Clinical Focus

  • Pediatrics
  • Pediatric Cardiology
  • Cardiac Catheterization
  • Echocardiography

Professional Education

  • Board Certification: Royal College of Physicians and Surgeons of Canada, Pediatrics (1994)
  • Fellowship: Hospital for Sick Children Pediatric Cardiology (1998) Canada
  • Board Certification: Royal College of Physicians and Surgeons of Canada, Pediatric Cardiology (1997)
  • Fellowship: Hospital for Sick Children Pediatric Cardiology (1997) Canada
  • Residency: Hospital For Sick Children (1994) Canada
  • Internship: University of Toronto (1990) Canada
  • Medical Education: University of Toronto MD Program (1989) Canada

All Publications

  • The COAST Is Not Clear: Late Aneurysms and Fractures. Circulation. Cardiovascular interventions Adamson, G. T., Lee, K. J. 2021: CIRCINTERVENTIONS121010886
  • Balloon Angioplasty for Native Aortic Coarctation in 3- to 12-Month-Old Infants. Circulation. Cardiovascular interventions Sandoval, J. P., Kang, S. L., Lee, K. J., Benson, L., Asoh, K., Chaturvedi, R. R. 2020; 13 (11): e008938


    Balloon angioplasty for native coarctation of the aorta (CoA) is successful in children and adults but in neonates results in frequent restenosis. The efficacy of balloon angioplasty for native CoA during infancy beyond the neonatal period was examined in infants aged 3 to 12 months of age.A retrospective review of 68 infants who underwent balloon angioplasty for native CoA. 95% CI are in parentheses.Procedural age was (mean±SD) 6±3.4 months and weight was 7±1.8 kg. Balloon angioplasty produced a large decrease in both the noninvasive arm-to-leg blood pressure gradient (41.2±18.7 to 5.6±9.6 mm Hg) and the invasive peak systolic pressure gradient (34±12 to 11±9 mm Hg). Balloon angioplasty increased the CoA diameter from 2.7±1 mm to 4.6±1.2 mm. One patient was lost to follow-up. A catheter reintervention was required in 11.8% and surgery in 10.3%. The hazard of reintervention was highest early. Median freedom from reintervention was 89% (95% CI, 80%-96%) at 1 year, 83% (95% CI, 73%-92%) at 5 years, and 81% (95% CI, 69%-90%) at 10 years. Femoral artery thrombosis was documented in 6 (9%) infants without any long-term consequence. One patient developed a small aortic aneurysm late and has not required treatment. A robust estimate of the frequency of aortic aneurysms remains to be determined as the majority of subjects have not had cross-sectional imaging.Balloon angioplasty of native CoA is effective and safe in infants aged 3 to 12 months with outcomes comparable to those in older children and adults. Catheter reinterventions can avoid the need for surgery in most patients.

    View details for DOI 10.1161/CIRCINTERVENTIONS.120.008938

    View details for PubMedID 33167702

  • Using the arterial cannula for cardiac catheterization in neonates and small infants supported by extracorporeal membrane oxygenation. The Journal of thoracic and cardiovascular surgery Kang, S. L., Lee, K. J., Stanisic, A., Chaturvedi, R. R. 2019

    View details for DOI 10.1016/j.jtcvs.2019.03.119

    View details for PubMedID 31126658

  • Automated 3-Dimensional Single-Beat Real-Time Volume Colour Flow Doppler Echocardiography in Children: A Validation Study of Right and Left Heart Flows. The Canadian journal of cardiology Kato, A., Sandoval, J. P., Mroczek, D., Chaturvedi, R., Houle, H., Georgescu, B., Yoo, S. J., Benson, L. N., Lee, K. J. 2018; 34 (6): 726-735


    Novel quantification of stroke volume according to mitral inflow and aortic outflow using automated real-time 3-dimensional volume colour flow Doppler echocardiography (3D-RT-VCFDE) is more accurate than 2-dimensional echocardiography and has excellent correlation with cardiac magnetic resonance imaging-based flows in adults. This technology is applied for the first time to the right heart and in children.3D-RT-VCFDE was performed in 61 image sets of flow through the aortic (AV), mitral (MV), pulmonary (PV), and tricuspid (TV) valves of 34 children. These were compared with stroke volumes of the right (RV) and left (LV) ventricles and ratio of pulmonary to systemic blood flow determined using the Fick method in 31 children with atrial shunts.The mean age was 8.0 ± 3.3 years, and the mean weight was 27.8 ± 10.0 kg. The mean temporal resolution for flow analyses was ≥ 22 volumes per second. In conditions with no shunt, the correlations were: AV with MV flows (r = 0.98), PV with TV flows (r = 0.96), RV stroke volume with PV flow (r = 0.95), and with TV flow (r = 0.93), LV stroke volume with AV flow (r = 0.87), and with MV flow (r = 0.89). Fick ratio of pulmonary to systemic blood flow correlations were: PV/AV ratio (r = 0.84), TV/MV ratio (r = 0.87), and RV/LV ratio (r = 0.70).Stroke volume determined using automated 3D-RT-VCFDE is feasible in children and in the right side of the heart. This technique potentially provides a noninvasive alternative to historically invasively acquired hemodynamic data and to cardiac magnetic resonance imaging.

