22 results on '"Katherine M. Kavanagh"'
Search Results
2. A Novel High-Resolution Surface Electrocardiographic Method to Identify and Characterize Myocardial Scar: A Proof-of-Concept Study
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Joel Xue, Andrew Roberts, James A. White, Karen Cowan, Derek S. Chew, Glen L. Sumner, Carmen P Lydell, Andrew G Howarth, Katherine M. Kavanagh, Derek V. Exner, Sharita Manga, and Gordon I. Rowlandson
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medicine.medical_specialty ,business.industry ,medicine.medical_treatment ,Cardiac resynchronization therapy ,High resolution ,Maximal amplitude ,Surface ecg ,Interquartile range ,RC666-701 ,Internal medicine ,Skin surface ,medicine ,Cardiology ,Diseases of the circulatory (Cardiovascular) system ,Original Article ,Cardiology and Cardiovascular Medicine ,Lead (electronics) ,business ,Cardiac magnetic resonance - Abstract
Résumé: Contexte: La mise en place de la sonde ventriculaire gauche dans une zone exempte de cicatrice myocardique est un facteur déterminant de la réponse au traitement de resynchronisation cardiaque. Nous avons cherché à développer et à valider une approche électrocardiographique (ECG) simple, concrète et novatrice afin de repérer de manière peropératoire la présence de tissu cicatriciel au ventricule gauche (VG). Nous avons émis l'hypothèse qu'il y aurait une diminution de l'amplitude du rythme de stimulation du ventricule gauche mesurée à la surface de la peau à l'ECG haute résolution (HR) lors de la stimulation de régions du VG présentant du tissu cicatriciel comparativement aux régions exemptes de cicatrices. Il s'agit de ce que nous appelons la méthode EASE (ECG Amplitude Signal Evaluation). Méthodologie: Des patients vus de manière consécutive qui présentaient une dysfonction systolique ischémique du VG et répondaient aux critères standard pour l'implantation de novo d'un dispositif de resynchronisation cardiaque ont été recrutés de manière prospective. Tous ont fait l'objet d'une résonance magnétique cardiaque améliorée par injection d'un produit de contraste avant l'implantation pour évaluer la présence de tissu cicatriciel. L'amplitude moyenne de l'impulsion de stimulation du VG a été échantillonnée sur l'ECG de surface HR réalisé pendant l'intervention, puis comparée aux résultats de la résonance magnétique cardiaque. Résultats: En tout, 38 points de stimulation du VG ont été évalués chez 13 receveurs. Le voltage médian mesuré sur l'ECG de surface HR dans les régions présentant du tissu cicatriciel était réduit de 41 % (intervalle interquartile : 17 % à 63 %), tandis qu'il n'y avait pas de changement mesurable du voltage (intervalle interquartile : 0 à 0 %) dans les régions exemptes de cicatrices par rapport à l'amplitude maximale (test de Wilcoxon, p < 0,0001). Conclusion: La méthode EASE semble avoir une utilité potentielle en tant que nouvel outil peropératoire pour guider la mise en place de la sonde ventriculaire gauche dans les régions exemptes de cicatrices. Il faudra réaliser d'autres travaux pour valider l'utilité de cette méthode dans une cohorte de patients plus importante. Abstract: Background: The placement of the left ventricular (LV) lead in an area free of myocardial scar is an important determinant of cardiac resynchronization therapy response. We sought to develop and validate a simple, practical, and novel electrocardiographic (ECG)-based approach to intraoperatively identify the presence of LV scar. We hypothesized that there would be a reduction in the measured amplitude of the LV pacing stimulus on the skin surface using a high-resolution (HR) ECG when pacing from LV regions with scar compared with regions without scar. We term this the ECG Amplitude Signal Evaluation (EASE) method. Methods: Consecutive patients with ischemic LV systolic dysfunction and standard criteria for de novo cardiac resynchronization therapy implantation were prospectively enrolled. All underwent a preimplant contrast-enhanced cardiac magnetic resonance study to assess for scar. The average amplitude of the LV pacing impulse was sampled on HR surface ECG intraprocedurally and then compared with the cardiac magnetic resonance results. Results: A total of 38 LV pacing sites were assessed among 13 recipients. The median voltage measured on the surface HR ECG in regions with scar was reduced by 41% (interquartile range, 17% to 63%), whereas there was no measurable change in voltage (interquartile range, 0 to 0%) in regions without scar compared with the maximal amplitude (Wilcoxon P < 0.0001). Conclusion: The EASE method appears to be of potential value as a novel intraoperative tool to guide LV lead placement to regions free of scar. Future work is required to validate the utility of this method in a larger patient cohort.
