A5108220834- Advanced MRI Techniques and Applications
- Cardiac Imaging and Diagnostics
- Cardiac Arrhythmias and Treatments
- Cardiac electrophysiology and arrhythmias
- Electron Spin Resonance Studies
- Advanced NMR Techniques and Applications
- Acute Myocardial Infarction Research
- Atrial Fibrillation Management and Outcomes
- Cardiovascular Function and Risk Factors
- Cardiac Structural Anomalies and Repair
- Lanthanide and Transition Metal Complexes
- Medical Imaging Techniques and Applications
- Cardiac Arrest and Resuscitation
- Chemotherapy-induced cardiotoxicity and mitigation
- Cardiac pacing and defibrillation studies
- Silicon Nanostructures and Photoluminescence
- Religious Tourism and Spaces
- Solid-state spectroscopy and crystallography
- Coronary Interventions and Diagnostics
- Theology and Canon Law Studies
- Classical Antiquity Studies
- Thermal Radiation and Cooling Technologies
- Silicon and Solar Cell Technologies
- Atomic and Subatomic Physics Research
- Reformation and Early Modern Christianity
Sunnybrook Health Science Centre
2014-2025
Sunnybrook Research Institute
2015-2025
Sunnybrook Hospital
2011-2024
Thomas Jefferson University
2022
Sidney Kimmel Cancer Center
2022
Health Sciences Centre
2011-2021
Children's National
2014
University of Toronto
2012
Cleveland State University
1988
Highlights•hESC-CM transplantation partially remuscularizes the infarcted pig heart•hESC-CM recipients show frequent tachyarrhythmias at early time points•Graft-related arrhythmias arise from focal mechanisms rather than macro-reentrySummaryHuman embryonic stem cell-derived cardiomyocytes (hESC-CMs) considerable promise for regenerating injured hearts, and we therefore tested their capacity to stably engraft in a translationally relevant preclinical model, heart. Transplantation of immature...
Cancer cells have an imbalance in oxidation-reduction (redox) homeostasis. Understanding the precise mechanisms and impact of altered redox microenvironment on immunologic reaction to tumors is limited.We isolated exosomes from ovarian cancer through ultracentrifuge characterized by Western-blots Nanoparticle Tracking Analysis. 2D, 3D-coculture tumor model, 3D live cell imaging were used study interactions between cells, macrophages CD3 T vitro. The role exosomal miR-155-5p growth was...
Aims Impaired energy metabolism has been implicated in the pathogenesis of heart failure. Hyperpolarized 13 C magnetic resonance (MR), which C‐labelled metabolites are followed using MR imaging (MRI) or spectroscopy (MRS), enabled non‐invasive assessment pyruvate metabolism. We investigated hypothesis that if we serially examined a model failure hyperpolarized [ C]pyruvate with MR, profile vivo oxidation would change throughout course disease. Methods and results Dilated cardiomyopathy (DCM)...
Abstract Pathophysiological responses after acute myocardial infarction include edema, hemorrhage, and microvascular obstruction along with cellular damage. The in vivo evolution of these processes simultaneously throughout infarct healing has not been well characterized. purpose our study was to quantitatively monitor the time course mechanisms by MRI a porcine model infarction. Ten pigs underwent before coronary occlusion subgroups studied at day 2 weeks 1, 2, 4, 6 post‐infarction. Tissue...
13 C MR spectroscopy studies performed on hearts ex vivo and in following perfusion of prepolarized [1‐ C]pyruvate have shown that changes pyruvate dehydrogenase (PDH) flux may be monitored non‐invasively. However, to allow investigation Krebs cycle metabolism, the label must placed C2 position pyruvate. Thus, utilization either C1 or labeled as a tracer can only afford partial view cardiac metabolism health disease. If molecules were at both positions, then it would possible observe...
