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eComment. Re: Mechanical prosthetic mitral valve thrombosis in a first trimester pregnant woman
eComment. Are LWMH effective in mechanical valve prosthesis anticoagulation during pregnancy?
eComment. Cardiac operation during pregnancy: What is the appropriate management?
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Leo A. Bockeria Bakoulev Scientific Center for Cardiovascular Surgery , Roublevskoye Sh. 135, 121552 Russia, Olga L. Bockeria, Irina A. Goustova, Anna S. Mordvinova.
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leoan{at}heart-house.ru Leo A. Bockeria, et al.
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Interactive CardioVascular and Thoracic Surgery 2009, doi:10.1510/icvts.2009.220806C © 2009 European Association of Cardio-Thoracic Surgery Pregnancy in women with mechanical prosthesic valves is associated with a high risk of maternal mortality as the outcome of prosthetic-valve thrombosis. One of the actual goals of modern cardiology is an adequate anticoagulation therapy for such category of patients. It’s well known that clinical recommendations concerning valvular heart disease during pregnancy are dependant on the period of gestation. In this report [1], Carnero-Alcazar M. and colleagues describe their experience of the mitral valve replacement due to mechanical prosthetic valve thrombosis which occurred during first trimester of pregnancy. The cardiopulmonary bypass has many potential adverse effects that can compromise uteroplacental perfusion and fetal development. The authors have performed the surgical procedure using high perfusion pressure and mild hypothermia during cardiopulmonary bypass. The maintenance of acidbase balance during open heart, the use of high flow rate, high perfusion pressure and normothermia or mild hypothermia during cardiopulmonary bypass, minimization of the duration of the aortic cross-clamp time has a significant importance in successful outcomes of operation. Administration of warfarin during pregnancy in women with mechanical valves [2] diminishes the risk of development of prosthetic valve thrombosis. But it is associated with a high level of fetal loss (approximately 30 percent including spontaneous abortions, stillbirths, and neonatal deaths). The rate of adverse events during warfarin therapy is considered to be 6%. Administration of warfarin is associated with “fetal warfarin syndrome” characterized by nasal hypoplasia, stippled epiphyses, limb deformities, and respiratory distress. Warfarin therapy in period between 6 and 12 weeks of gestation doubles in fetal mortality compared to administration of heparin. Injection of heparin during the first trimester reduces by half the risk of maternal thromboembolism and death (9.2% and 4.2%, respectively) [3]. Nevertheless, long-term heparin administration is associated with a higher risk of heparin-induced thrombocytopenia and osteopenia in women [1]. A strategy of substituting warfarin for low molecular weight heparin during the period of organogenesis (6–12 weeks of gestation) reduces the risk of warfarin embryopathy but increases twice the maternal thromboembolism (9%). In the Bakoulev Center for Cardiovascular Surgery, the management of pregnant women with mechanical valves has been investigated. Only preliminary data have been accumulated. According to the data presented in overviews and case reports, usually the caesarian section is applied in most of the cases before radical correction of cardiac pathology. Based on cite data it is recommended to administer warfarin with target level of INR 2,0-3,0. It’s inadmissible to use warfarin therapy during two periods: between 6 and 12 weeks of pregnancy and after 36 weeks of pregnancy [2]. Within these periods an unfractionated heparin should be applicated under monitoring of coagulation. In spite of the existence of well-tested cardiopulmonary bypass protocol, complications are still observed. The problem is insufficiently known because of limited quantity of studies. Further investigation should be carried out. References [1] Carnero-Alcazar M, Reguillo-Lacruz F, Montes-Villalobos L, Rodriguez-Hernandez JE. Mechanical prosthetic mitral valve thrombosis in a first trimester pregnant woman. Interact CardioVasc Thorac Surg, doi:10.1510/icvts.2009.220806. [2] Bockeria L.A., Bockeria O.L, Orjonikidze N.V., Lobacheva G.V., Bespalova E.D., Nechai Y.A., Volkovskaya I.V., Trofimova E.R., Mordvinova A.S. The management and delivery in pregnant women with severe cardiovascular pathology. The Bulletin of Bakoulev Center for Cardiovasc Surg. 2009. [3] Ginsberg JS, Greer I, Hirsh J. Use of antithrombotic agents during pregnancy. Chest 2001;119:Suppl:122S-131S. |
