are caused directly by persistent maternal hyperglycaemia. These complications include:
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