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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 17  |  Issue : 1  |  Page : 76-78

Anticoagulation in a pregnant patient with mechanical heart valves: Case reports and literature review


1 Department of Medicine, Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria
2 Department of Haematology, Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria

Date of Submission22-Jul-2019
Date of Decision13-Oct-2019
Date of Acceptance13-Dec-2019
Date of Web Publication30-Jun-2020

Correspondence Address:
Dr. M Z Usman
Department of Medicine, Usmanu Danfodiyo University Teaching Hospital, Sokoto
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njc.njc_18_19

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  Abstract 


Patients with prosthetic mechanical heart valves require a life-long anticoagulation. This is more so during pregnancy which increases the risk of thrombosis. We present two pregnant patients with prosthetic mechanical valves managed up to delivery. All the patients were on warfarin before conception which was changed to unfractionated heparin after confirmation of pregnancy. At 14 weeks gestation, they were changed back to warfarin until 36 weeks gestation. Unfractionated heparin was reintroduced until delivery. All the patients had minimal postpartum hemorrhage. Mrs. XX, one of them, had four successful deliveries since the placement of mechanical valve. Pregnancy for a woman mechanical valve poses a greater risk to both the mother and the fetus. This group of women should have preconception care in a specialized program.

Keywords: Anticoagulation, pregnancy, prosthetic mechanical valve


How to cite this article:
Isezuo S A, Umar H, Usman M Z, Ndakotsu M A. Anticoagulation in a pregnant patient with mechanical heart valves: Case reports and literature review. Nig J Cardiol 2020;17:76-8

How to cite this URL:
Isezuo S A, Umar H, Usman M Z, Ndakotsu M A. Anticoagulation in a pregnant patient with mechanical heart valves: Case reports and literature review. Nig J Cardiol [serial online] 2020 [cited 2020 Oct 28];17:76-8. Available from: https://www.nigjcardiol.org/text.asp?2020/17/1/76/288642




  Introduction Top


Patients with prosthetic mechanical heart valves should always be on prophylactic anticoagulation therapy for thromboembolic events.[1] As pregnancy represents a high-risk period for thrombosis, those with mechanical heart valves should be accorded greater importance. We present two pregnant patients with prosthetic mechanical mitral valves.


  Case Reports Top


Case 1

Mrs. K. H. presented first on August 8, 2000, with a year history of heart failure (dyspnea, orthopnea, paroxysmal nocturnal dyspnea, and body swelling) and she was diagnosed to have rheumatic heart disease (mitral stenosis).

She had mechanical mitral valve replacement (St. Jude's) in Saudi Arabia in 2005.

She was subsequently placed on tablets warfarin 5 mg with a good international normalized ratio (INR) since surgery. She was discovered to be pregnant (estimated gestational age [EGA] 5 weeks) in February 2012, where warfarin was replaced with subcutaneous unfractionated heparin 10,000 i.u. 12 hourly, which was later increased to 15,000 i.u 12 hourly 2 weeks after commencement of heparin. Warfarin 7.5 mg daily was later introduced at 14 weeks EGA, where heparin was stopped. This was continued till 36 weeks EGA where warfarin was stopped, and subcutaneous unfractionated heparin 12,500 i.u 12 hourly was introduced. She had planned induction of labor with infective endocarditis prophylaxis, and she delivered a 2.75 kg live female baby, with minimal postpartum hemorrhage (PPH). She had implanon inserted before discharge. The child was discovered to have sickle cell anaemia at the age of 3 months after presenting with features of dactylitis.

Case 2

Mrs. XX is a 42-year-old homemaker who had a history of acute rheumatic fever when she was 8 years old (fever, fleeting joint pains). She later presented to ABUTH with symptoms of heart failure when she was 22 years of age (1991) where she was diagnosed of rheumatic heart disease (mitral stenosis). She had mechanical mitral valve replacement (St. Jude's) in the United Kingdom in 1993. She was subsequently placed on tablets warfarin 5 mg with a good INR since surgery. She was discovered to be pregnant (EGA 2–3 months) in 2000, where warfarin was replaced with subcutaneous unfractionated heparin 10,000 i.u. 12 hourly. Warfarin 7.5 mg daily was later introduced at 14 weeks EGA, where heparin was stopped. This was continued till 36 weeks EGA where warfarin was stopped, and subcutaneous unfractionated heparin 12,500 i.u 12 hourly was introduced. She had a vacuum delivery with infective endocarditis prophylaxis. She had a male live baby with no abnormality. There was minimal PPH. She had no family planning despite counseling.