    View details for DOI 10.1016/j.cjca.2018.03.001

    View details for PubMedID 29801738

  • Right Ventricular Outflow Tract Stenting in Tetralogy of Fallot Infants With Risk Factors for Early Primary Repair. Circulation. Cardiovascular interventions Sandoval, J. P., Chaturvedi, R. R., Benson, L., Morgan, G., Van Arsdell, G., Honjo, O., Caldarone, C., Lee, K. J. 2016; 9 (12)


    Tetralogy of Fallot with cyanosis requiring surgical repair in early infancy reflects poor anatomy and is associated with more clinical instability and longer hospitalization than those who can be electively repaired later. We bridged symptomatic infants with risk factors for early primary repair by right ventricular outflow tract stenting (stent).Four groups of tetralogy of Fallot with confluent central pulmonary arteries were studied: stent group (n=42), primary repair (aged <3 months) with pulmonary stenosis (early-PS group; n=44), primary repair (aged <3 months) with pulmonary atresia (early-PA group; n=49), and primary repair between 3 and 11 months of age (surg>3mo group; n=45). Stent patients had the smallest pulmonary arteries with a median (95% credible intervals) Nakata index (mm2/m2) of 79 (66-85) compared with the early-PA 139 (129-154), early-PS 136 (121-153), and surg>3mo 167 (153-200) groups. Only stent infants required unifocalization of aortopulmonary collaterals (17%). Stent and early-PA infants had younger age and lower weight than early-PS infants. Stent infants had the most multiple comorbidities. Stenting allowed deferral of complete surgical repair to an age (6 months), weight (6.3 [5.8-7.0] kg), and Nakata index (147 [132-165]) similar to the low-risk surg>3mo group. The 3 early treatment groups had similar intensive care unit/hospital stays and high reintervention rates in the first 12 months after repair, compared with the surg>3mo group.Right ventricular outflow tract stenting of symptomatic tetralogy of Fallot with poor anatomy (small pulmonary arteries) and adverse factors (multiple comorbidities, low weight) relieves cyanosis and defers surgical repair. This allowed pulmonary arterial and somatic growth with clinical results comparable to early surgical repair in more favorable patients.

    View details for DOI 10.1161/CIRCINTERVENTIONS.116.003979

    View details for PubMedID 27965298

  • Pulmonary artery stenosis in hybrid single-ventricle palliation: High incidence of left pulmonary artery intervention. The Journal of thoracic and cardiovascular surgery Rahkonen, O., Chaturvedi, R. R., Benson, L., Honjo, O., Caldarone, C. A., Lee, K. J. 2015; 149 (4): 1102-10.e2


    Pulmonary artery growth is an important determinant of outcome in single-ventricle strategies. Higher rates of pulmonary artery intervention have been reported with hybrid-based palliation when compared with Norwood palliation.We performed a retrospective review of pulmonary artery growth and clinical outcomes in patients undergoing hybrid-based single-ventricle palliation.The stage I hybrid procedure was performed in 72 patients between 2004 and 2012, of whom 54 were on a Fontan palliative pathway. Thirty-four infants completed stage II, and 20 infants underwent the Fontan operation. The mean diameters of the right pulmonary artery (5.6 ± 1.9 mm) and left pulmonary artery (5.6 ± 2.1 mm) were similar before stage II. After stage II, the right and left pulmonary artery diameters were 8.5 ± 2.1 mm and 5.8 ± 1.3 mm, respectively (P < .001), and after the Fontan operation, these were 8.8 ± 2.0 mm and 6.4 ± 1.1 mm, respectively (P = .002). The mean right pulmonary artery z score was normal throughout, but the left pulmonary artery did not maintain a normal size. The cumulative pulmonary artery intervention rate was 50% at any time after stage II. Fifteen interventions (88%) were performed after stage II (35% during the same hospitalization, 71% <60 days). The most intervened site was the midsection of the left pulmonary artery (41%). Initial pulmonary artery intervention was balloon dilation in 59% of patients and stent implantation in 41% of patients. Half of patients with initial balloon dilation required reintervention.There is significant risk of left pulmonary artery compromise after the second stage of hybrid palliation associated with a high intervention rate.

    View details for DOI 10.1016/j.jtcvs.2014.11.080

    View details for PubMedID 25595374

  • Percutaneous pulmonary valve implantation: 5 years of follow-up: does age influence outcomes? Circulation. Cardiovascular interventions Borik, S., Crean, A., Horlick, E., Osten, M., Lee, K. J., Chaturvedi, R., Friedberg, M. K., McCrindle, B. W., Manlhiot, C., Benson, L. 2015; 8 (2): e001745


    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.

    View details for DOI 10.1161/CIRCINTERVENTIONS.114.001745

    View details for PubMedID 25652317

  • Pharmacokinetics of sirolimus-eluting stents implanted in the neonatal arterial duct. Circulation. Cardiovascular interventions Lee, K. J., Seto, W., Benson, L., Chaturvedi, R. R. 2015; 8 (5)


    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.

