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QTc interval

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https://www.readbyqxmd.com/read/28213753/electrophysiologic-studies-on-the-risks-and-potential-mechanism-underlying-the-proarrhythmic-nature-of-azithromycin
#1
Mengdan Zhang, Ming Xie, Sha Li, Ying Gao, Shuyin Xue, Huili Huang, Kesu Chen, Fuming Liu, Long Chen
The mechanisms underlying arrhythmia induced by the clinical use of azithromycin are poorly understood. We aimed to investigate the proarrhythmic effects of azithromycin using electrocardiogram (ECG) and ion channel models. In vivo and in vitro guinea pig ECG and current and voltage clamp recordings were carried out. Azithromycin at 114.6 mg/kg (three times the clinically relevant dose) reduced heart rate (HR) and prolonged the PR, QRS and rate-corrected QT (QTc) intervals of guinea pig ECG in vivo. In vitro technique revealed that azithromycin at 207...
February 17, 2017: Cardiovascular Toxicology
https://www.readbyqxmd.com/read/28213480/a-common-genetic-variant-risk-score-is-associated-with-drug-induced-qt-prolongation-and-torsade-de-pointes-risk-a-pilot-study
#2
David G Strauss, Jose Vicente, Lars Johannesen, Ksenia Blinova, Jay W Mason, Peter Weeke, Elijah R Behr, Dan M Roden, Raymond Woosley, Gulum Kosova, Michael A Rosenberg, Christopher Newton-Cheh
Background -Drug-induced QT interval prolongation, a risk factor for life-threatening ventricular arrhythmias, is a potential side effect of many marketed and withdrawn medications. The contribution of common genetic variants previously associated with baseline QT interval to drug-induced QT prolongation and arrhythmias is not known. Methods -We tested the hypothesis that a weighted combination of common genetic variants contributing to QT interval at baseline, identified through genome-wide association studies, can predict individual response to multiple QT-prolonging drugs...
February 17, 2017: Circulation
https://www.readbyqxmd.com/read/28213374/diurnal-differences-in-risk-of-cardiac-arrhythmias-during-spontaneous-hypoglycemia-in-young-people-with-type-1-diabetes
#3
Peter Novodvorsky, Alan Bernjak, Elaine Chow, Ahmed Iqbal, Lianne Sellors, Scott Williams, Robert A Fawdry, Bhavin Parekh, Richard M Jacques, Jefferson L B Marques, Paul J Sheridan, Simon R Heller
OBJECTIVE: Hypoglycemia may exert proarrhythmogenic effects on the heart via sympathoadrenal stimulation and hypokalemia. Hypoglycemia-induced cardiac dysrhythmias are linked to the "dead-in-bed syndrome," a rare, but devastating, condition. We examined the effect of nocturnal and daytime clinical hypoglycemia on electrocardiogram (ECG) in young people with type 1 diabetes. RESEARCH DESIGN AND METHODS: Thirty-seven individuals with type 1 diabetes underwent 96 h of simultaneous ambulatory ECG and blinded continuous interstitial glucose monitoring (CGM) while symptomatic hypoglycemia was recorded...
February 17, 2017: Diabetes Care
https://www.readbyqxmd.com/read/28212739/individualized-corrected-qt-interval-is-superior-to-qt-interval-corrected-using-the-bazett-formula-in-predicting-mutation-carriage-in-families-with-long-qt-syndrome
#4
Tomas Robyns, Rik Willems, Bert Vandenberk, Joris Ector, Christophe Garweg, Cuno Kuiperi, Jeroen Breckpot, Anniek Corveleyn, Stefan Janssens, Hein Heidbuchel, Dieter Nuyens
BACKGROUND: Long QT syndrome (LQTS) is characterized by reduced penetrance and variable QT prolongation over time, resulting in an estimate of 25% carriers of a pathogenic mutation with a normal corrected QT (QTc) interval on the resting electrocardiogram (ECG). OBJECTIVE: The purpose of this study was to test the hypothesis that an individualized corrected QT interval derived from 24-hour Holter data more accurately predicts carriage of a pathogenic LQTS mutation than did QT derived from a standard 12-lead ECG and corrected using the Bazett formula (QTc interval)...
