Thromboembolism in pregnant women with mechanical prosthetic heart valves anticoagulated with low molecular weight heparin

Abstract

A 33 year old woman had undergone a mechanical prosthetic (Starr-Edwards) mitral valve replacement for valvular damage due to rheumatic heart disease, having had three spontaneous vaginal deliveries prior to her cardiac surgery. She conceived while on warfarin and was converted at six weeks of gestation to tinzaparin treatment dose (175 units/kg) by once daily subcutaneous injection; anti-Xa levels were not monitored. She presented at 26 weeks of gestation with a right-sided hemiplegia and dysphasia. A CT scan revealed a left parietal lobe infarct.She was treated initially with adjusted dose unfractionated heparin, maintaining activated partial thromboplastin time of 2.0 to 2.5 times the control. She was subsequently switched to warfarin and aspirin (150 mg/ d). She made a satisfactory recovery and continued on warfarin until 32 weeks of gestation when she was converted to another low molecular weight heparin, dalteparin, given by twice daily injection (100u/kg). Anti-Xa levels were in the therapeutic range at 0.9 u/ mL (0.4-1.0 u/mL). She was delivered of a healthy infant by uncomplicated elective caesarean section at 34 weeks and was warfarinised postnatally. Case report 2A 28 year old woman in her fourth pregnancy had undergone a mechanical prosthetic (Starr-Edwards) mitral valve replacement, also for valvular damage secondary to rheumatic fever as a child. Her past obstetric history included two early terminations of pregnancy and one emergency caesarean section for severe pre-eclampsia at 32 weeks of gestation in 1993. She was anticoagulated with warfarin during the latter pregnancy. Since her mitral valve replacement she had been poorly compliant on warfarin and had suffered a left temporoparietal infarct.She conceived while taking warfarin and was converted to tinzaparin (175 units/kg) at eight weeks of gestation, which was administered, as a once daily dose, under supervision on a daily outpatient basis. At 11 weeks of gestation she was found collapsed at home and on admission had a dense right-sided hemiparesis and aphasia. A CT scan showed an old left tempoparietal infarct with no new areas of haemorrhage and a clinical diagnosis of a thrombotic cerebrovascular accident was made. Her anti-Xa levels measured on admission were therapeutic. She was treated with intravenous unfractionated heparin, maintaining the activated partial thromboplastin time of 2.0 and 2.5 times the control, and then restarted on therapeutic doses of tinzaparin until 16 weeks of gestation when she was re-warfarinised.At 30 weeks of gestation she developed acute pulmonary ooedema secondary to fast atrial ®brillation and underwent an emergency caesarean section due to deterioration in her clinical state. Prior to this deterioration the International Normalised Ratio (INR) was maintained in the therapeutic range. There was no suggestion that the deterioration in the clinical state was due to thrombotic complications. Case report 3A 23 year old woman developed haemoptysis and shortness of breath during her ®rst pregnancy in 1995. She ...

Low molecular weight heparin (dalteparin) for the treatment of venous thromboembolism in pregnancy

“…One intrauterine death was observed in a high-risk pregnancy (habitual smoking, obesity, and gestational diabetes), but it is unlikely that this complication was related to dalteparin treatment. Our study is corroborated by several other reports, mostly case reports, on the effect of LMWH treatment for acute venous thromboembolism in pregnancy 13,21,22 . Lepercq et al 12 reported retrospective data on the treatment with enoxaparin in 49 women with acute venous thromboembolism in pregnancy, but this study does not provide any details on efficacy and safety and dose adjustments and achieved heparin concentrations.…”

Low-molecular-weight heparins for thromboprophylaxis and treatment of venous thromboembolism in pregnancy: a systematic review of safety and efficacy

“…From these, we excluded 11 studies of 43 patients with artificial heart valves 20,23,36,47,52,54,55,65,72,74,91 ; 1 case report of primary pulmonary hypertension 49 ; 2 studies of 18 pregnancies in 16 patients 83 and 4 pregnancies 86 reported elsewhere; and 3 studies for methodologic reasons because insufficient information regarding LMWH use was given. 64,81,94 In total, 64 studies reporting 2777 pregnancies were included in the analysis.…”

Successful Use of Danaparoid in Two Pregnant Women With Heart Valve Prosthesis and Heparin-Induced Thrombocytopenia Type II (HIT)

“…[12][13][14][15] For this reason, low molecular weight heparin throughout pregnancy in doses adjusted to keep a 4-hour postinjection anti-Xa heparin level at approximately 1.0 to 1.2 U/mL is recommended. 16 In both women described in our case report, plasma anti-Xa activity responses were well above the recommended target range of 0.6 to 1.0 U/mL, which might have facilitated the hematoma formation in case 2.…”