Background— Both intrinsic contrast (T 1 and T 2 relaxation the equilibrium magnetization) agent (gadolinium)–enhanced MRI are used to visualize evaluate acute radiofrequency ablation lesions. However, current methods imprecise in delineating lesion extent shortly after ablation. Methods Results— Fifteen lesions were created endocardium of 13 pigs. A multicontrast inversion recovery steady state free precession imaging method was delineate lesions, exploiting -weighted contrast. M o * maps...
Abstract Purpose Post‐contrast mapping has proven promising for automated scar segmentation in subjects without ICDs, but this not been implemented patients with ICDs. We introduce an cluster‐based thresholding method maps ICD present and compare it to manually tuned of synthetic LGE images standard present. Methods Seven swine received ischemia‐reperfusion myocardial infarction were imaged at 3 T 4–5 weeks post‐infarct ICD. Mapping‐based was performed using artifact‐corrected...
The type and extent of myocardial infarction encountered clinically is primarily determined by the severity initial ischemic insult. purpose study was to differentiate longitudinal fluctuations in remodeling mechanisms porcine myocardium following different insult durations. Animals ( N = 8) were subjected coronary balloon occlusion for either 90 or 45 min, followed reperfusion. Imaging performed on a 3 T MRI scanner between day‐2 week‐6 postinfarction with edema quantified T2, hemorrhage...
Radiofrequency (RF) ablation has become a mainstay of treatment for ventricular tachycardia, yet adequate lesion formation remains challenging. This study aims to comprehensively describe the composition and evolution acute left (LV) lesions using native-contrast cardiovascular magnetic resonance (CMR) during CMR-guided procedures. RF was performed an actively-tracked CMR-enabled catheter guided into LV 12 healthy swine create 14 lesions. T2 maps were acquired immediately post-ablation...
Myocardial hemorrhage is a frequent complication following reperfusion in acute myocardial infarction and predictive of adverse outcomes. However, it remains unsettled whether simply marker severe initial ischemic insult or directly contributes to downstream damage. Our objective was evaluate the contribution towards inflammation, microvascular obstruction infarct size novel porcine model hemorrhagic using cardiovascular magnetic resonance (CMR).
Identification of viable slow conduction zones manifested by abnormal local potentials is integral to catheter ablation ventricular tachycardia (VT) sites. The relationship between contrast patterns in cardiovascular magnetic resonance (CMR) and electrical mapping not well characterized. purpose this study was identify regions isolated, late fractionated diastolic sinus rhythm controlled-paced post-infarct animals relative detected gadolinium enhancement CMR (LGE-CMR). Using a real-time...
Spatially resolved images of hyperpolarized 13 C substrates and their downstream products provide insight into real‐time metabolic processes occurring in vivo. Recently, pyruvate has been used to characterize vivo cardiac metabolism the rat pig, but accurate reproducible measurements remain challenging due limited period available for imaging as well physiological motion. In this article, time‐resolved cardiac‐ respiratory‐gated [1‐ C] pyruvate, lactate, bicarbonate heart are acquired...
Abstract Left ventricular remodeling as a result of acute myocardial infarction (AMI) is associated with significant morbidity, leading to cardiovascular dysfunction, disability, and death. Despite successful revascularization, coronary vasodilatory dysfunction has been shown in infarcted remote myocardium patients following AMI. Our study explored the utility T 2 ‐based blood‐oxygen‐level‐dependent approach probing regional longitudinal fluctuations function porcine model AMI at 3 T. Ten...
Pulsed Field Ablation (PFA) is a new ablation method being rapidly adopted for treatment of atrial fibrillation, which shows advantages in safety and efficiency over radiofrequency cryo-ablation. In this study, we used an vivo swine model (10 healthy 5 with chronic myocardial infarct) ventricular PFA, collecting intracardiac electrograms, electro-anatomical maps, native T1-weighted late gadolinium enhancement MRI, gross pathology, histology. We 1000-1500 V pulses, 1-16 pulse trains to vary...
