Cardiac surgery under cardiopulmonary bypass in pregnancy: report of four cases

The incidence of heart disease in pregnant women is 1–4% approximately [1]. Heart disease complicates more than 1% of pregnancies and accounts for 15% of maternal mortality, the leading cause of indirect obstetric deaths [2, 3]. Even in developed countries, the maternal mortality rate has not declined either [2]. Pregnancy is an important factor that aggravates undetected heart disease and makes pregnant women show obvious symptoms. Due to the lack of medical and knowledge and awareness, heart disease in pregnant women is often not detected until the hemodynamic decompensation stage. At this point, cardiac surgical intervention is inevitable [4]. In principle, the cardiac surgical procedures should be avoided during pregnancy, preferably at 6 weeks after delivery. However, when these pregnant women develop obvious symptoms, early intervention of cardiac surgical procedures during pregnancy is necessary. Setting up a multidisciplinary team (MDT) for management is a crucial step, which is also consistently recommended in the guidelines developed by the European Society of Cardiology (ESC). As a countrywide intensive maternal care center in China, our hospital often has such special cases of heart disease during pregnancy, but only a small number of pregnant women undergo cardiac surgery under CPB during pregnancy. To provide more clinical treatment experience, including preoperative, intraoperative, and postoperative points of concern, we reported these four cases, which successfully underwent cardiac surgery under CPB during pregnancy.

