Showing papers on "QRS complex published in 2001"
TL;DR: In this article, transvenous atriobiventricular pacemakers (with leads in one atrium and each ventricle) were used to reduce ventricular asynchrony.
Abstract: BACKGROUND: One third of patients with chronic heart failure have electrocardiographic evidence of a major intraventricular conduction delay, which may worsen left ventricular systolic dysfunction through asynchronous ventricular contraction. Uncontrolled studies suggest that multisite biventricular pacing improves hemodynamics and well-being by reducing ventricular asynchrony. We assessed the clinical efficacy and safety of this new therapy. METHODS: Sixty-seven patients with severe heart failure (New York Heart Association class III) due to chronic left ventricular systolic dysfunction, with normal sinus rhythm and a duration of the QRS interval of more than 150 msec, received transvenous atriobiventricular pacemakers (with leads in one atrium and each ventricle). This single-blind, randomized, controlled crossover study compared the responses of the patients during two periods: a three-month period of inactive pacing (ventricular inhibited pacing at a basic rate of 40 bpm) and a three-month period of active (atriobiventricular) pacing. The primary end point was the distance walked in six minutes; the secondary end points were the quality of life as measured by questionnaire, peak oxygen consumption, hospitalizations related to heart failure, the patients' treatment preference (active vs. inactive pacing), and the mortality rate. RESULTS: Nine patients were withdrawn from the study before randomization, and 10 failed to complete both study periods. Thus, 48 patients completed both phases of the study. The mean distance walked in six minutes was 22 percent greater with active pacing (399+/-100 m vs. 326+/-134 m, P<0.001), the quality-of-life score improved by 32 percent (P<0.001), peak oxygen uptake increased by 8 percent (P<0.03), hospitalizations were decreased by two thirds (P<0.05), and active pacing was preferred by 85 percent of the patients (P<0.001). CONCLUSIONS: Although it is technically complex, atriobiventricular pacing significantly improves exercise tolerance and quality of life in patients with chronic heart failure and intraventricular conduction delay.
2,540 citations
TL;DR: CRT with LV free wall stimulation produced significantly better LV systolic performance compared with anterior stimulation, and further studies are warranted to prove the clinical superiority of theLV free wall as a site for long-term CRT.
Abstract: Background— Cardiac resynchronization therapy (CRT) improves systolic function in heart failure patients with ventricular conduction delay by stimulating the left ventricle (LV) or both ventricles (biventricular, BV). Optimal LV site selection is of major clinical interest for CRT device implantation; however, the dependence of hemodynamics on LV stimulation site has not been established. Thus, the objective of this study was to compare the hemodynamic response to CRT for 2 LV coronary vein sites: the free wall and anterior wall. Methods and Results— A total of 30 patients (mean NYHA class, 2.7; mean QRS interval, 152 ms; mean PR interval, 194 ms) enrolled in the PATH-CHF-II trial were studied. CRT was administered with LV and BV stimulation in VDD mode at 4 AV delays. LV stimulation was at the lateral free wall or anterior wall, whereas right ventricular stimulation was fixed near the apex. LV+dP/dtmax and aortic pulse pressure changes from baseline during CRT were compared for LV sites. Free wall sites ...
634 citations
TL;DR: In this article, the tricuspid annular velocities were used as indexes of right ventricular function in patients with heart failure using pulsed Doppler tissue echocardiography.
Abstract: Aims Rapid, accurate, and widely available non-invasive evaluation of right ventricular function still presents a problem. The purpose of the study was to determine whether the parameters derived from Doppler tissue imaging of tricuspid annular motion could be used as indexes of right ventricular function in patients with heart failure.
Methods Standard and pulsed Doppler tissue echocardiography were obtained in 44 patients with heart failure (mean left ventricular ejection fraction 24±7%) and in 30 age- and sex-matched healthy volunteers. The tricuspid annular systolic and diastolic velocities were acquired in apical four-chamber views at the junction of the right ventricular free wall and the anterior leaflet of the tricuspid valve using Doppler tissue imaging. Within 2h of Doppler tissue imaging, the first-pass radionuclide ventriculogram, determining right ventricular ejection fraction and equilibrium gated radionuclide ventriculography single photon emission computed tomography, were performed in all patients.