March 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28211883/the-inflammatory-state-provokes-sexual-dimorphism-in-left-ventricular-and-electrocardiographic-effects-of-chronic-cyclosporine-in-rats
#5
Hany M El-Bassossy, Zainy M Banjar, Mahmoud M El-Mas
Although cardiotoxicity has been recognized as an adverse effect of cyclosporine A (CSA), no information exists regarding sex specificity of CSA cardiotoxicity. We tested the hypothesis that left ventricular (LV) and electrocardiographic (ECG) effects of CSA and related inflammatory/histopathological derangements are sex related. CSA reduced the LV slope of end-systolic pressure volume relationship and increased isovolumic relaxation constant. These effects were more pronounced in male compared to female rats, suggesting LV systolic and diastolic dysfunction...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28209348/effects-of-metabolically-healthy-and-unhealthy-obesity-on-prolongation-of-corrected-qt-interval
#6
Xiaofan Guo, Zhao Li, Liang Guo, Shasha Yu, Hongmei Yang, Liqiang Zheng, Guowei Pan, Yonghong Zhang, Yingxian Sun, Mark J Pletcher
Although obesity and the metabolic syndrome (MS) often co-occur, many obese (OB) subjects have a favorable metabolic profile. It is unclear whether these factors independently influence cardiac electrophysiology including prolongation of the QT interval. We examined associations among obesity, MS, and prolonged corrected QT (QTc) interval in a large sample of Chinese research participants aged ≥35 years recruited from rural areas of Liaoning Province during 2012 to 2013. Of the 11,209 participants, 6,364 (56...
January 25, 2017: American Journal of Cardiology
https://www.readbyqxmd.com/read/28205376/drug-drug-interactions-in-pediatric-oncology-patients
#7
T E Balk, I H van der Sijs, T van Gelder, J J B Janssen, I M van der Sluis, R W F van Leeuwen, F K Engels
BACKGROUND: Drug-drug interactions (DDIs) can negatively affect pharmacotherapy. However, pediatric DDI studies are scarce. We undertook an exploratory study to investigate prevalence and clinical relevance of DDIs between cytostatic and noncytostatic drugs in outpatient pediatric oncology patients. PROCEDURE: After informed consent and inclusion, the following information was collected: currently prescribed noncytostatic and cytostatic drugs, comorbidities, and use of over-the-counter (OTC) drugs, complementary and alternative medicines (CAMs), and dietary supplements...
February 16, 2017: Pediatric Blood & Cancer
https://www.readbyqxmd.com/read/28198590/effect-of-therapeutic-and-supratherapeutic-doses-of-vonoprazan-on-the-qt-qtc-interval-in-a-phase-i-randomized-study-in-healthy-subjects
#8
B Astruc, H Jenkins, R Jenkins
This phase I, randomized, 4-period, 4-sequence, double-blind, active- and placebo-controlled, crossover study assessed the effects of vonoprazan on the QT/QTc interval in healthy subjects. Subjects received single oral doses of vonoprazan 40 mg, vonoprazan 120 mg, moxifloxacin 400 mg (positive control/open label), and placebo. The primary end point was time-matched, placebo-corrected, baseline-adjusted mean Fridericia-corrected QT interval (ddQTcF). Of 64 subjects (mean age, 37.8 years; 50% male), 63 received all four regimens...
February 15, 2017: Clinical and Translational Science
https://www.readbyqxmd.com/read/28186837/methadone-and-corrected-qt-prolongation-in-pain-and-palliative-care-patients-a-case-control-study
#9
Katherine M Juba, Tina M Khadem, David J Hutchinson, Jack E Brown
BACKGROUND: Methadone (ME) is commonly used in pain and palliative care (PPC) patients with refractory pain or intolerable opioid adverse effects (AEs). A unique ME AE is its corrected QT (QTc) interval prolongation risk, but most evidence exists in methadone maintenance therapy patients. OBJECTIVE: Our goal was to identify QTc interval prolongation risk factors in PPC patients receiving ME and other medications known to prolong the QTc interval and develop a risk stratification tool...
February 10, 2017: Journal of Palliative Medicine
https://www.readbyqxmd.com/read/28182551/fetal-qt-interval-estimation-using-sequential-hypothesis-testing
#10
Suhong Yu, Barry VanVeen, William Lutter, Ronald Wakai
OBJECTIVE: Recent studies utilizing fetal magnetocardiography have demonstrated the efficacy of corrected QT interval (QTc) measurement for in utero diagnosis and prognosis of long QT syndrome, a leading cause of sudden death in early life. The objective of the study was to formulate and test a novel statistical estimation method to detect the end of the fetal T-wave and thereby improve the accuracy of fetal QT interval measurement. METHODS: To detect the end of the T-wave we apply a sequential composite hypothesis test to decide when the T-wave has returned to baseline...