In 2003, Mrs. XX was discovered to be pregnant at 12 weeks EGA and warfarin was replaced with subcutaneous unfractionated heparin 10,000 i.u. 12 hourly. Warfarin 7.5 mg daily was later introduced at 14 weeks EGA, where heparin was stopped. This was continued till 36 weeks EGA where warfarin was stopped, and subcutaneous unfractionated heparin 12,500 i.u 12 hourly was introduced. She had a vacuum delivery with infective endocarditis prophylaxis. She had a male live baby with no abnormality. There was minimal PPH. She had no family planning despite counseling.

In 2007, Mrs. XX was discovered to be pregnant at about EGA 10 weeks. Warfarin 7.5 mg daily was later introduced at 14 weeks EGA, where heparin was stopped. This was continued till 36 weeks EGA where warfarin was stopped, and subcutaneous unfractionated heparin 12,500 i.u 12 hourly was introduced. She had a planned induction of labor with infective endocarditis prophylaxis. She had a female live baby, with minimal PPH. She had intrauterine contraceptive device inserted which was later removed on account of menorrhagia.

In 2010, Mrs. XX was discovered to be pregnant at about EGA 5 weeks. Warfarin 7.5 mg daily was later introduced at 14 weeks EGA, where heparin was stopped. This was continued till 36 weeks EGA where warfarin was stopped, and subcutaneous unfractionated heparin 12,500 i.u 12 hourly was introduced. She had a planned induction of labor delivery with infective endocarditis prophylaxis. She had a live male baby with no abnormality. There was minimal PPH. She was counseled for bilateral tubal ligation which she declined. Her last menstrual cycle was in June 2013.


  Discussion Top


Pregnancy for a woman with a prosthetic heart valve poses a risk for both the mother and the fetus and has been described as a double jeopardy situation.[2] There has been a progressive decline in the incidence of rheumatic heart disease in the Western countries compared to the developing countries because of the improvement of hygiene.[3] This disease occurs as sequel to rheumatic fever caused by Lancefield Group A Streptococcus as an upper airway infection. This can be in the form of valve stenosis or incompetence necessitating valve replacement as was done in our patients.

Although successful pregnancy is possible for women with prosthetic heart valve, there are potential complications, some of which can be fatal. It is recommended that this group of women should have preconception care in a specialized program for high-risk patient by a multidisciplinary team[3] as was done in Mrs. K. H and XX.

There are two types of prosthetic heart valve tissue valves and mechanical heart valve. Tissue heart valves are less thrombogenic and have a shorter life span with a risk of structural valve deterioration following pregnancy which will necessitate another replacement.[4] The mechanical valve is durable and risk of structural valve deterioration is low; however, the patient has to be on anticoagulation for life.[4]

Physiological changes of pregnancy makes blood highly thrombogenic as there is elevation in clotting factors I, VII, VIII, IX, X, and XII and increased platelet adhesiveness. There is decrease in fibrinolytic activity and protein S. These changes make valve thrombosis and venous thromboembolism significant.[3]

Opinions differ in anticoagulation option for women with mechanical heart valve, and there is no consensus[3] as each modality is associated with some risk for both mother and fetus. It is however crucial to explain the risk to the patient as was done in our patients.

The teratogenic and fetotoxic effects of warfarin and the risk of bleeding in the mother and fetus during labor and delivery must be balanced against the thromboembolic risk associated with use of heparin. A strategy that can be used for anticoagulation is the use of warfarin throughout the period of pregnancy. Monitoring of anticoagulation is using INR keeping values between 2.5 and 3.5.[5] This is associated with less valve thrombosis; however, it is associated with fetal embryopathy which carries a risk of about 6% because it crosses the placenta barrier.[5] This risk is low if the dose is ≤5 mg daily.[5] This regimen is associated with abortions and preterm births.