Results In patients with heart failure, the peak systolic annular velocity was significantly lower and the time from the onset of the electrocardiographic QRS complex to the peak of systolic annular velocity was significantly greater than the corresponding values in healthy subjects (10·3±2·6cm.s−1vs 15·5±2·6cm.s−1, P <0·001, and 198±34ms vs 171±29ms, P <0·01, respectively). There was a good correlation between systolic annular velocity and right ventricular ejection fraction (r=0·648, P <0·001). A systolic annular velocity <11·5cm.s−1predicted right ventricular dysfunction (ejection fraction <45%) with a sensitivity of 90% and a specificity of 85%.
Conclusion We conclude that the evaluation of peak systolic tricuspid annular velocity using Doppler tissue imaging provides a simple, rapid, and non-invasive tool for assessing right ventricular systolic function in patients with heart failure.
627 citations
TL;DR: A new robust algorithm for QRS detection using the first differential of the ECG signal and its Hilbert transformed data to locate the R wave peaks in theECG waveform with a high degree of accuracy.
497 citations
TL;DR: The effects of pulmonary valve replacement (PVR) on certain electrocardiographic markers predictive of monomorphic ventricular arrhythmia and sudden death and sustained atrial flutter/fibrillation and monomorphic Ventricular tachycardia are examined.
Abstract: Background—Chronic pulmonary regurgitation after repair of tetralogy of Fallot (TOF) may lead to right ventricular dilatation, which may be accompanied by ventricular tachycardia and sudden death. We aimed to examine the effects of pulmonary valve replacement (PVR) on (1) certain electrocardiographic markers predictive of monomorphic ventricular arrhythmia and sudden death and (2) sustained atrial flutter/fibrillation and monomorphic ventricular tachycardia. Methods and Results—We studied 70 patients who underwent PVR for pulmonary regurgitation and/or right ventricular outflow tract obstruction late after repair of TOF. Maximum QRS duration and QT dispersion were measured from standard ECGs before PVR and at the latest follow-up. Arrhythmia was defined as sustained atrial flutter/fibrillation or sustained monomorphic ventricular tachycardia. Concomitant intraoperative electrophysiological mapping and/or cryoablation were performed in 9 patients (60%) with preexisting ventricular tachycardia and 6 patient...
417 citations
TL;DR: In the presence of impaired LV function with long-term RV apical pacing, alternative sites of ventricular pacing that simulate normal biventricular electrical activation should be explored to preserve function in pediatric patients in need of long- term pacing.
372 citations
TL;DR: Normal heart VT with left bundle branch block, inferior axis and early precordial transition can be ablated in the majority of patients from either the left or the noncoronary aortic sinus of Valsalva.
269 citations
TL;DR: Transverse left ventricular pacing through the coronary sinus is feasible and safe and the rate of implantation failure and of lead related problems has decreased greatly with increasing experience and with improvements in the equipment.
Abstract: BACKGROUND Biventricular pacing has been proposed as an adjuvant to optimal medical treatment in patients with drug refractory heart failure caused by chronic left ventricular systolic dysfunction and intraventricular conduction delay. OBJECTIVE To assess the technical feasibility and long term results (over six years) of transverse left ventricular pacing with the lead inserted into a tributary vein of the coronary sinus. SUBJECTS From August 1994 to February 2000, left ventricular lead implantation was attempted in 116 patients who were eligible for biventricular pacing (mean (SD) age 67 (9) years, New York Heart Association (NYHA) functional class III/IV, left ventricular ejection fraction 22 (6)%, QRS duration 185 (26) ms). RESULTS The overall implantation success rate was 88% (n = 102). A learning curve was indicated by a progressive increase in success from 61% early on to 98% in the last year. The mean pacing threshold was 1.1 (0.7) V/0.5 ms at the time of implantation and increased slightly up to 1.9 (0.9) V/0.5 ms at the end of the follow up period (15 (13) months). The rate of acute and delayed left ventricular lead dislodgement decreased from 30% in the early years to 11% after 1999. During follow up, 19 patients required reoperation for delayed lead dislodgement or increase in left ventricular pacing threshold (n = 15), phrenic nerve stimulation (n = 3), or infection (n = 3). CONCLUSIONS Transverse left ventricular pacing through the coronary sinus is feasible and safe. The rate of implantation failure and of lead related problems has decreased greatly with increasing experience and with improvements in the equipment.
