1
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Wisedchaisri G, Gamal El-Din TM, Powell NM, Zheng N, Catterall WA. Structural basis for severe pain caused by mutations in the voltage sensors of sodium channel NaV1.7. J Gen Physiol 2023; 155:e202313450. [PMID: 37903281 PMCID: PMC10616507 DOI: 10.1085/jgp.202313450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/11/2023] [Accepted: 10/10/2023] [Indexed: 11/01/2023] Open
Abstract
Voltage-gated sodium channels in peripheral nerves conduct nociceptive signals from nerve endings to the spinal cord. Mutations in voltage-gated sodium channel NaV1.7 are responsible for a number of severe inherited pain syndromes, including inherited erythromelalgia (IEM). Here, we describe the negative shifts in the voltage dependence of activation in the bacterial sodium channel NaVAb as a result of the incorporation of four different IEM mutations in the voltage sensor, which recapitulate the gain-of-function effects observed with these mutations in human NaV1.7. Crystal structures of NaVAb with these IEM mutations revealed that a mutation in the S1 segment of the voltage sensor facilitated the outward movement of S4 gating charges by widening the pathway for gating charge translocation. In contrast, mutations in the S4 segments modified hydrophobic interactions with surrounding amino acid side chains or membrane phospholipids that would enhance the outward movement of the gating charges. These results provide key structural insights into the mechanisms by which these IEM mutations in the voltage sensors can facilitate outward movements of the gating charges in the S4 segment and cause hyperexcitability and severe pain in IEM. Our work gives new insights into IEM pathogenesis at the near-atomic level and provides a molecular model for mutation-specific therapy of this debilitating disease.
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Affiliation(s)
| | | | - Natasha M. Powell
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
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2
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Henein MY, Vancheri S, Longo G, Vancheri F. The Impact of Mental Stress on Cardiovascular Health—Part II. J Clin Med 2022; 11:jcm11154405. [PMID: 35956022 PMCID: PMC9369438 DOI: 10.3390/jcm11154405] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/23/2022] [Accepted: 07/26/2022] [Indexed: 12/03/2022] Open
Abstract
Endothelial dysfunction is one of the earliest manifestations of atherosclerosis, contributing to its development and progression. Mental stress induces endothelial dysfunction through increased activity of the sympathetic nervous system, release of corticotropin-releasing hormone from the hypothalamus, inhibition of nitric oxide (NO) synthesis by cortisol, and increased levels of pro-inflammatory cytokines. Mental-stress-induced increased output of the sympathetic nervous system and concomitant withdrawal of the parasympathetic inflammatory reflex results in systemic inflammation and activation of a neural–hematopoietic–arterial axis. This includes the brainstem and subcortical regions network, bone marrow activation, release of leukocytes into the circulation and their migration to the arterial wall and atherosclerotic plaques. Low-grade, sterile inflammation is involved in all steps of atherogenesis, from coronary plaque formation to destabilisation and rupture. Increased sympathetic tone may cause arterial smooth-muscle-cell proliferation, resulting in vascular hypertrophy, thus contributing to the development of hypertension. Emotional events also cause instability of cardiac repolarisation due to brain lateralised imbalance of cardiac autonomic nervous stimulation, which may lead to asymmetric repolarisation and arrhythmia. Acute emotional stress can also provoke severe catecholamine release, leading to direct myocyte injury due to calcium overload, known as myocytolysis, coronary microvascular vasoconstriction, and an increase in left ventricular afterload. These changes can trigger a heart failure syndrome mimicking acute myocardial infarction, characterised by transient left ventricular dysfunction and apical ballooning, known as stress (Takotsubo) cardiomyopathy. Women are more prone than men to develop mental-stress-induced myocardial ischemia (MSIMI), probably reflecting gender differences in brain activation patterns during mental stress. Although guidelines on CV prevention recognise psychosocial factors as risk modifiers to improve risk prediction and decision making, the evidence that their assessment and treatment will prevent CAD needs further evaluation.
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Affiliation(s)
- Michael Y. Henein
- Institute of Public Health and Clinical Medicine, Umea University, 90187 Umea, Sweden;
- Brunel University, Middlesex, London UB8 3PH, UK
- St. George’s University, London SW17 0RE, UK
| | - Sergio Vancheri
- Radiology Department, I.R.C.C.S. Policlinico San Matteo, 27100 Pavia, Italy;
| | - Giovanni Longo
- Cardiovascular and Interventional Department, S. Elia Hospital, 93100 Caltanissetta, Italy;
| | - Federico Vancheri
- Department of Internal Medicine, S. Elia Hospital, 93100 Caltanissetta, Italy
- Correspondence:
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3
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Etienne P, Huchet F, Gaborit N, Barc J, Thollet A, Kyndt F, Guyomarch B, Le Marec H, Charpentier F, Schott JJ, Redon R, Probst V, Gourraud JB. Mental stress test: a rapid, simple, and efficient test to unmask long QT syndrome. Europace 2018; 20:2014-2020. [DOI: 10.1093/europace/euy078] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 03/20/2018] [Indexed: 11/14/2022] Open
Affiliation(s)
- Pauline Etienne
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - François Huchet
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | | | - Julien Barc
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, Nantes, France
| | - Aurélie Thollet
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - Florence Kyndt
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - Béatrice Guyomarch
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - Hervé Le Marec
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - Flavien Charpentier
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - Jean-Jacques Schott
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - Richard Redon
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - Vincent Probst
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
| | - Jean-Baptiste Gourraud
- l’institut du thorax, INSERM, CNRS, UNIV Nantes, CHU de Nantes, Boulevard Jacques Monod, Nantes, France
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4
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Määttänen I, Ravaja N, Henttonen P, Puttonen S, Paavonen K, Swan H, Hintsa T. Type 1 long QT syndrome and psychological stress in a laboratory setting. J Health Psychol 2018; 25:1213-1221. [PMID: 29355047 DOI: 10.1177/1359105317751617] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Trait-like sensitivity to stress in long QT syndrome patients has been documented previously. In addition, mental stress has been associated with symptomatic status of long QT syndrome. We examined whether the symptomatic type 1 long QT syndrome patients would be more sensitive to mental stress compared to asymptomatic patients and whether there would be differences in task-related physiological stress reactions between type 1 long QT syndrome patients and healthy individuals. The study population consisted of 21 symptomatic and 23 asymptomatic molecularly defined KCNQ1 mutation carriers, their 32 non-carrier relatives and 46 non-related healthy controls, with mean ages of 37, 39, 35 and 23 years, respectively. Electrocardiography was utilised to calculate inter-beat interval and high frequency and low frequency heart rate variability. Blood pressure was measured and mean arterial pressure and pulse pressure were calculated. Stress was induced using three different tasks: mental arithmetic, reaction time and public speech. Stress responses of symptomatic and asymptomatic type 1 long QT syndrome patients were not statistically different in any of the stress tasks. Short-term physiological stress reactivity of symptomatic type 1 long QT syndrome patients appears to be normal and does not enhance the risk assessment of asymptomatic mutation carriers.
