title: Use of high intensity adjusted dose low molecular weight heparin in women with mechanical heart valves during pregnancy: a single-center experience.
abstract: The use of standard dose low molecular weight heparin (LMWH) to anticoagulate women with mechanical valves in pregnancy is associated with morbidity and mortality. We conducted a prospective audit of the use of adjusted dose high intensity LMWH in 12 pregnancies in 11 women with prosthetic heart valves. LMWH +/- low-dose aspirin was started at therapeutic-dose with monitoring of anti-Xa levels to achieve a target level of 1.0-1.2 IU/mL (0.8-1.2 in the first 3/12 pregnancies). This necessitated a mean increase in the dose of LMWH of 54.4% (SD+/-33.2) over initial dose. Eleven of 12 pregnancies resulted in live births, with one intrauterine fetal death at 37 weeks. One non-fatal valve thrombosis occurred at 26 weeks gestation associated with subtherapeutic anti-Xa levels. Three patients experienced major bleeding. This regime provides a therapeutic option for women with mechanical heart valves during pregnancy, provided anti-Xa levels are kept within the target range. These patients require close surveillance for bleeding and thrombotic complications within a multi-disciplinary setting.
authors.affiliation: Department of Hematology, University College London and University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: John
authors.initials: J
authors.lastname: Quinn
authors.forename: Kate
authors.initials: K
authors.lastname: Von Klemperer
authors.forename: Ruth
authors.initials: R
authors.lastname: Brooks
authors.forename: Donald
authors.initials: D
authors.lastname: Peebles
authors.forename: Fiona
authors.initials: F
authors.lastname: Walker
authors.forename: Hannah
authors.initials: H
authors.lastname: Cohen
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects; D001241:Aspirin / Q000008:administration & dosage; D065427:Factor Xa Inhibitors; D005260:Female; D006350:Heart Valve Prosthesis; D006470:Hemorrhage / Q000139:chemically induced; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage* / Q000009:adverse effects; D006801:Humans; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000188:drug therapy / Q000517:prevention & control; D011256:Pregnancy Outcome; D011446:Prospective Studies
chemical_list: D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D006495:Heparin, Low-Molecular-Weight; D001241:Aspirin