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Dive into the research topics where Gary Webb is active.

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Featured researches published by Gary Webb.


American Journal of Cardiology | 2000

Mode of death in adults with congenital heart disease

Erwin Oechslin; David A Harrison; Michael S Connelly; Gary Webb; Samuel C. Siu

An increasing number of patients with congenital heart disease (CHD) are entering adulthood. Although prior studies have focused on the causes of death in the pediatric population, the modes of death for adults with CHD have not been well defined. In a cross-sectional study performed on a population of 2,609 consecutive adults assessed at a CHD specialty clinic, there were adequate information available in 197 of 199 deceased patients. Mean age at death was 37 +/- 15 years. Mortality was highest in patients with congenitally corrected transposition of the great arteries (26%), tricuspid atresia (25%), and univentricular connection (23%). Youngest mean age at death was observed in patients with tricuspid atresia (27 +/- 5 years), complete transposition of the great arteries (27 +/- 7 years), pulmonary atresia (27 +/- 6 years), and aortic coarctation (29 +/- 6 years). Sudden death (26%) was the most common cause of death followed by progressive heart failure (21%) and perioperative death (18%). Postmortem examinations were performed in 77 of 197 deceased patients (39%) and provided incremental data on the mechanism of death in 22% of autopsies. Thus, the 3 major causes of death in the growing population of adults with CHD are sudden, perioperative, and progressive heart failure.


Journal of the American College of Cardiology | 2002

Left ventricular dysfunction is a risk factor for sudden cardiac death in adults late after repair of tetralogy of fallot

Akash Ghai; Candice K. Silversides; Louise Harris; Gary Webb; Samuel C. Siu; Judith Therrien

OBJECTIVESnThe purpose of this study was to determine if left ventricular (LV) systolic dysfunction was also a predictor of sudden cardiac death (SCD) in adults late after repair of tetralogy of Fallot (TOF).nnnBACKGROUNDnPrevious studies looking at risk factors for SCD in adults with repair of TOF have focused on the right ventricle (RV).nnnMETHODSnA retrospective chart review of patients assessed at the Toronto Congenital Cardiac Centre for Adults was performed. Twelve adult patients with repaired TOF and SCD were identified (SCD group). A total of 125 living adult patients with repaired TOF were randomly selected for comparison (control group).nnnRESULTSnPatients with SCD were more likely to exhibit moderate or severe pulmonary regurgitation (92% vs. 51%, p = 0.02), have a history of sustained ventricular tachycardia (42% vs. 6%, p < 0.01), and have a QRS > or =180 ms (56% vs. 13%, p = 0.02). Moderate or severe LV systolic dysfunction was also significantly more common in patients with SCD than in the control group (42% vs. 9%, p < 0.01) with a positive predictive value of 29%. The combination of moderate or severe LV systolic dysfunction and QRS > or =180 ms had a positive and negative predictive value for SCD of 66% and 93%, respectively.nnnCONCLUSIONSnModerate or severe LV systolic dysfunction is significantly more common in adult patients with repaired TOF and SCD. The combination of QRS > or =180 ms and significant LV systolic dysfunction has high positive and negative predictive value for SCD. The implication of the role of prophylactic antiarrhythmic implantable cardiac defibrillator insertion in these patients needs further elucidating.


American Journal of Medical Genetics Part A | 2005

Clinical features of 78 adults with 22q11 Deletion Syndrome.