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Yolanda Carrascal University Hospital Valladolid, Ramón y Cajal 3, 47005 Valladolid, Spain
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ycarrascal{at}hotmail.com Yolanda Carrascal
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Interactive CardioVascular and Thoracic Surgery 2009, doi:10.1510/icvts.2009.220806B © 2009 European Association of Cardio-Thoracic Surgery I have read with interest the case reported by Carnero-Alcazar et al in which referred to surgical treatment of mitral valve thrombosis in a pregnant patient [1]. In reference to the presented case, I would like to comment that this report adds to others referring low weight molecular heparin (LWMH) inefficiency to prevent thrombosis of mechanical valve prosthesis during pregnancy [2]. Although the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition) [3] include its use as a type IC recommendation, in order to anticoagulate mechanical valve prosthesis in pregnant patients, it seems necessary to evaluate its harmlessness with caution. Up to now, aetiology of mechanical valve thrombosis is related to low therapeutic levels of LWMH motivated by increasing of plasmatic volume distribution during pregnancy. In consequence, monitoring levels of anti Xa was considered adequate in order to evaluate its therapeutic efficiency [3]. Thrombotic events described up to date, were associated with decreasing of anti Xa levels below the recommended by LMWH manufacturers (0.6-1.2 U/ml). The difficulty in determining efficacy of LMWH usage in these cases is due to absence of prospective studies. Recently, Yinon et al [4] have reported, in a prospective study (including 23 patients with aortic or mitral mechanical valve prosthesis, under LWMH treatment throughout their pregnancies, with 4-hour post-injection anti-Xa levels of 1 to 1.2 IU/ml and associated with daily administration of 81 mg. of aspirin), the appearance of a thrombosis in a second generation mechanical aortic valve prosthesis, as the patient who illustrates the case presented by Carnero- Alcazar et al [1]. Neither of the patients could be classified, according to the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines criteria, as high risk thrombosis patients. In conclusion, both cases suggest that safety of isolated anti Xa monitoring cannot be adequate to prevent thrombotic events in pregnant patients with mechanical valve prosthesis. Complementary clinical and echocardiographic periodic controls and evaluation of efficacy of monitoring pre dose of anti Xa [5] seem to be necessary to prevent this type of event. References [1] Carnero-Alcazar M, Reguillo-Lacruz F, Montes-Villalobos L, Rodríguez-Hernández JE. Mechanical prosthetic mitral valve thrombosis in a first trimester pregnant woman. Interact CardioVasc Thorac Surg doi:10.1510/icvts.2009.220806. [2] Roberts N, Ross D, Flint SK, Arya R, Blott M. Thromboembolism in pregnant women with mechanical prosthetic heart valves anticoagulated with low molecular weight heparin. Br J Obstet Gynaecol 2001; 108:327–329 [3] Bates SM, Greer IA, Pabinger I, Sofaer S, Hirsh J. Venous thromboembolism. Thrombophilia, antithrombotic therapy, and pregnancy: American College of Chest Physicians Evidence Based Clinical Practice Guidelines, 8th edition. Chest 2008; 133: 844S–886S. [4] Yinon Y, Siu SC, Warshafsky C, Maxwell C, McLeod A, Colman JM, Sermer M, Silversides CK. Use of low molecular weight Heparin in pregnant women with mechanical heart valves. Am J Cardiol 2009; 104: 1259-63. [5] Elkayam U, Bitar F. Valvular heart disease and pregnancy: part II: prosthetic valves. J Am Coll Cardiol 2005; 46: 403– 410. |
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Rafet Gunay Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center, Istanbul, Turkey
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rafetgunay{at}hotmail.com Rafet Gunay
