Lee N. Benson

University Health Network, Toronto, Ontario, Canada

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Publications (410)2002.72 Total impact

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    Full-text · Dataset · Jan 2016
  • Eric Horlick · Lee Benson

    No preview · Article · Dec 2015 · Circulation Cardiovascular Interventions
  • W. Wilson · A. Shah · L. Benson · M. Osten · E. Horlick

    No preview · Article · Dec 2015 · Heart, Lung and Circulation
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    ABSTRACT: Background: Endovascular stenting has emerged as a treatment option for children with coarctation of the aortic (CoA), but the impact on left ventricular (LV) function has been poorly documented. The aim of this study was to characterize the LV myocardial and hemodynamic response to exercise in young patients who underwent endovascular stenting for CoA during childhood using semisupine bicycle exercise stress echocardiography. Methods: This was a single-center prospective cross-sectional study including 30 patients with CoA and 30 age- and gender-matched control subjects who underwent semisupine bicycle exercise stress echocardiography. Color Doppler tissue imaging peak systolic (s') and early diastolic (e') velocities in the LV lateral wall and basal septum, LV myocardial acceleration during isovolumic acceleration were measured at rest and with incremental heart rate (HR). The relationship with increasing HR was evaluated for each parameter by plotting the values at each stage of exercise versus HR. Results: At rest, HR was similar between the two groups. LV ejection fraction and fractional shortening were within the normal range in the CoA group. LV lateral wall and basal septal s' and e' velocities did not differ between the two groups, but isovolumic acceleration values were significantly lower in the CoA group. At peak exercise, HR was similar between the groups, but all Doppler tissue imaging parameters were lower in patients than in control subjects. When assessing the increase of each parameter versus HR, the increase in slope was significantly lower in patients than in control subjects for LV lateral wall Doppler tissue imaging s' and e' velocities, and septal e' velocity, but not for septal s'. The relationship of isovolumic acceleration with HR was significantly reduced in the CoA group. Conclusion: The results of this study demonstrate reduced systolic and diastolic myocardial reserve in patients with CoA compared with control subjects. An abnormal myocardial contractile response to exercise was also found, as shown by an abnormal LV force-frequency relationship in patients with stented CoA. The prognostic clinical implications require further study.
    Full-text · Article · Dec 2015 · Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography
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    ABSTRACT: This study sought to review the outcomes for the Sapien and Sapien XT valves (Edwards Lifesciences, Irvine, California) for percutaneous pulmonary valve implantation (PPVI).
    No preview · Article · Dec 2015
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    Full-text · Article · Nov 2015 · JACC Cardiovascular Interventions
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    ABSTRACT: Objectives: To investigate the effects of local infiltration of 0.25% bupivacaine on post-operative pain and analgesic use in children undergoing cardiac catheterization procedures. Background: In pediatric catheterization procedures performed under general anesthesia, a local anesthetic is often used prior to femoral sheath removal. There are no published reports of the impact of local anesthetic infiltration on pain after pediatric procedures, and mixed reports on its effectiveness in adults. Methods: A randomized controlled trial was undertaken of 140 children, aged 7-18 years undergoing cardiac catheterization under general anesthesia via the femoral vein or artery. Participants received a subcutaneous infiltration of 0.25% bupivacaine at the access site prior to sheath removal, or usual care without bupivacaine. Outcomes included patient reported pain scores and analgesic use up to 6 hr after the procedure. Results: Pain scores were similar between groups through the 6-hr post-procedure period. The proportion of children reporting a maximal pain score of ≤2/10 was higher in the bupivacaine group (64% vs. 44%, P=0.03). A significantly higher proportion of children in the control group required IV morphine (18.8% vs. 4.5%, P=0.02). Conclusions: Morphine use can be reduced with the use of 0.25% bupivacaine given prior to femoral sheath removal and should be considered for post-procedural pain control for pediatric patients undergoing cardiac catheterization. This study is the first to contribute evidence to the effectiveness of 0.25% bupivacaine after pediatric cardiac catheterization.
    No preview · Article · Nov 2015 · Catheterization and Cardiovascular Interventions
