Cardiac disease in pregnancy

Surgical approach (obstetric/cardiac pathways)

• Most cases are not a single operation; management centres on mode/timing of delivery and multidisciplinary planning (obstetrics, cardiology, anaesthesia, ICU, neonatology).
  • Preferred: vaginal delivery with assisted second stage (forceps/ventouse) to reduce Valsalva where appropriate.
  • Caesarean section (CS) for obstetric indications or selected cardiac indications (e.g. severe aortic stenosis with decompensation, acute aortic dissection, severe pulmonary hypertension, anticoagulation issues with mechanical valves, inability to tolerate labour).
  • Invasive monitoring/lines: arterial line often before neuraxial for high-risk lesions; central access if vasoactive infusions anticipated (balance against thrombosis/infection).
  • Post-delivery: active management of third stage (avoid large haemodynamic swings), careful uterotonic choice, and planned HDU/ICU observation (often 24–72 h).

Anaesthetic management (overview for labour analgesia and CS)

• Type of anaesthesia: Regional preferred in most (labour epidural; CS incremental epidural/CSE). GA reserved for specific indications (urgent CS, contraindication to neuraxial, severe decompensation, aortic dissection, inability to lie flat, anticoagulation).
  • Labour: early epidural analgesia to blunt sympathetic surges; avoid sudden SVR drop (incremental dosing).
  • CS: incremental epidural or low-dose CSE; avoid single-shot spinal in fixed-output lesions (severe AS/MS, severe pulmonary HTN) due to abrupt sympathectomy.
• Airway: if GA, ETT (RSI). SGA generally avoided for CS and high-risk cardiac disease due to aspiration risk and need for controlled ventilation/afterload control.
• Duration: labour variable; CS typically 45–90 min (longer if complex/PPH).
• Pain: labour moderate–severe; CS postoperative pain moderate. Use multimodal (paracetamol ± NSAID if appropriate, neuraxial opioid, wound infiltration/TAP if needed).
• Haemodynamic goals: lesion-specific but generally avoid tachycardia, maintain preload, avoid sudden SVR changes, maintain oxygenation and acid–base, treat arrhythmias promptly.
• Vasopressors: phenylephrine useful where SVR support needed and tachycardia undesirable; metaraminol acceptable; ephedrine may worsen tachycardia/arrhythmias. In RV failure/pulmonary HTN consider norepinephrine/vasopressin and inotropes (dobutamine/milrinone) with specialist input.
• Uterotonics: oxytocin slow/infusion (avoid bolus). Avoid/limit ergometrine (↑SVR, coronary spasm, pulmonary vasoconstriction). Carboprost can worsen pulmonary HTN/bronchospasm; misoprostol often safer haemodynamically.
• Postpartum: highest risk period (autotransfusion, fluid shifts). Plan HDU/ICU, cautious fluids/diuresis, thromboprophylaxis, early mobilisation, and clear escalation plan.

Why pregnancy stresses the heart (physiology you must quote)

• Cardiac output increases by ~30–50% (HR +10–20 bpm and SV ↑). Peaks by mid-pregnancy; further rises during labour and immediately postpartum (autotransfusion).
• Systemic vascular resistance falls (progesterone/placental circulation) → may worsen right-to-left shunts (↓SVR increases shunt fraction).
• Plasma volume ↑ ~40–50%; RBC mass ↑ less → physiological anaemia; increases risk of pulmonary oedema in stenotic lesions.
• Aortocaval compression reduces venous return in supine position → hypotension, reduced uteroplacental perfusion; important in fixed-output lesions.
• Hypercoagulable state (↑fibrinogen, factors VII/VIII/X; ↓protein S) → thrombosis risk, especially with mechanical valves and atrial arrhythmias.
• Labour: pain/anxiety ↑ catecholamines (tachycardia, ↑SVR). Each contraction autotransfuses ~300–500 mL; second stage Valsalva increases afterload and venous return swings.
• Postpartum: greatest haemodynamic load in first 24–72 h (relief of IVC compression + uterine involution autotransfusion) → pulmonary oedema/arrhythmias/decompensation.

