Stuck mechanical prosthetic mitral valve is a disease with a high mortality rate after the onset of symptoms in untreated patients. Moreover, stuck mechanical prosthetic mitral valve during pregnancy is a rare and catastrophic disease that leads to extreme lethality of mothers and babies. Here, we present a case of stuck mechanical prosthetic mitral valve that underwent moderate hypothermic circulatory arrest valve replacement surgery in 67 hours after the cesarean section. Postpartum hemorrhage did not happen during the systemic heparinization situation in and after the replacement of stuck valve leaflet with cardiopulmonary bypass (CPB). Written consent for the use of case presentation and figures, and consent for publication in print and electronically has been given by the patient.
A 37-year-old pregnant woman (gravida 2, para 1) at the 29 weeks of gestation was admitted to our cardiovascular department, who complained of dyspnea half a month, aggravating 7 days.
History of present illness
The patient was admitted to the respiratory department with cough, shortness of breath for 5 days, yellow phlegm for 3 days with hemoptysis 4 days before this admission. Diagnosed by severe pneumonia, lung edema, bilateral pleural effusion, type I respiratory failure, heart failure, rheumatic heart disease, mitral valve replacement, moderate pulmonary hypertension, left atrium enlargement, 28+5 weeks of gestation, gravid 2, para 1, breech position. The patient was administrated anti-inflammatory, expectorant, anti-asthmatic, aerosol inhalation and other symptomatic treatment, and suggested termination of pregnancy. She refused the termination and 3 days later, she asked to be discharged. On the next day after she was discharged from the hospital, she was admitted to the cardiology ward by the emergency department with dyspnea again. This new admitted diagnosis was valvular heart disease, mitral valve replacement, acute heart failure, New York Heart Association class IV, pneumonia, pleural effusion, oliguria, 29 weeks of gestation. At the beginning of pregnancy diagnosis, the patient worried about the side effects of warfarin on the fetus, so she used low molecular weight heparin 0.4 mL, twice a day instead of warfarin. Irregular prenatal examination in the Obstetrics Department but once a month, the patient went to the cardiovascular department for the cardiac function evaluation.
History of past illness
The patient had a history of replacement of left prosthetic mitral valves 11 years ago for rheumatic heart disease.
History of family illness
The patient had no family history of illness.
The patient was 167 cm tall and weighed 60 kg (body mass index =21.51). The patient's temperature was 37.5 °C, heart rate was 119 beats per minute, blood pressure was 103/87 mm Hg, respiratory rate was 18 breaths/min, and oxygen saturation in room air was 95%–96% (continuous oxygen inhalation). Dyspnea, orthopnea, the weak breath sounds of both lung bases, and moist rales can be heard. There were prosthetic valves murmurs from the cardiac auscultation area of mitral valve. The pulses of both upper extremity arteries and dorsal arteries were equal. The bowel sounds were normal.
On admission, blood analysis revealed mild leukocytosis of 11.8 × 109/L with neutrophils (86.1%). D-dimer and serum procalcitonin levels were 1.49 mg/L and 0.09 ng/mL, respectively. Brain natriuretic peptide reached to 2 903 pg/mL, while hematocrit and hemoglobin were down to 32.7%, 108 g/L. In addition, platelet count, blood biochemistry, prothrombin, partial thromboplastin time as well as creatinine levels were normal.
Fetal ultrasound confirmed that the fetus was stable without distress. Chest computed tomographic revealed pulmonary edema except mediastinal lymphadenopathy, bilateral pleural effusion, left atrium, and left ventricle enlargement with pulmonary artery dilatation (Fig. 1). The image of bedside echocardiography with patient end sitting showed mechanical mitral stenosis with moderate regurgitation with little pericardial effusion, enlarged left atrium with full right heart, moderate tricuspid regurgitation while the small regurgitation of aortic valve. Ejection fraction was 50% and estimation of pulmonary artery systolic pressure by tricuspid regurgitation method was 71 mm Hg.
The patient was diagnosed with stuck mechanical prosthetic mitral valves, heart failure, New York Heart Association class IV, type I respiratory failure, severe pneumonia, pulmonary hypertension, bilateral pleural effusion, anemia, puerperium.
No improvement of heart failure after active treatment in the Cardiology Department, cesarean section was performed 50 hours after admission. The neonate was 1 400 g; Apgar score was 5 in 1 minute, 8 in 5 minutes, transferred to neonatal intensive care unit after the section. Sixty-four hours after cesarean section in the cardio surgery intensive care unit, transesophageal echocardiography showed that the mechanical mitral valve was not opened and closed properly, suspected thrombosis, and the spontaneous development of left atrium and auricle was negative, no obvious clot thrombus was found. Three hours later, the other operation was ready for her.
