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Biomedical subjects

R D Mainwaring

Publications and source records attributed to R D Mainwaring.

At least 19 recordsLinked to original sources
PubMed2001

Reduction in levels of triiodothyronine following the first stage of the Norwood reconstruction for hypoplastic left heart syndrome.

OBJECTIVE: Thyroid hormone has important effects on cardiovascular performance. This study was performed to evaluate the changes in levels of triiodothyronine following the first stage of reconstruction for hypoplastic left heart syndrome. METHODS: We enrolled 14 newborns with hypoplastic left heart syndrome scheduled for first stage reconstruction. Blood samples were obtained pre-, intra-, and post-operatively. Levels of free and total triiodothyronine were determined by radioimmunoassay. Statistical comparison was performed using Wilcoxon's signed rank test. RESULTS: The levels of free triiodothyronine decreased from a baseline of 355+/-31 pg/dl to 205+/-21 pg/dl upon the institution of bypass, and declined to a level of 135+/-9 pg/dl at 24 hours postoperatively. Similarly, levels of total triiodothyronine decreased from 101+/-15 ng/dl to 65+/-4 ng/dl upon the institution of bypass, and continued to decline during the first 24 hours postoperatively. Levels of free and total triiodothyronine had returned to baseline by the fifth postoperative day. CONCLUSIONS: The data demonstrate significant decreases in levels of free and total triiodothyronine during the early postoperative period. These changes in levels of thyroid hormone may have adverse effects on cardiac function during this phase of recovery.

Adult↗
PubMed2000

Pharmacokinetic evaluation of triiodothyronine supplementation in children after modified Fontan procedure.

BACKGROUND: Triiodothyronine (T(3)) supplementation may be a useful adjunct in the management of patients after cardiopulmonary bypass. Limited data are available regarding the use and pharmacokinetics of T(3) in children. The present study was performed to evaluate T(3) pharmacokinetics in a cohort of children undergoing the modified Fontan procedure. METHODS AND RESULTS: A total of 28 patients were enrolled in this randomized, prospective study. The patients were divided into 4 groups: 1 group received a placebo and 3 groups received intravenous T(3) at dosages of 0.4, 0.6, and 0.8 microg/kg, respectively. All 28 patients survived their operative procedures. Two patients developed low cardiac output, and 3 patients had pleural effusions. The median length of hospital stay was 7 days. The mean free T(3) level was 316+/-67 pg/dL after then administration of a placebo. Patients who received T(3) had mean peak free T(3) levels of 972+/-88, 1351+/-299, and 1869+/-281 pg/dL for the dosages of 0.4, 0.6, and 0.8 microg/kg, respectively. The calculated half-life of T(3) was 7 hours. CONCLUSIONS: The half-life of intravenous T(3) in children is approximately one-third of that reported for adults. These results provide a framework for studying the efficacy of T(3) supplementation in children undergoing open-heart surgery.

Cardiac Output↗
PubMed2000

Shoulder pain in a child: a case presentation of ganglioneuroblastoma.

A four and one-half year-old child presented with a several month history of shoulder pain. Her workup revealed a large, homogeneous tumor in the apex of the chest. Surgical resection was performed demonstrating ganglioneuroblastoma. This case illustrates an unusual cause of joint discomfort in children.

Child, Preschool↗
PubMed1999

Effect of accessory pulmonary blood flow on survival after the bidirectional Glenn procedure.

BACKGROUND: The bidirectional Glenn procedure (BDG) is used in the staged surgical management of patients with a functional single ventricle. Controversy exists regarding whether accessory pulmonary blood flow (APBF) should be left at the time of BDG to augment systemic saturation or be eliminated to reduce volume load of the ventricle. The present study was a retrospective review of patients undergoing BDG that was conducted to assess the influence of APBF on survival rates. METHODS AND RESULTS: From 1986 through 1998, 149 patients have undergone BDG at our institution. Ninety-three patients had elimination of all sources of APBF, whereas 56 patients had either a shunt or a patent right ventricular outflow tract intentionally left in place to augment the pulmonary blood flow provided by the BDG. The operative mortality rate was 2.2% without APBF and 5.4% with APBF. The late mortality rate was 4.4% without APBF and 15.1% with APBF. Actuarial analysis demonstrates a divergence of the Kaplan-Meier curves in favor of patients in whom APBF was eliminated (P<0.02). One hundred seven patients have subsequently undergone completion of their Fontan operation, so the actuarial analysis includes the operative risk of this second operation. CONCLUSIONS: The results suggest that the elimination of APBF at the time of BDG may confer a long-term advantage for patients with a functional single ventricle.