IE is a fatal disease, which is relatively rare in clinical, but with a high mortality and disability rate [5]. Especially in pregnant women, IE has a high incidence of adverse maternal outcomes, as well as infant loss. Treatment and management of pregnancy-related infective endocarditis should be individualized and multidisciplinary. For example, whether open heart surgery is needed, staging or concurrent surgery, the effect of CPB on the fetus in staging surgery, the operation sequence of concurrent surgery, and intraoperative monitoring points. Additionally, the type of heart disease, severity, cardiac function, gestational age, the wishes of the patients and their family should also be considered [6]. Currently, the experience of clinicians in the treatment of pregnancy-related IE is still insufficient. Here, we reported four cases with heart disease during pregnancy who both underwent cardiac surgical procedures under CPB. Two of the patients underwent simultaneous cardiac surgery and cesarean section, that is cardiac surgical procedures 2 or 2.5 hours after cesarean section, and another two patients continued their pregnancies after cardiac surgery under CPB. In the four cases, the minimum gestational age was 23 weeks and the maximum was less than 37 weeks. Three patients with IE underwent MVR, and one patient with ascending aortic aneurysm underwent Bentall surgery. All these four cases were mechanical valves. Cases 1 and 2 underwent staging heart surgical procedures for fetal protection due to their small gestational age. Progesterone was used to suppress uterine contractions after surgery, while magnesium sulfate and atosiban were used for fetal protection. Fetal heart rate (FHR) was closely monitored during cardiac surgery and continued until the time of labor to ensure fetal stability and to avoid premature delivery. And the department of obstetrics was also involved in the management of postoperative monitoring and treatment of the fetuses. Through follow-up, we learned that the pregnant woman in Case 1 delivered a baby girl naturally at 36 weeks gestation, while another pregnant woman in Case 2 delivered a baby boy by cesarean section at 40 weeks gestation. Staged surgery requires more and more complex monitoring and evaluation, including preoperative, intraoperative, and postoperative. For example, the indications and timing of surgery should be evaluated according to the patient's condition; FHR should be monitored continuously, the duration of CPB should be reduced, and the perfusion flow and pressure of CPB should be improved during the operation; anti-infective therapy should be continued until 6 weeks after operation. For these two patients who continued pregnancy after cardiac surgery, they needed a higher cardiac output to maintain a higher cardiac index (CI). After surgery, we gave them a component blood transfusion, albumin supplementation, nutritional enhancement, and vasoactive drugs to run a higher CI. Therefore, open heart surgery in pregnant women is usually avoided and ideally delayed until 6 weeks postpartum [7]. However, when pregnant women develop obvious symptoms, early cardiac surgical intervention is the best option, and heart valve replacement is the first choice. In the four cases we reported, three of the patients developed life-threatening symptoms and the other one was a high-risk ascending aortic aneurysm. Thus, we formed the MDT, including departments of obstetrics, cardiac surgery, anesthesiology, intensive care, neonatology, and medical services, to discuss the treatment options that would be most beneficial to patients. CPB has a great influence on the fetus, the main influencing factors include the time of CPB heparinization, perfusion fluid temperature, perfusion flow and pressure, as well as maternal temperature. In the case that open heart operation is inevitable for pregnant women, anesthesia management, CPB management, intraoperative fetal monitoring and perioperative management are particularly important [8]. In the two cases reported in our report, with the cooperation of the surgeon, anesthesiologist and nurses, the operation time was only about 4 hours, which greatly reduced the time of CPB and kept the perfusion fluid at room temperature of 35℃ to the greatest extent to reduce the adverse outcome of low temperature on the fetuses. The perfusion was performed with high flow, high pressure and high hematocrit, and the FHR was monitored by Doppler ultrasound throughout the operation. Fetal death most often occurs during the cooling and rewarming phases of CPB [8]. Thus, the risk of fetal death can be greatly reduced by performing the operation at room temperature and controlling the temperature changes during the diversion. In these two patients, the temperature variation during CPB cooling and rewarming was 34.1–36.2 ℃ (the average temperature was 35.2 ℃) in case 1 and 34.8–36.4 ℃ (the average temperature was 35.6 ℃) in case 2. Low molecular weight heparin was used in the early stage of the operation, and warfarin was used until about one week before parturition when the condition of the pregnant women and the fetuses were stable, so that the prothrombin international ratio was maintained at 2.0–3.0. Imipenem combined with vancomycin was also used for anti-infective therapy until 6 weeks after surgery. Of course, the fetuses need to be continued to be closely monitored postoperatively. Case 3 was a patient at 33 weeks of pregnancy, diagnosed with ascending aortic aneurysm complicated with severe aortic valve insufficiency. CTA examination indicated that the dilated diameter of the ascending aorta was more than 8cm, and her immediate family members, her aunts and uncles, had a history of Marfan syndrome. She is at high risk during pregnancy, and early cardiac surgery intervention is needed. Cases 3 and 4 both underwent cesarean section and heart valve replacement at the same time, and both mother and fetuses survived. CPB has a greater impact on the fetus and the fetal mortality rate is high, ranging from 16 to 33% [8]. Therefore, the study of Chandni Patel et al recommended that cesarean section be performed prior to CPB-MVR to improve fetal outcome [8]. Simultaneous cardiac surgery and cesarean section, like cases 3 and 4 in our report, should also consider the increased risk of postpartum bleeding as an important risk factor, which may cause pregnant women to lose their uterus. In the two cases we reported, we used uterine balloon tamponade and bilateral uterine artery ascending branch ligation, combined with intravenous drops of oxytocin to prevent massive postpartum hemorrhage. Replacement of heart valves 2 or 2.5 hours after a cesarean section is also a key step in reducing postpartum bleeding in pregnant women. Reducing the aortic cross-clamp time and CPB time also do help to reduce the risk of cardiac surgical procedures and complications in pregnant women. In these four cases we reported, anti-coagulation on CPB was also using activated clotting time (ACT) monitoring. ACT is considered the gold standard in monitoring anti-coagulation for CPB [9]. Bull and colleagues’ study showed no development of clots in the oxygenator or circuit when ACT was maintained above 300 s [9]. In our study, we maintained ACT above 480 s. After systemic heparinization, CPB was started after ACT reached to 480 s. For the selection of drugs commonly used in cardiac surgery, we routinely followed the guidelines and there were no particular drugs that we had to avoid.

We have successfully performed cardiac surgery under CPB for four pregnant women with heart disease during pregnancy. Two of them were performed simultaneous cardiac surgery and cesarean section, and the other two continued their pregnancies after cardiac surgery. All four patients survived, both mothers and fetuses. These four cases we reported show that surgical interventions should be carried out actively and proactively for heart disease during pregnancy with obvious symptoms. Of course, we should be careful about the occurrence of postoperative complications. Collaborative management of multidisciplinary teams is a good way.