LETTERS TO THE EDITOR
Reply
Nicola Vitale, MD, PhDa,
Marisa De Feo, MD and
Maurizio Cotrufo, MD, FESCTS
a Department of Cardiac Surgery, Monaldi Hospital, Second Unviersity of Naples, Via Vincenzo Migliaro 27, 80128 Naples, Italy
Nicola.Vitale{at}excite.co.uk
We read with great interest the letter by Nelson-Piercy et al. regarding our article (1). They gave us the benefit of their experience.
We appreciate the points raised by them—that is, their concern about the discontinuation of warfarin only two days before cesarean section and the consequent hemorrhagic risks for the fetus.
Pregnancy increases the risk of valve thrombosis (2); therefore, we had two main concerns at the time we devised our policy for pregnant women with mechanical valves: 1) protecting the mother from valve thrombosis; and 2) reducing the risk of fetal complications as much as possible.
Undoubtedly, warfarin is considered to be the best anticoagulant agent for patients with mechanical valves (3). Even though intravenous heparin has been used in the management of pregnant women, the thromboembolic risk was found to be four to five times higher for women taking heparin than for those taking an oral anticoagulant agent (4). In our experience, in a general population, we have observed a higher rate of thromboembolic and thrombotic complications in patients with first- and second-generation mechanical valves as compared with bileaflet valves (5). Because 34 of 43 patients in our series had caged-ball or tilting disc valves, mostly in the mitral position, we opted for the anticoagulation management that enabled us to minimize the thrombotic risk during the entire gestation period.
We agree that warfarin is still present in the fetus at the time of cesarean section, but no hemorrhagic complications have been observed in our series. Unfortunately, the International Normalized Ratio (INR) levels in the babies were unknown, and therefore it was difficult to assess the extent of anticoagulation in the fetus. Ideally, the fetal INR should be checked soon after birth.
With respect to the authors’ concern for the fetus during programmed cesarean section, we have not observed any untoward effect of this procedure on the babies. Moreover, no deep vein thromboses were observed in our patients, despite the high risk pointed out by the authors.
Finally, with respect to their recommendation to use heparin at 36 weeks in preparation for induction of labor or cesarean section at 38 weeks, we consider this policy applicable in selected patients. We consider warfarin a better anticoagulant agent for patients with first- and second-generation mechanical valves in the mitral position. Therefore, we do not know whether heparin will yield results as satisfactory as those with warfarin in reducing the thrombotic risk in this subset of patients. In contrast, patients with bileaflet valves may be managed with intravenous heparin during their last two weeks of gestation, keeping in mind the side effects of heparin (6) and the prolonged hospital stay.
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References
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1. 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;33:1637–1641[Abstract/Free Full Text]
2. Bonnar J. Haemostasis and coagulation disorders in pregnancy. Bloom AL, Thomas DP. Haemostasis and Thrombosis. London: Churchill Livingstone; 1994. p. 570–583
3. Routledge PA, Shetry HGM. Pharmacology of anticoagulants. Butchart EG, Bodnar E. Thrombosis, Embolism and Bleeding. London: ICR Publishers; 1992. p. 263–276
4. Hanania G, Thomas D, Michel PL, et al. Pregnancy and prosthetic heart valves: a French cooperative retrospective study of 155 cases. Eur Heart J. 1994;15:1651–1658[Abstract/Free Full Text]
5. Renzulli A, de Luca L, Caruso A, Verde R, Galzerano D, Cotrufo M. Acute thrombosis of prosthetic valves: a multivariate analysis of the risk factors for a life threatening event. Eur J Cardiothorac Surg. 1993;1:412–421
6. Oakley CM. Anticoagulants in pregnancy. Br Heart J. 1995;74:107–111[Free Full Text]
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