Showing papers on "QRS complex published in 2003"
TL;DR: Cardiac resynchronization improved quality of life, functional status, and exercise capacity in patients with moderate to severe HF, a wide QRS interval, and life-threatening arrhythmias without proarrhythmia or compromised ICD function.
Abstract: ContextCardiac resynchronization therapy (CRT) through biventricular pacing
is an effective treatment for heart failure (HF) with a wide QRS; however,
the outcomes of patients requiring CRT and implantable cardioverter defibrillator
(ICD) therapy are unknown.ObjectiveTo examine the efficacy and safety of combined CRT and ICD therapy in
patients with New York Heart Association (NYHA) class III or IV congestive
HF despite appropriate medical management.Design, Setting, and ParticipantsRandomized, double-blind, parallel-controlled trial conducted from October
1, 1999, to August 31, 2001, of 369 patients with left ventricular ejection
fraction of 35% or less, QRS duration of 130 ms, at high risk of life-threatening
ventricular arrhythmias, and in NYHA class III (n = 328) or IV (n = 41) despite
optimized medical treatment.InterventionsOf 369 randomized patients who received devices with combined CRT and
ICD capabilities, 182 were controls (ICD activated, CRT off) and 187 were
in the CRT group (ICD activated, CRT on).Main Outcome MeasuresThe primary double-blind study end points were changes between baseline
and 6 months in quality of life, functional class, and distance covered during
a 6-minute walk. Additional outcome measures included changes in exercise
capacity, plasma neurohormones, left ventricular function, and overall HF
status. Survival, incidence of ventricular arrhythmias, and rates of hospitalization
were also compared.ResultsAt 6 months, patients assigned to CRT had a greater improvement in median
(95% confidence interval) quality of life score (–17.5 [–21 to
–14] vs –11.0 [–16 to –7], P =
.02) and functional class (–1 [–1 to –1] vs 0 [–1
to 0], P = .007) than controls but were no different
in the change in distance walked in 6 minutes (55 m [44-79] vs 53 m [43-75], P = .36). Peak oxygen consumption increased by 1.1 mL/kg
per minute (0.7-1.6) in the CRT group vs 0.1 mL/kg per minute (–0.1
to 0.8) in controls (P = .04), although treadmill
exercise duration increased by 56 seconds (30-79) in the CRT group and decreased
by 11 seconds (–55 to 12) in controls (P<.001).
No significant differences were observed in changes in left ventricular size
or function, overall HF status, survival, and rates of hospitalization. No
proarrhythmia was observed and arrhythmia termination capabilities were not
impaired.ConclusionsCardiac resynchronization improved quality of life, functional status,
and exercise capacity in patients with moderate to severe HF, a wide QRS interval,
and life-threatening arrhythmias. These improvements occurred in the context
of underlying appropriate medical management without proarrhythmia or compromised
ICD function.
1,609 citations
TL;DR: Ventricular desynchronization imposed by ventricular pacing even when AV synchrony is preserved increases the risk of HF hospitalization and AF in SND with normal baseline QRSd.
Abstract: Background— Dual-chamber (DDDR) pacing preserves AV synchrony and may reduce heart failure (HF) and atrial fibrillation (AF) compared with ventricular (VVIR) pacing in sinus node dysfunction (SND). However, DDDR pacing often results in prolonged QRS durations (QRSd) as the result of right ventricular stimulation, and ventricular desynchronization may result. The effect of pacing-induced ventricular desynchronization in patients with normal baseline QRSd is unknown. Methods and Results— Baseline QRSd was obtained from 12-lead ECGs before pacemaker implantation in MOST, a 2010-patient, 6-year, randomized trial of DDDR versus VVIR pacing in SND. Cumulative percent ventricular paced (Cum%VP) was determined from stored pacemaker data. Baseline QRSd <120 ms was observed in 1339 patients (707 DDDR, 632 VVIR). Cum%VP was greater in DDDR versus VVIR (90% versus 58%, P=0.001). Cox models demonstrated that the time-dependent covariate Cum%VP was a strong predictor of HF hospitalization in DDDR (hazard ratio [HR], 2....
1,505 citations
TL;DR: Responses of LV reverse remodeling were associated with improvement in clinical status, cardiac function, and systolic synchronicity, and when all the above factors were put into univariate and multivariate analyses models, syStolic dyssynchrony was the only independent predictor ofreverse remodeling.
