Lee N Benson

University of Toronto, Toronto, Ontario, Canada

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Publications (308)1579.82 Total impact

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    Progress in Pediatric Cardiology 10/2015; DOI:10.1016/j.ppedcard.2015.10.016
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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.
    Congenital Heart Disease 07/2015; DOI:10.1111/chd.12286 · 1.08 Impact Factor
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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.
    Catheterization and Cardiovascular Interventions 05/2015; DOI:10.1002/ccd.26024 · 2.11 Impact Factor
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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.
    Pediatric Cardiology 03/2015; 36(5). DOI:10.1007/s00246-015-1130-8 · 1.31 Impact Factor
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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.
    Congenital Heart Disease 02/2015; 10(4). DOI:10.1111/chd.12247 · 1.08 Impact Factor
  • W. Wilson · A. Shah · L. Benson · M. Osten · E. Horlick ·

    Heart, Lung and Circulation 01/2015; 24:S432-S433. DOI:10.1016/j.hlc.2015.06.744 · 1.44 Impact Factor
  • W. Wilson · E. Horlick · L. Benson ·
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    ABSTRACT: We describe a case of a Scimitar syndrome “variant” where dual drainage existed from the right upper and middle pulmonary veins to the inferior vena cava and left atrium. Device closure of the anomalous vein at the level of the connection to the IVC was successful in achieving diversion of pulmonary venous flow to the left atrium. Vigilance during work-up of anomalous pulmonary venous drainage (whether isolated or associated with other cardiac defects that may be amenable to device closure) is important to define the presence of dual connections to the left atrium, in which case a less-invasive transcatheter approach may be feasible. © 2014 Wiley Periodicals, Inc.
    Catheterization and Cardiovascular Interventions 11/2014; 85(7). DOI:10.1002/ccd.25734 · 2.11 Impact Factor
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    Andrea W Wan · Kyong-Jin Lee · Lee N Benson ·
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    ABSTRACT: Covered stents have been used for the treatment of aortic coarctation to protect the arterial wall during dilation. Early results have shown them to be safe and effective. We report 2 cases of infolding of the proximal edge of a covered aortic coarctation stent. Management required implantation of a second stent. Poor stent apposition to the vessel wall and or recoil may allow conditions for these events to occur. © 2013 Wiley Periodicals, Inc.
    Catheterization and Cardiovascular Interventions 01/2014; 83(1). DOI:10.1002/ccd.24998 · 2.11 Impact Factor
  • L Grosse-Wortmann · J Windram · D Andreea · S Yoo · L Mertens · D Wong · L Benson ·