February 2, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28178705/sudden-cardiac-arrest-triggered-by-coadministration-of-fluconazole-and-amiodarone
#11
Jiajia Wang, Yanbin Chen, Wei Lei, Cheng Chen, Yehan Zhu, Nan Su, Chuankai Zhang, Jian-An Huang
Fluconazole for fungal infections and amiodarone for arrhythmia are commonly prescribed medications, and coadministration of such medications is sometimes inevitable in clinical practice. However, both medications have been associated with prolonged QTc intervals and subsequent arrhythmias, which are sometimes fatal. We present the case of a 75-year-old man with sudden cardiac arrest triggered by coadministration of fluconazole and amiodarone, which raises the need for caution regarding coadministration of these medications...
February 9, 2017: Cardiology
https://www.readbyqxmd.com/read/28178614/geraniol-alleviates-diabetic-cardiac-complications-effect-on-cardiac-ischemia-and-oxidative-stress
#12
Hany M El-Bassossy, Hanna Ghaleb, Ahmed A Elberry, Khadijah S Balamash, Salah A Ghareib, Ahmad Azhar, Zainy Banjar
The present study was planned to assess the possible protective effect of geraniol on cardiovascular complications in an animal model with diabetes. Diabetes was induced in rats by a single streptozotocin injection. In the treated group, geraniol (150mgkg(-1)day(-1)) was administered orally starting from the 15th day after induction of diabetes, and ending after 7 weeks; diabetic control rats were given vehicle for the same period. At the end of the study, cardiac contractility was assessed by using a Millar microtip catheter in anesthetised rats, and cardiac conductivity determined by a surface ECG...
February 5, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28177919/camkii-inhibition-reduces-isoproterenol-induced-ischemia-and-arrhythmias-in-hypertrophic-mice
#13
Ying Feng, Jun Cheng, Baozhu Wei, Yanggan Wang
OBJECTIVES: The Ca/calmodulin-dependent protein kinase II (CaMKII), an arrhythmogenic molecule, is excessively activated in cardiac hypertrophy. Here, we investigated the effect of CaMKII inhibition in isoproterenol (ISO)-induced arrhythmias in hypertrophic mice. RESULTS: ISO induced multiple types of arrhythmias in the hypertrophic mice but not in the normal mice. The QTc intervals were prolonged and the amplitudes of T waves were increased significantly by ISO prior to arrhythmia initiation...
February 4, 2017: Oncotarget
https://www.readbyqxmd.com/read/28164349/applicability-of-a-novel-formula-bogossian-formula-for-evaluation-of-the-qt-interval-in-heart-failure-and-left-bundle-branch-block-due-to-right-ventricular-pacing
#14
Gerrit Frommeyer, Harilaos Bogossian, Eleni Pechlivanidou, Philipp Conzen, Christopher Gemein, Kay Weipert, Inga Helmig, Ritvan Chasan, Victoria Johnson, Lars Eckardt, Christian W Hamm, Melchior Seyfarth, Bernd Lemke, Markus Zarse, Jörn Schmitt, Damir Erkapic
BACKGROUND: The presence of left bundle branch block (LBBB) due to right ventricular pacing represents a particular challenge in properly measuring the QTc interval. In 2014 a new formula for evaluation of QT interval in patients with LBBB was reported. METHODS: 145 patients with implantable cardioverter defibrillator (ICD) were included in this prospective multicenter observational study. Inclusion criteria were: no permanent right ventricular stimulation, an intrinsic QRS interval of <120ms and reduced left ventricular function...
February 5, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28163537/qtc-interval-in-young-gujarati-hypertensives-effect-of-disease-antihypertensive-monotherapy-and-coexisting-risk-factors
#15
Jayesh Dalpatbhai Solanki, Bhakti P Gadhavi, Amit H Makwana, Hemant B Mehta, Chinmay J Shah, Pradnya A Gokhale
OBJECTIVES: To study the effect of disease duration, treatment and risk factors on QTc interval among young hypertensives. MATERIALS AND METHODS: A case-control study was conducted on 142 hypertensives (60 males, 82 females) taking calcium channel blocker (CCB) or angiotensin-converting enzyme inhibitor (ACEI) as monotherapy. After blood pressure measurement, we recorded lead II electrocardiograph with minimum ten waveforms. QTc was derived from average of ten values using Bazett's formula...