    View details for DOI 10.1161/CIRCINTERVENTIONS.114.002233

    View details for PubMedID 25940522

  • Impact of pre-stage II hemodynamics and pulmonary artery anatomy on 12-month outcomes in the Pediatric Heart Network Single Ventricle Reconstruction trial. The Journal of thoracic and cardiovascular surgery Aiyagari, R., Rhodes, J. F., Shrader, P., Radtke, W. A., Bandisode, V. M., Bergersen, L., Gillespie, M. J., Gray, R. G., Guey, L. T., Hill, K. D., Hirsch, R., Kim, D. W., Lee, K. J., Pelech, A. N., Ringewald, J., Takao, C., Vincent, J. A., Ohye, R. G. 2014; 148 (4): 1467-74


    To compare the interstage cardiac catheterization hemodynamic and angiographic findings between shunt types for the Pediatric Heart Network Single Ventricle Reconstruction trial. The trial, which randomized subjects to a modified Blalock-Taussig shunt (MBTS) or right ventricle-to-pulmonary artery shunt (RVPAS) for the Norwood procedure, demonstrated the RVPAS was associated with a smaller pulmonary artery diameter but superior 12-month transplant-free survival.We analyzed the pre-stage II catheterization data for the trial subjects. The hemodynamic variables and shunt and pulmonary angiographic data were compared between shunt types; their association with 12-month transplant-free survival was also evaluated.Of 549 randomized subjects, 389 underwent pre-stage II catheterization. A smaller size, lower aortic and superior vena cava saturation, and higher ventricular end-diastolic pressure were associated with worse 12-month transplant-free survival. The MBTS group had a lower coronary perfusion pressure (27 vs 32 mm Hg; P<.001) and greater pulmonary blood flow/systemic blood flow ratio (1.1 vs 1.0, P=.009). A greater pulmonary blood flow/systemic blood flow ratio increased the risk of death or transplantation only in the RVPAS group (P=.01). The MBTS group had fewer shunt (14% vs 28%, P=.004) and severe left pulmonary artery (0.7% vs 9.2%, P=.003) stenoses, larger mid-main branch pulmonary artery diameters, and greater Nakata indexes (164 vs 134, P<.001).Compared with the RVPAS subjects, the MBTS subjects had more hemodynamic abnormalities related to shunt physiology, and the RVPAS subjects had more shunt or pulmonary obstruction of a severe degree and inferior pulmonary artery growth at pre-stage II catheterization. A lower body surface area, greater ventricular end-diastolic pressure, and lower superior vena cava saturation were associated with worse 12-month transplant-free survival.

    View details for DOI 10.1016/j.jtcvs.2013.10.057

    View details for PubMedID 24332668

    View details for PubMedCentralID PMC4053497

  • Intervention for recoarctation in the single ventricle reconstruction trial: incidence, risk, and outcomes. Circulation Hill, K. D., Rhodes, J. F., Aiyagari, R., Baker, G. H., Bergersen, L., Chai, P. J., Fleming, G. A., Fudge, J. C., Gillespie, M. J., Gray, R. G., Hirsch, R., Lee, K. J., Li, J. S., Ohye, R. G., Oster, M. E., Pasquali, S. K., Pelech, A. N., Radtke, W. A., Takao, C. M., Vincent, J. A., Hornik, C. P. 2013; 128 (9): 954-61


    Recoarctation after the Norwood procedure increases risk for mortality. The Single Ventricle Reconstruction (SVR) trial randomized subjects with a single right ventricle undergoing a Norwood procedure to a modified Blalock-Taussig shunt or a right ventricle-pulmonary artery shunt. We sought to determine the incidence of recoarctation, risk factors, and outcomes in the SVR trial.Recoarctation was defined by intervention, either catheter based or surgical. Univariate analysis and multivariable Cox proportional hazard models were performed with adjustment for center. Of the 549 SVR subjects, 97 (18%) underwent 131 interventions (92 balloon aortoplasty, 39 surgical) for recoarctation at a median age of 4.9 months (range, 1.1-10.5 months). Intervention typically occurred at pre-stage II catheterization (n=71, 54%) or at stage II surgery (n=38, 29%). In multivariable analysis, recoarctation was associated with the shunt type in place at the end of the Norwood procedure (hazard ratio, 2.0 for right ventricle-pulmonary artery shunt versus modified Blalock-Taussig shunt; P=0.02), and Norwood discharge peak echo-Doppler arch gradient (hazard ratio, 1.07 per 1 mm Hg; P<0.01). Subjects with recoarctation demonstrated comorbidities at pre-stage II evaluation, including higher pulmonary arterial pressures (15.4±3.0 versus 14.5±3.5 mm Hg; P=0.05), higher pulmonary vascular resistance (2.6±1.6 versus 2.0±1.0 Wood units·m(2); P=0.04), and increased echocardiographic volumes (end-diastolic volume, 126±39 versus 112±33 mL/BSA(1.3), where BSA is body surface area; P=0.02). There was no difference in 12-month postrandomization transplantation-free survival between those with and without recoarctation (P=0.14).Recoarctation is common after Norwood and contributes to pre-stage II comorbidities. Although with intervention there is no associated increase in 1-year transplantation/mortality, further evaluation is warranted to evaluate the effects of associated morbidities.

