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How to Treat Heart Disease In Pregnancy?


Things to note:
  • Consider thyrotoxicosis, anaemia and infection, which may precipitate cardiac failure.
  • Spontaneous delivery is usually preferable to Caesarean section, unless there are obstetric reasons for surgery.
  • Nurse in semi-Fowlers position. Avoid unnecessary intravenous fluids.
  • Avoid a prolonged second stage of labour by means of assisted delivery with forceps (preferably) or ventouse.
  • Contraception, including the option of tubal ligation should be discussed after delivery in all women with significant heart disease.
  • Women who had serious complications during pregnancy should be advised not to become pregnant again.

Medical Treatment:
Indications for full anticoagulation during pregnancy (high risk):
  • Valvular disease with atrial fibrillation
  • Women with prosthetic heart valves
Pregnant women with prosthetic mechanical valves should not receive LMWH unless antifactor Xa levels can be monitored reliably weekly. Pre-dosing level 0.6 units/mL and a 4-hour peak level of 1-1.2 units/mL.
First trimester
  • 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 aPTT 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
  • Warfarin, oral, 5 mg daily.
    • Control with INR to keep within the therapeutic range of 2.5-3.5.
After 36 weeks until delivery
  • 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.
    • Stop heparin on the morning of elective Caesarean section or when in established labour, and re-start 6 hours after vaginal delivery or 12 hours after Caesarean section.
Consider the use of warfarin throughout pregnancy for women with older generation mechanical valves, or valves in the mitral position.
Prophylaxis for venous thromboembolism
  • More than one previous episode of venous thromboembolism.
  • One previous episode without a predisposing factor, or with evidence of thrombophilia.
Low molecular weight heparin, e.g: dalteparin, SC, 5000 units daily.
OR
  • Unfractionated heparin, SC, 5 000 units 8 hourly.
  • Treat accompanying complications, e.g. cardiac failure.
Antibiotic therapy
  • It is essential to do at least three and no more than six blood cultures taken by separate venipunctures before starting antibiotics.
  • In patients with subacute presentation and no haemodynamic compromise, wait for the results before starting antibiotics.
  • Empiric treatment is indicated in patients with a rapidly fulminant course or with severe disease only.
  • Aminoglycoside therapy should be monitored with trough levels for safety.
  • Duration of therapy given is the minimum and may be extended based on the response (clinical and laboratory).
  • In penicillin-allergic patients vancomycin is the antibiotic of choice.
Empiric therapy
Native valve
  • Benzylpenicillin (penicillin G), IV, 5 million units 6 hourly for 4 weeks
PLUS
  • Gentamicin, IV, 1.5 mg/kg 12 hourly for 2 weeks If staphylococcal infection is suspected (acute onset):
ADD
  • Cloxacillin, IV, 3 g 6 hourly.
Prosthetic valve*
  • Vancomycin, IV, 15 mg/kg 12 hourly for 6 weeks.
PLUS
  • Rifampicin, oral, 7.5 mg/kg 12 hourly for 6 weeks.
PLUS
  • Gentamicin, IV, 1.5 mg/kg 12 hourly for 2 weeks.
All cases of prosthetic valve endocarditis should be managed in consultation with an appropriate specialist.
Directed therapy (native valve)
Streptococcal