Unfractionated heparin subcutaneously or intravenously can be used as soon as pregnancy is diagnosed for anticoagulation and continued throughout pregnancy.[6] It does not cross the placenta membrane and does not cause fetal abnormalities. It however does not offer effective anticoagulation causing valve thrombosis, stroke, and death.[6] Its use is monitored using activated partial thromboplastin time keeping values two times above normal.[7] Although unfractionated heparin does not cross the placenta and does not harm the fetus, it must be given parenterally (usually by subcutaneous injection twice daily) and like warfarin can cause maternal hemorrhage and also can cause maternal osteoporosis and thrombocytopenia[8]

Oral warfarin can be used daily from conception until 6 weeks gestation and is substituted with unfractionated heparin until 13 weeks gestation when embryogenesis would have been completed.[9] This will reduce the fetal risk associated with use of warfarin as was done in our patients. The oral warfarin is restarted at 36 weeks gestation in preparation for delivery. Warfarin secondarily coagulates the fetus in utero and increases risk of hemorrhagic disease after delivery.[9]

Low molecular weight heparin can also be used because of its ease of use and superior bioavailability.[4] It is administered subcutaneously and monitoring is done by measuring anti-Xa levels weekly. This measurement is not readily done in our laboratories.

Pregnancy in women with mechanical heart valve is a high-risk one; hence, they should be seen more frequently in collaboration with the obstetricians and hematologists as was done above. Serial echocardiography may be particularly useful in a patient with prosthetic heart valve who is vulnerable to thrombosis during pregnancy to assess the function of the prosthetic valve and other native valves in addition to the routine investigations in pregnancy.[4]

Delivery should be planned. Vaginal delivery is the safest mode of delivery and cesarean section is done solely for obstetric reasons except in patients who used oral warfarin throughout pregnancy because of the risk of intracranial hemorrhage in the baby during vaginal delivery.[4]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Inanç MT, Doǧdu O, Kaya MG, Doǧan A. Prosthetic mechanic valve thrombosis in pregnant women: A report of two cases. Turk Kardiyol Dern Ars 2009;37:57-60.  Back to cited text no. 1
    
2.
Elkayam U, Singh H, Irani A, Akhter MW. Anticoagulation in pregnant women with prosthetic heart valves. J Cardiovasc Pharmacol Ther 2004;9:107-15.  Back to cited text no. 2
    
3.
Pibarot P, O'gara PT. Braunwald's heart disease - A text book of cardiovascular medicine. 11th edition Philadelphia, Elsevier; 2018. p. 3578.  Back to cited text no. 3
    
4.
Elkayam U, Bitar F. Valvular heart disease and pregnancy: Part II: Prosthetic valves. J Am Coll Cardiol 2005;46:403-10.  Back to cited text no. 4
    
5.
Vitale N, De Feo M, De Santo LS, Pollice A, Tedesco N, Cotrufo M. Dose-dependent fetal complications of warfarin in pregnant women with mechanical heart valves. J Am Coll Cardiol 1999;33:1637-41.  Back to cited text no. 5
    
6.
Sbarouni E, Oakley CM. Outcome of pregnancy in women with valve prostheses. Br Heart J 1994;71:196-201.  Back to cited text no. 6
    
7.
Bates SM, Greer IA, Hirsh J, Ginsberg JS. Use of antithrombotic agents during pregnancy: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004;126:627S-44S.  Back to cited text no. 7
    
8.
Ginsberg JS, Greer I, Hirsh J. Use of antithrombotic agents during pregnancy. Chest 2001;119:122S-31S.  Back to cited text no. 8
    
9.
Chan WS, Anand S, Ginsberg JS. Anticoagulation of pregnant women with mechanical heart valves: A systematic review of the literature. Arch Intern Med 2000;160:191-6.  Back to cited text no. 9
    




 

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