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Rayani K, Davies B, Cheung M, Comber D, Roberts JD, Tadros R, Green MS, Healey JS, Simpson CS, Sanatani S, Steinberg C, MacIntyre C, Angaran P, Duff H, Hamilton R, Arbour L, Leather R, Seifer C, Fournier A, Atallah J, Kimber S, Makanjee B, Alqarawi W, Cadrin-Tourigny J, Joza J, Gardner M, Talajic M, Bagnall RD, Krahn AD, Laksman ZWM. Identification and in-silico characterization of splice-site variants from a large cardiogenetic national registry. Eur J Hum Genet 2023; 31:512-520. [PMID: 36138163 PMCID: PMC10172209 DOI: 10.1038/s41431-022-01193-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 08/23/2022] [Accepted: 09/08/2022] [Indexed: 11/08/2022] Open
Abstract
Splice-site variants in cardiac genes may predispose carriers to potentially lethal arrhythmias. To investigate, we screened 1315 probands and first-degree relatives enrolled in the Canadian Hearts in Rhythm Organization (HiRO) registry. 10% (134/1315) of patients in the HiRO registry carry variants within 10 base-pairs of the intron-exon boundary with 78% (104/134) otherwise genotype negative. These 134 probands were carriers of 57 unique variants. For each variant, American College of Medical Genetics and Genomics (ACMG) classification was revisited based on consensus between nine in silico tools. Due in part to the in silico algorithms, seven variants were reclassified from the original report, with the majority (6/7) downgraded. Our analyses predicted 53% (30/57) of variants to be likely/pathogenic. For the 57 variants, an average of 9 tools were able to score variants within splice sites, while 6.5 tools responded for variants outside these sites. With likely/pathogenic classification considered a positive outcome, the ACMG classification was used to calculate sensitivity/specificity of each tool. Among these, Combined Annotation Dependent Depletion (CADD) had good sensitivity (93%) and the highest response rate (131/134, 98%), dbscSNV was also sensitive (97%), and SpliceAI was the most specific (64%) tool. Splice variants remain an important consideration in gene elusive inherited arrhythmia syndromes. Screening for intronic variants, even when restricted to the ±10 positions as performed here may improve genetic testing yield. We compare 9 freely available in silico tools and provide recommendations regarding their predictive capabilities. Moreover, we highlight several novel cardiomyopathy-associated variants which merit further study.
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Affiliation(s)
- Kaveh Rayani
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Brianna Davies
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Matthew Cheung
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Drake Comber
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Jason D Roberts
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, ON, Canada
| | - Rafik Tadros
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Martin S Green
- Heart Institute, University of Ottawa, Ottawa, ON, Canada
| | | | | | | | - Christian Steinberg
- Institut Universitaire de Cardiologie et Pneumologie de Quebec, Laval University, Quebec City, QC, Canada
| | - Ciorsti MacIntyre
- Division of Cardiology, QEII Health Sciences Center, Halifax, NS, Canada
| | - Paul Angaran
- St Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Henry Duff
- Libin Cardiovascular Institute, University of Calgary, Calgary, AB, Canada
| | - Robert Hamilton
- Division of Cardiology, The Hospital for Sick Children (SickKids), Toronto, ON, Canada
| | - Laura Arbour
- Division of Medical Genetics, Island Health, Victoria, BC, Canada
| | | | - Colette Seifer
- Section of Cardiology, Department of Internal Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - Anne Fournier
- Division of Pediatric Cardiology, CHU Sainte-Justine, Universite de Montreal, Montreal, QC, Canada
| | - Joseph Atallah
- Division of Pediatric Cardiology, University of Alberta Stollery Children's Hospital, Edmonton, AB, Canada
| | - Shane Kimber
- Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Bhavanesh Makanjee
- Heart Health Institute, Scarborough Health Network, Scarborough, ON, Canada
| | - Wael Alqarawi
- Heart Institute, University of Ottawa, Ottawa, ON, Canada
| | - Julia Cadrin-Tourigny
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Jacqueline Joza
- Division of Cardiology, McGill University Health Centre, Montreal, QC, Canada
| | - Martin Gardner
- Division of Cardiology, QEII Health Sciences Center, Halifax, NS, Canada
| | - Mario Talajic
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Richard D Bagnall
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Andrew D Krahn
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Zachary W M Laksman
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
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Sobolewska V, Duff H, Craighead F, Macpherson I, Veiraiah A, Dummer S, Lockman KA. Improving care for patients in the outlying wards: Lessons from patients' care experience. Acute Med 2022; 21:80-85. [PMID: 35681181 DOI: 10.52964/amja.0902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
IMPORTANCE Overcrowding in hospitals and lack of capacity in general medical wards can result in a medical patient being transferred to other specialty wards often referred as 'outlying' or 'boarding' wards. OBJECTIVES We explored the experiences of our outlying patients to identify local factors that affect their care experience and inform interventions that could improve their care deliveries and outcomes. DESIGN, SETTING, AND PARTICIPANTS Qualitative interviews using semi-structured questions were conducted in 21 medical patients from a mixture of specialty wards in a large tertiary NHS hospital. MAIN OUTCOMES AND MEASURES Perceptions of the factors contributing to the experience of being a patient on a boarding ward, and potential solutions. RESULTS Almost all participants reported experiences of good care in an outlying ward. Positive comments highlighted good nursing care, restful environment and a strong focus on patient-centred care. However, none of the participants could identify the team or consultant responsible for their care and this was linked to multiple doctors being involved in the patient's care. Participants also perceived that the frequency of review was reduced and occurred much later in the day than that experienced in the medical ward. Most felt indifferent about the care ownership, timing and frequency of review but in some cases, this led to confusion and the perception of poor progress. Further, participants felt that they had to actively seek information relating to clinical progress. Negative experience of discharge planning was also reported. The associated themes included conflicting information and delays in social care provision. This led to anxiety, frustration and the perception of being a barrier to patient flow. CONCLUSIONS AND RELEVANCE Patient experience of the outlying ward is positive, and this can provide a foundation for improvement. Our findings suggest that better care processes and improved communication are needed to promote equity and quality of care. However, this should be complemented with efforts to overcome wider challenges that affect the entire continuum of flow within the healthcare system.
