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QRS interval [keywords]
- Real Time QRS Detection Based on M-ary Likelihood Ratio Test on the DFT Coefficients. [Journal Article]
- PLoS One 2014; 9(10):e110629.
This paper shows an adaptive statistical test for QRS detection of electrocardiography (ECG) signals. The method is based on a M-ary generalized likelihood ratio test (LRT) defined over a multiple observation window in the Fourier domain. The motivations for proposing another detection algorithm based on maximum a posteriori (MAP) estimation are found in the high complexity of the signal model proposed in previous approaches which i) makes them computationally unfeasible or not intended for real time applications such as intensive care monitoring and (ii) in which the parameter selection conditions the overall performance. In this sense, we propose an alternative model based on the independent Gaussian properties of the Discrete Fourier Transform (DFT) coefficients, which allows to define a simplified MAP probability function. In addition, the proposed approach defines an adaptive MAP statistical test in which a global hypothesis is defined on particular hypotheses of the multiple observation window. In this sense, the observation interval is modeled as a discontinuous transmission discrete-time stochastic process avoiding the inclusion of parameters that constraint the morphology of the QRS complexes.
- The role of fQRS in coronary artery disease : A meta-analysis of observational studies. [JOURNAL ARTICLE]
- Herz 2014 Oct 23.
Experimental and clinical studies have suggested that the presence of fragmented QRS complex (fQRS) is associated with various cardiovascular diseases. fQRS may predict major adverse cardiovascular events (MACE). The current meta-analysis was performed using clinical outcome studies to evaluate the role of fQRS in coronary artery disease (CAD).A systematic search of electronic databases (Cochrane, Medline, Embase and Pubmed) from their inception to April 2014 was performed. Data were extracted from applicable articles to evaluate the prognostic value of fQRS in CAD.A total of 16 observational studies about fQRS and CAD (n = 3,997 patients) were identified. Compared with the non-fQRS group, MACE and mortality were significantly higher in the fQRS group -odds ratios (OR) 3.19, 95 % confidence interval (95 % CI) [2.3, 4.42], p < 0.00001; OR 2.24, 95 % CI [1.71, 2.94], p < 0.0001. Patients developed Q waves, anterior-wall myocardial infarction (MI), and low left ventricular ejection fraction (LVEF) more frequently in the fQRS group than in the non-fQRS group-OR 2.59, 95 % CI [1.76, 3.81], p < 0.00001; OR 2.43, 95 % CI [1.07, 5.52], p = 0.03; OR - 6.43, 95 % CI [- 9.11, - 3.74], p < 0.00001.Based on current evidence, fQRS was associated with increased MACE, mortality, Q waves, anterior-wall MI, and decreased LVEF in CAD. These findings show that fQRS is a reliable marker in CAD.
- Negative Effects of Acute Sleep Deprivation on Left Ventricular Functions and Cardiac Repolarization in Healthy Young Adults. [JOURNAL ARTICLE]
- Pacing Clin Electrophysiol 2014 Oct 29.
Sleep deprivation (SD) is associated with an increased incidence of adverse cardiovascular events, we aimed to determine the impact of acute SD on structural and functional alterations of the left ventricle (LV) and on electrocardiogram (ECG) markers including T wave peak-to-end interval (TpTe), QT interval, and TpTe/QT ratio in healthy subjects after a night of SD.The study population consisted of 40 healthy young adults (19 males, 21 females; mean age: 28.2 ± 3.86 years). Echocardiographic images and ECGs were obtained from the participants after a night of regular sleep (RS) and SD. The average sleep time of the subjects was 6.67 ± 1.76 hours during RS and 1.25 ± 0.74 hours during a night of SD.The myocardial performance index, isovolumic relaxation time, and deceleration time values were significantly higher after SD. In addition, the corrected TpTe interval, corrected QT interval (QTc) max, and TpTe/QT ratio were significantly increased after a night of SD when compared with a night of RS (78.5 ± 6.8 ms vs 70.7 ± 7.6 ms, P < 0.001; 407.5 ± 18.6 ms vs 395.07 ± 21.3 ms, P = 0.001; and 0.189 ± 0.014 ms vs 0. 0.179 ± 0.016 ms, P < 0.001, respectively). However, subjects had similar QTp interval values (defined as beginning of the QRS complex to peak of the T wave) after a night of SD as a night of RS (294.6 ± 19.0 vs 291.9 ± 18.5, P = 233).Our crossover study revealed the presence of subclinical LV diastolic functional changes and increased QT intervals, TpTe intervals, and TpTe/QT ratios in healthy young adults after one night SD. Therefore, the increased QT interval occurred secondary to the increased TpTe interval in this population.