    The Canadian journal of cardiology 10/2013; 29(10):S97. DOI:10.1016/j.cjca.2013.07.118 · 3.71 Impact Factor
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    ABSTRACT: All 3 palliation strategies, Norwood, Sano, and Hybrid, currently used for hypoplastic left heart syndrome pose a risk of myocardial injury at different times and through different mechanisms. We sought to compare these strategies to understand longitudinal differences in interstage ventricular dysfunction and their subsequent impact on transplant-free survival and atrioventricular valve regurgitation (AVVR) as well as the relationship between adverse events and ventricular function. Serial echocardiographic reports and clinical data were reviewed for 138 children with hypoplastic left heart syndrome who underwent stage I surgical palliation (Sano: 11; Norwood: 73; Hybrid: 54) between 2004 and 2011. Stage II palliation was achieved in 92 (67%) patients (Sano: 7; Norwood: 51; Hybrid: 34). Interstage transplant-free survival, ventricular dysfunction, and AVVR were equivalent among palliation strategies. Patients with preserved ventricular function had a higher rate of transplant-free survival and freedom from AVVR, regardless of palliation strategy. Patients who had cardiac arrest, cardiopulmonary resuscitation, or extracorporeal membrane oxygenation (adverse events) experienced more transient and persistent ventricular dysfunction compared to those without adverse events. Surgical palliation strategies were not identified as risk factors for ventricular dysfunction or AVVR. Surgical palliation strategy does not affect mortality, interstage ventricular function, or interstage AVVR in children with hypoplastic left heart syndrome. Therefore, the different timing and mechanisms of myocardial injury among palliation strategies do not affect outcomes. Ventricular dysfunction adversely affects transplant-free survival and atrioventricular valve function. Adverse events are associated with the development of ventricular dysfunction. To improve outcomes, interstage treatment should focus on the preservation of ventricular function.
    Circulation 09/2013; 128(26 Suppl 1):S205-12. DOI:10.1161/CIRCULATIONAHA.112.000380 · 14.43 Impact Factor
  • Harsimran S Singh · Eric Horlick · Mark Osten · Lee N Benson ·
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    ABSTRACT: Interventional cardiac catheterization has become an integral component of the management of adults with congenital heart disease. The origins of this approach come from the paediatric interventional experience, although techniques and indications for interventional cardiac catheterization in adults are now being developed for use in the burgeoning field of adult congenital heart disease. Progress in the application and acceptance of interventional cardiac catheterization in this setting has been swift, and the pace is quickening. This Review provides a broad overview of some of the most common procedures used in the treatment of adults with congenital heart lesions, with an emphasis on new tools that have revolutionized the field. Specifically, we discuss interventions that can be broadly classified into the following groups: techniques for closing shunt lesions, valvular interventions, methods for achieving patency of vascular obstructions, and selected additional interventions applicable to some complex lesions. We emphasize the need for a thorough understanding of the anatomy of the lesion, its natural or unnatural history, and indications for intervention before the procedure takes place. Such procedures must be performed in centres where the operators are knowledgeable of the lesions being addressed, with full surgical, anaesthetic, nursing and imaging support.
    Nature Reviews Cardiology 08/2013; 10(11). DOI:10.1038/nrcardio.2013.127 · 9.18 Impact Factor
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    ABSTRACT: We sought to assess the efficacy, safety and clinical outcomes of the Advanta V12™ covered stent in management of coarctation of the aorta (CoA). Stent functionality was assessed by review of angiographic imaging, clinical data at admission, discharge and at the last clinic visit, stent configuration on chest roentgenogram, radiation exposure, and complications. Between October 2009 and February 2012, 17 patients underwent stent implantation. There were 9-12, 2-14, and 6-16 mm diameter stents deployed. Balloon angioplasty after implantation was required in 2 patients. Mean percent recoil in the middle of the stent for the 12, 14, and 16 mm implants was 14%, 24%, and 24%, respectively. There was improvement in CoA diameter from 6.6 ± 3.2 to 11.5 ± 1.7 mm (P < 0.0001) and a reduction in the peak pressure gradient from 23.1 ± 10.1 to 0.8 ± 3.3 mmHg (P < 0.0001). No patient had a symptomatic complication. Left arm cuff blood pressure fell 24 hours after implantation and left arm to leg blood pressure gradient fell to <20 mmHg in all (P < 0.0001). Follow-up was a median 242 days and at the last clinic visit there were no statistically different findings from discharge. Five children (33%) required antihypertensive medications but 3 were off medication at latest follow-up. Three patients (18%) required reintervention. The implantation of the Advanta™ V12 stent for the treatment of CoA is safe and effective in the early term. However, further study is required to determine longer-term stent efficacy.
    Journal of Interventional Cardiology 08/2013; 26(4):411-6. DOI:10.1111/joic.12043 · 1.18 Impact Factor
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    ABSTRACT: Background: Transcatheter (percutaneous) pulmonary valve (TPV) replacement has emerged as a viable therapy for right ventricular outflow tract conduit dysfunction. Little is known about the incidence, clinical course, and outcome of infective endocarditis (IE) after TPV implant. We reviewed combined data from 3 ongoing prospective multicenter trials to evaluate the experience with IE among patients undergoing TPV replacement using the Melody valve. Methods and results: Any clinical episode reported by investigators as IE with documented positive blood cultures and fever, regardless of TPV involvement, was considered IE. Cases were classified as TPV-related if there was evidence of vegetations on or new dysfunction of the TPV. The 3 trials included 311 patients followed for 687.1 patient-years (median, 2.5 years). Sixteen patients were diagnosed with IE 50 days to 4.7 years after TPV implant (median, 1.3 years), including 6 who met criteria for TPV-related IE: 3 with vegetations, 2 with TPV dysfunction, and 1 with both. The annualized rate of a first episode of IE was 2.4% per patient-year and of TPV-related IE was 0.88% per patient-year. Freedom from TPV-related IE was 97±1% 4 years after implant. All patients were treated with intravenous antibiotics, 4 had the valve explanted, and 2 received a second TPV. There was 1 sepsis-related death, 1 patient died of sudden hemoptysis, and 2 patients developed recurrent IE. Conclusions: Bacterial endocarditis has occurred in all 3 prospective multicenter studies of the Melody valve in North America and Europe. Most cases did not involve the TPV and responded to antibiotics. More data are necessary to understand risk factors in this population.
