FRCA Notes

Cardiac Disease in Pregnancy

This topic featured as a CRQ in March 2021 (60% pass rate) - marks were lost on applied basic sciences.

This page is an overview of cardiac disease in pregnancy, with separate dedicated pages on arrhythmia, pulmonary hypertension and peripartum cardiomyopathy.

Resources

  • Cardiac disease is the most common indirect cause of maternal death in the UK (CMACE 2006-08)
  • The incidence of maternal death due to cardiac disease is rising, mainly due to an increasing incidence of acquired cardiac disease
  • The overall incidence of cardiac disease during pregnancy is 1%
  • The majority of this is congenital heart disease, accounting for 75-85% of cardiac disease during pregnancy
  • Those with congenital heart diseases often undergo pre-conception counselling by cardiologists and obstetricians

Acquired cardiac disease

  • Conversely, many women with acquired cardiac disease are unaware of their condition
  • Risk factors for acquired cardiac disease are as standard, including advanced maternal age, diabetes, essential hypertension and obesity
  • The commonest acquired cardiac conditions leading to death are ischaemic heart disease and MI
  • In the developing world, rheumatic heart disease is also a significant problem

  • The outcome of pregnancy is often predicted by the functional status of a patient e.g. NYHA classification
Class Description
I No limitation of physical activity. Ordinary physical activity doesn't cause undue fatigue/palpitations/dyspnoea
II Slight limitation of physical activity. Comfortable at rest. Ordinary activity leads to fatigue/palpitations/dyspnoea
III Marked limitation of physical activity. Comfortable at rest but less-than-ordinary activity leads to fatigue/palpitations/dyspnoea
IV Unable to carry out any activity without discomfort. Symptoms at rest, which worsen during activity
  • Patients with NYHA class I or II symptoms generally tolerate pregnancy well
  • Certain conditions make women very high risk even in the absence of symptoms or functional limitation e.g. Marfan's syndrome with aortic root dilatation

Pre-assessment

  • Woman with known cardiac disease considering pregnancy should have pre-conception:
    • Assessment of disease severity and optimisation of treatment by a cardiologist
    • Optimisation of treatment by a cardiologist
    • Counselling by cardiologists and obstetricians regarding the risks of pregnancy/delivery (in women with WHO III or IV cardiac disease)
    • Information regarding the risk of inheritance e.g. congenital aortic stenosis, HoCM

Risk assessment

  • All women with cardiac disease should be risk-assessed according to the modified WHO risk classification (see below)
  • There should be multidisciplinary risk assessment from obstetricians, cardiologists and obstetric anaesthetists to plan ante-natal and peripartum care
  • Follow-up frequency depends on WHO class e.g. class I (1-2x in pregnancy), class II (1x per trimester) or class III/IV (1-2x per month)
WHO Class Condition
I Isolated atrial or ventricular ectopic beats
Uncomplicated or mild pulmonary stenosis, PDA or mitral valve prolapse
Successfully repaired simple lesions e.g. ASD, VSD, PDA
II Most arrhythmias (if well)
Un-operated ASD/VSD
Repaired ToF
II - III Mild LV impairment
HoCM
Marfan syndrome (without aortic root dilation)
Bicuspid aortic valve but aorta <45mm
Valve disease (native or tissue) not falling into other categories
Repaired coarctation
III Aortic root dilation (40-45mm in Marfan's, 45-50mm in bicuspid valve)
Mechanical valve
Complex congenital cardiac disease e.g. Fontan, unrepaired cyanotic dx, systemic RV
IV
Pregnancy 'contra-indicated'		 Pulmonary arterial hypertension (any cause)
Severe systemic LV dysfunction (NYHA III/IV, LVEF <30%)
Previous peripartum cardiomyopathy and residual LV dysfunction
Aortic root dilation >45mm (Marfan) or >50mm (bicuspid valve)
Severe MS, AS or coarctation

Investigations

  • Most pregnant women will have a normal ECG
  • Changes in the position of the heart, due to the gravid uterus, may cause physiological ECG changes:
    • LVH
    • 15-20' left axis deviation
    • ST-segment and T-wave changes
    • Lead III: Q-wave and inverted T-wave
    • Lead AvF: attenuated Q wave
    • V1-3: inverted T-wave
    • Atrial or ventricular ectopics
    • Sinus tachycardia

Cardiac catheterisation

  • May be required to diagnose or treat coronary artery disease
  • The safest time to perform angiography is in the second trimester (13th - 28th week), because:
    • Organogenesis is complete
    • The foetal thyroid is inactive
    • The small foetus can be readily shielded from radiation