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- 2021
3. Left ventricular ejection fraction reassessment post–myocardial infarction: Current clinical practice and determinants of adverse remodeling
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Derek S. Chew, Derek V. Exner, Liong Eng Tan-Mesiatowsky, Danielle A. Southern, Katherine M. Kavanagh, Stephen B. Wilton, and Approach Investigators
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Male ,medicine.medical_specialty ,Databases, Factual ,Myocardial Infarction ,030204 cardiovascular system & hematology ,Risk Assessment ,Alberta ,Cohort Studies ,Ventricular Dysfunction, Left ,03 medical and health sciences ,0302 clinical medicine ,Predictive Value of Tests ,Internal medicine ,medicine ,Humans ,Registries ,cardiovascular diseases ,030212 general & internal medicine ,Myocardial infarction ,Survival rate ,Aged ,Retrospective Studies ,Ejection fraction ,Ventricular Remodeling ,biology ,business.industry ,Hazard ratio ,Age Factors ,Stroke Volume ,Retrospective cohort study ,Recovery of Function ,Middle Aged ,Prognosis ,medicine.disease ,Troponin ,Echocardiography, Doppler ,Survival Rate ,Logistic Models ,Multivariate Analysis ,Cohort ,cardiovascular system ,biology.protein ,Cardiology ,Female ,Myocardial infarction diagnosis ,Cardiology and Cardiovascular Medicine ,business - Abstract
Left ventricular (LV) dysfunction may be sustained or aggravated during the convalescent months following an acute myocardial infarction (MI) and is difficult to predict. We sought to determine current practice patterns of LV ejection fraction (LVEF) reassessment during the months following MI and evaluate the predictors and clinical significance of LVEF change in a prospective post-MI patient cohort.Patients with an acute MI between June 2010 and August 2014 were identified using the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease registry. Patients with initial LV dysfunction (LVEF40% with first MI or45% with multiple MI events) underwent a protocol-driven repeat LVEF assessment in follow-up if routine LVEF reassessment was not performed.Of 5,964 MI patients, follow-up LVEF assessments were attained for 442 of the 695 patients who had significant LV dysfunction. A sizable proportion (25%) had either no increase or a decline in LVEF. Adverse remodeling was associated with an anterior MI location, a greater peak serum troponin T, and a higher baseline LVEF at time of MI. Adverse LV remodeling conferred a 3-fold risk of death (hazard ratio 3.0, 95% CI 1.6-5.7, P=.001) adjusted for baseline LVEF, anterior MI location, and medication use.Current practice of LVEF reassessment during the convalescent months post-MI is suboptimal despite a sizeable proportion of patients that undergo adverse LV remodeling. Targeting processes affecting low rates of LVEF reassessment may reduce missed care opportunities and ensure that patients consistently receive appropriate evidence-based and guideline-recommended care.
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- 2018
4. Charting a Course for Cardiac Electrophysiology Training in Canada: The Vital Role of Fellows in Advanced Cardiovascular Care
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Carlos A. Morillo, Robert M. Gow, Lorne J. Gula, Richard Leather, Robert M. Hamilton, Adrian Baranchuk, Tomasz Hruczkowski, Gilles O'Hara, Louise Harris, Peter G. Guerra, Kamran Ahmad, Shubhayan Sanatani, M. Sturmer, Felix Ayala-Paredes, Paul Novak, Chris Gray, Martin S. Green, Ilan Lahevsky, Martin J. Gardner, Vidal Essebag, Andrew D. Krahn, Katherine M. Kavanagh, Shanta Chakrabarti, and Laurent Macle
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Canada ,Government ,Medical education ,Attitude of Health Personnel ,Status quo ,business.industry ,media_common.quotation_subject ,MEDLINE ,Flexibility (personality) ,Training (civil) ,Procurement ,Education, Medical, Graduate ,Excellence ,Surveys and Questionnaires ,Humans ,Medicine ,Cardiac Electrophysiology ,Fellowships and Scholarships ,Foreign Medical Graduates ,Cardiology and Cardiovascular Medicine ,business ,Function (engineering) ,media_common - Abstract
Canadian electrophysiology (EP) fellowship programs have evolved in an ad hoc fashion over 30 years. This evolution has occurred in many fields in medicine and is natural when innovators and pioneers attract research fellows who help change the status quo from predominantly research to a predominantly clinical application and focus. Fellows not only push their supervisors and their centres into new areas of inquiry but also function at the most advanced level to encourage and teach junior trainees and to provide examples of excellence to residents, medical students, and other health professionals. Funding for fellows has never been provided in the traditional way through the Ministry of Health or the Ministry of Advanced Education. Each Canadian centre has over the years found novel ways to fund fellowship programs, and many centres have used value-adds from procurement programs. These sources of funding are eroding as provincial government agencies are beginning to assume procurement responsibilities and local flexibility to fund fellowships is lost. In particular, provincial government agencies feel that valuable financial resources should be restricted to Canadian trainees only, despite the international consensus that fellowship is an essential time for advanced trainees to travel abroad to acquire a broad a range of experience, learn new techniques and approaches, make lifelong research connections, and hopefully return home with these skills and expertise. This article summarizes the long history of EP fellowship training in Canada, as well as EP fellowship experiences at home and abroad by Canadian electrophysiologists, in an attempt to contextualize these new realities.
