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1.
Pacing Clin Electrophysiol ; 42(7): 965-969, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31045260

RESUMO

BACKGROUND: Boston Scientific (Marlborough, MA, USA) implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-Ds) manufactured between 2008 and 2014 are potentially subject to premature battery depletion through a low-voltage capacitor malfunction occurring as a result of hydrogen buildup within the device. Although some of these devices are currently under advisory, other devices manufactured during this timeframe carry a lower risk of the same malfunction. These same devices are known to have superior longevity in general, and the overall mean lifespan of the devices remains long. METHODS: All patients implanted or followed at our two centers who experienced premature battery depletion and had a Boston Scientific ICD or CRT-D potentially at risk for low-voltage capacitor malfunction were studied retrospectively. RESULTS: Nineteen out of 838 patients (2.3%) with devices potentially at risk have had premature battery depletion: 5.7% of those under advisory and 1.1% of those not under advisory. None of our patients had compromised therapy, and all had >27 days of projected battery longevity remaining. CONCLUSIONS: Undetected premature battery depletion in this population of ICDs has the potential to expose a patient to an interval of time where the device is unable to provide therapy. However, with enrollment in remote monitoring, regular follow-up, and attention to audible alerts, the risk of therapy loss due to low-voltage state can be effectively mitigated. For these reasons, prophylactic generator replacement is not recommended.

3.
Sleep Breath ; 23(4): 1275-1281, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30887227

RESUMO

PURPOSE: P wave characteristics change during simulated apneic events in individuals with atrial fibrillation (AF). This study sought to assess whether similar changes occur during nocturnal respiratory events in patients with AF and obstructive sleep apnea (OSA). METHODS: Thirty-five individuals with severe OSA who underwent formal polysomnography and subsequent AF ablation were compared to a matched group without AF. Electrocardiographic segments from each polysomnogram corresponding to the following events were identified: period of wakefulness closest to the initial onset of sleep (baseline-awake), first respiratory event, respiratory event with the lowest nadir oxygen saturation, longest respiratory event, and last respiratory event. Signal-averaged P wave duration and signal-averaged positive P wave area (amplitude*duration for positive P wave amplitudes) were extracted using custom software. P wave characteristics during respiratory events and the baseline-awake condition were compared. RESULTS: Compared to the baseline-awake condition, the signal-averaged positive P wave area was significantly greater during the longest event and the event with the lowest oxygen saturation in those with AF, but not in those without AF. There were no significant differences in signal-averaged P wave duration for any respiratory event compared to the baseline-awake condition, regardless of AF status. CONCLUSION: In patients with paroxysmal AF and obstructive sleep apnea, the signal-averaged positive P wave area is greater during certain respiratory events than during wakefulness. This finding may reflect the acute impact on right atrial volume of increased venous return associated with respiratory events and could be useful to assess AF risk in sleep apnea and to monitor response to treatment.

4.
J Clin Sleep Med ; 14(11): 1953-1957, 2018 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-30373693

RESUMO

ABSTRACT: Sleep-disordered breathing (SDB) is a contributor to atrial fibrillation (AF) and treatment of obstructive sleep apnea can reduce the recurrence of AF following catheter ablation. However, the effect of AF therapies on measures of SDB severity is less robustly described. We present the case of a middle-aged man with SDB and persistent AF who exhibited improvement in SDB metrics, as characterized by data downloaded from his auto-titrating continuous positive airway pressure (AutoCPAP) machine, very shortly following procedures that restored sinus rhythm. Between procedures, when his rhythm reverted to AF, the downloaded parameters suggested more SDB events. After catheter ablation, the patient maintained sinus rhythm and the improvement in SDB metrics was sustained as well. This case provides support in favor of a bidirectional relationship between SDB and AF and suggests that data available from PAP machines may be useful in serial assessment of SDB status relative to heart rhythm.


