Showing papers on "QRS complex published in 2006"
TL;DR: The fQRS on a 12-lead ECG is a marker of a prior MI, defined by regional perfusion abnormalities, which has a substantially higher sensitivity and negative predictive value compared with the Q wave.
Abstract: Background— Q waves on a 12-lead ECG are markers of a prior myocardial infarction (MI). However, they may regress or even disappear over time, and there is no specific ECG sign of a non–Q-wave MI. Fragmented QRS complexes (fQRSs), which include various RSR′ patterns, without a typical bundle-branch block are markers of altered ventricular depolarization owing to a prior myocardial scar. We postulated that the presence of an fQRS might improve the ability to detect a prior MI compared with Q waves alone by ECG. Methods and Results— A cohort of 479 consecutive patients (mean±SD age, 58.2±13.2 years; 283 males) who were referred for nuclear stress tests was studied. The fQRS included various morphologies of the QRS ( 1 R′ (fragmentation) in 2 contiguous leads, corresponding to a major coronary artery territory. The Q wave was present in 71 (14.8%) patients, an fQRS was present in 191 (34.9%) patients, and an fQRS an...
522 citations
TL;DR: Although clinically underrecognized, idiopathic VT may originate from the perivascular sites on the left ventricular epicardium, which is amenable to ablation by transvenous or transpericardial approaches, although technical challenges remain.
Abstract: Background— Despite the success of catheter ablation for treatment of idiopathic ventricular tachycardia (VT), occasional patients have been reported in whom VT could not be ablated from the right or left ventricular endocardium or from the aortic sinus of Valsalva (ASOV). Methods and Results— In 12 of 138 patients (9%) with idiopathic VT referred for ablation, an epicardial left ventricular site of origin was identified >10 mm from the ASOV. Coronary venous mapping demonstrated epicardial preceding endocardial activation by >10 ms (41±7 versus 15±11 ms before QRS onset; P<0.001). VT induction was facilitated by catecholamines and terminated by adenosine. Ablation through the coronary veins or via percutaneous transpericardial catheterization was successful in 9 patients; 2 required direct surgical ablation as a result of anatomic constraints. No ECG pattern was specific for epicardial VT. However, slowed initial precordial QRS activation, as quantified by a novel metric, the maximum deflection index, was...
344 citations
TL;DR: Cardiac resynchronization therapy for HF patients with narrow QRS complexes and coexisting mechanical asynchrony by TDI results in LV reverse remodeling and improvement of clinical status.
262 citations
TL;DR: Cardiac resynchronization therapy appears to be beneficial in patients with narrow QRScomplex and severe LV dyssynchrony on TDI, with similar improvement in symptoms and comparable LV reverse remodeling to patients with wide QRS complex.
254 citations
TL;DR: Measuring LV lead electrical delay is useful during CRT device implantation because it may help predict hemodynamic response and long-term clinical outcome, and is associated with worse clinical outcome within the entire cohort.
250 citations
TL;DR: The new algorithm devised by incorporating two new criteria was devised and compared with the Brugada criteria and is a highly accurate tool for correctly diagnosing the cause of WCT ECGs.
Abstract: Aims The Brugada criteria proposed to distinguish between regular, monomorphic wide QRS complex tachycardias (WCT) caused by supraventricular (SVT) and ventricular tachycardia (VT) have been reported to have a better sensitivity and specificity than the traditional criteria. By incorporating two new criteria, a new, simplified algorithm was devised and compared with the Brugada criteria.