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Interactive CardioVascular and Thoracic Surgery 2009, doi:10.1510/icvts.2009.220806A © 2009 European Association of Cardio-Thoracic Surgery We read with great interest the report by Carnero-Alcazar and coworkers regarding the successful mechanical mitral valve replacement due to prosthetic valve thrombosis in a first trimester pregnant woman [1]. Two percent of all pregnant women suffer from some kind of cardiac pathology. Although this incidence varies in different countries, cardiac disease is the leading cause of death in pregnancy [2]. Many factors are associated with pregnancy in cardiopathic patient such as social, ethical and maternal desire for decision whether the pregnancy will be terminated or maintained. When a cardiac problem requires an operation during pregnancy the risks are inevitably increased and substantial efforts must be made to reduce the risk. There are several cases reported in the literature of CPB used on pregnant women at various stages of pregnancy [2,3,4]. Many factors associated with cardiac operations requiring cardiopulmonary bypass can adversely affect both the mother and the fetus, but the embryo-fetal mortality is found that highly increased under hypothermic conditions than the normothermic conditions although maternal mortality did not differ at different temperatures [2]. Younger gestational age and a greater degree of hypothermia are known to increase fetal morbidity during CPB [3]. Cardiophatic pregnant patients can be separated into two groups. One of them is pregnant women who have cardiac pathologies and the other is pregnant women who require emergent surgical interventions. The cardiopathic patient, even if well compensated, can easily sustain acute heart failure caused by the increase of cardiorespiratory requirements during pregnancy. Ideally, valve disease should be evaluated before pregnancy and treated if necessary. However, pregnancy is often already present when the patient presents. In such cases, if possible, it is always preferable to delay surgery until the time the fetus is viable and a caesarean section can be performed as part of a concomitant procedure [4]. On the other hand, medical therapy is not always sufficient to drive a heart with a reduced functional reserve and acute complications, such as the thrombosis of a valvular prosthesis, endocarditis or acute aortic dissection, which can seriously compromise the heart functions of the pregnant woman. When the open heart operation is necessary to save the patient's life in such situations, the fetus could be seriously compromised after exposure to cardiopulmonary bypass. High-flow, high-pressure, normothermic bypass offers the least risk to the fetus. Fetal heart and uterine monitoring is essential to allow adjustments to the flow to ensure adequate placental perfusion and early control of contractions as they are associated with significant fetal loss [4]. Pregnancy is associated with a hypercoagulable state due to relative decreases in protein S activity, stasis, and venous hypertension and predisposition to dissection with or without an underlying connective tissue disorder due to decrease in collagen synthesis. Hence, the appropriate anticoagulation management is important in pregnancy. Fetal mortality due to operation is considerably less than 100% mortality incurred by therapeutic abortion. This case report has shown once again that open heart operation is not a contraindication to pregnancy prolongation and it has been reported to be undertaken at any gestational age but it should be kept in mind that is best between 24 and 28 weeks’ gestation, after the completion of organogenesis. Pump flow and mean arterial pressure during cardiopulmonary bypass seem to be the most important parameters that influence fetal oxygenation. References [1] Carnero-Alcazar M, Reguillo-Lacruz F, Montes-Villalobos L, Rodriguez-Hernandez JE. Mechanical prosthetic mitral valve thrombosis in a first trimester pregnant woman. Interact CardioVasc Thorac Surg doi:10.1510/icvts.2009.220806 [2] Pomini F, Mercogliano D, Cavalletti C, Caruso A, Pomini P. Cardiopulmonary bypass in pregnancy. Ann Thorac Surg 1996; 61: 259-68. [3]Mahli A, Izdes S, Coskun D. Cardiac Operations during pregnancy: Review of factors influencing fetal outcome. Ann Thorac Surg 2000; 69: 1622-6. [4]Parry AJ, Westaby S. Cardiopulmonary bypass during pregnancy. Ann Thorac Surg 1996; 61: 1865-1869 |
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