Risk stratification and planning (what to say in viva)

• Use mWHO maternal cardiovascular risk classification to guide counselling, place of delivery, and monitoring (I–IV).
  • mWHO IV (pregnancy contraindicated/very high risk): pulmonary arterial hypertension, severe systemic ventricular dysfunction (EF <30%/NYHA III–IV), severe MS/AS, Marfan with aorta >45 mm, prior peripartum cardiomyopathy with residual impairment, severe coarctation.
• Functional status predicts outcome: NYHA class, exercise tolerance, oxygen saturations, prior cardiac events, BNP/NT-proBNP, echo findings (valve gradients, ventricular function, pulmonary pressures).
• Red flags for decompensation: resting tachycardia, orthopnoea/PND, syncope, cyanosis, new murmur, pulmonary oedema, rising BNP, worsening RV function.
• Delivery planning: timing (often 37–39 weeks if stable), location (tertiary centre for high risk), analgesia plan, monitoring plan, anticoagulation plan, uterotonic plan, PPH plan, and postpartum bed.
• Monitoring: low risk—standard; higher risk—arterial line, strict fluid balance, early echo access; consider CVP only if it will change management (poor correlation with LV filling).

Lesion-specific haemodynamic goals (high-yield table in words)

• Stenotic lesions (MS/AS): fixed output → maintain preload, maintain sinus rhythm, avoid tachycardia, avoid hypotension; treat AF promptly; avoid sudden sympathectomy.
• Regurgitant lesions (MR/AR): tolerate pregnancy better; aim for mild tachycardia, avoid bradycardia, avoid ↑SVR, maintain forward flow; neuraxial often beneficial if gradual.
• Pulmonary hypertension / Eisenmenger: avoid ↑PVR (hypoxia, hypercarbia, acidosis, pain, hypothermia), avoid ↓SVR, maintain RV perfusion; consider invasive monitoring, ICU, and avoid emboli/air.
• Cardiomyopathy/HF: avoid fluid overload, maintain perfusion pressure, early diuresis, consider inotropes/vasodilators; neuraxial carefully titrated; postpartum highest risk.
• Aortopathy (Marfan/BAV/aortic aneurysm): avoid hypertension and tachycardia; gentle laryngoscopy if GA; consider early epidural; avoid pushing/consider assisted delivery.

Common cardiac conditions in pregnancy (key points)

• Mitral stenosis (often rheumatic): pregnancy increases HR/volume → ↑LA pressure → pulmonary oedema; AF poorly tolerated.
  • Goals: slow HR, maintain preload (but avoid overload), maintain SVR, treat AF (rate control ± cardioversion), diuretics for congestion.
  • Anaesthesia: early epidural; avoid tachycardia (pain, ephedrine); phenylephrine often preferred; avoid single-shot spinal if severe.
• Aortic stenosis (often congenital BAV): fixed output; syncope/angina/dyspnoea = severe; risk of collapse with ↓SVR.
  • Goals: maintain SVR, maintain preload, avoid tachycardia, maintain sinus rhythm; treat hypotension promptly with vasoconstrictor.
  • Anaesthesia: incremental epidural/CSE; avoid rapid sympathectomy; consider GA with invasive monitoring if unstable/urgent.
• Regurgitant valve disease (MR/AR): usually tolerated; risk if LV dysfunction/PAH.
  • Goals: avoid bradycardia and ↑SVR; neuraxial helpful if gradual; treat HF with diuretics/vasodilators as appropriate.
• Mechanical heart valves: maternal thrombosis risk high; anticoagulation complex; neuraxial depends on anticoagulant timing.
  • Anticoagulation strategies (specialist-led): LMWH with anti-Xa monitoring, UFH near delivery, or warfarin (teratogenic early; fetal bleeding risk). Delivery plan must specify stop times and bridging.
  • Anaesthetic implication: neuraxial only if anticoagulation safely held per ASRA/RA-UK guidance and coagulation normal; otherwise GA may be required.
• Congenital heart disease: increasing prevalence; understand shunts and PVR/SVR effects.
  • Left-to-right shunts (ASD/VSD/PDA): usually tolerated unless pulmonary HTN develops; avoid air embolism (filters).
  • Right-to-left shunts/Eisenmenger: very high maternal mortality; avoid ↓SVR and ↑PVR; consider early epidural with extreme caution; many recommend avoiding pregnancy.
• Pulmonary arterial hypertension (PAH): among highest-risk conditions; RV failure, sudden death postpartum.
  • Management: tertiary centre, ICU, oxygen, avoid hypovolaemia/hypervolaemia, consider pulmonary vasodilators (inhaled NO, prostacyclin) and vasopressors that support SVR without tachycardia (vasopressin/norepi).
• Peripartum cardiomyopathy: HF developing late pregnancy to months postpartum; risk of arrhythmia/thromboembolism.
  • Treat as acute HF (oxygen, diuretics, vasodilators, inotropes if shock). Anticoagulate if severe LV dysfunction. Avoid subsequent pregnancy if persistent LV impairment.
• Ischaemic heart disease/SCAD (spontaneous coronary artery dissection): rare but important; consider in chest pain; manage with cardiology; avoid thrombolysis if dissection suspected.
• Arrhythmias: SVT/AF more common; treat triggers (pain, hypoxia, sepsis).
  • Acute SVT: vagal manoeuvres → adenosine safe; beta-blockers (e.g. metoprolol) often used; cardioversion safe if unstable.
  • AF with MS: urgent rate control and anticoagulation; consider cardioversion if unstable.

