bluuebunny/crossref_metadata_2025 huggingface dataset:
Reproducibility of QT Interval Measurements Obtained from 24‐Hour Digitized Ambulatory Three‐Lead Electrocardiograms in Patients with Acute Myocardial Infarction and Healthy Volunteers
Authors: Copie Xavier , Alonso Christine , Lavergne Thomas , Iliou Marie‐Christine , Guize Louis , Le Heuzey Jean‐Yves
Published: October 2006

Background

Changes in QT interval durations on 24‐hour ambulatory ECGs reflect circadian variations in ventricular repolarization. However, the reproducibility of such measurements is unknown.

Methods

Two 24‐hour Holter recordings were obtained in 9 healthy volunteers, and in 15 post‐myocardial infarction (Ml) patients. First, automated measurements of QT apex and QT end were compared with manual measurements. Second, automated measurements of QT intervals were compared for each subject between the first and second Holter recordings. The coefficient of reproducibility was calculated as twice the standard deviation of differences between paired measurements.

Results

The coefficient of reproducibility for the comparison of manual and automated measurements of QT apex was 9 ms in healthy volunteers and 12 ms in post‐MI patients. This coefficient was 12 ms in both healthy volunteers and post‐MI patients for the comparison of manual and automated measurements of QT end. The coefficient of reproducibility for the comparison of automated measures of QT apex in the two Holter recordings was 16 ms in healthy volunteers and 18 ms in post‐MI patients. These coefficients were 19 ms and 23 ms, respectively, for the comparison of automated measures of QT end.

Conclusions

Automated and manual measurements of QT intervals obtained from 24‐hour ambulatory ECGs provide similar results. Short‐term reproducibility of automated measurements of QT intervals is acceptable.
Tilt‐Table Testing in Syncopal Patients with Sick Sinus Syndrome: A Guide to Pathophysiology and Management?
Authors: Gatzoulis Kostas A. , Mamarelis Ioannis I. , Theopistou Artemis M. , Sideris Skevos K. , Avgeropoulou Katerina , Gialafos John H. , Toutouzas Pavlos K.
Published: October 2006

Background

A possible role of a neurally mediated component in the syncope mechanism of patients with sick sinus syndrome has not been adequately evaluated.

Methods

We examined and compared three groups: group 1, 25 syncopal patients (age 55 ± 15, M/F 18/7, syncope attacks per patient 6 ± 7) with sick sinus syndrome (persistent unexplained bradycardia with a long sinus pause and/or a long sinus node recovery time, a long sinoatrial conduction time, a low intrinsic heart rate, and/or an incompetent chronotropic response to atropine); group 2: 45 patients (age 43 ± 18, M/F 28/17, syncope attacks per patient 6 ± 7) with syncope of unknown etiology; group 3:20 healthy controls (age 34 ± 9, M/F 16/4). The tilt‐table test protocol used consisted of an initial 20‐minute period at 80° tilt followed by three 10‐minute periods in the same position under graded isoproterenol intravenous infusion at 1–3 μ;g/min. The test was considered positive if presyncope or syncope due to hypotension and/or bradycardia was induced.

Results

A similar proportion of group 1 and group 2 patients developed a positive test (12 or 48% and 25 or 56%, respectively, P:NS) with a similar positive tilt‐table test duration in both groups (41 ± 22 vs 43 ± 17 minutes, P:NS). In contrast, only four of the group 3 healthy controls (20%) developed a positive test with a much longer test duration (P < 0.005).

Conclusions

Syncopal patients with sick sinus syndrome commonly exhibit a neurally mediated syncope reaction during a tilt‐table test. This might explain the occasional failure to prevent recurrent syncope in sick sinus syndrome patients treated with cardiac pacing. Concurrent β‐blocker therapy may be indicated for such patients.
QT Dispersion: Comparison of Orthogonal, Quasi‐orthogonal, and 12‐Lead Configurations
Authors: Beuve Claude Sainte , Badilini Fabio , Blanche Pierre Maison , Kedra Antoni , Coumel Philippe
Published: October 2006

Background

Full standardization of QT dispersion has not yet been established; the influence of lead combination is still disputed. This study evaluates the respective value of automated QTc dispersion in orthogonal (XYZ), quasi‐orthogonal I‐aVF‐V2 (IF2), and 12‐lead ECG configurations.