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Affiliation(s)
- V Sobolewska
- MBChB, NHS Lothian, Department of Acute and General Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, Scotland, United Kingdom
| | - H Duff
- MBChB, NHS Lothian, Department of Acute and General Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, Scotland, United Kingdom
| | - F Craighead
- MBChB, NHS Lothian, Department of Acute and General Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, Scotland, United Kingdom
| | - I Macpherson
- MBChB, Gut Group, University of Dundee, Dundee, UK. ORCID ID https://orcid.org/0000-0003-0443-2073, Department of Acute and General Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, Scotland, United Kingdom
| | - A Veiraiah
- MBBS, NHS Lothian, Department of Acute and General Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, Scotland, United Kingdom
| | - S Dummer
- MBChB, NHS Lothian, Department of Acute and General Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, Scotland, United Kingdom
| | - K A Lockman
- MB Bch MD FRCP, NHS Lothian, Department of Acute and General Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, Scotland, United Kingdom
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Comber DA, Davies B, Roberts JD, Tadros R, Green MS, Healey JS, Simpson CS, Sanatani S, Steinberg C, MacIntyre C, Angaran P, Duff H, Hamilton R, Arbour L, Leather R, Seifer C, Fournier A, Atallah J, Kimber S, Makanjee B, Alqarawi W, Cadrin-Tourigny J, Joza J, Gibbs K, Robb L, Zahavich L, Gardner M, Talajic M, Virani A, Krahn AD, Lehman A, Laksman ZWM. Return of Results Policies for Genomic Research: Current Practices & The Hearts in Rhythm Organization Approach. Can J Cardiol 2021; 38:526-535. [PMID: 34715283 DOI: 10.1016/j.cjca.2021.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 11/02/2022] Open
Abstract
Research teams developing biobanks and/or genomic databases must develop policies for the disclosure and reporting of potentially actionable genomic results to research participants. Currently, a broad range of approaches to the return of results exist, with some studies opting for non-disclosure of research results while others follow clinical guidelines for the return of potentially actionable findings from sequencing. In this review, we describe current practices and highlight decisions a research team must make when designing a return of results policy, from informed consent to disclosure practices and clinical validation options. The unique challenges of returning incidental findings in cardiac genes, including reduced penetrance and the lack of clinical screening standards for phenotype-negative individuals are discussed. Lastly, the National Hearts in Rhythm Organization (HiRO) Registry approach is described to provide a rationale for the selective return of field-specific variants to those participating in disease-specific research. Our goal is to provide researchers with a resource when developing a return of results policy tailored for their research program, based on unique factors related to study design, research team composition and availability of clinical resources.
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Affiliation(s)
- Drake A Comber
- Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Brianna Davies
- Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Jason D Roberts
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, ON, Canada
| | - Rafik Tadros
- Cardiovascular Genetics Center, Montreal Heart Institute, and Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Martin S Green
- University of Ottawa Heart Institute, Ottawa, ON, Canada
| | | | | | | | - Christian Steinberg
- Institut Universitaire de Cardiologie et Pneumologie de Québec, Laval University, Quebec City, QC, Canada
| | | | - Paul Angaran
- St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Henry Duff
- Libin Cardiovascular Institute, University of Calgary, Calgary, AB, Canada
| | - Robert Hamilton
- The Hospital for Sick Children (SickKids), Toronto, ON, Canada
| | - Laura Arbour
- Department of Medical Genetics, University of British Columbia and Island Health, Victoria, BC, Canada
| | | | - Colette Seifer
- Section of Cardiology, Department of Internal Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - Anne Fournier
- Division of Pediatric Cardiology, CHU Sainte-Justine, Université de Montréal, Montreal, QC, Canada
| | - Joseph Atallah
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Shane Kimber
- Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Bhavanesh Makanjee
- Heart Health Institute, Scarborough Health Network, Scarborough, ON, Canada
| | - Wael Alqarawi
- University of Ottawa Heart Institute, Ottawa, ON, Canada
| | - Julia Cadrin-Tourigny
- Cardiovascular Genetics Center, Montreal Heart Institute, and Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Jacqueline Joza
- Division of Cardiology, McGill University Health Centre, Montreal, QC, Canada
| | - Karen Gibbs
- Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Laura Robb
- Cardiovascular Genetics Center, Montreal Heart Institute, and Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Laura Zahavich
- The Hospital for Sick Children (SickKids), Toronto, ON, Canada
| | | | - Mario Talajic
- Cardiovascular Genetics Center, Montreal Heart Institute, and Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Alice Virani
- Department of Medical Genetics, The University of British, Columbia, Vancouver, British Columbia, Canada
| | - Andrew D Krahn
- Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Anna Lehman
- Department of Medical Genetics, The University of British, Columbia, Vancouver, British Columbia, Canada
| | - Zachary W M Laksman
- Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
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4
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Steinberg C, Davies B, Mellor G, Tadros R, Laksman ZW, Roberts JD, Green M, Alqarawi W, Angaran P, Healey J, Sanatani S, Leather R, Seifer C, Fournier A, Duff H, Gardner M, McIntyre C, Hamilton R, Simpson CS, Krahn AD. Short-coupled ventricular fibrillation represents a distinct phenotype among latent causes of unexplained cardiac arrest: a report from the CASPER registry. Eur Heart J 2021; 42:2827-2838. [PMID: 34010395 DOI: 10.1093/eurheartj/ehab275] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 02/14/2021] [Accepted: 04/27/2021] [Indexed: 12/25/2022] Open
Abstract
AIMS The term idiopathic ventricular fibrillation (IVF) describes survivors of unexplained cardiac arrest (UCA) without a specific diagnosis after clinical and genetic testing. Previous reports have described a subset of IVF individuals with ventricular arrhythmia initiated by short-coupled trigger premature ventricular contractions (PVCs) for which the term short-coupled ventricular fibrillation (SCVF) has been proposed. The aim of this article is to establish the phenotype and frequency of SCVF in a large cohort of UCA survivors. METHODS AND RESULTS We performed a multicentre study including consecutive UCA survivors from the CASPER registry. Short-coupled ventricular fibrillation was defined as otherwise unexplained ventricular fibrillation initiated by a trigger PVC with a coupling interval of <350 ms. Among 364 UCA survivors, 24/364 (6.6%) met diagnostic criteria for SCVF. The diagnosis of SCVF was obtained in 19/24 (79%) individuals by documented ventricular fibrillation during follow-up. Ventricular arrhythmia was initiated by a mean PVC coupling interval of 274 ± 32 ms. Electrical storm occurred in 21% of SCVF probands but not in any UCA proband (P < 0.001). The median time to recurrent ventricular arrhythmia in SCVF was 31 months. Recurrent ventricular fibrillation resulted in quinidine administration in 12/24 SCVF (50%) with excellent arrhythmia control. CONCLUSION Short-coupled ventricular fibrillation is a distinct primary arrhythmia syndrome accounting for at least 6.6% of UCA. As documentation of ventricular fibrillation onset is necessary for the diagnosis, most cases are diagnosed at the time of recurrent arrhythmia, thus the true prevalence of SCVF remains still unknown. Quinidine is effective in SCVF and should be considered as first-line treatment for patients with recurrent episodes.