236 citations
TL;DR: QRS duration is a good marker of an interventricular mechanical asynchrony and may be mainly proposed to symptomatic DCM patients with QRS duration > 150 ms.
Abstract: The aim of the study was to define criteria for left ventricular pacing in dilated cardiomyopathy (DCM) using an echocardiographic evaluation of interventricular electromechanical delay (IMD) and a correlation of IMD to QRS duration. Standard 12-lead ECG and echocardiography with pulsed Doppler tissue imaging (DTI) were recorded in 35 DCM patients (mean age 58 +/- 11 years) with QRS duration from narrow (80 ms) to broad (222 ms) patterns. The timefor left ventricular activation was evaluated from the onset of QRS to the onset of aortic flow (Q-Ao) by standard pulsed Doppler (SP) or to the onset of mitral annulus systolic wave (Q-Mit) (DTI). The time for right ventricular activation was determinedfrom the onset of QRS to the onset of pulmonary flow (Q-Pulm) (SP) or to the onset of tricuspid annulus systolic wave (Q-Tri) (DTI). (Q-Ao)-(Q-Pulm) and (Q-Mit)-(Q-Tri) determined IMD for each method, respectively. QRS width and IMD showed correlation coefficients of r = 0.86 ([Q-Ao]-[Q-Pulm]) and r = 0.82 ([Q-Mit]-[Q-Tri]) (P 150 ms.
188 citations
TL;DR: TDI is useful in assessing the severity of LV asynchrony in patients with LBBB with heart failure as well as in evaluating the pacing effects on long-axis function in these patients.
180 citations
TL;DR: QRS dispersion (≥40 ms) was the strongest independent predictor of sudden death in ARVC, and Syncope, QT dispersion >65 ms, and negative T wave beyond V1 refined arrhythmic risk stratification in these patients.
Abstract: Background—We retrospectively investigated the value of clinical and ECG findings as well as QT-QRS dispersion in predicting the risk of sudden death in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Methods and Results—Duration and interlead variability of the QT interval and QRS complex were measured manually from standard ECGs in 20 sudden death victims with ARVC diagnosed at autopsy (group I), in 20 living ARVC patients with sustained ventricular tachycardia (group II), in 20 living ARVC patients with ≤3 consecutive premature ventricular beats (group III), and in 20 control subjects (group IV). QT and QRS dispersions were greater in group I (77.5±10.6 ms for QT and 45.7±8.1 ms for QRS) compared with group II (64.5±13.9 ms for QT [P=0.001] and 33.5±8.7 ms for QRS [P=0.0004]) and in group II compared with group III (48±8.9 ms for QT [P<0.0001] and 28±5.2 ms for QRS [P<0.0001]) and group IV (33.5±4.8 ms for QT [P<0.0001] and 18.5±3.6 ms for QRS [P<0.0001]). Negative T wave beyond V...
TL;DR: In patients with a wide QRS, drug-resistant heart failure, and a coronary sinus that is unsuitable for transvenous biventricular pacing (BVP), endocardial BVP provides more homogenous intraventricular resynchronization than epicardian BVP and is associated with better LV filling and systolic performance.
Abstract: In patients with a wide QRS, drug-resistant heart failure, and a coronary sinus that is unsuitable for transvenous biventricular pacing (BVP), a transseptal approach from the right to left atrium can allow endocardial left ventricular (LV) pacing (with permanent anticoagulant therapy) instead of epicardial pacing via the coronary sinus branches. We sought to compare the effects of endocardial pacing with those of epicardial LV pacing on regional LV electromechanical delay (EMD) and contractility. Twenty-three patients (68 ± 8 years) with severe heart failure and QRS ≥130 ms received a pacemaker for BVP. Fifteen patients underwent epicardial LV pacing, and 8 underwent endocardial LV pacing because of an unsuitable coronary sinus. All LV leads were placed at the anterolateral LV wall. Six months after implant, echocardiography and Doppler tissue imaging were performed. LV wall velocities and regional EMDs (time interval between the onset of the QRS and local ventricular systolic motion) were calculated for the 4 LV walls and compared for each patient between right ventricular (RV) and BVP. The amplitude of regional LV contractility was also assessed. Epicardial BVP reduced the septal wall EMD by 11% versus RV pacing (p = 0.05) and the lateral wall EMD by 41% versus RV pacing (p <0.01). With endocardial BVP, the septal and lateral EMDs were 21.3% and 54%, respectively (p <0.01, compared with epicardial BVP). The mitral time-velocity integral increased by 40% with endocardial BVP versus 2% with epicardial BVP (p <0.01). The amplitude of the lateral LV wall systolic motion increased by 14% with epicardial BVP versus 31% with endocardial BVP (p = 0.01). This resulted in a LV shorterning fraction increase of 25% in patients with endocardial BVP (p = 0.05). However, all patients were clinically improved at the end of follow-up. Thus, in heart failure patients with BVP, endocardial BVP provides more homogenous intraventricular resynchronization than epicardial BVP and is associated with better LV filling and systolic performance.
