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Departments of
*Anesthesiology,
Pediatrics,
Surgery, and
§Intensive Care, Catholic University of Louvain, Cliniques Universitaires Saint-Luc, Brussels, Belgium
Address correspondence and reprint requests to Luc Van Obbergh, MD, PhD, Department of Anesthesiology, Cliniques Universitaires Saint-Luc, 10 1821 Avenue Hippocrate, 1200 Brussels, Belgium.
| Abstract |
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Implications: Some children with Alagilles syndrome require liver transplantation. In our study, associated pulmonary artery stenosis did not dramatically increase perioperative risk. Veno-venous bypass decreased intraoperative hemodynamic changes in these patients.
| Introduction |
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| Methods |
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| Results |
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All prothrombin times and initial hemoglobin were normal (mean 10.4 ± 1.4 g/L). By ultrasonography, ascites was detected in one child and portal hypertension in three children.
Pulmonary artery stenosis was demonstrated either by echocardiography or cardiac catheterization in all patients. Associated cardiopulmonary abnormalities were pulmonary artery hypoplasia in two patients (Patients 1 and 10) and ventricular septal defect in one (Patient 5). The severity of pulmonary artery stenosis varied from mild to severe. Right ventricular pressure was increased in 11 children. Balloon angioplasty was performed on three of the children (Patients 10, 14, and 15) before OLT; two cases (Patients 14 and 15) were minimally successful in partially relieving stenosis in the pulmonary artery. Pulmonary artery stenosis did not result in hypoxemia, and peripheral arterial saturation was normal in all children (mean 99 ± 1%).
Intraoperative Variables
Twenty-one OLT procedures were performed on 16 patients. All the cases had central venous pressure monitoring, whereas 14 subjects also had pulmonary artery pressure monitoring.
Thirteen cases were induced with either halothane or sevoflurane and intubated with pancuronium. Five underwent IV induction with etomidate, four as part of rapid sequence induction with suxamethonium. Analgesia was provided with fentanyl or sufentanil. Three cases arrived previously intubated from the ICU for urgent retransplantation. All patients were hemodynamically stable at induction.
Mean duration of anesthesia was 519 ± 17 min, with the anhepatic phase lasting 83 ± 24 min on average. Mean perioperative blood transfusion was 156.7 ± 127 mL/kg (range 0532.9 mL/kg). Hourly urine output was 2.7 ± 1.9 mL · kg-1 · h-1 (range 0.46.5 mL · kg-1 · h-1). At caval clamping, systolic blood pressure (SBP) decreased by a mean of 15 ± 9 mm Hg, with concomitant decreases in mean pulmonary artery pressures (5 ± 3 mm Hg) and central venous pressures (4 ± 3 mm Hg). Caval unclamping resulted in a further decrease in SBP (16 ± 13 mm Hg), but was accompanied by increases in mean pulmonary artery (3 ± 4 mm Hg) and central venous pressures (1 ± 4 mm Hg). When those cases done without bypass were divided into two groups based on right ventricular (RV) systolic pressures (severe RV > 50 mm Hg, less severe RV < 50 mm Hg), there were no great differences in hemodynamic changes between them (16 ± 4 vs 18 ± 19 mm Hg decrease in SBP at clamping; 21 ± 17 vs 16 ± 12 mm Hg decrease in SBP at unclamping). The intraoperative hemodynamic variables are described in Table 1. Veno-venous bypass was used during the anhepatic phase in 4 of the 21 transplants. The decision to use veno-venous bypass was made prior to the operations on the basis of the severity of pulmonary stenosis and consequent increased RV pressures. The left axillary vein was used in two cases. In the other two cases, the axillary vein was too small and a 16G IV cannula inserted in the internal jugular vein by the anesthetist was used for bypass instead. These four cases had smaller declines in pressure at clamping, compared with cases without bypass (5 ± 7 mm Hg vs 17 ± 14 mm Hg). Differences between the two groups at unclamping were less impressive (14 ± 13 mm Hg vs 17 ± 7 mm Hg). We were unable to disclose any relation between the gradient measured across pulmonary stenosis as shown in Table 1 and the systolic variation occurring at clamping (linear regression R = 0.46, P = 0.034) or at unclamping (linear regression R = 0.14, P = 0.54). Of the four cases using bypass, three were uneventful hemodynamically, but one had a transient episode of bradycardia and hypotension at unclamping of the portal vein. In the remaining 17 OLTs (no bypass), 15 were hemodynamically stable intraoperatively; also, there was one case with transient bradycardia associated with hypotension, and 1 case remained persistently hypotensive after unclamping requiring epinephrine and norepinephrine infusions. Surgically, total cross-clamping of the inferior vena cava was performed in eight cases. The piggyback technique (6) with caval lateral clamping was performed in the other 13 cases. All cases received small-dose dopamine (25 µg · kg-1 · min-1) during the anhepatic and reperfusion phases of the operation. Isoproterenol at low concentrations (0.010.02 µg · kg-1 · min-1) was infused for a short time in three of the cases in response to mild bradycardia (6085/min) not associated with hypotension. At no time during the operation was there any significant decrease in pulse oximetry values.