Assuntos
Fibrilação Atrial/terapia , Respiração com Pressão Positiva , Síndromes da Apneia do Sono/terapia , Idoso , Ablação por Cateter , Cardioversão Elétrica , Humanos , Masculino , Polissonografia , Recidiva
6.
J Cardiovasc Electrophysiol ; 26(10): 1111-6, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26222980

RESUMO

INTRODUCTION: Cardiac implantable electronic device (CIED) infections are potentially preventable complications associated with high morbidity, mortality, and cost. A recently developed bio-absorbable antibacterial envelope (TYRX™-A) might prevent CIED infections in high-risk subjects. However, data regarding safety and efficacy have not been published. METHODS AND RESULTS: In a single-center retrospective cohort study, we compared the prevalence of CIED infections among subjects with ≥2 risk factors treated with the TYRX™-A envelope (N = 135), the nonabsorbable TYRX™ envelope (N = 353), and controls who did not receive an envelope (N = 636). Infection was ascertained by individual chart review. The mean (95% confidence interval) number of risk factors was 3.08 (2.84-3.32) for TYRX™-A, 3.20 (3.07-3.34) for TYRX™, and 3.09 (2.99-3.20) for controls, P = 0.3. After a minimum 300 days follow-up, the prevalence of CIED infection was 0 (0%) for TYRX™-A, 1 (0.3%) for TYRX™, and 20 (3.1%) for controls (P = 1 for TYRX™-A vs. TYRX™, P = 0.03 for TYRX™-A vs. controls, and P = 0.002 for TYRX™ vs. controls). In a propensity score-matched cohort of 316 recipients of either envelope and 316 controls, the prevalence of infection was 0 (0%) and 9 (2.8%), respectively, P = 0.004. When limited to 122 TYRX™-A recipients and 122 propensity-matched controls, the prevalence of CIED infections was 0 (0%) and 5 (4.1%), respectively, P = 0.024. CONCLUSIONS: Among high-risk subjects, the TYRX™-A bio-absorbable envelope was associated with a very low prevalence of CIED related infections that was comparable to that seen with the nonabsorbable envelope.


Assuntos
Antibacterianos/administração & dosagem , Desfibriladores Implantáveis/estatística & dados numéricos , Implantes de Medicamento/administração & dosagem , Marca-Passo Artificial/estatística & dados numéricos , Infecções Relacionadas à Prótese/epidemiologia , Infecções Relacionadas à Prótese/prevenção & controle , Implantes Absorvíveis/estatística & dados numéricos , Idoso , Causalidade , Estudos de Coortes , Preparações de Ação Retardada/administração & dosagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Infecções Relacionadas à Prótese/diagnóstico , Estudos Retrospectivos , Fatores de Risco , Distribuição por Sexo , Taxa de Sobrevida , Tennessee/epidemiologia , Resultado do Tratamento
7.
Am J Cardiol ; 115(6): 763-70, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25633190

RESUMO

There is wide variation in the management of patients with atrial fibrillation (AF) in the emergency department (ED). We aimed to derive and internally validate the first prospective, ED-based clinical decision aid to identify patients with AF at low risk for 30-day adverse events. We performed a prospective cohort study at a university-affiliated tertiary-care ED. Patients were enrolled from June 9, 2010, to February 28, 2013, and followed for 30 days. We enrolled a convenience sample of patients in ED presenting with symptomatic AF. Candidate predictors were based on ED data available in the first 2 hours. The decision aid was derived using model approximation (preconditioning) followed by strong bootstrap internal validation. We used an ordinal outcome hierarchy defined as the incidence of the most severe adverse event within 30 days of the ED evaluation. Of 497 patients enrolled, stroke and AF-related death occurred in 13 (3%) and 4 (<1%) patients, respectively. The decision aid included the following: age, triage vitals (systolic blood pressure, temperature, respiratory rate, oxygen saturation, supplemental oxygen requirement), medical history (heart failure, home sotalol use, previous percutaneous coronary intervention, electrical cardioversion, cardiac ablation, frequency of AF symptoms), and ED data (2 hours heart rate, chest radiograph results, hemoglobin, creatinine, and brain natriuretic peptide). The decision aid's c-statistic in predicting any 30-day adverse event was 0.7 (95% confidence interval 0.65, 0.76). In conclusion, in patients with AF in the ED, Atrial Fibrillation and Flutter Outcome Risk Determination provides the first evidence-based decision aid for identifying patients who are at low risk for 30-day adverse events and candidates for safe discharge.