TL;DR: Assessment of the predictive significance of various noninvasive risk indicators of mortality, including TWA, in consecutive post‐AMI patients with optimized medical therapy found them to be well established.
Abstract: Noninvasive Risk Assessment Including TWA After AMI.Introduction: Occurrence of sustained microvolt-level T wave alternans (TWA) at a specified heart rate has been suggested to predict life-threatening arrhythmic events, but its prognostic value has not been well established in patients who survived an acute myocardial infarction (AMI). The purpose of this prospective study was to assess the predictive significance of various noninvasive risk indicators of mortality, including TWA, in consecutive post-AMI patients with optimized medical therapy.
Methods and Results: In addition to a symptom-limited predischarge exercise test with measurement of TWA, mortality risk was assessed using heart rate variability, 24-hour ECG recordings, baroreflex sensitivity, signal-averaged ECG, QTc interval, QT dispersion, and echocardiographic wall-motion index in 379 consecutive patients. Twenty-six patients (6.9%) died during a mean follow-up of 14 ± 8 months. Sustained TWA was found in 56 patients (14.7%), none of whom died. Several risk variables, e.g., incomplete TWA test (inability to perform the exercise test or reach the required target heart rate of 105 beats/min), increased QRS duration on signal-averaged ECG, increased QT dispersion, long QTc interval, nondiagnostic baroreflex sensitivity result, and low wall-motion index, predicted all-cause mortality in univariate analyses. In multivariate analysis, the incomplete TWA test was the most significant predictor of cardiac death (relative risk 11.1, 95% confidence interval 2.4 to 50.8; P < 0.01).
Conclusion: Sustained TWA during the predischarge exercise test after AMI does not indicate increased risk for mortality. An incomplete TWA test and several common risk variables provided prognostic information in this post-AMI population.
Book•
01 Jan 2001
TL;DR: Normal Electrocardiogram: Origin and Description Atrial Abnormalities Ventricular Enlargement Left Bundle Branch Block Right bundle Branch Block Other Intraventricular Conduction Disturbances ElectrocardIographic Patterns of Acute Ischemia Myocardial Infarction and Electrocard iographic patterns Simulating MyocardIAL Infarctions Non-Q-Wave Myocardials, Unstable Angina Pectoris, and Myocardia Stress Test
Abstract: Normal Electrocardiogram: Origin and Description Atrial Abnormalities Ventricular Enlargement Left Bundle Branch Block Right Bundle Branch Block Other Intraventricular Conduction Disturbances Electrocardiographic Patterns of Acute Ischemia Myocardial Infarction and Electrocardiographic Patterns Simulating Myocardial Infarction Non-Q-Wave Myocardial Infarction, Unstable Angina Pectoris, and Myocardial Ischemia Stress Test Pericarditis and Cardiac Surgery Patterns in Diseases of the Heart and Lungs Sinus Rhythms Atrial Rhythms Atrial Fibrillation and Atrial Flutter Atrioventricular Junctional Rhythms Arrhythmias Ventricular Torsade De Pointes, Ventricular Fibrillation, and Differential Diagnosis of Wide QRS Tachycardias Atrioventricular Block Concealed Conductioin Gap Phenomenon Venticular Pre-Excitation (Wolf-Parkinson-White and its Variants) Effect of Drugs on the Electrocardiogram Electrolytes, Temperature, Diseases of Central Nervous System, and Miscellaneous Effects T-Wave Abnormalities QT-Interval, U-Wave Abnormalities, and Cardiac Alternans Recognition of Misplacement of Leads and Electrocardiographic Artifacts Artificial Electronic Pacemakers Ambulatory Electrocardiography
TL;DR: Attenuation of ECG voltage in patients with AN correlates with WT gain, and it can be attributed to a shunting of the cardiac potentials due to the low resistance of the AN fluid.
