Cardiac disease in pregnancy — structured oral station (12 minutes)

Opening prompt — "What is your working diagnosis and what is your immediate action?"

Model response, in this order: ^[1]

• "This is cardiac decompensation in a woman with a mechanical aortic valve at 36+5 weeks. She has pulmonary oedema and atrial fibrillation with a ventricular rate of 110 bpm."
• "I would call for help now: consultant obstetrician, consultant cardiologist, consultant obstetric anaesthetist, and the high-dependency team. Activate the multidisciplinary cardiac obstetric emergency pathway."
• "In parallel: sit her upright, give high-flow oxygen to maintain saturations above 95 per cent, left lateral tilt to relieve aortocaval compression, intravenous access, bloods including coagulation and troponin, ECG, and a bedside echocardiogram."^[1][7]
• "I would give intravenous furosemide for the pulmonary oedema, with small aliquots and reassessment because she is preload-dependent. I would start rate control with intravenous metoprolol or digoxin. I would not give a fluid bolus."^[1]

Examiner is listening for: the recognition of decompensation, the multidisciplinary call, the avoidance of fluid bolus, and the specific pharmacological therapy. ^[1]

Probe 1 — "Is the valve thrombosing?"

• "The mechanical click is present, which is reassuring against acute valve thrombosis. But I would arrange an urgent transthoracic echocardiogram and, if there is any concern, a transoesophageal echo to confirm valve function and exclude thrombus."^[2][6]
• "If valve thrombosis is identified, the treatment is intravenous unfractionated heparin with a target activated partial thromboplastin time in the high therapeutic range, or surgical embolectomy in the unstable patient. Thrombolysis carries maternal bleeding and fetal risks and is reserved for critically unwell patients."^[2][6]

Probe 2 — "She has been on warfarin. How does that change your anaesthetic plan?"

• "She took warfarin this morning, so her international normalised ratio is likely therapeutic. Neuraxial anaesthesia is contraindicated while the INR is elevated because of the risk of epidural haematoma."^[1]
• "I would check the INR and the coagulation profile now, and plan to reverse the warfarin if delivery is imminent. The transition is to stop warfarin, give intravenous unfractionated heparin to maintain anticoagulation, and stop the unfractionated heparin 4 to 6 hours before anticipated neuraxial insertion."^[1]
• "If delivery needs to happen before the anticoagulation can be reversed safely, that is a general anaesthetic. I would discuss the plan with the obstetric anaesthetist and the cardiologist now."^[1][8]

Probe 3 — "Should you deliver her now?"

• "The decision depends on her response to therapy and the fetal status. If she responds to diuresis and rate control with stabilisation of oxygen saturations and a falling heart rate, I would plan delivery in the next 24 to 48 hours under controlled conditions, with the anticoagulation transition."^[1]
• "If she does not respond, or if she deteriorates, the delivery becomes more urgent. Expedited delivery at 36+5 weeks is reasonable for a woman with cardiac decompensation that is not responding to therapy, and the fetal lungs are essentially mature."^[1]
• "I would involve the neonatal team because the baby is at 36+5 weeks and may need transitional care."^[1]

Probe 4 — "What is the postpartum plan?"

• "High-dependency or intensive care for 24 to 48 hours postpartum, because the postpartum haemodynamic surge is the highest-risk window. The ROPAC registry data confirm the markedly increased mortality and morbidity of mechanical-valve pregnancy overall."^[2]
• "Restart anticoagulation 4 to 6 hours after delivery with unfractionated heparin, transition back to LMWH, then warfarin from day 2 to 5 postpartum. Continue warfarin for at least 6 weeks postpartum given the high thrombosis risk of the puerperium."^[1]
• "Contraception counselling before discharge: progesterone-only options are preferred. Combined oral contraception is contraindicated in a mechanical valve because of the increased thrombosis risk."^[1]

Probe 5 — "How would you counsel her about future pregnancies?"

• "She has had one decompensating pregnancy with a mechanical valve. A future pregnancy will carry the same risks and she needs preconception counselling at the cardio-obstetric clinic."^[1]
• "Options to consider: replacement of the mechanical valve with a tissue valve (which does not require anticoagulation but has a shorter lifespan) before a future pregnancy, or proceeding with the same three-strategy anticoagulation framework with shared decision-making."^[1][5]
• "If she were to develop peripartum cardiomyopathy with persistent LV dysfunction, future pregnancy would be contraindicated. In this case the LV function is normal, so the advice is careful planning rather than avoidance."^[4]

Probe 6 — "Tell her what is happening, in language she will understand."

This is scored. Demonstrate it out loud rather than describing it. ^[1]

• Sit down, at her eye level, with her partner or support person present if she wishes.
• Plain words: "Your mechanical valve is working, but your heart is struggling with the extra work of late pregnancy. You have fluid building up in your lungs and your heart is racing in an irregular rhythm — and that is why you have been so short of breath."
• Stop and acknowledge: "This is a serious situation, and I have called in the heart and anaesthetic specialists to work with us tonight."
• The plan: "We are going to give you medicine to take the fluid off, medicine to slow your heart down, and oxygen to help you breathe. We are going to plan to deliver your baby in the next day or two, in a controlled way, with the right team in the room. We need to change your blood-thinning medication around the delivery to keep you safe."
• Outcome honesty: "You are in the best place for this. I will be honest with you about how you are doing as we go."
• Offer to call her support person, allocate a named midwife, and commit to a follow-up conversation.^[1]

Probe 7 — "What are the absolute contraindications to pregnancy in cardiac disease?"

• "Modified WHO class IV: pulmonary arterial hypertension of any cause, severe systemic ventricular dysfunction (ejection fraction under 30 per cent), severe symptomatic obstructive lesions such as severe mitral stenosis or severe aortic stenosis, severe aortic dilatation over 45 mm in Marfan syndrome, and native severe aortic coarctation."^[1]
• "These are the women who should be advised against pregnancy and offered reliable contraception. If pregnancy occurs, termination is offered."^[1]

Probe 8 — "What is peripartum cardiomyopathy and how is it different from what this woman has?"

• "Peripartum cardiomyopathy is heart failure with systolic dysfunction — most commonly an ejection fraction under 45 per cent — presenting in the last month of pregnancy or the first five months postpartum, with no other identifiable cause. It is treated with bromocriptine in addition to standard heart failure therapy, anticoagulation for severe cases, and is an absolute contraindication to subsequent pregnancy if LV function has not recovered."^[3][4]
• "This woman has decompensation of a known mechanical valve lesion, not peripartum cardiomyopathy. Her LV function is normal. The mechanism is the haemodynamic load of late pregnancy on a fixed-progression lesion, and the management is targeted at the haemodynamics and the valve rather than the cardiomyopathic LV."^[2][4]