Publications by authors named "Timothy Colen"

Purpose: Right atrial volume (RAV) and function have proven prognostic value in the assessment of cardiac disease and may be more accurately assessed using three-dimensional echocardiography (3DE). Normal 3DE reference values for the right atrial (RA) volume and function in healthy children have not yet been published. Furthermore, current methods of indexing cardiac measurements to body surface area (BSA) alone may be insufficient.

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Objectives: The aim of this study was to evaluate the mid-term outcomes after the repair of aortic arch using a standard patch augmentation technique.

Methods: The study included all patients who underwent repair of a hypoplastic/interrupted aortic arch (IAA) in a single institute from June 2012 to December 2019 by a standardized patch augmentation (irrespective of concomitant intra-cardiac lesions). End points evaluated were reintervention for arch obstruction and persistent/new-onset hypertension.

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Background: Three-dimensional echocardiography (3DE) evaluation of right ventricular (RV) volumes and ejection fraction (EF) is increasingly used for clinical serial assessments and management in children. This study aims to generate sex-specific reference values and z-score equations for RV volumetric parameters, independent of age and body size indices, derived from multiple populations across North America.

Methods: We prospectively recruited 455 healthy children (ages 0 to 18 years) from 5 centres.

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Branch pulmonary artery (PA) stenosis due to ductus arteriosus (DA) tissue (DA-PS) contributes to the morbidity associated with pulmonary atresia (PAtr). We sought to identify preoperative echocardiographic features predictive of DA-PS. Patients consecutively encountered with PAtr and a DA-dependent pulmonary circulation at birth who underwent intervention in our program over a 5-year period were identified and records reviewed.

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Background: Tricuspid regurgitation (TR) in hypoplastic left heart syndrome (HLHS) is associated with morbidity and mortality. TR mechanisms and the impact of tricuspid valve repair (TVR) are unclear. We examined HLHS TR mechanisms, TVR's impact on tricuspid valve (TV), and features of poor TVR durability.

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Background: Tricuspid valve regurgitation (TR) is a risk factor for morbidity and mortality in children with hypoplastic left heart syndrome (HLHS). Surgical tricuspid valve (TV) repair is common, but durable repair remains challenging. The aim of this study was to examine mechanisms of TR requiring surgery, features associated with unsuccessful repair, and TV changes after surgical repair.

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Background: The aims of this study were to investigate the dynamic changes in the vena contracta (VC) and proximal isovelocity surface area (PISA) through systole in patients with hypoplastic left heart syndrome and tricuspid regurgitation and to identify the stage of systole (early, mid, or late) in which VC and PISA radius are optimal.

Methods: Twenty-eight patients with hypoplastic left heart syndrome were prospectively studied using continuous two-dimensional (2D) and three-dimensional (3D) echocardiography. Two-dimensional VC width, 3D VC area, and PISA radii (2D and 3D) were measured frame by frame throughout systole.

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Background: Twenty-five percent of patients with hypoplastic left heart syndrome (HLHS) require tricuspid valve (TV) repair. The location of tricuspid regurgitation (TR) is important in determining the type of repair performed. Studies using three-dimensional echocardiography (3DE) have reported a high incidence of error on two-dimensional echocardiography (2DE) for the identification of TV leaflets.

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Right ventricular (RV) remodeling in hypoplastic left heart syndrome (HLHS) begins prenatally and continues through staged palliations. However, it is unclear if the most marked observed remodeling post-Norwood is secondary to cardiopulmonary bypass (CPB) exposure or if it is an adaptation intrinsic to the systemic RV. This study aims to determine the impact of CPB on RV remodeling in HLHS.

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Heart conditions in which the tricuspid valve (TV) faces either increased volume or pressure stressors are associated with premature valve failure. Mechanistic studies to improve our understanding of the underlying pathophysiology responsible for the development of premature TV failure are lacking. Due to the inability to conduct these studies in humans, an animal model is required.

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Background: Fetal Ebstein's anomaly and tricuspid valve dysplasia (EA/TVD) are associated with high perinatal mortality relative to pulmonary atresia with intact ventricular septum (PAIVS), despite both requiring redistribution of the cardiac output (CO) to the left ventricle (LV). LV dysfunction is suspected to contribute to adverse outcomes in EA/TVD.

Objective: We sought to examine global and segmental LV function in fetal EA/TVD with comparison to normal controls and PAIVS.

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Background: Accurate fetal arrhythmia (FA) diagnosis is key for effective management. Currently, FA assessment relies on standard echocardiography-based techniques (M mode and spectral Doppler), which require adequate fetal position and cursor alignment to define temporal relationships of mechanical events. Few data exist on the application of color Doppler tissue imaging (c-DTI) in FA assessment.

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Article Synopsis
  • This study investigates the role of right atrial (RA) and right ventricular (RV) dynamics in predicting outcomes for children with pulmonary arterial hypertension (PAH).
  • Researchers analyzed clinical data from 57 children, focusing on echocardiographic measurements to assess RA active emptying fraction (EaF) and RV fractional area change (FAC).
  • Results indicated that specific RA and RV metrics, particularly RA EaF ≥60% and RVFAC <25%, are strong indicators of clinical worsening and mortality, suggesting their potential as important monitoring tools for affected children.
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Background: Ventricular dysfunction is associated with increased morbidity and mortality in children with hypoplastic left heart syndrome. The aim of this study was to assess the diagnostic performance of conventional and speckle-tracking echocardiographic measures of right ventricular (RV) function before bidirectional cavopulmonary anastomosis palliation in predicting death or need for heart transplantation (HTx).

