Unrecognized pulmonary venous desaturation early after Norwood palliation confounds Gp:Gs assessment and compromises oxygen delivery.

BACKGROUND: Hemodynamic stability after Norwood palliation often requires manipulation of pulmonary vascular resistance to alter the pulmonary-to-systemic blood flow ratio (Qp:Qs). Qp:Qs is often estimated from arterial saturation (SaO2), a practice based on 2 untested assumptions: constant systemic arteriovenous O2 difference and normal pulmonary venous saturation. METHODS AND RESULTS: In 12 patients early (

Staged operation to Fontan increases the incidence of sinoatrial node dysfunction.

Morbidity and mortality of total cavopulmonary connection (modified Fontan procedure) may be decreased in many patients with single ventricle in whom the risk of surgery is high by performing the operations in a staged fashion. Each operative intervention, however, exposes the sinoatrial node region to risk of injury, and a multistaged approach may increase the risk of altered sinoatrial node function in these patients. The purpose of this study was to compare the prevalence of perioperative arrhythmias in patients undergoing either a primary or staged approach to the Fontan operation. Records were retrospectively reviewed for all patients having a Fontan procedure between January 1988 and December 1992. Of 324 patients undergoing a Fontan operation, 227 had a Fontan operation without a prior cavopulmonary shunt (group 1) and 97 had a cavopulmonary shunt before a Fontan operation (group 2). Arrhythmias were classified as altered sinoatrial node function, supraventricular tachycardia, or atrioventricular block. The prevalence of both transient (resolving before hospital discharge) and fixed (persisting until hospital discharge) altered sinoatrial node function was similar for the two groups after cavopulmonary shunt or primary Fontan despite a heterogeneous patient population (group 1: 10.6%/4.4%; group 2: 10.3%/3.1%; p=0.28). Conversion from cavopulmonary shunt to Fontan in group 2 resulted in a higher prevalence of altered sinoatrial node function in the early postoperative period (transient: 23.7%; fixed: 23.7%; p < 0.001) and on follow-up (group 1: 7.7%; group 2: 16.7%; p < 0.02). In group 2, 40 of 82 patients without arrhythmia after first intervention (cavopulmonary shunt) had an arrhythmia after the second intervention (Fontan) (49%); of 14 with an arrhythmia after the first operation, 10 (71%) had one at the second intervention (p < 0.01). In conclusion, a multistaged operative pathway to Fontan reconstruction is associated with a higher early risk of altered sinoatrial node function. The occurrence of altered sinoatrial node function after cavopulmonary shunt is itself a risk factor for arrhythmia after the Fontan operation. Longer follow-up is needed to assess the full impact of this finding.

Anomalous pulmonary artery from the aorta via a patent ductus arteriosus: repair in a premature infant.

A successful repair of anomalous left pulmonary artery from the ascending aorta via a left ductus arteriosus in a 1 kg baby is reported. Repair was performed at an early age to avoid pulmonary hypertension and left pulmonary artery occlusion. Utilizing the right ductus to perfuse the right lung, surgery was performed without cardiopulmonary bypass.

Hyperoxia for management of acid-base status during deep hypothermia with circulatory arrest.

BACKGROUND: Which blood gas strategy to use during deep hypothermic circulatory arrest has not been resolved because of conflicting data regarding the advantage of pH-stat versus alpha-stat. Oxygen pressure field theory suggests that hyperoxia just before deep hypothermic circulatory arrest takes advantage of increased oxygen solubility and reduced oxygen consumption to load tissues with excess oxygen. The objective of this study was to determine whether prevention of tissue hypoxia with this strategy could attenuate ischemic and reperfusion injury. METHODS: Infants who had deep hypothermic circulatory arrest (n = 37) were compared retrospectively. Treatments were alpha-stat and normoxia (group I), alpha-stat and hyperoxia (group II), pH-stat and normoxia (group III), and pH-stat and hyperoxia (group IV). RESULTS: Both hyperoxia groups had less acidosis after deep hypothermic circulatory arrest than normoxia groups. Group IV had less acid generation during circulatory arrest and less base excess after arrest than groups I, II, or III (p < 0.05). Group IV produced only 25% as much acid during deep hypothermic circulatory arrest as the next closest group (group II). CONCLUSIONS: Hyperoxia before deep hypothermic circulatory arrest with alpha-stat or pH-stat strategy demonstrated advantages over normoxia. Furthermore, pH-stat strategy using hyperoxia provided superior venous blood gas values over any of the other groups after circulatory arrest.