Before this operation, the patient was in the cystolithotomy position in case of vaginal bleeding for the obstetrician to put the balloon into the uterine. The vagina was sterilized before operation to ensure that there is no obvious blood secretion. After that, a long gauze strip was placed at the vagina mouth, and a plastic pad placed at the buttocks to guide the strip to the leg stand side of the operating table. If it was bleeding from the uterine during the operation, the blood will flow to the vaginal opening, and will be absorbed by the long gauze, and the plastic pad will drain the blood to the observation side. The color change of the long gauze strip was observed until the operation was completed.
In brief, a median sternotomy was performed under deep hypothermic circulatory arrest, then the replacement of the stuck mechanical prosthetic mitral valves (Fig. 2). CPB was gradually resumed to normal flow and rewarming started. The times of CPB, aortic cross-clamp were 152 minutes, 62 minutes respectively. During the surgery, we also monitored the gauze strip in the vagina as a guider whether it was damp due to blood. No vaginal bleeding was observed during the procedure.
Outcomes and follow-up
The times of mechanical ventilation and intensive care unit stay were 18 hours and 88 hours, respectively. The patient received oral administration of Betaloc to control heart rate, blood pressure, and warfarin to anticoagulation after the surgery. The postoperative course was uneventful, and she was discharged at 11 days postoperatively (Fig. 3). There was little lochia during the puerperium. The neonate was discharged 33 days after birth.
Pregnancy combined with heart disease is the second leading cause of death in China, which is the most common indirect obstetric cause of death. The incidence rate is 1%–4% worldwide and about 1% in China. It should still be alert to the occurrence of heart failure during the delivery and in the postpartum.1
Prosthetic heart valves have been used to treat patients with both congenital and acquired valve lesions since the first surgical replacement in 1960.2 During pregnancy, there are series of adaptive changes in maternal circulatory system: an increase in heart rate, stroke volume, and cardiac output. These hemodynamic changes can lead to decompensation in women with prosthetic heart valves. Pregnancy is associated with additional risks in women with mechanical heart valves as pregnancy is a prothrombotic state with an increased risk of thromboembolic complications2 and hemorrhagic complications.
European Society of Cardiology Guidelines for the management of cardiovascular diseases during pregnancy (2018) showed that in women with mechanical valves, pregnancy is associated with a very high-risk of complications (World Health Organization risk classification III).3 The chances of an event-free pregnancy with a live birth were 58% for women with a mechanical valve, compared with 79% for women with a bioprosthesis and 78% for women with heart disease but no valve prosthesis.4 But Liu currently reported that maternal mortality for cardiac operations is similar to the mortality rate for non-pregnant female patients.5
At puerperium, it will take 6 weeks to repair endometrium. In the early stage, the blood is still in the state of hypercoagulation, which is beneficial to the formation of thrombus in the wound of placenta detachment and the reduction of postpartum hemorrhage. If during the period of repair, thrombus falls off due to the poor involution of placenta attachment surface, and the blood sinus is reopened, it may lead to uterine bleeding.
The mother need undergo emergency heart valve replacement. During operation, the whole body must be heparinized because of CPB. It means that heparin may dissolve any blood clots in the whole body. Therefore, the fatal effect of heparinization on parturient women is potential uterine bleeding.
At that time, obstetricians were facing great challenges. Before operation, if the uterine cavity should be compressed by balloon to prevent bleeding, it may destroy the thrombus in the placental attachment and cause new bleeding points. When heparinization of the whole body occurs, the newly formed bleeding spot would cause extensive bleeding of the uterus. Was that true? Sure! Under normal physiological conditions, that must happen.
CPB is to drain the venous blood from the body for oxygenation, and then the oxygenated arterial blood is transfused back to the body to maintain the blood oxygen supply of all parts of the body. During the operation, poor oxygenation, low blood oxygen saturation, and oxygen partial pressure caused tissue hypoxia. Insufficient perfusion flow caused tissue ischemia and hypoxia.