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Affiliation(s)
| | | | | | - Sampsa Puttonen
- University of Helsinki, Finland.,Finnish Institute of Occupational Health, Finland
| | - Kristian Paavonen
- University of Helsinki, Finland.,Helsinki University Hospital Heart and Lung Center, Finland
| | - Heikki Swan
- University of Helsinki, Finland.,Helsinki University Hospital Heart and Lung Center, Finland
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5
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Huchet F, Kyndt F, Barc J, Thollet A, Charpentier F, Redon R, Schott JJ, le Marec H, Probst V, Gourraud JB. Familial Catecholamine-Induced QT Prolongation in Unexplained Sudden Cardiac Death. J Am Coll Cardiol 2017; 69:1642-1643. [DOI: 10.1016/j.jacc.2017.01.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/10/2017] [Accepted: 01/18/2017] [Indexed: 10/19/2022]
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6
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Takahashi K, Nabeshima T, Nakayashiro M, Ganaha H. QT Dynamics During Exercise in Asymptomatic Children with Long QT Syndrome Type 3. Pediatr Cardiol 2016; 37:860-7. [PMID: 26921063 DOI: 10.1007/s00246-016-1360-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/13/2016] [Indexed: 01/08/2023]
Abstract
Sympathetic provocative testing is commonly used to detect the abnormal QT dynamics in long QT syndrome (LQTS) patients, particularly LQTS type 1 and type 2. However, little is known about LQTS type 3 (LQT3). We investigated QT dynamics during exercise testing in LQTS patients, particularly LQT3. This study included 37 subjects, comprising 16 genotyped LQTS patients and 21 unrelated healthy subjects without QT prolongation. LQTS patients were divided into LQT3 and non-LQT3 groups. During exercise tests using a modified Bruce protocol, 12-lead electrocardiogram monitoring was performed using a novel multifunctional electrocardiograph. QT intervals were automatically measured. The QT/heart rate (HR) relationship was visualized by plotting the beat-to-beat confluence of the recorded data. A linear regression analysis was performed to determine the QT/HR slope and intercept. Estimated QT intervals at HR 60 bpm (QT60) were calculated by the regression line formula. QT/HR slopes were steeper for each LQTS group than for the control group (P < 0.001). QT60 values demonstrated a moderate correlation with QT intervals at rest (P < 0.0001) for both groups. The corrected QT intervals (QTc) at 4 min of recovery after exercise were significantly longer in the non-LQT3 group than in the control group but were not different between the LQT3 and the control groups. Abnormal QT dynamics during exercise testing were observed in both LQT3 patients and other LQTS subtypes. This method may be useful for directing genetic testing in subjects with borderline prolonged QT intervals.
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Affiliation(s)
- Kazuhiro Takahashi
- Department of Pediatric Cardiology, Okinawa Children's Medical Center, 118-1 Arakawa, Haebaru-chou, Okinawa, 901-1193, Japan.
| | - Taisuke Nabeshima
- Department of Pediatric Cardiology, Okinawa Children's Medical Center, 118-1 Arakawa, Haebaru-chou, Okinawa, 901-1193, Japan
| | - Mami Nakayashiro
- Department of Pediatric Cardiology, Okinawa Children's Medical Center, 118-1 Arakawa, Haebaru-chou, Okinawa, 901-1193, Japan
| | - Hitoshi Ganaha
- Department of Pediatric Cardiology, Okinawa Children's Medical Center, 118-1 Arakawa, Haebaru-chou, Okinawa, 901-1193, Japan
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7
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Zaydman MA, Kasimova MA, McFarland K, Beller Z, Hou P, Kinser HE, Liang H, Zhang G, Shi J, Tarek M, Cui J. Domain-domain interactions determine the gating, permeation, pharmacology, and subunit modulation of the IKs ion channel. eLife 2014; 3:e03606. [PMID: 25535795 PMCID: PMC4381907 DOI: 10.7554/elife.03606] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 11/19/2014] [Indexed: 01/22/2023] Open
Abstract
Voltage-gated ion channels generate electrical currents that control muscle
contraction, encode neuronal information, and trigger hormonal release.
Tissue-specific expression of accessory (β) subunits causes these channels to
generate currents with distinct properties. In the heart, KCNQ1 voltage-gated
potassium channels coassemble with KCNE1 β-subunits to generate the
IKs current (Barhanin et al.,
1996; Sanguinetti et al., 1996),
an important current for maintenance of stable heart rhythms. KCNE1 significantly
modulates the gating, permeation, and pharmacology of KCNQ1 (Wrobel et al., 2012; Sun et
al., 2012; Abbott, 2014). These
changes are essential for the physiological role of IKs (Silva and Rudy, 2005); however, after 18 years
of study, no coherent mechanism explaining how KCNE1 affects KCNQ1 has emerged. Here
we provide evidence of such a mechanism, whereby, KCNE1 alters the state-dependent
interactions that functionally couple the voltage-sensing domains (VSDs) to the
pore. DOI:http://dx.doi.org/10.7554/eLife.03606.001 Cells are surrounded by a membrane that prevents charged molecules from flowing
directly into or out of the cell. Instead ions move through channel proteins within
the cell membrane. Most ion channel proteins are selective and only allow one or a
few types of ion to cross. Ion channels can also be ‘gated’, and have a
central pore that can open or close to allow or stop the flow of selected ions. This
gating can be affected by the channel sensing changes in conditions, such as changes
in the voltage across the cell membrane. Research conducted more than half a century ago—before the discovery of
channel proteins—led to a mathematical model of the flow of potassium ions
across a membrane in response to changes in voltage. This model made a number of
assumptions, many of which are still widely accepted. However, Zaydman et al. have
now called into question some of the assumptions of this model. Based on the original model, it has been long assumed that the voltage-sensing
domains that open or close the central pore in response to changes in voltage must be
fully activated to allow the channel to open. It had also been assumed that the
voltage-sensing domains do not affect the flow of ions once the channel is open.