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    ABSTRACT: Background: -As US healthcare increasingly focuses upon outcomes as a means for quantifying quality, there is a growing demand for risk models that can account for the variability of patients treated at different hospitals so that equitable comparisons between institutions can be made. We sought to apply aspects of prior risk-standardization methodology in order to begin development of a risk-standardization tool for the NCDR® IMPACT(TM) (Improving Pediatric and Adult Congenital Treatment) Registry. Methods and results: -Using IMPACT, all patients undergoing diagnostic or interventional cardiac catheterization between January 2011 and March 2013 were identified. Multivariable hierarchical logistic regression was used to identify patient and procedural characteristics predictive of experiencing a major adverse event following cardiac catheterization. A total of 19,608 cardiac catheterizations were performed between January 2011 and March 2013. Amongst all cases, a major adverse event occurred in 378 (1.9%) of all cases. After multivariable adjustment, eight variables were identified as critical for risk-standardization: patient age, renal insufficiency, single-ventricle physiology, procedure-type risk group, low systemic saturation, low mixed venous saturation, elevated systemic ventricular end diastolic pressure, and elevated main pulmonary artery pressures. The model had good discrimination (C-statistic of 0.70), confirmed by bootstrap validation (validation C-statistic of 0.69). Conclusions: -Using prior risk-standardization efforts as a foundation, we developed and internally validated a model to predict the occurrence of a major adverse event following cardiac catheterization for congenital heart disease. Future efforts should be directed towards further refinement of the model variables within this large, multicenter dataset.
    No preview · Article · Oct 2015 · Circulation
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    ABSTRACT: Objectives: The objective of this study was to report procedural characteristics and adverse events on the data collected in the IMproving Paediatric and Adult Congenital Treatment registry. Background: The IMproving Paediatric and Adult Congenital Treatment- registry is a catheterisation registry focussed on paediatric and adult patients with congenital heart disease who are undergoing diagnostic catheterisations and catheter-based interventions. This study reports procedural characteristics and adverse events of patients who have undergone selected catheterisation procedures from January, 2011 to June, 2013. Methods: Demographic, clinical, procedural, and institutional data elements were collected at participating centres and entered via either a web-based platform or software provided by the American College of Cardiology-certified vendors, and were collected in a secure, centralised database. For the purpose of this study, procedures that were not classified as one of the 'core' IMproving Paediatric and Adult Congenital Treatment procedures originally chosen for additional data collection were identified and selected for further data analysis. Results: During the time frame of data collection, a total of 8021 cases were classified as other procedures and/or multiple procedures. The most commonly performed case types - isolated or in combination with other procedures - were right ventricular biopsy in 3433 (42.8%), conduit/MPA interventions in 979 (12.3%), and systemic pulmonary artery collateral occlusion in 601 (7.5%). For the whole cohort, adverse events of any severity occurred in 957 (12.0%) cases, whereas major adverse events occurred in 113 (1.4%) cases; six patients (0.1%) died in the catheterisation laboratory. Conclusions: The IMproving Paediatric and Adult Congenital Treatment registry has provided important data on the frequency and spectrum of cardiac catheterisation procedures performed in the present era. For many procedures, more data and work are needed to identify more subtle differences between case categories, especially as it relates to the incidence of major adverse events, and to further develop a risk-adjustment methodology to allow equitable comparisons among institutions.
    No preview · Article · Oct 2015 · Cardiology in the Young
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    Full-text · Article · Oct 2015 · Progress in Pediatric Cardiology
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    ABSTRACT: While well characterized in adult patients, the pattern of hypertrophy and the extent of myocardial scarring in hypertrophic cardiomyopathy (HCM) are insufficiently known. The aim of this study was to assess the hypertrophy patterns and the prevalence and clinical significance of scars in the hearts of young patients with HCM. A retrospective analysis of the imaging findings of 38 children (aged 12.83 ± 2 years, 30 males) with HCM who underwent cardiac magnetic resonance imaging (CMR) was performed. In addition to left ventricular mass and volumes, the examinations were assessed for the pattern of hypertrophy and presence of late gadolinium enhancement (LGE). A myocardial signal intensity ≥6 standard deviations above the mean of normal myocardium defined positive LGE. Left ventricular mass index averaged 110 ± 34 g/m(2) . Nineteen children (50%) had diffuse septal, 13 (34%) diffuse concentric and 6 (16%) isolated basal hypertrophy. Seven children (18%) had LGE. Patients with LGE had a greater left ventricular mass index than those without (136 ± 34 g/m(2) vs. 104 ± 31 g/m(2) , P = .025). The only two patients who presented with an episode of aborted sudden cardiac death had LGE (P = .03). The most common hypertrophy pattern in children with HCM was diffuse septal hypertrophy. The incidence of LGE observed is lower than that reported in adults. The presence of LGE appears to confer a risk for adverse events. © 2015 Wiley Periodicals, Inc.
