Improved recovery of immature myocardium with L-glutamate blood cardioplegia.

Enhancement of myocardial recovery with glutamate-enriched cold blood potassium cardioplegia (BPC) was evaluated using an isolated working heart model. Three groups of hearts from immature rabbits were subjected to 20 minutes of warm (37 degrees C) ischemia to allow energy depletion, followed by 90 minutes of hypothermic (10 degrees C) ischemia. Myocardial protection provided during hypothermia consisted of cardioplegia infusion, at 50 mm Hg every 30 minutes at 4 degrees C, of either St. Thomas' Hospital solution (group 1, n = 6), oxygenated BPC (group 2, n = 7), or oxygenated BPC enriched with 20 mmol/L L-glutamate (group 3, n = 7). Percent recovery of aortic flow was 87.6% +/- 6.3% (results expressed as mean +/- standard error of the mean) in group 3, which was significantly better than for either group 1 (63.4% +/- 4.0%) or group 2 (47.0% +/- 3.5%) (p < 0.05 by analysis of variance). Group 3 hearts had significantly better recovery of myocardial energy stores (mumol/g dry weight) compared with group 1 or 2 hearts: adenosine triphosphate, 17.8 +/- 1.1 versus 12.4 +/- 1.5 and 12.1 +/- 0.4; creatine phosphate, 25.9 +/- 1.8 versus 17.8 +/- 1.8 and 20.3 +/- 0.7; and glycogen, 140.7 +/- 12.6 versus 98.7 +/- 9.9 and 60.7 +/- 9.9 (p < 0.05). Glutamate-enriched BPC provided excellent myocardial protection after ischemia in this immature model, and this study quantitatively supports the use of glutamate-enriched BPC in neonatal clinical practice.

End-to-end repair of aortic coarctation using absorbable polydioxanone suture.

Based on previous laboratory work, we have used polydioxanone absorbable suture in a variety of vascular and cardiac repairs in pediatric patients. However, some investigators have expressed concern about the potential for aneurysm formation at the anastomotic site. Between March 1983 and June 1989, 15 patients (7 male, 8 female) aged 2.5 months to 9.2 years (mean, 3.7 years) had resection of coarctation of the aorta and end-to-end anastomosis with polydioxanone absorbable suture. Thirteen patients have returned for routine postoperative evaluation, the follow-up time ranging from 11 to 49 months (mean, 23 months). Noninvasive two-dimensional, pulsed-wave Doppler and color echocardiography and magnetic resonance imaging studies demonstrated good anatomical repair and no anastomotic aneurysm formation or residual coarctation of the aorta in any patient after end-to-end anastomosis with polydioxanone. In summary, this intermediate follow-up study has revealed no vascular complications related to the repair of coarctation with absorbable polydioxanone suture.

Assessment of liver function during extracorporeal membrane oxygenation in the non-heart beating donor swine.

INTRODUCTION: Although the use of non-heart beating donors (NHBD) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to warm ischemia (WI), biliary tree injury, and inadequate organ assessment. Warm blood reperfusion using extracorporeal membrane oxygenation (ECMO) can be a suitable option to reduce WI in organs from NHBD, allowing one to determine hepatic flow characteristics and bile production and facilitating assessment of organ viability. METHODS: This work evaluates the use of warm blood veno-arterial ECMO reperfusion in NHBD swine. Systemic and hepatic hemodynamics, bile, urine, and mixed venous blood were measured. After baseline data collection, 10 kU heparin was given intravenously followed by 1 g KCl to elicit cardiac arrest (CA). ECMO was started after 30 or 60 minutes of CA and kept running for 120 minutes. RESULTS: One-way repeated measures analysis of variance (ANOVA) with Tukey test analysis was used within a group. Two-way ANOVA was used between groups. ECMO can restore venous SO2 and pH in both groups; the values were close to baseline in the 30-minute CA group. Also, in this group, bile production was > 65% from baseline early during reperfusion and its value was lower in the longer CA group < 55% (P < .001). Aspartate aminotransferase (AST) was doubled at the end of ECMO support in the 60-minute CA group (P < .05). CONCLUSION: In this preheparinized NHBD swine model, ECMO support restores liver perfusion, oxygenation, and bile production after 60 minutes of CA. Quantification and analysis of bile production could be a determinant of liver function during ECMO resuscitation, and it may be a predictor of graft viability before transplantation.