TL;DR: Abnormal depolarization-repolarization in patients with repaired tetralogy of Fallot (TOF) is a risk factor for malignant ventricular tachycardia and sudden death and it is unclear whether ECG abnormalities are associated with abnormal regional right ventricular (RV) function.
Abstract: Background—Abnormal depolarization-repolarization in patients with repaired tetralogy of Fallot (TOF) is a risk factor for malignant ventricular tachycardia and sudden death. It is unclear whether ECG abnormalities are associated with abnormal regional right ventricular (RV) function. Methods and Results—Seventy-four patients (37 patients 18 years old) who had had TOF repair at 4.0 years old (0.1 to 47 years old) were examined when they were 18.7 years old (1.7 to 61.1 years old), as were 112 control subjects with normal hearts. Regional function was evaluated with tissue Doppler imaging of the RV and left ventricular (LV) free wall and the septum. Myocardial velocities were sampled continuously from base to apex. Synchronous ECG was analyzed for QRS, QT, and JT duration and QRS, QT, and JT dispersion. All 74 TOF patients had normal LV myocardial velocities. Forty-eight patients (24 patients 18 years old) had reversed myocardial velocities in diastole in the RV free wall, which wer...
TL;DR: Resynchronization pacing led to a significant increase in arterial blood pressure and was a useful adjunct to the treatment of acute postoperative heart failure in patients with AV and/or IV conduction delay.
Abstract: The acute hemodynamic effect of atrioventricular (AV) and inter/intraventricular (IV) resynchronization accomplished by temporary pacing using multiple epicardial pacing wires was evaluated in 20 children (aged 3.4 months to 14.0 years) after surgery for congenital heart defects fulfilling the following criteria: (1) presence of AV and/or IV conduction delay, and (2) need for inotropic support. AV resynchronization (n = 13) was achieved by AV delay optimization during atrial synchronous right ventricular outflow tract pacing. IV resynchronization (n = 14) was accomplished by atrial synchronous pacing from the right ventricular lateral wall in 7 patients with right bundle branch block and normal AV conduction and by atrial synchronous multisite ventricular pacing in another 7 patients with previously performed AV resynchronization. Compared with baseline values, AV resynchronization resulted in an increase in arterial systolic, mean, and pulse pressures by 7.2 ± 8.3% (p <0.01), 8.6 ± 8.1% (p <0.005), and 6.9 ± 13.5% (p = NS), respectively. IV resynchronization used either alone or added to previously performed AV resynchronization led to a pressure increase of 7.0 ± 4.7%, 5.9 ± 4.7%, and 9.4 ± 7.8%, respectively (p <0.001 for all). The combined effect of AV and IV resynchronization resulted in a systolic, mean, and pulse pressure increase of 10.2 ± 5.0% (range 4.0 to 19.1), 8.6 ± 5.4% (range 0.8 to 14.8), and 15.2 ± 8.5% (range 6.1 to 33.3), respectively (p <0.001 for all). The increase in systolic arterial pressure after IV resynchronization was positively correlated with the initial QRS duration (r = 0.62, p <0.05) and extent of QRS shortening (r = 0.66, p <0.05). In conclusion, resynchronization pacing led to a significant increase in arterial blood pressure and was a useful adjunct to the treatment of acute postoperative heart failure in patients with AV and/or IV conduction delay.
TL;DR: The ECG should not only tell you how to distinguish VT from other tachycardias with a broad QRS complex, but also to suspect its aetiology and its site of origin in the ventricle.
Abstract: When confronted with a tachycardia having a broad QRS complex, it is important to be able to differentiate between a supraventricular and a ventricular tachycardia. Medication given for the treatment of a supraventricular tachycardia (SVT) may be harmful to a patient with a ventricular tachycardia (VT).1 2 A reasonable haemodynamic condition during a tachycardia may erroneously lead to the wrong diagnosis of SVT.3 Familiarity with the ECG signs allowing the diagnosis of a VT is therefore essential. But as will be discussed here, the ECG should not only tell you how to distinguish VT from other tachycardias with a broad QRS complex, but also to suspect its aetiology and its site of origin in the ventricle. Both aspects are important in decision making about the prognostic significance of VT and correct treatment.