Surgery

  • Maternal morbidity from cardiac surgery and cardiopulmonary bypass is similar to that of non-pregnancy women
  • There is, however, a high foetal morbidity and mortality

  • Surgery should ideally be in the second trimester (13th - 28th week) to optimise foetal outcome
  • For surgery required after 28 weeks, delivery by LSCS usually precedes cardiac surgery

Goals

  • Minimise cardiovascular stress by minimising the work of labour and delivery
  • Monitor and maintain fluid balance
  • Avoid aortocaval compression
  • Provide aspiration prophylaxis
  • Implement invasive monitoring

Assisted vaginal delivery ± early, incremental, epidural analgesia

  • This mode of delivery is advantageous over un-assisted vaginal delivery because there are fewer surges in cardiac output associated with pushing
  • It is also advantageous over LSCS due to:
    • Less blood loss
    • Reduced stress response
    • Reduced incidence of post-partum pulmonary complications, sepsis and VTE

  • Early, incremental, epidural analgesia has several advantages:
    • Limits increased cardiac output from pain due to analgesic effect
    • Reduces both preload and afterload
    • Limits sympathetic block by careful titration of the level of epidural block required
    • May be topped up for anaesthesia if required

Caesarean section

  • Typically reserved for either obstetric indications or specific, high-risk maternal conditions:
    • Marfan syndrome with aortic root dilation >45mm
    • Acute or chronic aortic dissection
    • Intractable cardiac failure
    • Severe pulmonary artery hypertension
    • Severe aortic stenosis
  • The choice of anaesthetic for a LSCS should take into account the underlying cardiac disease and severity, wishes of the mother and anaesthetist's preferences

Uterotonics

  • Oxytocin when given as a rapid bolus can cause marked tachycardia, reduced SVR and reduced PVR
    • Therefore boluses are avoided and an infusion alone may be used
  • Ergometrine is avoided as it causes increased SVR, PVR and coronary vascular resistance
  • Carboprost should be avoided due to profound vasodilation, especially when SVR maintenance is important e.g. aortic stenosis

  • Planned obstetric interventions, e.g. B-lynch sutures, Bakri balloons, should be used to treat MOH instead

  • Chosen technique should aim to be cardiovascularly stable/titratable, reliable (good block) and familiar to the anaesthetist
  • Therefore the technique of choice is typically:
    • Incremental epidural
    • Combined CSE with low-dose (<1ml) spinal then incremental epidural boluses
    • Continuous spinal anaesthetic technique (although unfamiliar to most and associated with high rates of PDPH)

  • Vasodilation is a feature and should be controlled with titratable vasopressors
    • Phenylephrine is preferred in stenotic valve lesions to maintain SVR
    • Ephedrine is preferred in regurgitant valvular lesions due to its positive chronotropic effect


Advantages Disadvantages
Reduced maternal anxiety: ↓ catecholamine release and less cardiac work Those inherent to GA, inc. aspiration, failed I&V, anaesthetic effects on foetus
Stable parameters if 'cardiac anaesthetic' provided ↑ blood loss compared to regional anaesthesia
Suitable in the anticoagulated patient Cardiac instability due to pressor effects of intubation
Effect of GA drugs, which are typically cardiac depressants and/or vasodilatory

Monitoring

  • Standard AAGBI monitoring
  • Arterial line
  • Central line may be required, although caution is required with CVP monitoring in the obstetric patient as:
    • Anatomical variation of the SVC may mean CVC line tip is not where it should be
    • Irritation by the CVC line may precipitate arrhythmias
    • Underlying cardiac disease means CVP may not reflect LVEDV
    • CVP may be a less reliable guide to volume status, especially in PET
  • TOE may be useful

Conduct

  • One should aim to avoid tachycardia and large swings in blood pressure
  • At induction, obtund the hypertensive response to intubation (e.g. alfentanil 25μg/kg, remifentanil 0.5μg/kg) and titrate induction agent carefully
  • Maintenance is typically with volatile anaesthetic, although addition of remifentanil is useful to:
    • Reduce volatile requirement and therefore risk of atonic PPH
    • Reduce chance of hypertension on extubation if continued during emergency

  • Good analgesia is paramount because pain and tachycardia increase cardiac work; epidural/neuraxial opioids and use of other regional techniques e.g. TAP blocks

  • Planned admission to HDU/ITU may be required for 24-48hrs post-delivery
  • Mortality due to maternal cardiac disease tends to be post-partum, due to:
    • Reduced frequency of monitoring compared to ante-natal period
    • Large fluid shifts in the post-partum period including 500ml autotransfusion at the time of delivery → acute decompensation
    • Sub-optimal or early withdrawal of analgesia leading to catecholamine surges from pain → worsening cardiac function or arrhythmias