Experience of two consecutive pregnancies after Fontan connection: anesthesiology and obstetrical aspects

Introduction

The Fontan procedure refers to any operation which results in the flow of systemic venous blood to the lungs without passing through a ventricle. It is performed to treat several complex congenital heart abnormalities including tricuspid atresia, pulmonary atresia with intact ventricular septum, hypoplastic left heart syndrome, and double-inlet ventricle. The original Fontan procedure included direct anastomosis of the right atrium to the main pulmonary artery; however, multiple modifications have been employed. The creation of Fontan circulation is palliative in nature, with good results in patients with ideal hemodynamics and substantial morbidity and mortality in those with poor hemodynamics. Complications of Fontan circulation include exercise intolerance, ventricular failure, right atrium dilatation and arrhythmia, systemic and hepatic venous hypertension, portal hypertension, coagulopathy, pulmonary arteriovenous malformation, venovenous shunts, and lymphatic dysfunction (e.g., ascites, edema, effusion, protein-losing enteropathy, and plastic bronchitis) [8].

In this paper we analyze our experience in two successful consecutive pregnancies of a patient with previous Fontan connections, describing the obstetrical, anesthes-iological, and cardiovascular events and a review of the literature.

Case report

A patient born in 1982 was referred twice to our department for pregnancy and delivery in 2004 and 2006. At 5 years of age surgical Fontan procedure was performed because of subvalvoular pulmonary stenosis, absence of tricuspid valve, and rudimental right ventricule. After this surgery she reported wellness for almost 15 years, except for three short episodes of rhythmic palpitation and blurred vision with spontaneous recovery.

She became pregnant in 2004, and she took aspirin 100 mg daily during the entire course of her pregnancy. Starting from 24 weeks she was monitored weekly by fetal ultrasound with ecocolordoppler and later by cardiotocography. Globally during this first pregnancy all obstetrics and cardiologic parameters were regular.

She delivered a healthy baby weighing 1900 g at 32 weeks of pregnancy by cesaren section because of onset of labour, due to the rising of uterine contractions, in breech fetal presentation. In this case general anesthesia was performed.

Clinical cardiologic assessment and echocardiography were done every 15 days; her left ventricular (LV) diameters and ejection fraction were stable.

Two years later she became pregnant again. Considering the previous premature birth the patient was monitored also for microbiological cervicovaginal screening resulting positive for ureaplasma urealyticum, which was medically treated by antibiotic therapy. Aspirin was given starting at 6 weeks of pregnancy. At 24 weeks she developed phrenospasm with paroxysmal tachycardia at 230 bpm with spontaneous recovery. At 26 weeks, with increasing dyspnea, she developed a presyncopal episode with high QRS tachycardia, regressing to low QRS 230 bpm frequency (rate) which later resolved, with adenosina endovenous hematological and chemical blood exams normal.

After this cardiac event, the patient started to have uterine contractions that were arrested with atosiban, and fetal lung maturation was performed. Fetal growth and Doppler parameters were strictly monitored. Because of the increased risk of thrombosis, the patient was treated with subcutaneous heparin preoperatively. At 33 weeks, because of onset of labor, a cesarean section with general anaesthesia was performed.

Before induction of anesthesia a central venous catheter was placed; an exaggerated left lateral tilt position was used to avoid aortocaval compression. After careful preoxygenation anesthesia was induced with pentothal 200 mg and sevoflurane 0.5%+N2O and O2, respectively, 40% and 60%. The delivery was 8 min later, and to continue anesthesia she received atracurium 25 mg + fentanyl 0.005 mcg and midazolam 5 mg.

Central venous pressure under mechanical ventilation was 16 mm Hg, while the heart rate varied between 60 and 90 bpm. Fetal outcome was good delivering a healthy baby weighing 1860 g, with an Apgar of 8–10. In the post-operative period, the patient was transferred to the intensive care unit (ICU) for 48 h to strictly monitor maternal parameters.

In the ICU, the patient was extubated 1 h postoperatively and continued on 40% oxygen therapy. Urine output was 130 mL/h and central venous pressure was 18 mm Hg after fluid infusion. She received apicillin/sulbactam 6 g/day plus gentamicin 320 mg/day to prevent endocarditis, morphine 20 mg for analgesia the first day followed by tramadol 150 mg the second day. Because of the scotomas she underwent an ophtalmological exam that revealed venous congestion. Because of the torpid peristalsis she received maleato trimebutine. She was discharged from the ICU to the obstetric ward.

Post-operative progress was without complications, and she continued subcutaneous heparin for 40 days. She was discharged on the eighth day after surgery and was advised to undergo an electrophysiology study at a regional cardiac center.

Conclusions

Prenatally it is advisable that all women with cardiac disease have one consultation in a specialized center for counseling, risk estimation, and formulation of a management plan. This should preferably take place before pregnancy, or otherwise as early in pregnancy as possible. It should be decided where the woman will receive cardiology and obstetric care during pregnancy. Three levels of care can be distinguished. These levels of care are comparable with the care recommended in the European Society of Cardiology (ESC) guidelines for the management of adult congenital heart disease and are modified for pregnant women with heart disease according to disease complexity and pregnancy risk [3]. Level 1 represents care for highly complex and high-risk (WHO class III or IV) lesions, for which exclusive care in a specialist unit is advisable, usually monthly or bimonthly. Level 2 represents care for moderately complex lesions and low to moderate risk of pregnancy (WHO II); these women can be managed in a shared care model by collaboration of a specialist and a regional cardiac and obstetric service and usually need cardiac follow-up once per trimester. Women with simple lesions and low pregnancy risk (WHO class I) are classified for level 3 care which means that they can be managed entirely in a regional hospital. For these women, cardiac follow-up can be limited to once or twice during the pregnancy. In all women with a pregnancy wish or who are pregnant, thromboembolic risk should be assessed according to the schedules presented in the ESC Guidelines for the management of cardiovascular diseases during pregnancy [14]. When applicable, thromboprophylaxis and/or compression stockings can be implemented when pregnancy occurs.