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- 2013
5. Association of Rate-Controlled Persistent Atrial Fibrillation With Clinical Outcome and Ventricular Remodelling in Recipients of Cardiac Resynchronization Therapy
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Karen Cowan, François Philippon, Stephen B. Wilton, Derek V. Exner, Raymond Yee, Katherine M. Kavanagh, and Sandeep Aggarwal
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Male ,medicine.medical_specialty ,medicine.medical_treatment ,Cardiac resynchronization therapy ,Pilot Projects ,Cardiac Resynchronization Therapy ,Electrocardiography ,Heart Rate ,Internal medicine ,Atrial Fibrillation ,Clinical endpoint ,medicine ,Humans ,Sinus rhythm ,Prospective Studies ,Ventricular remodeling ,Aged ,Ventricular Remodeling ,medicine.diagnostic_test ,business.industry ,Stroke Volume ,Atrial fibrillation ,Stroke volume ,medicine.disease ,Echocardiography, Doppler ,Transplantation ,Treatment Outcome ,Cardiology ,Female ,Cardiology and Cardiovascular Medicine ,business ,Follow-Up Studies - Abstract
Background Whether patients with persistent atrial fibrillation (AF) obtain the same degree of benefit with cardiac resynchronization therapy (CRT) as those in sinus rhythm remains unclear. Methods We enrolled 93 patients undergoing CRT implantation, 20 (22%) of whom had rate-controlled persistent AF. The primary endpoint was CRT response defined as 1 class improvement in Specific Activity Scale and 15% reduction in left ventricular end-systolic volume (LVESV) during 12 months. Other endpoints included changes in 6-minute walk distance, quality of life, B-type natriuretic peptide, and survival. Results Baseline characteristics were similar in those with and without AF. Response to CRT was observed in 42% vs 54% of those with and without AF, respectively (P = 0.3). Both groups had significant improvements in 6-minute walk distance, quality of life, and LVESV, but the improvement in LVESV was smaller in those with AF (13.7% ± 14.9% vs 27.7% ± 23.7%; P = 0.02). During 2.8 ± 1.4 years of follow-up, AF was associated with a 2.2-fold increased risk of death or transplantation (95% confidence interval, 1.2-3.9; P = 0.01). Conclusions Compared with patients without rate-controlled persistent AF, those with rate-controlled persistent AF had similar rates of clinical improvement but less left ventricular reverse remodelling in the first year after CRT. AF was associated with a markedly higher risk of death or transplantation in long-term follow-up. Given these findings, randomized studies assessing CRT efficacy in those with AF are warranted.