Assuntos
Fibrilação Atrial/complicações , Fibrilação Atrial/terapia , Técnicas de Apoio para a Decisão , Serviço Hospitalar de Emergência , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/etiologia , Idoso , Algoritmos , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/mortalidade , Feminino , Seguimentos , Hospitais Universitários , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Reprodutibilidade dos Testes , Medição de Risco , Fatores de Risco , Acidente Vascular Cerebral/mortalidade , Acidente Vascular Cerebral/terapia , Fatores de Tempo , Resultado do Tratamento , Estados Unidos
8.
Circulation ; 130(22): 1936-1943, 2014 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-25294783

RESUMO

BACKGROUND: Congenital Long QT syndrome (LQTS) is an arrhythmogenic disorder that causes syncope and sudden death. Although its genetic basis has become well-understood, the mechanisms whereby mutations translate to arrhythmia susceptibility in the in situ human heart have not been fully defined. We used noninvasive ECG imaging to map the cardiac electrophysiological substrate and examine whether LQTS patients display regional heterogeneities in repolarization, a substrate that promotes arrhythmogenesis. METHODS AND RESULTS: Twenty-five subjects (9 LQT1, 9 LQT2, 5 LQT3, and 2 LQT5) with genotype and phenotype positive LQTS underwent ECG imaging. Seven normal subjects provided control. Epicardial maps of activation, recovery times, activation-recovery intervals, and repolarization dispersion were constructed. Activation was normal in all patients. However, recovery times and activation-recovery intervals were prolonged relative to control, indicating delayed repolarization and abnormally long action potential duration (312±30 ms versus 235±21 ms in control). Activation-recovery interval prolongation was spatially heterogeneous, with repolarization gradients much steeper than control (119±19 ms/cm versus 2.0±2.0 ms/cm). There was variability in steepness and distribution of repolarization gradients between and within LQTS types. Repolarization gradients were steeper in symptomatic patients (130±27 ms/cm in 12 symptomatic patients versus 98±19 ms/cm in 13 asymptomatic patients; P<0.05). CONCLUSIONS: LQTS patients display regions with steep repolarization dispersion caused by localized action potential duration prolongation. This defines a substrate for reentrant arrhythmias, not detectable by surface ECG. Steeper dispersion in symptomatic patients suggests a possible role for ECG imaging in risk stratification.


Assuntos
Eletrocardiografia/métodos , Mapeamento Epicárdico/métodos , Síndrome do QT Longo/diagnóstico , Síndrome do QT Longo/fisiopatologia , Adolescente , Adulto , Criança , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
9.
Am J Cardiol ; 113(10): 1668-73, 2014 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-24666620

RESUMO

International guidelines do not specify what testing should be performed during emergency department (ED) evaluations for patients presenting with an exacerbation of previously diagnosed atrial fibrillation (AF). We hypothesized that low CHADS2 and CHA2DS2-VASc scores predict normal routine diagnostic testing in these patients. We conducted an analysis within a prospective observational cohort study at a university-affiliated hospital. We included patients with previously diagnosed AF and who presented to the ED primarily for an AF-related complaint. Logistic regression was used to analyze the association between CHADS2 and CHA2DS2-VASc scores and abnormal results for blood counts, electrolytes, cardiac markers, thyroid function, and chest x-rays. We included 216 patients in this analysis. The odds ratios (95% confidence interval) for each point increase in CHADS2 for abnormal blood counts, electrolytes, troponin I, brain natriuretic peptide, thyroid function, and chest x-ray were 1.28 (0.99 to 1.65), 1.48 (1.19 to 1.84), 1.42 (1.10 to 1.82), 1.66 (1.15 to 2.41), 0.95 (0.70 to 1.29), and 1.17 (0.94 to 1.44), respectively. The corresponding odds ratios (95% confidence interval) for each point increase in CHA2DS2-VASc were 1.17 (0.96 to 1.42), 1.27 (1.09 to 1.49), 1.30 (1.07 to 1.57), 1.57 (1.18 to 2.10), 0.98 (0.79 to 1.22), and 1.14 (0.97 to 1.33), respectively. Among ED patients with established AF who underwent evaluation for acutely symptomatic AF, nearly 3/4 of routine diagnostic tests return to normal. In conclusion, patients with CHADS2 or CHA2DS2-VASc score of 0 have the lowest likelihood of abnormal studies and may represent an easily identifiable group of patients who need fewer ED tests.


