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Biomedical subjects

Brian W Duncan

Publications and source records attributed to Brian W Duncan.

At least 19 recordsLinked to original sources
PubMed2006

Aortic valve repair for congenital abnormalities of the aortic valve.

BACKGROUND: Due to shortcomings of any valve replacement, repairing and retaining the native valve may be beneficial for congenital aortic valve disease. METHODS: Retrospective review of data and follow-up of aortic valve repair from a single institution. RESULTS: From 1993 to 2001, 56 patients underwent aortic valve repair [median age 13.4 years (range 1 day to 45 years)]. The predominant aortic valve lesion was mixed aortic stenosis/aortic insufficiency 25 (45%), aortic insufficiency 24 (43%) and aortic stenosis 7 (13%). Repair techniques included sub-commissural plication 36 (64%), commissurotomy 24 (43%), cusp plication 15 (27%), pericardial patch cusp extension 8 (14%) and resuspension of commissures 4 (7%). Most patients (88%) required a combination of techniques; 61% required additional procedures. Hospital survival was 55/56 [98%; (95% CI 91-100%)] no patient was discharged on anticoagulation for aortic valve pathology. Fifty-three patients [95%; (95% CI 85-98%)] remain alive after a median follow-up of 37 months; four survivors required aortic valve replacement and two required repeat aortic valve repair [84%; (95% CI 72-91%) reintervention-free survival]. CONCLUSIONS: (1) In this study, aortic valve repair for congenital abnormalities avoided reoperation in the majority of patients, avoided anticoagulation and retained growth potential of the valve. (2) Repeat aortic valve repair or replacement was used to treat subsequent valve deterioration.

Adolescent↗
PubMed2006

Outcomes of children bridged to heart transplantation with ventricular assist devices: a multi-institutional study.

BACKGROUND: Current ventricular assist devices (VADs) in the United States are designed primarily for adult use. Data on VADs as a bridge to transplantation in children are limited. METHODS AND RESULTS: A multi-institutional, prospectively maintained database of outcomes in children after listing for heart transplantation (n=2375) was used to analyze outcomes of VAD patients (n=99, 4%) listed between January 1993 and December 2003. Median age at VAD implantation was 13.3 years (range, 2 days to 17.9 years); diagnoses were cardiomyopathy (78%) and congenital heart disease (22%). Mean duration of support was 57 days (range, 1 to 465 days). Seventy-three percent were supported with a long-term device, with 39% requiring biventricular support. Seventy-seven patients (77%) survived to transplantation, 5 patients were successfully weaned from support and recovered, and 17 patients (17%) died on support. In the recent era (2000 to 2003), successful bridge to transplantation with VAD was achieved in 86% of patients. Peak hazard for death while waiting was the first 2 weeks after VAD placement. Risk factors for death while awaiting a transplant included earlier era of implantation (P=0.05), female gender (P=0.02), and congenital disease diagnosis (P=0.05). There was no difference in 5-year survival after transplantation for patients on VAD at time of transplantation as compared with those not requiring VAD. CONCLUSIONS: VAD support in children successfully bridged 77% of patients to transplantation, with posttransplantation outcomes comparable to those not requiring VAD. These encouraging results emphasize the need to further understand patient selection and to delineate the impact of VAD technology for children.

Adolescent↗
PubMed2006

The National Heart, Lung, and Blood Institute Pediatric Circulatory Support Program.

Options for the circulatory support of pediatric patients under the age of 5 years are currently limited to short-term extracorporeal devices, the use of which is often complicated by infection, bleeding, and thromboembolism. Recognizing this void, the National Heart, Lung, and Blood Institute solicited proposals for the development of novel circulatory support systems for infants and children from 2 to 25 kg with congenital or acquired cardiovascular disease. Five contracts were awarded to develop a family of devices that includes (1) an implantable mixed-flow ventricular assist device designed specifically for patients up to 2 years of age, (2) another mixed-flow ventricular assist device that can be implanted intravascularly or extravascularly depending on patient size, (3) compact integrated pediatric cardiopulmonary assist systems, (4) apically implanted axial-flow ventricular assist devices, and (5) pulsatile-flow ventricular assist devices. The common objective for these devices is to reliably provide circulatory support for infants and children while minimizing risks related to infection, bleeding, and thromboembolism. The devices are expected to be ready for clinical studies at the conclusion of the awards in 2009.