Abstract: Biventricular pacing results in left ventricular (LV) reverse remodeling in heart failure patients with wide QRS complexes. This study examines potential predictors of reverse remodeling. Echocardiography with tissue Doppler imaging was performed at baseline and 3 months after biventricular pacing in 30 patients (21 men and 9 women, mean age 62 +/- 14 years). There were 17 responders to reverse remodeling (defined as a reduction in LV end-systolic volume by >15%) and 13 nonresponders. Responders had significant improvement in 6-minute hall-walking distance (p = 0.006), metabolic equivalents (p = 0.02), peak oxygen uptake (p = 0.02), New York Heart Association functional class (p <0.001), and quality of life (p <0.001); an increase in the sphericity index (p = 0.007), ejection fraction (p <0.001), and diastolic filling time (p = 0.03); a decrease in myocardial performance index (p = 0.02), isovolumic relaxation time (p = 0.004), and mitral regurgitation (p = 0.007); and an improvement in systolic dyssynchrony (SD of the time to peak myocardial systolic contraction of the 12 LV segments as dyssynchrony index) (45.0 +/- 8.3 vs 32.5 +/- 14.5 ms, p = 0.003). In contrast, nonresponders only had a small degree of clinical improvement in New York Heart Association class (p = 0.03) and quality-of-life scores (p = 0.03), without any change in cardiac function, and worsening of systolic dyssynchrony (24.8 +/- 4.5 vs 34.1 +/- 13.5 ms, p = 0.02). When all the above factors were put into univariate and multivariate analyses models, systolic dyssynchrony was the only independent predictor of reverse remodeling (r = -0.76, p <0.001) (beta = -1.54, p = 0.007). A preimplant dyssynchrony index of 32.6 ms (+2 SDs from mean of 88 normal controls) was able to totally segregate responders from nonresponders of biventricular pacing. Thus, responders of LV reverse remodeling were associated with improvement in clinical status, cardiac function, and systolic synchronicity. Direct assessment of systolic synchronicity by tissue Doppler imaging is highly accurate in predicting responders to therapy.
665 citations
TL;DR: In this article, the authors studied the possible occurrence of left ventricular (LV) systolic and diastolic asynchrony in patients with Systolic heart failure (HF) and narrow QRS complexes.
Abstract: Objective: To study the possible occurrence of left ventricular (LV) systolic and diastolic asynchrony in patients with systolic heart failure (HF) and narrow QRS complexes. Design: Prospective study. Setting: University teaching hospital. Patients: 200 subjects were studied by echocardiography. 67 patients had HF and narrow QRS complexes (≤ 120 ms), 45 patients had HF and wide QRS complexes (> 120 ms), and 88 served as normal controls. Interventions: Echocardiography with tissue Doppler imaging was performed using a six basal, six mid-segmental model. Main outcome measures: Severity and prevalence of systolic and diastolic asynchrony, as assessed by the maximal difference in time to peak myocardial systolic contraction (T S ) and early diastolic relaxation (T E ), and the standard deviation of T S (T S -SD) and of T E (T E -SD) of the 12 LV segments. Results: The mean (SD) maximal difference in T S (controls 53 (23) ms v narrow QRS 107 (54) ms v wide QRS 130 (51) ms, both p v controls) and in T S -SD (controls 17.0 (7.8) ms v narrow QRS 33.8 (16.9) ms v wide QRS 42.0 (16.5) ms, both p v controls) was prolonged in the narrow QRS group compared with normal controls. Similarly, the maximal difference in T E (controls 59 (19) ms v narrow QRS 104 (71) ms v wide QRS 148 (87) ms, both p v controls) and in T E -SD (controls 18.5 (5.8) ms v narrow QRS 33.3 (27.7) ms v wide QRS 48.6 (30.2) ms, both p v controls) was prolonged in the narrow QRS group. The prevalence of systolic and diastolic asynchrony was 51% and 46%, respectively, in the narrow QRS group, and 73% and 69%, respectively, in the wide QRS group. Stepwise multiple regression analysis showed that a low mean myocardial systolic velocity from the six basal LV segments and a large LV end systolic diameter were independent predictors of systolic asynchrony, while a low mean myocardial early diastolic velocity and QRS complex duration were independent predictors of diastolic asynchrony. Conclusions: LV systolic and diastolic mechanical asynchrony is common in patients with HF with narrow QRS complexes. As QRS complex duration is not a determinant of systolic asynchrony, it implies that assessment of intraventricular synchronicity is probably more important than QRS duration in considering cardiac resynchronisation treatment.
635 citations
TL;DR: Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes and can be eliminated by focal radiofrequency ablation.