October 2016: Journal of Pharmacology & Pharmacotherapeutics
https://www.readbyqxmd.com/read/28155223/evaluation-of-prolonged-qt-interval-structural-heart-disease-mimicking-long-qt-syndrome
#16
Adaya Weissler-Snir, Michael H Gollob, Vijay Chauhan, Melanie Care, Danna A Spears
BACKGROUND: In about 20-25% of patients with congenital long QT syndrome (LQTS) a causative pathogenic mutation is not found. The aim of this study was to explore the prevalence of alternative cardiac diagnoses among patients exhibiting prolongation of QT interval with negative genetic testing for LQTS genes. METHODS: We conducted a retrospective analysis of 239 consecutive patients who were evaluated in the inherited arrhythmia clinic at the Toronto General Hospital between July 2013 and December 2015 for possible LQTS...
February 3, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28154763/qt-prolongation-due-to-graves-disease
#17
Zain Kulairi, Nisha Deol, Renee Tolly, Rohan Manocha, Maliha Naseer
Hyperthyroidism is a highly prevalent disease affecting over 4 million people in the US. The disease is associated with many cardiac complications including atrial fibrillation and also less commonly with ventricular tachycardia and fibrillation. Many cardiac pathologies have been extensively studied; however, the relationship between hyperthyroidism and rate of ventricular repolarization manifesting as a prolonged QTc interval is not well known. Prolonged QTc interval regardless of thyroid status is a risk factor for cardiovascular mortality and life-threatening ventricular arrhythmia...
2017: Case Reports in Cardiology
https://www.readbyqxmd.com/read/28149075/epileptic-patients-are-at-risk-of-cardiac-arrhythmias-a-novel-approach-using-qt-nomogram-tachogram-and-cardiac-restitution-plots
#18
Marwan S Al-Nimer, Sura A Al-Mahdawi, Namir M Abdullah, Akram Al-Mahdawi
BACKGROUND: Sudden death is reported in patients who had a history of epilepsy and some authors believed that is due to cardiac arrhythmias. OBJECTIVES: This study aimed to predict that the epileptic patients are at risk of serious cardiac arrhythmias by QT-nomogram, tachogram (Lorenz), and cardiac restitution plots. METHODS: A total number of 71 healthy subjects (Group I) and 64 newly diagnosed epileptic patients (Group II) were recruited from Al-Yarmouk and Baghdad Teaching hospitals in Baghdad from March 2015 to July 2015 and included in this study...
January 2017: Journal of Neurosciences in Rural Practice
https://www.readbyqxmd.com/read/28137484/lung-function-percent-emphysema-and-qt-duration-the-multi-ethnic-study-of-atherosclerosis-mesa-lung-study
#19
Hilary F Armstrong, Gina S Lovasi, Elsayed Z Soliman, Susan R Heckbert, Bruce M Psaty, John H M Austin, Jerry A Krishnan, Eric A Hoffman, Craig Johnson, Matthew J Budoff, Karol E Watson, R Graham Barr
BACKGROUND: The QT interval on electrocardiogram (ECG) reflects ventricular repolarization; a prolonged QT interval is associated with increased mortality risk. Prior studies suggest an association between chronic obstructive pulmonary disease (COPD) and prolonged QT interval. However, these studies were small and often enrolled hospital-based samples. We tested the hypotheses that lower lung function and increased percent emphysema on computed tomography (CT) are associated with a prolonged QT interval in a general population sample and additionally in those with COPD...
February 2017: Respiratory Medicine
https://www.readbyqxmd.com/read/28129701/how-gender-affects-the-pharmacotherapeutic-approach-to-treating-psychosis-a-systematic-review
#20
Bettina Lange, Juliane Katrina Mueller, F Markus Leweke, Jan Malte Bumb
The effectiveness, effective dosages and side effect profiles of antipsychotic medication differ significantly between the sexes. Areas covered: We present a systematic review of gender-differences in the treatment of psychosis focusing on randomized, controlled trials and meta-analyses. Expert opinion: Despite many years of research, the database on gender-differences affecting the pharmacotherapeutic approach to treating psychosis is insufficient. Currently, the US National Institute of Health encouraged the enrolment of female participants in federally supported phase III clinical trials to increase the data available of female patients...
January 27, 2017: Expert Opinion on Pharmacotherapy
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