Methods

15‐lead digitized ECG recordings were collected in 92 normal subjects and in 71 patients following myocardial infarction. Each lead was processed by an automatic algorithm. QT dispersion was assessed by the range of individual QT intervals, both corrected by Bazett's formula. QTc durations from all configurations were comparable (post‐MI: 412 ± 27 vs 407 ± 29 msec for 12‐lead and XYZ). Whatever the set of leads, QTc interval was longer in post‐MI (in 12‐lead, 412 ± 27 vs 397 ± 19 ms in normals, P < 0.001). QTc dispersion was larger on 12‐lead (post‐MI: 51 ± 19, 21 ± 13 and 28 ± 20 ms with 12‐lead, XYZ and IF2); however, it was significantly larger in post‐MI with all sets of leads (in XYZ, 21 ± 13 vs 9 ± 7 ms in normal subjects, P < 0.0001).

Conclusion

In conclusion, magnitude of QT dispersion depends on the set of leads considered; orthogonal configurations may still contain valuable prognostic information.
Baroreflex Sensitivity
Authors: La Maria Teresa Rovere
Published: October 2006

Background

Arterial baroreceptors play a central role in governing autonomic outflow to the heart and are involved in the electrophysiological mechanisms by which sympathetic activation may initiate a ventricular tachyarrhythmia and vagal activation may have antifibrillatory effects. Stimulation of arterial baroreceptors results in sympathoinhibition and efferent vagal activation. Cardiovascular disease may alter baroreceptor function leading to inappropriate or excessive autonomic activity in response to blood pressure changes.

Methods

Evidence obtained in an experimental preparation in chronically infarcted dogs opened the way to the understanding of the importance of the analysis of baroreceptor control of heart rate in risk stratification. Among several methodologies, the measurement of the reflex R‐R interval lengthening following a blood pressure rise induced by bolus injections of phenylephrine has been shown to provide clinically relevant information as a measure of the capability to augment vagal activity.

Results

Following pilot studies conducted by different groups of investigators, the Autonomic Tone and Reflexes After Myocardial Infarction (ATRAMI) trial in a series of 1284 myocardial infarction patients has demonstrated that the prognostic value of baroreflex sensitivity is largely independent from the established clinical predictors such as left ventricular ejection fraction and ventricular arrhythmias.

Conclusions

In these patients, the value of the information obtained by the combination between left ventricular function and baroreflex sensitivity suggests that this analysis should be included in the risk stratification strategy for identification of patients who may need an implantable automatic defibrillator for primary prevention of sudden cardiac death. The analysis of baroreceptor reflexes is of prognostic value also in patients with chronic heart failure.
Relationships of Chronic Hyperinsulinemia, Heart Rate Variability, and Circadian Variation of Blood Pressure in Obese Hypertensive Subjects
Authors: Galinier Michel , Fourcade Joëlle , Boveda Serge , Ley Nicolas , Solera Sophie , Solera Marie Laure , Pîrvu Octavian , Massabuau Pierre , Cabrol Philippe , Fauvel Jean Marie , Valdiguie Pierre , Bounhoure Jean Paul
Published: October 2006

Background:During insulin resistance, sympathetic nerve activity is increased. However insulin resistance is a common feature of obesity and essential hypertension, it is unclear if chronic hyperinsulinemia per se contributes to sympathetic overactivation. The purpose of our study was to explore the relationship between hyperinsulinemia and heart rate variability (HRV), a noninvasive tool to assess autonomic function, in obese and hypertensive subjects.

Methods:24‐hour Holter ECG for HRV time and frequency domain analysis was performed in 77 patients: mean age 53 ± 10 years; 52 men and 25 women; free of diabetes; without beta‐blockers. The patient were divided into four groups according to three parameters, body mass index (BMI > 27 kg/m2 in the men and > 25 kg/m2 in the women defined obesity), arterial pressure, and insulinemia (fasting insulinemia > 25 mUI/L defined hyperinsulinemia). Twenty‐seven patients were obese, hypertensive, with hyperinsulinemia; 28 patients obese, hypertensive, without hyperinsulinemia; 12 patients nonobese, hypertensive, without hyperinsulinemia; 10 patients obese, normotensive, without hyperinsulinemia.