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Affiliation(s)
- Christian Steinberg
- Cardiac Electrophysiology Service, Department of Cardiology and Cardiac Surgery, Institut universitaire de cardiologie et pneumologie de Québec, Laval University, 2725, Chemin Ste-Foy, Quebec, QC G1V 4G5, Canada
| | - Brianna Davies
- Heart Rhythm Services, Department of Medicine, St-Paul's Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Greg Mellor
- Cardiac Electrophysiology Service, Royal Papworth Hospital, Cambridge, UK
| | - Rafik Tadros
- Section of Cardiac Electrophysiology, Montreal Heart Institute, University of Montreal, Montreal, QC, Canada
| | - Zachary W Laksman
- Heart Rhythm Services, Department of Medicine, St-Paul's Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Jason D Roberts
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, ON, Canada
| | - Martin Green
- Cardiac Electrophysiology Service, Ottawa Heart Institute, University of Ottawa, Ottawa, ON, Canada
| | - Wael Alqarawi
- Cardiac Electrophysiology Service, Ottawa Heart Institute, University of Ottawa, Ottawa, ON, Canada
| | - Paul Angaran
- Cardiac Arrhythmia Service, St-Michael's Hospital, Toronto, ON, Canada
| | - Jeffrey Healey
- Arrhythmia Services Hamilton Health Sciences, Population Health Research Institute, McMaster University, Hamilton, ON, Canada
| | | | - Richard Leather
- Cardiac Electrophysiology Service, Royal Jubilee Hospital, Victoria, BC, Canada
| | - Colette Seifer
- St-Boniface Hospital, University of Manitoba, Winnipeg, MB, Canada
| | - Anne Fournier
- Division of Pediatric Cardiology, Department of Pediatrics, Centre Hospitalier Universitaire de Sainte-Justine, Montreal, QC, Canada
| | - Henry Duff
- Division of Cardiology, Libin Cardiovascular Institute, University of Calgary, Calgary, AB, Canada
| | - Martin Gardner
- Cardiac Electrophysiology Service, QEII Health Sciences Center, Dalhousie University, Halifax, NS, Canada
| | - Ciorsti McIntyre
- Cardiac Electrophysiology Service, QEII Health Sciences Center, Dalhousie University, Halifax, NS, Canada
| | - Robert Hamilton
- Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | | | - Andrew D Krahn
- Heart Rhythm Services, Department of Medicine, St-Paul's Hospital, University of British Columbia, Vancouver, BC, Canada
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5
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Cheung C, Laksman Z, Roberts J, Green M, Healey J, Sanatani S, Arbour L, Leather R, Chauhan V, Steinberg C, Angaran P, Duff H, Chakrabarti S, Simpson C, Talajic M, Tadros R, Seifer C, Gardner M, Krahn A. ARRHYTHMIC OUTCOMES IN CARDIAC ARREST SURVIVORS WITH PRESERVED EJECTION FRACTION REGISTRY (CASPER). Can J Cardiol 2018. [DOI: 10.1016/j.cjca.2018.07.296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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6
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Noskov S, Duff H, Perissinotti L, Guo J, Kudaibergenova M. Molecular Mechanisms of hERG Potassium Channel Interactions with Ivabradine: Importance of the Lipophilic Route. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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7
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Leung KC, Quinn RR, Ravani P, Duff H, MacRae JM. Randomized Crossover Trial of Blood Volume Monitoring-Guided Ultrafiltration Biofeedback to Reduce Intradialytic Hypotensive Episodes with Hemodialysis. Clin J Am Soc Nephrol 2017; 12:1831-1840. [PMID: 29018100 PMCID: PMC5672962 DOI: 10.2215/cjn.01030117] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 07/13/2017] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND OBJECTIVES Intradialytic hypotension (IDH) is associated with morbidity. The effect of blood volume-guided ultrafiltration biofeedback, which automatically adjusts fluid removal rate on the basis of blood volume parameters, on the reduction of IDH was tested in a randomized crossover trial. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We performed a 22-week, single blind, randomized crossover trial in patients receiving maintenance hemodialysis who had >30% of sessions complicated by symptomatic IDH in five centers in Calgary, Alberta, Canada. Participants underwent a 4-week run-in period to standardize dialysis prescription and dry weight on the basis of clinical examination. Those meeting inclusion criteria were randomized to best clinical practice hemodialysis (control) or best clinical practice plus blood volume-guided ultrafiltration biofeedback (intervention) for 8 weeks, followed by a 2-week washout and subsequent crossover for a second 8-week phase. The primary outcome was rate of symptomatic IDH. RESULTS Thirty-five participants entered, 32 were randomized, and 26 completed the study. The rate of symptomatic IDH with biofeedback was 0.10/h (95% confidence interval, 0.06 to 0.14) and 0.07/h (95% confidence interval, 0.05 to 0.10) during control (P=0.29). There were no differences in the rate or proportion of sessions with asymptomatic IDH or symptoms alone. Results remained consistent when adjusted for randomization order and study week. There were no differences between intervention and control in the last study week in interdialytic weight gain (difference [SD], -0.02 [0.8] kg), brain natriuretic peptide (1460 [19,052] ng/L), cardiac troponins (3 [86] ng/L), extracellular water-to-intracellular water ratio (0.05 [0.33]), ultrafiltration rate (1.1 [7.0] ml/kg per hour), and dialysis recovery time (0.43 [19.25] hours). CONCLUSION The use of blood volume monitoring-guided ultrafiltration biofeedback in patients prone to IDH did not reduce the rate of symptomatic IDH events.