Effect of modified ultrafiltration on plasma thromboxane B2, leukotriene B4, and endothelin-1 in infants undergoing cardiopulmonary bypass.

BACKGROUND: Plasma thromboxane B2 (TXB2), leukotriene B4 (LTB4), and endothelin-1 (ET-1) levels increase on cardiopulmonary bypass (CPB). Elevated levels of TXB2 and ET-1 have been correlated with postoperative pulmonary hypertension in infants undergoing repair of congenital heart defects. LTB4 is a potent chemotactic cytokine whose levels correlate with leukocyte-mediated injury. Modified ultrafiltration (MUF) has been associated with improved hemodynamics and pulmonary function, in addition to its beneficial effects on fluid balance and blood conservation. Recent investigations have suggested that removal of cytokines may be the cause of the improved cardiopulmonary function seen with MUF. METHODS: Plasma TXB2, ET-1, and LTB4 levels were measured in 34 infants undergoing CPB: 22 underwent MUF (group 1), and 12 did not (group 2). Samples were obtained at various time points. All patients underwent conventional ultrafiltration during the rewarming phase of cardiopulmonary bypass. RESULTS: In group 1, mean end-CPB TXB2 level was 101.2 pg/mL versus 46.9 pg/mL post-MUF (p < 0.05). The mean TXB2 level 1 hour post-CPB (54.1 pg/mL) was not significantly different from the post-MUF level. In group 2, the mean end-CPB TXB2 level was 123.6 pg/mL versus 53.2 pg/mL 1 hour post-CPB. Hence, TXB2 levels decreased by similar amounts and to similar levels by 1 hour post-CPB in both groups. ET-1 levels increased after CPB and were unaffected by MUF: 1.45, 1.80, 2.55 pg/mL at end-CPB, post-MUF, and 1 hour post-CPB, respectively, in group 1; and 1.51, and 2.73 pg/mL at end-CPB and 1 hour post-CPB in group 2. LTB4 levels post-MUF were 119% of pre-MUF values, and were similar at 1 hour post-CPB in both groups. CONCLUSIONS: Despite reduction in TXB2 by MUF, values were similar and approached baseline 1 hour post-CPB in both groups. LTB4 levels increased slightly with MUF. ET-1 levels increased during and post-CPB and were unaffected by MUF. MUF does not appear to have a significant effect on post-CPB levels of TXB2, ET-1, and LTB4. Therefore, the improved hemodynamics observed with MUF do not appear to be related to removal of these cytokines.

Congenital diaphragmatic hernia presenting due to gastrointestinal complications.

Congenital diaphragmatic hernia (CDH) presents beyond the first hours of life in 10% to 20% of cases. Presenting symptoms may be quite nonspecific, and are often gastrointestinal rather than respiratory in origin. We have recently had experience with five such cases, one in a newborn and four in older children. All presented with symptoms related to gastrointestinal complications of their diaphragmatic defect. In the newborn, gastric perforation had occurred, a complication of this anomaly not previously reported. The chest radiograph showed loops of bowel in the chest in all cases, allowing correct preoperative diagnoses. Urgent operative intervention was undertaken in each case with good results and no long-term morbidity. The risk of intestinal strangulation in the late-presenting CDH patient warrants emergent surgical management, which should be rewarded by uniform survival with few complications. Although preoperative stabilization may decrease the severity of pulmonary vasospasm in the newborn with respiratory failure, delay may increase the risk of bowel infarction in the older child presenting with gastrointestinal symptoms.

Comparison of muscle-sparing thoracotomy and thoracoscopic ligation for the treatment of patent ductus arteriosus.