Zaydman et al. have now shown that these assumptions are not valid for a specific
voltage-gated potassium channel called KCNQ1. Instead, this ion channel opens when
its voltage-sensing domains are either partially or fully activated. Zaydman found
that the intermediate-open and activated-open states had different preferences for
passing various types of ion; therefore, the gating of the channel and the flow of
ions through the open channel are both dependent on the state of the voltage-sensing
domains. This is in direct contrast to what had previously been assumed. The original model cannot reproduce the gating of KCNQ1, nor can any other
established model. Therefore, Zaydman et al. devised a new model to understand how
the interactions between different states of the voltage-sensing domains and the pore
lead to gating. Zaydman et al. then used their model to address how another protein
called KCNE1 is able to alter properties of the KCNQ1 channel. KCNE1 is a protein that is expressed in the heart muscle cell and mutations affecting
KCNQ1 or KCNE1 have been associated with potentially fatal heart conditions. Based on
the assumptions of the original model, it had been difficult to understand how KCNE1
was able to affect different properties of the KCNQ1 channel. Thus, for nearly 20
years it has been debated whether KCNE1 primarily affects the activation of the
voltage-sensing domains or the opening of the pore. Zaydman et al. found instead that
KCNE1 alters the interactions between the voltage-sensing domains and the pore, which
prevented the intermediate-open state and modified the properties of the
activated-open state. This mechanism provides one of the most complete explanations
for the action of the KCNE1 protein. DOI:http://dx.doi.org/10.7554/eLife.03606.002
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Affiliation(s)
- Mark A Zaydman
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Marina A Kasimova
- Theory, Modeling, and Simulations, UMR 7565, Université de Lorraine, Nancy, France
| | - Kelli McFarland
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Zachary Beller
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Panpan Hou
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Holly E Kinser
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Hongwu Liang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Guohui Zhang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Mounir Tarek
- Theory, Modeling, and Simulations, UMR 7565, Université de Lorraine, Nancy, France
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
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8
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Määttänen I, Jokela M, Pulkki-Råback L, Keltikangas-Järvinen L, Swan H, Toivonen L, Merjonen P, Hintsa T. Brief report: Emotional distress and recent stressful life events in long QT syndrome mutation carriers. J Health Psychol 2013; 20:1445-50. [PMID: 24335348 DOI: 10.1177/1359105313513049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
To study emotional distress in symptomatic and asymptomatic long QT syndrome mutation carriers who had experienced a recent stressful life event. The participants were 209 symptomatic and 279 asymptomatic long QT syndrome mutation carriers. Emotional distress was assessed with the Cope questionnaire and stressful life events with the Social Readjustment Rating Scale. Symptomatic long QT syndrome mutation carriers with burdening recent stressful life events reported a higher emotional distress (β = 0.35, p < 0.001), while the asymptomatic did not show such difference (β = 0.13, p = 0.393). Symptomatic long QT syndrome mutation carriers who have experienced stressful life events recently report an increased emotional distress.
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9
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Määttänen I, Keltikangas-Järvinen L, Swan H, Toivonen L, Kontula K, Hintsanen M, Alatupa S, Hintsa T. Stress proneness in molecularly defined long QT syndrome: a study using temperament assessment by behavioural inhibition system scale. Stress Health 2013; 29:150-5. [PMID: 22936642 DOI: 10.1002/smi.2441] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 07/04/2012] [Accepted: 07/05/2012] [Indexed: 11/10/2022]
Abstract
The long QT syndrome (LQTS) is an inherited cardiac disorder that predisposes the mutation carrier to ventricular arrhythmias that can lead to sudden death. The objective of the present study was to replicate the previous finding in terms of stress-related temperament trait, i.e. behavioural inhibition system (BIS). The study subjects included 583 LQTS mutation carriers (256 symptomatic and 327 asymptomatic) from the Finnish LQTS registry and 79 healthy subjects randomly derived from the population-based sample of the Young Finns Study. Symptomatic and asymptomatic LQTS mutation carriers did not differ from each other on BIS (3.27 versus 3.24, p > 0.05), whereas LQTS mutation carriers scored higher on BIS than the comparison group derived from the representative population-based sample (3.25 versus 2.99, p = 0.003, η² = 0.014). BIS was significantly higher in women than in men (3.32 versus 3.06, p < 0.001, η² = 0.017). The results confirm our previous finding of higher stress proneness of LQTS mutation carriers. Their innate stress proneness may have relevance because it increases our understanding on the role of stress in the manifestation of symptoms.
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Affiliation(s)
- Ilmari Määttänen
- IBS, Unit of Personality, Work and Health Psychology, University of Helsinki, Helsinki, Finland
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10
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Krahn AD, Healey JS, Chauhan VS, Birnie DH, Champagne J, Sanatani S, Ahmad K, Ballantyne E, Gerull B, Yee R, Skanes AC, Gula LJ, Leong-Sit P, Klein GJ, Gollob MH, Simpson CS, Talajic M, Gardner M. Epinephrine Infusion in the Evaluation of Unexplained Cardiac Arrest and Familial Sudden Death. Circ Arrhythm Electrophysiol 2012; 5:933-40. [DOI: 10.1161/circep.112.973230] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Epinephrine infusion may unmask latent genetic conditions associated with cardiac arrest, including long-QT syndrome and catecholaminergic polymorphic ventricular tachycardia (VT).
Methods and Results—
Patients with unexplained cardiac arrest (normal left ventricular function and QT interval) and selected family members from the Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) registry underwent epinephrine challenge at doses of 0.05, 0.10, and 0.20 μg/kg per minute. A test was considered positive for long-QT syndrome if the absolute QT interval prolonged by ≥30 ms at 0.10 μg/kg per minute and borderline if QT prolongation was 1 to 29 ms. Catecholaminergic polymorphic VT was diagnosed if epinephrine provoked ≥3 beats of polymorphic or bidirectional VT and borderline if polymorphic couplets, premature ventricular contractions, or nonsustained monomorphic VT was induced. Epinephrine infusion was performed in 170 patients (age, 42±16 years; 49% men), including 98 patients with unexplained cardiac arrest. Testing was positive for long-QT syndrome in 31 patients (18%) and borderline in 24 patients (14%). Exercise testing provoked an abnormal QT response in 42% of tested patients with a positive epinephrine response. Testing for catecholaminergic polymorphic VT was positive in 7% and borderline in 5%. Targeted genetic testing of abnormal patients was positive in 17% of long-QT syndrome patients and 13% of catecholaminergic polymorphic VT patients.
Conclusions—
Epinephrine challenge provoked abnormalities in a substantial proportion of patients, most commonly a prolonged QT interval. Exercise and genetic testing replicated the diagnosis suggested by the epinephrine response in a small proportion of patients. Epinephrine infusion combined with exercise testing and targeted genetic testing is recommended in the workup of suspected familial sudden death syndromes.
Clinical Trial Registration—
URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT00292032.
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Affiliation(s)
- Andrew D. Krahn
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Jeffrey S. Healey
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Vijay S. Chauhan
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - David H. Birnie
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Jean Champagne
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Shubhayan Sanatani
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Kamran Ahmad
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Emily Ballantyne
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Brenda Gerull
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Raymond Yee
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Allan C. Skanes
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Lorne J. Gula
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Peter Leong-Sit
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - George J. Klein
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Michael H. Gollob
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Christopher S. Simpson
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Mario Talajic
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Martin Gardner
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
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11
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Horner JM, Horner MM, Ackerman MJ. The diagnostic utility of recovery phase QTc during treadmill exercise stress testing in the evaluation of long QT syndrome. Heart Rhythm 2011; 8:1698-704. [DOI: 10.1016/j.hrthm.2011.05.018] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 05/21/2011] [Indexed: 10/18/2022]
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12
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Määttänen I, Hintsa T, Toivonen L, Swan H, Pulkki-Råback L, Hintsanen M, Kontula K, Keltikangas-Järvinen L. Cloninger's temperament traits and inherited long QT syndrome. J Psychosom Res 2011; 71:245-9. [PMID: 21911102 DOI: 10.1016/j.jpsychores.2011.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 03/10/2011] [Accepted: 03/29/2011] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The long QT syndrome (LQTS) is an inherited cardiac disorder which predisposes the mutation carrier to ventricular arrhythmias that can lead to sudden death. The objective of the present study was to examine the association between the symptom status of congenital long QT syndrome mutation carriers and their temperament. METHODS The study subjects included 587 LQTS mutation carriers from the Finnish LQTS registry, and 2056 individuals from a database study, the Young Finns Study (YFS), representing general population and serving as control subjects. The LQTS subjects were divided into symptomatic (n=259) and asymptomatic (n=328) groups, according to their history of arrhythmic events. Temperament was assessed using the Cloninger's Temperament and Character Inventory (TCI), assessing novelty seeking, harm avoidance and reward dependence. RESULTS Congenital long QT syndrome mutation carriers had a higher harm avoidance (HA) than those representing the general population (2.77 vs. 2.61, p<.001, η²=0.011). Symptomatic and asymptomatic LQTS mutation carriers did not differ from one another in any of the three Cloninger's temperament traits. HA was significantly higher in women (2.72 vs. 2.54, p<0.001 η²=0.017). CONCLUSIONS LQTS mutation carriers may have higher stress proneness because of their high HA, which in turn may predispose them to the effects of environmental loading and thus increase the risk of arrhythmias.
