Cardiac operation under cardiopulmonary bypass during pregnancy

Heart disease complicates more than 1% of pregnancies and is now the leading cause of indirect maternal deaths [1]. Pregnancy creates a great burden on the cardiovascular system and can result in decompensation in women with underlying cardiac disease. To minimize the maternal and fetal risks, the first choice of treatment should be medical. In cases that are refractory to medical treatment, however, corrective cardiac operations should be undertaken [2]. As the Guangdong provincial obstetrical cardiology intensive care center in China, our hospital has accumulated a significant amount of clinical data of pregnant women with heart disease receiving cardiac operations under cardiopulmonary bypass during pregnancy. To investigate feto-neonatal and maternal outcomes, we conducted this study.

Heart disease is the primary cause of maternal and fetal death in 1–4% of pregnancies. Pregnancy creates an increased burden on the maternal cardiovascular system and can result in decompensation in women with underlying cardiac disease. To minimize the maternal and fetal risks, the first choice of treatment should be medical. However, in some cases, medical therapy is not always sufficient,and open heart operation might be necessary [4]. In 1958, Leyse and colleagues [5] first used cardiopulmonary bypass (CPB) in a heart operation during pregnancy. After the initial trials, pregnant women have been recognized to tolerate CPB as well as non-pregnant women, but the effects of CPB on the fetus have varied [6]. Several review articles, reported the maternal mortality rate ranged from 1.5 to 5%, and the fetal mortality rate has ranged from 16 to 33% [4, 6]. Currently, reported maternal mortality for cardiac operations is similar to the mortality rate for non-pregnant female patients [7]. Therefore, CPB during pregnancy has a greater effect on the fetus than mother. In our report, the maternal mortality rate was 0%,and fetal mortality rate was 18.2%, as same as the above mentioned reviews.

The present study demonstrated that mitral and/or aortic valve disorders were the most common surgical indications for CPB during pregnancy, although it has been recognized that coronary arterial disease is increasingly prevalent in gynecological patients [8]. The latter, however, could be managed interventionally in most patients, avoiding the risk associated with CPB for feto-neo-natal outcomes. In our report, the indications for surgical procedure under CPB during pregnancy consisted of congenital heart defect (ASD, DCRV, VSD), rheumatic heart disease (mitral or aortic valve disorders),infective endocarditis,aortic dissection, obstruction and thrombosis of the prosthetic valve. Seven patients (all with a congenital heart defect)accompanied moderate to severe PAH, which could result in sudden death and greatly increase the maternal and fetal risk. Consequently, we performed cardiac operations during pregnancy to maintain the pregnancy and to decrease the risk of adverse feto-neonatal outcomes. Other indications were life-threatening diseases, such as severe MS/AR, infective endocarditis,aortic dissection (Stanford type A), obstruction and thrombosis of the prosthetic valve. All patients were alive,and 3 cases had complicated arrhythmia after operations, especially atrial fibrillation. There were no other complications. The results indicate that cardiac operations can be performed during pregnancy with remarkable safety for mothers.

Pregnant women who have cardiac operations requiring CPB must face a nonphysiologic hemodynamic status where the tolerance is not clearly known, which can adversely affect the fetus [4]. CPB can compromise utero-placental perfusion and fetal development by potential adverse effects such as coagulation and blood component alterations, the release of vasoactive substances from leukocytes, complement activation, particulate and air embolism, nonpulsatile flow, hypothermia and hypotension [2].Three main pathophysiological changes can occur in pregnant patients under CPB: uterine contraction, placental hypo-perfusion and fetal hypoxia. Utero-placental hypo-perfusion and fetal hypoxia subjected to sustained uterine contractions during CPB are considered risk factors for fetal death [9]. Despite the limited experimental data regarding the effect of CPB on uterine/placental blood flow and its effect on the fetus, it has been postulated that pulsatile, high-flow, high-pressure, normothermic bypass poses the least risk to the fetus [10, 11].According to the above theories we applied high-flow, high-pressure, normothermic bypass to the patients and shortened the operation time to greatly decrease the influence on the fetus. Finally,the fetuses gained good outcomes,and the mortality rate was 18.2%, lower than that reported in recent literature. Fourteen fetuses were alive and born without any abnormity. Unfortunately, two fetuses suffered neonatal intracranial hemorrhage and died after birth. However, we do not think it was associated with the operation or the CPB during pregnancy. The inappropriate use of Warfarin after operations was the main cause. The results indicate that cardiac operations can be performed during pregnancy with a degree of safety for fetus.

In conclusion, the decision to subject a pregnant woman to operation must be made by a team composed of an obstetrician, a cardiologist, an anesthesiologist and a neonatologist. Cardiac operation under CPB during pregnancy is a challenge for physicians in multidisciplinary teams. Strictly evaluating the indication is vital. On the other hand, some patients can benefit from this form of case management.