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Prolong Qt

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https://www.readbyqxmd.com/read/28429460/automated-t-wave-analysis-can-differentiate-acquired-qt-prolongation-from-congenital-long-qt-syndrome
#1
Alan Sugrue, Peter A Noseworthy, Vaclav Kremen, J Martijn Bos, Bo Qiang, Ram K Rohatgi, Yehu Sapir, Zachi I Attia, Peter Brady, Pedro J Caraballo, Samuel J Asirvatham, Paul A Friedman, Michael J Ackerman
BACKGROUND: Prolongation of the QT on the surface electrocardiogram can be due to either genetic or acquired causes. Distinguishing congenital long QT syndrome (LQTS) from acquired QT prolongation has important prognostic and management implications. We aimed to investigate if quantitative T-wave analysis could provide a tool for the physician to differentiate between congenital and acquired QT prolongation. METHODS: Patients were identified through an institution-wide computer-based QT screening system which alerts the physician if the QTc ≥ 500 ms...
April 21, 2017: Annals of Noninvasive Electrocardiology
https://www.readbyqxmd.com/read/28421417/estimation-of-qt-interval-prolongation-through-model-averaging
#2
Peter L Bonate
The current method to analyze concentration-QT interval data, which is based on predictions conditional on a best model, fails to take into account the uncertainty of the model. Previous studies have suggested that failure to take into account model uncertainty using a best model approach can result in confidence intervals that are overly optimistic and may be too narrow. Theoretically, more realistic estimates are obtained using model-averaging where the overall point estimate and confidence interval are a weighted-average from a set of candidate models, the weights of which are equal to each model's Akaike weight...
April 18, 2017: Journal of Pharmacokinetics and Pharmacodynamics
https://www.readbyqxmd.com/read/28419650/cardiovascular-safety-in-refractory-incontinent-patients-with-overactive-bladder-receiving-add-on-mirabegron-therapy-to-solifenacin-beside
#3
Marcus J Drake, Scott MacDiarmid, Christopher R Chapple, Adil Esen, Stavros Athanasiou, Javier Cambronero Santos, David Mitcheson, Sender Herschorn, Emad Siddiqui, Moses Huang, Matthias Stoelzel
AIMS/OBJECTIVES: In the BESIDE study, combination therapy (antimuscarinic [solifenacin] and β3 -adrenoceptor agonist [mirabegron]) improved efficacy over solifenacin monotherapy without exacerbating anticholinergic side effects in overactive bladder (OAB) patients; however, a potential synergistic effect on the cardiovascular (CV) system requires investigation. METHODS: OAB patients remaining incontinent despite daily solifenacin 5 mg during 4-week single-blind run-in, were randomised 1:1:1 to double-blind daily combination (solifenacin 5 mg/mirabegron 25 mg, increasing to 50 mg after week 4), solifenacin 5 or 10 mg for 12 weeks...
April 16, 2017: International Journal of Clinical Practice
https://www.readbyqxmd.com/read/28419455/human-electrical-muscular-incapacitation-and-effects-on-qtc-interval
#4
John A Gibbons, Andrew J Mojica, Mark E Peele
Human Electrical Muscular Incapacitation (HEMI) is used to subdue combative individuals. Changes in cardiac electrical activity have been proposed as the cause of death in a small fraction of these individuals. The current study sought to determine whether changes in QTc interval occur after HEMI exposure. Twenty-four participants had EKG readings before a 5-second HEMI exposure and within 30 min after exposure. All subject EKGs were read by a data-blinded cardiac electrophysiologist who calculated a QT corrected (QTc) interval...
April 17, 2017: Journal of Forensic Sciences
https://www.readbyqxmd.com/read/28417026/cardiovascular-complications-of-acute-amphetamine-abuse-cross-sectional-study
#5
Elham Bazmi, Farinaz Mousavi, Leila Giahchin, Tahmineh Mokhtari, Behnam Behnoush
OBJECTIVES: This study aimed to evaluate cardiovascular complications among patients who abuse amphetamines. METHODS: This cross-sectional study took place between April 2014 and April 2015 among 3,870 patients referred to the Toxicology Emergency Department of Baharlou Hospital, Tehran University of Medical Sciences, Tehran, Iran. Those with clinical signs of drug abuse and positive urine screening tests were included in the study, while cases of chronic abuse were excluded...
