Anticoagulation for Pregnant Women With Mechanical Prosthetic Heart Valves

Vocabulary flashcards covering guidelines, dosages, monitoring parameters, and delivery transition protocols for anticoagulation in pregnant women with mechanical prosthetic heart valves.

Vitamin K Antagonist (VKA) in Pregnancy

An anticoagulation strategy associated with the lowest likelihood of maternal complications but highest likelihood of miscarriage, fetal death, and congenital abnormalities, particularly if taken during the first trimester and if warfarin dose exceeds $5\,\text{mg/d}$.

Warfarin Pre-Delivery Switch Protocol

Pregnant women with mechanical valve prostheses on warfarin should switch to twice-daily LMWH (with target anti-Xa level of $0.8\,\text{U/mL}$ to $1.2\,\text{U/mL}$ at 4 to 6 hours after dose) or intravenous UFH (aPTT $2\,\text{times control}$) at least 1 week before planned delivery.

LMWH to UFH Pre-Delivery Switch Timing

Pregnant women with mechanical valve prostheses on LMWH should switch to UFH (with an aPTT $2\,\text{times control}$) at least 36 hours before planned delivery.

UFH Cessation Before Vaginal Delivery

Pregnant women with valve prostheses should stop UFH at least 6 hours before planned vaginal delivery.

Delivery Strategy on Therapeutic VKA

If labor begins or urgent delivery is required in a woman therapeutically anticoagulated with a VKA, cesarean section should be performed after reversal of anticoagulation.

Low-Dose Warfarin Regimen ($\le 5\,\text{mg/d}$)

For pregnant women with mechanical prostheses who require a dose of warfarin $\le 5\,\text{mg/d}$ to maintain a therapeutic INR, continuation of warfarin for all 3 trimesters is reasonable (COR 2a, LOE B-NR) after full discussion of risks and benefits.

High-Dose Warfarin First-Trimester LMWH Regimen

For pregnant women requiring warfarin $> 5\,\text{mg/d}$, dose-adjusted LMWH at least 2 times per day during the first trimester, followed by warfarin during the second and third trimesters, is reasonable (COR 2a, LOE B-NR).

High-Dose Warfarin First-Trimester UFH Regimen

For pregnant women requiring warfarin $> 5\,\text{mg/d}$ when dose-adjusted LMWH is unavailable, dose-adjusted continuous IV UFH during the first trimester (aPTT $2\,\text{times control}$), followed by warfarin for the second and third trimesters, is reasonable (COR 2a, LOE B-NR).

Obstructive Left-Sided Mechanical Valve Thrombosis

For hemodynamically stable pregnant women with obstructive left-sided mechanical valve thrombosis, management with slow-infusion, low-dose fibrinolytic therapy is reasonable (COR 2a, LOE B-NR).

Aspirin Co-Administration in Pregnancy

For pregnant women with mechanical prostheses, aspirin $75\,\text{mg}$ to $100\,\text{mg}$ daily may be considered in addition to anticoagulation if needed for other indications (COR 2b, LOE B-NR).

LMWH Monitoring Harm Threshold

LMWH should not be administered to pregnant women with mechanical prostheses unless anti-Xa levels are monitored 4 to 6 hours after administration and dose is adjusted according to levels (COR 3: Harm, LOE B-NR).

Dabigatran in Mechanical Valve Prostheses

Anticoagulation with the direct thrombin inhibitor, dabigatran, should not be administered to patients with mechanical valve prostheses (COR 3: Harm, LOE B-R).

Anti-Xa Direct Oral Anticoagulants in Pregnancy

The use of anti-Xa direct oral anticoagulants with mechanical heart valves in pregnancy has not been assessed and is not recommended (COR 3: Harm, LOE C-EO).

Target Anti-Xa Level for LMWH

Target anti-Xa level of $0.8\,\text{U/mL}$ to $1.2\,\text{U/mL}$ measured 4 to 6 hours after dose, given at least 2 times per day with dose adjusted according to levels.

Target aPTT for Continuous UFH

Continuous intravenous UFH should be adjusted to an activated partial thromboplastin time (aPTT) $2\,\text{times control}$.

Anticoagulation for Prosthetic Mechanical Heart Valves in Women During Pregnancy Algorithm

A clinical decision flowchart detailing management pathways for pregnant women with mechanical heart valves, categorized by monitoring capability, warfarin dose thresholds ($\le 5\,\text{mg/d}$ vs $> 5\,\text{mg/d}$), LMWH/UFH choices, and delivery timelines.