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Affiliation(s)
- Ilmari Määttänen
- Institute of Behavioral Sciences, Psychology, University of Helsinki, Helsinki, Finland
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13
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Air medical providers' physiological response to a simulated trauma scenario. Air Med J 2011; 30:86-90, 92. [PMID: 21382567 DOI: 10.1016/j.amj.2010.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 10/21/2010] [Accepted: 11/03/2010] [Indexed: 11/22/2022]
Abstract
INTRODUCTION We assessed heart rate as a surrogate measure of psychological response to determine whether high-fidelity simulation reproduces a stressful atmosphere for air medical providers. METHODS A prospective simulation study of air-medical providers at a level 1 trauma center randomized to adult or pediatric trauma scenarios in an ambulance. Continuous closed circuit video and wireless heart rate monitoring was conducted from the time of initial patient simulator contact to completion of packaging for transport. RESULTS The 19 air-medical providers had the following characteristics: younger than 40 years of age 90%; male 63%; registered nurses (RN) 37%, emergency medical technician-paramedics (EMT-P) 53%; mean time in practice 9 years; mean resting heart rate 71 beats per minute (bpm). Heart rate increased during study intake through start of the scenario, plateaued, and then increased abruptly on scenario completion. "Anticipatory" heart rate (during study intake) and peak heart rate were higher in less versus more experienced providers 106 bpm versus 92 bpm and 132 versus 123 bpm. CONCLUSION Providers demonstrated increased heart rates when exposed to high-fidelity simulation of critically injured trauma patients. Future studies should determine whether simulation continues to provoke this physiological response, and whether this response occurs during live operations.
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14
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Abstract
Prolonged QT interval is associated with the generation of life-threatening arrhythmias and sudden death. However, neither the relation between QT duration and heart rate, nor the association between mental stress and QT time has been clarified. Aim: The relationship between QT duration and smoking, cardiovascular reactivity, and mental stress as well as newer methods of QT correction were studied. Methods: In six laboratory experiments 166 volunteers were studied. Smoking, treadmill exercise, mental arithmetic and videogame were applied as stressors. Besides fixed formulae, study and subject-specific QT correction methods were also used. Results: 1. Bazett formula is not appropriate to compare QT durations. 2. Acute smoking has no effect on QT time. 3. QT changes are related to cardiovascular reactivity. 4. Mental stress may induce QT prolongation. 5. Bifid T waves often develop during mental and isometric stress. Conclusions: New methods for QT correction are more reliable than preformed formulae. QT prolongation and bifid T waves may be the links between mental stress and life threatening arrhythmias.
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Affiliation(s)
- Gábor Andrássy
- Budapesti Szent Ferenc Kórház Budapest Széher u. 73. 1021
- Semmelweis Egyetem Elméleti Orvostudományok Doktori Iskola Budapest
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15
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Hintsa T, Keltikangas-Järvinen L, Puttonen S, Ravaja N, Toivonen L, Kontula K, Swan H. Depressive symptoms in the congenital long QT syndrome. Ann Med 2009; 41:516-21. [PMID: 19551538 DOI: 10.1080/07853890903037254] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND A proportion of patients with congenital long QT syndrome (LQTS) experience potentially life-threatening cardiac arrhythmias. AIM To examine whether depressive symptoms are related to arrhythmic events among symptomatic and asymptomatic LQTS patients, and syncope events among their relatives not carrying the family's LQTS-causing mutation. METHODS The participants were 569 molecularly defined LQTS mutation carriers and 622 non-carrier relatives from the Finnish LQTS registry. Depressive symptoms were self-rated with a revised version of the Beck Depression Inventory. RESULTS LQTS patients with arrhythmic events scored higher on depressive symptoms than those without (P=0.011) or the control group (P=0.005). In addition, in the binary logistic regression analysis including symptomatic and asymptomatic LQTS mutation carriers, depressive symptoms showed an age- and sex-adjusted association of odds ratio (OR) 1.40 (95% confidence interval (CI) 1.12-1.74) with symptomatic status of LQTS. In similar analysis including non-carriers of the LQTS mutation, there was no association between depressive symptoms and history of syncope events OR 1.23 (95% CI 0.99-1.53). CONCLUSION Our results from this relatively large genotyped LQTS patient cohort indicate that depressive symptoms are associated with arrhythmic events in LQTS patients. Whether depressive symptoms are causally related to arrhythmias in LQTS remains uncertain.
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Affiliation(s)
- Taina Hintsa
- Department of Psychology, University of Helsinki, FIN-00014, Helsinki, Finland.
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16
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Seebohm G, Strutz-Seebohm N, Ureche ON, Henrion U, Baltaev R, Mack AF, Korniychuk G, Steinke K, Tapken D, Pfeufer A, Kääb S, Bucci C, Attali B, Merot J, Tavare JM, Hoppe UC, Sanguinetti MC, Lang F. Long QT syndrome-associated mutations in KCNQ1 and KCNE1 subunits disrupt normal endosomal recycling of IKs channels. Circ Res 2008; 103:1451-7. [PMID: 19008479 DOI: 10.1161/circresaha.108.177360] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Physical and emotional stress is accompanied by release of stress hormones such as the glucocorticoid cortisol. This hormone upregulates the serum- and glucocorticoid-inducible kinase (SGK)1, which in turn stimulates I(Ks), a slow delayed rectifier potassium current that mediates cardiac action potential repolarization. Mutations in I(Ks) channel alpha (KCNQ1, KvLQT1, Kv7.1) or beta (KCNE1, IsK, minK) subunits cause long QT syndrome (LQTS), an inherited cardiac arrhythmia associated with increased risk of sudden death. Together with the GTPases RAB5 and RAB11, SGK1 facilitates membrane recycling of KCNQ1 channels. Here, we show altered SGK1-dependent regulation of LQTS-associated mutant I(Ks) channels. Whereas some mutant KCNQ1 channels had reduced basal activity but were still activated by SGK1, currents mediated by KCNQ1(Y111C) or KCNQ1(L114P) were paradoxically reduced by SGK1. Heteromeric channels coassembled of wild-type KCNQ1 and the LQTS-associated KCNE1(D76N) mutant were similarly downregulated by SGK1 because of a disrupted RAB11-dependent recycling. Mutagenesis experiments indicate that stimulation of I(Ks) channels by SGK1 depends on residues H73, N75, D76, and P77 in KCNE1. Identification of the I(Ks) recycling pathway and its modulation by stress-stimulated SGK1 provides novel mechanistic insight into potentially fatal cardiac arrhythmias triggered by physical or psychological stress.
