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Pregnancy With St. Jude Medical Mitral Valve Prosthesis

Birol Yamak, MD, Mustafa Emir, MD, Tulga A Ulus, MD, Ayen Aksöyek, MD, Zafer Ican, MD, S Fehmi Katirciolu, MD, Ouz Tademir, MD

Department of Cardiovascular Surgery Türkiye Yüksek htisas Hospital Ankara, Turkey

For reprint information contact: Tulga A Ulus, MD Tel: 90 532 522 1520 Fax: 90 312 229 0148 email: uluss{at}yahoo.com Nide Sokak 20/6, Ulus Apt., Dikmen, Ankara 06460, Turkey.

	Abstract

TOP Abstract Introduction Patients and Methods Results Discussion References

 
From 1986 to 1995, 513 young women of childbearing age (11 to 45 years) underwent mitral valve replacement with a bileaflet St. Jude Medical prosthesis. Twenty-one patients became pregnant within 3 years postoperatively. The mean age of these patients at the onset of pregnancy was 27 ± 8 years (range, 16 to 43 years). Follow-up was complete for all pregnant patients. Of 11 who continued to take warfarin during pregnancy, one had a premature delivery, 2 had spontaneous abortions, and 8 had therapeutic abortions. Five patients who ceased oral anticoagulant therapy had normal deliveries but 4 underwent reoperation for valve thrombosis postnatally, with concurrent left hemiplegia in one case. The other 5 patients adhered to an anticoagulation protocol for pregnancy; there were 3 normal deliveries, 1 premature birth, and 1 abortion. There is a high risk of thromboembolism in patients with mechanical heart valves whose anticoagulants are interrupted during pregnancy. We believe that careful supervision can reduce maternal morbidity and mortality.

	Introduction

TOP Abstract Introduction Patients and Methods Results Discussion References

 
As there is no need for oral anticoagulation after valve replacement with a bioprosthesis, this is a suitable choice for young women who desire pregnancy. ^{1 – 4} Use of mechanical valves in such patients is limited because of the increased risk of thrombosis and other valve-related complications as well as the teratogenic side effects of oral anticoagulants. It is widely accepted that oral anticoagulants are contraindicated during the first and third trimesters of pregnancy. ^{5 – 8} The goal of anticoagulant therapy is to protect against potentially fatal throm-boembolic events. ^{9 – 11} Ethically, when this therapy is indicated it must be advocated during pregnancy in spite of the side effects on the fetus. The choice of anticoagulant therapy during pregnancy is still controversial. ^{5 – 7 , 12 , 13} We describe our experience of 21 patients who became pregnant after mitral valve replacement with a mechanical valve prosthesis.

	Patients and Methods

TOP Abstract Introduction Patients and Methods Results Discussion References

 
Between 1986 and 1995, 513 women of childbearing age (between 11 and 45 years) underwent mitral valve replacement with a bileaflet St. Jude Medical heart valve prosthesis (St. Jude Medical, Inc., St. Paul, MN, USA) at the department of cardiovascular surgery of Türkiye Yüksek htisas Hospital. Following valve replacement surgery, warfarin therapy was started with a dose of 2.5 mg per day immediately after extubation, followed by dipyridamole 3 x 75 mg per day and aspirin 100 mg per day after removal of the chest tubes. This dosage of warfarin was prescribed regardless of the prothrombin time or international normalized ratio. Patients having any other type of cardiac valve prosthesis were excluded from this study.

Twenty-one patients became pregnant during the follow-up period. All pregnancies occurred within the first 3 years (mean, 17.5 ± 7.6 months) of the follow-up period. The mean age of the pregnant patients was 27 ± 8 years. Most (55%) were in New York Heart Association functional class III, 25% were in class IV, and 20% were in class II. The anticoagulant protocol during pregnancy specified withdrawal of oral anticoagulants until the 13th week of gestation and replacement with subcutaneous heparin to control the activated partial thromboplastin time at 1.5 times normal. After the 13th week, treatment reverted to warfarin until the end of the second trimester. During the third trimester, warfarin was again replaced with heparin.