    View details for DOI 10.1161/CIRCULATIONAHA.112.000488

    View details for PubMedID 23864006

    View details for PubMedCentralID PMC3825266

  • Hybrid versus Norwood strategies for single-ventricle palliation. Circulation Baba, K., Kotani, Y., Chetan, D., Chaturvedi, R. R., Lee, K. J., Benson, L. N., Grosse-Wortmann, L., Van Arsdell, G. S., Caldarone, C. A., Honjo, O. 2012; 126 (11 Suppl 1): S123-31


    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.

    View details for DOI 10.1161/CIRCULATIONAHA.111.084616

    View details for PubMedID 22965972

  • The impact of additional epicardial imaging to transesophageal echocardiography on intraoperative detection of residual lesions in congenital heart surgery. The Journal of thoracic and cardiovascular surgery Dragulescu, A., Golding, F., Van Arsdell, G., Caldarone, C., Mertens, L., Al-Radi, O., Lee, K. J. 2012; 143 (2): 361-7


    Transesophageal echocardiography is the primary intraoperative imaging modality used to evaluate cardiac surgery. Its predecessor, epicardial echocardiography, enables visualization of certain cardiovascular structures that are beyond the visual scope of transesophageal echocardiography. We review the current use of epicardial echocardiography to analyze its contemporary application and benefit.A retrospective review of the intraoperative echocardiograms of 1204 children undergoing bypass cardiovascular surgery between January 2007 and December 2009 was performed. The incidence of epicardial echocardiography use, intraoperative revisions, and early reinterventions were analyzed.Epicardial echocardiography was performed in 7.9% of all intraoperative studies: epicardial echocardiography alone (n = 38) and transesophageal echocardiography + epicardial echocardiography (n = 57). Epicardial echocardiography alone was performed in patients with contraindications for transesophageal echocardiography. In the transesophageal echocardiography + epicardial echocardiography group, indications to obtain additional information by epicardial echocardiography were for the assessment of branch pulmonary arteries (40%), coronary arteries (28%), aortic arch/Blalock-Taussig shunt (14%), Glenn/Fontan circuit (9%), pulmonary veins/baffles (7%), and residual ventricular septal defects (1.7%). The overall intraoperative surgical revision incidence was 10.2%, consisting of 21% of the transesophageal echocardiography + epicardial echocardiography group, 5.3% of the epicardial echocardiography alone group (P = .01), and 9.8% of transesophageal echocardiography alone group (P = .02). Intraoperative revisions indicated after epicardial echocardiography were mostly related to extracardiac structures (77%), whereas they were mostly related to intracardiac structures in the transesophageal echocardiography alone group (80.7%) (P = .0002). Early reintervention was indicated mostly for pulmonary artery and Glenn obstructions, the majority (75%) with previously known stenosis or interventions on the pulmonary arteries.Epicardial echocardiography detects residual intraoperative lesions not visualized by transesophageal echocardiography, most frequently related to pulmonary arteries. Its use, in addition to standard transesophageal echocardiography, may decrease the need for early reintervention.

    View details for DOI 10.1016/j.jtcvs.2011.06.010

    View details for PubMedID 21752399

  • Delayed repair of right atrial isomerism with obstructed total anomalous pulmonary venous drainage by hybrid stent insertion between the left-sided atrium and pulmonary venous confluence. The Journal of thoracic and cardiovascular surgery Chaturvedi, R. R., Van Arsdell, G. S., Jacques, F., Lee, K. J. 2012; 144 (1): 271-3

    View details for DOI 10.1016/j.jtcvs.2011.12.056

    View details for PubMedID 22381351

  • Acute effects of the ACE inhibitor enalaprilat on the pulmonary, cerebral and systemic blood flow and resistance after the bidirectional cavopulmonary connection. Heart (British Cardiac Society) Lee, K. J., Yoo, S. J., Holtby, H., Grant, B., Mroczek, D., Wong, D., Grosse-Wortmann, L., Benson, L. N., Chaturvedi, R. R. 2011; 97 (16): 1343-8


    The bidirectional cavopulmonary connection (BCPC) is used in the staged palliation of univentricular hearts and places the cerebral and pulmonary vascular beds in series. Angiotensin-converting enzyme inhibitors (ACEI) are often used in this complex circulation, but the effects of their vasodilation are unclear.Assessment of the acute response of perfusion pressure, flow and resistance across the systemic, cerebral and pulmonary vascular beds to ACEI in patients with a BCPC.Prospective interventional study.Single tertiary care centre.12 patients with a BCPC (median age 28 months, weight 11.8 kg) undergoing a pre-Fontan catheterisation with MRI measurement of flows.Intravenous enalaprilat 0.005 or 0.01 mg/kg.Enalaprilat increased descending aorta flow (median 21.6%, p=0.0005), decreased total pulmonary vein flow (median 10.6%, p=0.025), and both superior caval vein flow (median 8.6%, p=0.065) and aortopulmonary collateral flow (median 15.5%, p=0.077) tended to decrease. Total cardiac output was unchanged (p=0.57). Systemic vascular resistance (median 41.9%, p=0.0005) and cerebral vascular resistance (median 23.4%, p=0.0005) decreased, but pulmonary vascular resistance (p=0.73) showed little change. There was evidence of autoregulation of cerebral blood flow. The proportion of descending aortic flow to total cardiac output increased (median 27 to 35%, p=0.001). Systemic oxygen saturation decreased from 87% to 83% (p=0.02).Enalaprilat did not increase total cardiac output but redistributed flow to the lower body, with a concomitant decrease in arterial oxygen saturation. It is difficult to increase cardiac output in patients with a BCPC and ACEI should be used with caution in those with borderline aortic saturations.