Methods and results A total of 453 WCTs (331 VTs, 105 SVTs, 17 pre-excited tachycardias) from 287 consecutive patients with a proven electrophysiological (EP) diagnosis were prospectively analysed by two of the authors blinded to the EP diagnosis. The following criteria were analysed: (i) presence of AV dissociation; (ii) presence of an initial R wave in lead aVR; (iii) whether the morphology of the WCT correspond to bundle branch or fascicular block; (iv) estimation of initial ( v i) and terminal ( v t) ventricular activation velocity ratio ( v i/ v t) by measuring the voltage change on the ECG tracing during the initial 40 ms ( v i) and the terminal 40 ms ( v t) of the same bi- or multiphasic QRS complex. A v i/ v t >1 was suggestive of SVT and a v i/ v t ≤1 of VT. An initial R wave in lead aVR suggested VT. The overall test accuracy of the new algorithm was superior ( P = 0.006) to that of the Brugada criteria. The new algorithm had a greater sensitivity ( P < 0.001) and (−) predictive value (NPV) for VT diagnosis, and specificity ( P = 0.0471) and (+) predictive value (PPV) for SVT diagnosis than those of the Brugada criteria [both NPV for VT diagnosis and PPV for SVT diagnosis were: 83.5% (95% confidence interval = CI 75.9–91.1%) for the new vs. 65.2% (95% CI 56.5–73.9%) for the Brugada algorithms].
Conclusion The new algorithm is a highly accurate tool for correctly diagnosing the cause of WCT ECGs.
167 citations
TL;DR: This study compared chronic right ventricular pacing at the septum versus apex to find the best pacing strategy for deep vein thrombosis in patients with RV.
Abstract: OBJECTIVES This study compared chronic right ventricular (RV) pacing at the septum versus apex. BACKGROUND Chronic RV apical pacing may be detrimental to ventricular function. This randomized, pilot study examined whether, compared with apical, permanent septal pacing preserves cardiac function. METHODS Ablation of the atrioventricular junction for permanent AF, followed by implantation of a DDDR pacemaker connected to two ventricular leads was performed in 28 patients. One lead screwed into the septum and another placed at the apex were connected to the atrial and ventricular port, respectively. Septum or apex was paced by programming AAIR or VVIR modes, respectively. Patients were randomly assigned, 4 months later, to pacing at one site for 3 months, and crossed over to the other for 3 months. New York Heart Association class, QRS width and axis, left ventricular ejection fraction (LVEF), exercise duration, and peak oxygen uptake were measured. Results in patients with LVEF > 45% and < or = 45% were compared. RESULTS Septal pacing was associated with shorter QRS (145 +/- 4 msec vs 170 +/- 4 msec, P < 0.01) and normal axis (40 degrees +/- 10 degrees vs -71 +/- 4 degrees , P < 0.01). At 3 months, among patients with baseline LVEF < or = 45%, LVEF was 42 +/- 5% after septal pacing versus 37 +/- 4% after apical pacing (P < 0.001). CONCLUSION In contrast to RV apical pacing, chronic RV septal pacing preserved LVEF in patients with baseline LVEF < or = 45%.
157 citations
TL;DR: Quantitative QRS duration was a significant and independent predictor of cardiovascular mortality in a general medical population and similar in patients with an abnormal electrocardiogram, a bundle branch block, and a paced rhythm.
141 citations
TL;DR: In this paper, the role of Purkinje fibers in post-infarction ventricular tachycardia (VT) was assessed in a group of 81 consecutive patients referred for catheter ablation, 9 patients were identified in whom the clinical VT had a QRS duration ≤145 ms.
134 citations
TL;DR: Both MRI and TDI yield comparable information on LV dyssynchrony; MRI is useful in the selection of patients for CRT.
130 citations
TL;DR: A Q wave or QS in leads that best reflect local activation suggest an epicardial origin for RV depolarization and may help in identifying a probable epicardials site of origin for CVVT in the RV.
TL;DR: AV delay optimization by Doppler echocardiography for patients with severe heart failure treated with a CRT device yields a greater systolic improvement when guided by the aortic VTI method compared with the mitral inflow method.
TL;DR: A case of idiopathic VF that emonstrates J waves is presented and the response of J waves to several gents and pacing is evaluated.
TL;DR: The benefits of CRT on improvement in cardiac function and clinical outcome in young patients that developed congestive heart failure (CHF) and DCM following cardiac pacing for AV block are sought.
