Ann Thorac Surg 1998;66:268-270
© 1998 The Society of Thoracic Surgeons
Case Reports
Cardiopulmonary bypass in a gravid patient: perioperative changes in endothelin levels
James L. Zellner, MDa,
Scott B. Kribbs, BSa,
B. Hugh Dorman, MD, PhDa,
Francis G. Spinale, MD, PhDa
a Departments of Surgery and Anesthesiology, Medical University of South Carolina, Charleston, South Carolina, USA
Accepted for publication February 10, 1998.
Address reprint requests to Dr Spinale, Cardiothoracic Surgery, Rm 418 CSB, Medical University of South Carolina, 171 Ashley Ave, Charleston, SC 29425
 |
Abstract
|
|---|
Transient elevations of the potent vasoconstrictive peptide endothelin have been reported to occur with the institution of cardiopulmonary bypass. We measured plasma endothelin levels in a 24-year-old gravid patient undergoing a mitral valve replacement operation. Plasma endothelin levels increased by more than 250% in the first 24 hours postoperatively and remained elevated above baseline values at 36 hours postoperatively.
|
Introduction
|
|---|
Pregnant patients with preexisting cardiovascular disease may require a cardiac operation and the institution of cardiopulmonary bypass (CPB). Past clinical studies have reported that CPB during pregnancy may be associated with fetal loss in the early postoperative period [1]. Furthermore, the relative incidence of fetal loss (ie, spontaneous abortion) has been reported to be higher in gravid patients undergoing mitral valve replacement [1]. Although the fundamental contributory mechanism(s) responsible for spontaneous abortion remain unclear, decreased placental blood flow with subsequent placental ischemia has been implicated in this process [2, 3]. Past in vitro studies have demonstrated the potent vasoconstrictive effects of the peptide endothelin (ET) on the human fetal-placental circulation [4]. Moreover, past reports have demonstrated elevated ET levels during, and after, the institution of CPB [5]. However, the temporal changes in plasma ET levels that occur in the gravid patient with the induction of CPB and in the following perioperative period remain unknown. Accordingly, we serially measured plasma ET levels before, during, and after a mitral valve replacement operation in a gravid patient.
A 24-year-old woman (gravida IV, para I, abortion II) in the third month of pregnancy was admitted with a 4-day history of shortness of breath and hemoptysis. The patient’s medical history was significant for rheumatic heart disease with subsequent mitral valve replacement (St. Jude 31 mm) 15 years earlier. The patient denied any history of hypertension or renal disease. The patient further denied any alcohol, tobacco, or narcotic use. Fetal ultrasound was performed, demonstrating a viable fetus. Echocardiography demonstrated compromised valve leaflet movement; therefore, emergent mitral valve replacement was proposed.
Informed consent was obtained for the operation, as well as for the blood samples required for the ET assay. After induction of standard endotracheal anesthesia, pulmonary and radial artery catheters were placed. The patient was placed on standard CPB, and the heart was arrested with cold blood cardioplegia using both antegrade and retrograde routes of administration. Upon valve inspection, it was observed that there was circumferential thrombus around the St. Jude ring with extension of the thrombus into the main flow channels of the valve, thereby restricting leaflet motion. The thrombosed valve was excised and replaced with another 31-mm St. Jude valve. The heart regained sinus rhythm spontaneously, and the patient was weaned from CPB with low-dose epinephrine for inotropic support. Total cross-clamp and CPB times were 104 and 152 minutes, respectively. The patient was decannulated, chest tubes were placed, and the sternum was closed. The patient was transferred to the intensive care unit in stable condition.
At specific time points throughout the perioperative period, arterial and venous blood samples were obtained from the radial and pulmonary artery lines, respectively. Only venous samples were collected during CPB. After postoperative removal of the pulmonary artery catheter, an arterial sample was obtained at 36 hours postoperatively. The sample collections and ET assays were performed as described previously [6]. The measured levels of plasma ET were then corrected for possible hemodilution by normalizing to the baseline hematocrit, and the results are summarized in Figure 1. Briefly, pre-CPB and CPB plasma ET levels were consistently elevated above baseline levels. Further elevations in both venous and arterial plasma ET levels occurred after weaning from CPB, increasing by 304% and 267%, respectively, at 24 hours postoperatively. At 36 hours postoperatively, the arterial plasma ET level remained elevated at 165% above the baseline value.