    View details for DOI 10.1136/hrt.2011.225656

    View details for PubMedID 21646245

  • Percutaneous pulmonary valve implantation within bioprosthetic valves. European heart journal Asoh, K., Walsh, M., Hickey, E., Nagiub, M., Chaturvedi, R., Lee, K. J., Benson, L. N. 2010; 31 (11): 1404-9


    Replacement of bioprosthetic valves in the right ventricular (RV) outflow tract (RVOT) is inevitable due to acquired valvar dysfunction. Percutaneous pulmonary valve implantation (PPVI) may result in acceptable clinical improvement avoiding surgical reintervention. To report outcomes of PPVI in dysfunctional surgically implanted bioprosthetic valves.All children undergoing PPVI into a bioprosthetic pulmonary valve between October 2005 and February 2008 were reviewed. Acute haemodynamic changes were compared and an analysis of variance applied to assess changes in ventricular geometry and pressure over time. Fourteen children (seven males), median weight 57.8 kg and 14.7 years of age were identified, with an echocardiographic RVOT gradient of 59.6 +/- 26.8 mmHg and a pulmonary regurgitation (PR) grade of 3.6 +/- 0.8 (out of 4). Implantation was successful in all. Twenty-four hours after implantation, there was a significant improvement in RV pressure (RVP) (from 82.2 +/- 15.6 to 59.4 +/- 9.9 mmHg, P < 0.001) and degree of PR to 0.6 +/- 0.9 (P < 0.001). Mean hospital stay was 2.0 +/- 0.4 days. Freedom from reintervention was 92 and 89% at 1 and 2 years, respectively. Follow-up echocardiography (mean 12.9 +/- 9.8 months) revealed a further reduction in RVP (P < 0.001) and RVOT gradients (P < 0.001) and an increase in left ventricular end-diastolic volume (P= 0.01) and aortic valve annulus diameters (P < 0.001).Percutaneous pulmonary valve implantation for RVOT dysfunction in a previously implanted prosthetic valve is feasible and safe. Short-term follow-up data are encouraging, yet longer-term information is required to determine if this form of palliation has a significant impact on management strategies.

    View details for DOI 10.1093/eurheartj/ehq056

    View details for PubMedID 20231157

  • Percutaneous pulmonary valve implantation in the young 2-year follow-up. JACC. Cardiovascular interventions Vezmar, M., Chaturvedi, R., Lee, K. J., Almeida, C., Manlhiot, C., McCrindle, B. W., Horlick, E. M., Benson, L. N. 2010; 3 (4): 439-48


    The aim of this study was to investigate physiological and clinical consequences of percutaneous pulmonary valve implantation (PPVI) in patients with chronic right ventricular outflow tract (RVOT) obstruction and volume overload.The PPVI is a nonsurgical technique to address RVOT conduit dysfunction.Twenty-eight adolescents (median age 14.9 years; age range 10.9 to 19 years) underwent PPVI due to RVOT stenosis and/or pulmonary regurgitation (PR). Before and after PPVI echocardiographic and magnetic resonance imaging, cardiopulmonary exercise tests were obtained.The RVOT gradient (p < 0.001) and right ventricular (RV) systolic pressure decreased (p < 0.001), acutely. Magnetic resonance imaging (median 6 months) documented reduction in RV end-diastolic (149 +/- 49 ml/m(2) vs. 114 +/- 35 ml/m(2), p < 0.005) volume, increases in left ventricular (LV) end-diastolic (p < 0.007) volume and cardiac output (RV: p < 0.04 and LV: p < 0.02), and reduced PR fraction (24 +/- 10% to 7 +/- 7%, p < 0.0001). Symptoms, aerobic exercise performance (maximal oxygen consumption: p < 0.0001) and ventilatory response to carbon dioxide production (p < 0.003) improved. After 24 months, echocardiography demonstrated the RV/systemic-pressure ratio, and RVOT peak pressure gradient reductions persisted, and PR was absent in 93% (n = 12 of 13) of the cohort. Freedom from surgery was 91%, 83%, and 83%, and freedom from transcatheter reintervention was 91%, 80%, and 80%, at 12, 24, and 36 months, respectively. There were no acute device-related complications, with stent fractures noted in 10.8%.Percutaneous pulmonary valve implantation is feasible and safe in the young with dysfunctional RVOT conduits. An improvement in symptoms, hemodynamic status, and objective findings of exercise performance occurs. Early follow-up demonstrates persistent improvement in ventricular parameters, PR, and objective exercise capacity.