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Three cases (OLTs 2, 4, and 6) died, not due to cardiovascular complications, in the postoperative period. Discharge from the ICU was also not delayed by cardiovascular problems and was accomplished within 5 days in 10 of the 18 cases that did not require early retransplantation. Two others children died 6 and 9 mo after OLT.
| Discussion |
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In our set of patients, liver cirrhosis as an indication accounted for only 19% (3 of 16) of all first OLTs; the remaining patients (81%) were transplanted because of severe limitation in the quality of life. Preoperative administration of clotting factors was not required, because protein synthesis is maintained with normal or near-normal serum protein levels and coagulation profiles (2). Patients with Alagilles syndrome have greatly increased cholesterol, triglyceride, and low-density lipoprotein-cholesterol levels, together with decreased high-density lipo-protein-cholesterol levels (7). All of our children had increased serum cholesterol, whereas nine (56%) of them had xanthomas. However, the cardiovascular implications of this abnormal lipoprotein profile in patients with Alagilles syndrome have still not been fully studied.
The average time from diagnosis to OLT in our series was 4 yr and 10 mo. The slow deteriorating course of these patients allows time for full cardiovascular evaluation before transplantation (3,8). There are associated cardiac abnormalities in approximately 85% of patients with Alagilles syndrome (3) (100% of the patients in our study). The most common anomaly is stenosis in the peripheral pulmonary arterial tree or in either or both of the main pulmonary arteries. Stenosis appears to be nonprogressive,1and echocardiography repeated over several years on some of our patients showed stable degrees of pulmonary artery stenosis over time. Pulmonary vascular hypoplasia and/or intracardiac defects have also been reported either in isolation or in association with peripheral pulmonary stenosis (5). Reports on mortality rates in Alagilles syndrome attributed to cardiopulmonary complications indicate rates ~10% (3,9,10). In cases with pulmonary vessel stenosis, RV hypertrophy is a common finding (11), but cardiac function is usually well preserved (2). Balloon angioplasty of the stenosis may be considered, especially for the more severe cases. However, this procedure is not without risk (12), and of the three patients on whom angioplasty was performed, two had only slight improvement whereas one had none. Nevertheless, OLT was performed successfully albeit with veno-venous bypass in two of these patients.
We encountered no hemodynamic problems during induction. Hemodynamic instability prior to the anhepatic phase is usually due to surgical blood loss from hepatic dissection. Although 75% of our children had previous abdominal surgery, we experienced no excessive bleeding during this phase. Apart from possibly massive and often rapid blood loss during OLT, other causes of intraoperative hemodynamic changes are clamping and unclamping of the inferior vena cava and portal vein, and various factors at reperfusion of the new liver, resulting in myocardial depression and vasodilatation. The periods of clamping and unclamping resulted in a significantly greater decrease in blood pressure, compared with that experienced in our average pediatric population undergoing OLT, despite relatively similar changes in central venous and pulmonary artery pressures (13). These decreases in blood pressure were transient and responded to fluid loading. The probable explanation is an increased dependency in these patients on preload to maintain RV ejection (14). However, no differences were found between "severe" (RV > 50 mm Hg) and "less severe" (RV < 50 mm Hg) cases, and there was no correlation between severity of pulmonary stenosis and intraoperative hemodynamic changes. The importance of optimization of preload in these patients is set in the scenario of preexisting vasodilatation and increased cardiac output secondary to liver disease. A decrease in RV preload may lead to a vicious cycle of decreased RV output, inadequate left ventricular preload and output, and decreased systemic blood pressure. Because RV hypertrophy, and therefore an increased susceptibility to RV myocardial ischemia, is common in these patients, an excessive decrease in systemic blood pressure should be avoided. In our institution, we accept a 30% decrease in blood pressure at clamping, beyond which (after judicious fluid loading) we tend toward the use of veno-venous bypass. We use central venous pressures as a guide to optimize preload, and thus RV contractility, and find pulmonary artery pressures measured via a pulmonary artery catheter to be less useful as an indication of RV function, because the catheter tip is often beyond stenosis in the pulmonary artery. However, central venous pressure is a less reliable indicator of RV preload in patients undergoing OLT (15). Thus, transesophageal echography would be useful in this setting to aid in optimizing right heart performance (16). In four (two children) of the more severe cases (RV 98 mm Hg, 60 mm Hg), veno-venous bypass was used resulting in smaller blood pressure changes especially at clamping. This observation is also probably related to the maintenance of adequate venous return during this critical period. Contrary to theoretical expectations, we found no differences in blood pressure changes at clamping between cases where the piggyback technique was used and those requiring total clamping of the inferior vena cava. However, our sample sizes are too small to draw any conclusions.
Postoperatively, most patients had no hemodynamic problems and no delay in extubation or discharge from intensive care attributable directly to Alagilles syndrome. The incidence of retransplantation in our group of patients (31%) was higher than that expected from a contemporaneous non-Alagilles population (17), but similar to other studies in this population (9). We could not account for this increased incidence.
In summary, patients with Alagilles syndrome cope well with the major hemodynamic changes during OLT. Careful attention to ensuring adequate preload of the right ventricle is important, especially in these patients. The immediate postoperative cardiovascular and respiratory course is not affected by the disease. We are unable to determine a threshold (if one exists) in severity of pulmonary artery stenosis, whereby OLT would be contraindicated. However, in severe cases of pulmonary artery stenosis, veno-venous bypass, although not mandatory, is useful in minimizing potential changes in blood pressure during caval clamping and unclamping.
| Footnotes |
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| References |
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