FRCA Notes

Peripartum Cardiomyopathy

Resources

  • Peri-partum cardiomyopathy (PPCM) is an idiopathic variant of DCM defined by:
    1. Development of heart failure in the last month of pregnancy, or up to 5 months post-partum
    2. With LV systolic dysfunction on echocardiogram - LVEF <45%
    3. In the absence of pre-existing heart failure or another cause for heart failure

  • Incidence 1 in 1,000 live births, but with signficant ethnic variation
  • It is a diagnosis of exclusion

Maternal Pregnancy-associated
Age >30yrs Twin pregnancy
Afro-Caribbean origin Multiparous
Hypertension PET
Cocaine use Oral tocolytic therapy
Obesity


  • Poorly understood; definitely involves some genetic predisposition
  • Pregnancy is known to trigger a systemic, inflammatory-type response characterised by a balance of
    • Increased production of reactive oxygen species, predominantly by the placenta, which can cause oxidative stress
    • Increased total antioxidant capacity through upregulation of mitochondrial superoxide dismutase 2 (SOD2)

  • An imbalance of these factors is thought to be the pathophysiological mechanism of pre-eclampsia
  • Deregulation of the pathways protecting the heart from oxidative stress may lead to peripartum cardiomyopathy

  • In peripartum cardiomyopathy, oxidative stress leads to:
    • Increased production of an anti-angiogenic factor (soluble fms-like tyrosine kinase 1 [sFLT-1])
    • sFLT-1 is a a potent vascular endothelial growth factor inhibitor produced in the placenta, and raised levels are found in patients with peripartum cardiomyopathy

    • Abnormal protease function and cleavage of prolactin into a shorter N-terminal 16kDa prolactin fragment
    • Said fragment induces apoptosis, endothelial dysfunction and downregulates cardioprotective factors in the cardiac myocyte

Clinical features

  • Non-specific features of heart failure of varying severity
  • Variable clinical course, with both rapid-onset acute heart failure and insidous deterioration described
  • The majority experience NYHA III or IV symptoms
  • Two-thirds of patients present in the post-partum period

Differentials


CXR

  • May demonstrate features of heart failure e.g. cardiomegaly and pulmonary congestion
  • Helps exclude other causes of dyspnoea e.g. pneumonia, pleural effusions
  • A normal CXR does not exclude peripartum cardiomyopathy

ECG

  • Non-specific findings
  • Bundle branch block
  • ST-depression
  • T-wave inversion
  • Ectopic beats
  • Tachy- or brady-arrhythmias
  • Prolonged QTc (associated with an LVEF <35%)

TTE

  • Gold standard test
  • EF at presentation is <36% in two-thirds of cases and mean EF at presentation is 30%
  • There may be functional mitral regurgitation
  • Right heart dysfunction is a poor prognostic sign

Other

  • BNP and NT-pro-BNP are markedly increased, but non-specific to PPCM - they are normal or only marginally raised in normal pregnancy
  • Cardiac MRI may help exclude differentials such as myocarditis, infiltrative diseases or LV non-compaction cardiomyopathy
  • Hypertension and proteinuria should raise suspicion of pre-eclampsia

Peripartum management of the parturient with peripartum cardiomyopathy


  • Patients may be on hydralazine, as ACE-I/ARA/spironolactone are all contra-indicated
  • Both β-blockers and IV GTN can be safely given in pregnancy
  • Anticoagulation is recommended as there is a high risk of embolic events due to the combination of hypercoagulable state (pregnancy/post-partum) and LV systolic dysfunction
    • Need to time appropriately with regards to neuraxial intervention
  • Appropriate Cardiology, Obstetric and Anaesthetic input

  • In unstable disease patients may have delivery expedited

Monitoring

  • AAGBI as standard
  • Arterial line
  • May need more invasive haemodynamic monitoring

Haemodynamic goals

Cardiac feature Goal of anaesthetic management
Heart rate
Heart rhythm		 Avoid tachycardia
Maintain sinus rhythm with rapid treatment of arrhythmia
Preload Maintain adequate preload / normovolaemia
Left lateral tilt to avoid aortocaval compression
Avoid fluid overload; cautious fluids ± furosemide 1-20mg on delivery
Afterload Prevent increases in SVR
Maintain afterload i.e. avoid reduction in SVR by careful titration of neuraxial block
Contractility Avoid negative inotropy ± provide inotropic support
Other Intra-operative correction of deranged electrolytes
  • A carefully-titrated epidural/CSE is most appropriate, although can still be associated with gross haemodynamic compromise (as in this case series)

Drugs

  • Oxytocin when given as a rapid bolus can cause marked tachycardia, reduced SVR and reduced PVR
    • Therefore boluses are avoided and an infusion alone may be used

  • Ergometrine is avoided as it causes increased SVR, PVR and coronary vascular resistance
  • Carboprost should be avoided due to profound increase in PVR but reduced SVR

  • The autotransfusion and reduction in aortocaval compression post-delivery may precipitate decompensated heart failure

  • May be advised to avoid breastfeeding
    • Prolactin levels are thought to play a role in PPCM pathophysiology
    • Reduce levels by avoiding breastfeeding ± sometimes by prescribing bromocriptine

  • Likely to benefit from HDU care
  • Ongoing Cardiology follow-up