Abstract: Background— The long-QT and Brugada syndromes are important substrates of malignant ventricular arrhythmia. The feasibility of mapping and ablation of ventricular arrhythmias in these conditions has not been reported. Methods and Results— Seven patients (4 men; age, 38±7 years; 4 with long-QT and 3 with Brugada syndrome) with episodes of ventricular fibrillation or polymorphic ventricular tachycardia and frequent isolated or repetitive premature beats were studied. These premature beats were observed to trigger ventricular arrhythmias and were localized by mapping the earliest endocardial activity. In 4 patients, premature beats originated from the peripheral right (1 Brugada) or left (3 long-QT) Purkinje conducting system and were associated with variable Purkinje-to-muscle conduction times (30 to 110 ms). In the remaining 3 patients, premature beats originated from the right ventricular outflow tract, being 25 to 40 ms ahead of the QRS. The accuracy of mapping was confirmed by acute elimination of prema...
473 citations
TL;DR: Cardiac resynchronization therapy may be helpful in patients with echocardiographic evidence of interventricular and intraventricular asynchrony and incomplete left bundle branch block, as well as wide or "narrow" QRS.
373 citations
TL;DR: The rationale for and mechanisms of cardiac resynchronization therapy in heart failure are reviewed as background to a more in-depth discussion of landmark clinical trials.
Abstract: The weight of evidence supporting the routine use of cardiac resynchronization therapy, or atrial-synchronized biventricular pacing, as a treatment for patients with moderate-to-severe chronic systolic heart failure and ventricular dyssynchrony is now quite substantial. Results from mechanistic studies, observational evaluations, and randomized, controlled trials have consistently demonstrated significant improvement in quality of life, functional status, and exercise capacity in patients with New York Heart Association (NYHA) class III and IV heart failure who are assigned to active resynchronization therapy. 1–3 In these patients, cardiac resynchronization has also been shown to improve cardiac structure and function while significantly reducing the risk of worsening heart failure. 1,2 In 2001, the first resynchronization device became commercially available in the United States. The following year, 2 devices that combine biventricular pacing capability with implantable cardioverter defibrillators (ICDs) were approved for use by the US Food and Drug Administration. Recently updated ACC/AHA/ NASPE Pacemaker and ICD Guidelines included cardiac resynchronization therapy as a class IIA recommendation for pacing. 4 Since that time, preliminary results from another large-scale trial have suggested a significant reduction in the combined end point of all-cause mortality and all-cause hospitalization with cardiac resynchronization therapy in an advanced heart failure population. 5 The present article briefly reviews the rationale for and mechanisms of cardiac resynchronization therapy in heart failure as background to a more in-depth discussion of landmark clinical trials. Patient selection and limitations/pitfalls of resynchronization therapy are also discussed. Rationale for Cardiac Resynchronization Therapy Approximately one third of patients with systolic heart failure have a QRS duration greater than 120 ms, which is most commonly seen as left bundle-branch block (LBBB).6,7 In LBBB, the left ventricle is activated belatedly through the septum from the right ventricle, resulting in a significant delay between the onset of left ventricular (LV) and right ventricular contraction. 8,9 Activation of the anterior septum
346 citations
TL;DR: Incessant ventricular tachyarrhythmias after MI may be triggered by VPBs and RF ablation of the triggering VPBs is feasible and can prevent drug-resistant electrical storm, even after acute MI.
Abstract: Background— We report on 4 patients (aged 57 to 77 years; 3 men) who developed drug-refractory, repetitive ventricular tachyarrhythmias after acute myocardial infarction (MI). All episodes of ventricular arrhythmias were triggered by monomorphic ventricular premature beats (VPBs) with a right bundle-branch block morphology (RBBB). Methods and Results— Left ventricular (LV) mapping was performed to attempt radiofrequency (RF) ablation of the triggering VPBs. Activation mapping of the clinical VPBs demonstrated the earliest activation in the anteromedial LV in 1 patient and in the inferomedial LV in 2 patients. Short, high-frequency, low-amplitude potentials were recorded that preceded the onset of each extrasystole by a maximum of 126 to 160 ms. At the same site, a Purkinje potential was documented that preceded the onset of the QRS complex by 23 to 26 ms during sinus rhythm. In 1 patient, only pace mapping was attempted to identify areas of interest in the LV. Six to 30 RF applications abolished all local...
289 citations
TL;DR: The common arrhythmia risk variables, particularly the autonomic and standard ECG markers, have limited predictive power in identifying patients at risk of SCD after AMI in the beta-blocking era.
266 citations
TL;DR: An ECG algorithm is developed to predict the origin of OT‐VT and the accuracy of the algorithm is tested prospectively to test prospectively the accuracyof the algorithm.