Abstract: DCM Following RV Pacing. Introduction: Cardiac resynchronization therapy (CRT) has been demonstrated to result in clinical improvement in older adult patients with dilated cardiomyopathy (DCM), specifically those with left bundle branch block and prolonged QRS duration. We sought to demonstrate the benefits of CRT on improvement in cardiac function and clinical outcome in young patients that developed congestive heart failure (CHF) and DCM following cardiac pacing for AV block. Methods and Results: We reviewed the charts of six patients who developed CHF or low cardiac output symptoms and DCM following implantation of right ventricular (RV)-based pacing systems for AV block, and subsequently underwent CRT. Patients ranged in age from 6 months to 23.7 years (mean: 11.3 ± 3.6 years). AV block was congenital (3), post-surgery (2), and acquired (1). Pacing had been performed for 0.1-14.5 (7.6 ± 2.4) years prior to development of DCM. Two patients required listing for cardiac transplantation. Following CRT: (1) QRS duration shortened from 204 ± 15 to 138 ± 10 msec, P = 0.002, (2) left ventricular ejection fraction improved from 34 ± 6 to 60 ± 2%, P = 0.003, and (3) left ventricular end diastolic dimension shortened from 5.5 ± 0.8 to 4.3 ± 0.5 cm, P =0.03. All patients demonstrated clinical improvement and have been weaned from CHF medications and listing for cardiac transplantation. Conclusions: CRT can benefit young patients that develop CHF and DCM following RV pacing for AV block. Upgrading to biventricular pacing systems should be considered early in the management of these patients prior to listing for cardiac transplantation.
TL;DR: To characterize the pacing site in an unselected series of patients undergoing right ventricular outflow tract (RVOT) lead placement and investigate the role of the electrocardiogram (ECG) in predicting implantation.
Abstract: OBJECTIVE To characterize the pacing site in an unselected series of patients undergoing right ventricular outflow tract (RVOT) lead placement and investigate the role of the electrocardiogram (ECG) in predicting implantation. BACKGROUND Right ventricular apical pacing is associated with long-term adverse effects on left ventricular function, fuelling interest in alternative pacing sites, especially the RVOT. Previous studies have been conflicting, possibly due to poor definition of pacing site within the RVOT. METHODS In 150 patients undergoing pacemaker implantation, implanters were asked to place the lead in the RVOT. Radiographs were performed in the antero-posterior (AP) and 40 degrees right and left anterior-oblique projections post procedure. Fifty-six had left lateral radiographs. Lead position was categorized using AP/RAO (right anterior oblique) to confirm RVOT placement and left anterior oblique to distinguish free wall from septum. A 12-lead ECG was performed during ventricular pacing. RESULTS Leads were below the RVOT in 18. Of the remaining 132, the majority (94%) were in the inferior/low RVOT. Eighty-one out of 132 were septal and 51 free wall. Septal sites were associated with shorter QRS duration (134 ms vs 143 ms, P < 0.02). Free wall sites displayed more frequent notching of the inferior leads (P < 0.01). A negative deflection in lead I provided a positive predictive value of 90% for septal sites. In those with lateral radiographs, a posteriorly projected lead was 100% specific for septal placement. CONCLUSIONS This study demonstrates the heterogeneity of lead placement within the RVOT. Septal and free wall sites display characteristic ECG patterns which may be used to aid placement. The left lateral radiograph is useful in confirming a true septal location.
TL;DR: Patients with chronic HF should undergo ultrasound evaluation to quantify dyssynchrony of LV myocardial deformation, which would help identifying CRT responders, as well as identifyresponders with good accuracy and reproducibility.
Abstract: Aims We tested the hypothesis that dyssynchrony of left ventricular (LV) myocardial deformation evaluated by ultrasound can predict success of cardiac resynchronization therapy (CRT) in patients with heart failure (HF).