Child, Preschool↗
PubMed2006

Quantitative analysis of procalcitonin after pediatric cardiothoracic surgery.

Procalcitonin appears to be an early and sensitive marker of bacterial infection in a variety of clinical settings. The use of levels of procalcitonin to predict infection in children undergoing cardiac surgery, however, may be complicated by the systemic inflammatory response that normally accompanies cardiopulmonary bypass. The aim of our study was to estimate peri-operative concentrations of procalcitonin in non-infected children undergoing cardiac surgery. Samples of serum for assay of procalcitonin were obtained in 53 patients at baseline, 24, 48, and 72 hours following cardiac surgery. Concentrations were assessed using an immunoluminetric technique. Median concentrations were lowest at baseline at less than 0.5 nanograms per millilitre, increased at 24 hours to 1.8 nanograms per millilitre, maximized at 48 hours at 2.1 nanograms per millilitre, and decreased at 72 hours to 1.3 nanograms per millilitre, but did not return to baseline levels. Ratios of concentrations between 24, 48 and 72 hours after surgery as compared to baseline were 6.15, with 95 percent confidence intervals between 4.60 and 8.23, 6.49, with 95 percent confidence intervals from 4.55 to 9.27, and 4.26, with 95 percent confidence intervals between 2.78 and 6.51, respectively, with a p value less than 0.001. In 8 patients, who had no evidence of infection, concentrations during the period from 24 to 72 hours were well above the median for the group. We conclude that concentrations of procalcitonin in the serum increase significantly in children following cardiac surgery, with a peak at 48 hours, and do not return to baseline within 72 hours of surgery. A proportion of patients, in the absence of infection, had exaggerated elevations post-operatively.

Adolescent↗
PubMed2006

Mechanical cardiac support in the young. Short-term support: ECMO.

Although based on technology developed several decades ago, extracorporeal membrane oxygenation (ECMO) retains great clinical relevance in the management of advanced pediatric cardiorespiratory disease. Largely because of its widespread use in pediatric patients with respiratory failure, familiarity with this technology has established ECMO as the most commonly used form of mechanical circulatory support in children. Clinical applications and technical aspects of ECMO support continue to evolve, ensuring the ongoing importance of this modality for pediatric circulatory support.

Age Factors↗
PubMed2005

Long-term outcome of surgically treated patients with corrected transposition of the great arteries.

OBJECTIVES: The purpose of the study was to examine long-term outcome after traditional surgical treatment of corrected transposition of the great arteries to provide a basis for comparison with new procedures, such as the double-switch or Senning-Rastelli procedures. METHODS: Patient- and procedure-related variables in 123 patients with corrected transposition and 2 functional ventricles operated on between 1963 and 1996 were analyzed. Patients with intracardiac procedures underwent either a traditional 2-ventricle repair or a Fontan procedure. RESULTS: The 1-, 5-, 10-, and 15-year survivals after the operation were 84%, 75%, 68%, and 61%, respectively. Patients requiring tricuspid valve replacement (27 patients) at any time during follow-up had a significantly worse outcome ( P < .001; hazard ratio, 4.4), whereas the best outcome was seen in patients undergoing the Fontan procedure (17 patients, 0 deaths). Right ventricular end-diastolic pressure of greater than 17 mm Hg before the operation ( P < .0001), complete heart block after the operation ( P = .001), subvalvular pulmonary stenosis ( P = .013), Ebstein malformation of the tricuspid valve ( P = .025), and preoperative systemic (right) ventricular dysfunction ( P = .041) were identified as risk factors for death at any time by means of univariate analysis. Ebstein malformation of the tricuspid valve ( P = .036; hazard ratio, 1.5) was identified as a risk factor for death by multivariate analysis. CONCLUSIONS: The long-term outcome of patients with corrected transposition after a classic surgical approach is unsatisfactory. The poorest outcome was seen in patients who required tricuspid valve replacement either at their initial operation or later during follow-up. Alternative surgical approaches, such as the double-switch, Senning-Rastelli, or Fontan procedures, are likely to have better long-term results, especially in the highest risk groups.