    No preview · Article · Jul 2015 · Congenital Heart Disease
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    ABSTRACT: Objectives To assess the effectiveness of radiation-reduction measures implemented during pediatric catheterization, and provide data on the radiation doses for common interventional and diagnostic procedures, indexed to body weight.Background Ionizing radiation exposure must be minimized to “as low as reasonably achievable,” by instituting radiation-limiting techniques and knowledge of expected radiation exposure.Methods Radiation-reduction measures included pulsed-fluoroscopy at 7.5 pulses/second (0.032–0.045 µGy/pulse), an air-gap magnification technique for children <20 kg, operator awareness, and additional exposure reduction techniques through projection optimization. Radiation doses for procedures performed between 2007 through 2014 were retrospectively reviewed, including dose area product (DAP) and DAP/kg of body weight for 25 procedural types. Median doses were compared with those previously published from other large centers and multi-institutional databases and assessed for changes over time.ResultsReviewed were 5,196 cases, which included 2,819 interventional, 710 endomyocardial biopsies and 1,667 diagnostic studies, documenting a significant difference in exposure between various procedures and body weights. The absolute exposure was significantly greater in larger children (e.g., for ductal closure median DAP/kg: 17 µGy*m2/kg 10–20 kg children vs. 37 µGy*m2/kg for those >30 kg, P < 0.001). Dose exposure using radiation-reduction techniques were the lowest reported in the literature for all procedure types compared (e.g. median DAP for pulmonary valvuloplasty 163 µGy*m2vs. 405 to 1,230 µGy*m2 reported by 3 large centers). Reduction of fluoroscopy acquisition to 7.5 pulses/second nearly halved radiation exposure (P < 0.001).Conclusions Implementing a radiation dose reduction and awareness program can lead to documented reduction in exposure, across a variety of procedures performed by multiple operators. © 2015 Wiley Periodicals, Inc.
    No preview · Article · May 2015 · Catheterization and Cardiovascular Interventions
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    ABSTRACT: Sirolimus-eluting stents may have clinical advantages over bare-metal stents in the extremely proliferative environment of the neonatal arterial duct. However, sirolimus has immunosuppressive actions and little is known regarding sirolimus pharmacokinetics in the newborn. This is a retrospective review of sirolimus pharmacokinetics in neonates who underwent sirolimus-eluting stent implantation in the arterial duct for pulmonary blood flow augmentation. Pharmacokinetic parameters were obtained by noncompartmental analysis and by a Bayesian one-compartment nonlinear mixed model. Nine neonates received a single sirolimus-eluting stent with a total sirolimus dose of 245 μg (n=1), 194 μg (n=5), or 143 μg (n=3). Peak sirolimus concentrations were 13.6±4.5 μg/L (24.8 μg/L highest) and clearance was 0.042±0.03 L/hour (noncompartmental analysis) and 0.051 L/hour (95% credible intervals 0.037-0.069, nonlinear mixed model). Sirolimus remained >5 μg/L, the trough level used in oral immunosuppressive therapy, for (95% credible interval) 15.9 (11.4, 22.8), 12.9 (7.6, 19.0), and 8.4 (2.3, 14.5) days for the 245, 194, and 143 μg sirolimus dose stents, respectively. Estimates of the duration of systemic immunosuppression are provided for combinations of 2 stents. In neonates after sirolimus-eluting stent implantation, peak sirolimus levels were 20× higher and clearance 30× lower than previously reported in older children and adults. Sirolimus levels were within the immunosuppressive range for a prolonged period, but with no observable clinically significant adverse outcomes. © 2015 American Heart Association, Inc.
    No preview · Article · May 2015 · Circulation Cardiovascular Interventions
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    ABSTRACT: The aim of the study was to examine the role of three-dimensional rotational angiography (3DRA) in assessing vascular and airway narrowing in children with a bidirectional cavopulmonary anastomosis (BCPA). The course of children with single ventricle physiology is often complicated by left pulmonary artery (LPA) and/or bronchial stenosis and may be related to aortic compression. 