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17
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Horner JM, Ackerman MJ. Ventricular ectopy during treadmill exercise stress testing in the evaluation of long QT syndrome. Heart Rhythm 2008; 5:1690-4. [PMID: 19084807 DOI: 10.1016/j.hrthm.2008.08.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Accepted: 08/29/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND Long QT syndrome (LQTS) can present with sudden death during exertion. OBJECTIVE The purpose of this study was to determine the diagnostic importance of exercise-induced ventricular ectopy in the evaluation of LQTS. METHODS From 1998 to 2006, 381 patients with a referral diagnosis of LQTS underwent a treadmill exercise stress test. An investigator blinded to both genotype and rendered diagnosis scored the stress tests for the presence of exercise-induced ventricular ectopy. RESULTS The dismissal diagnosis was LQTS in 177 (46%), catecholaminergic polymorphic ventricular tachycardia (CPVT) in 16, miscellaneous cardiac disease in 17, and normal in 171. Exercise-induced ventricular ectopy was detected in 107 (28%) patients. However, only 34 patients (9% overall) had exercise-induced ventricular ectopy greater than single premature ventricular contractions (PVCs). Among the 171 patients dismissed as normal, only 2% had ectopy greater than single PVCs. Among the genotype-positive LQTS patients, no significant ectopy was recorded in 80 with LQT1, compared to 5 (8%) patients with LQT2 and 3 (20%) patients with LQT3 (P <.0001). In contrast, exercise-induced ventricular ectopy beyond single PVCs was far more common among patients with CPVT (14/16 [88%]; P <.0001) and included PVCs in bigeminy in 13 (81%), couplets in 7 (47%), and nonsustained ventricular tachycardia in 3 (19%). Of note, bidirectional VT was not present in any of the 16 patients diagnosed with CPVT, including the 10 with genetically proven, RYR2-mediated CPVT. CONCLUSION Exercise-induced ventricular ectopy exceeding single PVCs was observed in less than 10% of patients referred for LQTS evaluation, including 2% of patients ultimately dismissed as normal. Exercise-induced bigeminy is strongly associated with the presence of significant cardiovascular disease but is far more likely to indicate CPVT than LQTS.
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Affiliation(s)
- Justin M Horner
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota 55905, USA
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18
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Abstract
The rate and force of contraction of the heart are precisely controlled by compartmentalized regulation of cardiac ion channels which determine electrical activities. It is known that modulation of cardiac ion channels, which is caused by drug administration, sympathetic nervous system stimulation and gender difference, can increase risks of lethal arrhythmias in carriers of inherited disease mutations. These modulations are thought to also be involved in common cardiac arrhythmias. Because many signaling molecules are localized within single cells, an understanding of the molecular basis of compartmentalized regulation of cardiac channels is a key for understanding and treating the lethal arrhythmias. In this review, I will discuss molecular mechanisms of compartmentalized regulation of cardiac ion channels via drugs, cAMP and sex hormones.
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Affiliation(s)
- Junko Kurokawa
- Department of Bio-Informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
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19
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Andrássy G, Szabo A, Ferencz G, Trummer Z, Simon E, Tahy A. Mental stress may induce QT-interval prolongation and T-wave notching. Ann Noninvasive Electrocardiol 2007; 12:251-9. [PMID: 17617071 PMCID: PMC6932412 DOI: 10.1111/j.1542-474x.2007.00169.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The effects of active and passive mental stress (PMS) on the QT interval were studied by using an intraindividual regression method of QT-interval correction for heart rate. METHODS Thirty healthy males (age 21.2 +/- 1.8 years) performed a mental arithmetic for 1 minute, which was considered as active mental stress (AMS) because of the performance requirement. A 1-minute unpleasant video clip was used for PMS. Two baseline and two (an early and a late) ECGs were prepared in both mental stress periods. The individual QT-RR relationship was assessed by linear regression analysis of 7-15 (11.0 +/- 1.9) controlled QT-RR data pairs, also obtained from ECGs gained during a successive set of 9 isometric stretching exercises. RESULTS Heart rate has increased significantly at both measurements in response to AMS (P < 0.0001), but not in response to passive stress. QTc significantly prolonged early in AMS (P = 0.0004), then normalized by the end of the period. During PMS, no significant QTc changes were observed. The evolution of bifid T waves was noted in 14 subjects: 8 presented bifid T waves during both AMS and exercise, and 6 during only exercise. CONCLUSIONS AMS and PMS elicit different cardiovascular reactions. Our results indicate that changes in the autonomic tone, probably abrupt sympathetic predominance, may cause QTc prolongation and bifid T waves. This suggests that besides stress quality and intensity, the dynamics of stress application and perception also influence repolarization.
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Affiliation(s)
- Gábor Andrássy
- Department of Cardiology, Saint Francis Hospital, Budapest, Hungary.
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20
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Yada H, Murata M, Shimoda K, Yuasa S, Kawaguchi H, Ieda M, Adachi T, Murata M, Ogawa S, Fukuda K. Dominant Negative Suppression of Rad Leads to QT Prolongation and Causes Ventricular Arrhythmias via Modulation of L-type Ca
2+
Channels in the Heart. Circ Res 2007; 101:69-77. [PMID: 17525370 DOI: 10.1161/circresaha.106.146399] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Disorders of L-type Ca
2+
channels can cause severe cardiac arrhythmias. A subclass of small GTP-binding proteins, the RGK family, regulates L-type Ca
2+
current (
I
Ca,L
) in heterologous expression systems. Among these proteins, Rad (Ras associated with diabetes) is highly expressed in the heart, although its role in the heart remains unknown. Here we show that overexpression of dominant negative mutant Rad (S105N) led to an increase in
I
Ca,L
and action potential prolongation via upregulation of L-type Ca
2+
channel expression in the plasma membrane of guinea pig ventricular cardiomyocytes. To verify the in vivo physiological role of Rad in the heart, a mouse model of cardiac-specific Rad suppression was created by overexpressing S105N Rad, using the α-myosin heavy chain promoter. Microelectrode studies revealed that action potential duration was significantly prolonged with visible identification of a small plateau phase in S105N Rad transgenic mice, when compared with wild-type littermate mice. Telemetric electrocardiograms on unrestrained mice revealed that S105N Rad transgenic mice had significant QT prolongation and diverse arrhythmias such as sinus node dysfunction, atrioventricular block, and ventricular extrasystoles, whereas no arrhythmias were observed in wild-type mice. Furthermore, administration of epinephrine induced frequent ventricular extrasystoles and ventricular tachycardia in S105N Rad transgenic mice. This study provides novel evidence that the suppression of Rad activity in the heart can induce ventricular tachycardia, suggesting that the Rad-associated signaling pathway may play a role in arrhythmogenesis in diverse cardiac diseases.