	Results

TOP Abstract Introduction Patients and Methods Results Discussion References

 
Follow-up was complete for the 21 patients who became pregnant. Total follow-up was 105.7 patient-years, the mean was 5.1 years, and the range was 1.54 to 9.24 years. Five patients decided to cease oral anticoagulant therapy; 4 had no medical therapy and 1 took only 100 mg of aspirin per day. All 5 had normal deliveries but 4 underwent reoperation for mechanical valve thrombosis in the first and second postnatal months. One of these 4 suffered concurrent left hemiplegia. Eleven patients continued to take warfarin during their pregnancies; 1 had a premature delivery, 2 had spontaneous abortions, and 8 had thera-peutic abortions. None of these 11 patients developed a prosthetic-valve-related complication. Five patients were managed according to the anticoagulation protocol for pregnancy; 3 had normal deliveries, 1 gave birth pre-maturely, and 1 had a spontaneous abortion. No embolic or prosthetic-valve-related complications were encountered.

	Discussion

TOP Abstract Introduction Patients and Methods Results Discussion References

 
For the subset of young female patients desiring pregnancy, there is still no ideal valve prosthesis. ^{1 – 4 , 8} Although bioprostheses do not require long-term oral anticoagulant therapy, the degeneration rate is higher in this young age group and pregnancy may increase the rate of deterio-ration. ¹ Pregnancy is a hypercoagulable status, therefore patients with a mechanical heart valve prosthesis have a higher risk of thromboembolic events. ^{5 , 6 , 12 , 13} The risk of thromboembolism in patients with mechanical valves must be controlled by strict adherence to anticoagulation therapy. The use of oral anticoagulants during early pregnancy, near term, and at delivery has been reported to be associated with an increase in the incidence of fetal malformations, stillbirths, and neonatal deaths from hemorrhage. Bioprosthetic heart valves were used in our clinic between 1982 and 1986 for young female patients. After this period, we used mechanical heart valves because of the high rate of degeneration of bioprosthetic valves, especially in this age group.

Heparin, a macromolecular drug, does not cross the placental barrier and offers theoretical advantages over warfarin. In order to prevent abortions and possible teratogenic effects, it was suggested that heparin should be substituted for warfarin in favor of the fetus before the most vulnerable period, embryogenesis. ¹³ However, in a study by Sbarouni and Oakley, ¹⁴ warfarin treatment was found to be safe, effective, and not associated with embryopathy, whereas heparin treatment was associated with more thromboembolic events and bleeding com-plications. Sareli and colleagues ¹⁵ used warfarin without interruption during the first and second trimesters in 49 patients. In 23 of these, warfarin was replaced with heparin until the 36th week of gestation but the other patients reverted to warfarin because of premature onset of labor. There were no maternal thromboembolic complications or maternal mortality. Eighteen patients had a premature delivery, 6 had stillbirths, warfarin embryopathy was encountered in 2 babies, and another 2 died postnatally from intracranial hemorrhage.

One of the most important factors after valve replacement with a mechanical prosthesis is the patient's compliance with the anticoagulation protocol. In this study, in spite of being proscribed a protocol for the period of the pregnancy, 11 patients continued to take warfarin and 5 stopped taking all medications. Only 5 patients adhered to the protocol; heparin usage had no detrimental effects on prosthetic valve function and there were 3 normal deliveries. However, the 11 patients who continued to take warfarin did not develop valve-related complications but none had a full-term delivery.

Because of the risk of thromboembolism in patients with prosthetic valves whose anticoagulants are stopped or interrupted during pregnancy, a woman who is contem-plating pregnancy after insertion of a prosthetic cardiac valve should receive counseling from her surgeon before conception and possible fetal and maternal complications should be discussed. We believe that pregnancy may not increase maternal morbidity or mortality with careful follow-up of these patients, however, it may adversely affect the fetus.

	References

TOP Abstract Introduction Patients and Methods Results Discussion References

 

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8. Yamak B, Karagöz HY, Zorlutuna Y, Eralp A, Tademir O, Bayazit K. Low-dose anticoagulant management of patients with St. Jude Medical mechanical valve prothesis. Thorac Cardiovasc Surgeon 1993; 41 :38 –42.[Medline]

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Birol Yamak Tulga A Ulus S Fehmi Katirciolu Ouz Tademir Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Yamak, B. Articles by Tademir, O. Search for Related Content PubMed Articles by Yamak, B. Articles by Tademir, O.