3DRA may be useful in evaluating this complex anatomy and possible mechanisms for the observed obstruction. Clinical data and imaging (2D angiography and 3DRA) of children with a BCPA were reviewed retrospectively. Measurements were taken at similar locations along the pulmonary arteries in both modalities and in the airways on 3DRA. Twenty-five children with a previous BCPA were assessed at mean age of 3.1 ± 2.0 years and weight of 13.6 ± 3.6 kg. Excellent correlation was found between 3DRA and 2D angiographic LPA measurements (r = 0.89, p < 0.0001). Twelve children had qualitative LPA stenosis on 3DRA, with a stenotic dimension of 6.6 ± 2.2 mm on 2D angiography and 6.8 ± 1.9 mm on 3DRA (r = 0.94, p < 0.0001). Ten cases with LPA stenosis also had bronchial stenosis (83 %). Qualitative airway assessment correlated with quantitative bronchial dimensions from 3DRA-derived tomographic images: Bronchial stenosis measured 4.4 ± 1.6 versus 5.9 ± 1.1 mm in those with a normal appearing bronchus (p = 0.009). Hybrid patients (initial palliation with bilateral pulmonary artery banding and arterial ductal stenting, n = 5) and all patients with a Damus-Kaye-Stansel (DKS) anastomosis (n = 9) were more likely to have LPA and left bronchial stenosis (OR 7.7, p = 0.04). 3DRA is a useful and accurate tool in assessment of LPA and airway narrowing after BCPA. Hybrid and DKS patients are more prone to LPA and bronchial stenosis, and 3DRA can provide insight into the mechanism.
    No preview · Article · Mar 2015 · Pediatric Cardiology
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    ABSTRACT: To report procedural characteristics and adverse events on data collected in the registry. The IMPACT - IMproving Paediatric and Adult Congenital Treatment - Registry is a catheterisation registry of paediatric and adult patients with CHD undergoing diagnostic and interventional cardiac catheterisation. We are reporting the procedural characteristics and adverse events of patients undergoing diagnostic and interventional catheterisation procedures from January, 2011 to March, 2013. Demographic, clinical, procedural, and institutional data elements were collected at the participating centres and entered via either a web-based platform or software provided by American College of Cardiology-certified vendors, and were collected in a secure, centralised database. Centre participation was voluntary. During the time frame of data collection, 19,797 procedures were entered into the IMPACT Registry. Procedures were classified as diagnostic only (35.4%); one of six specific interventions (23.8%); other or multiple interventions (40.7%); and were further broken down into four age groups. Anaesthesia was used in 84.1% of diagnostic procedures and 87.8% of interventional ones. Adverse events occurred in 10.0% of diagnostic and 11.1% of interventional procedures. The IMPACT Registry is gathering data to set national benchmarks for diagnostic and certain specific interventional procedures. We are seeing little differences in procedural characteristics or adverse events in diagnostic procedures compared with interventional procedures overall, but there is significant variation in adverse events amongst age categories. Risk stratification and patient acuity scores will be required for further analysis of these differences.
    No preview · Article · Feb 2015 · Cardiology in the Young
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    ABSTRACT: Objectives This study was designed to compare outcomes of the most common pediatric cardiac interventions from the time of implementation with the current era.Background Since the introduction of semilunar valve balloon dilation and device closure of the arterial duct and septal defects, development of interventional techniques and devices has been rapid. However, few studies have compared outcomes between those initial interventions and those in the current era.Methods Five validated common catheter-based therapies were chosen for analysis, including atrial and duct device closure, balloon dilation of the aortic and pulmonary valves, and native coarctation of the aorta. A retrospective review of the first and most recent 10 consecutive patients in each group was performed.ResultsThere was a high mortality (30%) among neonates who underwent aortic valve (AV) dilation in the early era, but no mortality noted in other groups. In the early era, transcatheter atrial defect closure and AV dilations were associated with a low success rate (60% for both lesions) and a high complication rate (40% for atrial septal defect, 30% for AV dilations). Among the last 10 children, the atrial defect occlusion was successful in 100% without complications and AV dilations where successful in all children with a 30% complication rate (one major, two minor).ConclusionsA learning curve with device development plays a significant role in the evolution of transcatheter techniques. These data provide baseline estimates of success and may be used as a template in the future when new techniques are adapted into practice.
    No preview · Article · Feb 2015 · Congenital Heart Disease