Abstract: Introduction: Idiopathic ventricular outflow tract tachycardia or premature ventricular contractions (OT-VTs) can originate from several different sites in the outflow tract, including the left ventricular (LV) endocardium and epicardium. The aims of this study were (1) to develop an ECG algorithm to predict the origin of OT-VT and (2) to test prospectively the accuracy of the algorithm.
Methods and Results: An algorithm was developed by correlating the 12-lead ECG findings with the catheter ablation site in 80 patients with OT-VT. The ECG characteristics of the QRS complex during the arrhythmia were analyzed. The catheter sites were verified by multiplane fluoroscopy. The outflow tract was classified into six subdivisions: right ventricular (RV) septum, RV free wall, RV near the His-bundle region, LV endocardium, left sinus of Valsalva (LSV), and LV epicardium remote from the LSV. An OT-VT originating from the LV epicardium remote from the LSV was defined as an OT-VT in which the earliest ventricular activation was recorded at the LSV and radiofrequency ablation from the LSV failed. This algorithm subsequently was tested prospectively in 88 patients. Overall sensitivity was 88% and specificity was 95%. The positive and negative predictive values were 88% and 96%, respectively.
Conclusion: We describe a new ECG algorithm having a high sensitivity and specificity to identify the optimal ablation site for idiopathic ventricular outflow tachycardia or premature ventricular contractions. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1280-1286, December 2003)
263 citations
TL;DR: It is hypothesized that unique ECG morphologies of pace maps from septal and free‐wall sites in the superior RVOT could be identified using magnetic electroanatomic mapping for accurate anatomical localization and this ECG information could help facilitate pace mapping and accurate VT localization.
Abstract: ECG Patterns of RVOT Tachycardias. Introduction: The superior right ventricular outflow tract (RVOT) septum and free wall are common locations of origin for outflow tract ventricular tachycardias (VT). We hypothesized that (1) unique ECG morphologies of pace maps from septal and free-wall sites in the superior RVOT could be identified using magnetic electroanatomic mapping for accurate anatomical localization; and (2) this ECG information could help facilitate pace mapping and accurate VT localization.
Methods and Results: In 14 patients with structurally normal hearts who were undergoing ablation for outflow tract VT, a detailed magnetic electroanatomic map of RVOT was constructed in sinus rhythm, then pace mapping was performed from anterior, mid, and posterior sites along the septum and free wall of the superior RVOT. Pace maps were analyzed for ECG morphologies in limb leads and transition patterns in precordial leads. Monophasic R waves in inferior leads for septal sites were taller (1.7 ± 0.4 mVvs1.1 ± 0.3 mV; P < 0.01) and narrower (158 ± 21 msecvs168 ± 15 msec; P < 0.01) compared with free-wall sites; lacked “notching” (28.6% vs 95.2%;P < 0.05); and showed early precordial transition (by lead V4; 78.6% vs 4.8%;P < 0.05). A positive R wave in lead I also distinguished posterior from anterior septal and free-wall sites. Based on QRS morphology in limb leads and precordial transition pattern (early vs late), in a retrospective analysis, a blinded reviewer was able to accurately localize the site of origin of clinical arrhythmia (the successful ablation site on the magnetic electroanatomic map) in 25 of 28 patients (90%) with superior RVOT VT.
Conclusion: Pace maps in the superior RVOT region manifest site-dependent ECG morphologies that can help in differentiating free-wall from septal locations and posterior from anterior locations. Despite overlap in QRS amplitude and duration, in the majority of patients a combination of ECG features can serve as a useful template in predicting accurately the site of origin of clinical arrhythmias arising from this region.
TL;DR: The diagnostic dilemma in arrhythmogenic right ventricular dysplasia‐cardiomyopathy (ARVD/C) is that a single diagnostic test does not exist and that there is a need for broadening diagnostic criteria, and ECG data should be revisited.
Abstract: Background: The diagnostic dilemma in arrhythmogenic right ventricular dysplasia-cardiomyopathy (ARVD/C) is that a single diagnostic test does not exist and that there is a need for broadening diagnostic criteria. As standard ECG contributes significantly to clinical diagnosis and represents a tool for screening in family studies ECG data should be revisited.
Methods and Results: In a cohort of 265 patients (159 males, mean age 46.8 years) with ISFC/ESC criteria of ARVD/C ECG features were reevaluated.