Anne S. Bassett; Eva W.C. Chow; Janice Husted; Rosanna Weksberg; Oana Caluseriu; Gary Webb; Michael A. Gatzoulis

22q11 Deletion Syndrome (22q11DS) is a common microdeletion syndrome with multisystem expression. Phenotypic features vary with age, ascertainment, and assessment. We systematically assessed 78 adults (36 M, 42 F; mean age 31.5, SD 10.5 years) with a 22q11.2 deletion ascertained through an adult congenital cardiac clinic (nu2009=u200935), psychiatric‐related sources (nu2009=u200939), or as affected parents of subjects (nu2009=u20094). We recorded the lifetime prevalence of features requiring attention, with 95% confidence intervals (CI) not overlapping zero. Subtle learning difficulties, hypernasality and facial gestalt were not included. We investigated ascertainment effects using non‐overlapping subgroups ascertained with tetralogy of Fallot (nu2009=u200931) or schizophrenia (nu2009=u200931). Forty‐three features met inclusion criteria and were present in 5% or more patients, including several of later onset (e.g., hypothyroidism, cholelithiasis). Number of features per patient (median 9, range 3–22) correlated with hospitalizations (Pu2009=u20090.0002) and, when congenital features were excluded, with age (Pu2009=u20090.02). Adjusting for ascertainment, 25.8% (95% CI, 9.5–42.1%) of patients had cardiac anomalies and 22.6% (95% CI, 7.0–38.2%) had schizophrenia. Ascertainment subgroups were otherwise similar in median number and prevalence of features. Non‐characteristic features are common in 22q11DS. Adjusting for ascertainment effects is important. Many treatable conditions may be anticipated and features may accumulate over time. The results have implications for clinical assessment and management, genetic counseling and research into pathophysiological mechanisms.


The Journal of Thoracic and Cardiovascular Surgery | 2000

Dilation of the pulmonary autograft after the ross procedure

Tirone E. David; Ahmad Omran; Joan Ivanov; Susan Armstrong; Mauro de Sa; Brian Sonnenberg; Gary Webb

OBJECTIVEnDilation of pulmonary autograft after the Ross procedure is being recognized with increasing frequency. This study was undertaken to examine the extent of this problem and factors that may be associated with it.nnnMETHODSnThe clinical, operative, and echocardiographic data of 118 patients who underwent the Ross procedure were reviewed. The mean age of 79 men and 39 women was 34 +/- 9 years, range 17 to 57 years. Bicuspid or other congenital aortic valve disease was present in 81% of patients. The pulmonary autograft was sutured as a valve in the subcoronary position in 2 patients, as a root inside of the aortic root in 45, and was used for complete aortic root replacement in 71. Teflon felt was not used to buttress the proximal or the distal anastomosis of the pulmonary autograft. The diameters of the sinuses of Valsalva, aortic anulus, and sinotubular junction were measured early and late after the operation with echocardiography. The mean follow-up was 44 months.nnnRESULTSnThe diameter of the sinuses of Valsalva increased from 31.4 +/- 0.4 mm to 33.7 +/- 0.5 mm (P =.01). Analysis of covariance revealed a significant change over time in this diameter, as well as a difference between operative techniques, with replacement of the aortic root being associated with a higher risk of dilation (P =. 0006). In 13 patients the diameter ranged from 40 to 51 mm. The diameter of the aortic anulus decreased in most patients and increased in 15, but there was no interaction between these changes and the operative technique. The diameter of the sinotubular junction increased in patients who had aortic root replacement and decreased in patients who had aortic root inclusion (P =.007). Moderate aortic insufficiency developed in 7 patients, and 3 required replacement of the pulmonary autograft. All patients with moderate aortic insufficiency had dilation of the aortic anulus and/or sinotubular junction.nnnCONCLUSIONSnDilation of the pulmonary autograft after the Ross procedure may occur because of an intrinsic abnormality of the pulmonary root in patients with congenital aortic valve disease. The technique of aortic root replacement is associated with a higher risk of dilation of the sinuses of Valsalva and sinotubular junction than the technique of aortic root inclusion.