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Affiliation(s)
- Hirotaka Yada
- Cardiopulmonary Division, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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21
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Bonnemeier H, Ortak J, Bode F, Kurowski V, Reppel M, Weitz G, Barantke M, Schunkert H, Wiegand UKH. Modulation of ventricular repolarization in patients with transient left ventricular apical ballooning: a case control study. J Cardiovasc Electrophysiol 2006; 17:1340-7. [PMID: 17096660 DOI: 10.1111/j.1540-8167.2006.00644.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Even though diffuse T wave inversion and prolongation of the QT interval in the surface electrocardiogram (ECG) have been consistently reported in patients with transient stress-induced left ventricular apical ballooning (AB), ventricular repolarization has not yet been systematically investigated in this clinical entity. BACKGROUND AB, an emerging syndrome that mimics acute ST-segment elevation myocardial infarction (MI), is characterized by reversible left ventricular wall motion abnormalities in the absence of obstructive coronary heart disease and significant QT interval prolongation. METHODS We prospectively enrolled 22 consecutive patients (21 women, median age 65 years) with transient left ventricular AB. A total of 22 age-, gender-, body-mass-index-, and left-ventricular-function-matched patients with acute anterior ST-segment elevation MI undergoing successful direct percutaneous coronary intervention for a proximal occlusion of the LAD, as well as 22 healthy volunteers served as control groups. Beat-to-beat QT interval and QT interval dynamicity were determined from 24-hour Holter ECGs, recorded on the third day after hospital admission. RESULTS There were no significant differences in baseline clinical characteristics, except higher peak enzyme release in MI patients. Compared with MI patients, AB patients exhibited significantly prolonged mean QT intervals and rate-corrected QT intervals (QT: 418 +/- 37 vs 384 +/- 33 msec, P < 0.01; QTcBazett: 446 +/- 40 vs 424 +/- 35 msec, P < 0.05; QTcFridericia: 437 +/- 35 vs 412 +/- 31 msec, P < 0.05). Mean RR intervals tended to be higher in AB patients, without reaching statistical significance (877 +/- 96 vs 831 +/- 102 msec, P = NS). The linear regression slope of QT intervals plotted against RR intervals was significantly flatter in AB patients at both day- and nighttime (QT/RR slopeday: 0.18 +/- 0.04 vs 0.22 +/- 0.06, P < 0.01; QT/RR slopenight: 0.12 +/- 0.03 vs 0.17 +/- 0.05, P < 0.01). CONCLUSION The present study is the first to demonstrate significant differences of QT interval modulation in patients with transient left ventricular AB and acute ST-segment elevation MI. Even though transient AB is associated with a significant QT interval prolongation, rate adaptation of ventricular repolarization (i.e., QT dynamicity) is not significantly altered, suggesting a differential effect of autonomic nervous activity on the ventricular myocardium in transient AB and in acute MI.
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Affiliation(s)
- Hendrik Bonnemeier
- From the Medizinische Klinik II, Universität zu Lübeck, Lübeck, Germany.
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22
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Haapalahti P, Viitasalo M, Perhonen M, Mäkijärvi M, Väänänen H, Oikarinen L, Hekkala AM, Salorinne Y, Swan H, Toivonen L. Ventricular Repolarization and Heart Rate Responses During Cardiovascular Autonomic Function Testing in LQT1 Subtype of Long QT Syndrome. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2006; 29:1122-9. [PMID: 17038145 DOI: 10.1111/j.1540-8159.2006.00506.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND In the most prevalent LQT1 form of inherited long QT syndrome symptoms often occur during abrupt physical or emotional stress. Sympathetic stimulation aggravates repolarization abnormalities in experimental LQT1 models. We hypothesized that autonomic function tests might reveal the abnormal repolarization in asymptomatic LQT1 patients. METHODS We measured heart rates (HRs) and QT intervals in nine asymptomatic carriers of a C-terminal KCNQ1 mutation and 8 unaffected healthy subjects using an approach of global QT values derived from 28 simultaneous electrocardiographic leads on beat-to-beat base during Valsalva maneuver, mental stress, sustained handgrip, and light supine exercise. RESULTS LQT1 patients exhibited impaired shortening of both QTpeak and QTend intervals during autonomic interventions but exaggerated lengthening of the intervals--a QT overshoot--during the recovery phases. The number of tests with a QT overshoot was 2.4 +/- 1.7 in LQT1 patients and 0.8 +/- 0.7 in unaffected subjects (P = 0.02). Valsalva strain prolonged T wave peak to T wave end interval (TPE) in LQT1 but not in unaffected patients. LQT1 patients showed diminished HR acceleration in response to adrenergic challenge whereas HR responses to vagal stimuli were similar in both groups. CONCLUSIONS Standard cardiovascular autonomic provocations induce a QT interval overshoot during recovery in asymptomatic KCNQ1 mutation carriers. Valsalva maneuver causes an exaggerated fluctuation of QT and TPE intervals partly explaining the occurrence of cardiac events during abrupt bursts of autonomic activity in LQT1 patients.
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Affiliation(s)
- Petri Haapalahti
- Department of Cardiology, Helsinki University Hospital, Helsinki, Finland.
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Abstract
BACKGROUND Long QT syndrome (LQTS) is associated with life-threatening cardiac arrhythmias causing syncope and sudden cardiac death, frequently precipitated by physical or psychological stress. TYPES OF STUDIES REVIEWED The authors did a literature review of data published in peer-reviewed medical and dental journals. They also extracted epidemiologic information, correlations between genetic mutations and disease onset and progression, and data regarding outcomes of therapy from published peer-reviewed studies and the cohort population belonging to the International Long QT Syndrome Registry. RESULTS LQTS is diagnosed after an unexpected cardiac event or through QT interval prolongation on an electrocardiogram. Gene mutation identification in LQTS provides insight into respective proarrhythmogenic factors and indicated therapeutic regimens. beta-blockers are the initial treatment for two of the three major forms of LQTS. Patients refractory to beta-antiadrenergic therapy may benefit from one or more of the following: cardiac pacemakers, implanted cardioverter defibrillators and left cardiac sympathetic denervation. CONCLUSIONS Clinical studies are needed to investigate the safety of treating patients in an ambulatory setting. CLINICAL IMPLICATIONS Preventive measures are recommended, including evaluation by a cardiac specialist before any dental intervention, use of anxiolytic protocols, avoidance of drugs that prolong the QT interval, and provision of treatment in a setting in which medical emergencies can be managed expeditiously. Dental treatment in a hospital and use of a general anesthetic administered by anesthesiologists are recommended for procedures in which anxiety and adrenergic stimulation would not be suppressed sufficiently in an ambulatory environment.
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Affiliation(s)
- Jeffrey M Karp
- Division of Pediatric Dentistry, Department of Dentistry, University of Rochester School of Medicine and Dentistry, University of Rochester Medical Center, NY 14620, USA.