QRS duration in (V1 + V2 + V3)/(V4 + V5 + V6) ≥ 1.2—called localized right precordial QRS prolongation—was present in 261/265 patients (98%) and represents the essential finding. Right precordial epsilon potentials were found in 23% in standard and in 75% in highly amplified and modified recording technique. Right precordial T wave inversions were present in 143 cases (54%) and ST-segment elevation of different types in 66 patients (25%). Localized prolongation of inferior QRS complexes could be found in 58 cases (22%), complete right bundle branch block with T inversions beyond V2 in most cases in 17 patients (6%), incomplete right bundle branch block in 38 cases (14%), pseudo-incomplete right bundle branch block in 8 patients (3%), and right precordial R wave reduction in 14 cases (5%).
Conclusion: With regard to sensitivity and already known specificity an ECG score for the diagnosis of ARVD/C was developed with high probability of ARVD/C in cases with ≥4 points, possibly without the need for an additional imaging technique.
Standard ECG with additional highly amplified and modified recording technique represents a single diagnostic test with high value in the clinical diagnosis of ARVD/C and should be used as a first line tool in noninvasive family screening. A.N.E. 2003; 8(3):238-245
TL;DR: EDP measurements appear to identify potential candidates for CRT, and to confirm the success of system implantation, according to recipients of de novo CRT systems and patients with previously implanted standard pacing systems upgraded with the implantation of a left ventricular lead.
Abstract: Multisite biventricular pacing therapy offers significant clinical improvement in some stimulated patients with electrocardiographic criteria of cardiac dyssynchrony. However, observational data increasingly suggest that patients suffering from congestive heart failure in presence of modest QRS widening may also derive benefit from cardiac resynchronization therapy (CRT), and that some patients can be significantly improved clinically after system implantation despite no apparent change in QRS width. This pilot study explored the value of an echocardiographic model to identify cardiac electromechanical dyssynchrony parameters (EDP) in candidates for CRT, and their potential correction after implantation. The study included 66 consecutive CRT recipients of CRT in NYHA functional class III or IV who had one or more atrioventricular, interventricular or intraventricular dyssynchrony criteria. An immediate improvement was observed in 85% of the population with a partial or total correction of their EDP. However, the modifications in EDP differed considerably between recipients of de novo CRT systems and patients with previously implanted standard pacing systems upgraded with the implantation of a left ventricular lead. EDP measurements appear to identify potential candidates for CRT, and to confirm the success of system implantation.
01 Jan 2003
TL;DR: This paper presents a novel algorithm to detect onset and duration of QRS complexes by a transform in which a nonlinear scaling factor is introduced to enhance the QRS complex and to suppress unwanted noise.
Abstract: This paper presents a novel algorithm to detect onset and duration of QRS complexes. After low-pass filtering, the ECG signal is converted to a curve length signal by a transform in which a nonlinear scaling factor is introduced to enhance the QRS complex and to suppress unwanted noise. Adaptive thresholds are applied to the length signal to determine the onset and duration of the QRS complex. The algorithm was evaluated with the complete set of single channel ECGs (signal O) from the MIT-BlH Arrhythmia Database, and achieved a gross QRS sensitivity of 99.65% and a gross QRS positive predictive accuracy of 99.77%. The QRS onset determination is very stable and is insensitive to QRS morphology change. The noise tolerance of the algorithm was evaluated using the MIT-BIH Noise Stress Test Database. The C source code for the single-channel algorithm has been contributed to PhysioToolkit and is freely available from PhysioNet (www.physionet.org).
Journal Article•
TL;DR: Biventricular and left ventricular resynchronization pacing therapies acutely improve systolic ventricular function and energetic efficiency in patients with heart failure and left-bundle-type intraventricular conduction delay.
Abstract: Patients with dilated cardiomyopathy and discoordinate wall motion due to intraventricular conduction delay are at increased risk for exacerbated pump failure and arrhythmias and suffer higher mortality rates. Biventricular and left ventricular resynchronization pacing therapies acutely improve systolic ventricular function and energetic efficiency in patients with heart failure and left-bundle‐type intraventricular conduction delay. Sustained therapy can further inhibit or reverse chronic chamber dilation and remodeling. As with all therapies for heart failure, individual subject responses are variable; however, the invasive nature and expense of resynchronization therapy has particularly highlighted the need to prospectively identify optimal candidates. Although QRS duration has been principally used to date, increasing evidence shows this to have poor acute and chronic correlations with patient response. In contrast, direct measures of mechanical dyssynchrony based on simple echo imaging and more complex tissue Doppler and magnetic resonance imaging‐based approaches appear to afford better predictive accuracy. [Rev Cardiovasc Med. 2003;4(suppl 2):S3‐S13]
TL;DR: Left ventricular function was maintained at SR level during LV septal, LV apex, and multisite pacing, was moderately depressed during pacing at epicardial LV free wall sites, and was most severely depressed during RV apex pacing.