European Journal of Cardio-Thoracic Surgery | 2009

Late risk of outcomes for adults with repaired tetralogy of Fallot from an inception cohort spanning four decades

Edward J. Hickey; Gruschen Veldtman; Timothy J. Bradley; Aungkana Gengsakul; Cedric Manlhiot; William G. Williams; Gary Webb; Brian W. McCrindle

BACKGROUNDnAdult survivors with tetralogy of Fallot constitute a growing population with congenital heart disease. We investigated an inception cohort who underwent surgical repair. We aimed to characterize late hazard or risk for death, and determine the time-related risk of late re-operation and pulmonary valve replacement (PVR).nnnMETHODSnAll children (n=1181) with tetralogy of Fallot born before 1984 who underwent surgical repair at our institution were included. Follow-up (median 20 years after repair) was obtained from 2003 to 2006 via chart review, clinic consultation and telephone interview. Outcomes were analyzed using parametric and competing risks techniques with bagging.nnnRESULTSnCorrective repair performed from 1960 to 1998 included transannular patch (n=370), right ventricular outflow tract patch (n=326), no patch (n=333) and right ventricular-pulmonary artery conduit (n=54). Overall, 85+/-1% survived to adulthood (age >18 years). Thirty years after repair, survival was 80+/-1%, instantaneous hazard or risk of death was 0.5+/-0.07% per year and half of survivors had undergone surgical re-operation. Surgical era of repair did not influence late risk of death. Therefore, with early surgical mortality <2% since 1985, 20-year survival has improved to 94+/-1%. If trends in late risks match those of the earliest repairs, 40-year survival will be approximately 90% for children repaired in the modern era. Pulmonary atresia variant (n=88) was associated with three-fold higher late risk of death than classic tetralogy of Fallot (n=1069). Presence of associated branch pulmonary artery stenosis or atrioventricular septal defects conferred a less optimal late prognosis. Risk of PVR was low, constant (0.8% per year) and independent of surgical era. Both pulmonary atresia and absent pulmonary valve (n=15) variants were associated with higher risk of late re-operation or PVR. Survival after re-operation or PVR (88+/-3% and 94+/-3% at 20 years, respectively) was excellent.nnnCONCLUSIONSnSurgical progress has not influenced late risks for death, re-operation or PVR in adults with repaired tetralogy of Fallot. Instead, reduction of early surgical mortality to <2% is responsible for excellent late survival >90% overall. The constant risk of PVR is low and independent of repair type. Baseline morphologic features are important determinants of late outcome.


Journal of the American College of Cardiology | 2001

Outcomes of late atrial tachyarrhythmias in adults after the Fontan operation

Akash Ghai; Louise Harris; David A Harrison; Gary Webb; Samuel C. Siu

OBJECTIVESnThe purpose of this study was to compare the clinical and echocardiographic features of adults who developed atrial tachyarrhythmias (ATs) late after a Fontan procedure with those who have remained free of arrhythmias.nnnBACKGROUNDnAtrial tachyarrhythmias are a frequent complication of the Fontan operation. However, the outcomes in adult patients with AT who have had the Fontan operation have not been well defined.nnnMETHODSnWe reviewed the outcomes of 94 consecutive patients who underwent the Fontan operation between 1977 and 1994 and were followed as adults at the University of Toronto Congenital Cardiac Centre for Adults. Sixty patients had an atriopulmonary connection, 21 patients had an atrioventricular connection, and 13 patients received a lateral tunnel connection.nnnRESULTSnThirty-nine patients (41%) had sustained AT (atrial fibrillation, atrial flutter or supraventricular tachycardia) after their Fontan procedure. Compared with patients who did not develop AT, those who did were more likely to develop heart failure (46% vs. 13%, p = 0.003) and right atrial thrombus (31% vs. 4%, p = 0.006), exhibit left atrial enlargement (mean [+/-SD] diameter: 44 +/- 10 vs. 37 +/- 9 mm, p = 0.002), exhibit right atrial enlargement (mean [+/-SD] volume: 139 +/- 149 vs. 76 +/- 54 ml, p = 0.040) and have moderate-to-severe systemic valve regurgitation (31% vs. 7%, p = 0.010). The mean survival time was not significantly different between the arrhythmia group and the arrhythmia-free group (21.2 +/- 1.3 and 18.0 +/- 0.7 years, respectively; p = 0.900).nnnCONCLUSIONSnSystemic atrioventricular valvular regurgitation and biatrial enlargement are commonly observed in patients who develop AT after the Fontan procedure. These patients are more likely to develop right atrial thrombus and heart failure.