    Circulation Cardiovascular Interventions 06/2013; 6(3). DOI:10.1161/CIRCINTERVENTIONS.112.000087 · 6.22 Impact Factor
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    ABSTRACT: Background: Ductal stenting plays a central role in hybrid palliation (with bilateral pulmonary artery [PA] banding) for hypoplastic left heart syndrome (HLHS). The "natural" history of ductal stent is relatively unknown. Methods: We retrospectively reviewed 37 neonates with HLHS or its variants who underwent hybrid palliation between January 2004 and March 2010. Results: Forty-nine ductal stents were deployed in 37 neonates. A single stent was implanted in 26, 2 in 10, and 3 in 1 neonate at the index procedure. There were 5 neonates (13.5%) who required reintervention on the stent with an additional implant; 4 stents were placed proximally (PA-end) and 1 on the aorta side. No infant required reintervention on the stent if the implant covered from the PA junction to beyond the aortic isthmus. There were 2 infants (5.4%) who developed retrograde arch obstruction. Of the cohort, 9 died before stage II, 1 had a bidirectional cavopulmonary shunt after conversion to a Norwood circulation, and 27 underwent comprehensive stage II. In 24 infants who did not require an additional stent, duct velocity increased during follow-up (p < 0.001). Stent position was altered distally in relation to the anterior border of the trachea with child growth. Conclusions: The stent should cover the full length of the duct from the PA junction to beyond the arch isthmus to reduce reintervention rates. Such stents tend to have progressive stenosis and move distally with child growth. However, lower body blood flow appears well maintained until the time of a comprehensive stage II repair.
    The Annals of thoracic surgery 03/2013; 95(5). DOI:10.1016/j.athoracsur.2013.02.002 · 3.85 Impact Factor
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    ABSTRACT: We describe 3 distinct ACHD lesions amenable to percutaneous repair: (1) venous baffle obstruction in transposition of the great arteries, (2) coronary artery fistulas, and (3) ruptured sinus of Valsalva aneurysms. For each entity, we chronicle the typical clinical scenario and indications for intervention to supplement the technical approach and potential pitfalls with treatment.
    01/2013; 2(1):153–172. DOI:10.1016/j.iccl.2012.09.010
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    ABSTRACT: Objective: Retrograde aortic arch malperfusion after ductal stenting can be life-threatening after univentricular hybrid palliation. Arch perfusion can be maintained with a main pulmonary artery to innominate artery shunt placed during the stage I procedure: a "reverse Blalock-Taussig shunt." Methods: A retrospective review of 37 infants who underwent hybrid palliation from January 2004 to March 2010 was performed. The infants were divided into 2 groups, those with (group I, n = 16) and those without (group II, n = 21) a reverse Blalock-Taussig shunt. Results: At the initial palliation, no differences were found in the demographics, systolic or diastolic pressures, or ventricular or atrioventricular valve function between the 2 groups. Group I had more infants with aortic atresia (P < .01) and smaller ascending aortas (P < .01). Before stage II, the retrograde aortic Doppler flow velocity increased in group I (P < .01) and was unchanged in group II. The reintervention rates before stage II were similar between the 2 groups. Before stage II, the ventricular end-diastolic pressure, left and right pulmonary artery pressures and diameters, and mixed venous and arterial saturations were similar between the 2 groups. The complication rates between the 2 groups were not significantly different, although a nonsignificant trend toward more neurologic complications was noted in group I. The Kaplan-Meier survival estimate at 1 year was similar between the 2 groups (63% for group I vs 71% for group II). Conclusions: The presence of a reverse Blalock-Taussig shunt was not associated with more adverse events than those without. Gradual retrograde arch obstruction occurs commonly in palliated infants with aortic atresia. A reverse Blalock-Taussig shunt might play an important role to address the potential of retrograde obstruction, augmenting arch blood flow.
    The Journal of thoracic and cardiovascular surgery 12/2012; 146(2). DOI:10.1016/j.jtcvs.2012.11.029 · 4.17 Impact Factor
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    ABSTRACT: Hybrid and Norwood strategies differ substantially in terms of stage II palliative procedures. We sought to compare these strategies with an emphasis on survival and reintervention after stage II and subsequent Fontan completion. Of 110 neonates with functionally single-ventricle physiology who underwent stage I palliation between 2004 and 2010, 75 (69%) infants (Norwood, n=43; hybrid, n=32) who subsequently underwent stage II palliation were studied. Survival and reintervention rates after stage II palliation, anatomic and physiologic variables at pre-Fontan assessment, and Fontan outcomes were compared between the groups. Predictors for reintervention were analyzed. Freedom from death/transplant after stage II palliation was equivalent between the groups (Norwood, 80.4% versus hybrid, 85.6% at 3 years, P=0.66). Hybrid patients had a higher pulmonary artery (PA) reintervention rate (P=0.003) and lower Nakata index at pre-Fontan evaluation (P=0.015). Aortic arch and atrioventricular valve reinterventions were not different between the groups. Ventricular end-diastolic pressure, mean PA pressure, and ventricular function were equivalent at pre-Fontan assessment. There were no deaths after Fontan completion in either group (Norwood, n=25, hybrid, n=14). Survival after stage II palliation and subsequent Fontan completion is equivalent between the groups. The hybrid group had a higher PA reintervention rate and smaller PA size. Both strategies achieved adequate physiology for Fontan completion. Evolution of the hybrid strategy requires refinement to provide optimal PA growth.
    Circulation 09/2012; 126(11 Suppl 1):S123-31. DOI:10.1161/CIRCULATIONAHA.111.084616 · 14.43 Impact Factor