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- 2011
6. Attenuated recovery of heart rate turbulence early after myocardial infarction identifies patients at high risk for fatal or near-fatal arrhythmic events
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Poul-Erik Bloch Thomsen, Katherine M. Kavanagh, Marc Messier, Heikki V. Huikuri, Derek V. Exner, Robert S. Sheldon, Daniel Becker, Sandeep Aggarwal, and L. Brent Mitchell
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Male ,medicine.medical_specialty ,Myocardial Infarction ,Infarction ,Risk Assessment ,Sudden death ,Heart rate turbulence ,Coronary artery disease ,Heart Conduction System ,Heart Rate ,Predictive Value of Tests ,Risk Factors ,Physiology (medical) ,Internal medicine ,medicine ,Humans ,Heart rate variability ,Myocardial infarction ,Clinical Trials as Topic ,Ejection fraction ,business.industry ,Arrhythmias, Cardiac ,Recovery of Function ,Baroreflex ,Middle Aged ,medicine.disease ,Death, Sudden, Cardiac ,Ventricular fibrillation ,Electrocardiography, Ambulatory ,Cardiology ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
Autonomic dysfunction tends to improve over time after acute myocardial infarction (MI), but the clinical significance of autonomic remodeling is not well known.The purpose of this study was to test the hypothesis that the amount of recovery of autonomic function early after MI is associated with a risk for serious arrhythmias.The prognostic significance of autonomic remodeling after MI was assessed in one post-MI cohort [Cardiac Arrhythmia and Risk Stratification after Myocardial Infarction (CARISMA)] and validated in a second cohort [Risk Estimation After Infarction, Noninvasive Evaluation (REFINE)]. Changes in heart rate variability (DeltaHRV) and heart rate turbulence (DeltaHRT) were measured from 24-hour ECG recordings performed early (5-21 days) and later (6 weeks) after MI in CARISMA (n = 312). DeltaHRV and DeltaHRT were similarly measured from early (2-4 weeks) and later (10-14 weeks) post-MI recordings in REFINE (n = 322).HRV and HRT increased over time in both cohorts. Attenuated recovery of autonomic function, defined as DeltaHRT slope2.0 ms/RR, was associated with a 9.4-fold (95% confidence interval 1.2-71.6; P = .03) higher risk of ECG-documented sustained ventricular tachycardia or ventricular fibrillation in CARISMA and a 7.0-fold (95% confidence interval 1.6-29.6; P = .009) higher risk of fatal or near-fatal events in REFINE. Changes in HRV and HRT were not predictive of nonarrhythmic death in either cohort.Attenuated recovery of autonomic function early after MI consistently predicts a higher risk of fatal or near-fatal arrhythmic events. A lack of improvement in HRT early after MI appears to be a specific marker for serious arrhythmic events.
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- 2010
7. CAN AMBULATORY ELECTROCARDIOGRAPHIC (HOLTER) TESTING ACCURATELY DIFFERENTIATE PATIENTS AT HIGHER VERSUS LOWER RISK OF DEATH AFTER MYOCARDIAL INFRACTION?
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Tomasz Hruczkowski, Derek V. Exner, Marie-Claude Guertin, Katherine M. Kavanagh, Raymond Yee, F. Philippon, H. Huikuri, Bernard Thibault, Ahmad Hersi, and Anthony Tang
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medicine.medical_specialty ,business.industry ,Ambulatory ,medicine ,Cardiology and Cardiovascular Medicine ,Intensive care medicine ,Lower risk ,business - Published
- 2017
8. Post-Exercise Assessment of Cardiac Repolarization Alternans in Patients With Coronary Artery Disease Using the Modified Moving Average Method
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Fincavas Investigators, Linda Ellis, Kjell Nikus, Jari Viik, Derek V. Exner, Michael P. Slawnych, Rami Lehtinen, Mika Kähönen, Refine, Katherine M. Kavanagh, Sandeep Aggarwal, Terho Lehtimäki, Darlene Ramadan, and Tuomo Nieminen
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Male ,medicine.medical_specialty ,Stress testing ,Coronary Disease ,risk stratification ,030204 cardiovascular system & hematology ,Lower risk ,Risk Assessment ,Coronary artery disease ,Electrocardiography ,03 medical and health sciences ,0302 clinical medicine ,Predictive Value of Tests ,Internal medicine ,medicine ,Humans ,030212 general & internal medicine ,Myocardial infarction ,Exercise ,Aged ,repolarization ,Ejection fraction ,medicine.diagnostic_test ,business.industry ,Middle Aged ,stress testing ,Prognosis ,medicine.disease ,3. Good health ,myocardial infarction ,Predictive value of tests ,Exercise Test ,Cardiology ,Female ,ambulatory ECG ,Cardiology and Cardiovascular Medicine ,Risk assessment ,business - Abstract
