PREGNANCY AND DELIVERY AFTER MATERNAL FON TAN REPAIR

The number of patients with congenital cyanotic heart disease who reac h child-bearing age is increasing. This is partly a consquence of the high long-term survival and the haemodynamic benefits resulting from t he Fontan procedure, which is used for the definitive palliation of su ch cyanotic heart disease as tricuspid atresia and single ventricle. H owever, so far little experience has been recorded with pregnant patie nts who have undergone right ventricular exclusion procedures. The par ticular physiology of a univentricular heart and a passive, non-pulsat ile blood flow through the lungs has significant implications for the anaesthetic obstetric management of these patients. We report a case o f successful pregnancy and caesarean delivery after a modified Fontan procedure.Case report. The patient was a 30-year-old pregnant woman wi th a singleton pregnancy. At the age of 20, after four palliative shun t operations, she had undergone a modified Fontan operation due to tri cuspid atresia with a single ventricle, d-transposition of the great a rteries, pulmonary atresia and a single atrium. Following the Fontan r epair, she initially suffered from intermittent Wolff-Parkinson-White syndrome and isorhythmic AV dissociation. The pregnancy was uneventful , and caesarean section was scheduled for 32 weeks' gestation. Because of the increased risk of thrombosis, the patient was treated with s.c . preoperatively; for this epidural anaesthesia was excluded, though i t may otherwise be preferred for such patients. Amoxicilline was used to prevent endocarditis. At the date of caesarean delivery her body we ight was 54 kg and boy height, 155 cm. Before induction of anaesthesia , a central venous and a radial artery catheter were placed for invasi ve pressure monitoring. An exaggerated left lateral tilt position was used to avoid aortocaval compression. After careful preoxygenation, an aesthesia was induced with 24 mg etomidate, 1.5 mg norcuronium, and 75 mg succinylcholine. Halothane 0.5-0.7% in oxygen was used during the first few minutes of surgery. Central venous pressure under mechanical ventilation was 20 mmHg, while the heart rate varied between 70 and 9 0 bpm. Delivery was accomplished 8 min after the induction of anaesthe sia. The Apgar scores after 1 and 5 min were 9 and 10, respectively. A naesthesia was continued with fentanyl, midazolam and nitrous oxide 50 %. The remainder of surgery was unevenful. The child is now 5 years ol d and healthy. The mother has a near-normal activity level and does no t need any help to care for her child. Discussion. After a modified Fo ntan repair, i.e. atriopulmonary or total cavopulmonary anastomosis, t he pulsatile pulmonary blood flow is converted to a passive, non-pulsa tile blood flow that depends critically both on the pressure gradient between right (RAP) and left atrial pressure (LAP) and on pulmonary va scular resistance (PVR). Thus, the maintenance of an adequate trans-pu lmonary pressure gradient and avoidance of an increase in PVR are of m ajor importance for the obstetric anaesthetic management in patients w ho have undergone right ventricular exclusion procedures. Impairment o f venous return caused by slight caval compression or high airway pres sure may reduce cardiac output more critically than in patients with a normal circulation. Conclusion. This case demonstrates that the haemo dynamic consequences of pregnancy and of caesarean delivery under gene ral anaesthesia can be tolerated in post-Fontan patients despite the a bsence of a contractile pulmonary ventricle.