- Value of the Qrs-T Angle in Predicting the Induction of Ventricular Tachyarrhythmias in Patients with Chagas Disease. [JOURNAL ARTICLE]
- Arq Bras Cardiol 2014 Oct 28.:12.
Background: The QRS-T angle correlates with prognosis in patients with heart failure and coronary artery disease, reflected by an increase in mortality proportional to an increase in the difference between the axes of the QRS complex and T wave in the frontal plane. The value of this correlation in patients with Chagas heart disease is currently unknown. Objective: Determine the correlation of the QRS-T angle and the risk of induction of ventricular tachycardia / ventricular fibrillation (VT / VF) during electrophysiological study (EPS) in patients with Chagas disease. Methods: Case-control study at a tertiary center. Patients without induction of VT / VF on EPS were used as controls. The QRS-T angle was categorized as normal (0-105º), borderline (105-135º) or abnormal (135-180º). Differences between groups for continuous variables were analyzed with the t test or Mann-Whitney test, and for categorical variables with Fisher's exact test. P values < 0.05 were considered significant. Results: Of 116 patients undergoing EPS, 37.9% were excluded due to incomplete information / inactive records or due to the impossibility to correctly calculate the QRS-T angle (presence of left bundle branch block and atrial fibrillation). Of 72 patients included in the study, 31 induced VT / VF on EPS. Of these, the QRS-T angle was normal in 41.9%, borderline in 12.9% and abnormal in 45.2%. Among patients without induction of VT / VF on EPS, the QRS-T angle was normal in 63.4%, borderline in 14.6% and abnormal in 17.1% (p = 0.04). When compared with patients with normal QRS-T angle, those with abnormal angle had a fourfold higher risk of inducing ventricular tachycardia / ventricular fibrillation on EPS [odds ratio (OR) 4; confidence interval (CI) 1.298-12.325; p = 0.028]. After adjustment for other variables such as age, ejection fraction (EF) and QRS size, there was a trend for the abnormal QRS-T angle to identify patients with increased risk of inducing VT / VF during EPS (OR 3.95; CI 0.99-15.82; p = 0.052). The EF also emerged as a predictor of induction of VT / VF: for each point increase in EF, there was a 4% reduction in the rate of sustained ventricular arrhythmia on EPS. Conclusions: Changes in the QRS-T angle and decreases in EF were associated with an increased risk of induction of VT / VF on EPS.Fundamento: O ângulo QRS-T mostra correlação com prognóstico em pacientes com insuficiência cardíaca e doença coronariana, traduzido por um aumento na mortalidade proporcional ao aumento na diferença entre os eixos do complexo QRS e da onda T no plano frontal. Até hoje, nenhuma informação a este respeito foi obtida em pacientes com cardiopatia chagásica. Objetivo: Correlacionar o ângulo QRS-T com a indução de taquicardia ventricular / fibrilação ventricular (TV / FV) em chagásicos durante estudo eletrofisiológico (EEF). Métodos: Estudo caso-controle em centro terciário. Pacientes sem indução de TV / FV ao EEF foram utilizados como controles. O ângulo QRS-T foi categorizado como normal (0-105º), limítrofe (105-135º) e anormal (135-180º). As diferenças entre os grupos foram analisadas pelo teste t ou teste de Mann-Whitney para variáveis contínuas, e teste exato de Fisher ou qui-quadrado para variáveis categóricas. Valores de p < 0,05 foram