Objectives We sought to evaluate the utility of T-wave alternans (TWA) assessment in the immediate post-exercise period to identify and validate cutpoints for the modified moving average (MMA) assessment method. Background The presence of TWA is associated with an increased risk of cardiovascular death (CVD). The immediate post-exercise period, where increased physiologic stress and minimal surface artifact coexist, appears ideal to implement the MMA method. Methods A test (n = 322) and validation cohort (n = 681) provided 1,003 patients with coronary artery disease (CAD). We assessed TWA immediately after exercise. The outcomes, CVD and mortality, were adjudicated independent of the TWA results. Results During 48 months of follow-up 85 deaths, 54 categorized as CVD (64%), were observed. A linear relationship between the magnitude of TWA and the risk of CVD was identified. As a continuous measure TWA voltage was equivalent to ejection fraction in predicting the risk of CVD. To facilitate clinical application, a sensitive, modest predictive accuracy (20 μV) and a specific, greater predictive accuracy MMA cutpoint (60 μV) were identified and validated. Each cutpoint was associated with a 2.5-fold greater risk of CVD, independent of other important variables, including ejection fraction. Conclusions Post-exercise assessment of TWA using the MMA method is a strong, independent predictor of risk in patients with CAD. The 20-μV cutpoint (87% sensitivity) appears to be most suitable in higher-risk patients, whereas the 60-μV cutpoint (95% specificity) appears more appropriate when TWA is used as a single screening test in those at lower risk. (Assessment of Noninvasive Methods to Identify Patients at Risk of Serious Arrhythmias After a Heart Attack; NCT00399503 )
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- 2009
9. Noninvasive Risk Assessment Early After a Myocardial Infarction
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Catherine Noullett, James McMeekin, Refine Investigators, Michael P. Slawnych, Allie Van Schaik, Gregory Schnell, Gordon H. Fick, Henry J. Duff, L. Brent Mitchell, Mariko A. Shibata, Sajad Gulamhussein, Darlene Ramadan, Katherine M. Kavanagh, Derek V. Exner, Ryan T. Mitchell, Anne M. Gillis, Wayne Tymchak, Robert S. Sheldon, and Sandeep Aggarwal
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medicine.medical_specialty ,Ejection fraction ,business.industry ,Autonomic tone ,030204 cardiovascular system & hematology ,medicine.disease ,Heart rate turbulence ,03 medical and health sciences ,0302 clinical medicine ,Multicenter study ,Predictive value of tests ,Internal medicine ,medicine ,Cardiology ,Myocardial infarction complications ,030212 general & internal medicine ,Myocardial infarction ,Cardiology and Cardiovascular Medicine ,Risk assessment ,business - Abstract
Objectives This study sought to determine whether combined assessment of autonomic tone plus cardiac electrical substrate identifies most patients at risk of serious events after myocardial infarction (MI) and to compare assessment at 2 to 4 weeks versus 10 to 14 weeks after MI. Background Methods to identify most patients at risk of serious events after MI are required. Methods Patients (n = 322) with an ejection fraction (EF) Results Mean EF significantly increased over the initial 8 weeks after MI. Testing 2 to 4 weeks after MI did not reliably identify patients at risk, whereas testing at 10 to 14 weeks did. The 20% of patients with impaired HRT, abnormal exercise TWA, and an EF Conclusions Impaired HRT, abnormal TWA, and an EF http://www.clinicaltrials.gov/ct/show/NCT00399503?order=1 ; NCT00399503 )
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- 2007
10. FACTORS ASSOCIATED WITH LEFT VENTRICULAR REMODELING POST-MYOCARDIAL INFARCTION
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Caroline Mesiatowsky, Rosza Sas, Margaret Morck, Derek V. Exner, Derek S. Chew, and Katherine M. Kavanagh
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medicine.medical_specialty ,business.industry ,Internal medicine ,Cardiology ,Medicine ,Electrocardiography in myocardial infarction ,business ,Ventricular remodeling ,medicine.disease ,Cardiology and Cardiovascular Medicine ,Post myocardial infarction - Published
- 2015
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11. Pulmonary edema postcardioversion: A potential calcium signalling problem
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Ahmad Hersi, Jonathan B. Choy, Paul W. Armstrong, Katherine M. Kavanagh, and Sajad Gulamhusein
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Tachycardia ,medicine.medical_specialty ,Adenosine ,medicine.medical_treatment ,Electric Countershock ,Pulmonary Edema ,Case Report ,Cardioversion ,Electrocardiography ,Internal medicine ,Tachycardia, Supraventricular ,medicine ,Humans ,Tachycardia, Atrioventricular Nodal Reentry ,Calcium Signaling ,cardiovascular diseases ,medicine.diagnostic_test ,business.industry ,Middle Aged ,Pulmonary edema ,medicine.disease ,Treatment Outcome ,Verapamil ,Anesthesia ,cardiovascular system ,Cardiology ,Drug Therapy, Combination ,Female ,Supraventricular tachycardia ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,Anti-Arrhythmia Agents ,Echocardiography, Transesophageal ,medicine.drug - Abstract
The present report describes an unusual case of pulmonary edema after adenosine cardioversion of a supraventricular tachycardia. Despite a structurally normal heart, a 52-year-old woman presented with pulmonary edema on two separate occasions, having had her atrioventricular nodal re-entrant tachycardia terminated with 12 mg of intravenous adenosine. A third similar episode of tachycardia that was terminated with verapamil was not complicated by pulmonary edema.