Methods and results Thirty-seven patients with dilated cardiomyopathy, New York Heart Association class III–IV, LV ejection fraction (EF) ≤35%, QRS>120 ms were studied before, at pre-discharge, and after 3 and 6 months of CRT. The M-mode peak septal-to-posterior wall motion and thickening delay (SPWMD and SPWTD, ms) and the standard deviation of the averaged time-to-peak strain (TPS-SD, ms) of 12 middle and basal LV segments obtained from the three standard apical views were calculated. Responders were defined at month 6 by ≥20% EF increase and/or ≥15% end-systolic volume (ESV) decrease with respect to baseline. Baseline SPWTD (not SPWMD) and TPS-SD differentiated responders from non-responders with good accuracy and reproducibility. A value ≥194 ms for SPWTD and ≥60 ms for TPS-SD was significantly associated with responder identification. Baseline dyssynchrony parameters correlated significantly with EF ( r =0.53 for SPWTD and r =0.86 for TPS-SD) and ESV variations ( r =−0.42 for SPWTD and r =−0.73 for TPS-SD).
Conclusion Patients with chronic HF should undergo ultrasound evaluation to quantify dyssynchrony of LV myocardial deformation, which would help identifying CRT responders.
TL;DR: This work aimed to establish sensitivity, specificity, and safety of flecainide testing, and to predict a positive test outcome from the baseline ECG.
Abstract: Diagnostic Value of Flecainide Testing. Introduction: Provocation tests with sodium channel blockers are often required to unmask ECG abnormalities in Brugada syndrome (BrS). However, their diagnostic value is only partially established, while life-threatening ventricular arrhythmias during these tests were reported. We aimed to establish sensitivity, specificity, and safety of flecainide testing, and to predict a positive test outcome from the baseline ECG. Methods and Results: We performed 160 tests with flecainide in subjects determined to be at risk for BrS. P wave width, PQ duration, QRS width, S wave amplitude and duration in leads II-III, in addition to ST morphology and J point elevation in V1-V3 were measured before and after flecainide administration. Moreover, leads were positioned over the third intercostal space (V1 IC3 -V2 IC3 ). Flecainide tests were considered positive if criteria from the First Consensus Report on BrS were fulfilled. In 64 cases, the test was positive, while 95 were negative (1 test was prematurely interrupted). The sensitivity and specificity, calculated in SCN5A-positive probands and their family members, were 77% and 80%, respectively. Baseline ECGs exhibited significant group differences in P, PQ, and QRS duration, J point elevation (leads V1-V2 and V1 IC3 -V2 IC3 ), and S duration in II, but an attempt to predict the outcome of flecainide testing from these baseline ECG parameters failed. No malignant arrhythmias were observed. Conclusion: Flecainide testing is a valid and safe tool to identify SCN5A-related BrS patients. Baseline ECGs do not predict test outcomes, but point to conduction slowing as a core mechanism in BrS.
TL;DR: The relationship between QRS width, heart size, intercellular coupling, and CV in a rabbit model of moderate HF and in computer simulations found increased myocyte size combined with the observed expression pattern of connexin43 yields increased &thgr;L and &th Gr;T and unchanged &thGr;™ in the authors' nonischemic model of HF.
Abstract: Background— Patients with heart failure (HF) have an increased QRS duration, usually attributed to decreased conduction velocity (CV) due to ionic remodeling but which may alternatively result from increased heart size or cellular uncoupling. We investigated the relationship between QRS width, heart size, intercellular coupling, and CV in a rabbit model of moderate HF and in computer simulations. Methods and Results— HF was induced by pressure-volume overload. Heart weight (21.1±0.5 versus 10.2±0.4 g, mean±SEM; P<0.01) and QRS duration (58±1 versus 50±1 ms; P<0.01) were increased in HF versus control. Longitudinal CV (θL; 79±2 versus 67±4 cm/s; P<0.01) and transversal subepicardial CV (θT; 43±2 versus 37±2 cm/s; P<0.05) were higher in HF than in controls. Transmural CV (θTM) was unchanged (25±2 versus 24±1 cm/s; P=NS). Patch-clamp experiments demonstrated that sodium current was unchanged in HF versus control. Immunohistochemical experiments revealed that connexin43 content was reduced in midmyocardium bu...
TL;DR: In this community-based sample, longer electrocardiographic QRS was associated with increasedCHF risk, consistent with the hypothesis that depolarization delay may increase CHF risk.
Abstract: Prolonged electrocardiographic QRS duration is frequently observed in congestive heart failure (CHF) patients. We hypothesized that CHF risk increases with longer QRS interval in individuals free o...