considerados significativos. Resultados: De 116 pacientes submetidos ao EEF, 37,9% foram excluídos por estarem com dados incompletos / prontuários inativos ou pela impossibilidade de se calcular corretamente o ângulo QRS-T (presença de bloqueio de ramo esquerdo e fibrilação atrial). De 72 pacientes incluídos, 31 induziram TV / FV ao EEF. Destes, o ângulo QRS-T se encontrava normal em 41,9%, limítrofe em 12,9% e anormal em 45,2%. No grupo de pacientes sem indução de TV / FV, o ângulo QRS-T se encontrava normal em 63,4%, limítrofe em 14,6% e anormal em 17,1% (p = 0,04). Quando comparados aos pacientes com ângulo QRS-T normal, o risco de indução de TV / FV nos pacientes com ângulo anormal foi quatro vezes maior [odds ratio (OR) 4; intervalo de confiança (IC) 1,298-12,325; p = 0,028). Após ajuste para outras variáveis como idade, fração de ejeção (FE) e tamanho do QRS, houve tendência do ângulo QRS-T anormal em identificar pacientes com maior risco de indução de TV / FV (OR 3,95; IC 0,99-15,82; p = 0,052). A FE também se evidenciou como preditora de indução de TV / FV: um ponto de aumento na FE reduziu em 4% a taxa de indução de arritmia ventricular sustentada ao EEF. Conclusões: Alterações no ângulo QRS-T e redução na FE estiveram associadas a um aumento no risco de indução de TV / FV ao EEF.
- The Unnatural History of Tetralogy of Fallot: Prospective Follow-Up of 40 Years After Surgical Correction. [JOURNAL ARTICLE]
- Circulation 2014 Oct 23.
-Prospective data on long-term survival and clinical outcome beyond 30 years after surgical correction of Tetralogy of Fallot (ToF) is non-existing.-This longitudinal cohort study consists of the 144 ToF patients who underwent surgical repair at age <15 years between 1968-1980 in our center. They are investigated every ten years. Cumulative survival (data available in 136 patients) was 72% after 40 years. Late mortality was due to heart failure and ventricular fibrillation. Seventy-two of 80 (90%) eligible survivors participated in the third in-hospital investigation, consisting of electrocardiography, Holter, echocardiography, cardiopulmonary exercise testing, NT-proBNP measurement, CMR including dobutamine stress testing and the SF-36 questionnaire. Median follow-up was 36 (range 31-43) years. Cumulative event-free survival was 25% after 40 years. Subjective health status was comparable to the normal Dutch population. Although systolic right and left ventricular function declined, the peak exercise capacity remained stable. There was no progression of aortic root dilation. A prior shunt operation, low temperature during surgery and early postoperative arrhythmias were found to predict late mortality (HR 2.9, 1.1 and 2.5 respectively). Increase in QRS-duration, deterioration of exercise tolerance and ventricular dysfunction did not predict mortality. Insertion of a transannular patch was a predictor for late arrhythmias (HR 4.0 [95%CI 1.2-13.4]).-Although many patients needed a reoperation or developed arrhythmias, late mortality was low and the clinical condition and subjective health status of most patients remained good. Prior shunt, low temperature during surgery and early postoperative arrhythmias were found to predict late mortality.
- Ozone co-exposure modifies cardiac responses to fine and ultrafine ambient particulate matter in mice: concordance of electrocardiogram and mechanical responses. [JOURNAL ARTICLE]
- Part Fibre Toxicol 2014 Oct 16; 11(1):54.