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    ABSTRACT: Percutaneous pulmonary valve implantation (PPVI) is a safe, less invasive alternative to surgical valve replacement for the congenital heart disease patient with right ventricular (RV) outflow tract dysfunction. The aim of this study was to determine whether reverse RV remodeling after PPVI was persistent in the longer term and whether timing of PPVI influenced outcomes. Consecutive patients from the pediatric and adult congenital heart disease programs were enrolled. Cardiac MRI, echocardiography, metabolic exercise testing, chest radiography, and hemodynamics before intervention were compared with repeated follow-up measurements to assess changes over time. Fifty-one patients (including 23 patients <16 years old) were followed for a mean 4.5±1.9 (0.9-6.9) years after implantation, 59% of patients having available comparative cardiac MRI data. Freedom from any reintervention was 87% and 68% at 3 and 5 years, and freedom from surgery was 90% at 5 years. For every decade younger at implantation, there was an increase of 3.9%±1.0% in cardiac MRI left ventricular ejection fraction (P<0.001) and 2.4±0.9 mL/kg/min in maxVO2 (P=0.005) and a decrease of 0.7±0.2 cm in RV end-diastolic dimension (P<0.001) after intervention. Younger patients displayed an additional decline in the RV/left ventricular end-diastolic volume ratio (P=0.05) and trended toward improved RV ejection fraction in late follow-up (50%±7% versus 41%±12%, P=0.07). This is the largest series to show that PPVI at a younger age yields incremental improvements in RV size and maximum oxygen consumption. Early valve implantation is associated with better RV function and should be considered in management planning for this population. © 2015 American Heart Association, Inc.
    Full-text · Article · Feb 2015 · Circulation Cardiovascular Interventions
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    ABSTRACT: The purpose of this study was to evaluate the presence of diffuse myocardial fibrosis in children and adolescents with hypertrophic cardiomyopathy (HCM) and to assess associations with echocardiographic and clinical parameters of disease. While a common end point in adults with HCM, it is unclear whether diffuse myocardial fibrosis occurs early in the disease. Cardiac magnetic resonance (CMR) estimation of myocardial post-contrast longitudinal relaxation time (T1) is an increasingly used method to estimate diffuse fibrosis. T1 measurements were taken using standard multi-breath-hold spoiled gradient echo phase-sensitive inversion-recovery CMR before and 15 min after the injection of gadolinium. The tissue-blood partition coefficient was calculated as a function of the ratio of T1 change of myocardium compared with blood. An echocardiogram and blood brain natriuretic peptide (BNP) levels were obtained on the day of the CMR. Twelve controls (mean age 12.8 years; 7 male) and 28 patients with HCM (mean age 12.8 years; 21 male) participated. The partition coefficient for both septal (0.27 ± 0.17 vs. 0.13 ± 0.09; p = 0.03) and lateral walls (0.22 ± 0.09 vs. 0.07 ± 0.10; p 100 pg/ml) had raised lateral wall coefficients (0.27 ± 0.07 vs. 0.20 ± 0.07; p = 0.03), as did those with traditional risk factors for sudden death (0.27 ± 0.06 vs. 0.18 ± 0.08; p = 0.007). Diffuse fibrosis, measured by the partition coefficient technique, is demonstrable in children and adolescents with HCM. Markers of fibrosis show an association with symptoms and raised serum BNP. Further study of the prognostic implication of this technique in young patients with HCM is warranted.
    No preview · Article · Jan 2015 · Pediatric Cardiology
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    ABSTRACT: Valve pathology is a significant component of pediatric cardiovascular disease. Outside the pediatric age group, patients are selecting bioprosthetic valve replacements to avoid the obligate anticoagulation associated with mechanical valves either because of the inability to take anticoagulation, pregnancy considerations, or preference. Bioprosthetic valves, however, inevitably degenerate. The standard treatment is a repeat operation that entails additional risk. Transcatheter valve therapy has rapidly emerged as an appealing alternative. In this manuscript, we discuss the progress in transcatheter valve-in-valve (VinV) procedures. This is essential knowledge for the practicing pediatric cardiologist as it may promote the application of bioprosthetic valves as a treatment option and management strategy.
    No preview · Article · Jan 2015 · Progress in Pediatric Cardiology
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    Lee N. Benson · Juan Pablo Sandoval Jones

    Full-text · Chapter · Jan 2015

Publication Stats

11k Citations
2,002.72 Total Impact Points


  • 2015
    • University Health Network
      • Department of Cardiology
      Toronto, Ontario, Canada
  • 1987-2015
    • UHN: Toronto General Hospital
      Toronto, Ontario, Canada
  • 1985-2015
    • University of Toronto
      • • Division of Paediatric Medicine
      • • Labatt Family Heart Centre
      • • Department of Paediatrics
      • • Division of Cardiology
      • • Hospital for Sick Children
      • • Faculty of Medicine
      Toronto, Ontario, Canada
  • 1980-2015
    • SickKids
      • • Division of Cardiology
      • • Division of Clinical Pharmacology and Toxicology
      • • Department of Diagnostic Imaging
      • • Division of Cardiovascular Surgery
      Toronto, Ontario, Canada
  • 1995
    • Toronto Western Hospital
      Toronto, Ontario, Canada
  • 1986
    • Children's Hospital Los Angeles
      Los Ángeles, California, United States