The Annals of Thoracic Surgery | 2002

Aortic valve-sparing operations in patients with aneurysms of the aortic root or ascending aorta.

Tirone E. David; Joan Ivanov; Susan Armstrong; Christopher M. Feindel; Gary Webb

BACKGROUNDnAortic valve-sparing operations are an alternative to aortic root replacement in patients with aortic root aneurysms, or aortic valve replacement and supracoronary replacement of the ascending aorta in patients with ascending aorta aneurysms and dilated sinotubular junctions with consequent aortic insufficiency.nnnMETHODSnFrom 1988 to 2001, 230 patients underwent aortic valve-sparing operations for aortic root aneurysms (151 patients) or ascending aortic aneurysms with aortic insufficiency (79 patients). Two types of aortic valve-sparing operations were performed in patients with aortic root aneurysms: reimplantation of the aortic valve and remodeling of the aortic root. Mean follow-up was 3.8 +/- 2.8 years.nnnRESULTSnPatients with aortic root aneurysms were younger, had less severe aortic insufficiency, less extensive vascular disease, and better left ventricular function than patients with ascending aorta aneurysms. The 8-year survival was 83% +/- 5% for the first group and 36% +/- 14% for the second. The freedom from aortic valve reoperation at 8 years was 99% +/- 1% for the first group and 97% +/- 2% for the second. In patients who had aortic root aneurysms, 3 developed severe aortic insufficiency (AI), and 15 developed moderate AI, for an 8-year freedom from significant AI of 67% +/- 7%. But freedom from AI was 90% +/- 3% after the technique of reimplantation, and 55% +/- 6% after the technique of remodeling (p = 0.02). In patients with ascending aortic aneurysms, the freedom from AI greater than 2+ at 8 years was 67% +/- 11%.nnnCONCLUSIONSnThe long-term results of aortic valve sparing for aortic root aneurysms are excellent, and reimplantation of the aortic valve may provide a more stable repair of the aortic valve than remodeling of the aortic root.


Journal of the American College of Cardiology | 2001

Right ventricular form and function after percutaneous atrial septal defect device closure

Veldtman G; Vanessa Razack; Samuel Siu; Hassan El-Hajj; Fiona Walker; Gary Webb; Leland N. Benson; Peter R. McLaughlin

OBJECTIVESnWe sought to assess the right hearts response to percutaneous device closure of moderate sized atrial septal defects (ASDs) in adults over a one-year follow-up period.nnnBACKGROUNDnPercutaneous ASD device closure is a safe and effective means of reducing or eliminating interatrial shunting. The response of the adults right heart to device closure is incompletely understood.nnnMETHODSnForty consecutive patients had 40 device implantations (32 with the CardioSeal implant and 8 with the Amplatzer device). The patients were assessed with echocardiography, chest radiography and electrocardiography before the procedure and at 1, 6 and 12 months.nnnRESULTSnThe mean ASD size was 13+/-4 mm, and the device size ranged from 33 to 40 mm for CardioSeal and 12 to 36 mm for Amplatzer. At one month, heart size (49% vs. 46%), four-chamber right ventricular (RV) size (45 vs. 41 mm), paradoxical septal motion (60% vs. 5%), QRS duration (125 vs. 119 ms), PR interval (181 vs. 155 ms) and echocardiographically determined pulmonary artery systolic pressure decreased significantly and was maintained at 12-month follow-up. At six months, right atrial length decreased from 50 to 47 mm. At one year, 29% of patients had persistent RV enlargement.nnnCONCLUSIONSnRight heart morphology undergoes rapid improvement within one month of defect closure, with associated mechanoelectrical benefit. A small number of patients had persistent RV enlargement or pulmonary hypertension, or both, at one year. Our data support the application of transcatheter methods in achieving excellent hemodynamic and anatomic outcomes.