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Affiliation(s)
| | | | - Pietro Ravani
- Departments of Medicine
- Community Health Sciences, and
| | - Henry Duff
- Departments of Medicine
- Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Jennifer M. MacRae
- Departments of Medicine
- Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada
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8
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Brodehl A, Williams T, Rezazadeh S, Munsie N, Duff H, Childs S, Gerull B. P1601Mutations in ILK (integrin linked kinase) are associated with human arrhythmogenic cardiomyopathy and decreased survival in zebrafish. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx502.p1601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- A. Brodehl
- Libin Cardiovascular Institute of Alberta - University of Calgary, Calgary, Canada
| | - T. Williams
- Comprehensive Heart Failure Center (CHFC), Internal Medicine, Wurzburg, Germany
| | - S. Rezazadeh
- Libin Cardiovascular Institute of Alberta - University of Calgary, Calgary, Canada
| | - N. Munsie
- University of Calgary, Department of Biochemistry and Molecular Biology, Calgary, Canada
| | - H. Duff
- Libin Cardiovascular Institute of Alberta - University of Calgary, Calgary, Canada
| | - S.J. Childs
- University of Calgary, Department of Biochemistry and Molecular Biology, Calgary, Canada
| | - B. Gerull
- Comprehensive Heart Failure Center (CHFC), Internal Medicine, Wurzburg, Germany
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9
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Duff H, Sheldon RS. Ankyrin-B Defects: Serendipity and Inquisitiveness are the Mothers of Invention. Circ Cardiovasc Genet 2017; 10:CIRCGENETICS.117.001698. [PMID: 28196903 DOI: 10.1161/circgenetics.117.001698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Affiliation(s)
- Henry Duff
- From the Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
| | - Robert S Sheldon
- From the Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada.
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10
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Alshehri M, Semeniuk L, Exner D, Mardell A, Zygun D, Sheldon R, Wagel S, Schnell G, Duff H. ABSENCE OF A J-WAVE MAY BE PREDICTIVE OF WORSE OUTCOMES DURING THERAPEUTIC HYPOTHERMIA IN POST CARDIAC ARREST PATIENTS. Can J Cardiol 2016. [DOI: 10.1016/j.cjca.2016.07.338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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11
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Rezazadeh S, Duff H. Dissociative States: hERG Channel (Kv11.1) Modulators That Enhance Dissociation of Drugs From Their Blocking Receptor. Circ Arrhythm Electrophysiol 2016; 9:e004003. [DOI: 10.1161/circep.116.004003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Saman Rezazadeh
- From the Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Henry Duff
- From the Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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12
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Hersi A, Giannoccaro JP, Howarth A, Exner D, Weeks S, Eitel I, Herman RC, Duff H, Ritchie D, Mcrae M, Sheldon R. Statin Induced Regression of Cardiomyopathy Trial: A Randomized, Placebo-controlled Double-blind Trial. Heart Views 2016; 17:129-135. [PMID: 28400935 PMCID: PMC5363087 DOI: 10.4103/1995-705x.201784] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Background: Hypertrophic cardiomyopathy (HCM), characterized by a thickened, fibrotic myocardium, remains the most common cause of sudden cardiac death in young adults. Based on animal and clinical data, we hypothesized that atorvastatin would induce left ventricular (LV) mass regression. Methods: Statin Induced Regression of Cardiomyopathy Trial (SIRCAT) was a randomized, placebo-controlled study. The primary endpoint was change in LV mass measured by cardiac magnetic resonance imaging 12 months after treatment with once-daily atorvastatin 80 mg or placebo. A key secondary endpoint was diastolic dysfunction measured echocardiographically by transmitral flow velocities. SIRCAT is registered with www.clinicaltrials.gov (NCT00317967). Results: Of 222 screened patients, 22 were randomized evenly to atorvastatin and placebo. The mean age was 47 ± 10 years, and 15 (68%) were male. All subjects completed the protocol. At baseline, LV masses were 197 ± 76 g and 205 ± 82 g in the placebo and atorvastatin groups, respectively. After 12 months treatment, the LV masses in the placebo and atorvastatin groups were 196 ± 80 versus 206 ± 92 g (P = 0.80), respectively. Echocardiographic indices were not different in the two groups at baseline. After 12 months, diastolic dysfunction as assessed using transmitral flow velocities E/E', A/A', and peak systolic mitral velocity showed no benefit from atorvastatin. Conclusions: In patients with HCM, atorvastatin did not cause LV mass regression or improvements in LV diastolic function.