PURPOSE: We reviewed our experience with the treatment of patent ductus arteriosus (PDA), and compared two therapeutic techniques; muscle-sparing thoracotomy (MST) and thoracoscopic PDA ligation (TPDAL). METHODS: We reviewed the clinical records and operative reports of 19 nonnewborn patients who were treated at our institution for PDA. Eleven patients underwent TPDAL and eight patients MST. The TPDAL patients underwent thoracoscopic clipping (ligation) of the PDA, whereas the MST group had a complete division of the ductus. A two-tailed Student's t test was used to calculate the 95% confidence intervals for length of operation, number of doses of intravenous narcotics and hospital stay. Costs were also compared. RESULTS: All patients underwent diagnostic echocardiography in the evaluation of an asymptomatic murmur. Both groups were similar in age (average, 4 years) and gender. All procedures were performed electively. Two thoracoscopic attempts were aborted, one for bleeding and the other for inadequate clip size. The length of the procedure averaged 1.3 hours +/- 0.330 SD for TPDAL versus 1.4 hours +/- 0.335 SD for MST. Five of the nine successful TPDAL patients were admitted to the Pediatric Intensive Care Unit (PICU) with an average length of stay of 20 hours, and two of eight MST patients stayed in the PICU for average of 18 hours. All patients were extubated after the procedure. Chest tubes were placed in two TPDAL patients and three MST patients. However, two patients who underwent TPDAL required tube thoracostomy for persistent postoperative pneumothorax. Average number of intravenous narcotics administered for the TPDAL was 1.2 doses per patient and for MST, 1.75 doses per patient. Mean hospital stay for TPDAL was 1.33 +/- 0.71 SD days and for MST 1.8 +/- 0.83 SD days. Ninety-five percent (95%) confidence intervals for the difference in means demonstrated no difference between the two groups for length of operation, hospital stay, or number of doses of intravenous narcotics administered. CONCLUSIONS: The authors were unable to identify any benefit to thoracoscopic patent ductus arteriosus ligation versus muscle-sparing thoracotomy in terms of hospital stay, length of operation, or morbidity. Additionally, with MST there is a complete division of the PDA theoretically decreasing the risk of recurrence in comparison with clip ligation.

Alternative methods for anticoagulation monitoring in pediatric patients with applicability to a patient with severe hemophilia A and circulating inhibitor.

Anticoagulation monitoring in pediatric patients can be problematic because of the immaturity of the coagulation system in this population. In addition, the hemodilution required to place a small patient on bypass can interfere with standard monitoring methods. In this institution, the Hemochron Jr. ACT (activated clotting time)+ assay has been the standard of care for anticoagulation monitoring since 1997. This assay, with a target ACT of 400 s for initiating bypass, was compared to both the Medtronic HMS system (N = 7) and the Hemochron HiTT assay (N = 6) in pediatric patients. All three assays were then employed to monitor a pediatric Hemophilia A patient (Factor VIII <1%) with high inhibitor titer. Both the HiTT clotting time and the HMS heparin level showed statistically significant correlation to the ACT+ (HiTT, N = 24, r = 0.761; HMS, N = 31, r = 0.818). An HMS target heparin level of 1.5 mg/kg and a HiTT target clotting time of 180 s were found to be clinically equivalent to the 400-s ACT+ as indicators of the need for additional heparin. When a 7-year-old male with severe hemophilia A and high inhibitor titer required tricuspid valve replacement, all three assays were used to ensure appropriate anticoagulation management. During bypass, this patient's ACT+ remained out of range (>1005 s). The HiTT was maintained at >180 s and the HMS heparin level at >1.5 mg/kg. Heparin was administered when any single parameter was below the cutoff value. The use of the combination of three distinct monitoring assays for this patient allowed the surgical team an added level of confidence that appropriate anticoagulation had been maintained.

Bilateral phrenic nerve palsy associated with benign thyroid goiter.

Phrenic nerve palsy secondary to benign thyroid enlargement is a previously unreported complication. Large goiters, particularly substernal, may impinge upon adjacent structures, often leading to significant symptoms such as dysphagia or dyspnea due to airway compression. The phrenic nerve may be stretched by a large goiter along its course in the neck, but the more likely site of injury is the point at which it enters the thoracic cavity adjacent to the first rib. Such an injury, caused by compression, may go unrecognized if unilateral, as symptoms would be uncommon. However, bilateral phrenic nerve palsy can cause significant dyspnea due to pulmonary insufficiency, particularly in an elderly patient with cardio-pulmonary disease. Early operative treatment of the goiter may prevent this complication or limit its severity, thus avoiding permanent nerve injury.