As shown in fig 1, broad QRS tachycardia can be divided in three groups.
Patent•
05 Nov 2001TL;DR: In this article, a T-wave is delivered on the T wave of a patient's cardiac waveform by first detecting the occurrence of a QRS complex in the waveform and using that detection to set up for detection of the following T wave.
Abstract: A shock is delivered on the T-wave of a patient's cardiac waveform by first detecting the occurrence of a QRS complex in the waveform and using that detection to set up for detection of the following T-wave. Narrowband filtering is used to first select the QRS complex and thereafter the T-wave, while peak detection is employed to define the actual occurrence of the respective waveforms. The capability is also provided to deliver the shock at a manually selected interval after QRS detection or after a coupling interval in a pacing application.
Patent•
29 Jun 2001TL;DR: In this article, a system and method for monitoring the QRS duration, processing such signals to provide data from which the onset or progression of heart failure is determined, and adjusting synchronous pacing delay parameters including SAV delay and/or PAV delay to enhance cardiac output as a function of QRS delay is provided.
Abstract: Bi-Ventricular or AV synchronous cardiac pacing systems that pace and sense in at least one atrial heart chamber and deliver ventricular pacing pulses to right ventricular (RV) and left ventricular (LV) sites separated by a V—V delay for treatment of heart failure are disclosed that optimize one or more of the AV delay and V—V delay to enhance left ventricular filling and cardiac output as a function of QRS duration. A system and method for monitoring the QRS duration, processing such signals to provide data from which the onset or progression of heart failure is determined, and adjusting synchronous pacing delay parameters including SAV delay and/or PAV delay and/or V—V delay to enhance cardiac output as a function of QRS duration is provided. The SAV, PAV, and/or the V—V delays can be varied from the prevailing delays as a function of measured QRS duration so as to minimize the width of the QRS complex.
TL;DR: Biventricular pacing improves LV systolic performance and reduces LV volumes during short-term treatment and provides important pathophysiological information on the degree of LV resynchronization and may contribute to improved patient selection.
Abstract: Objectives: We used tissue velocity imaging (TVI) and three-dimensional echocardiography to evaluate the effect of acute biventricular pacing on left ventricular (LV) performance and volumes in patients with severe heart failure and bundle branch block. Background: Biventricular pacing causes acute hemodynamic improvement in patients with severe heart failure, and QRS duration has been used as a predictor of improved resynchronization. Tissue velocity has the potential of demonstrating the degree of LV resynchronization and three-dimensional echocardiography enables accurate quantitation of LV volumes and function. Methods: TVI and three-dimensional echocardiography were performed during sinus rhythm and biventricular pacing in 25 consecutive patients with severe heart failure. Results: Biventricular pacing significantly improved the extent of contracting myocardium in synchrony by 15.4% and the duration of contraction synchrony by 17% (p Conclusion: Biventricular pacing improves LV systolic performance and reduces LV volumes during short-term treatment. TVI provides important pathophysiological information on the degree of LV resynchronization and may contribute to improved patient selection.
TL;DR: A patient with massive cocaine ingestion who developed psychomotor agitation and generalized seizures followed by asystolic cardiac arrest is reported, and the electrocardiogram showed accelerated junctional rhythm at 85 beats/min resembling the Brugada syndrome.
TL;DR: The electrocardiographic findings associated with pulmonary embolism have been well described in the medical literature for over 50 years and may reflect hemodynamic changes, such as right heart strain, as well as myocardial ischemia associated with the disease.
Abstract: The electrocardiographic findings associated with pulmonary embolism have been well described in the medical literature for over 50 years. These abnormalities include changes in rhythm, QRS axis, and morphology, particularly in the QRS and T waves. Such findings may reflect hemodynamic changes, such as right heart strain, as well as myocardial ischemia associated with the disease. Although certain findings may correlate with the severity of pulmonary embolism, the overall utility of the electrocardiogram is limited due to the variable presence, frequency, and transient nature of most of the abnormalities associated with the disease.
TL;DR: Significant differences exist between athletes with early repolarization and patients with the Brugada syndrome as regards the amplitude of ST elevation and QRS duration.
Abstract: Aim To re-examine the prevalence and presentation of early repolarization in athletes and to compare it with electrocardiographic abnormalities observed in patients with the Brugada syndrome.