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Affiliation(s)
- Ahmad Hersi
- Department of Cardiac Sciences, King Saud University Medical City, College of Medicine, Riyadh, Kingdom of Saudi Arabia
| | - J Peter Giannoccaro
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Andrew Howarth
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Derek Exner
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Sarah Weeks
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Ingo Eitel
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - R Cameron Herman
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Henry Duff
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Debbie Ritchie
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Maureen Mcrae
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Robert Sheldon
- Department of Cardiac Sciences, Libin Cardiovascular Institue of Alberta, University of Calgary, Calgary, Alberta, Canada
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Abstract
Introduction: Current National Institute for Health and Care Excellence (NICE) guidelines recommend the use of Low Molecular Weight Heparin (LMWH) for one month post-operatively in abdominal and pelvic cancer surgery to reduce risk of venous thromboembolism. We audited the prescription of LMWH at discharge and the compliance of patients with LMWH post-operatively and instigated measures to improve compliance. Materials and Methods: All patients undergoing major urological surgery from November 2011 to April 2012 were audited, with data collected on evidence of post-operative prescription (from discharge summaries). Patients within this 3-month period were questioned regarding compliance following discharge. Following this, changes were instigated to improve compliance (earlier discussion of post-operative LMWH administration in clinic, improved patient and junior doctor education). All patients undergoing surgery from November 2012 to June 2013 were identified and a re-audit completed. Results: Post-operative prescription of LMWH improved overall from 73% to 88%. Patient compliance to complete LMWH course improved from 23% to 88%. At re-audit, 97% of patients felt that training was adequate, and 94% of patients understood the rationale for taking LMWH at re-audit. Conclusion: Education of junior doctors improved prescription of LMWH at discharge. Improved patient education improves community LMWH use compliance post-discharge.
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Affiliation(s)
| | - E Upchurch
- Great Western Hospital, Swindon, England
| | - H Duff
- Derriford Hospital, England
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14
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Tan VH, Duff H, Gerull B, Sumner G. Early repolarization syndrome: A case report focusing on dynamic electrocardiographic changes before ventricular arrhythmias and genetic analysis. HeartRhythm Case Rep 2015; 1:213-216. [PMID: 28491551 PMCID: PMC5419330 DOI: 10.1016/j.hrcr.2015.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Vern Hsen Tan
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
- Cardiology Department, Changi General Hospital, Singapore
| | - Henry Duff
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
- Cardiology Department, Changi General Hospital, Singapore
| | - Brenda Gerull
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
| | - Glen Sumner
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
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15
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Teng G, Duff H, Belke D, Turnbull J, Meijndert C, Chen Y, O'Brien E, Fedak P. TETRANDRINE REVERSES HUMAN CARDIAC MYOFIBROBLAST ACTIVATION AND MYOCARDIAL FIBROSIS. Can J Cardiol 2014. [DOI: 10.1016/j.cjca.2014.07.159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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16
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Gerull B, Kuriachan V, Clegg R, Exner D, Ferrier R, Desmarais S, Gordon P, Duff H. Next-generation sequencing identifies multiple disease associated variants in inherited heart conditions. Eur Heart J 2013. [DOI: 10.1093/eurheartj/eht308.p2299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Roach D, Morck M, Sheldon R, Duff H. 632 Auto-Entrainment Risk Assessment in Heart Failure. Can J Cardiol 2012. [DOI: 10.1016/j.cjca.2012.07.569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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18
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Durdagi S, Deshpande S, Duff H, Noskov S. Development of Atomistic Models for Closed, Open and Open-Inactivated States of hERG1 Channel using Rosetta Protein Modeling Suite and Molecular Dynamics Simulations. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3693] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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19
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Marcus FI, Zareba W, Calkins H, Towbin JA, Basso C, Bluemke DA, Estes NAM, Picard MH, Sanborn D, Thiene G, Wichter T, Cannom D, Wilber DJ, Scheinman M, Duff H, Daubert J, Talajic M, Krahn A, Sweeney M, Garan H, Sakaguchi S, Lerman BB, Kerr C, Kron J, Steinberg JS, Sherrill D, Gear K, Brown M, Severski P, Polonsky S, McNitt S. Arrhythmogenic right ventricular cardiomyopathy/dysplasia clinical presentation and diagnostic evaluation: results from the North American Multidisciplinary Study. Heart Rhythm 2009; 6:984-92. [PMID: 19560088 DOI: 10.1016/j.hrthm.2009.03.013] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Accepted: 03/06/2009] [Indexed: 01/28/2023]
Abstract
BACKGROUND Prior reports on patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) focused on individuals with advanced forms of the disease. Data on the diagnostic performance of various testing modalities in newly identified individuals suspected of having ARVC/D are limited. OBJECTIVE The purpose of the Multidisciplinary Study of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia was to study the clinical characteristics and diagnostic evaluation of a large group of patients newly identified with ARVC/D. METHODS A total of 108 newly diagnosed patients with suspected ARVC/D were prospectively enrolled in the United States and Canada. The patients underwent noninvasive and invasive tests using standardized protocols that initially were interpreted by the enrolling center and adjudicated by blind analysis in six core laboratories. Patients were followed for a mean of 27 +/- 16 months (range 0.2-63 months). RESULTS The clinical profile of these newly diagnosed patients differs from the profile of reported patients with more advanced disease. There was considerable difference in the initial and final classification of the presence of ARVC/D after the diagnostic tests were evaluated by the core laboratories. Final clinical diagnosis was 73 affected, 28 borderline, and 7 unaffected. Individual tests agreed with the final diagnosis in 50% to 70% of the 73 patients with a final classification of affected. CONCLUSION The clinical profile of 108 newly diagnosed probands with suspected ARVC/D indicates that a combination of diagnostic tests is needed to evaluate the presence of right ventricular structural, functional, and electrical abnormalities. Echocardiography, right ventricular angiography, signal-averaged ECG, and Holter monitoring provide optimal clinical evaluation of patients suspected of ARVC/D.