American Journal of Cardiology | 2001

Sustained atrial arrhythmias in adults late after repair of tetralogy of fallot

David A Harrison; Samuel C. Siu; Farrukh Hussain; Cynthia J MacLoghlin; Gary Webb; Louise Harris

We determined the prevalence of sustained atrial tachyarrhythmia (AT) in adults late after repair of tetralogy of Fallot (ToF) and examined its impact on subsequent heart failure, reoperation, and mortality. Ventricular arrhythmias are associated with increased morbidity and mortality in patients with repair of ToF. The clinical impact of AT in this population has not been established. A retrospective cohort study of 242 patients with repaired ToF identified 29 patients (prevalence of 12%) with sustained episodes of AT. Patients with repaired ToF but without sustained arrhythmia (n = 213) constituted a comparison group. Baseline characteristics and clinical outcomes in the 2 groups were compared. An echocardiographic analysis compared 15 patients with AT and 15 matched for age at operation and timing of echocardiography. The development of AT was associated with substantial morbidity including congestive heart failure, reoperation, subsequent ventricular tachycardia, stroke, and death (combined events, 20 of 29 patients [69%]). The rate of combined events (congestive heart failure, stroke, and deaths) in the 213 arrhythmia-free patients was 30% (64 of 213 patients). Event-free survival after repair was 18 +/- 2 years for the AT group and 28 +/- 1 years for the arrhythmia-free group (p < 0.001). Patients with AT were older at surgical repair (25 +/- 16 vs 10 +/- 9 years, p = 0.001), and at most recent assessment were aged 48 +/- 12 vs 32 +/- 10 years (p = 0.001). The AT group had a higher mean right atrial volume and proportion of significant pulmonary regurgitation than matched controls. The development of AT in the adult late after ToF repair identifies patients at risk and is associated with older age at repair, a higher frequency of hemodynamic abnormalities, and increased morbidity.


Journal of the American College of Cardiology | 2003

Prevalence of “silent” pulmonary emboli in adults after the Fontan operation ☆

Chetan Varma; Matthew R. Warr; Aaron Hendler; Narinder Paul; Gary Webb; Judith Therrien

OBJECTIVESnThe study was done to determine the prevalence of pulmonary emboli (PE) in asymptomatic adult Fontan patients and to identify the risk factors associated with PE.nnnBACKGROUNDnRight atrial thrombi and systemic thromboembolic complications have been reported after the Fontan procedure. However, the frequency of silent PE in this patient population is not known.nnnMETHODSnAll consecutive adult Fontan patients attending the adult congenital clinic over a six-month period underwent ventilation-perfusion (VQ) scanning and blood testing for thrombophilia tendency. If the VQ scan showed an intermediate or high probability for PE, a computerized tomography (CT) pulmonary angiogram was performed to confirm the presence of PE.nnnRESULTSnThirty patients (mean age 26 +/- 7 years, 57% men) were included in this study. Five (17%) adult Fontan patients had an intermediate or high probability for PE on VQ scan, all of which were confirmed on CT pulmonary angiography. No patient had a thrombophilia tendency. Pulmonary emboli were not present in any patients (30%) taking warfarin. Late age at time of Fontan operation (19 +/- 6 years vs. 11 +/- 6 years, p = 0.012) and type of Fontan anatomy (p = 0.001) were associated with increased risk of silent PE.nnnCONCLUSIONSnSeventeen percent of adult patients with Fontan procedure have clinically silent PE. The long-term hemodynamic implications of this with respect to Fontan attrition over time are unknown. Large randomized prospective studies looking at anticoagulation therapy in all Fontan patients are urgently needed.

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Samuel C. Siu

University Health Network

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Louise Harris

University Health Network

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