Methods: RV fractional area change (RVFAC) and longitudinal and circumferential strain and strain rate (SR) were measured in 64 prospectively recruited patients with hypoplastic left heart syndrome from echocardiograms obtained before bidirectional cavopulmonary anastomosis surgery.

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Background: Tricuspid regurgitation (TR) is an important risk factor for morbidity and mortality in hypoplastic left heart syndrome (HLHS), yet the evolution of tricuspid valve (TV) dysfunction in HLHS is poorly understood. This study sought to examine changes in TV function in HLHS between the first two stages of surgical palliation and to determine the mechanism of TR at the time of stage two surgery-bidirectional cavopulmonary anastomosis (BCPA).

Methods: We prospectively investigated 44 infants at two time points-prior to Norwood-Sano (T1 - median age 5.

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Background: In severe right heart obstruction (RHO), redistribution of cardiac output to the left ventricle (LV) is well tolerated by the fetal circulation. Although the same should be true of severely regurgitant tricuspid valve disease (rTVD) with reduced or no output from the right ventricle, affected fetuses more frequently develop hydrops or suffer intrauterine demise. We hypothesized that right atrium (RA) function is altered in rTVD but not in RHO, which could contribute to differences in outcomes.

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Background: Single right ventricles (SRV) are postulated to be disadvantaged compared with single left ventricles (SLV). We compared the evolution of SRV versus SLV function during infancy using conventional measures and speckle-tracking echocardiography (STE). We hypothesized that the SRV is mechanically disadvantaged during early infancy.

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We sought to describe the prenatal features and postnatal outcomes of the "criss-cross heart" (CCH) with crossing atrioventricular connections as encountered in 5 cases and to review the literature regarding fetal diagnoses of this lesion. We reviewed the clinical history and fetal echocardiograms of 5 patients with a diagnosis of CCH encountered in our institution from 2010 to 2015. Affected pregnancies were identified through the University of Alberta fetal cardiology database.

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Echocardiography has developed as an imaging technology over 60 years to become the mainstay for investigating heart disease, providing invaluable structural and functional information. In the last 20 years, 3-dimensional echocardiography (3DE) has emerged as an adjunct to 2-dimensional echocardiography in adult and congenital heart disease. Early work with 3-dimensional imaging of the mitral valve describing normal annular shape and function significantly changed the understanding of mitral valve dynamics.

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Objective: Significant atrioventricular valve regurgitation (AVVR) increases mortality in patients with unbalanced atrioventricular septal defects (uAVSDs) and a single ventricle. We tested the hypothesis that abnormal leaflet tethering is associated with progressive AVVR in patients with a single ventricle with uAVSD.

Methods: We retrospectively reviewed the initial presentation and prebidirectional cavopulmonary anastamosis echocardiograms of 46 consecutive patients with uAVSD with single ventricle palliation.

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Background: Our purpose was to test the following hypotheses: (1) patients with hypoplastic left heart syndrome who develop significant tricuspid regurgitation (TR) or require tricuspid valve (TV) surgery in the medium term have detectable TV abnormalities by 3-dimensional echocardiography (3DE) prestage 1 palliation and (2) TR is associated with reduced survival and increased TV intervention.

Methods And Results: Infants were prospectively studied with 3DE and 2DE prestage 1 and followed up for the end points of TR, TV surgery, transplantation, or death. From prestage 1 3DE, spatial coordinates of TV annulus and leaflets were extracted; annulus size, leaflet area, prolapse volume, tethering volume, bending angle, and papillary muscle angle were measured.

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Background: The long-term prognosis of hypoplastic left heart syndrome is limited by progressive right ventricular dysfunction. The aim of this study was to determine the trends in single right ventricular systolic function between staged palliative surgeries using speckle-tracking and conventional echocardiography.

Methods: There were 76 patients with functionally single right ventricles at the (1) pre-Norwood (n = 26), (2) pre-bidirectional cavopulmonary anastomosis (BCPA; n = 19), (3) pre-Fontan (n = 16), and (4) post-Fontan (n = 15) stages, compared with 30 controls of similar ages.

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Congenital mitral valve abnormalities are rare and cause mitral stenosis, regurgitation, or a combination of the two. Three-dimensional echocardiography has provided new insight into the structure and function of both normal and abnormal mitral valves. Three-dimensional imaging permits accurate anatomic diagnosis and enhances two-dimensional echocardiographic data.

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Background: Long-term survival after atrioventricular septal defect repair is excellent; however, postoperative left atrioventricular valve regurgitation affects morbidity and quality of life. Left atrioventricular valve regurgitation is the most common reason for reoperation after repair and it is critical that clinicians recognize pathologic mechanisms pre-repair.

Methods: In this single-center experience, we identified a pattern of left atrioventricular valve abnormality in 5 cases presenting for routine surgical repair between 1 month and 24 years of age.

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Background: Mechanisms of mitral valve regurgitation after atrioventricular septal defect repair are unclear.

Methods: To gain further insight into mitral valve regurgitation, real-time three-dimensional echocardiography was performed in 53 patients after atrioventricular septal defect repair (30 partial and 23 complete) and 40 controls. Mitral valve {x, y, z} coordinates from the annulus, leaflet surface, papillary muscle, and chordal attachments were recorded.

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