Pulmonary hypertension in the general population featured as an SAQ in September 2017, asking for definition, causes, specific anaesthetic goals and pharmacological treatments.
Pulmonary hypertension is a high-risk, high-mortality disease state
Pulmonary hypertension of any cause is a mWHO 2.0 class IV condition, carrying extremely high risk of maternal mortality or severe morbidity
The 2025 ESC guidelines no longer simply state that pregnancy is 'contraindicated'; instead women should receive expert counselling from the Pregnancy Heart Team with shared decision-making, including about termination
The risk of complications varies between individuals and is generally higher with greater pulmonary artery pressures, but there is no safe cut-off value for pulmonary artery pressure in pregnancy
It carries one of the highest risks of obstetric and foetal complications of any cardiovascular disease
Mortality tends to be from right heart failure owing to an inability to cope with the physiological changes of pregnancy
Mortality in parturients with pulmonary hypertension is decreasing with better therapies and MDT management, but still may be as high as 33%
Pulmonary hypertension
A blend of processes contribute to increasing PVR:
Sustained pulmonary vasoconstriction
Cellular proliferation in the vessel walls
Localised thrombi formation
Said vascular remodelling exhausts endogenous vasodilators (nitric oxide, prostacyclins) and up-regulates vasoconstrictors (endothelin 1)
There is consequent increases in RV afterload, abnormal ventricular remodelling and eventually RV dysfunction/failure, which is the primary determinant of survival in PAH
Pregnancy and PAH
Normally, the increased progesterone levels of pregnancy lead to pulmonary vasodilation & recruitment of non-perfused arterioles
However, in pulmonary hypertension the thickened and vasoconstricted pulmonary arteries are unable to accommodate the increased cardiac output & plasma volume of pregnancy
This leads to increased PVR, further RV strain and higher risk of RV ischaemia/failure
There may be consequential LV failure due to septal bowing and interventricular interdependence
The most hazardous period ante-partum is 20-30 weeks' gestation i.e. peak cardiac output
Further risk arises during labour, with raised PVR and altered RV preload due to:
Sympathetic stimulation from pain
Fluid shifts including autotransfusion from the placenta at delivery
Raised intrathoracic pressure from Valsalva
Risks persist up to 6 months post-partum, including the risk of VTE adding to pulmonary arterial microthrombus load
Maternal mortality is concentrated in the third trimester and the first 6 weeks post-partum as the periods of highest mortality
Most patients will have an ante-natal diagnosis, but patients may present in pregnancy with features of right heart failure
Symptoms
Exertional dyspnoea
Fatigue
Syncope
Chest pain
Dry cough
Peripheral oedema
Signs
Tachycardia
Raised JVP
Hepatomegaly
Ascites
Mottled and/or cool peripheries
Hypoxia
Murmurs (if valvular pathology)
Investigations
ECG
P-pulmonale
RV strain or hypertrophy
RAD
RBBB
Prolongation of the QRS and/or QTc in severe disease
TTE is the first line
Right heart catheterisation remains the gold standard for diagnosis
BNP/NT-proBNP should be measured before pregnancy and monitored during it
New diagnosis in pregnancy
Breathlessness and fatigue are easily attributed to normal pregnancy, so diagnosis may be delayed
Echocardiographic PA pressure estimates can be overestimated in pregnancy; confirm with right heart catheterisation where it will change management
Refer urgently to a PH centre and Pregnancy Heart Team
Pre-conception counselling and contraception
Women of childbearing potential with PAH wishing to become pregnant should be counselled by a multidisciplinary team about the very high risk, encouraging shared decision-making
Effective contraception should be discussed from an early age:
Levonorgestrel IUD or progestogen implant are the safest and most effective options
IUD insertion can provoke a vasovagal response, which is poorly tolerated; it should be performed with monitoring and an anaesthetist available
Oestrogen-containing contraception is avoided owing to VTE risk
Bosentan reduces the efficacy of hormonal contraception
If pregnancy occurs
The Pregnancy Heart Team should hold a clear discussion of the very high maternal and foetal risk, with a shared decision-making process regarding termination and psychological support
Termination, if chosen, should be performed without delay (risk increases with gestation) in an expert centre
MDT management in a specialist centre e.g. maternal–fetal medicine (MFM) obstetricians, cardiologists, obstetric anaesthetists and midwives
May need input from ICM (± ECMO), haematology, cardiothoracics and neonatologists too
Regular reviews (1-2x/month) and prompt investigation of deterioration in functional capacity, as this is the best prognostic indicator