Results:In comparison with the three other groups, patients with hyperinsulinemia showed a significant decrease (P < 0.05) of SDNN and the power of total spectrum (0.01–1 Hz) band, which are indexes of global HRV, and a significant decrease (P < 0.005) of SD and the normalized power of the low frequency (0.04–0.15 Hz) band, both indexes reflecting sympathetic modulation of HRV. In contrast, no significant difference was observed among the four groups for indexes of HRV reflecting parasympathetic tone. These relations were independent of mean R‐R. Fasting insulinemia was significantly (P < 0.0001) related with HRV in time domain (SDNN: r =−0.43; SD: r =‐0.49) and spectral domain (total spectrum: r =−0.49; low frequency: r =−0.52).

Conclusion:Chronic hyperinsulinemia appears to be an important determinant of HRV, particularly for the indexes reflecting sympathetic influence, independent of obesity and hypertension. A.N.E. 1999;4(3):316–324
Noninvasive Electrocardiographic Imaging
Authors: Rudy Yoram , Burnes John E.
Published: October 2006

Background:Cardiac arrhythmias continue to be a leading cause of death and disability. Despite this alarming fact, a noninvasive imaging modality for cardiac electrophysiology (EP) has not been developed. Standard electrocardiographic techniques attempt to infer electrophysiological processes in the heart from a limited number of recordings on the body surface. This traditional approach is limited in its ability to provide information on regional electrocardiac activity and to localize electrophysiological events in the heart (e.g., arrhythmogenic foci; regions of elevated dispersion of myocardial repolarization). This article reviews the development of a novel imaging modality (electrocardiographic imaging [ECGI]) for the reconstruction of cardiac electrical activity from potentials measured away from the heart (i.e., on the torso surface). The results presented demonstrate that ECGI can noninvasively reconstruct epicardial potentials, electrograms, and isochrones with good accuracy and resolution.

Results:The locations of ectopic pacing sites are reconstructed within 10 mm of their actual positions. Dual epicardial pacing sites separated by 52 mm, 35 mm, and 17 mm can be resolved. The depth of intramural ectopic activity can be estimated and the direction of intramural activation spread can be determined from the reconstructed epicardial potential pattern and its evolution in time. Results from infarcted hearts demonstrate that ECGI can detect and reconstruct the abnormal electrophysiological substrate associated with the infarct. The figure‐of‐eight pattern of reentrant activation in the epicardial border zone during ventricular tachycardia is also reconstructed by ECGI noninvasively.

Conclusions:These results demonstrate the potential of ECGI as a clinical noninvasive imaging modality for identifying patients at risk of cardiac arrhythmias and for guiding and evaluating antiarrhythmic interventions in such patients. A.N.E. 1999;4(3):340–359
Signal‐Averaged P Wave: Technique and Clinical Applications
Authors: Sadanandan Saihari , Steinberg Jonathan S.
Published: October 2006

BackgroundAtrial fibrillation is the most common arrhythmia encountered in clinical practice. Identification of factors predisposing to atrial fibrillation may have implications for its prevention and may facilitate the detection of patients most susceptible to atrial fibrillation and its sequelae. Prolongation of P wave duration representing intra‐atrial conduction delay is inadequately visualized in a standard electrocardiogram. Accurate detection, alignment, amplification and filtering of P waves during the signal averaging process permits a better analysis of the P wave and thus atrial conduction. Signal averaged P wave electrocardiography is a noninvasive technique that has permitted the evaluation of patients at risk of developing atrial fibrillation. Several studies have correlated the abnormalities in signal averaged P wave with paroxysmal atrial fibrillation, and have demonstrated its utility in independently predicting patients at risk of developing atrial fibrillation following cardiac surgery. New uses are likely to evolve as the technique is used clinically and as the methodology is standardized.A.N.E. 1999;4(4):401–407
Noninvasive Testing for Selection of Patients for Electrophysiological Study
Authors: Anderson Kelley P. , Shusterman Vladimir , Brode Susan , Gottipaty Venkateshwar , Schwartzman David , Weiss Raul
Published: October 2006