Assuntos
Fibrilação Atrial/complicações , Técnicas de Diagnóstico Cardiovascular/estatística & dados numéricos , Serviço Hospitalar de Emergência , Tromboembolia/diagnóstico , Doença Aguda , Idoso , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/fisiopatologia , Feminino , Seguimentos , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Razão de Chances , Valor Preditivo dos Testes , Prognóstico , Estudos Prospectivos , Recidiva , Reprodutibilidade dos Testes , Medição de Risco/métodos , Fatores de Risco , Taxa de Sobrevida , Tromboembolia/epidemiologia , Tromboembolia/etiologia
10.
Am J Cardiol ; 110(9): 1315-21, 2012 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-22840846

RESUMO

Symptomatic bradycardia may complicate atrial fibrillation (AF) and necessitate a permanent pacemaker. Identifying patients at increased risk for symptomatic bradycardia may reduce associated morbidities and health care costs. The aim of this study was to investigate predictors for developing bradycardia requiring a permanent pacemaker in patients with AF. The records of all patients treated for AF or atrial flutter in an academic hospital's emergency department from August 1, 2005, to July 31, 2008, were reviewed. Survival and the presence of a pacemaker as of November 1, 2011, were determined. Cases were defined as patients with pacemakers placed for bradycardia after their AF diagnoses. Patients without pacemakers who were followed constituted the control group. Variables for the logistic regression analysis were identified a priori. A post hoc model was fit adjusting for AF type and atrioventricular nodal blocker use. Of the 362 patients in the cohort, 119 cases had permanent pacemakers implanted for bradycardia after AF diagnosis, and 243 controls were alive without pacemakers. The median follow-up time was 4.5 years (interquartile range 3.8 to 5.4). Odds ratios were determined for age at the time of AF diagnosis (1.02, 95% confidence interval [CI] 1 to 1.04), female gender (1.58, 95% CI 0.95 to 2.63), previous heart failure (2.72, 95% CI 1.47 to 5.01), and African American race (0.33, 95% CI 0.12 to 0.94). The post hoc model identified permanent AF (odds ratio 2.99, 95% CI 1.61 to 5.57) and atrioventricular nodal blocker use (odds ratio 1.43, 95% CI 0.85 to 2.4). In conclusion, in patients with AF, heart failure and permanent AF each nearly triple the odds of developing bradycardia requiring a permanent pacemaker; although not statistically significant, our results suggest that women are more likely and African Americans less likely to develop bradycardia requiring pacemaker implantation.


Assuntos
Fibrilação Atrial/epidemiologia , Fibrilação Atrial/terapia , Bradicardia/epidemiologia , Bradicardia/terapia , Marca-Passo Artificial/efeitos adversos , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Fibrilação Atrial/diagnóstico , Bradicardia/etiologia , Estimulação Cardíaca Artificial/efeitos adversos , Estimulação Cardíaca Artificial/métodos , Estudos de Casos e Controles , Intervalos de Confiança , Eletrocardiografia/métodos , Feminino , Seguimentos , Humanos , Incidência , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Estudos Retrospectivos , Fatores de Risco , Índice de Gravidade de Doença , Distribuição por Sexo , Análise de Sobrevida , Resultado do Tratamento
12.
J Mol Cell Cardiol ; 48(1): 181-90, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19646991

