132 Obstetrics and Gynecology Board Review •••
❍ Are porcine or mechanical valves preferred in pregnancy?
Porcine valves are safer because they do not require anticoagulation.
❍ What is the maternal mortality rate for women with mechanical valves?
3% to 4%, largely due to thromboembolic events and hemorrhage.
❍ What are the risks and benefits of using warfarin for anticoagulation in pregnancy?
Warfarin is teratogenic, causing fetal malformations 6% of the time. Warfarin also may cause stillbirth (7%) and
miscarriage (32%). However, it is the most effective method of anticoagulation for women with mechanical heart
valves.
❍ What anticoagulation regimen is recommended for women with mechanical valves in pregnancy?
Twice daily low molecular weight heparin (LMWH), twice daily unfractionated heparin (UFH), or if high risk of
thromboembolism, LMWH/UFH until >13 weeks’ gestation, then warfarin until close to delivery when heparin
is resumed.
❍ What complication of mitral stenosis occurs in pregnancy?
Heart failure due to volume overload from increased preload and cardiac output in pregnancy.
❍ Why must tachycardia be avoided in patients with mitral stenosis?
Tachycardia shortens ventricular filling time, which is critical to maintain adequate stroke volume in patients with
mitral stenosis. Thus, tachycardia can lead to pulmonary edema and should be treated with beta blockade.
❍ Does mitral regurgitation typically improve or worsen during pregnancy, and why?
Mitral regurgitation tends to improve in pregnancy because decreased systemic vascular resistance leads to less
regurgitation.
❍ What is the safest form of analgesia in labor for women with severe aortic stenosis?
Narcotic analgesia is safer than epidural analgesia because of possible hypotension associated with epidural
analgesia. Women with aortic stenosis require end-diastolic ventricular filling pressures to be maintained in order
to maintain systemic perfusion.
❍ What is the most common heart condition seen in pregnancy?
Congenital heart disease.
❍ What is the most concerning complication of a patent foramen ovale in pregnancy?
Paradoxical embolism—passage of a venous clot through the patent foramen ovale into the systemic circulation
❍ What is the maternal mortality rate for women with Eisenmenger syndrome?
30% to 50%, therefore pregnancy is not recommended.
❍ For women with unrepaired ventricular septal defects (VSDs), what is recommended?
Antibiotic prophylaxis for bacterial endocarditis.