Analysis of Variance↗
PubMed2005

Management of the failing systemic right ventricle.

Conditions in which the right ventricle serves as the systemic pumping chamber are frequently complicated by the development of right ventricular failure and tricuspid valve regurgitation. The right ventricle is the systemic ventricle in conditions of ventriculoarterial discordance with atrioventricular concordance (transposition of the great arteries) or with atrioventricular discordance (congenitally corrected transposition of the great arteries). Concerns regarding actual or potential systemic right ventricular failure in these cases may lead to surgical evaluation and treatment designed to reestablish the left ventricle as the systemic pump. In cases where the left ventricle has prolonged exposure to low pressures in the pulmonary circulation, the left ventricle must be "retrained" to assume a systemic pressure load. Anatomic repair, with or without a preparatory period of left ventricular retraining, is a consideration for three clinically relevant scenarios: (1) patients with transposition of the great arteries after an atrial level switch (Senning or Mustard procedure), (2) patients with congenitally corrected transposition who are unoperated or who have undergone physiologic ("classic") repair, and (3) unoperated patients with transposition who present after the neonatal period.

Cardiac Surgical Procedures↗
PubMed2005

The PediPump: a new ventricular assist device for children.

Options for mechanical circulatory support for the treatment of end-stage heart failure in children are limited. Ventricular assist devices (VADs), which have revolutionized cardiac care in adults, remain largely unavailable for pediatric applications. The PediPump is a new rotary dynamic VAD designed to provide support for the entire range of patient sizes encountered in pediatrics. Despite being much smaller than currently available VADs, which makes it suitable for even newborn circulatory support, the PediPump demonstrates excellent hemodynamic performance.

Child↗
PubMed2004

Selective timing for the arterial switch operation.

BACKGROUND: To determine outcomes for the arterial switch operation individualized according to the underlying anatomy and clinical status. METHODS: A retrospective review of a consecutive series of infants less than 90 days of age who underwent the arterial switch operation at a single institution. RESULTS: From July 1993-April 2001, 117 infants underwent an arterial switch operation before 90 days of age. Seventy-five patients (64%) had transposition of the great arteries with intact ventricular septum with the aim of operation before 14 days of age; however, 8 of these patients had delayed presentation (range 15-46 days). Thirty-five patients (30%) had transposition with a ventricular septal defect (30 patients) or double outlet right ventricle (5 patients) and normal arch anatomy and were repaired within the first 90 days of life depending on the severity of heart failure at a median of 12 days of age (range 3-83 days). Seven patients (6%) had associated aortic coarctation (5 patients) or interrupted aortic arch (2 patients). One patient died during hospitalization (0.85% hospital mortality) and one patient died from noncardiac causes during a median follow-up of 35 months (1.7% total mortality). Four patients required intervention during follow-up (3.4%) for new aortic coarctation (2 patients), supravalvar pulmonic stenosis (1 patient), or right hemi-diaphragm paralysis (1 patient). CONCLUSIONS: Individualized timing for the arterial switch operation within the first ninety days of life produces excellent survival rates for all types of transposition physiology with the expectation of a satisfactory course during follow-up.

Coronary Vessel Anomalies↗
PubMed2004

Apical right ventriculotomy for closure of apical ventricular septal defects.