Experience with the straight endorectal pullthrough for the management of ulcerative colitis and familial polyposis in children and adults.

The first significant experience with the straight endorectal pullthrough for the management of ulcerative colitis was presented before the American Surgical Association in 1977 by Lester Martin. Since then the operation with or without modification has been used extensively. High stool frequencies in some series led to disenchantment with the straight anastomosis and to the development of various reservoir procedures to increase rectal capacity and thereby reduce frequency. As a result, no large series of straight pullthroughs is available for comparison with the reservoir modifications. Between September 1977 and September 1986, 72 children and adults, 61 with ulcerative colitis and 11 with familial polyposis, underwent endorectal pullthrough (ERPT) and straight ileoanal anastomosis under the overall direction of a single surgeon (AGC). Sixty patients have undergone ileostomy closure and form the basis of this study. Mean age at operation was 22.7 years (range 4-48 yr), and duration of active disease averaged 6 years. One-half of the patients underwent total abdominal colectomy with ERPT as a primary procedure. There were 11 cases of adhesive bowel obstruction following ERPT, and in six patients in the series permanent revision to a Brooke ileostomy was required. One patient died of hepatic failure in the late postoperative period. Follow-up has ranged from 3 months to 9 years. Mean stool frequency for the group as a whole at 3, 6, 12, 24, and 36 months was 11.8, 11.2, 9.6, 9.0, and 8.3 per 24 hours, respectively. Daytime continence was achieved in all patients. Occasional nocturnal soiling occurred in 11.1% of patients at 1 year. Stool frequency and continence were also analyzed by age group above and below 18 years and above and below 30 years. There were no statistically significant differences between these groups. The authors conclude from this study that ERPT with straight ileoanal anastomosis remains an appropriate alternative for children and adults with ulcerative colitis or familial polyposis and compares favorably with the more complicated ERPT involving a reservoir.

Fifty years' experience with esophageal atresia and tracheoesophageal fistula. Beginning with Cameron Haight's first operation in 1935.

Four hundred twenty-six patients with esophageal atresia with or without tracheoesophageal fistula have been primarily cared for at the University of Michigan Medical Center since Cameron Haight's initial experience with this entity. Over the period of observation, the incidence of new cases as well as the number of associated anomalies has remained constant. The long-term survival of these patients has steadily improved over the past half-century from 36% in the pre-1950 era to 84% during the most recent 20 years. Conversely, operative mortality has shown a progressive decline from 56% early in the authors' series to 6.9% more recently, despite a steady increase in the proportion of high-risk neonates seen at the University of Michigan Medical Center during this time span. In the last 9 years, there have been no postoperative deaths in group A or B risk infants (36 patients), while the rate has been 18.2% in group C risk babies (27 patients); almost all of these deaths were due to severe associated anomalies. During the last 10 years, the authors have changed their technique of anastomosis from a two- to a one-layer method while still advocating a primary repair via an extrapleural approach. Although this change has resulted in a modest increase in the rate of anastomotic leak (17% vs. 6.2%, p less than 0.03), the leaks have been small and asymptomatic because of the extrapleural approach and, as a result, have been managed conservatively without any untoward sequelae. Conversely, there has been a significant decrease in the rate of stricture formation with the one-layer anastomosis (4.3% vs. 23.3%, p less than 0.002). While this may in part be explained by the change in anastomotic technique, it is felt that the more aggressive diagnosis and surgical management of gastroesophageal reflux (seen in 37.9% of our recent group) have contributed greatly to this decrease. The steady improvement in survival over this 50-year period, in spite of the increasing number of high-risk infants, is attributable to major improvements in neonatal care before, during, and after operation.

Unique features and prognosis of primum ASD presenting in the first year of life.