Background:The implantable cardioverter defibrillator (ICD) has underscored the limitations of our methods of risk assessment. ICDs should be available to patients at high risk for arrhythmic death, but because of the potential for adverse effects and high cost it should be scrupulously avoided in patients whose lives will not be prolonged. Unfortunately, discrimination between these two groups of patients remains a challenge. Recent clinical trial results have not only shown that electrophysiological studies (EPS) in combination with other risk stratifiers identify patients with ischemic heart disease at high risk for arrhythmic death, but they have linked the efficacy of ICD therapy to the results of EPS. However, to perform EPS in all potential candidates for ICD therapy would be a time‐consuming and costly burden to medical services and would expose many patients to the risks and discomfort of an invasive procedure. Noninvasive identification of appropriate candidates is therefore essential to successful application of EPS.

Methods:Nonsustained ventricular tachycardia (NSVT) and a reduced left ventricular ejection fraction (EF) was used to select patients for EPS in two important trials, but it is not certain that these are the optimal tests or that the optimal thresholds 1 episode of NSVT 3 beats; EF 0.35 or EF 0.40) were used. A number of studies have addressed the accuracy of clinical factors for predicting the results of EPS and a number of noninvasive tests have been proposed including the signal‐averaged electrocardiogram, heart rate variability, T‐wave alternans, and high spatial resolution (multilead) electrocardiography. In some contexts, combinations of factors provide significant improvements in accuracy. However, the populations studied were often highly selected, which makes comparisons between techniques or prediction of responses in the populations that would require screening difficult. Results from recently completed and ongoing clinical trials should provide important new information. A greater problem is that EPS has not been shown to consistently provide accurate discrimination of patients with nonischemic cardiac disorders.

Conclusions:Effective widespread application of ICD therapy will require greater precision of patient selection. Noninvasive tests under investigation demonstrate considerable promise in selecting appropriate candidates for EPS. However, because the most precise methods of risk assessment are likely to be those most closely linked to the mechanisms of fatal arrhythmias, it is important that further development of noninvasive techniques incorporates advances in basic cardiac electrophysiology. A.N.E. 1999;4(4):434–442
Heart Rate Variability to Assess Changes in Cardiac Vagal Modulation Prior to the Onset of Paroxysmal Atrial Fibrillation in Patients With and Without Structural Heart Disease
Authors: Klingenheben Thomas , Grönefeld Gerian , Li Yi‐Gang , Hohnloser Stefan H.
Published: October 2006

Background and Objectives: In patients with paroxysmal lone AF, clinical data indicate a predominance of vagal modulation preceding attacks of the arryhthmia. Systematic data derived from time‐domain analysis of HRV evaluating changes in autonomic modulation prior to AF onset are sparse, both in patients without and with evidence for structural heart disease. This study evaluated changes in autonomic modulation prior to the onset of AF in patients with and without structural heart disease.

Methods and Results: In 26 consecutive patients with at least one episode of paroxysmal AF preceded by a period of sinus rhythm of at least 8 hours duration documented on Holter monitoring, the time‐domain parameters SDNN, rMSSD, and pNN5O were analyzed at different time points between 8 hours and 10 minutes prior to the onset of AF. Fourteen patients had AF associated with structural heart disease, whereas 12 patients had paroxysmal lone AF. Analysis of HRV changes before onset of AF revealed significant differences between the two patient groups: In patients without heart disease, pNN5O and rMSSD increased from 10 ± 3 to 15 ± 4% (P=0.003) and from 38 ± 7 to 53 ± 9 ms (P=0.035). No significant change in HRV was observed in patients with structural heart disease (pNN5O 5 ± 3 vs. 6 ± 2 % and rMSSD 25 ± 4 vs. 28 ± 6 ms).

Conclusions: In patients with lone AF, there is a significant shift of autonomic modulation towards a vagal predominance prior to the onset of paroxysmal AF as compared to patients with structural heart disease. Analysis of HRV prior to attacks of AF is useful in determining these triggering mechanisms.
Time‐Frequency Analysis of Heart Rate Variability in Hypertension: Clinical and Echocardiographic Associations
Authors: Kudaiberdieva Gulmira Z. , Birand Ahmet , Saliu Sokol
Published: October 2006

Background: Autonomic regulation of heart rate is impaired in hypertensive patients. The aim of this study is to elucidate the relation between HRV measures as assessed in time‐frequency and frequency domains and clinical and echocardiographic features of hypertension with and without left ventricular hypertrophy.