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- 2006
12. Cardiac video analysis using Hodge–Helmholtz field decomposition
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Gang Liu, Qinghong Guo, Katherine M. Kavanagh, and Mrinal Mandal
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Field (physics) ,Anisotropic diffusion ,Quantitative Biology::Tissues and Organs ,Physics::Medical Physics ,Models, Cardiovascular ,Video Recording ,Health Informatics ,Geometry ,Computer Science Applications ,Maxima and minima ,symbols.namesake ,Motion field ,Heart Conduction System ,Motion estimation ,Helmholtz free energy ,Ventricular Fibrillation ,Image Processing, Computer-Assisted ,Linear Models ,symbols ,Humans ,Vector field ,Algorithm ,Algorithms ,Smoothing ,Mathematics - Abstract
The critical points (also known as phase singularities) in the heart reflect the pathological change of the heart tissue, and hence can be used to describe and analyze the dynamics of the cardiac electrical activity. As a result, the detection of these critical points can lead to correct understanding and effective therapy of the tachycardia. In this paper, we propose a novel approach to address this problem. The proposed approach includes four stages: image smoothing, motion estimation, motion decomposition, and detection of the critical points. In the image smoothing stage, the noisy cardiac optical data are smoothed using anisotropic diffusion equation. The conduction velocity fields of the cardiac electrical patterns can then be estimated from two consecutive smoothed images. Using the recently developed discrete Hodge-Helmholtz motion decomposition technique, the curl-free and divergence-free potential surfaces of an estimated velocity field are extracted. Finally, hierarchically searching the minima and maxima on the potential surfaces, the sources, sinks, and rotational centers are located with high accuracy. Experimental results with four real cardiac videos show that the proposed approach performs satisfactorily, especially for the cardiac electrical patterns with simple propagations.
- Published
- 2006
13. THE PRESENCE OF FRAGMENTED QRS COMPLEXES EARLY AFTER ACUTE MYOCARDIAL INFARCTION IS ASSOCIATED WITH SUBSEQUENT LACK OF FAVORABLE LEFT VENTRICULAR REMODELING
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Derek V. Exner, Danielle A. Southern, Rozsa Sas, Caroline Liong Eng Tan-Mesiatowsky, Andrew G Howarth, James A. White, Derek S. Chew, Haris Vaid, Stephen B. Wilton, and Katherine M. Kavanagh
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medicine.medical_specialty ,Ejection fraction ,business.industry ,Fragmented qrs ,medicine.disease ,Internal medicine ,cardiovascular system ,medicine ,Cardiology ,cardiovascular diseases ,Myocardial infarction ,Cardiology and Cardiovascular Medicine ,business ,Ventricular remodeling ,circulatory and respiratory physiology - Abstract
Background: Recovery of left ventricular ejection fraction (LVEF) after myocardial infarction (MI) is not universal and is difficult to predict. Fragmented QRS (fQRS) complexes are thought to be a marker of myocardial scar, and are defined as various RSR’ patterns on a 12-lead surface
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- 2017
14. Characteristics of patients with nonfatal cardiac arrest 3 to 180 days after acute myocardial infarction
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L. Brent Mitchell, Katherine M. Kavanagh, Henry J. Duff, D. George Wyse, Anne M. Gillis, and Robert S. Sheldon
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Adult ,Male ,Tachycardia ,medicine.medical_specialty ,Myocardial Infarction ,Ventricular tachycardia ,Electrocardiography ,Actuarial Analysis ,Recurrence ,Internal medicine ,medicine ,Humans ,cardiovascular diseases ,Myocardial infarction ,Survival analysis ,Aged ,Retrospective Studies ,Aged, 80 and over ,Ejection fraction ,medicine.diagnostic_test ,business.industry ,Cardiac Pacing, Artificial ,Stroke Volume ,Stroke volume ,Middle Aged ,medicine.disease ,Survival Analysis ,Heart Arrest ,Tachycardia, Ventricular ,cardiovascular system ,Cardiology ,Myocardial infarction complications ,Female ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,Follow-Up Studies - Abstract
Patients who survive a tachyarrhythmic cardiac arrest in the first 6 months after acute myocardial infarction (AMI) are at risk for recurrent arrests, but the magnitude, timing and characteristics of this phenomenon are unknown. This study characterizes the nature of recurrent tachyarrhythmic cardiac arrests in the absence of reversible factors or new myocardial necrosis in patients between 3 and 180 days after AMI. We retrospectively assessed 28 patients (mean age 61 +/- 12 years) who survived an initial cardiac arrest a median of 10 days after AMI. Mean left ventricular ejection fraction was 36 +/- 9%. Fourteen patients (50%) had at least 1 recurrence of cardiac arrest, and 10 had > 2 arrests. Almost all (92%) recurrent cardiac arrests occurred within 5 days of the preceding arrest, and the high-risk periods were similar after the first, second or third cardiac arrest. Very fast ventricular tachycardia (mean cycle length 212 +/- 30 ms) was the documented responsible arrhythmia in 44 of 51 cardiac arrests. The morphology was either polymorphic, monomorphic or sinusoidal. No clinical or laboratory values could be found that predicted whether a patient would have a recurrent arrest. Nineteen patients (68%) survived to leave the hospital and have been followed for up to 96 months. For these, actuarial 5-year overall survival was 76% and actuarial 5-year arrhythmia-free probability was 80%. Thus, patients who survive a cardiac arrest in the first 6 months after AMI are at high risk of recurrent cardiac arrest for a further 5 days, and the arrests are due to characteristically fast ventricular tachycardias.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1993