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24
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Differences in QT interval determined from multi-lead ambulatory ECG during rest and physical exercise. Biomed Signal Process Control 2006. [DOI: 10.1016/j.bspc.2006.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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25
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Abstract
The congenital long QT syndrome is a rare disease in which inherited mutations of genes coding for ion channel subunits, or channel interacting proteins, delay repolarization of the human ventricle and predispose mutation carriers to the risk of serious or fatal arrhythmias. Though a rare disorder, the long QT syndrome has provided invaluable insight from studies that have bridged clinical and pre-clinical (basic science) medicine. In this brief review, we summarize some of the key clinical and genetic characteristics of this disease and highlight novel findings about ion channel structure, function, and the causal relationship between channel dysfunction and human disease, that have come from investigations of this disorder.
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Affiliation(s)
- R S Kass
- Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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26
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Abstract
Phosphorylation of ion channels plays a critical role in the modulation and amplification of biophysical signals. Kinases and phosphatases have broad substrate recognition sequences. Therefore, the targeting of kinases and phosphatases to specific sites enhances the regulation of diverse signaling events. Ion channel macromolecular complexes can be formed by the association of A-kinase anchoring proteins (AKAPs) or other adaptor proteins directly with the channel. The discovery that leucine/isoleucine zippers play an important role in the recruitment of phosphorylation-modulatory proteins to certain ion channels has permitted the elucidation of specific ion channel macromolecular complexes. Disruption of signaling complexes by genetic defects can lead to abnormal physiological function. This chapter will focus on evidence supporting the concept that ion channel macromolecular complex formation plays an important role in regulating channel function in normal and diseased states. Moreover, we demonstrate that abnormal complex formation may directly lead to abnormal channel regulation by cellular signaling pathways, potentially leading to arrhythmogenesis and cardiac dysfunction.
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Affiliation(s)
- S O Marx
- Division of Cardiology, Department of Medicine and Pharmacology, Columbia University College of Physicians and Surgeons, 630 W 168th St., New York, NY 10032, USA.
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27
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Wehrens XHT. Structural determinants of potassium channel blockade and drug-induced arrhythmias. Handb Exp Pharmacol 2006:123-57. [PMID: 16610343 DOI: 10.1007/3-540-29715-4_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Cardiac K+ channels play an important role in the regulation of the shape and duration of the action potential. They have been recognized as targets for the actions of neurotransmitters, hormones, and anti-arrhythmic drugs that prolong the action potential duration (APD) and increase refractoriness. However, pharmacological therapy, often for the purpose of treating syndromes unrelated to cardiac disease, can also increase the vul- nerability of some patients to life-threatening rhythm disturbances. This may be due to an underlying propensity stemming from inherited mutations or polymorphisms, or structural abnormalities that provide a substrate allowing for the initiation of arrhythmic triggers. A number of pharmacological agents that have proved useful in the treatment of allergic reactions, gastrointestinal disorders, and psychotic disorders, among others, have been shown to reduce repolarizing K+ currents and prolong the Q-T interval on the electrocardiogram. Understanding the structural determinants of K+ channel blockade might provide new insights into the mechanism and rate-dependent effects of drugs on cellular physiology. Drug-induced disruption of cellular repolarization underlies electrocardiographic abnormalities that are diagnostic indicators of arrhythmia susceptibility.
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Affiliation(s)
- X H T Wehrens
- Center for Molecular Cardiology, Dept. of Physiology and Cellular Biophysics, College of Physicians and Surgeons of Columbia University, 630 West 168th Street, P&S 9-401, New York, NY 10032, USA.
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28
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Abstract
Long QT syndrome, a rare genetic disorder associated with life-threatening arrhythmias, has provided a wealth of information about fundamental mechanisms underlying human cardiac electrophysiology that has come about because of truly collaborative interactions between clinical and basic scientists. Our understanding of the mechanisms that control the critical plateau and repolarization phases of the human ventricular action potential has been raised to new levels through these studies, which have clarified the manner in which both potassium and sodium channels regulate this critical period of electrical activity.
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Affiliation(s)
- Arthur J Moss
- Heart Research Follow-up Program, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
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Chen L, Kurokawa J, Kass RS. Phosphorylation of the A-kinase-anchoring Protein Yotiao Contributes to Protein Kinase A Regulation of a Heart Potassium Channel. J Biol Chem 2005; 280:31347-52. [PMID: 16002409 DOI: 10.1074/jbc.m505191200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Regulation of the heart by the sympathetic nervous system, fundamental to the physiological response to stress and exercise, requires coordinated phosphorylation of multiple downstream molecular targets, including the I(Ks) (slowly activating potassium current) channel. Sympathetic nervous system stimulation increases intracellular cAMP for which targeted regulation is directed in large part by distinct scaffold or anchoring proteins. Yotiao is an A-kinase-anchoring protein (AKAP) that recruits the cyclic AMP-dependent protein kinase (protein kinase A (PKA)) and protein phosphatase 1 to the carboxyl terminus of the I(Ks) channel to form a molecular complex and control its phosphorylation state, crucial to the cardiac cellular response to sympathetic nervous system stimulation. Here we report that Yotiao itself is a substrate for PKA phosphorylation, and we identify a Yotiao amino-terminal (N-T) residue (Ser-43) that is PKA-phosphorylated in response to beta-adrenergic receptor stimulation. The replacement of Ser-43 by Ala ablates the PKA phosphorylation of N-T Yotiao and markedly diminishes the functional response of the wild type and pseudo-phosphorylated I(Ks) channel to cAMP but neither prevents the PKA phosphorylation of KCNQ1 nor its binding to Yotiao. These results suggest, for the first time, a critical role for the PKA phosphorylation of an AKAP in the functional regulation of an ion channel protein and postphosphorylation allosteric modulation of the I(Ks) channel by Yotiao.
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Affiliation(s)
- Lei Chen
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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30
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Hulme JT, Scheuer T, Catterall WA. Regulation of cardiac ion channels by signaling complexes: role of modified leucine zipper motifs. J Mol Cell Cardiol 2005; 37:625-31. [PMID: 15350835 DOI: 10.1016/j.yjmcc.2004.04.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2004] [Revised: 01/15/2004] [Accepted: 04/23/2004] [Indexed: 10/26/2022]
Abstract
Modulation of ion channels by protein phosphorylation is a dynamic process precisely controlled by the opposing actions of protein kinases and phosphoprotein phosphatases. It is well accepted that the targeting and localization of such signaling enzymes to discrete subcellular compartments or substrates is an important regulatory mechanism ensuring specificity of signaling events in response to local stimuli. Compartmentalization of these enzymes is achieved through association with anchoring or adaptor proteins that target them to subcellular organelles or tether them directly to target substrates via protein-protein interactions. Recently, a novel role for modified leucine zipper motifs in targeting kinases and phosphatases via anchoring proteins has been described for three families of cardiac ion channels: ryanodine-sensitive calcium (Ca(2+)) release channels, voltage-gated Ca(2+) channels, and delayed rectifier potassium (K(+)) channels. This review will summarize the recent advances made on the regulation of cardiac ion channels by these macromolecular signaling complexes in the normal and diseased heart.