Catheter ablation of ventricular tachycardia (VT) is preceded by characterization the myocardial substrate via electroanatomical voltage mapping (EAVM). The purpose this study was to characterize relationship between chronic fibrotic scar detected multicontrast late enhancement (MCLE) MRI and EAVM obtained using an MR-guided electrophysiology system, with a final aim better understand how these measures may improve identification potentially arrhythmogenic substrates. Real-time performed in...
Previous studies have demonstrated that using hyperpolarized [2‐ 13 C]pyruvate as a contrast agent can reveal C signals from metabolites associated with the tricarboxylic acid (TCA) cycle. However, detectable TCA cycle‐mediated oxidation of are result several metabolic steps. In instance [5‐ C]glutamate signal, amplitude be modulated by changes to rates pyruvate dehydrogenase (PDH) flux, cycle flux and metabolite pool size. Also key is malate–aspartate shuttle, which facilitates transport...
Radiofrequency (RF) energy delivered to cardiac tissue produces a core ablation lesion with surrounding edema, the latter of which has been implicated in acute procedural failure Ventricular Tachycardia (VT) and late arrhythmia recurrence. This study sought investigate electrophysiological characteristics RF lesions left ventricle (LV) visualized native-contrast Magnetic Resonance Imaging (MRI).An MR-guided electrophysiology system was used deliver LV 8 swine (9 total), then perform MRI...
Most MR-guided catheter-based procedures, and imaging of patients with implanted medical devices, are currently contraindicated due to a significant risk heating associated induced RF currents. The current produces corresponding artifact which can be used remotely characterize safely predict heating. Application this remote technique in vivo quantify may allow for execution many scans contraindicated. Sources phase other than present difficulty practical vivo.A custom ultra-short echo time...
Following acute myocardial infarction (AMI), microvascular integrity and function may be compromised as a result of obstruction (MVO) vasodilator dysfunction. It has been observed that both infarcted remote territories exhibit impaired blood flow (MBF) patterns associated with an abnormal response. Arterial spin labeled (ASL) CMR is novel non-contrast technique can quantitatively measure MBF. This study investigates the feasibility ASL-CMR to assess MVO response in swine. Thirty-one swine...
Background Recently, there is an increased interest in using MRI to guide electrophysiology (EP) procedures as alternative X-ray fluoroscopy guidance, due its excellent soft tissue contrast and lack of radiation. However, exist tradeoffs between different guidance schemes. Realtime 2D MR sequences are able capture heart motion during interventional setting, while sacrificing imaging quality, whereas high-resolution prior 3D roadmaps static do not reflect the respiratory heart. In this work,...
Hemorrhage is recognized as a new independent predictor of adverse outcomes following acute myocardial infarction. However, the mechanisms its effects are less understood. The aim our study was to probe downstream impact hemorrhage towards chronic remodeling, including inflammation, vasodilator function and matrix alterations in an experimental model hemorrhage. Myocardial induced porcine heart by intracoronary injection collagenase. Animals ( N = 18) were subjected coronary occlusion...
In acute myocardial infarction (AMI), the aim of any therapeutic intervention is to reduce infarct size and attenuate adverse remodeling. The type extent encountered clinically [transmural, hemorrhagic, heterogeneous, with microvascular obstruction (MVO)], primarily determined by severity initial ischemic insult. Understanding in-vivo pathophysiological mechanisms after AMI as a function will be key in predicting functional recovery, prognosis assessing efficacy novel therapies.
Background Hemorrhage is a frequent complication in acute myocardial infarction (AMI) and speculated to be an independent predictor of adverse outcomes [1]. In addition infarct zone remodeling, the distal remote myocardium may experience alterations vasodilator dysfunction, edema, extracellular matrix (ECM) expansion [2-4]. The aim our study was understand impact hemorrhage on as well remodeling following ischemic event. To this end, we employed quantitative T1 T2 mapping probe underlying...