February 2017: Sultan Qaboos University Medical Journal
https://www.readbyqxmd.com/read/28408648/azithromycin-causes-a-novel-proarrhythmic-syndrome
#6
Zhenjiang Yang, Joseph K Prinsen, Kevin R Bersell, Wangzhen Shen, Liudmila Yermalitskaya, Tatiana Sidorova, Paula B Luis, Lynn Hall, Wei Zhang, Liping Du, Ginger Milne, Patrick Tucker, Alfred L George, Courtney M Campbell, Robert A Pickett, Christian M Shaffer, Nagesh Chopra, Tao Yang, Bjorn C Knollmann, Dan M Roden, Katherine T Murray
BACKGROUND: The widely used macrolide antibiotic azithromycin increases risk of cardiovascular and sudden cardiac death, although the underlying mechanisms are unclear. Case reports, including the one we document here, demonstrate that azithromycin can cause rapid, polymorphic ventricular tachycardia in the absence of QT prolongation, indicating a novel proarrhythmic syndrome. We investigated the electrophysiological effects of azithromycin in vivo and in vitro using mice, cardiomyocytes, and human ion channels heterologously expressed in human embryonic kidney (HEK 293) and Chinese hamster ovary (CHO) cells...
April 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28408211/cardiac-voltage-gated-ion-channels-in-safety-pharmacology-review-of-the-landscape-leading-to-the-cipa-initiative
#7
REVIEW
Hai Huang, Michael K Pugsley, Bernard Fermini, Michael J Curtis, John Koerner, Michael Accardi, Simon Authier
Voltage gated ion channels are central in defining the fundamental properties of the ventricular cardiac action potential (AP), and are also involved in the development of drug-induced arrhythmias. Many drugs can inhibit cardiac ion currents, including the Na(+) current (INa), L-type Ca(2+) current (Ica-L), and K(+) currents (Ito, IK1, IKs, and IKr), and thereby affect AP properties in a manner that can trigger or sustain cardiac arrhythmias. Since publication of ICH E14 and S7B over a decade ago, there has been a focus on drug effects on QT prolongation clinically, and on the rapidly activating delayed rectifier current (IKr), nonclinically, for evaluation of proarrhythmic risk...
April 10, 2017: Journal of Pharmacological and Toxicological Methods
https://www.readbyqxmd.com/read/28407402/cirrhotic-cardiomyopathy-implications-for-liver-transplantation
#8
REVIEW
Hongqun Liu, Saumya Jayakumar, Mouhieddin Traboulsi, Samuel S Lee
The majority of the patients on a waiting list for liver transplantation have end-stage liver disease. Due to the marked peripheral vasodilatation of end stage cirrhosis that masks a latent myocardial dysfunction, cardiac abnormalities in the resting state are usually subclinical and escape the attention of physicians. However, when challenged, the systolic and diastolic contractile responses are attenuated. In addition to these contractile abnormalities, morphological changes such as enlargement or hypertrophy of cardiac chambers and electrophysiological repolarization changes including a prolonged QT interval can be observed...
April 13, 2017: Liver Transplantation
https://www.readbyqxmd.com/read/28407228/deleterious-protein-altering-mutations-in-the-scn10a-voltage-gated-sodium-channel-gene-are-associated-with-prolonged-qt
#9
Maen D Abou Ziki, Sara B Seidelmann, Emily Smith, Gourg Atteya, Yuexin Jiang, Rodolfo Gil Fernandes, Mark A Marieb, Joseph G Akar, Arya Mani
Long QT syndrome (LQT) is a pro-arrhythmogenic condition with life threatening complications. Fifteen genes have been associated with congenital LQT however, the genetic causes remain unknown in more than 20% of cases. Eighteen patients with history of palpitations, presyncope, syncope and prolonged QT were referred to the Yale Cardiovascular Genetics Program. All subjects underwent whole exome sequencing (WES) followed by confirmatory Sanger sequencing. Mutation burden analysis was carried out using WES data from sixteen subjects with no identifiable cause of LQT...