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Affiliation(s)
- Joanne T Hulme
- Department of Pharmacology, University of Washington, Box 357280, Seattle, WA 98195 7280, USA
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31
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Kurokawa J, Motoike HK, Rao J, Kass RS. Regulatory actions of the A-kinase anchoring protein Yotiao on a heart potassium channel downstream of PKA phosphorylation. Proc Natl Acad Sci U S A 2004; 101:16374-8. [PMID: 15528278 PMCID: PMC525330 DOI: 10.1073/pnas.0405583101] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A-kinase anchoring proteins (AKAPs) are thought to be passive members of protein complexes that coordinate the association of cAMP-dependent protein kinase A (PKA) with cellular substrates to facilitate targeted PKA protein phosphorylation. I(Ks), the slow heart potassium current, is carried by the I(Ks) potassium channel, a substrate for PKA phosphorylation in response to sympathetic nerve stimulation, is a macromolecular complex that includes the KCNQ1 alpha subunit, the KCNE1 regulatory subunit, and the AKAP Yotiao. Disruption of this regulation by mutation in the long QT syndrome is associated with elevated risk of sudden death. Here, we have studied the effects of the AKAP Yotiao on the function of the I(Ks) channel that had been mutated to simulate channel phosphorylation, and we report direct AKAP-mediated alteration of channel function distinct from its role in the coordination of channel phosphorylation by PKA. These data reveal previously undescribed actions of Yotiao that occur subsequent to channel phosphorylation and provide evidence that this adaptor protein also may serve as an effector in regulating this important ion channel.
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Affiliation(s)
- Junko Kurokawa
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, USA
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32
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Attari M, Dhala A. Role of invasive and noninvasive testing in risk stratification of sudden cardiac death in children and young adults: an electrophysiologic perspective. Pediatr Clin North Am 2004; 51:1355-78. [PMID: 15331288 DOI: 10.1016/j.pcl.2004.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Sudden cardiac death is a rare, but devastating, event in the young population. Arrhythmia is the mechanism of death in many cases. In addition to clinical history, noninvasive and invasive tests can be used to identify patients who are at risk. Although these tools are not perfect, they can prove valuable if used in proper clinical circumstances. An overview of these tests is presented.
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Affiliation(s)
- Mehran Attari
- Electrophysiology Laboratories, Cardiovascular Disease Section, St. Luke's and Aurora Sinai Medical Centers, University of Wisconsin Medical School-Milwaukee Clinical Campus, 2801 West Kinnickinnic River Parkway, Milwaukee, WI 53215, USA
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33
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Clancy CE, Kurokawa J, Tateyama M, Wehrens XHT, Kass RS. K+ channel structure-activity relationships and mechanisms of drug-induced QT prolongation. Annu Rev Pharmacol Toxicol 2003; 43:441-61. [PMID: 12540747 DOI: 10.1146/annurev.pharmtox.43.100901.140245] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Pharmacological intervention, often for the purpose of treating syndromes unrelated to cardiac disease, can increase the vulnerability of some patients to life-threatening rhythm disturbances. This may be due to an underlying propensity stemming from genetic defects or polymorphisms, or structural abnormalities that provide a substrate allowing for the initiation of arrhythmic triggers. A number of pharmacological agents that have proven useful in the treatment of allergic reactions, gastrointestinal disorders, and psychotic disorders, among others, have been shown to reduce repolarizing K(+) currents and prolong the QT interval on the electrocardiogram. Understanding the structural determinants of K(+) channel blockade may provide new insights into the mechanism and rate-dependent effects of drugs on cellular physiology. Drug-induced disruption of cellular repolarization underlies electrocardiographic abnormalities that are diagnostic indicators of arrhythmia susceptibility.
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Affiliation(s)
- Colleen E Clancy
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
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34
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Kurokawa J, Chen L, Kass RS. Requirement of subunit expression for cAMP-mediated regulation of a heart potassium channel. Proc Natl Acad Sci U S A 2003; 100:2122-7. [PMID: 12566567 PMCID: PMC149969 DOI: 10.1073/pnas.0434935100] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Beta-adrenergic receptor stimulation increases heart rate and shortens ventricular action-potential duration, the latter effect due in part to a cAMP-dependent increase in the slow outward potassium current (I(Ks)). Mutations in either KCNQ1 or KCNE1, the I(Ks) subunits, are associated with variants (LQT-1 and LQT-5) of the congenital long QT syndrome. We now show that cAMP-mediated functional regulation of KCNQ1/KCNE1 channels, a consequence of cAMP-dependent protein kinase A phosphorylation of the KCNQ1 N terminus, requires coexpression of KCNQ1 with KCNE1, its auxiliary subunit. Further, at least two KCNE1 mutations linked to LQT-5 (D76N and W87R) cause functional disruption of cAMP-mediated KCNQ1/KCNE1-channel regulation despite the response of the substrate protein (KCNQ1) to protein kinase A phosphorylation. Transduction of protein phosphorylation into physiologically necessary channel function represents a previously uncharacterized role for the KCNE1 auxiliary subunit, which can be disrupted in LQT-5.
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Affiliation(s)
- Junko Kurokawa
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, 630 West 168th Street, New York, NY 10032, USA
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35
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Batchvarov VN, Ghuran A, Smetana P, Hnatkova K, Harries M, Dilaveris P, Camm AJ, Malik M. QT-RR relationship in healthy subjects exhibits substantial intersubject variability and high intrasubject stability. Am J Physiol Heart Circ Physiol 2002; 282:H2356-63. [PMID: 12003846 DOI: 10.1152/ajpheart.00860.2001] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recently, it was demonstrated that the QT-RR relationship pattern varies significantly among healthy individuals. We compared the intra- and interindividual variations of the QT-RR relationship. Twenty-four-hour 12-lead digital electrocardiograms (ECGs; SEER MC, GE Marquette; 10-s ECG recorded every 30 s) were obtained at baseline and after 24 h, 1 wk, and 1 mo in 75 healthy subjects (42 women, 33 men, age 27.9 +/- 9.6 vs. 26.8 +/- 7.5 yr, P = not significant). QT interval was measured automatically in each ECG by six different algorithms, and the mean of the six measurements was analyzed. In each recording of each individual, QT-RR relationship was assessed by 10 different regression models including linear (QT = beta + alpha x RR) and parabolic (QT = beta x RR(alpha)) models. Standard deviations (SDs) of regression parameters alpha and beta of consecutive recordings of each individual were compared with SD of the individual means. Intrasubject stability and interindividual variability were further tested by ANOVA. With all models, intraindividual SDs of the regression parameters were highly significantly smaller than SD of individual means (P < 10(-5)-10(-9)). The intrasubject stability was further confirmed by ANOVA (P < 10(-19)-10(-30)). The QT-RR relationship exhibits substantial intersubject variability as well as a high intrasubject stability. This has practical implications for a precise estimation of the heart rate-corrected QT interval in which optimized subject-specific rate correction formulas should be used.
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Affiliation(s)
- Velislav N Batchvarov
- Department of Cardiological Sciences, St. George's Hospital Medical School, London SW17 0RE, United Kingdom.
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