| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 1997;63:915-916
© 1997 The Society of Thoracic Surgeons
Department of Cardiothoracic Surgery Bombay Hospital and Medical Research Centre Bombay 400020, India
To the Editor:
We read the article "Cardiopulmonary Bypass in Pregnancy" by Pomini and associates [1] with great interest. We had a case of emergency redo mitral valve replacement for a stuck valve in a 5-months' pregnant woman in September 1995. Both maternal and fetal outcome was good. Such cases are not very common, so we would like to report to you in the context of the aforementioned article.
A 25-year-old woman who had experienced amenorrhea for 5 months presented with acute pulmonary edema and cardiogenic shock. She had rheumatic fever at 9 years of age. She was operated on for mitral valve replacement (25-mm Björk-Shiley valve) when she was 15 years old. She had two spontaneous abortions and was treated for the same for 3 years, so the present pregnancy was precious for her. On clinical examination she had acute pulmonary edema. On auscultation, valve click was absent. Two-dimensional echocardiography and fluoroscopy suggested a stuck mitral disc prosthesis in the open position with a mean gradient of 23.5 mm Hg across the valve with regurgitation. She also had moderate tricuspid regurgitation and moderate pulmonary hypertension. Her prothrombin ratio was 2
times normal. She was deteriorating very fast. Thrombolysis was not an option. Before we received consent for an operation and arranged for the operating room and blood transfusions, we had to put her on ventilatory support and perform management of pulmonary edema. She was in extensive metabolic as well respiratory acidosis and had cardiac arrest once but revived well.
Before the operation, fetal heart sounds were present and the uterus was relaxed. Considering the gravity of the situation our prime aim was to save the mother, although we had taken measures for the fetus also. We decided to go ahead with our routine protocol, which has given us good results for redo valve operations (7.2% in-hospital mortality). The patient was in the supine position. After median sternotomy, cardiopulmonary bypass (CPB) was established first on a single venous cannula and then on both venous cannulas to prevent sudden hypotension. The mean arterial pressure was kept 65 to 70 mm Hg, and flow was maintained at 2.5/L·min-1·m-2 with moderate hypothermia (28°C). Cold blood antegrade and retrograde cardioplegia was used for myocardial protection. Through a transseptal approach the 25-mm Björk-Shiley valve was explanted and replaced with a 23-mm Medtronic Hall valve as the left ventricular cavity was small. There were no clots in the left atrium. Pannus was present, and the valve was stuck in open position. The aortic cross-clamp time was 35 minutes, and the total CPB time was 1 hour 10 minutes. The patient was weaned off CPB on dopamine and nitroglycerin support.
Immediately after the operation the fetal heart sounds were normal and the uterus was relaxed. Fetal movements on abdominal ultrasonography were normal. Perioperative regular fetal monitoring was done and no episode of bradycardia was noted. The patient was extubated the next day. She was discharged from the hospital on the 14th day with oral anticoagulants as before. Later fetal growth was monitored and was normal without congenital anomaly. A full-term caesarean section was done, and a healthy (3.4 kg) female baby was delivered in January 1996, who is now 6 months of age with normal milestones.
As several fetuses did well during CPB and after delivery, it is possible to maintain the fetus in good condition at baseline flow (2.5 L·min-1·m-2) of the patient. As such there is no direct information available that an increased quantity of flow leads to a good fetal outcome especially in the second trimester. We kept the mean arterial pressure 65 to 70 mm Hg on CPB considering that would help the fetus [1, 2]. The fetus maintains the capacity to autoregulate its heart rate during moderate hypothermia also [3]. We believe that keeping the patient on ventilatory support meanwhile had helped to stabilize her preoperatively. As mentioned earlier, we managed the patient with our routine protocol. It differs from the practical advice given in the review by Pomini and associates; still, in the worst of circumstances, it is possible to revive both mother and fetus.
References
Department of Obstetrics and Gynecology Università Cattolica del Sacro Cuore L.go Gemelli No 1, 00168 Rome, Italy e-mail:fpomini{at}mix.it
Reply
To the Editor:
Thank you for giving us the opportunity to discuss this important topic.
We refer to the case report of a mitral operation with the aid of cardiopulmonary bypass (CPB) in a mid-trimester pregnant woman. The risk of maternal death made surgical intervention imperative. We congratulate Dr Kole and co-authors for their clinical skill, which resulted in a healthy mother and neonate.
Let us underline some points. (1) A supine maternal position, not on the flank, is probably adequate for the gestational age in question. (2) The optimal management during cannulation limited the degree of hypotension. (3) Fetal monitoring was not used during CPB. Cardiotocography would have been useful for several reasons: (A) The data in the literature on fetal conditions under CPB are very scant, especially as regards the correlation with maternal hemodynamics. (B) Cardiotocography during CPB is useful in fetal distress diagnosis, and in its treatment [1]. In fact, in several case reports, abnormal cardiotocographic results were normalized by raising the flow and mean arterial pressure [1]; the fact that often this does not occur makes fetal monitoring during CPB all the more important as an aid to comprehension. (C) Cardiotocography gives prominence to the uterine contractions often present during CPB, and thus enables us to treat them and the superimposed fetal distress.
The mean arterial pressure of 65/70 mm Hg used by Kole and associates is around the average for women at 20 weeks' gestation, and pump flow was the same as that of the patient before the operation. It is probable, in view of the positive outcome, that the amount of blood delivered to the placenta was adequate. But without fetal monitoring during CPB this cannot be known with certainty, even though low fetal hypoxygenation could in theory damage a weaker fetus.
(4) Cardiopulmonary bypass was conducted on moderate hypothermia (28°C). The same protective effects acting on maternal tissue probably also act on the fetus, but the effects on the placenta are completely unknown [1]. The external oxygenator is designed to function also on hypothermic blood, but the placenta probably is not. There are experimental data that indicate that placental functions (respiratory gas transfer) are reduced under hypothermia [2–5]. Other negative effects can be mediated by the raise in myometrium tone that occurs especially during the rewarming phase [1]. Analysis of case reports suggests that fetal morbidity and mortality is higher if CPB is performed under hypothermia of less than 35°C [1]. In a recent case report in which the fetus had been monitored with color Doppler ultrasound during CPB, the authors emphasized the importance of avoiding hypothermia during CPB [6].
We compliment Kole and associates for their surgical skill and for their willingness to publish the case.
References
This article has been cited by other articles:
|
|
 |
|
  S. Chandrasekhar, C. R. Cook, and C. D. Collard Cardiac Surgery in the Parturient Anesth. Analg., March 1, 2009; 108(3): 777 - 785. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
