Mechanical Valve Replacement

Question 1

What are the maternal risks in a pregnancy complicated by mechanical valve replacement?

Answer 1

• Maternal mortality risk - 3%
• Valve failure
• Valve thrombosis
• Over and under coagulation
• Increased rate of pregnancy loss in the setting of warfarin use

Question 2

What are the fetal risks in pregnancy complicated by mechanical valve replacement?

Answer 2

• Increased rate of pregnancy loss in the setting of warfarin use
• Warfarin embryopathy - nasal hypoplasia, stippled epiphysis, optic atrophy, ACC, Dandy-Walker, MR

Question 3

How do you follow a patient in pregnancy with a history of mechanical valve replacement?

Answer 3

High risk for thromboembolism
- give therapeutic LMWH at 1mg/kg every 12 hours until 12 weeks of gestation in order to avoid warfarin embryopathy, risk is greater after 6 weeks and before 12 weeks) then switch to warfarin until 36 weeks then resume UFH or LMWH until delivery. Risk of fetal hemorrhage with warfarin after 12 weeks

• goal of INR is 3 (2.5-3.5).
• follow anti xa level for LMWH:
• trough goal predose : 0.6-0.7
• peak goal 4 hours after dose: 1.0 (0.7-1.2)

Give Coumadin through out pregnancy if patient has prior thromboembolism, older generation prosthesis at mitral location)

ADD ASPIRIN ALSO

Question 4

What are the most common cardiac complications occurring in pregnancy in a patient with a history of mechanical valve replacement?

Answer 4

• Maternal mortality risk - 3%
• Valve failure (can be independent of the pregnancy)
• Valve thrombosis
• Over and under coagulation
• Increased rate of pregnancy loss in the setting of warfarin use

Question 5

What are indications for c-section with maternal mechanical valve?

Answer 5

• Reserve c-section for usual obstetric indication

- Avoid operative delivery and iatrogenic lacerations

Question 6

How do you counsel a patient about the importance of anticoagulation in pregnancy with a mechanical valve replacement?

Answer 6

Anticoagulation needed to decrease risk of mechanical thrombosis which can cause embolic disease such as embolic stroke

Question 7

What are the options for anticoagulation in pregnancy with a mechanical valve replacement?

Answer 7

Aspirin 70-100mg daily ALSO

Option 1: Therapeutic LMWH 1mg/kg q 12h

• follow anti xa level for LMWH:
• trough goal predose : 0.6-0.7U/mL
• peak goal 4 hours after dose: 1.0U/mL (0.7-1.2)

Option 2: High dose UFH q12h

• follow anti xa level
• peak goal: 0.35 - 0.7U/mL
• follow aPTT
• peak goal: 2 times the control

Option 3: combination of 1 or 2 and warfarin - give therapeutic LMWH at 1mg/kg every 12 hours until 12 weeks of gestation in order to avoid warfarin embryopathy, risk is greater after 6 weeks and before 12 weeks) then switch to warfarin until 36 weeks then resume UFH or LMWH until delivery. Risk of fetal hemorrhage with warfarin after 12 weeks

• goal of INR is 3 (2.5-3.5).
• follow anti xa level for LMWH:
• trough goal predose : 0.6-0.7
• peak goal 4 hours after dose: 1.0 (0.7-1.2)

Option 4: warfarin the entire pregnancy until close to delivery
-goal of INR is 3 (2.5-3.5).

Question 8

What are the risks and benefits of warfarin therapy for patients with mechanical valve?

Answer 8

Benefits:
-Effective anticoagulation

Risks:
-Warfarin embryopathy (nasal bone hypoplasia, stippled epiphysis, dandy walker, absent corpus callosum, optic atrophy, MR, IUGR)

Question 9

For pregnancy woman with mechanical valve and therapeutic anticoagulation, describe how you will manage her anticoagulation around the time of delivery.

Answer 9

Switch to UFH at 36 weeks
Discontinue UFH 4-6 hours before delivery
Resume anticoagulation 4-6 hours postpartum