BackgroundStudies have shown a relationship between air pollution and increased risk of cardiovascular morbidity and mortality. Due to the complexity of ambient air pollution composition, recent studies have examined the effects of co-exposure, particularly particulate matter (PM) and gas, to determine whether pollutant interactions alter (e.g. synergistically, antagonistically) the health response. This study examines the independent effects of fine (FCAPs) and ultrafine (UFCAPs) concentrated ambient particles on cardiac function, and determine the impact of ozone (O3) co-exposure on the response. We hypothesized that UFCAPs would cause greater decrement in mechanical function and electrical dysfunction than FCAPs, and that O3 co-exposure would enhance the effects of both particle-types.MethodsConscious/unrestrained radiotelemetered mice were exposed once whole-body to either 190 ¿g/m3 FCAPs or 140 ¿g/m3 UFCAPs with/without 0.3 ppm O3; separate groups were exposed to either filtered air (FA) or O3 alone. Heart rate (HR) and electrocardiogram (ECG) were recorded continuously before, during and after exposure, and cardiac mechanical function was assessed using a Langendorff perfusion preparation 24 hrs post-exposure.ResultsFCAPs alone caused a significant decrease in baseline left ventricular developed pressure (LVDP) and contractility, whereas UFCAPs did not; neither FCAPs nor UFCAPs alone caused any ECG changes. O3 co-exposure with FCAPs caused a significant decrease in heart rate variability when compared to FA but also blocked the decrement in cardiac function. On the other hand, O3 co-exposure with UFCAPs significantly increased QRS-interval, QTc and non-conducted P-wave arrhythmias, and decreased LVDP, rate of contractility and relaxation when compared to controls.ConclusionsThese data suggest that particle size and gaseous interactions may play a role in cardiac function decrements one day after exposure. Although FCAPs¿+¿O3 only altered autonomic balance, UFCAPs¿+¿O3 appeared to be more serious by increasing cardiac arrhythmias and causing mechanical decrements. As such, O3 appears to interact differently with FCAPs and UFCAPs, resulting in varied cardiac changes, which suggests that the cardiovascular effects of particle-gas co-exposures are not simply additive or even generalizable. Additionally, the mode of toxicity underlying this effect may be subtle given none of the exposures described here impaired post-ischemia recovery.
- Long QT Syndrome Complicating Atrio-Ventricular Block: Arrhythmogenic Effects of Cardiac Memory. [JOURNAL ARTICLE]
- Circ Arrhythm Electrophysiol 2014 Oct 13.
-The magnitude of QT-prolongation in response to bradycardia, rather than the bradycardia per-se, determines the risk for torsade-de-pointes (TdP) during atrio-ventricular block (AVB). However, we do not know why some patients develop more QT prolongation than others despite similar bradycardia. We hypothesized that in patients who develop significant QRS-vector changes during AVB, the effects of cardiac memory leads to excessive QT prolongation.-We studied 91 patients who presented with AVB and who also had an ECG predating the bradyarrhythmia for comparison. We correlated changes in QRS-morphology and axis taking place during AVB with the bradycardia-induced QT prolongation. Patients with and without QRS-morphology changes at the time of AVB were of similar age and gender. Moreover, despite similar R-R interval during AVB, cases involving a QRS-morphology change had significantly longer QT (648±84 vs. 561±84, p<0.001) than cases with no QRS-morphology change. Patients who developed a change in QRS morphology at the time of AVB had a 7-fold higher risk of developing long QT. This risk nearly doubled when the change in QRS morphology was accompanied by a change in QRS axis.-Cardiac memory resulting from a change in QRS-morphology during AVB is independently associated with QT prolongation and may be arrhythmogenic during AVB.
- Association of Aminoacyl-tRNA Synthetases Gene Polymorphisms with the Risk of Congenital Heart Disease in the Chinese Han Population. [Journal Article]
- PLoS One 2014; 9(10):e110072.