TL;DR: This data indicates that the septal activation pattern in patients with heart failure and left bundle branch block (LBBB‐HF) is regulated by the EMT alone or in combination with other mechanisms.
Abstract: Septal Activation in Patients with LBBB and Heart Failure.Introduction: Little is known about the septal activation pattern in patients with heart failure and left bundle branch block (LBBB-HF).
Methods and Results: The right ventricular (RV) and left ventricular (LV) activation patterns of 12 patients (mean age 67 ± 11 years) with LBBB-HF and 5 patients (mean age 45 ± 14) with normal hearts were studied during sinus rhythm using a three-dimensional mapping system. The etiology of HF was myocardial infarction (n = 4) or idiopathic dilated cardiomyopathy (n = 8). In patients with LBBB-HF, endocardial activation usually started before the onset of the surface QRS complex on the RV free wall. Latest RV activation occurred in the basal region, and total RV activation time was longer than in patients with normal hearts. In patients with LBBB-HF, the left septum was activated via slowly conducting LBB or via right-to-left transseptal conduction. In both patients with LBBB-HF and those with normal hearts, latest LV activation occurred either in the posterior or posterolateral-basal region. Conduction velocity was slower in the peri-scar region, in patients with previous myocardial infarct and globally slow, in patients with idiopathic dilated cardiomyopathy.
Conclusion: The two types of left septal activation observed in patients with LBBB-HF may have consequences for biventricular hemodynamic performance. Conduction slowing along the LV, regionally or globally, suggests a contribution outside the specific conduction system in the ECG pattern of LBBB. (J Cardiovasc Electrophysiol, Vol. 14, pp. 135-141, February 2003)
TL;DR: In this article, a corrected heart rate-corrected QT interval (JTc) was defined as QTc−QRSd using data from the Atherosclerosis Risk in Communities Study.
Abstract: Background— Heart rate-corrected QT interval (QTc) is the traditional method of assessing the duration of repolarization Prolonged heart rate-corrected QT interval is associated with higher risk of mortality in patients with coronary heart disease (CHD) and in the general population However, the QTc is typically not evaluated when QRS duration is ≥120 ms, because increased QRS duration (QRSd) contributes to QT interval prolongation In these circumstances, the JT interval has been proposed as a more valid way to assess ventricular repolarization Methods and Results— To allow for variation in heart rate, corrected JT interval (JTc) was defined as QTc−QRSd Using data from the Atherosclerosis Risk in Communities Study, JTc and QTc were compared for their prognostic associations with incident CHD events among 14 696 men and women who were CHD-free at baseline, having either normal conduction or wide QRS complex Among individuals with normal QRS duration, logistic regression adjusted for age, hypertensive
TL;DR: Electrocardiographic QTd and echocardiographic LV end‐systolic dimension were the most important mortality predictors in patients with Chagas' disease.
Abstract: Background— QT interval parameters are potential prognostic markers of arrhythmogenicity risk and cardiovascular mortality and have never been evaluated in Chagas’ disease. Methods and Results— Outpatients (738) in the chronic phase of Chagas’ disease were enrolled in a long-term follow-up study. Maximal heart rate-corrected QT (QTc) and T-wave peak-to-end (TpTe) intervals and QRS, QT, JT, QTapex, and TpTe dispersions and variation coefficients were measured manually and calculated from 12-lead ECGs obtained on admission. Clinical, radiological, and 2-dimensional echocardiographic data were also recorded. Primary end points were all-cause, Chagas’ disease-related, and sudden cardiac mortalities. During a follow-up of 58±39 months, 62 patients died, 54 of Chagas’ disease-related causes and 40 suddenly. Multivariate Cox survival analysis revealed that the QT-interval dispersion (QTd) (hazard ratio, 1.45; 95% confidence interval, 1.29 to 1.63; P<0.001, for 10-ms increments) and left ventricular (LV) end-syst...
TL;DR: Multisite ventricular pacing results in improved cardiac index and increased systolic blood pressure, and it can also facilitate weaning from cardiopulmonary bypass.
TL;DR: Robotic LV lead placement is an effective and novel technique which can be used for ventricular resynchronization therapy in patients with no other minimally invasive options for biventricular pacing.
TL;DR: In this paper, the authors found that patients with increased QRS duration receiving an implantable cardioverter-defibrillators (ICDs) are at the greatest risk of cardiac death and benefit most from ICD therapy.
