Background

Hypotension following neuraxial anaesthesia is common and typically managed with phenylephrine. In patients with severely reduced left ventricular ejection fraction (LVEF), pure α-agonists may:
• Increase afterload

• Reduce cardiac output
• Trigger reflex bradycardia
• Worsen haemodynamic instability
Noradrenaline provides α-vasoconstriction with modest β1 inotropy, potentially offering a more favourable profile in cardiac disease. (Fig 1)

Dr I E Roberts, Dr D Leslie, University Hospital of Wales

Vasopressor Response

Following neuraxial block, the patient developed significant hypotension. Phenylephrine (first-line)
• Initiated as per standard obstetric practice
• Failed to maintain MAP ≥65 mmHg

• Concern for reduced cardiac output due to reflex bradycardia and increased afterload

Switch to Noradrenaline (16mcg/ml) (Alpha v Beta) • MAP stabilised between 65–80 mmHg
• HR maintained at 90–100 bpm
• Oxygen saturation remained ≥99%

• Marked improvement in haemodynamic stability
Estimated blood loss: 933 mL Delivery was uncomplicated; neonate well.

Postoperative Course

• Epidural retained for 24 hours for analgesia (Morphine allergy) • Continued diuresis and cardiac optimisation
• Persistent LV dysfunction postpartum (EF 34–35%)
• No further hypotensive episodes

• Ongoing heart failure therapy and cardiology follow-up

Discussion

Haemodynamic physiology & vasopressor choice

• Neuraxial anaesthesia → ↓SVR and preload

• Healthy parturients maintain CO via ↑HR and stroke volume

• In severe LV dysfunction, compensation is limited → vasopressor

choice critical

Why phenylephrine underperforms

• Pure α1-agonist → ↑afterload

• Dilated LV → ↓stroke volume

• Reflex bradycardia → ↓CO (Fig 2 and 3)

• May worsen perfusion

• Observed in this case: inadequate

  MAP despite escalation

  Why noradrenaline is preferable

  • α1 vasoconstriction restores MAP
  • β1 effect supports contractility and HR
  • Better CO preservation
  • Less reflex bradycardia
  • Evidence: ↑CO, more stable HR, similar

  foetal outcomes (Fig 2 and 3)

  Clinical implications

  • Individualise vasopressor choice in cardiac disease

  • Avoid phenylephrine in severe LV dysfunction

  • Noradrenaline provides balanced haemodynamics

Fig 2. Vasopressor response in Normal heart

Anaesthetic Technique

A combined spinal–epidural (CSE):
• Spinal: 1 mL 0.5% hyperbaric bupivacaine + fentanyl + morphine • Epidural: Incremental levobupivacaine
• Arterial line inserted pre-operatively
• Difficult spinal (3 attempts)
Caesarean delivery proceeded under CSE.