Successful surgical salvage of partial pancreatic allograft thrombosis.

BACKGROUND: Venous thrombosis remains an important cause of pancreatic graft loss. Nevertheless, reports are scarce of treatment alternatives to complete graft removal. We describe a case of surgical salvage of a partial pancreatic graft thrombosis. METHODS: We used descriptive retrospective analysis. RESULTS: A 36-year-old patient with juvenile-onset diabetes mellitus and previous living related renal transplant received a cadaveric pancreas transplant in the right iliac fossa with enteric exocrine drainage and standard vascular anastomosis. Two days after discharge from the hospital, he presented with severe right upper quadrant pain, nausea, vomiting, fever, and leukocytosis. He was taken to the operating room for exploration. The tail of the pancreas, which was kinked under the gallbladder, was necrotic and excised. The remainder of the pancreas looked normal. The patient recovered well from surgery and was discharged home 7 days later. CONCLUSIONS: Partial pancreatectomy is an acceptable surgical alternative for incomplete graft thrombosis.

Hemodynamic effects of a new right ventricular assist device.

A right ventricular assist device (VAD) based on the principle of counterpulsation has been developed at our institution. The device is a valveless, pneumatically actuated, 40 cc, sac-type pump, with a single inlet-outlet port. For right ventricular support, the "Uniport" pump is anastamosed end-to-side to the pulmonary artery. In previous experimental trials, the device has been shown to impart minimal trauma to blood components. In this study, biventricular failure was induced in eight Holstein calves by normothermic ischemia during cardiopulmonary bypass. A Pierce-Donachy left VAD (LVAD) was used for left ventricular support following the ischemic insult. Hemodynamic measurements were obtained throughout the study, and each animal served as its own control. A significant increase in post injury cardiac output (33.5 +/- 11.4%) was obtained with use of the Uniport and LVAD, as compared to use of the LVAD alone (p less than or equal to 0.005). Other hemodynamic parameters of right heart failure, including right atrial pressure (RAP), pulmonary artery pressure (PAP), and left atrial pressure (LAP) were not significantly affected. These data suggest that the Uniport right ventricular assist device significantly improves cardiac output in this model of moderate right ventricular failure. Additional studies are required, however, to optimize pump stroke volume, and to further define the performance envelope of the device.

A reconsideration of risk factors for the Fontan operation.

We reviewed our experience in 38 patients who underwent a Fontan operation. In the first five patients ages 7.5 to 23 years (mean, 15 years), a conduit was placed from the right atrium to the small right ventricle or the pulmonary artery (PA). The remaining 33 patients, ages 7 months to 14 years (mean, 4.8 years), had a modified Fontan operation with direct systemic venous or right atrial to PA anastomosis. The diagnoses were tricuspid atresia (n = 14), single ventricle (n = 10), hypoplastic right or left ventricle (n = 9), double-outlet right ventricle with inlet ventricular septal defect and pulmonary atresia or stenosis (n = 3), criss-cross ventricles and transposition of the great arteries (n = 1), and atrioventricular canal and anomalous pulmonary venous connection (n = 1). Thirty-two patients had previous surgery. Other procedures included PA banding (n = 7), systemic to PA shunts (n = 25), Norwood operation (n = 3), and a Damus-Kaye-Stansel anastomosis (n = 1), repair of total anomolous pulmonary venous connection (n = 1), a Blalock-Hanlon atrial septectomy (n = 1), and enlargement of a restrictive ventricular septal defect (n = 1). There were four operative deaths (10.5%), three from low cardiac output and one from subaortic obstruction. There were no deaths in patients younger than 3 years of age (n = 13). Subaortic obstruction developed in six of the seven patients who had pulmonary artery banding and resulted in three deaths. In our experience, diagnosis, previous surgery, type of previous operation, PA pressure, and younger age are not risk factors for early or late death. Subaortic obstruction is a major risk factor for late death. Accordingly we now perform a Damus-Kaye-Stansel anastomosis combined with a systemic to PA shunt in those children with excessive pulmonary blood flow who anatomically are likely to develop subaortic obstruction. A modified Fontan operation can be performed any time after 1 year of age and in some patients after 6 months of age, providing the anatomy and physiology of the patient are acceptable.