Methods Electrocardiograms of 155 male athletes and 50 sedentary controls were studied. Early repolarization was considered present if at least two adjacent precordial leads showed elevation of the ST segment ≥1mm. Amplitude and morphology of ST elevation, the leads where it was present and the lead in which it showed its maximum value were analysed together with QRS duration, the presence of right ventricular activation delay, QT and QTc duration. Data were compared with those obtained by electrocardiograms of 23 patients with the Brugada syndrome.
Results Early repolarization was found in 139 athletes (89%) and 18 controls (36%, P ≤0·025), being limited to right precordial leads in 42 (30%) athletes and 13 (72%) controls ( P ≤0·001). Only 12 (8·6%) athletes and one control (5·5%) with early repolarization had an ST elevation ‘convex toward the top’ in right precordial leads, similar to that seen in the Brugada syndrome. In athletes the maximum ST elevation was greater (2·3±0·6mm) than in the controls (1·2±0·8mm; P ≤0·004) but significantly lower than in patients with the Brugada syndrome (4·4±0·7mm; P ≤0·0001). Patients with the Brugada syndrome also had a greater QRS duration (0·11±0·02s) than athletes (0·090±0·011s; P ≤0·0001) with early repolarization.
Conclusions Early repolarization is almost always the rule in athletes but it is also frequent in sedentary males. Tracings somewhat simulating the Brugada syndrome were observed in only 8% of athletes without a history of syncope or familial sudden death. Significant differences exist between athletes with early repolarization and patients with the Brugada syndrome as regards the amplitude of ST elevation and QRS duration.
TL;DR: Presence of QRS prolongation independently predicted higher mortality in patients with left ventricular systolic dysfunction, and this finding may have important prognostic and therapeutic implications in this patient population.
Abstract: Survival analysis was performed on a cohort of 2,265 patients with left ventricular ejection fraction of
TL;DR: It is hypothesized conversely that altering the pattern of ventricular activation causes gap junctional remodeling, and has been causally implicated in reentrant arrhythmogenesis.
Abstract: Gap Junctional Remodeling in Paced Ventricle.Introduction: Prolonged arrhythmic or paced ventricular activation causes persistent changes in myocardial conduction and repolarization that may result from altered electrotonic current flow, for which gap junctional coupling is the principal determinant. Remodeling of gap junctions and their constituent connexins modifies conduction and has been causally implicated in reentrant arrhythmogenesis. We hypothesized conversely that altering the pattern of ventricular activation causes gap junctional remodeling.
Methods and Results: Seven dogs were paced from the left ventricular (LV) epicardium (VVO, ~120 beats/min) for 21 days before excision of transmural LV samples that were divided into endomyocardial, mid-myocardial, and epimyocardial layers. Another five paced dogs had recording electrodes attached to multiple LV sites. All 12 dogs developed characteristic pacing-induced persistent T wave changes of cardiac memory. After 21 days of pacing, the ventricularly paced QRS duration prolonged by a mean of 4 msec over baseline (P < 0.05), a change that was associated with significant slowing of intraventricular conduction to local sites. These changes in QRS duration and repolarization were associated with a reduction in epimyocardial connexin43 expression on quantitative Western blotting of LV myocardium from close to, but not distant from, the pacing site (61.7 ± 18.4 vs 100.9 ± 34.0; P < 0.02) and a marked disruption in immunolabeled connexin43 distribution in epimyocardium only.
Conclusion: Spatially distinct transmural and regional gap junctional remodeling is a consequence of abnormal ventricular activation and is associated with consistent changes in activation that may alter patterns of repolarization and facilitate reentrant arrhythmogenesis.
TL;DR: This review focuses on the ECG and the various abnormalities seen in the patient with PE, including arrhythmias, nonspecific ST segment/T wave changes, T wave inversions in the right precordial leads, rightward QRS complex axis shift and other axis changes.
Abstract: The electrocardiogram (ECG) may be entirely normal in the patient with pulmonary embolism (P/E); alternatively, any number of rhythm and/or morphologic abnormalities may be observed in such a patient. The abnormal ECG may deviate from the norm with alterations in rhythm, in conduction, in axis of the QRS complex, and in the morphology of the P wave, QRS complex, and ST segment/T wave. The electrocardiographic findings associated with PE are numerous, including arrhythmias (sinus tachycardia, atrial flutter, atrial fibrillation, atrial tachycardia, and atrial premature contractions), nonspecific ST segment/T wave changes, T wave inversions in the right precordial leads, rightward QRS complex axis shift and other axis changes, S1Q3 or S1Q3T3 pattern, right bundle branch block, and acute cor pulomnale. This review focuses on the ECG and the various abnormalities seen in the patient with PE.