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Affiliation(s)
- Frank I Marcus
- Section of Cardiology, University of Arizona, 1501 N. Campbell Avenue, Tucson, Arizona 85724-0001, USA.
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20
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Tandri H, Macedo R, Calkins H, Marcus F, Cannom D, Scheinman M, Daubert J, Estes M, Wilber D, Talajic M, Duff H, Krahn A, Sweeney M, Garan H, Bluemke DA. Role of magnetic resonance imaging in arrhythmogenic right ventricular dysplasia: insights from the North American arrhythmogenic right ventricular dysplasia (ARVD/C) study. Am Heart J 2008; 155:147-53. [PMID: 18082506 DOI: 10.1016/j.ahj.2007.08.011] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Accepted: 08/12/2007] [Indexed: 12/18/2022]
Abstract
BACKGROUND Prior reports describing magnetic resonance (MR) imaging abnormalities in arrhythmogenic right ventricular dysplasia (ARVD/C) were limited by nonuniform inclusion criteria. The aim of our study was to define the prevalence, sensitivity, and specificity of quantitative MR imaging findings in the probands of multidisciplinary study of right ventricular dysplasia. METHODS Individuals with ventricular arrhythmias of left bundle-branch block morphology meeting the Task Force criteria for ARVD/C underwent MR imaging. The MR images were compared with 10 patients with idiopathic ventricular tachycardia (VT) and 25 controls. Of the 42 study probands, 40 met the Task Force criteria exclusive of MR imaging findings. All MR images were interpreted in a blinded fashion. RESULTS Right ventricle fat infiltration was reported in 24 (60%) probands and none of the patients with idiopathic VT or controls. Six patients (15%) had fat infiltration of the left ventricle. Right ventricle regional dysfunction was observed in 32 probands (80%) and none of the patients with idiopathic VT or controls. Qualitative RV function was abnormal in 26 probands (60%); however, quantitative RV ejection fraction was abnormal in 85% (24/28) of the probands. An RV ejection fraction <50% had a sensitivity of 73% and a specificity of 95% in diagnosis of ARVD/C. CONCLUSIONS Fat infiltration is seldom the only MR imaging abnormality and is less sensitive for ARVD/C diagnosis compared with RV regional dysfunction. Qualitative estimates of RV function may underestimate the prevalence of RV dysfunction in ARVD/C. Quantitative evaluation of RV by MR imaging may have a high sensitivity and specificity for ARVD/C diagnosis.
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Affiliation(s)
- Harikrishna Tandri
- Department of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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21
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Roach D, Koshman ML, Duff H, Sheldon R. Similarity of spontaneous and induced heart rate and blood pressure turbulence. Can J Cardiol 2003; 19:1375-9. [PMID: 14631471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
BACKGROUND Heart rate turbulence (HRT) is a transient tachycardia-bradycardia that follows premature ventricular complexes (PVCs). The physiology of turbulence is studied in the electrophysiology lab using induced premature ventricular stimuli but the reliability of this model for HRT is unknown. OBJECTIVES To compare heart rate and blood pressure signatures of induced and spontaneous HRT. METHODS Each patient received 10 ventricular extrastimuli at 1-min intervals. Electrocardiogram and continuous blood pressure results were digitized for 34 electrophysiology patients. RESULTS Fifteen patients yielded at least one induced and one spontaneous analyzable PVC. Per subject, 3.6+/-2.2 spontaneous and 6.1+/-3.3 induced HRT sequences were detected. Spontaneous and inducible HRT were indistinguishable according to turbulence onset (median -1.7% versus -2.3%, P=0.09), turbulence slope (median 7.1 ms/beat versus 10.0 ms/beat, P=0.73), turbulence tachycardia (median 29 ms versus 22 ms, P=0.97) and turbulence bradycardia (45 ms versus 72 ms, P=0.60). Accompanying blood pressure signatures were indistinguishable according to initial hypotension (-0.5+/-5.9 mmHg versus 12.1+/-5.5 mmHg, P=0.19), hypertension time (7.7+/-3.6 s versus 7.8+/-1.9 s, P=0.93) and turbulence hypertension (13.5+/-5.7 mmHg versus 16.1+/-9.2 mmHg, P=0.19). Baroreflex sensitivities estimated by the spontaneous sequence method were similar for spontaneous and induced turbulence (median 7.5 ms/mmHg versus 7.2 ms/mmHg, P=0.89) and correlated with each other (r2=0.81). Heart rate and blood pressure turbulence induced in the electrophysiology laboratory were similar to those following spontaneous PVCs and induced turbulence was a valid model for study under controlled conditions.
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Affiliation(s)
- Daniel Roach
- Cardiovascular Research Group, University of Calgary, Calgary, Alberta, Canada
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22
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Abstract
Heart rate turbulence (HRT) is a transient tachycardia and/or bradycardia that follows ventricular premature complexes (VPCs). Absent or blunted HRT is associated with a poor prognosis in patients with heart disease, but its physiology is unknown. We hypothesized that HRT might be mediated by baroreflexes following early depolarizations. We sought to induce and characterize HRT in the electrophysiologic laboratory by introducing 1 ventricular extrastimulus every 60 seconds in 23 patients who underwent invasive electrophysiologic studies. On average, HRT was characterized by an initial RR interval decrease of 38 ms occurring 3.4 seconds after early depolarization. This was followed by a transient RR interval increase of 88 ms occurring 5.4 seconds later. HRT was preceded by similar hypotensive and/or hypertensive blood pressure turbulence. Baroreflex sensitivity estimates from post-VPCs and sinus sequences were similar (12.3 +/- 10.3 vs 10.2 +/- 8.9 ms/mm Hg, p = 0.51). The failure to induce HRT was associated with a limited initial hypotensive phase of blood pressure turbulence (-7.9 vs -12.1 mm Hg, p = 0.037). Patients with structural heart disease had reduced turbulence onset and reduced turbulence slope relative to those with structurally normal hearts, although blood pressure response was similar in both groups. HRT is an inducible, transient tachycardia and/or bradycardia that likely arises from a baroreflex response to transient hypotension following VPCs. Patients with structural heart disease have blunted HRT.
