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Ann Thorac Surg 2003;76:1605-1608
© 2003 The Society of Thoracic Surgeons

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Original article: cardiovascular

Risk factors associated with cardiac surgery during pregnancy

^a Instituto Dante Pazzanese de Cardiologia, São Paulo, Brazil

Accepted for publication July 1, 2003.

^* Address reprint requests to Dr Arnoni, Rua Jesuíno Arruda, 318 apto 121, Itaim Bibi, São Paulo, Brazil, CEP 04532-080
e-mail: ramoni{at}uol.com

	Abstract

Top Abstract Introduction Patients and methods Results Comment Acknowledgments References

 
BACKGROUND: This study is aimed at analyzing risk factors for fetal and maternal mortality in cardiac surgery during pregnancy.

METHODS: Seventy-four pregnant women underwent cardiac surgery and 58 (78.3%) were followed. The most frequent pathology was valve disease (93.2%). Mitral valve disease was the most prevalent (72.9%), and mitral commissurotomy or replacement was required in 78% of the cases. Most were in functional class III or IV and mean gestational age was 22 weeks.

RESULTS: There was functional class improvement after surgery (91% into class I or II), and 70.4% were restored to sinus rhythm. Twenty percent required reoperation. There were five maternal deaths (8.6%) and 11 fetal deaths (18.6%). Several aspects were considered as contributing risk factors for maternal mortality, such as the use of vasoactive drugs and other preoperative medications, age, kind of surgery, reoperation, and functional class. Functional class was the factor that predicted higher risk for maternal death. As to fetal mortality, several factors played a role, such as maternal age more than 35 years, functional class, reoperation, emergency surgery, type of myocardial protection, and anoxic time.

CONCLUSIONS: Cardiac surgery during pregnancy is associated with acceptable maternal and fetal mortality rates. These rates may be even lower if the factors mentioned above are maintained under control.

	Introduction

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The incidence of heart diseases in pregnant women ranges from 1% to 4% [1], and rheumatic mitral disease is responsible for most cases (50%) [1, 2]. Some of these patients evolve into decompensation and require either surgery or interventional treatment during pregnancy.

Surgery in pregnant woman was initially described without extracorporeal circulation by Block in 1952 [3]. In 1959, Dubourg and associates [4] described surgical correction of Fallot's tetralogy using extracorporeal circulation to correct cardiac diseases during pregnancy. Other authors reported the use of this technique to treat other pathologies in pregnant women, such as aortic stenosis [5], mitral valve replacement [6], myocardial revascularization [7], and removal of left atrial myxoma [8].

On our service, the first surgery in a pregnant woman was carried out in 1964, when a patient with mitral stenosis underwent commissurotomy. It was not until 1985 that the Cardiopathy and Pregnancy Group was organized. It is a multiprofessional team aimed at improving the outcome of pregnant women [9].

The aim of this study was to identify maternal and fetal risk factors for patients undergoing corrective cardiac surgery during pregnancy.

	Patients and methods

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From 1964 to February 2002, 74 pregnant women underwent surgical treatment at "Instituto Dante Pazzanese de Cardiologia." Fifty-eight (78.3%) patients had early and late follow-up and are evaluated in this study. Most of the patients reported in this study were operated on between 1982 and 1991 (1972 to 1981, 2; 1982 to 1991, 34; 1992 to 2002, 22).

Ages ranged from 17 to 45 years, and mean age was 28 years. The most frequent pathology was valvular disease (93.2%), and was mitral stenosis in most patients (Table 1).

Most of the patients (54.3%) were multipara and gestational age varied. Most surgeries were carried out in the second trimester (42 patients), 2 patients were operated on in the first trimester, and the remaining patients in the last trimester of pregnancy.

The surgeries were: (1) elective, when the patient was not aware of her gestation or did not inform the physician about it (1 patient); (2) planned, in patients whose heart disease was difficult to control during pregnancy, when there was prosthesis malfunction, or embolic events in patients with a mechanical prosthesis (29 patients); or (3) emergency (18 patients), in patients with endocarditis (3 [16.7%]), acute pulmonary edema (7 [38.9%]), worsening of functional class (7 [38.9%]), and thrombosis of a mechanical prosthesis (1 [5.5%]).

Surgery was performed under general anesthesia in all patients. The anesthesia was performed with precurarization followed by the administration of Midazolam and diphenylhydantoin. The anesthesia was maintained by diphenylhydantoin and isoflurane; using isoxsuprine and terbutaline in continuous infusion to prevent uterine contractions. Hydralazine (vasodilatator) and dopamine (vasoconstrictor) were used for hemodynamic control during surgery. Alpha-adrenergic drugs such as adrenalin and noradrenalin were avoided to prevent excessive vasoconstriction, which may decrease umbilical flow and stimulate uterine contraction. Maternal monitoring followed the institution's general rules (invasive arterial pressure, electrocardiogram, urinary catheter, uterine contraction, and fetal heartbeat monitoring with cardiotachometer). In the last two cases, intrauterine echocardiography was used to control fetal heartbeat. Table 2 lists the procedures performed.

