Syncope toolkit: Pregnancy and syncope

Pregnancy and syncope

Syncope occurs in up to 4.6% of pregnancies. Most women with vasovagal syncope (VVS), orthostatic hypotension (OH) and postural tachycardia syndrome (PoTS) will have a safe delivery and a healthy baby. However, syncope may be associated with slightly higher rates of adverse outcomes including preterm births and congenital anomalies, and an increased incidence of maternal cardiac arrhythmias and syncope in the first-year postpartum.

In this section:

Causes of syncope in pregnancy

Causes of syncope and low blood pressure in pregnancy include:

Vasovagal syncope
Pulmonary embolism
Haemorrhage eg ruptured ectopic pregnancy, aortic dissection
Uterine rupture
Amniotic fluid embolism
Cardiac causes include peripartum cardiomyopathy, coronary or aortic dissection, SVT, VT
Supine hypotensive syndrome (aorto-caval compression)
Orthostatic hypotension
In relation to PoTS.

Non syncopal causes of blackouts in pregnancy:

Hypoglycaemia
Eclamptic seizures.

Risks of VVS, OH and PoTS in pregnancy

Vasovagal Syncope - occasional report of abruption, fetal hypoxia.

Low blood pressure – some small studies suggest a slight reduction in birth weight and increase in stillbirth. Mechanism and management is unclear.

PoTS – pregnancy is safe in PoTS for mum and baby. No increase in miscarriage, preterm delivery, stillbirth or perinatal mortality.

Paternal syncope is not uncommon and is also a risk! Trauma to both mother and father can occur.

Supine hypotensive syndrome

Points to consider:

This occurs due to aorto-caval compression
Within 3-7 minutes, around 30% of the effective circulating blood volume can be effectively lost and significant hypotension occurs
Can occur from 19 weeks of pregnancy – when supine
Effect on mum: hypotension associated with dizziness, pallor, sweating, nausea, syncope or near syncope, tachycardia (bradycardia in late stages), lower limb oedema
Effect on baby: fetal hypoxia or death
Management – turn onto left side when supine or sit upright.

Palpitation and Arrhythmias in pregnancy

The majority of arrhythmias in pregnancy are not harmful. However physiological changes in pregnancy may trigger arrhythmias, some of which can lead to syncope.

Benign palpitations – it is normal for heart rate to increase by 25% in pregnancy, and ectopic beats occur in around 50%, and both therefore cause palpitations.

Structural heart disease - this may present for the first time in pregnancy, for example mitral stenosis. In women with known structural heart disease (such as congenital heart disease, acquired valvular disease, cardiomyopathy), arrhythmia is a predictor of a cardiac event during the pregnancy and should therefore be treated as a red flag. Women with structural heart disease may require referral to a tertiary obstetric centre to plan a safe pregnancy and delivery.

Electrical heart disease – such as accessory pathways or Wolff-Parkinson-White, AV-nodal re-entrant tachycardia, channelopathies, drug-related long QT.

Planning a pregnancy with syncope

When planning a pregnancy with syncope, you should:

Provide the usual preconception advice
Maximize wellness before pregnancy – self-care measures
Stop any drugs that are contraindicated - see UKTIS website
Counsel the patient regarding the risk and benefit of continuing drugs and seek secondary care consultant advice where appropriate
Consider any associated conditions which may impact the pregnancy such as cardiac disease, hypermobile Ehlers-Danlos syndrome, chronic fatigue syndrome and autoimmune conditions
Refer to specialist maternity services if syncope is due to a cardiac cause for preconception advice - find out more about cardiac disease and pregnancy from the Royal College of Obstetricians and Gynaecologists.

Safety in pregnancy of medication used in VVS, OH and PoTS

Drug	Use in pregnancy	Effects	Safety in pregnancy and breast feeding
Fludrocortisone	Addison’s	Monitor sodium, potassium and magnesium	Safe
Ivabradine		Harmful in animals	Not safe
Midodrine	Limited experience	Gastroschisis (theoretical risk) No human data	Not recommended - no data
B Blockers: Labetalol	1st line in hypertension	Slight intrauterine growth retardation	Safe
B Blockers: Propranolol	Various uses	Slight intrauterine growth retardation	Small dose safe
B Blockers: Bisoprolol	Newer drug	Slight intrauterine growth retardation	Unclear
Pyridostigmine	Myasthenia Gravis		Safe
Clonidine	Pre-eclampsia	Like methyl dopa	Probably safe
Octreotide	Limited data		Caution

Table adapted from consensus document 2007.

Self-care measures for VVS, OH and PoTS in pregnancy

Self-care measures include:

High fluid intake (unless contraindicated)
Increase salt (unless contraindicated)
Compression tights or stockings
Some women will improve as pregnancy progresses; this is thought to be related to the 50% increase in plasma volume in late pregnancy.

Labour and delivery

In general the management of the delivery follows normal obstetric guidelines and is not altered by the fact that the patient experiences syncope.

Note that:

Upright posture and warm baths should be avoided
Squatting may relieve symptoms, but standing up after squatting may exacerbate them.

Anaesthetic considerations

Anaesthetic considerations include:

Hypotensive tendency or intraoperative hypotension
Epidurals and spinals can be used but can worsen hypotension
Early use of intravenous infusion, especially if fasting.

Postnatal period

Things to consider in the postnatal period:

Early mobilisation after delivery
Extra fluids when breast feeding
Consider compression tights
Pacing of activities.

In PoTS, most women report improvement 6-12 months after pregnancy

Syncope investigations in pregnancy

Considerations for syncope investigations in pregnancy:

Mostly investigations can wait unless cardiac syncope is suspected
Echo, exercise ECG and some pharmacological challenges may be undertaken
Active stand test can be undertaken in pregnancy
Tilt test is contraindicated in pregnancy
Symptom diary and heart rate or blood pressure recordings can be helpful.

Devices in pregnancy

Considerations for devices in pregnancy:

Insertable Cardiac Monitors (ICMs) are not contraindicated in pregnancy
DC cardioversion can be safely administered where necessary throughout pregnancy
pacemakers – should be avoided if possible under 40 years old - however, insertion of a pacemaker during pregnancy does not appear to cause maternal or fetal complications
women with implantable cardioverter defibrillators (ICDs) have achieved successful pregnancies, even when the devices have been triggered.