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Affiliation(s)
- Daniel Roach
- Cardiovascular Research Group, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada
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23
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Hallstrom AP, McAnulty JH, Wilkoff BL, Follmann D, Raitt MH, Carlson MD, Gillis AM, Shih HT, Powell JL, Duff H, Halperin BD. Patients at lower risk of arrhythmia recurrence: a subgroup in whom implantable defibrillators may not offer benefit. Antiarrhythmics Versus Implantable Defibrillator (AVID) Trial Investigators. J Am Coll Cardiol 2001; 37:1093-9. [PMID: 11263614 DOI: 10.1016/s0735-1097(00)01208-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES The goal of this study was to identify subgroups of arrhythmia patients who do not benefit from use of the implantable cardiac defibrillator (ICD). BACKGROUND Treatment of serious ventricular arrhythmias has evolved toward more common use of the ICD. Since estimates of the cost per year of life saved by ICD therapy vary from $25,000 to perhaps $125,000, it is important to identify patient subgroups that do not benefit from the ICD. METHODS Data for 491 ICD patients enrolled in the Antiarrhythmics Versus Implantable Defibrillators Study were used to create a hazards model relating baseline factors to time to first recurrent arrhythmia. The model was used to predict the hazard for recurrent arrhythmia among all trial patients. A priori cut points provided lower and higher recurrent arrhythmia risk strata. For each stratum the incremental years of life due to ICD versus antiarrhythmic drug therapy were calculated. RESULTS Factors that predicted recurrent arrhythmia were: ventricular tachycardia as the index arrhythmia, history of cerebrovascular disease, lower left ventricular ejection fraction, a history of any tachyarrhythmia before the index event and the absence of revascularization after the index event. Survival times (over a follow-up of three years) were identical in each arm of the lowest risk sextile (survival advantage 0.03 +/- 0.12 [se] years), while the survival advantage for patients above the first sextile was 0.27 +/- 0.07 (se) years (two-sided p = 0.05). CONCLUSIONS Patients presenting with an isolated episode of ventricular fibrillation in the absence of cerebrovascular disease or history of prior arrhythmia who have undergone revascularization or who have moderately preserved left ventricular function (left ventricular ejection fraction > 0.27) are not likely to benefit from ICD therapy compared with amiodarone therapy.
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24
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Abstract
Developmental changes in electrocardiogram (ECG) and response to selective K(+) channel blockers were assessed in conscious, unsedated neonatal (days 1, 7, 14) and adult male mice (>60 days of age). Mean sinus R-R interval decreased from 120 +/- 3 ms in day 1 to 110 +/- 3 ms in day 7, 97 +/- 3 ms in day 14, and 81 +/- 1 ms in adult mice (P < 0.001 by ANOVA; all 3 groups different from day 1). In parallel, the mean P-R interval progressively decreased during development. Similarly, the mean Q-T interval decreased from 62 +/- 2 ms in day 1 to 50 +/- 2 ms in day 7, 47 +/- 8 ms in day 14 neonatal mice, and 46 +/- 2 ms in adult mice (P < 0.001 by ANOVA; all 3 groups are significantly different from day 1). Q-T(c) was calculated as Q- interval. Q-T(c) significantly shortened from 179 +/- 4 ms in day 1 to 149 +/- 5 ms in day 7 mice (P < 0.001). In addition, the J junction-S-T segment elevation observed in day 1 neonatal mice resolved by day 14. Dofetilide (0.5 mg/kg), the selective blocker of the rapid component of the delayed rectifier (I(Kr)) abolished S-T segment elevation and prolonged Q-T and Q-T(c) intervals in day 1 neonates but not in adult mice. In contrast, 4-aminopyridine (4-AP, 2.5 mg/kg) had no effect on day 1 neonates but in adults prolonged Q-T and Q-T(c) intervals and specifically decreased the amplitude of a transiently repolarizing wave, which appears as an r' wave at the end of the apparent QRS in adult mice. In conclusion, ECG intervals and configuration change during normal postnatal development in the mouse. K(+) channel blockers affect the mouse ECG differently depending on age. These data are consistent with the previous findings that the dofetilide-sensitive I(Kr) is dominant in day 1 mice, whereas 4-AP-sensitive currents, the transiently repolarizing K(+) current, and the rapidly activating, slowly inactivating K(+) current are the dominant K(+) currents in adult mice. This study provides background information useful for assessing abnormal development in transgenic mice.
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Affiliation(s)
- L Wang
- Department of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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25
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Abstract
BACKGROUND Quinine is the diastereomer of quinidine. In dogs, it has similar effects on conduction time but does not prolong epicardial repolarization time or ventricular refractoriness. It has antiarrhythmic effects in both cats and dogs. We assessed the antiarrhythmic potential of quinine in suppressing ventricular arrhythmias in humans. METHODS AND RESULTS Patients underwent open-label, dose-ranging trials of quinine with daily doses of 600, 1200, and 1800 mg in a twice-daily dosing regimen. In 17 patients with frequent spontaneous ventricular ectopy, oral quinine suppressed arrhythmia in 11 of 12 patients who finished the study and was not tolerated by 4 patients, and 1 patient withdrew from the study. The mean effective daily dosage was 927 mg, the mean effective trough serum level was 11 mumol/L (range, 4 to 17 mumol/L), and the half-life was 20 +/- 7 hours. In a second open-label, dose-ranging trial in 10 patients with inducible ventricular tachycardia and reduced left ventricular systolic function (left ventricular ejection fraction, 35 +/- 16%), quinine suppressed inducibility of ventricular tachycardia in 3 of 10 patients. At a basic pacing cycle length of 500 milliseconds, ventricular effective refractory period was prolonged (279 +/- 21 versus 247 +/- 10 milliseconds, quinine versus drug free, P = .003). In the remaining patients, ventricular tachycardia cycle length was prolonged (373 +/- 48 versus 253 +/- 30 milliseconds, quinine versus drug free, P < .001). The corrected QT interval was not prolonged. CONCLUSIONS Quinine is an effective and convenient antiarrhythmic drug for the suppression of ventricular arrhythmias in humans.