Hypertonic glucose was added to the extracorporeal perfusate to avoid fetal bradycardia [9]. Intermittent aortic cross-clamp (anoxia) with normothermia was used for myocardial protection whenever possible (mitral valve surgery and atrial myxoma). When cardioplegia was required, crystalloid cardioplegia was used with aspiration of the right atrium. Surgery was performed at normothermia, with topic ice placed over the heart for better protection. High flows were maintained during perfusion in all cases.

All procedures were performed by senior surgeons to minimize extracorporeal circulation distress and decrease perfusion and anoxia times. The shortest perfusion time was 24 minutes and the longest was 150 minutes (mean of 40.7 minutes); anoxic time ranged from 8 to 97 minutes (mean 24 minutes). The shortest perfusion and anoxic times were associated with mitral commissurotomy, carried out as an emergency procedure due to acute pulmonary edema. Both mother and fetus had a good outcome. The longest procedure was correction of an aneurysm of the ascending aorta with valve insufficiency; replacement of the ascending aorta by a valved tube and coronary ostia reimplantation were required.

The patients were followed by our Cardiopathy and Pregnancy Group for an average of 78 months. One patient has been followed for 260 months.

A retrospective analysis of our records was performed and was subjected to a statistical analysis in order to identify risk factors associated with maternal and fetal mortality. The statistical analysis of the qualitative variables was carried out by associating the variables two by two through either the ² or Fisher's exact test. For the quantitative variables, we used Student's t test (mean difference test). The significance level was 0.05. The multivariate analysis for independent variables was performed.

	Results

Top Abstract Introduction Patients and methods Results Comment Acknowledgments References

 
After surgery, most hearts resumed sinus rhythm (38 patients [65.5%]), with improvement in quality of life and significant improvement in functional class (50 patients [86.2%] in functional class I or II).

During the late follow-up period, 19.6% of the patients underwent a new surgical procedure (commissurotomy or valvular replacement). The maternal mortality rate in this group was 8.6%. Analyzing the outcomes in different decades, there were no maternal deaths between 1972 and 1981 (2 patients). In the second decade (1982 to 1991), 34 patients were operated on and 3 died (8.8%); and in the last decade (1992 to 2002), there were two deaths out of 22 operated patients (9.09%). The deaths were as follow. Two patients had endocarditis preoperatively. They underwent surgery in unfavorable conditions in functional class IV. One had had a previous cerebral event. One previously revascularized patient had venous grafts occlusion within 6 months after surgery and severe ventricular dysfunction. One patient died after mitral commissurotomy and De Vega tricuspid plasty, which evolved into early placenta displacement after surgery and hypovolemia. One late postoperative patient had cardiac decompensation in the postpartum period.

Fetal mortality occurred in 19 cases. However, 4 newborns died as a result of maternal death. One died 48 hours after birth as a result of sepsis. The mother did not have endocarditis. Of the mothers who died, only 1 newborn, whose mother died later, survived. Two children died later: one due to cerebral malformation, and the other died 2 months after the surgery as a result of premature delivery and postpartum complications. Another newborn died after birth due to incompatibility with the mother's blood type. The last fetus had not been moving for 3 days when surgery was performed and did not have fetal heartbeats; the mother had mitral stenosis with endocarditis and underwent emergency surgery in acute pulmonary edema. Therefore, eight out of 19 deaths were not related to surgery; this decreases the fetal mortality rate due to surgery to 18.6%.

The following variables were considered to assess risk factors associated with death: maternal age, preoperative medication, maternal disease, NYHA functional class, type of surgery (elective, planned, or emergency), reoperation, myocardial protection, anoxic and perfusion time, gestation (multiple with two or more abortions, multiple without abortions, and first pregnancy), gestational age (trimester), maternal age in categories (younger than 35 years and 35 years and older [this criterion was used because after this age, mothers are most likely to have gestational complications]).

The above tests showed a relationship between death and worse functional class. All deaths occurred in patients with functional class IV, p = 0.005 according to Fisher's test.

The other aspects analyzed were not associated with maternal death, and did not result in major maternal risks: age categories (p > 0.999), gestational age (p > 0.999), number of gestations (p > 0.999), reoperation (p = 0.574), type of myocardial protection (p > 0.999), and type of surgery (p = 0.314); however, 2 out of 3 patients who underwent emergency surgery due to endocarditis died.

The quantitative data did not show statistical significance for maternal age, perfusion time and anoxia. Analysis of maternal mortality showed further risk factors, and many were related to fetal deaths (Table 3). Other qualitative variables analyzed (gestational age [p > 0.999] and number of gestations) did not increase the fetal risk of death (p = 0.9).

