Peripartum Cardiomyopathy

• Idiopathic cardiomyopathy (a diagnosis of exclusion)
• Causes heart failure as a result of left ventricular systolic dysfunction
• In the last four weeks of pregnancy or first 5 months after pregnancy
• Over 60% present after the baby is born
• With no other cause of heart failure found
• Incidence 1:4000 live births
• Mortality 20–50%

• Not fully understood
• Behaves a lot like dilated cardiomyopathy
• Thought to be caused by a combination of genetic predisposition and the oxidative stress of pregnancy and labour
• Oxidative stress cleaves prolactin into a 16 kDa fragment
• This fragment then induces endothelial dysfunction and apoptosis leading to steadily worsening cardiac dysfunction

Break this down into pregnancy-specific, respiratory and cardiac causes of third trimester shortness of breath.

Pregnancy-specific

• Severe pre-eclampsia - Note this is usually diastolic failure
• Amniotic fluid embolism
• Pulmonary embolism
• Peripartum cardiomyopathy

Respiratory

• Obstructive -Asthma/COPD
• Restrictive - Interstitial lung disease/Cystic fibrosis
• Infective - Pneumonia

Cardiac

• Cardiomyopathy - dilated, restrictive, hypertrophic, takutsubo
• Ischaemic heart disease
• Myocarditis
• Valve disease
• Pulmonary hypertension
• Severe anaemia

Looks like left heart failure and it’s often heart to spot as shortness of breath and ankle swelling are common in pregnancy.

History

• Dyspnoea - on exertion and paroxysmal nocturnal dyspnoea*
• Palpitations
• Chest pain
• Dry cough
• It can have a rapid onset or take weeks to build

Non-specific ECG findings:

• Bundle branch block
• ST depression
• T wave inversion
• Arrhythmias
• QTc prolongation is associated with worse LV dysfunction

Chest xray may show:

• Cardiomegaly
• Pulmonary congestion
• But a normal CXR doesn’t exclude PPCM

Transthoracic echocardiography is the gold standard for PPCM diagnosis

• In over 60% of cases, the presenting LVEF is <36%
• Concomitant right heart dysfunction is a bad prognostic sign

Cardiac MRI can help exclude other causes but gadolinium should be avoided in pregnancy.

*BNP measurement is recommended for pregnant patients with orthopnoea or paroxysmal nocturnal dyspnoea. It is used to rule out cardiomyopathy, not to diagnose it.

• Previous peripartum cardiomyopathy
• Hypertension - pre-existing, gestational, pre-eclampsia
• Age >35
• Obesity
• Diabetes
• Twins or multiple pregnancy - hence IVF is a risk
• Family history
• Most common in women from Nigeria and Haiti

This is a clinical classification of severity of heart failure, depending on when a patient feels symptomatic.

• Class I - disease but no symptoms
• Class II - symptoms on exertion, mild impact on activity
• Class III - symptoms on minimal exertion
• Class IV - symptoms at rest

Supportive therapy, pharmacological and lifestyle interventions individualised to the woman’s gestation and condition by a specialised multidisciplinary team.

Loop diuretic

• To combat pulmonary oedema induced breathlessness

Beta blocker

• You can use metoprolol in pregnancy

Hydralazine

• If hypertensive

Low molecular weight heparin

• Reduced blood flow, mobility and pregnancy make her high risk for venous thromboembolism

Remember that ACEi and ARBs are contraindicated in pregnancy.

• Think about steroids if you’re anticipating early delivery
• Generally speaking over 70% will return to LVEF >50% within 6 months
• Consider ICD if LVEF still <35% at 6 months post delivery despite pharmacological treatment
• Future pregnancy is discouraged if LVEF <50%

• Previous PPCM
• LVEF <30%
• LV dilatation of more than 60mm
• Delayed diagnosis by more than a week
• RV dysfunction
• Prolonged QT
• LV thrombus
• Obesity
• African ethnicity

• Vaginal delivery with neuraxial analgesia is preferred where possible
• Clearly there are times when general anaesthesia is going to be necessary

• Ideally this is being managed in a specialist tertiary centre
• Early consultant involvement
• HDU/ITU input
• Invasive arterial monitoring
• Early epidural to reduce sympathetic surges during labour

Prepare for deterioration after delivery

This is caused by

• Rapid autobolus of 500ml blood from the uterus
• Sudden release of aortocaval compression
• These two can rapidly fluid overload a struggling heart
• Major haemorrhage will also be poorly tolerated by a cardiomyopathic heart

Your management priorities

• Optimise preload
• Adequate oxygenation
• Stabilise blood pressure
• Consider bromocriptine - D2 receptor agonist* adjunct for PPCM

*Inhibits prolactin release and therefore fewer nasty 16kDa fragments are formed. Appears promising but not heaps of evidence at present. Also prothrombotic so needs anticoagulation.

The standard approach still applies:

• Turn off the tap - Surgeon to kindly do please
• Replace blood with blood - But don’t fluid overload them, consider cell salvage as you normally might
• Uterotonics - However you need to be cautious about the effects your uterotonics are going to have on a delicate heart that’s already under a lot of stress

Oxytocin

• Reduces systemic vascular resistance (good)
• Induces a compensatory tachycardia (not good)
• Increase pulmonary vasoconstriction (not good)
• You can use it, but give it slowly via infusion, not as a bolus

Ergometrine

• Nope, not unless you’re absolutely stuck
• Increases systemic vascular resistance (not good)
• Induces coronary artery spasm (very not good)
• Emetogenic (not good)

Carboprost

• Also nope, unless desperate
• Increases pulmonary vascular resistance substantially (not good)

This is clearly only going to be feasible in specialist tertiary centres, and you essentially have three options, depending on the patient’s problem:

Cardiogenic shock

• Venoarterial extra-corporeal membrane oxygenation (ECMO)
• Carries enormous risk of complications for both mother and baby

Respiratory failure

• Veno-venous ECMO

Cardiac failure but without shock

• Left ventricular assist device (LVAD)
• Intra-aortic balloon pump

As always this is going to require specialised MDT input with regards to timings and mode of delivery and anticoagulation.