    View details for DOI 10.1016/j.jcin.2010.02.003

    View details for PubMedID 20398873

  • Rapamycin-eluting stents in the arterial duct: experimental observations in the pig model. Circulation Lee, K. J., Hinek, A., Chaturvedi, R. R., Almeida, C. L., Honjo, O., Koren, G., Benson, L. N. 2009; 119 (15): 2078-85


    Maintaining arterial duct patency by stent implantation may be advantageous in congenital heart disease management algorithms. Rapamycin, an immunosuppressant drug that demonstrates antiproliferative properties and inhibits smooth muscle cell migration, may deter the intimal hyperplasia that occurs during spontaneous closure and after-stent implantation of the arterial duct.Twenty-eight Yorkshire piglets (7 to 11 days old; weight, 2.2 to 4.9 kg) underwent stent implantation of the arterial duct (rapamycin-eluting (n=14) or bare metal (n=14) stents, 3.5-mm diameter) and were euthanized at 2, 4, and 6 weeks. Dissected arterial ducts were analyzed for lumen diameter, smooth muscle cell, and extracellular matrix components. Isolated arterial duct-derived smooth muscle cells were cultured in the presence or absence of rapamycin. Cellular proliferation rates were assessed by Ki-67 detection and [(3)H]-thymidine incorporation. No significant neointimal proliferation was present in either stent type at 2 weeks. At 4 weeks, the median luminal diameters of the bare metal stents were 87% (P=0.009), 54% (P=0.004), and 77% (P=0.004) that of the drug-eluting stents at the middle and aortic and pulmonary artery ends, respectively. At 6 weeks, the median luminal diameters of the bare metal stents were 0% (P=0.18), 5% (P=0.25), and 61% (P=0.13) that of the drug-eluting stents at the same respective levels. Complete histological occlusion was found in at least 1 level of the lumen in 9 pigs: 1 (17%) in the BMS group at 4 weeks, 5 (83%) in the BMS group at 6 weeks, and 3 (50%) in the DES group at 6 weeks. In vitro studies demonstrated 50%-lower proliferation rates in rapamycin-treated cultures of duct-derived smooth muscle cell cultures (P<0.001).Rapamycin has antiproliferative actions on the arterial duct. Drug-eluting stents may be a more efficient tool than current palliative options for maintaining patency in critically duct-dependent states, but there may be a finite time-related benefit.

    View details for DOI 10.1161/CIRCULATIONAHA.107.737734

    View details for PubMedID 19349326

  • Stenting of the right ventricular outflow tract in the symptomatic infant with tetralogy of Fallot. Heart (British Cardiac Society) Dohlen, G., Chaturvedi, R. R., Benson, L. N., Ozawa, A., Van Arsdell, G. S., Fruitman, D. S., Lee, K. J. 2009; 95 (2): 142-7


    Repair of neonatal tetralogy of Fallot (TOF) has low mortality. Debate continues regarding the initial management of cyanotic or duct-dependent infants with TOF and adverse risk factors. While repair can and has been performed in these patients, it is associated with increased morbidity.We review the effectiveness of right ventricular outflow tract (RVOT) stenting in the symptomatic young infant with TOF.Clinical, echocardiographic, angiographic and haemodynamic data were reviewed for nine patients who underwent 11 RVOT stenting procedures from October 1994 to August 2007.The pulmonary valve was deemed unsalvageable in all patients (median valve diameter 3.7 mm (range 2.7-4.2), Z-score -6.7 (range -9.7 to -5.4). RVOT stenting improved arterial oxygen saturation from a median of 73% (60-85%) to 94% (90-98%) (p = 0.008). Median Z-score for the left pulmonary artery increased from -4.9 (-7.8 to -2.4) before stent implantation to -1.5 (-4.2 to -0.2) (p = 0.02) before surgical repair. Median Z-score for the right pulmonary artery increased from -3.7 (-6.8 to -1.9) to -0.8 (-2.5 to 0.1) (p = 0.008). Median Nakata index increased from 56 mm(2)/m(2) (21-77) to 150 mm(2)/m(2) (123-231) (p = 0.008). There were no procedural complications. Six patients have undergone successful repair. There were no deaths.In the symptomatic young infant with TOF, stenting of the RVOT provides a safe and effective management strategy, improving arterial oxygen saturation and encouraging pulmonary artery growth.

    View details for DOI 10.1136/hrt.2007.135723

    View details for PubMedID 18332061

  • Implantation of drug-eluting stents for relief of obstructed infra-cardiac totally anomalous pulmonary venous connection in isomerism of the right atrial appendages. Cardiology in the young Wong, D. T., Yoo, S. J., Lee, K. J. 2008; 18 (6): 628-30


    We describe an infant with severe obstruction of infra-cardiac totally anomalous pulmonary venous connection associated with right isomerism, atrioventricular septal defect, pulmonary atresia, and multiple aortopulmonary collateral arteries. Implantation of a stent into the obstructed descending vertical vein provided effective palliation, with a dramatic increase in saturations of oxygen obviating the need for urgent high-risk surgery.