BACKGROUND: Primum atrial septal defect (ASD) is a defect that is usually associated with few symptoms and can be electively repaired with good results. A review of our experience with primum ASD identified a subset of patients characterized by presentation with congestive heart failure (CHF) in the first months of life and a requirement for early operation. Echocardiograms, catheterizations, operative reports, and clinical data were reviewed and compared with that on all other patients with primum ASD. Patients with transitional or complete atrioventricular (AV) canal defects were excluded. METHODS AND RESULTS: From January 1984 to December 1992, significant CHF was present in the first year of life in 11 patients (10.5%) with primum ASD who were managed surgically among 105 total patients undergoing repair of primum ASD. This early CHF group had a higher incidence of hypoplastic left-sided cardiac structures (9 of 11 patients) compared with other primum ASD patients (5 of 94, P < .001), including patients with coarctation (CoA) (n = 9), abnormal mitral valve (n = 7), left ventricular hypoplasia (n = 5), and subaortic stenosis (subAS) (n = 7). Other differentiators from patients without early CHF included incidence of Downs syndrome (0% versus 19%), elevated pulmonary artery pressures (72% versus 33% systemic, P < .001), earlier mean age at operation (8 months versus 5.4 years), greater incidence of reoperation after initial ASD closure (5 of 8 patients, 12 operations [5 subAS, 3 mitral valve, 3 CoA, 1 pacemaker] versus 4 of 93 patients, P < .001), and higher mortality (36% versus 1%, P < .001). CONCLUSIONS: Left-sided obstructive lesions must be sought in children with primum ASD presenting with CHF in the first year of life. The presence of these lesions alters prognosis and surgical management and mandates close follow-up, with particular attention to late appearance or progression of subaortic stenosis or deterioration of mitral valve function.

Oxygen free radical activity during live E. coli septic shock in the dog.

Free radicals generated during purine catabolism or by activated granulocytes cause tissue injury by peroxidation of lipid membranes. In a canine model of sepsis initiated by intravenous live Escherichia coli, fluorescent products of lipid peroxidation (FP) were measured in serum. Four groups of five dogs infused with 10(9)E. coli/kg were analyzed--I: no further treatment; II: prior depletion of granulocytes with a cytotoxic antibody; III: pre-treatment with superoxide dismutase and catalase; and IV: resuscitation after bacterial infusion to maintain cardiac output greater than 80% of pre-bacteremic levels. In Groups I, II, and III, cardiac output fell to less than 50% of baseline within 1 hr and remained there throughout the study. FP in Groups I and II rose to greater than 200% of baseline (P less than .02 and less than .03). In Groups III and IV, FP did not rise significantly from baseline. The rise in serum FP and the prevention of this rise by-treatment with antioxidants indicate generation of oxygen radicals. Their presence had no effect on hemodynamic parameters. Granulocyte depletion did not alter appearance of FP; however, prevention of low cardiac output blocked FP formation. These data suggest that oxygen free radicals were generated by tissue ischemia, rather than by granulocytes, in this model of septic shock.

Cost-effectiveness of coarctation repair strategies: endovascular stenting versus surgery.

The cost-effectiveness of stent (ST) implantation for the repair of coarctation of the aorta (CoA) is not documented in the medical literature. Inflation-adjusted hospital costs for ST implantation and for surgical (SU) repair were obtained using the HBOC Cost Accounting System software and evaluated for all patients 5 years of age or older who underwent elective treatment of CoA between July 1997 and June 2001. The average age of the ST group (n = 10) to 9.5 +/- 3.5 years for the SU group (n = 12) (p > 0.10). The ST group had one failure due to inability to cross the CoA (failure rate, 10%). Successful repair was accomplished in all other ST cases and in all SU cases, with no residual systolic gradients at 1-year follow-up. Hospital length of stay for the ST group was 0.8 +/- 1.2 days compared to 3.5 +/- 0.5 days for the SU group (p < 0.001). The mean inflation-adjusted cost for the ST group was dollar 7,148 +/- 2,984 versus dollar 11,769 +/- 3,702 for the SU group (p < 0.005). By intention to treat analysis, the cost of repair in the ST-first group was dollar 8,325 +/- 3,354 given the 10% failure rate (p < 0.04 vs the SU only group). Sensitivity analysis demonstrates that cost of repair is lower with the ST-first strategy compared to SU only until the failure rate of ST implantation exceeds 39%. Repair of CoA using an endovascular stent strategy is cost-effective compared to conventional surgical repair.