RESUMO

Mutations in multiple genes have been implicated in familial atrial fibrillation (AF), but the underlying mechanisms, and thus implications for therapy, remain ill-defined. Among 231 participants in the Vanderbilt AF Registry, we found a mutation in KCNQ1 (encoding the alpha-subunit of slow delayed rectifier potassium current [I(Ks)]) and separately a mutation in natriuretic peptide precursor A (NPPA) gene (encoding atrial natriuretic peptide, ANP), both segregating with early onset lone AF in different kindreds. The functional effects of these mutations yielded strikingly similar I(Ks) "gain-of-function." In Chinese Hamster Ovary (CHO) cells, coexpression of mutant KCNQ1 with its ancillary subunit KCNE1 generated approximately 3-fold larger currents that activated much faster than wild-type (WT)-I(Ks). Application of the WT NPPA peptide fragment produced similar changes in WT-I(Ks), and these were exaggerated with the mutant NPPA S64R peptide fragment. Anantin, a competitive ANP receptor antagonist, completely inhibited the changes in I(Ks) gating observed with NPPA S64R. Computational simulations identified accelerated transitions into open states as the mechanism for variant I(Ks) gating. Incorporating these I(Ks) changes into computed human atrial action potentials (AP) resulted in 37% shortening (120 vs. 192 ms at 300 ms cycle length), reflecting loss of the phase II dome which is dependent on L-type calcium channel current. We found striking functional similarities due to mutations in KCNQ1 and NPPA genes which led to I(Ks) "gain-of-function", atrial AP shortening, and consequently altered calcium current as a common mechanism between diverse familial AF syndromes.


Assuntos
Fibrilação Atrial/genética , Potássio/metabolismo , Potenciais de Ação/genética , Potenciais de Ação/fisiologia , Adulto , Fator Natriurético Atrial/genética , Simulação por Computador , Eletrofisiologia , Feminino , Humanos , Canal de Potássio KCNQ1/genética , Masculino , Pessoa de Meia-Idade , Mutação , Fenótipo , Reação em Cadeia da Polimerase
13.
J Mol Cell Cardiol ; 44(3): 571-81, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18222468

RESUMO

Life-threatening arrhythmias have been suspected as one cause of the sudden infant death syndrome (SIDS), and this hypothesis is supported by the observation that mutations in arrhythmia susceptibility genes occur in 5-10% of cases. However, the functional consequences of cardiac potassium channel gene mutations associated with SIDS and how these alleles might mechanistically predispose to sudden death are unknown. To address these questions, we studied four missense KCNH2 (encoding HERG) variants, one compound KCNH2 genotype, and a missense KCNQ1 mutation all previously identified in Norwegian SIDS cases. Three of the six variants exhibited functional impairments while three were biophysically similar to wild-type channels (KCNH2 variants V279M, R885C, and S1040G). When co-expressed with WT-HERG, R273Q and K897T/R954C generated currents resembling the rapid component of the cardiac delayed rectifier current (I(Kr)) but with significantly diminished amplitude. Action potential modeling demonstrated that this level of functional impairment was sufficient to evoke increased action potential duration and pause-dependent early afterdepolarizations. By contrast, KCNQ1-I274V causes a gain-of-function in I(Ks) characterized by increased current density, faster activation, and slower deactivation leading to accumulation of instantaneous current upon repeated stimulation. Action potential simulations using a Markov model of heterozygous I274V-I(Ks) incorporated into the Luo-Rudy (LRd) ventricular cell model demonstrated marked rate-dependent shortening of action potential duration predicting a short QT phenotype. Our results indicate that certain potassium channel mutations associated with SIDS confer overt functional defects consistent with either LQTS or SQTS, and further emphasize the role of congenital arrhythmia susceptibility in this syndrome.


Assuntos
Canais de Potássio Éter-A-Go-Go/genética , Mutação de Sentido Incorreto , Morte Súbita do Lactente/genética , Animais , Células CHO , Cricetinae , Cricetulus , Canal de Potássio ERG1 , Eletrofisiologia , Canais de Potássio Éter-A-Go-Go/fisiologia , Predisposição Genética para Doença , Humanos , Recém-Nascido , Síndrome do QT Longo/genética , Síndrome do QT Longo/fisiopatologia , Cadeias de Markov , Potenciais da Membrana , Transfecção
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