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Affiliation(s)
- R Sheldon
- Cardiovascular Research Group, University of Calgary, Alberta, Canada
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27
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Sheldon R, Thakore E, Wilson L, Duff H. Interaction of drug metabolites with the class I antiarrhythmic drug receptor on rat cardiac myocytes. J Pharmacol Exp Ther 1994; 269:477-81. [PMID: 8182514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The use of class I antiarrhythmic drugs may be complicated by the presence of active metabolites. A simple technique to predict the clinical activity of these metabolites might help with the clinical use of these drugs. We tested the hypothesis that drug metabolites bind to the class I drug receptor, but that only clinically active metabolites bind appreciably at clinically observed concentrations. Using a radioligand assay, we determined whether 13 class I drug metabolites interacted with a receptor for class I drugs associated with the cardiac sodium channel. The radioligand was [3H]batrachotoxinin A20 benzoate. All 13 metabolites bound to the drug receptor with IC50 values of 2.7 to 375 microns, and a mean Hill number of 1.0 +/- 0.3. All of the seven active metabolites (N-acetylprocainamide, mono-N-dealkyldisopyramide, 5-hydroxypropafenone, N-desisopropylpropafenone, 0-demethylencainide, 3-methoxy-0-demethylencainide and desethylamiodarone) each bound to the receptor at concentrations approaching their clinical concentrations, whereas none of the six inactive metabolites (quinidine-N-oxide, 3-hydroxyquinidine, glycinexylidide, monoethylglycinexylidide, N-demethylencainide and N,0-demethylencainide) did. Using a relationship which correlates drug IC50 values and clinically observed drug concentrations we calculated predicted clinical concentrations if the metabolites were clinically active. A predicted/observed ratio < or = 10 correlates with 100% positive and negative accuracies whether a drug metabolite has clinical activity. Thus a simple radioligand assay predicts whether class I drugs have clinical activity.
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Affiliation(s)
- R Sheldon
- Cardiovascular Research Group, University of Calgary, Alberta, Canada
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28
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Abstract
The pharmacokinetics of a single intravenous dose of propafenone were studied in subjects with normal renal function (n = 5), renal insufficiency (n = 5), and renal failure (n = 3). No difference in central volume of distribution, total ischemic clearance or terminal half-life existed. None of the pharmacokinetic parameters examined correlated to creatinine clearance. Within the confines of the small number of patients studied, there does not appear to be any effect of renal insufficiency or failure on single-dose propafenone disposition.
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Affiliation(s)
- E Burgess
- Department of Medicine, University of Calgary, Alberta, Canada
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29
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Abstract
A RIA for alpha-human atrial natriuretic peptide (alpha hANP) in plasma was developed and used to study the immunoreactive components secreted by the heart and circulating in peripheral venous plasma. The assay used [125I]diiodotyrosyl-alpha hANP, purified by high pressure liquid chromatography (HPLC), and a C-terminal-specific antiserum purchased from Peninsula Laboratories. Serial dilution curves of coronary sinus plasma samples were parallel with the standard curve, but significant nonparallelism was found in peripheral plasma samples of low immunoreactivity. When plasma was extracted using C-18 Sep-Pak cartridges, serial dilution curves from both coronary sinus and peripheral plasma samples were parallel to the standard curve. Although values for plasma samples assayed before and after extraction agreed closely (r = 0.99; n = 76), immunoreactive ANP in unextracted plasma was consistently greater (70-79 pmol/liter) than in extracts of plasma, suggesting non-specific interference by a component in plasma when assayed without extraction. Mean plasma immunoreactive ANP in 19 normal subjects consuming a normal salt intake was 14 +/- 1 (+/- SE) pmol/liter. In 5 normal men, increasing dietary sodium intake from 10 to 200 mmol sodium/day was associated with a 2-fold increment in ANP levels, and similar changes accompanied acute sodium loading using iv saline. Elevated values were found in patients with congestive heart failure (mean, 58 pmol/liter; range, 0-200; n = 9), chronic renal failure (mean, 118 pmol/liter; range, 30-290; n = 8), and primary aldosteronism (range, 32-90 pmol/liter; n = 3). HPLC and gel chromatographic analysis of the immunoreactive material found in coronary sinus plasma extracts showed that a large amount of the material eluted in the position of alpha hANP. A smaller quantity of immunoreactive material with a mol wt of about 1600 was also identified. Peripheral venous plasma extracts also contained several immunoreactive components, the largest amount of which corresponded to alpha hANP. The pattern of immunoreactive components in peripheral venous plasma, as identified by both gel chromotography and HPLC, was similar to that in coronary sinus plasma drawn during an active phase of hormone secretion. These findings indicate that the heart secretes alpha hANP or a closely similar peptide which is also present in peripheral venous plasma. Plasma immunoreactive ANP is responsive to sodium loading in normal man and is elevated in patients with hypervolemic disorders.
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30
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Duff H, Renouf P, Macgregor DC, McLaughlin PR. Valve replacement for isolated mitral regurgitation. Can J Surg 1980; 23:141-5. [PMID: 7363174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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