Fontan Procedure↗
PubMed1998

Complement activation and cytokine generation after modified Fontan procedure.

BACKGROUND: The modified Fontan procedure separates the systemic and pulmonary circulations in patients born with a functional single ventricle. Delayed recovery is frequently observed after this procedure. It was our hypothesis that complement activation or cytokine generation may contribute to the pathophysiology of this problem. METHODS: We measured activated complement C3, thromboxane B2, interleukin-6, and tumor necrosis factor-alpha levels by immunoassay in 16 patients undergoing Fontan procedure. Patient plasma samples were obtained preoperatively, on initiation of cardiopulmonary bypass, after administration of protamine, and 1, 4, 8, and 24 hours postoperatively. RESULTS: There was no early or late mortality in this cohort of patients. Low cardiac output developed in 3 of 16 patients, and pleural effusions developed in 5. The median length of hospital stay was 9 days. Activated complement C3 levels increased from a baseline of 1,486 +/- 564 to 4,600 +/- 454 ng/mL after cardiopulmonary bypass and administration of protamine, and returned to baseline by 24 hours. The level of interleukin-6 increased from 42 +/- 32 to 176 +/- 22 pg/mL and at 24 hours remained elevated at 71 +/- 15 pg/mL. Neither thromboxane B2 nor tumor necrosis factor-alpha levels increased significantly. CONCLUSIONS: The data demonstrate threefold to four-fold increases in activated complement C3 and interleukin-6, indicating that both humoral and cellular systems are affected. It is our conclusion that complement and cytokine activation may contribute to the delayed recovery observed after Fontan procedure.

Antibody Formation↗
PubMed1998

Extracardiac conduit Fontan for children with heterotaxy and functionally single ventricle.

UNLABELLED: Children with functionally single ventricle in the setting of visceral heterotaxy (isomerism) may present a surgical challenge at the time of Fontan completion because of anomalies of systemic and pulmonary venous drainage. We have used an extracardiac conduit in this population to direct inferior caval venous blood to the pulmonary arteries. Over the past five years, nine children with heterotaxy and a functionally single ventricle underwent correction by placement of an extracardiac synthetic (Gore-Tex) conduit. All patients had previously undergone a bidirectional Glenn procedure. Age and weight at the time of insertion of the extracardiac conduit were 26 +/- 15 months, and 11 +/- 2 kilograms, respectively. RESULTS: Of the nine children, six had an uneventful recovery. One developed elevated venous pressures and required a 'fenestration procedure'. Two patients developed pleural effusions. Median length of stay in hospital was 10 days. All children are alive and well, with follow-up of 19 +/- 16 months. There have been no thromboembolic complications. CONCLUSIONS: The extracardiac conduit has worked well in our experience for the completion of the Fontan circulation in children with functionally single ventricle in the setting of visceral heterotaxy.

Abnormalities, Multiple↗
PubMed1998

Neurodevelopmental outcomes in children with Fontan repair of functional single ventricle.