TL;DR: The findings indicate that the presence and severity of cardiac tamponade, in addition to inflammatory mechanisms, may contribute to the development of low QRS voltage in patients with large pericardial effusions.
TL;DR: The spatial QRS-T angle was significantly increased in those treated hypertensive patients who showed repeatedly high BP values, suggesting that the angle between the directions of ventricular depolarisation and repolarisation is a sensitive marker of theRepolarisation alterations in systemic hypertension.
Abstract: Ventricular repolarisation abnormalities are important in arrhythmia provocation. The dispersion of repolarisation duration is not the only aspect of repolarisation heterogeneity. Spatial vectorcardiographic descriptors constitute a novel approach to quantify ventricular repolarisation. To test the ability of vectorcardiographic descriptors to discriminate between hypertensives with high or low blood pressure (BP), 110 treated hypertensives (mean age 63.6 ± 12.1 years) were classified in the high (systolic BP ⩾160 mm Hg or diastolic BP ⩾95 mm Hg) (n = 67), or the low (systolic BP < 160 mm hg and diastolic bp <95 mm hg) (n = 43) BP group. The maximum QT, JT, and T peak–T end intervals and the QT, JT, and T peak–T end dispersion were calculated from a digitally recorded 12-lead electrocardiogram (ECG). X, Y, and Z leads were reconstructed from the 12-lead ECG. The amplitude of the maximum spatial T vector (spatial T amplitude), the angle between the maximum spatial QRS and T vectors (spatial QRS-T angle) and the frontal plane QRS-T angle were calculated. The spatial QRS-T angle was higher in patients with high compared to those with low BP (P = 0.025). All conventional ECG markers of the dispersion of ventricular repolarisation duration failed to demonstrate significant differences between hypertensives with high or low BP. In conclusion, the spatial QRS-T angle was significantly increased in those treated hypertensive patients who showed repeatedly high BP values. Hence, we may suggest that the angle between the directions of ventricular depolarisation and repolarisation is a sensitive marker of the repolarisation alterations in systemic hypertension.
TL;DR: In five of 15 consecutive patients with heart failure and left bundle branch block, biventricular pacing induced a more than 15% increase in FSV, which predicted aMore than 25% increaseIn walking distance and was accompanied by an immediate reduction in left ventricular chamber size and mitral regurgitation.
Abstract: OBJECTIVES—To quantify the short term haemodynamic effects of biventricular pacing in patients with heart failure and left bundle branch block by using three dimensional echocardiography.
DESIGN—Three dimensional echocardiography was performed in 15 consecutive heart failure patients (New York Heart Association functional class III or IV) with an implanted biventricular pacing system. Six minute walk tests were performed to investigate the effect of biventricular pacing on exercise capacity. Data were acquired at sinus rhythm and after short term (2-7 days) biventricular pacing.
RESULTS—Compared with baseline values, biventricular pacing significantly reduced left ventricular end diastolic volume (EDV) by mean (SD) 4.0 (5.1)% (p < 0.01) and end systolic volume (ESV) by 5.6 (6.4)% (p < 0.02). Mitral regurgitant fraction was significantly reduced by 11 (12.1)% (p < 0.003) and forward stroke volume (FSV) increased by 13.9 (18.6)% (p < 0.02). Exercise capacity was significantly improved with biventricular pacing by 48.4 (43.3)% (p < 0.00001). Regression analyses showed that the percentage increase in FSV independently predicted percentage improvement in walking distance (r2 = 0.73, p < 0.0002). Both basal QRS duration and QRS narrowing predicted pacing efficacy, showing a significant correlation with %ΔEDV, %ΔESV, and %ΔFSV.
CONCLUSIONS—In five of 15 consecutive patients with heart failure and left bundle branch block, biventricular pacing induced a more than 15% increase in FSV, which predicted a more than 25% increase in walking distance and was accompanied by an immediate reduction in left ventricular chamber size and mitral regurgitation.
Keywords: heart failure; left ventricular volume; pacing; three dimensional echocardiography