Case Study
A 26-year-old woman with a single-ventricle circulation treated with the Fontan procedure wanted to become pregnant. She was advised by a multidisciplinary clinic including her adult congenital heart disease cardiology physician, the obstetrician, anesthetist, and midwife in the specialist referral center that this would be possible because she had good underlying cardiac function. She was taking warfarin anticoagulation therapy. A full anesthetic and obstetric management plan was made and put into her medical notes to communicate with the multidisciplinary team. The patient had good exercise tolerance with baseline observations of systemic arterial oxygen saturation of 94 percent on air, arterial blood pressure 110/70 mmHg, and heart rate of 90 beats/min in sinus rhythm.
She was seen again after conception and followed up regularly every 6 weeks in the joint clinic, having echocardiographic checks by her cardiology doctors and regular obstetric checks. Her normal warfarin was stopped to avoid embryopathy and substituted with a therapeutic dose of enoxaparin 40 mg SC twice a day.
She was well at 20 weeks’ gestation and continued her pregnancy with no signs of cardiac decompensation. At 35 weeks’ gestation, she was admitted to the specialist referral center for bed rest and more careful observation until 38 weeks, which is routine in cases such as this. At this point, delivery by induction of labor was planned. Enoxaparin anticoagulation was stopped 24 hours before induction to allow safe regional anesthesia and delivery. Because she had good cardiac function, induction of labor was planned with early low dose combined spinal epidural (CSE) analgesia. She was monitored with noninvasive blood pressure, ECG, and pulse oximetry. The baby was monitored with a cardiotocograph (CTG).
CSE anesthesia was performed with 1 ml hypobaric 0.25% bupivacaine and 25 µg fentanyl for the spinal component. Then 8-ml doses of 0.1% bupivacaine and 2 µg/ml fentanyl low-dose epidural mixture were given by patient-controlled epidural analgesia (PCEA) pump for the epidural component with a lockout time of 15 minutes. The analgesia worked well, and there was no need for any additional physician-administered rescue doses. The patient was carefully monitored throughout the day, and a decision was made not to place a radial artery catheter for invasive blood pressure monitoring because the patient was hemodynamically stable.
After a 9-hour labor that was augmented with oxytocin, the patient reached full cervical dilatation and was transferred to the operating room (OR) for an outlet forceps delivery to reduce the maternal effort of pushing. Her obstetricians were confident of a vaginal delivery.
In the OR, the epidural catheter was topped up in four divided doses of 5 ml low-dose bupivacaine 0.1% with 2 µg/ml fentanyl. The standard low-dose mixture was used for hemodynamic stability in the likelihood that delivery would be vaginal. If cesarean section were required, a higher concentration of local anesthetic (e.g., plain bupivacaine 0.5% or lidocaine 2% with epinephrine) would have been administered. An arterial line was inserted to accurately monitor blood pressure.
At delivery, there was a rapid vaginal blood loss of 500 ml. The patient felt faint, increased her heart rate to 110 beats/min, and became hypotensive with a blood pressure of 80/50 mm Hg. The blood loss was immediately replaced with 500 ml colloid solution IV, leading to an improvement in blood pressure and symptoms.
After delivery, the patient was given a low-dose oxytocin infusion (0.02 IU/ml at 36 ml/h) and restarted on a therapeutic dose of enoxaparin 40 mg twice daily SC (6 hours after epidural catheter removal). She spent 24 hours in the obstetric high-dependency unit under observation, after which time the arterial line was removed. Her warfarin was restarted. She went home after 3 days to be followed up in the multidisciplinary clinic and also at her specialist cardiac hospital. She and her baby were very well 1 year later.
Key Points
Complex patients with congenital heart disease (CHD) such as those with a double-outlet right ventricle, large ventricular septal defect, and pulmonary atresia treated with the Fontan repair may present to a specialist referral center antenatal clinic.
In such cases, comprehensive multidisciplinary planning and regular antenatal review may allow a smooth labor, timely regional anesthesia, and safe instrumental vaginal delivery with minimal hemodynamic compromise.
Discussion
Congenital heart disease (CHD) complicates 0.8 percent of all live births worldwide. In this century, more than 80 percent of neonates with moderate to complex CHD survive to adulthood, and over the last two decades, patients with complex congenital lesions are successfully completing pregnancies with careful planning and meticulous antenatal care. This is also true for patients with univentricular hearts and Fontan palliation. A comprehensive understanding of the individual patient’s cardiac anatomy, previous operations, and current physiology is crucial to successfully managing pregnancy and childbirth.
The normal cardiac configuration can be divided into seven features1:
1. The atrial situs (position) – situs solitus being normal with the left atrium on the left.
2. The draining pattern of the systemic and pulmonary veins.
3. The relationship between the atria and the ventricles. In the normal heart, this is a concordant relationship (i.e., the left atrium is connected to the left ventricle and the right to the right).
4. The absence of intracardiac defects – for example, an atrial septal defect (ASD) or a ventricular septal defect (VSD).
5. The status of the atrioventricular valves. These may be atretic (absent) or hypoplastic or draining into the wrong ventricle (i.e., blood that flows through the mitral valve drains into the right ventricle, instead of the left ventricle, and blood that flows through the tricuspid valve drains into the left ventricle, instead of the right ventricle).
6. The relationship between the ventricle and the great arteries (pulmonary and aorta). In the normal heart, there should be ventriculoarterial concordance (i.e., the ventricles are connected normally to the corresponding great arteries – left ventricle to the aorta and right ventricle to the pulmonary artery).
7. No extracardiac lesions such as patent ductus arteriosus (PDA) or coarctation of the aorta.
The patient was born with a large ventricular septal defect (VSD), a double-outlet right ventricle, and pulmonary atresia shown in Figure 16.1. This leads to mixing of oxygenated blood from the left atrium and deoxygenated blood from the right atrium in the ventricles. It also limits pulmonary blood flow due to pulmonary atresia. For this reason, the patient required bilateral Blalock-Taussig shunts as a baby. This shunt involves a conduit between the subclavian artery and the pulmonary artery. It helps to increase pulmonary blood flow – helping to improve oxygenation and growth of the pulmonary arteries. In this patient, the VSD was too large to permit a repair, which would result in a biventricular circulation, so her surgical team advised a Fontan repair with a fenestrated total cavopulmonary connection (TCPC) done in two stages. This results in anatomy with a “single ventricle,” or univentricular physiology, as shown in Figure 16.2 and in the MRI scan in Figure 16.3.