Anoxic time related to fetal death was 35.7 minutes. Anoxic time not related to fetal death was 23.3 minutes (p = 0.035).

Perfusion time was not a major risk factor; the mean perfusion time in mothers whose fetuses died was 50.1 and 35.4 minutes, respectively (p = 0.089) for the ones whose fetuses had a good outcome.

Multivariate analysis indicated the following independent factors for fetal mortality: maternal age higher than 35 years (odds ratio, 7.5), reoperations (odds ratio, 7.4), and emergency surgery (odds ratio, 4.7) (95% CI)

	Comment

Top Abstract Introduction Patients and methods Results Comment Acknowledgments References

 
Surgery during pregnancy permits treatment of many diseases, including patients with valve disease, aneurysms, coronary disease, and myxomas, as described in this study [4, 5, 7, 8, 10, 11–13]. Valve disease is the most common, because in our environment, rheumatic valve disease is predominant, and affects women in the reproductive age range [10]

The ideal gestational age for operation is addressed by several authors [5, 14–17], who established the period between the 13th and 28th weeks as ideal. There is a higher trend towards fetal malformations in the first trimester, and to preterm delivery, maternal hemodynamic alterations, and mortality in the third. We followed this guideline in most patients. However, there was no relationship between maternal and fetal outcome and surgical indication according to gestational age, as reported by Westaby and associates [12].

Fetal monitoring, as reported by Lamb and associates [18] in 1981, allowed analysis of fetal condition during extracorporeal circulation. Fetal bradycardia was observed at the beginning of extracorporeal circulation by using a cardiotachometer [17]. To counter this phenomenon, Arnoni and associates [9], in 1986, used hypertonic glucose in the perfusate to increase the energy supply to the fetus. In addition to monitoring the fetus, uterine contractions must be controlled. Intraoperative fetal echocardiography shows the fetal cardiac reactions more accurately and is recommended.

Extracorporeal circulation is an important technique that causes significant alterations in the mother and fetus. Cardiopulmonary bypass causes alterations in coagulation, the release of vasoactive substances, activation of the complement system, air and particlular emboli, nonpulsatile flow, hypotension, and hypothermia [1]. Hypothermia may lead to uterine contractions and reduction of placental flow [19]. To reduce these risks, extracorporeal circulation with high flow, high pressures (mean blood pressure of 60 mm Hg), and normothermia should be used [9, 17, 20]. Hyperoxygenation should be maintained and hematocrit should be kept higher than 25%.

Some authors [18] report that myocardial protection using intermittent clamping allows, during normothermia, short perfusion times with pulsatile flow, which favors the fetus.

Maternal mortality rate varies in the literature from 1% to 5%, with an average of 2.5% [1, 10, 13, 19, 20], and does not differ from nonpregnant women with similar diseases. The higher incidence of fatal cases in our study compared with those reported in previous studies is a result of the poor preoperative condition of the patients. Patients who died had complications of their cardiac disease and ventricular dysfunction, which might have been avoided if they had earlier operation.

The fetal mortality, obtained by the "Instituto Dante Pazzanese de Cardiologia," is considered good; a mortality rate of about 18.6% is similar to that reported by other services. Pomini and associates [19] and Parry and Westaby [20] reported a mortality rate of 19% and 20.2%, respectively. On the other hand, Mahil and associates [1], in their review of several studies on this subject, reported a fetal mortality rate ranging from 16% to 33%.

Fetal mortality is described as higher than 50% in patients in functional class III and IV [21]. We found similar mortality rates in patients in functional class IV (66.7%) and much lower rates in functional class III (20%).

Heart surgery during pregnancy is associated with acceptable maternal and fetal mortality rates. These rates may be even lower if the factors mentioned above are maintained under control.

We suggest a few measures to reduce maternal and fetal mortality. These include avoiding functional deterioration during pregnancy, and perhaps prescribing earlier surgery to prevent these patients from requiring an emergency procedure; performing surgery as fast as possible, with minimal extracorporeal circulation time; providing adequate fetal monitoring (cardiotachometer and intraoperative fetal echocardiography); and performing surgery in the second trimester of pregnancy preferably.

	Acknowledgments

Top Abstract Introduction Patients and methods Results Comment Acknowledgments References

 
The authors thank Valéria Troncoso Balta from the Statistics Department, "Instituto Dante Pazzanese de Cardiologia."

	References

Top Abstract Introduction Patients and methods Results Comment Acknowledgments References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map 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 Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Arnoni, R. T. Articles by Paulista, P. P. Search for Related Content PubMed PubMed Citation Articles by Arnoni, R. T. Articles by Paulista, P. P. Related Collections Cardiac - other