OBJECTIVES: The purpose of this study was to assess the neurodevelopmental status of children after Fontan repair of functional single ventricle and to examine the relationship between cognitive function and selected patient characteristics. STUDY DESIGN: Neurodevelopmental tests including the Stanford-Binet Intelligence (IQ) scale and the Developmental Test of Visual Motor Integration (VMI) were administered to 32 children (26 months to 16 years of age) with complex single ventricle. The mean and distribution of IQ and VMI scores were compared with population norms. The relationship between test scores and patient characteristics was examined utilizing analysis of variance and correlational methods. RESULTS: The majority of children had intellectual function within the normal range (mean, 97.5 +/- 12.1). Below average VMI scores were found in 21.4% of children. There were no significant correlations between intellectual function or visual motor integration ability and preoperative oxygen saturation or age at Fontan. Children who had deep hypothermic circulatory arrest during a prior Norwood procedure tended to have a lower IQ score. CONCLUSIONS: Intellectual development in children with Fontan repair of complex heart defects is essentially within the normal range. Visual motor integration deficits may be more prevalent in these children. In our population, the duration and degree of preoperative hypoxemia had no apparent effect on cognitive function.

Adolescent↗
PubMed1998

Changing practice patterns for children with heart disease: a clinical pathway approach.

BACKGROUND: Pediatric cardiac care is costly and requires extensive resources. We studied the effect of clinical pathways on practice patterns and patient care outcomes in infants and children hospitalized for cardiac surgery. METHODS: In consecutive patients admitted for selected cardiac surgical procedures before (n = 69) and after (n = 173) implementation of clinical pathways, outcomes including hospital length of stay, days in the ICU, time to extubation, ordering of blood studies, costs, and readmissions were compared. Data were analyzed for each of five cardiac surgical procedures: repair of an atrial septal defect, repair of a ventricular septal defect, division of a patent ductus arteriosus, repair of tetralogy of Fallot, and neonatal arterial switch operation to correct transposition of the great arteries. RESULTS: A significant reduction in length of hospital stay, including days in the ICU (decreased 1 to 2 days per admission), was achieved after the clinical pathway was implemented. Reductions in average duration of mechanical ventilation ranged from 28% for repair of a ventricular septal defect to 63% for repair of tetralogy of Fallot. The number of blood studies ordered decreased 20% to 30%. A significant reduction in hospital costs for each procedure, ranging from 16% to 29%, was also achieved with no adverse effects on patients' outcomes. CONCLUSIONS: Use of clinical pathways with children hospitalized for cardiac surgery can shorten length of stay in the hospital, reduce use of resources, and improve cost-effectiveness with beneficial outcomes for patients.

Cardiac Surgical Procedures↗
PubMed1997

Mid- to long-term results of the two-stage approach for type B interrupted aortic arch and ventricular septal defect.

BACKGROUND: Type B interrupted aortic arch with ventricular septal defect is a complex congenital heart defect that may have associated left ventricular outflow tract obstruction. Surgical management has evolved from a two-stage approach to the currently favored single-stage approach. The following data summarize our experience with the two-stage approach over a 15-year period. METHODS: Between 1980 and 1995, 27 consecutive patients with type B interrupted aortic arch and ventricular septal defect underwent surgical management using the two-stage approach. There were 15 girls and 12 boys; 21 patients had the DiGeorge syndrome. RESULTS: Stage I was performed at a median age of 4 days. Twenty-six (96%) of 27 patients survived first-stage palliation. One patient survived stage I palliation but died before undergoing stage II. Twenty-five patients underwent second-stage repair at a median age of 6 weeks (range, 1 to 46 weeks). There were 2 early deaths and 1 late death. Actuarial analysis demonstrates 1- and 5-year survival rates of 85% and 81%, respectively. Twenty-two survivors have been followed up for an average of 8 +/- 2 years. Freedom from reoperation for arch graft enlargement has been 86% at 3 years and 55% at 5 years. Freedom from reoperation for left ventricular outflow tract obstruction has been 82% at both 3 and 5 years. CONCLUSIONS: The two-stage approach can achieve good mid- to long-term palliation of patients with type B interrupted aortic arch and ventricular septal defect. These results should provide a reference from which to gauge the long-term success of the single-stage approach.

Aorta, Thoracic↗
PubMed1996

Aortopulmonary collateral vessels and prolonged pleural effusions after modified Fontan procedures.

