Anästhesiologische Aspekte der Schwangerschaft und Entbindung bei einer Patientin nach modifizierter Fontan-Operation

The number of patients with congenital cyanotic heart disease who reach child-bearing age is increasing. This is partly a consquence of the high long-term survival and the haemodynamic benefits resulting from the Fontan procedure, which is used for the definitive palliation of such cyanotic heart disease as tricuspid atresia and single ventricle. However, so far little experience has been recorded with pregnant patients who have undergone right ventricular exclusion procedures. The particular physiology of a univentricular heart and a passive, non-pulsatile blood flow through the lungs has significant implications for the anaesthetic obstetric management of these patients. We report a case of successful pregnancy and caesarean delivery after a modified Fontan procedure. Case report. The patient was a 30-year-old pregnant woman with a singleton pregnancy. At the age of 20, after four palliative shunt operations, she had undergone a modified Fontan operation due to tricuspid atresia with a single ventricle, d-transposition of the great arteries, pulmonary atresia and a single atrium. Following the Fontan repair, 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. heparin preoperatively; for this reason, epidural anaesthesia was excluded, though it may otherwise be preferred for such patients. Amoxicilline was used to prevent endocarditis. At the date of caesarean delivery her body weight was 54?kg and boy height, 155?cm. Before induction of anaesthesia, a central venous and a radial artery catheter were placed for invasive pressure monitoring. An exaggerated left lateral tilt position was used to avoid aortocaval compression. After careful preoxygenation, anaesthesia 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 90?bpm. Delivery was accomplished 8?min after the induction of anaesthesia. The Apgar scores after 1 and 5?min were 9 and 10, respectively. Anaesthesia was continued with fentanyl, midazolam and nitrous oxide 50%. The remainder of surgery was unevenful. The child is now 5 years old and healthy. The mother has a near-normal activity level and does not need any help to care for her child. Discussion. After a modified Fontan repair, i.e. atriopulmonary or total cavopulmonary anastomosis, the pulsatile pulmonary blood flow is converted to a passive, non-pulsatile blood flow that depends critically both on the pressure gradient between right (RAP) and left atrial pressure (LAP) and on pulmonary vascular resistance (PVR). Thus, the maintenance of an adequate transpulmonary pressure gradient and avoidance of an increase in PVR are of major importance for the obstetric anaesthetic management in patients who have undergone right ventricular exclusion procedures. Impairment of venous return caused by slight caval compression or high airway pressure may reduce cardiac output more critically than in patients with a normal circulation. Conclusion. This case demonstrates that the haemodynamic consequences of pregnancy and of caesarean delivery under general anaesthesia can be tolerated in post-Fontan patients despite the absence of a contractile pulmonary ventricle.