Kerala Heart Journal -rajesh jose

Case report

Kerala Heart J  2016; 6(2):xx-xx. 
 

Prosthetic heart valve thrombosis in pregnancy


Rajesh Jose *, P.K.Varma**, Gautam Agarwal***


*Assistant Professor     ** Professor     *** Senior resident


Corresponding author

Dr Rajesh jose
Assistant Professor,

Department of Cardiovascular and Thoracic Surgery,

Amrita Institute of Medical Sciences, Kochi, Kerela

rajeshj21304@aims.amrita.edu



Abstract

 

Effective anticoagulation is critical in patients with prosthetic heart valve [PHV], but remains challenging in pregnancy because both oral anticoagulation and heparin are associated with important fetal and maternal risks. Herein we report a case of 23-year-old pregnant woman presented with PHV thrombosis during late second trimester and complicated by Immune mediated thrombocytopenia.She underwent Redo MVR [25mm CE Perimount Plus Pericardial Bioprosthetic valve] + LSCS. Peri operatively she was managed with Platelet transfusions/ Immunoglobulins/ Steroid pulse therapy and recovered well.

  

 

Keywords  : Prosthetic Valve Thrombosis, Anticoagulation for PHV in Pregnancy,  Surgical management for PHV thrombosis.

 

  

Case report

 

A 23 year old Primi Gravida,  27 weeks of gestation, known  case of Rheumatic heart disease- Severe MR,  Mitral valve replacement done[Star Edward Prosthesis] 12 years ago. Now presented with DOE class III and echocardiogram showed Prosthetic valve dysfunction with Moderate PAH . She was diagnosed to have Immune thrombocytopenia [Platelet count 21000]  Oral  anticoagulation agents were stopped and she was treated with Heparin.

On heart team  meeting it was decided to observe the patient in ICU considering the symptomatic improvement as well as  her very low Platelet count. She received pulse IV Methyl Prednisolone , Revolade and IVIG to increase the platelet count. On suspicion of HIT she was continued on Fondaparine. After considering the Obstetric and neonatologist opinion we decided to continue with pregnancy as far as possible and to consider preterm  termination if patient become unstable.

At 30th week of gestation Fetal scan showed weight 933mg, good viability and platelet count went up to 70,000, hence decision was taken for elective LSCS along with Redo MVR.

 

She underwent Redo MVR [ 25mm CE Perimount Plus Pericardial Bioprosthetic valve(figure.1)] + LSCS. Peri operatively she was managed with Platelet transfusions/ Immunoglobulins/ Steroid pulse therapy. Within a week of surgery her Platelet counts reached normal values and she had an uneventful postoperative recovery and was discharged. After 2 months of care in neonatal ICU child gained 3 kg and discharged.



 

 

 

     

DISCUSSION

 

Pregnancy is associated with an increased risk of valve thrombosis in patients with mechanical prosthetic valve (MPV). Warfarin treatment is the best regimen against thromboembolic complications, but its use in the first trimester can result in embryopathy. Low molecular weight heparin (LMWH) does not cause embryopathy. However, the pharmacokinetics of LMWHs change during pregnancy and serial monitoring of anti-Xa levels is strongly recommended. In the absence of anti-Xa monitoring, treatment with a fixed dose of LMWH, may results in ineffective anticoagulation [2].

 

Rowan et al [3] reported the largest experience (n = 14 pregnancies) of pregnant women with mechanical heart valves treated with LMWH.  Their rate of valve thrombosis was 7%. Oran et al 6 reviewed the existing research and found 81 reported pregnancies in 75 women with mechanical heart valves treated with LMWH during pregnancy. In that review, the rate of valve thrombosis was 8.6%, and any thromboembolic complications occurred in 12.3% of pregnancies. However, in the review by Oran et al [4] LMWH doses varied, as did the method of monitoring, and this may provide an  explanation for differing rates of thromboembolic complications. In the series reported by Rowan et al, the rates of maternal thromboembolic events were relatively low compared to rates reported in older series using unfractionated heparin, in which rates were reported as high as 25%. However, similar to the limitations mentioned earlier with LMWH, direct comparisons of event rates are difficult because doses of unfractionated heparin used have varied considerably, and there are differences in the thrombogenicity of the mechanical valves in different series (i.e., higher rates of thrombosis with ball-and-cage valves). 7 In a meta-analysis by Chan et al[5] 7women treated with warfarin throughout pregnancy had lower incidence of thromboembolic complications and maternal death (3.9% and 1.8%, respectively) compared to regimens that included heparin treatment. Although treatment with warfarin may still be considered the ideal therapy to protect from thromboembolism, many women are reluctant to use warfarin during pregnancy because of potential fetal effects.