April 13, 2017: Clinical Genetics
https://www.readbyqxmd.com/read/28403766/controversies-in-diagnosis-and-management-of-community-acquired-pneumonia
#10
REVIEW
Sarah Sparham, Patrick Gp Charles
Community-acquired pneumonia (CAP) is a common condition; however, it appears to be overdiagnosed. Diagnosing CAP too frequently may be adding to the problems of overuse of antibiotics, such as bacterial resistance in the community and greater costs and complications in individuals. Data support that most patients with non-severe CAP can be treated for 3-5 days; however, most patients with CAP are receiving much longer courses of therapy. Macrolides such as azithromycin have the potential to prolong the QT interval, although large population studies show that this does not appear to result in excess cardiac mortality...
April 17, 2017: Medical Journal of Australia
https://www.readbyqxmd.com/read/28394491/randomized-blinded-placebo-and-positive-controlled-crossover-study-to-determine-the-effect-of-deferiprone-on-the-qtc-interval-in-healthy-subjects
#11
Caroline Fradette, Anna Rozova, Anne Stilman, Yu Chung Tsang, Mark J Allison, Fernando Tricta
This study evaluated whether deferiprone, an oral iron chelator, acts to prolong the QT interval. Fifty healthy volunteers received single doses of each of the following: therapeutic dose of deferiprone (33 mg/kg), supratherapeutic dose (50 mg/kg), placebo, or moxifloxacin, a positive control known to significantly prolong QT interval. Following each dose, subjects underwent cardiac monitoring, pharmacokinetics assessments, and safety assessments. Based on the QT interval obtained using the Fridericia correction for heart rate (QTcF), the upper bound of the 1-sided 95% confidence interval of the mean difference between deferiprone and placebo was <10 milliseconds (the threshold of concern defined by authorities) at all time points for both doses: maximum difference of 3...
April 10, 2017: Clinical Pharmacology in Drug Development
https://www.readbyqxmd.com/read/28394409/evaluation-of-qtc-in-rett-syndrome-correlation-with-age-severity-and-genotype
#12
Jane Crosson, Siddharth Srivastava, Genila M Bibat, Siddharth Gupta, Aditi Kantipuly, Constance Smith-Hicks, Scott M Myers, Abanti Sanyal, Gayane Yenokyan, Joel Brenner, Sakkubai R Naidu
Rett syndrome (RTT) is caused by MECP2 mutations, resulting in various neurological symptoms. Prolonged corrected QT interval (QTc) is also reported and is a speculated cause of sudden death in RTT. The purpose of this study was to correlate QTc in RTT patients with age, clinical severity, and genotype. 100 RTT patients (98 females, 2 males) with MECP2 mutations underwent baseline neurological evaluation (KKI-RTT Severity Scale) and QTc measurement (standard 12 lead electrocardiogram) as part of our prospective natural history study...
April 10, 2017: American Journal of Medical Genetics. Part A
https://www.readbyqxmd.com/read/28392510/how-should-we-treat-school-aged-children-with-borderline-qt-prolongation
#13
Seiko Ohno
No abstract text is available yet for this article.
April 7, 2017: Circulation Journal: Official Journal of the Japanese Circulation Society
https://www.readbyqxmd.com/read/28382321/electrophysiological-mechanisms-of-long-and-short-qt-syndromes
#14
REVIEW
Gary Tse, Yin Wah Fiona Chan, Wendy Keung, Bryan P Yan
The QT interval on the human electrocardiogram is normally in the order of 450 ms, and reflects the summated durations of action potential (AP) depolarization and repolarization of ventricular myocytes. Both prolongation and shortening in the QT interval have been associated with ventricular tachy-arrhythmias, which predispose affected individuals to sudden cardiac death. In this article, the molecular determinants of the AP duration and the causes of long and short QT syndromes (LQTS and SQTS) are explored...
March 2017: IJC Heart & Vasculature
https://www.readbyqxmd.com/read/28377800/evaluation-of-tp-e-interval-tp-e-qt-ratio-and-tp-e-qtc-ratio-in-patients-with-subclinical-hypothyroidism
#15
Ahmet Gürdal, Hatice Eroğlu, Füsun Helvaci, Mutlu Çağan Sümerkan, Kamber Kasali, Şükrü Çetin, Gökhan Aksan, Kadriye Kiliçkesmez
BACKGROUND: Prolongation of the peak-to-end interval of the T wave (Tp-e) has been reported as associated with ventricular arrhythmias. The aim of this study was to investigate the ventricular repolarization by using the Tp-e interval, Tp-e/QT ratio and Tp-e/ QTc ratio in patients with subclinical hypothyroidism (SH). METHODS: We studied 56 volunteers: These were 28 patients with SH (mean age 45 ± 11 years) and 28 healthy subjects (mean age 34 ± 8 years). All basic biochemical parameters were analyzed and electrocardiograms (ECGs) were recorded...