Pleural effusions after the modified Fontan procedure are unpredictable, increase morbidity, and prolong hospital stay. To assess the relation between preoperative characteristics and postoperative pleural drainage, we performed a retrospective study of 71 patients who underwent Fontan procedures. Analyses revealed no significant relation between duration of effusion and age at Fontan, preoperative oxygen saturation, pulmonary artery pressure, ventricular end-diastolic pressure, type of Fontan, or prior cavopulmonary anastomosis. Patients with significant aortopulmonary collateral vessels evidenced by angiographic opacification of the pulmonary arteries or veins had more prolonged pleural drainage. The duration of the pleural drainage was significantly less in patients who had aortopulmonary collateral occlusion.

Adolescent↗
PubMed1996

Tetralogy of Fallot repair results in activation of the renin-angiotensin-aldosterone system.

Fluid retention is a common problem following transannular patch repair of tetralogy of Fallot. The present study was undertaken to evaluate whether humoral substances may contribute to this process. Patients undergoing tetralogy of Fallot repair using a transannular patch technique were compared to patients undergoing simple ventricular septal defect repair. Hormone levels were determined by radioimmunoassay. Fluid retention was defined as pleural effusions persisting beyond 5 days. The data demonstrate that patients undergoing tetralogy of Fallot repair had elevated levels of anti-diuretic hormone, renin, angiotensin II, and aldosterone as compared to a group with ventricular septal defect. The elevation in hormone levels in the tetralogy of Fallot group was principally accounted for by those who developed effusions postoperatively. These results suggest that activation of the renin angiotensin-aldosterone system may be one of the contributing factors to fluid retention following tetralogy of Fallot repair.

Aldosterone↗
PubMed1995

Bidirectional Glenn. Is accessory pulmonary blood flow good or bad?

BACKGROUND: The bidirectional Glenn (BDG) is frequently used in the staged surgical management of single ventricle patients. Controversy exists whether accessory pulmonary blood flow (APBF) sources should be left at the time of the BDG to augment systemic saturation or should be eliminated to reduce volume load of the ventricle. The present study was a retrospective review to assess the influence of APBF on outcome after the BDG. METHODS AND RESULTS: Ninety-two patients have undergone BDG at our institute during the interval from 1986 through 1994. At the time of BDG, 40 patients had either a systemic-to-pulmonary artery shunt or patent right ventricular outflow tract as an additional source of pulmonary blood flow. Fifty-two patients had elimination of APBF. There were three operative deaths (two with and one without APBF) and four procedures (two in each group) that failed and required subsequent revision. Thus, there were 85 patients who underwent successful operation. Effusions (defined as chest tube drainage exceeding 7 days' duration) occurred in 8 of 85 patients; this complication was seen in 7 of 36 patients (19%) with APBF and 1 of 49 patients (2%) without APBF (P < .05). There were 11 deaths, including 6 patients (17%) with APBF, 2 patients (4%) without APBF, and 3 of the patients (75%) who had a failed BDG. CONCLUSIONS: The data suggest that morbidity and mortality are lower in patients in whom APBF is eliminated at the time of the BDG.

Adolescent↗
PubMed1995

Factors influencing perioperative morbidity during palliation of the univentricular heart.

BACKGROUND: The modified Fontan procedure has become the treatment of choice for patients born with a univentricular heart. Although the operative mortality has steadily decreased in recent years, the hospital stay is still prolonged in many patients due to fluid retention and pleural effusions. METHODS: We retrospectively analyzed subsets of patients undergoing the bidirectional cavopulmonary shunt (BDCPS) and modified Fontan procedure in an attempt to define factors influencing operative mortality and morbidity. RESULTS: Multivariate analysis of 64 patients undergoing BDCPS revealed that age 6 months or less, concomitant operation, mean pulmonary pressure of 15 mm Hg or less, and mean pulmonary artery ratio of 1.8:1 or less were not statistically significant indicators of risk. Abnormal pulmonary artery architecture was a significant predictor of early and late death (p < or = 0.01). Retrospective analysis of 71 patients undergoing the modified Fontan procedure revealed no significant relationship between duration of pleural effusions and age at operation, preoperative oxygen saturation, pulmonary artery pressure, ventricular end-diastolic pressure, or prior BDCPS: Patients with important aortopulmonary collateral vessels defined by angiography had prolonged pleural drainage. Selective use of the total extracardiac conduit and the fenestrated Fontan resulted in low overall mortality with no statistical differences between subsets of patients undergoing different modifications of the Fontan procedure. CONCLUSIONS: These data indicate that the operative risk for BDCPS or modified Fontan procedure is quite low if a procedure appropriate for the patient is selected. Abnormal pulmonary artery architecture is an important risk factor for death after the BDCPS: Aortopulmonary collateral vessels are associated with fluid retention and pleural effusions after a modified Fontan procedure. Important aortopulmonary collateral vessels should be occluded before or during the modified Fontan procedure.