TL;DR: The safety and efficacy of CRT in patients with ALVD or mild HF and electrocardiographic evidence of ventricular dyssynchrony are assessed.
TL;DR: In this paper, a meta-analysis of randomized controlled trials was conducted to evaluate the effect of left ventricular pacing (LV) in heart failure patients with LBBB, QRS >130 milliseconds, New York Heart Association class.
TL;DR: Improvements in LV global function, dyssynchrony variables and symptoms in patients chronically paced from the RV that are similar to those observed in patients with LBBB without preexisting devices are suggested.
TL;DR: Reentrant monomorphic VT originating from the left posterior Purkinje fibers, which is analogous to idiopathic left VT, can develop in the acute or chronic phase of MI.
TL;DR: Reference values for the duration and/or amplitude of some ECG parameters both in terms of means and variability over the recording period are established and the influence of body position, genetic strain and HR on theECG parameters are evaluated.
Abstract: The aim of the study was to establish a database for electrocardiographic parameters of Beagle dogs used for toxicological studies and to evaluate the influence of supplier, sex, heart rate (HR) and body position for electrocardiogram (ECG) recording on ECG parameters. Peripheral ECG leads were recorded from 934 female and 946 male dogs from Marshall Farms and 27 females and 30 males from Harlan, either standing on a table or restrained in a hammock. HR, RR, PQ and QT intervals, P and QRS duration and P-wave amplitude were measured. There were no major differences between sexes for ECG parameters. The axis of the heart was shifted to the left when the animals were restrained in a hammock compared to when they were standing on a table. The PQ interval was higher (about 9%) in Harlan than in Marshall dogs. HR was negatively correlated with QT (coefficient of linear correlation: r=-0.61 to -0.74), which emphasizes the need for a formula correcting QT interval for HR when interpreting changes in QT interval. HR was also negatively correlated with PQ intervals (r=-0.26 to -0.11), whereas a positive correlation was found between HR and the amplitude of the P wave (r=0.21-0.34). The level of the respiratory sinus arrhythmia (SA) was quantified by calculating the ratio of maximum to minimum RR interval measured over a 10 s period. This ratio was negatively correlated with HR (r =-0.49 to -0.33). Therefore, at high HRs, SA was less marked than at low HRs, but it did not completely disappear. Analysis of beat-to-beat variation indicated that QT and PQ intervals and the amplitude of P wave fluctuated over time and the degree of this variability was positively correlated with the level of SA. In conclusion, we have established reference values for the duration and/or amplitude of some ECG parameters both in terms of means and variability over the recording period, and we have evaluated the influence of body position, genetic strain and HR on the ECG parameters. These data can be used as baseline for the interpretation of the ECG of Beagle dogs.
TL;DR: Daily fluctuations in 12‐lead electrocardiogram and signal‐averaged ECG characteristics between symptomatic and asymptomatic patients with Brugada syndrome are compared to identify new markers for distinguishing between high‐ and low‐risk patients.
Abstract: Daily Fluctuations of ECG in Brugada Syndrome. Introduction: Risk stratification between symptomatic and asymptomatic patients with Brugada syndrome is not yet established. We compared daily fluctuations in 12-lead electrocardiogram (ECG) and signal-averaged ECG (SAECG) characteristics between symptomatic and asymptomatic patients with Brugada syndrome to identify new markers for distinguishing between high- and low-risk patients. Methods and Results: Thirty-five patients with Brugada syndrome underwent ECG and SAECG simultaneously at least 4 times every 3 months. We evaluated daily fluctuations (differences between maximum and minimum values) in ECG and SAECG characteristics and compared them between symptomatic (N = 11), and asymptomatic (N = 24) patients. On ECG, the daily fluctuations in r-J interval (interval from QRS onset to J point) in leads VI, V2, and V6 were significantly larger in symptomatic than in asymptomatic patients (VI; 20 ± 6 vs 10 ± 8 msec, P < 0.01, V2; 22 ± 8 vs 11 ± 4 msec, P < 0.01, and V6; 24 ± 7 vs 14 ± 7 msec, P < 0.01). On SAECG, daily fluctuations in filtered QRS (f-QRS) duration and LAS40 were significantly larger in symptomatic than in asymptomatic patients (f-QRS; 15 ± 7 vs 9 ± 4 msec, P < 0.05, and LAS40; 21 ± 7 vs 10 ± 6 msec, P < 0.05). Conclusions: Instability of depolarization appears to be related to the risk of fatal ventricular arrhythmias in patients with Brugada syndrome. Daily fluctuations in ECG and SAECG characteristics could be useful for distinguishing between high- and low-risk patients with Brugada syndrome.