March 2017: Therapeutic Advances in Endocrinology and Metabolism
https://www.readbyqxmd.com/read/28376710/electrocardiographic-changes-mimicking-acute-coronary-syndrome-in-a-large-intracranial-tumour-a-diagnostic-dilemma
#16
Nilukshana Yogendranathan, H M M T B Herath, S P Pahalagamage, Aruna Kulatunga
BACKGROUND: ST elevation Myocardial infarction is a medical emergency. A variety of noncardiac conditions had been known to mimic the ECG changes that are seen in acute coronary syndrome. Although the common ECG changes that are documented with raised intracranial pressure are T inversions, prolongation of QT interval and sinus bradycardia, ST elevation or depression, arrhythmias and prominent U waves have also been recognized. However, ST elevations in association with primary intracranial tumours are rarely reported...
April 4, 2017: BMC Cardiovascular Disorders
https://www.readbyqxmd.com/read/28371864/a-multicentre-study-of-patients-with-timothy-syndrome
#17
Mark A Walsh, Christian Turner, Katherine W Timothy, Neil Seller, Dominic L Hares, Andrew F James, Jules C Hancox, Orhan Uzun, Dean Boyce, Alan G Stuart, Paul Brennan, Caroline Sarton, Karen McGuire, Ruth A Newbury-Ecob, Karen Mcleod
Aims: Timothy syndrome (TS) is an extremely rare multisystem disorder characterized by marked QT prolongation, syndactyly, seizures, behavioural abnormalities, immunodeficiency, and hypoglycaemia. The aim of this study was to categorize the phenotypes and examine the outcomes of patients with TS. Methods and results: All patients diagnosed with TS in the United Kingdom over a 24-year period were reviewed. Fifteen centres in the British Congenital Arrhythmia Group network were contacted to partake in the study...
March 24, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28369767/multiple-targets-for-flecainide-action-implications-for-cardiac-arrhythmogenesis
#18
REVIEW
Samantha C Salvage, Karthik H Chandrasekharan, Kamalan Jeevaratnam, Angela F Dulhunty, Andrew J Thompson, Antony P Jackson, Christopher L-H Huang
Flecainide suppresses cardiac tachyarrhythmias including paroxysmal atrial fibrillation, supraventricular tachycardia, arrhythmic long QT syndromes (LQTS), as well as the Ca(2+) -mediated, catecholaminergic polymorphic ventricular, tachycardia (CPVT). However, flecainide can also exert pro-arrhythmic effects most notably following myocardial infarction and when used to diagnose Brugada Syndrome (BrS). These divergent actions result from its physiological and pharmacological actions at multiple, interacting, levels of cellular organisation...
April 3, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28367166/the-effect-of-glucose-variability-on-qtc-duration-and-dispersion-in-patients-with-type-2-diabetes-mellitus
#19
Yasar Sertbas, Ali Ozdemir, Meltem Sertbas, Akin Dayan, Seda Sancak, Cihangir Uyan
OBJECTIVE: Glycemic variability (GV) is a new term with the episodes of hyper and hypoglycemia in diabetic patients. Both prolonged QT interval and QTd are potential risk factors for malignant ventricular arrhythmias affecting the mortality of different groups of patients including diabetes mellitus. In this study, we aimed to evaluate if the glucose variability increasing the QTc interval and QTc dispersion in type 2 diabetes mellitus. METHODS: We included 275 consecutive patients with type 2 diabetes...
January 2017: Pakistan Journal of Medical Sciences Quarterly
https://www.readbyqxmd.com/read/28366778/incidence-and-significance-of-acquired-qt-interval-prolongation-in-hospitalized-patients
#20
EDITORIAL
James E Tisdale
No abstract text is available yet for this article.
March 30, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
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