Fully susceptible to penicillin MIC: < 0.2mg/L
  • Benzylpenicillin (penicillin G), IV, 5 million units 6 hourly for 4 weeks.
Moderately susceptible MIC: 0.12-0.5 mg/L
  • Benzylpenicillin (penicillin G), IV, 5 million units 6 hourly for 4 weeks.
PLUS
  • Gentamicin, IV, 1.5 mg/kg 12 hourly for 2 weeks.
Moderately resistant MIC: 0.5-4mg/L Enterococci and Abiotrophia spp. (nutritionally variant streptococci)
  • Benzylpenicillin (penicillin G), IV, 5 million units 6 hourly for 4 weeks.
PLUS
  • Gentamicin, IV, 1.5 mg/kg 12 hourly for 4 weeks. Six weeks of therapy may be required in cases with a history of > 3 months, or mitral or prosthetic valve involvement.
Fully resistant MIC: > 4 mg/L
  • Vancomycin, IV, 15 mg/kg 12 hourly for 6 weeks.
PLUS
  • Gentamicin, IV, 1.5 mg/kg 12 hourly for 6 weeks.
Enterococcal
Fully susceptible to penicillin MIC: < 4mg/L
  • Benzylpenicillin (penicillin G), IV, 5 million units 6 hourly for 4 weeks.
Resistant to penicillin MIC 4mg/L or significant -lactam allergy and Sensitive to vancomycin MIC: 4 mg/L
  • Consult a specialist.
Staphylococcal (cloxacillin/methicillin sensitive)
S. aureus
    • Cloxacillin, IV, 3 g 6 hourly for 4 weeks. If necessary,
      add:
    • Gentamicin, IV, 5 mg/kg daily for the first 3-5 days.
  • The benefit of adding an aminoglycoside has not been established.
  • In the rare occurrence of a penicillin sensitive staphylococcus, penicillin should be used in preference to cloxacillin.
Coagulasenegative staphylococci
  • Consult expert opinion on correct diagnosis in this setting.
Staphylococcal (cloxacillin/methicillin resistant) or methicillin sensitive with significant beta-lactam allergy
S. aureus
  • Vancomycin, IV, 15 mg/kg 12 hourly for 4 weeks.
Coagulasenegative staphylococci
  • Consult expert on correct on antibiotic choice.
Directed therapy for prosthetic valve endocarditis
  • Duration of therapy is usually a minimum of at least 6 weeks.
  • Seek expert opinion on antibiotic choice.
Endocarditis prophylaxis
Cardiac conditions
Patients with the following cardiac conditions are at risk of developing infective endocarditis:
  • Acquired valvular heart disease with stenosis or regurgitation.
  • Prosthetic heart valves.
  • Structural congenital heart disease, including surgically corrected or palliated structural conditions, but excluding isolated atrial septal defect, fully repaired ventricular septal defect or fully repaired patent ductus arteriosus.
  • Previous endocarditis.
Procedures requiring prophylaxis
  • Antibiotic prophylaxis is recommended for all dental procedures that involve manipulation of either the gingival tissue or the peri-apical region of the teeth.
  • Antibiotic prophylaxis is not recommended for patients who undergo a gastro-intestinal or genito-urinary procedure.
Prophylaxis
  • Maintain good dental health.
  • This is the most important aspect of prophylaxis.
  • Refer all patients to a dental clinic/dental therapist for assessment and ongoing dental care.
    • Amoxicillin, oral, 2 g one hour before the procedure.
Penicillin allergy:
  • Clindamycin, oral, 600 mg one hour before the procedure.
If patient cannot take oral:
  • Ampicillin, IV/IM, 2 g one hour before the procedure.
Penicillin allergy:
  • Clindamycin IM/IV, 600 mg 1 one hour before the procedure.
The NICE review noted the lack of a consistent association between interventional procedures and development of infective endocarditis, and that the efficacy of antibiotic prophylaxis is unproven. It further commented that because the antibiotic is not without risk, there is a potential for a greater mortality from severe hypersensitivity than from withholding antibiotics.
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.
Cardiac failure
  • Mortality is significantly reduced by the use of ACE inhibitors, Beta-blockers and spironolactone in heart failure.
  • Digoxin has been shown to reduce hospitalisation only.
Diuretic
Mild volume overload (mild CCF) and normal renal function, thiazide diuretic:
  • Hydrochlorothiazide, oral, 25-50 mg daily.
    • Caution in patients with gout.
    • Contraindicated in impaired renal function.
Significant volume overload or abnormal renal or hepatic function, loop diuretic:
  • Furosemide, oral, daily.
    • Initial dose: 40 mg/day.
    • Higher dosages may be needed, especially if also renal failure.
Note:
  • Unless patient is clinically fluid overloaded, reduce the dose of diuretics before adding an ACE inhibitor.
  • After introduction of an ACE inhibitor, try to reduce diuretic dose and consider a change to hydrochlorothiazide.
  • Routine use of potassium supplements with diuretics is not recommended. They should be used short term only, to correct documented low serum potassium level.
ACE inhibitor, e.g:
  • Enalapril, oral, 2.5 mg 12 hourly up to 10 mg 12 hourly.
If ACE inhibitor intolerant, i.e. intractable cough:
  • Angiotensin receptor blocker (ARB), e.g:
    • Losartan, oral, 50-100 mg daily. (Specialist initiated)
Spironolactone
  • Use with an ACE inhibitor in patients presenting with Class III or IV heart failure.
  • Do not use if GFR <30 mL/minute.
  • Monitoring of potassium levels is essential if spironolactone is used with an ACE inhibitor or other potassium sparing agent or in the elderly.
    • Spironolactone, oral, 25 mg once daily.
Beta-blockers
  • For all stable patients with heart failure who tolerate it.
  • Patients should not be fluid overloaded or have low blood pressure before initiation of therapy.
Carvedilol, oral.
  • Initial dose: 3.125 mg daily.
  • Increase after two weeks to 3.125 g 12 hourly, if tolerated.
  • Increase at two-weekly intervals by doubling the daily dose until a maximum of 25 mg 12 hourly, if tolerated.
  • If not tolerated, i.e. worsening of cardiac failure symptoms, reduce the dose to the previously tolerated dose.
  • Up-titration can take several months.
Digoxin
Symptomatic CCF owing to systolic dysfunction.
  • Digoxin, oral, 0.125 mg daily. Specialist initiated.
    • Digoxin trough blood levels (before the morning dose) should be maintained between 0.65 and 1.5 nmol/L
    • Patients at high risk of digoxin toxicity are:
      1. the elderly,
      2. patients with poor renal function,
      3. hypokalaemia, and
      4. patients with low body weight.
Anticoagulants
  • Heparin for DVT prophylaxis.
For patients admitted to hospital, unless contraindicated:
  • Unfractionated heparin, SC, 5 000 units 8 hourly.
Warfarin: Narrow QRS complex (supraventricular) tachydysrhythmias
  • Poor rate control.
  • Severe symptoms.
  • Warfarin, oral, 5 mg daily.
    • Control with INR to therapeutic range, i.e. between 2.0 and 2.5.
Anti-dysrhythmic drugs
  • Exclude underlying structural cardiac disease in all patients with cardiac dysrhythmias.
  • Only for potentially life-threatening ventricular dysrythmias.
  • Always exclude electrolyte abnormalities and drug toxicity first.
Thiamine
Consider in all unexplained heart failure.
  • Thiamine, oral/IM, 100 mg daily.
  • Treatment is as for non-pregnant women, except that ACE-inhibitors and ARBs are contra-indicated.
If a vasodilator is needed:
  • Hydralazine, oral, 25 mg 8 hourly.
    • Maximum dose: 200 mg daily.
PLUS
  • Isosorbide dinitrate, oral, 20 mg 12 hourly.
    • Maximum dose: 160 mg daily.
Delivery
  • 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.