    View details for DOI 10.1017/S1047951108003120

    View details for PubMedID 18828956

  • Complete heart block associated with device closure of perimembranous ventricular septal defects. The Journal of thoracic and cardiovascular surgery Predescu, D., Chaturvedi, R. R., Friedberg, M. K., Benson, L. N., Ozawa, A., Lee, K. J. 2008; 136 (5): 1223-8


    The development of the Amplatzer Membranous VSD Occluder (AGA Medical Corp, Plymouth, Minn) for closure of the perimembranous ventricular septal defect has ameliorated many of the technical difficulties of previous devices. Application of this new technology requires comparative evaluation with the current standard of surgical repair. We report our experience of complete heart block associated with device closure of a large perimembranous ventricular septal defect with unequivocal indications for intervention.We performed a retrospective review of 20 patients between January 2003 and August 2005 who underwent perimembranous ventricular septal defect device closure, 18 with hemodynamically large shunts meeting the surgical criteria for intervention. The median age was 1.6 years (range, 0.5-16.2 years), and the median weight was 9.7 kg (range, 6.2-43 kg).Acute complete shunt occlusion was achieved in all patients. There were no acute procedural complications. The median follow-up time was 23.1 months (range, 1-37.8 months). Four (22%) had complete heart block at 17 days, 4.2 months, 8.8 months, and 37.5 months after implantation, respectively. No risk factors were identified for development of complete heart block, including age, weight, trisomy 21, preceding conduction abnormalities, perimembranous ventricular septal defect size related to body surface area or device size, and progressive device flattening.Device closure of large perimembranous ventricular septal defects in infants and children with the Amplatzer Membranous VSD Occluder resulted in excellent closure rates but an unacceptably high rate of complete heart block.

    View details for DOI 10.1016/j.jtcvs.2008.02.037

    View details for PubMedID 19026807

  • Borderline hypoplasia of the left ventricle in neonates: insights for decision-making from functional assessment with magnetic resonance imaging. The Journal of thoracic and cardiovascular surgery Grosse-Wortmann, L., Yun, T. J., Al-Radi, O., Kim, S., Nii, M., Lee, K. J., Redington, A., Yoo, S. J., van Arsdell, G. 2008; 136 (6): 1429-36


    We sought to compare the usefulness of echocardiography and magnetic resonance imaging in neonates with a borderline small left ventricle.The preoperative magnetic resonance and echocardiography studies of 20 consecutive patients (mean age 10 +/- 9 days) undergoing magnetic resonance imaging were analyzed. The diagnoses were aortic stenosis (n = 3), hypoplastic left heart complex (n = 12), and unbalanced atrioventricular septal defect (n = 5). The magnetic resonance imaging protocol included ventricular volumetry, flow measurements, and angiography. Potential left ventricular volumes, assuming an ideal geometric shape, were calculated by mathematically "unfolding" the compressed left ventricle.Left ventricular end-diastolic volume was 16.0 +/- 7.0 mL/m(2) of body surface area by echocardiography and 33.5 +/- 15.5 mL/m(2) by magnetic resonance imaging. Echocardiography consistently underestimated left ventricular volume and did not correlate with magnetic resonance. Of all echocardiographic parameters, mitral valve z-score was the best predictor of left ventricular end-diastolic volume by magnetic resonance (r = 0.77; P = .02). The average potential volume increase was 8.8% for aortic stenosis, 35.0% for atrioventricular septal defect and 23.0% for hypoplastic left heart complex patients. Aortic valve diameter did not correlate with flow volume in the ascending aorta. Sixteen (80%) of 20 patients underwent biventricular repair, without early mortality. Of these, only 5 (31.3%) had a preoperative left ventricular end-diastolic volume of more than 20 mL/m(2) by echocardiography.Magnetic resonance imaging is feasible in neonates with borderline left ventricular hypoplasia. Echocardiography does not accurately measure left ventricular hypoplasia in these patients and may unfairly preclude some patients from a biventricular repair in whom magnetic resonance is reassuring.

    View details for DOI 10.1016/j.jtcvs.2008.04.027

    View details for PubMedID 19114185

  • Outcome and growth potential of left heart structures after neonatal intervention for aortic valve stenosis. Journal of the American College of Cardiology Han, R. K., Gurofsky, R. C., Lee, K. J., Dipchand, A. I., Williams, W. G., Smallhorn, J. F., McCrindle, B. W. 2007; 50 (25): 2406-14


    The purpose of this study was to determine trends of growth of left heart structures after intervention for neonatal aortic valve stenosis.The growth potential of left heart structures in neonatal aortic valve stenosis after relief of obstruction might influence risk for subsequent outcomes.From 1994 to 2004, 53 patients underwent neonatal (< or =30 days old) balloon aortic valve dilation. Factors associated with time-related outcomes (death, reintervention, aortic valve replacement) and longitudinal changes in normalized left heart dimensions were sought.The median age at intervention was 3.5 days (range 1 to 30 days). During a median follow-up of 3.2 years ranging up to 10.9 years, there were 31 reinterventions on the aortic valve in 21 (40%) patients and 7 deaths (13%). The presence of moderate or severe left ventricular (LV) endocardial fibroelastosis was the only independent predictor for time-related mortality (hazard ratio 22.1; p = 0.004), and a smaller initial aortic valve annulus z-score was a significant independent predictor for aortic valve replacement (hazard ratio 0.63 per 1-U change; p = 0.007). Aortic valve annulus, aortic sinus, and LV dimension z-scores significantly increased over time, whereas mitral valve z-scores remained below normal. The structure's initial z-score and concomitant size of other left heart structures were significant independent factors associated with subsequent z-scores.There is potential catch-up growth of the aortic valve and LV over time for neonates after intervention for aortic valve stenosis. However, the continued hypoplasia of the mitral valve warrants further consideration in the long-term management of these patients.