Adolescent↗
PubMed1995

Renin, angiotensin II, and the development of effusions following bidirectional Glenn and Fontan procedures.

Pleural effusions are a troublesome complication following bidirectional Glenn and Fontan procedures. It was our hypothesis that effusions may be related to alterations in hormones that regulate fluid homeostasis. We made serial determinations (by radioimmunoassay) of antidiuretic hormone, cortisol, aldosterone, angiotensin II, and renin in patients undergoing bidirectional Glenn (n = 16) and Fontan procedures (n = 24). There were six patients who developed effusions following surgery. These patients had a different endocrinological pattern characterized by persistent elevation in renin (28 +/- 9 vs 9 +/- 5 ng/mL per hour, p < 0.01) and angiotensin II (110 +/- 33 vs 33 +/- 14 ng/L, p < 0.01) on the fifth postoperative day as compared to patients who did not develop effusions. These data demonstrate that patients who develop effusions following bidirectional Glenn and Fontan procedures have activation of their renin-angiotensin system.

Adolescent↗
PubMed1994

Comparison of the hormonal response after bidirectional Glenn and Fontan procedures.

Fluid retention is a frequent complication after the bidirectional Glenn and Fontan procedures. It was our hypothesis that this fluid retention may have a hormonal basis. To test this hypothesis, we made serial determinations of antidiuretic hormone, cortisol, aldosterone, angiotensin, and renin before and after operation in patients undergoing a bidirectional Glenn (n = 15) or Fontan (n = 18) procedure. Patients undergoing a bidirectional Glenn procedure had elevations in antidiuretic hormone, cortisol, and aldosterone immediately after operation. However, none of the hormonal elevations persisted by the fifth postoperative day. In contrast, patients undergoing a Fontan procedure had elevations in antidiuretic hormone, cortisol, aldosterone, renin, and angiotensin II in the immediate postoperative period. Five days postoperatively, the renin and angiotensin II levels remained elevated compared with the preoperative values. The data demonstrate that patients undergoing a bidirectional Glenn procedure and those undergoing a Fontan procedure have different patterns of hormonal response. These results suggest that hormonal factors may contribute to fluid retention after these operations.

Aldosterone↗
PubMed1994

Suppression of the pituitary thyroid axis after cardiopulmonary bypass in the neonate.

Thyroid hormone has numerous effects on cardiovascular function in the adult. The present study was undertaken to evaluate the effects of cardiopulmonary bypass and deep hypothermia on thyroid function in the neonate. Ten newborns were studied preoperatively and postoperatively. The total and free triiodothyronine, total and free thyroxine, thyroid-stimulating hormone, and thyroglobulin levels were measured by immunoassays. The data demonstrated a transient rise in the free thyroxine level associated with and followed by significant reductions in the free and total triiodothyronine, total thyroxine, thyroid-stimulating hormone, and thyroglobulin levels in the early postoperative period. By the fifth postoperative day, the free and total triiodothyronine and total thyroxine levels were returning toward the preoperative levels under the influence of an elevated thyroid-stimulating hormone level. These results suggest that the combination of cardiopulmonary bypass and deep hypothermia can result in a transient suppression of the pituitary-thyroid axis in the neonate.

Cardiopulmonary Bypass↗