Abstract: Background: Patients resuscitated from ventricular tachyarrhythmias benefit from implantable cardioverter-defibrillators (ICDs) as opposed to medical treatment. Patients with increased QRS duration receiving an ICD in the presence of heart failure are at greatest risk of cardiac death and benefit most from ICD therapy. Objective: To determine whether an increased QRS duration predicts cardiac mortality in ICD recipients. Design: Consecutive patients with heart failure in New York Heart Association functional class III were grouped according to QRS duration ( v ⩾ 150 ms, n = 26, group 2) and followed up for (mean (SD)) 23 (20) months. Patients: 165 patients were studied (80% men, 20% women); 73% had coronary artery disease and 18% had dilated cardiomyopathy. Their mean age was 62 (10) years and mean ejection fraction (EF) was 33 (14)%. They presented either with ventricular tachycardia (VT) or ventricular fibrillation (VF). Main outcome measures: Overall and cardiac mortality; recurrence rates of VT, fast VT, or VF. Results: Mean left ventricular EF did not differ between group 1 (33 (13)%) and group 2 (31 (15)%). Forty patients died (34 cardiac deaths). There was no difference in survival between patients with EF > 35% and ⩽ 35%. Cardiac mortality was significantly higher in group 2 than in group 1 (31.3% at 12 months and 46.6% at 24 months, v 9.5% at 12 months and 18.2% at 24 months, respectively; p = 0.04). The recurrence rate of VT was similar in both groups. Conclusions: Within subgroups at highest risk of cardiac death, QRS duration—a simple non-invasive index—predicts outcome in ICD recipients in the presence of heart failure.
TL;DR: Acute studies performed with hemodynamic measurements and nuclear imaging phase analysis demonstrate that QRS delay, particularly LBBB, creates electrical and mechanical dyssynchrony in patients with depressed left ventricular function.
Abstract: Heart failure remains a major cardiovascular health problem, afflicting 22 million individuals worldwide and approximately 5 million persons in the United States alone. Management of patients with this problem represents the largest single expense to Medicare. A common feature predictive of adverse clinical outcomes in patients with congestive heart failure is prolongation of the QRS duration. Several different types of studies suggested QRS delay was an independent risk factor for adverse outcome, particularly in patients with left ventricular dysfunction.1,2 These data were derived from both longitudinal population studies and retrospective studies performed in heart failure patients with pacemakers and “acquired” left bundle branch block (LBBB).1,2 The significance of QRS delay in heart failure patients is that this common finding may be observed in up to 30% of patients with moderate to severe heart failure.
Acute studies performed with hemodynamic measurements and nuclear imaging phase analysis demonstrate that QRS delay, particularly LBBB, creates electrical and mechanical dyssynchrony in patients with depressed left ventricular function. Delayed and inhomogeneous left ventricular activation reduces stroke volume, left ventricular ejection fraction, and time for aortic ejection. Reductions in left ventricular dP/dT, increased left ventricular end-systolic and diastolic volumes, and abnormal patterns of wall stretch are also seen.3–5 Additionally, ventricular dyssynchrony promotes functional mitral regurgitation. Acutely pacing the right and left ventricle simultaneously or pacing the left ventricle alone results in marked improvements and restoration of a more homogeneous contraction pattern (Figure 1 and Figure 2⇓).
Figure 1. The upper panels represent phase images obtained during normal sinus rhythm with LBBB and during atrial sensed CRT. The contraction sequence is indicated by the color bar from early (green) to late (yellow). The histograms below each image illustrate the dispersion of the phase angle O, computed for the RV and LV blood pools. …
TL;DR: Cardiac resynchronization therapy attempts to restore contractile coordination in hearts burdened by wall motion dyssynchrony due to conduction delay by stimulating the region of the ventricle with the most delayed mechanical activation so it can contract.
TL;DR: The presence of cardiac diseases was characterized by LV global mechanical delay; and, intraventricular asynchronized contraction characterized mostly by further mechanical delay in the free‐wall region, even in those with normal QRS duration.
Abstract: LV electromechanical delay results in asynchronized contraction. However, it is not known if the presence of cardiac diseases without QRS prolongation may result in inter- or intraventricular asynchrony. This study investigated the occurrence of systolic mechanical delay in different regions of the LV in patients with underlying heart diseases and normal QRS duration. Tissue Doppler imaging (TDI) was performed in 141 patients (age 63.7 +/- 11.5 years) with underlying heart diseases (82% had ischemic heart disease) and 92 normal healthy volunteers (age 63.9 +/- 9.8 years) based on the four-basal and four-mid-segment model by apical views. Of these, 124 patients had normal QRS duration ( 50 ms (47 vs 24%, chi-square = 4.6, P < 0.05). In conclusion, the presence of cardiac diseases was characterized by LV global mechanical delay; and, intraventricular asynchronized contraction characterized mostly by further mechanical delay in the free-wall region. These changes occur even in those with normal QRS duration.