    View details for DOI 10.1016/j.jacc.2007.07.082

    View details for PubMedID 18154967

  • Neonatal rhabdomyoma causing right ventricular inflow obstruction with duct-dependent pulmonary blood flow: successful stenting of PDA. Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions Ilina, M. V., Jaeggi, E. T., Lee, K. J. 2007; 69 (6): 881-5


    We describe an infant with the antenatal diagnosis of a large intracardiac rhabdomyoma causing tricuspid inflow obstruction. Postnatal cyanosis and arterial hypoxemia prompted commencement of intravenous prostaglandin E1 with immediate improvement in saturations. Clinical and genetic testing confirmed diagnosis of tuberous sclerosis. To secure ductal patency, two tandem coronary stents were implanted via an antegrade approach. Several episodes of long RP atrio-ventricular re-entrant tachycardia were observed. At 7(1/2) months of age, the tumor was no longer obstructive to tricuspid inflow, ductal flow was highly restrictive and there was no recurrence of supraventricular tachycardia.

    View details for DOI 10.1002/ccd.21064

    View details for PubMedID 17436271

  • ABO-incompatible heart transplantation in infants. The New England journal of medicine West, L. J., Pollock-Barziv, S. M., Dipchand, A. I., Lee, K. J., Cardella, C. J., Benson, L. N., Rebeyka, I. M., Coles, J. G. 2001; 344 (11): 793-800


    Transplantation of hearts from ABO-incompatible donors is contraindicated because of the risk of hyperacute rejection mediated by preformed antibodies in the recipient to blood-group antigens of the donor. This contraindication may not apply to newborn infants, who do not yet produce antibodies to T-cell-independent antigens, including the major blood-group antigens.We studied 10 infants 4 hours to 14 months old (median, 2 months) who had congenital heart disease or cardiomyopathy and who received heart transplants from donors of incompatible blood type between 1996 and 2000. Serum isohemagglutinin titers were measured before and after transplantation. Plasma exchange was performed during cardiopulmonary bypass; no other procedures for the removal of antibodies were used. Standard immunosuppressive therapy was given, and rejection was monitored by means of endomyocardial biopsy. The results were compared with those in 10 infants who received heart transplants from ABO-compatible donors.The overall survival rate among the 10 recipients with ABO-incompatible donors was 80 percent, with 2 early deaths due to causes presumed to be unrelated to ABO incompatibility. The duration of follow-up ranged from 11 months to 4.6 years. Two infants had serum antibodies to antigens of the donor's blood group before transplantation. No hyperacute rejection occurred; mild humoral rejection was noted at autopsy in one of the infants with antibodies. No morbidity attributable to ABO incompatibility has been observed. Despite the eventual development of antibodies to antigens of the donor's blood group in two infants, no damage to the graft has occurred. Because of the use of ABO-incompatible donors, the mortality rate among infants on the waiting list declined from 58 percent to 7 percent.ABO-incompatible heart transplantation can be performed safely during infancy before the onset of isohemagglutinin production; this technique thus contributes to a marked reduction in mortality among infants on the waiting list.

    View details for DOI 10.1056/NEJM200103153441102

    View details for PubMedID 11248154

  • Restoration of aortopulmonary shunt patency. The American journal of cardiology Lee, K. J., Humpl, T., Hashmi, A., Nykanen, D. G., Williams, W. G., Benson, L. N. 2001; 88 (3): 325-8

    View details for DOI 10.1016/s0002-9149(01)01654-x

    View details for PubMedID 11472721

  • Clinical outcomes of acute myocarditis in childhood. Heart (British Cardiac Society) Lee, K. J., McCrindle, B. W., Bohn, D. J., Wilson, G. J., Taylor, G. P., Freedom, R. M., Smallhorn, J. F., Benson, L. N. 1999; 82 (2): 226-33


    To describe clinical outcomes of a paediatric population with histologically confirmed lymphocytic myocarditis.A retrospective review between November 1984 and February 1998.A major paediatric tertiary care hospital.36 patients with histologically confirmed lymphocytic myocarditis.Survival, cardiac transplantation, recovery of ventricular function, and persistence of dysrhythmias.Freedom from death or cardiac transplantation was 86% at one month and 79% after two years. Five deaths occurred within 72 hours of admission, and one late death at 1.9 years. Extracorporeal membrane oxygenation support was used in four patients, and three patients underwent heart replacement. 34 patients were treated with intravenous corticosteroids. In the survivor/non-cardiac transplantation group (n = 29), the median follow up was 19 months (range 1.2-131.6 months), and the median period for recovery of a left ventricular ejection fraction to > 55% was 2.8 months (range 0-28 months). The mean (SD) final left ventricular ejection and shortening fractions were 66 (9)% and 34 (8)%, respectively. Two patients had residual ventricular dysfunction. No patient required antiarrhythmic treatment. All survivors reported no cardiac symptoms or restrictions in physical activity.Our experience documents good outcomes in paediatric patients presenting with acute heart failure secondary to acute lymphocytic myocarditis treated with immunosuppression. Excellent survival and recovery of ventricular function, with the absence of significant arrhythmias, continued cardiac medications, or restrictions in physical activity were the normal outcomes.

    View details for DOI 10.1136/hrt.82.2.226

    View details for PubMedID 10409542

    View details for PubMedCentralID PMC1729152