TL;DR: An algorithm combining lead I QRS duration for sensitivity and axis for specificity is useful for differentiating the two tachycardia substrates.
TL;DR: The aim of this study was to draw up a set of easy criteria to differentiate and validate the two kinds of stimulations according to the pacing output and the ECG/EKG signals.
Abstract: Background: His Bundle (HB) pacing is a valid alternative to right ventricular pacing for patients with preserved His-ventricle conduction who are candidates for permanent stimulation. Permanent pacing in the HB area enables Selective HB pacing (SHBP) or para-Hisian pacing (PHP) to be achieved. The aim of our study was to draw up a set of easy criteria to differentiate and validate the two kinds of stimulations according to the pacing output and the ECG/EKG signals.
Methods and Results: From February to July 2005, 17 patients eligible for a pacemaker (PM) procedure underwent implantation with the Medtronic SelectSecure® lead (Medtronic, Minneapolis, MN, USA) screwed into the HB area.SHBP was defined when the intrinsic QRS was equal, in both duration and morphology, to the paced QRS, the His-Ventricular (H-V) interval was equal to Pace-Ventricular interval (Vp-V) and, at low output, only the HB was captured, while increasing the output resulted in both the HB and right ventricular (RV) being captured (widening of QRS at high output). Conversely, PHP was defined when the intrinsic QRS differed from the paced one, either in morphology or in duration and, at high output, both the RV and HB were captured (non-SHBP), while decreasing the output resulted in losing HB capture (widening of QRS at low output). According to these criteria, SHBP was achieved in 11 patients, while in the remaining 6, PHP was obtained. No adverse events were reported.
Conclusions: The above criteria enabled SHBP and PHP to be validated easily and clearly. A longer follow-up will be needed in order to ascertain whether the clinical outcome of these two approaches differs.
TL;DR: In patients with anterior AMI and R BBB, increasing QRS duration is associated with increasing 30-day mortality, and early ST-segment resolution after fibrinolytic therapy despite persisting RBBB isassociated with lower mortality rate.
Abstract: Background— Patients with an acute anterior ST-segment elevation myocardial infarction and right bundle-branch block (RBBB) have a high mortality risk, which may be stratified by early ECG changes. Methods and Results— In the Hirulog Early Reperfusion Occlusion (HERO-2) trial, 17 073 patients with acute myocardial infarction (AMI) within 6 hours of symptom onset were treated with streptokinase and randomized to receive bivalirudin or heparin. There was no difference in the primary end point of 30-day mortality. ECGs were recorded at randomization and 60 minutes after fibrinolytic therapy was begun. The 30-day mortality rate was 31.6% in the 415 patients with RBBB and anterior AMI at randomization and 33% in the 100 patients who developed new RBBB at 60 minutes from normal baseline conduction accompanying an anterior AMI. An increase in QRS duration by 20-ms increments was associated with increasing 30-day mortality rate in both RBBB groups on multivariable analyses with covariates of age, Killip class, sy...
TL;DR: Anatomic repair of congenitally corrected transposition of the great arteries can be performed with low operative mortality, however, late left ventricular dysfunction is not uncommon, with higher incidence in those requiring pacing and with a prolonged QRS.
TL;DR: The best predictors of increased short-term mortality are ventricular tachycardia and ST-segment deviations, while electrocardiographic markers of poor outcome that were not independent risk factors on multivariate analysis, conflicting findings, and knowledge gaps are discussed.