In the review by Oran et al, all 10 women with thromboembolic complications had mechanical mitral valves. Some experts have suggested that high-risk patients (women with first-generation mechanical valve in the mitral position) should not be treated by LMWH throughout gestation. Significant changes in gradients should alert physicians to the possibility of valve thrombosis, even when no thrombosis is seen, and patients should be hospitalized and anticoagulation therapy should be re evaluated or changed.

Oran et al also found that most cases of thromboembolic events occurred in women with inadequate dosing, lack of monitoring, or subtherapeutic anti-Xa levels. In 51 pregnancies in which anti-Xa levels were monitored and in adequate range (peak level >1 U/ml), only 1 patient was reported to have a thromboembolic complication. Similarly, Abildgaard et al [6] recently reported on 12 pregnancies with mechanical heart valves treated with LMWH, in which thromboembolism occurred in 2 women. However, these women with valve thromboembolism had received subtherapeutic doses of LMWH. The pharmacokinetics of LMWH have been shown to be altered during pregnancy. The clearance and the volume of distribution of LMWH are higher during pregnancy, and consequently, the plasma concentration is significantly lower. 1Therefore, the administration of LMWH on the basis of weight alone is inadequate, and measurement of anti-Xa levels is necessary to ensure effective anticoagulation. The American College of Chest Physicians recommends that LMWH doses be adjusted to achieve a peak anti-Xa level (4 hours after injection) of about 1 U/ml [7]. Barbour et al [8] showed that monitoring LMWH treatment by measuring only peak anti-Xa levels may be inadequate, because peak levels of 0.75 to 1 U/ml were associated with subtherapeutic trough levels of <0.5 U/ml in most cases. These data led some experts to recommend monitoring predose levels that should be maintained at the upper therapeutic range of 0.6 to 0.7 U/ml. The benefit of monitoring predose and 4-hour postdose anti-Xa levels in pregnant women with mechanical heart valves treated with LMWH is still uncertain.

References

[1] Schwartzenberg S, Perlman S, Levy R, Elkayam U, Goland S - J. Heart Valve Dis. - July 1, 2013; 22 (4); 603-6

[2] Taner Ulus, Utku Senol, Alparslan Birdane and Yuksel Cavusoglu,  PP-171 The Use of Low Molecular Weight Heparin During Pregnancy in Patients with Mechanical Heart Valves Carries Potential Risk for Valve Thrombosis: A Report of Three Cases,  American Journal of Cardiology, The, 2015-03-16, Volume 115, Pages S172-S172

[3] Rowan J.A., McCowan L.M., Raudkivi P.J., and North R.A.: Enoxaparin treatment in women with mechanical heart valves during pregnancy. Am J Obstet Gynecol 2001; 185: pp. 633-637

[4] Oran B., Lee-Parritz A., and Ansell J.: Low molecular weight heparin for the prophylaxis of thromboembolism in women with prosthetic mechanical heart valves during pregnancy. Thromb Haemost 2004; 92: pp. 747-751\

[5] Chan W.S., Anand S., and Ginsberg J.S.: Anticoagulation of pregnant women with mechanical heart valves: a systematic review of the literature. Arch Intern Med 2000; 160: pp. 191-196

[6] Abildgaard U., Sandset P.M., Hammerstrom J., Gjestvang F.T., and Tveit A.: Management of pregnant women with mechanical heart valve prosthesis: thromboprophylaxis with low molecular weight heparin. Thromb Res 2009; 124: pp. 262-267

[7] Bates S.M., Greer I.A., Hirsh J., and Ginsberg J.S.: Use of antithrombotic agents during pregnancy: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126: pp. 627S-644S

[8] Barbour L.A., Oja J.L., and Schultz L.K.: A prospective trial that demonstrates that dalteparin requirements increase in pregnancy to maintain therapeutic levels of anticoagulation. Am J Obstet Gynecol 2004; 191: pp. 1024-1029

 

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