Therapies
Targeted therapy should be continued or started, as untreated PAH carries the greater risk
PDE-V inhibitors are first-line therapy e.g. sildenafil
Calcium channel blockers can be continued in the small group of vasoreactive responders
Prostacyclin analogues are also suitable in pregnancy
They may increase bleeding risk and cause thrombocytopaenia, although there aren't reports of neuraxial haematoma
Endothelin receptor antagonists (e.g. bosentan, ambrisentan, macitentan) are teratogenic and contraindicated; they should be stopped and substituted
Riociguat (a soluble guanylate cyclase stimulator) is contraindicated
Anticoagulation will need to be managed; those on warfarin or DOACs require transition to LMWH (DOACs are not recommended in pregnancy)
Avoid fluid overload with reduced oral intake of water and salt, although diuretics may be used (furosemide; spironolactone is contra-indicated)
Correction of iron deficiency, which is common in those with pulmonary hypertension in pregnancy
Mode of delivery
A detailed delivery plan should be agreed in advance by the Pregnancy Heart Team and shared with the patient
Planned delivery is preferable to emergency delivery; timing balances maternal and neonatal risks, commonly around 34-36 weeks but individualised (earlier if deteriorating)
Delivery should be in an expert centre with ICU and, ideally, ECMO available
Mode of delivery is individualised; there is no robust evidence favouring either
Planned caesarean delivery has traditionally been favoured to avoid the physiological strain of labour, but this is by consensus only
Across cardiovascular disease, ESC 2025 notes planned caesarean delivery confers no maternal advantage over planned vaginal delivery
Vaginal delivery (with early epidural and an assisted second stage) benefits from reduced infection, haemorrhage and VTE risk, and may be suitable especially in the multiparous patient
Haemodynamic management
Goals include:
Avoid rises in PVR and RV afterload e.g. by avoiding hypoxia, hypercapnia, acidosis, pain or high airway pressures
Maintain SVR
This is achieved by:
Continuation of existing pulmonary vasodilator therapy e.g. PDE-5 inhibitors, prostacyclin
Careful fluid balance monitoring inc. concentrating drugs where possible
Supplementary oxygen
Positive inotropic support e.g. dobutamine, milrinone, adrenaline
Vasopressors to counteract vasodilation from neuraxial intervention e.g. noradrenaline, vasopressin (NB phenylephrine is contraindicated)
Analgesia and anaesthesia
Regional technique with a carefully titrated lumbar epidural is the recommended method of labour analgesia
Neither entonox nor opioid analgesia is recommended as they can precipitate hypoxia, hypercapnia and/or increase PVR
Either epidural top-up or CSE technique is preferable for operative delivery
The authors of the above-linked BJA article use 1ml 0.5% heavy marcaine (5mg) + fentanyl + morphine followed by incremental epidural top-up
A single-shot spinal is contraindicated owing to the propensity for rapid haemodynamic changes which can compromise RV function
GA may be required (e.g. anticoagulation contraindicates neuraxial technique, patient unable to lie flat)
It carries high risk and is reported to carry a 4x increased mortality vs. RA
Monitoring
Association of Anaesthetists standards
Continuous ECG and pulse oximetry
Arterial line
CVC (for vasoactive drugs)
PA catheter is of uncertain benefit, carries complications and should be avoided in most cases; minimally invasive cardiac output monitoring and TTE/TOE are preferable where possible
Uterotonics
Oxytocin boluses should be avoided, or only very small boluses (0.1 IU) used
Oxytocin should preferentially be diluted and infused slowly, e.g. 2IU over 10 minutes followed by 12mU/min for 4 hours in cardiovascular disease
Carboprost (↑ PVR) and ergometrine (↑ SVR and PVR) should both be avoided
Misoprostol is considered safe, but is less effective
Pulmonary hypertensive crisis
Most likely to present post-partum, but can occur at any time
Presents with features of acute right heart failure
Management involves:
Correction of underlying abnormal physiological factors which are contributing e.g. hypoxia, hypercapnia etc.
Pulmonary vasodilatory therapy e.g. inhaled nitric oxide, prostacyclins
Positive inotropy e.g. dobutamine, milrinone
Vasopressor to support RV perfusion
Reduced RV afterload e.g. diuretics
Highest risk period is post-partum; mortality is highest in the first month after delivery
Monitor in an HDU/ICU setting; prolonged monitoring is advised as decompensation commonly occurs in the days after delivery
Continue pulmonary vasodilator therapy; drugs stopped in pregnancy (e.g. ERAs) may be restarted, but are not compatible with breastfeeding
Ensure adequate thromboprophylaxis as at high risk of VTE
Careful fluid balance; diuresis may be required as the autotransfused volume is mobilised