15. Drug therapy for ventricular tachyarrhythmias: How many electropharmacologic trials are appropriate?
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L. Brent Mitchell, Henry J. Duff, Anne M. Gillis, Robert S. Sheldon, D. George Wyse, and Katherine M. Kavanagh
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Male ,medicine.medical_specialty ,Drug trial ,Time Factors ,business.industry ,Ventricular Tachyarrhythmias ,Cardiac Pacing, Artificial ,Middle Aged ,Surgery ,PAROXYSMAL VENTRICULAR TACHYCARDIA ,Clinical trial ,Electrophysiology ,Pharmacotherapy ,Actuarial Analysis ,Internal medicine ,Tachycardia ,Ventricular Fibrillation ,Cardiology ,Medicine ,Humans ,Female ,business ,Cardiology and Cardiovascular Medicine ,Anti-Arrhythmia Agents ,Probability - Abstract
To determine how many electropharmacologic drug trials should be performed to select therapy for patients with ventricular tachyarrhythmias, the outcome of 150 consecutive patients with inducible ventricular tachyarrhythmias undergoing serial electropharmacologic testing was examined. The probability of identifying predicted effective therapy (inductive of fewer than five ventricular responses with three ventricular extrastimuli at three pacing cycle lengths) and the probability of that therapy preventing sustained ventricular tachyarrhythmia recurrences were determined as a function of the number of preceding trials. The probability ( +/- SE) of identifying predicted effective therapy by the first trial (0.23 +/- 0.03) was significantly higher than that of the second (0.09 +/- 0.04), third (0.08 +/- 0.04) and fourth (0.05 +/- 0.04) trials (p = 0.001). No patient had predicted effective therapy identified by subsequent trials. The 2 year actuarial probability of freedom from sustained ventricular tachyarrhythmias on predicted effective therapy was higher for the first (0.79 +/- 0.08), second (0.73 +/- 0.13) and third (0.86 +/- 0.13) trials than for the fourth (0.33 +/- 0.27) trial (p = 0.02). Thus, the probability of selecting therapy with long-term efficacy was highest for the first trial (0.18), intermediate for the second (0.07) and third (0.07) trials and lowest for the fourth (0.02) and subsequent (0.00) trials. Accordingly, the electropharmacologic approach to therapy selection should be abandoned after three unsuccessful trials.
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- 1991
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16. THE DEGREE OF LEFT VENTRICULAR EJECTION FRACTION CHANGE FOLLOWING MYOCARDIAL INFARCTION PREDICTS RISK OF SUDDEN CARDIAC ARREST
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Georg Schmidt, Heikki Huikuri, Derek V. Exner, Derek S. Chew, Michael Dommasch, Poul Erik Bloch Thomsen, Pekka Raatikainen, Daniel Sinnecker, and Katherine M. Kavanagh
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medicine.medical_specialty ,Ejection fraction ,Adverse outcomes ,business.industry ,Electrocardiography in myocardial infarction ,Sudden cardiac arrest ,medicine.disease ,Degree (temperature) ,Internal medicine ,cardiovascular system ,Cardiology ,medicine ,cardiovascular diseases ,Myocardial infarction ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business - Abstract
A depressed left ventricular (LV) ejection fraction (EF) early after myocardial infarction (MI) identifies patients at risk of adverse outcomes. Whether the change in LVEF in the weeks to months following MI provides additional information on prognosis is less certain. We hypothesized that a lack of
- Published
- 2015
17. A SIMPLE Method OF ESTIMATING BENEFIT PRIOR TO CARDIAC RESYNCHRONIZATION THERAPY
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Karen Cowan, Katherine M. Kavanagh, Derek V. Exner, G. Sumner, and S. Manga
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medicine.medical_specialty ,business.industry ,Internal medicine ,medicine.medical_treatment ,medicine ,Cardiac resynchronization therapy ,Cardiology ,Cardiology and Cardiovascular Medicine ,business ,Simple (philosophy) - Published