BACKGROUND: Apical ventricular septal defects (VSDs) are difficult to visualize through a transatrial approach, while the use of a left ventriculotomy may result in progressive ventricular dysfunction. Transcatheter closure has not been reliable, especially in small infants. Apical right ventriculotomy provides good exposure, preserves left ventricular function, and allows secure closure of apical VSDs. METHODS: From November 1994 through April 2002, nine children, median age 8 months (range, 74 days to 2.5 years) underwent 10 operations for VSD closure via apical right ventriculotomy (one patient with a residual defect underwent successful VSD closure via a second apical right ventriculotomy). Two patients were status post pulmonary artery banding and two patients had previous unsuccessful attempts at closure via a transatrial approach. RESULTS: There was no hospital mortality; there were 2 late deaths (78% survival; 95% confidence interval [CI], 45% to 94%), 3 months and 4 years postoperatively. Postoperative echocardiography demonstrated no residual VSDs in 3 and insignificant residual VSDs in 4 of the survivors. All survivors currently exhibit normal biventricular function during a median follow-up of 25 months (range, 11 to 104 months). CONCLUSIONS: Apical right ventriculotomy provides excellent exposure allowing safe and effective closure of apical VSDs. The observed late morbidity and mortality reflects the complexity that often exists in these cases due to additional irreparable lesions.

Cardiopulmonary Bypass↗
PubMed2003

Anatomic correction for corrected transposition after pulmonary unifocalization.

A Senning plus Rastelli operation was performed in a patient who had a rare combination of congenitally corrected transposition of the great arteries (S,L,L) with dextrocardia, major aortopulmonary collaterals, and diminutive central pulmonary arteries with arborization defects. The patient required four preparatory operations including bilateral unifocalizations of the aortopulmonary artery collaterals. Pulmonary artery to systemic pressure ratio after the double switch operation was 0.6. The patient demonstrates good biventricular function on echocardiogram at 3 months after the operation.

Aorta, Thoracic↗
PubMed2003

Pulmonary arteriovenous malformations after cavopulmonary anastomosis.

Pulmonary arteriovenous malformations (PAVMs) are a cause of progressive cyanosis after cavopulmonary anastomosis in children with single ventricle physiology who are on the pathway leading to a Fontan procedure. Investigations into possible mechanisms for the etiology of PAVMs are ongoing and suggest that the liver might play a key regulatory role in the development of these lesions.

Animals↗
PubMed2003

Comparison of autograft and allograft aortic valve replacement in children.

OBJECTIVE: This study was undertaken to compare the clinical and hemodynamic results following aortic valve replacement with a pulmonary valve autograft (Ross procedure) or an allograft valve in children. METHODS: The records of 107 pediatric aortic valve replacements from 1994 through 2001 were reviewed, including 78 autografts and 25 allografts. Four mechanical aortic valve replacements performed during this period were excluded from analysis. RESULTS: There were 3 perioperative deaths and 1 late death. Reoperations were required in 5 autograft recipients (with autograft preservation in 4) and in 3 allograft recipients (all requiring valve re-replacement). Seven-year survival (96% in both groups) and reoperation-free survival (88% in the autograft group; 73% in the allograft group, P =.5) were not significantly different. Serial echocardiographic studies showed that in the autograft group, left ventricular outflow tract maximal velocity (2.0-1.8 m/s, P =.02) and left ventricular thickness (10.1-8.4 mm, P <.0001) fell significantly. In the allograft group, maximal velocity (2.3-3.0 m/s, P =.03) increased significantly and left ventricular thickness (9.5-9.0 mm, P =.2) showed minimal change. Analysis according to preoperative physiology (aortic stenosis versus insufficiency), congenital cardiac anatomy, number or type of previous operations, age of patient, and use of balloon valvotomy did not predict outcomes. CONCLUSIONS: Aortic valve replacement with either the autograft or allograft provides excellent clinical results in children during an intermediate duration of observation. The Ross procedure achieves a superior hemodynamic result, which may be clinically important with longer follow-up.

Adolescent↗