Aminoacyl-tRNA synthetases (ARSs) are in charge of cellular protein synthesis and have additional domains that function in a versatile manner beyond translation. Eight core ARSs (EPRS, MRS, QRS, RRS, IRS, LRS, KRS, DRS) combined with three nonenzymatic components form a complex known as multisynthetase complex (MSC).We hypothesize that the single-nucleotide polymorphisms (SNPs) of the eight core ARS coding genes might influence the susceptibility of sporadic congenital heart disease (CHD). Thus, we conducted a case-control study of 984 CHD cases and 2953 non-CHD controls in the Chinese Han population to evaluate the associations of 16 potentially functional SNPs within the eight ARS coding genes with the risk of CHD. We observed significant associations with the risk of CHD for rs1061248 [G/A; odds ratio (OR) = 0.90, 95% confidence interval (CI) = 0.81-0.99; P = 3.81×10-2], rs2230301 [A/C; OR = 0.73, 95%CI = 0.60-0.90, P = 3.81×10-2], rs1061160 [G/A; OR = 1.18, 95%CI = 1.06-1.31; P = 3.53×10-3] and rs5030754 [G/A; OR = 1.39, 95%CI = 1.11-1.75; P = 4.47×10-3] of EPRS gene. After multiple comparisons, rs1061248 conferred no predisposition to CHD. Additionally, a combined analysis showed a significant dosage-response effect of CHD risk among individuals carrying the different number of risk alleles (Ptrend = 5.00×10-4). Compared with individuals with "0-2" risk allele, those carrying "3", "4" or "5 or more" risk alleles had a 0.97-, 1.25- or 1.38-fold increased risk of CHD, respectively. These findings indicate that genetic variants of the EPRS gene may influence the individual susceptibility to CHD in the Chinese Han population.
- Left ventricular electrical activation during right ventricular pacing in heart failure patients with LBBB: Visualization by electrocardiographic imaging and implications for cardiac resynchronization therapy. [JOURNAL ARTICLE]
- J Electrocardiol 2014 Sep 16.
Assess effect of right ventricular pacing (RVP) on left ventricular (LV) activation in heart failure patients with left bundle branch block (LBBB).LV activation during RVP is regarded as similar to LBBB; hence novel CRT algorithms may avoid RVP by adopting "fusion" pacing with intrinsic RBB-mediated conduction. However, other CRT techniques demand RV paced wavefronts for optimal resynchronization. Appropriate selection may require attention to interaction between RVP-generated wavefronts with preexisting conduction abnormalities posed by LBBB i.e. transseptal delay and LV activation. We hypothesized that LV activation during RVP would differ to LBBB.Eleven patients (59±19years, 8 male, LV ejection fraction 25±10%; ischemic etiology 45%) were studied 5.4±5months after CRT implant. All had intact AV conduction with LBBB (PR interval 204±55; QRS 167±27ms) prior to CRT. None had mid-septal/outflow tract lead positions. Using non-invasive electrocardiographic imaging (ECGI), LV activation was contrasted in each patient between intrinsic conduction and RVP with minimized AV interval (i.e. committing ventricular excitation to the paced wavefront).RVP affected LV activation variably. Transseptal time decreased in 64% of patients. More LV conduction barriers were created than resolved, slowing LV free wall activation from 67±29ms during intrinsic conduction to 104±24ms with RVP (p=0.025). The load of late-activated LV myocardium increased in 73% but decreased in 27% patients. Changes were not reflected by QRS duration. Ultimate action of RVP in any patient depended on summary effects of transseptal breakthrough and following LV activation. If both were enhanced then LV preexcitation occurred. If one was delayed but other accelerated, then the outcome of their balance determined the ultimate effect on LV depolarization.RVP may aggravate or resolve LBBB-induced conduction problems at one or more levels. Its avoidance vs integration (or timing relative to LV pacing) during CRT depends on its electrical action in any particular individual.