Patent•
29 Aug 2003TL;DR: In this paper, wavelet transforms are applied to the sampled amplitude values of a sequence of QRS complexes to develop wavelet transform coefficient (WTC) data sets, at least selected ones of the WTC data sets are processed and comparisons are made to determine a wavelet match score.
Abstract: Methods and apparatus are provided for discriminating high rate polymorphic QRS complexes from high rate monomorphic QRS complexes to increase the specificity of detection of polymorphic VT and VF employing wavelet transform signal processing of the QRS complexes are disclosed. Wavelet transforms are applied to the sampled amplitude values of a sequence of QRS complexes to develop wavelet transform coefficient (WTC) data sets. At least selected ones of the WTC data sets are processed and comparisons are made to determine a wavelet match score. A determination is made as a function of the wavelet match scores of the series of successive QRS complexes that characterizes the most recent QRS complex as more or less likely to signify polymorphic VT or VF.
TL;DR: Identification of abnormal conduction during pace-mapping can be used to focus mapping during induced VT to a discrete region of the infarct during stable sinus rhythm without mapping during VT.
TL;DR: The data showed that in wide and narrow QRS patients, Biv‐P significantly improved clinical parameters (NYHA class, 6‐minute walk test, quality‐of‐life, and hospitalization rate) and main echocardiographic indicators.
Abstract: Congestive heart failure (CHF) patients with LBBB and QRS duration > 150 ms are considered the best candidates to biventricular pacing (Biv-P). However, patients with a narrow (120-150 ms) QRS may also benefit from Biv-P since true ventricular dyssynchrony may be underestimated by considering only QRS enlargement. From October 1999 to April 2002, 158 CHF patients (121 men, mean age 65 years, mean LVEF 0.29, mean QRS width 174 ms) underwent successful Biv-P implantation and were then followed for a mean time of 11.2 months. According to basal QRS duration, patients were divided in two groups, with wide QRS (> or = 150 ms, 128 patients, 81%) and with narrow QRS (< 150 ms, 30 patients, 19%). In the wide QRS group, LVEF improved from 29% to 39% (P < 0.0001), 6-minute walk test from 311 to 463 m (P < 0.0001), while NYHA Class III-IV patients decreased from 86% to 8% (P < 0.0001). In the narrow QRS group LVEF improved from 30% to 38% (P < 0.0001), 6-minute walk test from 370 to 506 m (P < 0.0001), and NYHA Class III-IV patients decreased from 60% to 0% (P < 0.0001). The data showed that in wide and narrow QRS patients, Biv-P significantly improved clinical parameters (NYHA class, 6-minute walk test, quality-of-life, and hospitalization rate) and main echocardiographic indicators. Furthermore, narrow QRS patients had a better survival rate, rapidly regained left ventricular function, and only a few patients remained in a higher NYHA class during follow-up. These patients should not be excluded "a priori" from cardiac resynchronization therapy.
TL;DR: Extended QRS duration is a strong independent marker of long-term mortality in patients who undergo risk stratification for ventricular arrhythmias and whether modification of this factor using resynchronization therapies will impact mortality merits further study.
Abstract: This study tested the hypothesis that prolonged QRS duration independently predicts long-term mortality in patients who underwent risk stratification and treatment for ventricular arrhythmias. Patients who underwent risk stratification by electrophysiologic study were identified. Electrophysiologic study results were defined as positive if sustained monomorphic ventricular tachycardia was induced. Mortality was the primary end point. Of 915 patients studied, mean left ventricular (LV) ejection fraction (EF) was 35.3 ± 15.7%, 608 (66.4%) had coronary artery disease, 233 (25.5%) had positive electrophysiologic study findings, 298 (32.6%) received implantable cardioverter-defibrillators, and 174 (19%) died (mean follow-up 35.0 ± 15.0 months). Cox regression analysis identified older age, coronary artery disease, digoxin use, absence of β blockers, lower LVEF, and prolonged QRS duration to be independent predictors of mortality. QRS duration ≥130 ms, present in 33.6% of patients, was associated with a twofold increase in mortality (hazard ratio 2.1, 95% confidence interval 1.5 to 2.8; p
TL;DR: Relatively rapid heart rate, high QRS voltage, and first‐degree AV block are important clues suggesting TPP in patients who present with hypokalemia and paralysis.