During pregnancy, standard cardiac follow-up for most women will consist of clinical assessment and echocardiography. In addition, depending on the underlying lesion and on symptoms, 24-h ECG monitoring can be performed. Exercise testing should preferably be performed prepregnancy to assist in risk estimation but can be performed in asymptomatic pregnant women to a heart rate of 80% of the maximal predicted heart rate [14]. It is evident that radiation must be avoided if possible, but for vital indications procedures involving radiation may be performed if no other possibilities are available. Radiation exposure of the fetus is limited for most procedures and acute fetal risk does not usually exist. Few data are available to judge the safety of magnetic resonance imaging during pregnancy, but it is probably safe at least after the first trimester and provided gadolinium is avoided [18].

Most women with heart disease like Fontan procedure frequently pursue pregnancy. Pregnancy induces hemodynamic changes, which include a 40% increase in plasma volume and cardiac output, as well as a marked reduction in systemic vascular resistance. In addition, hemostatic changes lead to hypercoagulability. The physiological changes of pregnancy are often well tolerated by women with heart disease but may also induce complications such as heart failure, arrhythmias and thromboembolic events [4, 6, 13, 15]. The peripartum period constitutes an extra risk, as during and after delivery cardiac demand increases due to uterus contractions, anxiety, pushing, autotransfusion of the contracting uterus post-delivery, and blood loss. The risk of pregnancy should be assessed before and during pregnancy, and the management of pregnancy and delivery must be planned accordingly [11, 14]. Adequate pregnancy management includes involvement of a multidisciplinary team that ensures appropriate and well-organized care during pregnancy and peri-partum. The core members of this team are the cardiologist and the gynecologist, and when delivery approaches the anesthetist and neonatologist. For some women a hematologist or a cardiac surgeon needs to be involved. It should never be forgotten that the general practitioner is an important member of the team who should be well informed about the course of the pregnancy, as he or she may get involved at any stage of the pregnancy and especially in emergency situations occurring outside the hospital. A nurse practitioner can be a very useful member of the team and can serve as a coordinator. Adequate communication among team members is of paramount importance. The cardiologist should formulate the cardiac risks of the pregnancy, and both the cardiologist and gynecologist must readily inform all team members about the results of examinations and about complications that occur [12].

Regarding mode of delivery, several studies show that cesarean section is performed more often in women with heart disease than in a healthy population [1, 19]. For most cardiac patients, however, vaginal delivery is preferred and cesarean section is reserved for obstetric indications, since cesarean section is associated with more blood loss and higher thromboembolic and infection risks. Examples of situations in which primary cesarean section should be considered are start of labor while on oral anticoagulants (because of risk of fetal intracranial bleeding), Marfan syndrome with diameter of the ascending aorta >45 mm, acute or chronic dissection, and acute heart failure [14]. When vaginal delivery is chosen, it should be decided whether the woman can be allowed to push or if an assisted vaginal delivery is preferable. The benefit of avoiding hemodynamic fluctuations resulting from pushing must be weighed against an increased risk of perineal trauma, hemorrhage, and fetal head injury with forceps or vacuum delivery. For most women, pushing may be preferred above primary assisted delivery [7].

Until 1996 only five pregnancies had been reported in the literature regarding women with previous Fontan procedure [10], and until 2003 only two patients after Fontan procedure were reported as having two successful deliveries [16]. Recently reports about this group of patients have been more frequently described.

Inoue et al. in 2013 [9] reported two cases of pregnancy and delivery with Fontan circulation. Case 1, who underwent Fontan procedure for congenital pulmonary atresia with intact vertical septum at age 7, delivered a male infant weighing 1073 g by cesarean section at 28 weeks [9, 14] due to massive genital bleeding. Case 2 underwent Fontan procedure for a double inlet left ventricle and delivered by vacuum extraction a male infant weighing 2142 g, while monitoring central venous pressure at 37 weeks [9, 11]. The former had ascites, and doses of diuretic had to be added in early pregnancy, and the latter had no adverse cardiac and obstetric events.

Recent analysis of the literature reports more and more frequently cases of premature delivery and Drenthen et al. [5] in 2006 referred premature delivery in 39% of 39 pregnancies accounted in his report, an extremely high rate considering the normal preterm rate. In the same article he reported 12.8% of small for gestational age births suggesting that there is not an increase of intrauterine growth retardation in patients with adequate univentricular circulation.

Conversely, Canobbio et al. [2] reported a median gestational age of 38 weeks, with only one preterm labor, which is in keeping with other data, such as those of Walker [17] in which only one of the five completed pregnancies delivering before the 37^th week. Canobbio reported on the largest Fontan pregnancy experience to date, of 33 pregnancies, where there were 15 live births and 13 spontaneous abortions.

Our report and review of the literature suggest that these patients are likely to have premature delivery and reduced intrauterine fetal growth. Most of these pregnancies proceed uneventfully, and therefore patients with Fontan repairs can be counseled about proceeding with pregnancy.

Further studies are needed to implement data and clinical experience, particularly regarding follow-up of these groups of patients after pregnancy, considering the potential harmful effect on cardiovascular function.