Labour analgesia and delivery: practical anaesthetic plan

• Early assessment: symptoms (NYHA), vitals, ECG, recent echo, anticoagulation status, airway, baseline sats; confirm delivery plan and escalation triggers.
• Analgesia: early epidural with low-concentration local anaesthetic + opioid; avoid dense motor block if it worsens venous return; maintain left uterine displacement.
• Second stage: consider assisted delivery to reduce Valsalva in stenotic lesions, PAH, aortopathy, severe HF.
• Third stage: oxytocin slow (e.g. 1–3 IU slowly then infusion per local policy); avoid ergometrine in many cardiac lesions; prepare for PPH with a haemodynamically safe plan.
• Fluids: avoid routine boluses; use small aliquots guided by BP/clinical signs; consider diuretics early postpartum in HF/stenosis.
• Monitoring: continuous ECG, pulse oximetry; arterial line for severe lesions; consider delivery in theatre for rapid conversion and monitoring.

Caesarean section: neuraxial vs GA (decision points)

• Neuraxial (preferred in many): incremental epidural or low-dose CSE reduces catecholamines, allows awake mother, avoids airway/pressor response; requires meticulous BP control.
• Avoid single-shot spinal in: severe AS, severe MS, severe PAH/Eisenmenger, severe cardiomyopathy with marginal perfusion (risk of precipitous ↓SVR).
• GA indications: urgent fetal/maternal compromise, anticoagulated patient, failed neuraxial, inability to tolerate supine position, aortic dissection, severe decompensation requiring controlled ventilation/inotropes.
• GA conduct: arterial line pre-induction if time; gentle induction to avoid tachycardia/hypertension; consider opioid/short-acting beta-blocker; avoid hypoxia/hypercarbia; maintain SVR (phenylephrine/norepi as appropriate).

Endocarditis prophylaxis and antibiotics (exam nuance)

• Routine antibiotic prophylaxis for infective endocarditis is not recommended for uncomplicated vaginal delivery/CS in most guidelines; consider only in highest-risk patients undergoing high-risk procedures (specialist decision).
  • Highest risk typically includes: prior infective endocarditis, prosthetic valves, certain cyanotic congenital heart diseases.

Drugs in pregnancy/lactation (high-yield list)

• Generally used: beta-blockers (watch fetal growth), diuretics, digoxin, adenosine, heparins (LMWH/UFH).
• Avoid/limited: ACE inhibitors/ARBs (fetotoxic), warfarin (teratogenic 1st trimester; fetal bleeding), amiodarone (fetal thyroid effects; use if life-threatening).
• Magnesium sulfate (for eclampsia) can potentiate neuromuscular blockade and cause vasodilation; caution in severe AS/MS and when using NMBAs.