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Ann Thorac Surg 1998;65:1512
© 1998 The Society of Thoracic Surgeons

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Correspondence

Reply

^a Department of Surgery, University Hospital, PO Box 30001, 9700 RB Groningen, the Netherlands

We thank Dr Cheng for his comments on our article [1] and appreciate the opportunity you have offered us to comment on his letter to your journal.

As to the correlation between pregnancy and the concomitant occurrence of an aortic dissection, various physiologic changes during pregnancy may encourage the development of this catastrophic event. Hormonal changes may be important in weakening the aortic wall, especially in the last trimester of pregnancy, inducing alterations resembling medial degeneration [2]. However, as stated in our article [1], signs of medial degeneration could only be detected in two aortic specimens, suggesting that other factors also play a role. Among them are mechanical forces acting on the aortic wall. It was generally thought that hemodynamic stress occurs mainly in the third trimester and in the puerperium; when blood volume, cardiac output, stroke volume, and blood pressure all increase. However, recent investigation has demonstrated that hemodynamic stress is at a maximal level during the second trimester and labor [3], possibly resulting in a weakened aorta thereafter. In addition, external compression of the abdominal aorta by the pregnant uterus may lead to undue hemodynamic stress on the heart and arteries proximal to the site of compression and may contribute to the stretching of a weakened thoracic aorta [2].

Concerning the use of ß-blockers during pregnancy, Dr Cheng elucidates that they should be used in the lowest possible dose and should be avoided before labor [4]. However, we would like to stress once again that the saving of both mother’s and child’s lives is at stake here. From a maternal point of view, ß-blockers (eg, propranolol, labetolol, esmalol) are used to decrease the force of ventricular contraction and to lower systemic blood pressure. They are used to prevent dissection and to control dissection already occurring. On the other hand, it seems in the best interests of the child not to use high-dose ß-blockers [4], but in comparison with other antihypertensive drugs (which all pass the placental barrier), they seem to induce less effects on the fetus’ circulation [5, 6]. We suggest to titrate exactly that dose of ß-blocking drugs that is necessary to achieve a normal blood pressure in the mother (preferably < 140/90 mm Hg in the third trimester). The dose should be tailored to the needs of each individual patient.

Finally, as the medical treatment of aortic dissection during pregnancy usually occurs during the third trimester, the possible teratogenic effects of propranolol are probably of less importance.

References

1. Zeebregts C.J., Schepens M.A., Hameeteman T.M., Morshuis W.J., Brutel de la Rivière A. Acute aortic dissection complicating pregnancy. Ann Thorac Surg 1997;64:1345-1348.[Abstract/Free Full Text]
2. Rutherford R.B., Nolte J.E. Aortic and other arterial dissections associated with pregnancy. Semin Vasc Surg 1995;8:299-305.[Medline]
3. Duvekot J.J., Peeters L.L.H. Maternal cardiovascular hemodynamic adaptation to pregnancy. Obstet Gynecol Surv 1994;49(Suppl):S1-S14.[Medline]
4. Cheng T.O. Caution in use of beta blockers during pregnancy. Cathet Cardiovasc Diagn 1995;34:186.
5. Lindheimer M.D. Hypertension in pregnancy. Hypertension 1993;22:127-137.[Abstract/Free Full Text]
6. Broughton Pipkin F. The hypertensive disorders of pregnancy. Br Med J 1995;311:609-613.[Abstract/Free Full Text]

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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Marc A. Schepens Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zeebregts, C. J.A.M. Articles by Schepens, M. A. Search for Related Content PubMed PubMed Citation Articles by Zeebregts, C. J.A.M. Articles by Schepens, M. A.