- 2014
18. Does biventricular pacing decrease the incidence of microvolt T-wave alternans?
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Alberta Van Schaik, Raymund C. Leung, Katherine M. Kavanagh, and Sajad Gulamhusein
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medicine.medical_specialty ,business.industry ,Incidence (epidemiology) ,Internal medicine ,Cardiology ,Medicine ,cardiovascular diseases ,T wave alternans ,business ,Cardiology and Cardiovascular Medicine - Published
- 2003
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19. Infrequent Reassessment of Left Ventricular Systolic Function Following Myocardial Infarction: A Reflection of Appropriate Care or Is There a Need for Guidelines in This Area?
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M. Morck, Rozsa Sas, Derek V. Exner, T. Oliviera, Katherine M. Kavanagh, and Derek S. Chew
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medicine.medical_specialty ,business.industry ,Internal medicine ,medicine ,Cardiology ,Reflection (physics) ,Electrocardiography in myocardial infarction ,Myocardial infarction ,Systolic function ,Cardiology and Cardiovascular Medicine ,medicine.disease ,business - Published
- 2013
20. Increased repolarization alternans following myocardial infarction is related to adverse left ventricular remodeling: Implications for risk assessment & use of defibrillator therapy
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Henry J. Duff, Katherine M. Kavanagh, Darlene Ramadan, Sandeep Aggarwal, Mariko Shibata, Ryan T. Mitchell, and Derek V. Exner
- Subjects
medicine.medical_specialty ,business.industry ,Electrocardiography in myocardial infarction ,medicine.disease ,Physiology (medical) ,Internal medicine ,medicine ,Cardiology ,Repolarization ,Myocardial infarction ,Cardiology and Cardiovascular Medicine ,Risk assessment ,business ,Ventricular remodeling - Published
- 2005
21. Substantial reduction in defibrillation thresholds in dogs using a one capacitor dual biphasic waveform and multielectrode nonthoracotomy lead configurations
- Author
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Patrick D. Wolf, Katherine M. Kavanagh, Clif A. Alferness, Jenny A. Hagler, Raymond E. Ideker, Sharon B. Melnick, Paul A. Guse, and Dennis L. Rollins
- Subjects
business.industry ,Defibrillation ,medicine.medical_treatment ,Biphasic waveform ,law.invention ,Dual (category theory) ,Reduction (complexity) ,Capacitor ,law ,Medicine ,Cardiology and Cardiovascular Medicine ,Lead (electronics) ,business ,Biomedical engineering - Published
- 1991
22. Epicardial mapping of ventricular tachycardia induced by a large premature stimulus over nontransmural infarcts
- Author
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J. Scott Kabas, Dennis L. Rollins, Katherine M. Kavanagh, William M. Smith, Sharon B. Melnick, and Raymond E. Ideker
- Subjects
medicine.medical_specialty ,Myocardial Infarction ,Stimulus (physiology) ,Ventricular tachycardia ,Dogs ,Tachycardia ,Internal medicine ,Animals ,Medicine ,cardiovascular diseases ,Cycle length ,Epicardial mapping ,business.industry ,Heart ,Reentry ,medicine.disease ,Electric Stimulation ,Induced ventricular tachycardia ,medicine.anatomical_structure ,Ventricle ,Ventricular Fibrillation ,Ventricular fibrillation ,cardiovascular system ,Cardiology ,Cardiology and Cardiovascular Medicine ,business - Abstract
Mapping has recently shown that electrically induced ventricular tachycardia (VI) and ventricular fibrillation (VF) both begin as figure-8 reentry: VI with a longer cycle length from spared tissue adjacent to an infarct (inf) and VF with a shorter cycle length from tissue around the electrode from which a large premature S2 is given. These results suggest the cycle length of the figure-8 rather than the mode of induction determines the type of arrhythmia. Thus a protocol similar to that by which a VF threshold is determined may induce VI rather than VFwhen performed in the spared tissue over an inf. We tested this hypothesis in 10 dogs in which the proximal LAD was partially occluded for 30 minutes. totally occluded for 90 minutes and then reperfused. Four days later a 3 x 3 cm plaque containing 121 recording electrodes was centered over the epicardial inf area. Ten S I stimuli were delivered from a total of 33 right ventricle and left ventricle sites outside the inf. An S2 was given to the epicardium over the
- Published
- 1991
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