View larger version (24K):
[in this window]
[in a new window]
|
Fig 1. Perioperative changes in venous and arterial plasma endothelin levels in a gravid patient undergoing mitral valve replacement. Plasma endothelin levels before and during cardiopulmonary bypass (CPB) were consistently elevated above baseline levels. Further elevations in plasma endothelin level occurred after weaning from CPB, with levels increased to more than twice the baseline level at 24 hours postoperatively. At 36 hours postoperatively, arterial plasma endothelin level decreased, yet remained elevated above baseline levels.
|
|
On postoperative day 1, the patient was extubated, and on postoperative day 2, chest tubes were removed. At this time, fetal ultrasound documented a viable fetus. The patient was started on a regimen of low-molecular-weight heparin and discharged on postoperative day 11. A subsequent ultrasound 4 weeks postoperatively documented positive fetal movement and normal cardiac activity.
|
Comment
|
|---|
The present case report described the temporal changes in plasma ET levels that occurred in the early postoperative period with the institution of CPB in a gravid patient. Specifically, plasma ET levels increased more than twofold and remained elevated in the first 36 hours postoperatively. Similarly, Knothe and associates [5] demonstrated twofold increases in plasma ET levels in nongravid patients after cardiac operations with CPB. In the gravid patient undergoing CPB, the postoperative period may be associated with fetal loss [1]. Specifically in a review of mitral valve replacement operations in the gravid patient, a relatively high incidence of spontaneous abortion in the early postoperative period was noted [1]. In the present case, a favorable postoperative outcome was achieved for both the patient and the fetus. Nevertheless, elevated plasma ET has been identified in various disease states including preeclampsia [7] and pulmonary hypertension [8], and the contributory role of increased ET levels with respect to postoperative complications remains to be defined.
|
Acknowledgments
|
|---|
Supported by National Institutes of Health grant HL-45024. Doctor Spinale is an Established Investigator of the American Heart Association. Scott B. Kribbs is a Medical Student Research Fellow of the American Heart Association.
|
References
|
|---|
- Becker R.M. Intracardiac surgery in pregnant women. Ann Thorac Surg 1983;36:453-456.[Abstract]
- Rushton D.I. Placental pathology in spontaneous miscarriage. In: Beard R.W., Sharp F., eds. Early pregnancy loss: mechanisms and treatment. New York: Springer-Verlag, 1987:149-157.
- Myatt L. Current topic: control of vascular resistance in the human placenta. Placenta 1992;13:329-341.[Medline]
- Myatt L., Brewer A.S., Brockman D.E. The comparative effects of big endothelin-1, endothelin-1, and endothelin-3 in the human fetal-placental circulation. Am J Obstet Gynecol 1992;167:1651-1656.[Medline]
- Knothe C.H., Boldt J., Zickmann B., Ballesteros M., Dapper F., Hempelmann G. Endothelin plasma levels in old and young patients during open heart surgery: correlations to cardiopulmonary and endocrinology parameters. J Cardiovasc Pharmacol 1992;20:664-670.[Medline]
- Thomas P.B., Liu E.C.K., Webb M.L., Mukherjee R., Hebbar L., Spinale F.G. Evidence of an endothelin autocrine loop in cardiac myocytes: relation to contractile function with congestive heart failure. Am J Physiol 1996;40:H2629-H2637.
- Nova A., Sibai B.M., Barton J.R., Mercer B.M., Mitchell M.D. Maternal plasma level of endothelin is increased in preeclampsia. Am J Obstet Gynecol 1991;165:724-727.[Medline]
- Stewart D.J., Levy R.D., Cernacek P., Langleben D. Increased plasma endothelin-1 in pulmonary hypertension: marker or mediator of disease?. Ann Intern Med 1991;114:464-469.
This article has been cited by other articles:
|
|
|
|
 
C. A. Walker, F. A. Crawford Jr, and F. G. Spinale
MYOCYTE CONTRACTILE DYSFUNCTION WITH HYPERTROPHY AND FAILURE: RELEVANCE TO CARDIAC SURGERY
J. Thorac. Cardiovasc. Surg.,
February 1, 2000;
119(2):
388 - 400.
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
