Heart disease in pregnancy

O99.4 + (S151.9)

All women with heart disease require referral for specialist evaluation and risk assessment. The risk is particularly high in women with mechanical valves, Eisenmenger’s syndrome or pulmonary hypertension. Termination of pregnancy (TOP) is an option for women with severe heart disease if recommended by a specialist .

GENERAL MEASURES

All pregnant women with haemodynamically significant heart disease require multidisciplinary management in consultation with both obstetrician and physician/cardiologist.
Consider thyrotoxicosis, anaemia and infection, which may precipitate cardiac failure.
Spontaneous delivery is usually preferable to Caesarean delivery, unless there are obstetric reasons for surgery.
Women with prosthetic heart valves should be counselled about the risks of pregnancy to themselves and fetus; and offered effective contraception .

During labour:

  • Nurse in semi-Fowler’s position.
  • Avoid unnecessary intravenous fluids.
  • Give adequate analgesia.
  • Antibiotic prophylaxis for infective endocarditis, guided by the nature of the heart lesion (for cardiac indications and antibiotic recommendations see Endocarditis, Infective). Procedures for which endocarditis prophylaxis is indicated include :
    • Vaginal delivery in the presence of suspected infection.
    • Caesarean section.
    • Assisted vaginal delivery.
    • Prelabour rupture of membranes.
  • Avoid a prolonged second stage of labour by means of assisted delivery with forceps (preferably) or ventouse.
  • Avoid ergometrine after delivery of the newborn.
  • Observe in a high care area for 24 hours post-delivery, as the risk of pulmonary oedema is highest in this period.

Contraception, including the option of tubal ligation should be discussed during the antenatal period and after delivery in all women with significant heart disease.
Women who had life-threatening complications during pregnancy should be advised not to become pregnant again .

Anticoagulation during pregnancy:

Indications for full anticoagulation during pregnancy (high risk):

  • Valvular disease with atrial fibrillation: Women with valvular heart disease should be guided to consider completing their family early and then consider family planning including tubal ligation, before progressing to requiring mechanical valves.
  • Mechanical prosthetic heart valves: Women with mechanical prosthetic heart valves should be offered contraception (preferably a LARC not containing estrogen); see PHC STGs and EML: Family planning. If they conceive, offer the option of TOP or refer to tertiary centre for anticoagulation management by a multi-disciplinary team

MEDICINE TREATMENT

For pregnant women with valvular disease and atrial fibrillation:

First trimester

  • Enoxaparin SC, 1 mg/kg 12 hourly.

OR

  • Unfractionated heparin, IV, 5 000 units as a bolus.
    • Followed by 1 000–1 200 units/hour as an infusion.

OR

  • Unfractionated heparin, SC, 15 000 units 12 hourly.
    • Adjust the dose to achieve a mid-target PTT at 2–3 x control..

Practise strict infection control if using multi-dose vials, with one vial per patient and use of needle-free adaptor.

Second trimester until 36 weeks

  • Warfarin, oral, 5 mg daily.
    • Adjust dose to keep INR within the therapeutic range of 2–3 .

After 36 weeks until delivery

  • Enoxaparin SC, 1 mg/kg 12 hourly.

OR

  • Unfractionated heparin, IV, 5 000 units as a bolus.
    • Followed by 1 000–1 200 units/hour as an infusion.

OR

  • Unfractionated heparin, SC, 15 000 units 12 hourly.
    • Adjust dose with aPTT to keep it 2–3 x control .

Delivery

Stop heparin on the morning of elective Caesarean delivery (6 hours before scheduled surgery) or when in established labour, and re-start 6 hours after vaginal delivery or 12 hours after Caesarean delivery, as long as there is no concern that the patient is bleeding.

Secondary prophylaxis for venous thromboembolism Z29.9

  • More than one previous episode of venous thromboembolism.
  • One previous episode without a predisposing factor, or evidence of thrombophilia.
    • Low molecular weight heparin, e.g.:
    • Enoxaparin, SC, 40 mg daily.

LoEI [8]

OR

  • Unfractionated heparin, SC, 5 000 units 12 hourly.

LoEI [9]

Cardiac failure O99.4 + (I50.9)

See Congestive Cardiac Failure .
Treatment is as for non-pregnant women, except that ACE-inhibitors and ARBs and spironolactone are contra-indicated.

LoEIII [10]

If a vasodilator is needed:

  • Hydralazine, oral, 25 mg 8 hourly.
    • Maximum dose: 200 mg daily.

AND

  • Isosorbide dinitrate, oral, 20 mg 12 hourly.
    • Maximum dose: 160 mg daily.

Delivery O99.4 + (I50.0)

Contraction and retraction of the uterus after delivery increases the total peripheral resistance, and causes a relative increase in circulating volume. This may precipitate pulmonary oedema .

In women with NYHA grade II dyspnoea or more, consider the use of furosemide:

  • Furosemide, IV, 40 mg with delivery of the baby.
    • Monitor for 48 hours thereafter for pulmonary oedema.

REFERRAL

  • All pregnant women with mechanical prosthetic heart valves requiring anticoagulation.

Pregnant women with mechanical prosthetic valves should not receive LMWH unless antifactor Xa levels can be monitored reliably weekly. Therapeutic range is pre-dosing level 0.6 units/mL and a 4-hour peak level of 1–1.2 units/mL