Cardiac disease in pregnancy

List:

· Cardiovascular changes

· General principles

· Mortality risk

· Specific diseases

Pregnancy	· ↑Cardiac output (↑50% by end T2) – HR and SV · ↓SVR (↓30% by end T1) · ↑Blood volume (↑50% by end T2) – RBCs and plasma · ↑Coagulability · Supine aortocaval compression · ±Hypertensive disorders of pregnancy: ↑SVR
Labour	· ↑↑Cardiac output: pain + anxiety + contractions · Valsalva manoeuvre
Post-partum	· ↑↑↑Cardiac output (80% above term baseline) · Autotransfusion vs PPH · Relief of aortocaval compression · High of decompensation for several hours
Iatrogenic	· IV fluid: ↑preload, ↑risk APO · Oxytocics: oxytocin ↓SVR, ergot/PGF₂_α ↑↑SVR, ↑PVR

Model of care	· Tertiary centre · Obstetrician-led · Multi-disciplinary: O&G + paeds + cardiology + anaesthesia + ICU · Frequent review · Clear birth plan
Serial assessments	Changes are progressive – may be ok in T1 but not in T3 · History: chest pain, dyspnoea, orthopnoea · Examination: volume status, foetal well-being · Investigations: ECG, serial TTE, MRI
Risk stratification	Highest risk: · Pulmonary hypertension · Peripartum cardiomyopathy · Fixed output lesion = intolerance of high venous return · Dilated aorta = risk of pop · Severe anything CARPREG score: · Prior cardiac event (AMI, APO, arrhythmia, stroke) · Baseline impairment (NYHA 3+, cyanosis) · Left heart obstruction (MS, AS, HCM) · LV systolic dysfunction (EF)
Optimisation	· Medication: e.g. beta blocker · Surgery: e.g. balloon valvuloplasty, myotomy · Balance risks to mother vs foetus · Beware teratogens, esp warfarin (T1), ACEi/ARB, amiodarone

Obstetrics

· Default: IOL @ 39+2, early epidural, instrumental, no pushing

· When: term vs premature, prefer in-hours

· Where: tertiary centre, labour ward vs ICU

· What: VD vs CS, spont vs IOL, push vs instrumental, ±epidural

· Why: risk of lesion (e.g. APO vs pop)

Critical care

· Pressure monitoring: A-line vs NIBP

· Venous access: PIVC vs CVC

Medications

· Oxytocics: ergotamine contraindicated for things that go ‘pop’

· Antibiotics: if abnormal valve, some congenital disease

· Anticoagulants: continue vs bridge vs cease

· Vasoactives: β-blocker vs vasopressor vs inotrope

Ischaemic heart Dx	· Usual risk factors · Best treatment is balloon angioplasty · Avoid anti-platelet + thrombolysis
Aortic stenosis	· Cannot handle ↑↑venous return · Ante-partum: balloon dilatation only if severe · Intra-partum: ↔SVR, ↔HR, sinus rhythm
Aortic dilatation	· e.g. Marfan’s syndrome, association with bicuspid valve · Risk of aortic dissection · Worse with contractions + pushing · Worse with PET · Ante-partum: TTE every 1-2 months · Planning: timing dependent upon a) diameter b) rate of change · Intra-partum: aim ↔HR, ↔SVR, ↔SBP, no pushing · ? Labour epidural + instrumental delivery + no pushing
Mitral stenosis	· High mortality · Rheumatic disease: Aborigines, overseas-born · Risk: ↑↑Venous return -> APO · Ante-partum: β-blocker, anticoag, ±balloon dilatation · Intra-partum: limit IV fluid
Pulmonary HTN	· Very high mortality (50%!) · Intra-partum: elective GA – cardiac anaes + O&G anaes
Fontan circulation	· Single ventricle (usually RV – not designed for high workload) · Low venous return -> low cardiac output -> low oxygen delivery · High systemic venous pressure · Risks to mother: arrhythmia, heart failure, VTE, PPH · Risks to foetus: miscarriage+++, IUGR, prematurity
Prosthetic valves	· Aspirin, UFH and LMWH are safe · Warfarin is not