CPB is an artificially controlled shock state and it is also considered as a strong stimulation from outside, which can induce uterine contraction. During the CPB, hypotension, hypothermia and rewarming, and dilution of pregnancy hormones such as prostaglandins are all factors that promote uterine contraction. Mooij and colleagues monitored uterine activity during CPB in a patient who underwent aortic valve replacement while 24 weeks pregnant.6 Other investigators have also described the onset of uterine contractions during CPB.7 The cause of these contractions is uncertain, but some have been associated with hypothermia and rewarming. Hypothermia is frequently used during CPB to improve myocardial preservation and to decrease systemic oxygen demands. Little research has been performed in this area, and most of the information has been obtained from case reports or small series of patients. In pregnant dogs, cooling to 28°C resulted in increased uterine tone, a subsequent increase in uterine vascular resistance, and a decrease in uterine blood flow.8
Many studies have shown that even mild hypothermia can increase the tension and contraction of the uterus and the impedance of uterine blood vessels. Uterine contraction usually occurs during the rewarming period of moderate and severe hypothermia, and the higher the incidence, the more of gestational weeks.9,10
The mother must understand that the use of Vitamin K antagonist (VKAs) – warfarin is the most effective regimen to prevent valve thrombosis, and therefore the safest regimen for her and those risks to the mother also jeopardize the baby. However, the increased risks of embryopathy, fetopathy, fetal loss, and fetal hemorrhage associated with the use of VKAs need to be discussed while considering the VKA dose. The higher risk of valve thrombosis and lower fetal risks associated with low molecular weight heparin should be discussed. Compliance with prior anticoagulant therapy should be considered. The mother should understand that whatever anticoagulation regime is chosen, her strict compliance is crucial for a successful outcome of the pregnancy.
Concerning about valvular replacement, lots of papers talked about it during pregnancy, but seldom paid attention to it in the early puerperium. Postpartum hemorrhage is an important cause of maternal death. To prevent uterine bleeding, Yang et al. suggested that a hysterectomy should be actively performed after cesarean section.11 Zhu thought the insertion of a Cook balloon was safe and effective in reducing secondary damage.12 Uterine artery embolization and binding are suitable for dystonia of uterus not for coagulopathy. Thanks to the CPB induced uterine contraction, hypotension, hypothermia, and vasoactive drugs, there was little bleeding from the uterine with doing neither of them.
Whether this method is suitable for every parturient woman, it is worth further study. In conclusion, cardiac surgery during pregnancy and postpartum is an infrequent but challenging problem.
In conclusion, hysterectomy is not necessary to prevent bleeding during the CPB. As usual, the ways to guard against postpartum hemorrhage is the most important.
Conflicts of Interest
. Xie X, Kong BH, Gou WL. Obstetrics and Gynecology. 9th
ed.Beijing: People’ Medical Publishing House; 2018.
. Bhagra CJ, D'Souza R, Silversides CK. Valvular heart disease and pregnancy part II: management of prosthetic valves. Heart 2017;103(3):244–252. doi:10.1136/heartjnl-2015-308199.
. Regitz-Zagrosek V, Roos-Hesselink JW, Bauersachs J, et al. 2018 ESC guidelines for the management of cardiovascular diseases during pregnancy. Eur Heart J 2018;39(34):3165–3241. doi:10.1093/eurheartj/ehy340.
. van Hagen IM, Roos-Hesselink JW, Ruys TP, et al. Pregnancy in women with a mechanical heart valve: data of the European Society of Cardiology Registry of Pregnancy and Cardiac Disease (ROPAC). Circulation 2015;132(2):132–142. doi:10.1161/CIRCULATIONAHA.115.015242.
. Liu Y, Han F, Zhuang J, et al. Cardiac operation under cardiopulmonary bypass during pregnancy. J Cardiothorac Surg 2020;15(1):92. doi:10.1186/s13019-020-01136-9.
. Mooij PN, de Jong PA, Bavinck JH, et al. Aortic valve replacement in the second trimester of pregnancy: a case report. Eur J Obstet Gynecol Reprod Biol 1988;29(4):347–352. doi:10.1016/0028-2243(88)90076-7.
. Strickland RA, Oliver WC Jr, Chantigian RC, et al. Anesthesia, cardiopulmonary bypass, and the pregnant patient. Mayo Clin Proc 1991;66(4):411–429. doi:10.1016/s0025-6196(12)60666-1.
. Assali NS, Westin B. Effects of hypothermia on uterine circulation and on the fetus. Proc Soc Exp Biol Med 1962;109:485–488. doi:10.3181/00379727-109-27243.
. Parry AJ, Westaby S. Cardiopulmonary bypass during pregnancy. Ann Thorac Surg 1996;61(6):1865–1869. doi:10.1016/0003-4975(96)00150-6.
. Liu CM, Ding ZN. Pregnancy and cardiopulmonary bypass (In Chinese). Int J Anesthesiol Resuscitation 2003;24(1):53–55.
. Yang Z, Yang S, Wang F, et al. Acute aortic dissection in pregnant women. Gen Thorac Cardiovasc Surg 2016;64(5):283–285. doi:10.1007/s11748-014-0460-4.
. Zhu JM, Ma WG, Peterss S, et al. Aortic dissection in pregnancy: management strategy and outcomes. Ann Thorac Surg 2017;103(4):1199–1206. doi:10.1016/j.athoracsur.2016.08.089.