  • The Canadian journal of cardiology 09/2012; 28(5):S410-S411. DOI:10.1016/j.cjca.2012.07.727 · 3.71 Impact Factor
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    ABSTRACT: We report 4 cases of left main coronary artery (LMCA) compression after remote repair of conotruncal lesions and their successful surgical management.
    The Annals of thoracic surgery 05/2012; 94(1):283-5. DOI:10.1016/j.athoracsur.2011.12.048 · 3.85 Impact Factor
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    ABSTRACT: Diastolic dysfunction of the right ventricle (RV) is common after repair of tetralogy of Fallot. While restrictive physiology in late diastole has been well known, dysfunction in early diastole has not been described. The present study sought to assess the prevalence and mechanism of early diastolic dysfunction of the RV defined as delayed onset of the tricuspid valve (TV) flow after TOF repair. The study population consisted of 31 children with repaired TOF (mean age ± SD, 12.3 ± 4.1 years) who underwent postoperative cardiovascular magnetic resonance (CMR). The CMR protocol included simultaneous phase-contrast velocity mapping of the atrioventricular valves, which enabled direct comparison of the timing and patterns of tricuspid (TV) and mitral (MV) valve flow. The TV flow was defined to have delayed onset when its onset was > 20 ms later than the onset of the MV flow. The TV and MV flow from 14 normal children was used for comparison. The CMR results were correlated with the findings on echocardiography and electrocardiography. Delayed onset of the TV flow was observed in 16/31 patients and in none of the controls. The mean delay time was 64.81 ± 27.07 ms (8.7 ± 3.2% of R-R interval). The delay time correlated with the differences in duration of the TV and MV flow (55.94 ± 32.88 ms) (r = 0.90, p < 0.001). Delayed onset was associated with prolongation of the RV ejection time in 9 and delayed onset and cessation of the pulmonary arterial flow in 4. Delayed onset was not associated with timing changes in the pulmonary artery in 3. The patients with delayed onset showed reduced RV ejection fraction (p = 0.01). However, the two groups did not show significant differences in TV E/A ratio, ventricular end-diastolic volumes, left ventricular ejection fraction, pulmonary regurgitant fraction, heart rate, PR interval and QRS duration. Early diastolic dysfunction with delayed onset of TV flow is common after TOF repair, and is associated with reduced RV ejection fraction. It is a further manifestation of interventricular dyssynchrony and represent an additional mechanism of ventricular diastolic dysfunction.
    Journal of Cardiovascular Magnetic Resonance 08/2011; 13(1):43. DOI:10.1186/1532-429X-13-43 · 4.56 Impact Factor

Publication Stats

8k Citations
1,579.82 Total Impact Points


  • 1985-2015
    • University of Toronto
      • • Division of Paediatric Medicine
      • • Labatt Family Heart Centre
      • • Division of Cardiology
      • • Department of Paediatrics
      • • Hospital for Sick Children
      • • Department of Medicine
      • • Faculty of Medicine
      Toronto, Ontario, Canada
  • 1980-2015
    • SickKids
      • • Division of Cardiology
      • • Division of Cardiovascular Surgery
      • • Division of Clinical Pharmacology and Toxicology
      • • Department of Paediatrics
      • • Department of Diagnostic Imaging
      Toronto, Ontario, Canada
  • 1987-2008
    • UHN: Toronto General Hospital
      Toronto, Ontario, Canada
  • 1986-1995
    • Toronto Western Hospital
      Toronto, Ontario, Canada
  • 1993
    • Hackensack University Medical Center
      Хакенсак, New Jersey, United States