Methods: Forty patients with hypertension were divided into two groups according to gender adjusted echocardiographic signs of left ventricular hypertrophy: group 1–20 patients with hypertension and normal LVMI; group 11–20 patients with hypertension and echocardiographic signs of left ventricular hypertrophy. The control group consists of 20 age‐matched healthy subjects. HRV analysis was accomplished using frequency‐domain analysis (fast Fourier transform) and time‐frequency analysis (smoothed pseudo‐Wigner distribution).

Results: HRV components, very low frequency power (VLFP), low frequency power (LFP), high frequency power (HFP), and total power (TP) were attenuated (P > 0.05) in hypertensive patients with and without left ventricular hypertrophy. LFP/HFP and low frequency related power (LFRP) were markedly higher in group I patients than of group II and controls (P > 0.01, P > 0.0001, and P > 0.001, P > 0.05, respectively). While patients of group II had significantly lower values of VLFP, LFP, LFP/HFP ratio and LFRP as compared with group I patients (P > 0.04, P > 0.0001, P > 0.01, and P > 0.0001, respectively). The burst activity at 0.1 Hz was increased in group I patients while in group II patients it was attenuated. HRV indices associated significantly with cardiac output and systolic blood pressure in patients without signs of left ventricular hypertrophy. In patients with signs of left ventricular hypertrophy, HRV indices correlated with LVMI, related wall thickness, age, and body surface area.

Conclusion: HRV responds differently in different stages of hypertension, with increase response of sinus node to sympathetic influences in hypertension without left ventricular hypertrophy and withdrawal of sympathetic and parasympathetic influences in presence of left ventricular hypertrophy.
P Wave Dispersion: A Valuable Electrocardiographic Marker for the Prediction of Paroxysmal Lone Atrial Fibrillation
Authors: Gialafos John E. , Dilaveris Polychronis E. , Gialafos Elias J. , Andrikopoulos George K. , Richter Dimitrios J. , Triposkiadis Filippos , Kyriakidis Michael K.
Published: October 2006

Background: The prolongation of atrial conduction time and the inhomogeneous propagation of sinus impulses are well known electrophysiological characteristics in patients with paroxysmal atrial fibrillation.

Methods: The aim of this study was to test the ability of a new ECG marker to discriminate between patients with a prior history of paroxysmal lone atrial fibrillation and healthy controls. Maximum P wave duration (Pmax) and the difference between the maximum and the minimum P wave duration, which was defined as P‐wave dispersion (Pdisp) were calculated from the 12‐lead surface ECGs of 75 patients with a history of paroxysmal lone atrial fibrillation and 50 age‐matched healthy controls.

Results: Pmax was in patients 122 ± 17 ms and in controls 101 ± 10 ms (t = 7.935, P > 0.001). Pdisp was in patients 48 ± 16 ms and in controls 29 ± 8 ms (t = 7.616, P > 0.001). A Pmax value of 110 ms separated patients from controls with a sensitivity 85%, a specificity 72%, and a positive predictive accuracy of 82%. A Pdisp value of 40 ms separated patients from controls with a sensitivity of 81%, a specificity of 80%, and a positive predictive accuracy of 85%.

Conclusions: (1) Pmax and Pdisp values were found to be significantly higher in patients with a prior history of paroxysmal lone atrial fibrillation than in age‐matched healthy controls, and (2) Pdisp is a new simple ECG marker that could be possibly used for the identification of patients with a previous history of paroxysmal lone atrial fibrillation. A.N.E. 1999;4(1):39–45
Usefulness of the P Wave Signal‐Averaged Electrocardiogram in Predicting Patients at Risk of Atrial Flutter and Fibrillation Induced by Transesophageal Pacing
Authors: Banasiak Waldemar , Metner Elwira , Owczarek Irena , Fuglewicz Artur , Anker Stefan D. , Kalka Dariusz , Pieróg Miroslaw , Coats Andrew J.S. , Ponikowski Piotr
Published: October 2006

Background: Transesophageal pacing (TEP) may be a useful tool in the evaluation of patients with palpitations. The induction of atrial tachyarrythmia by TEP often allows the detection of an underlying re‐entrant atrial arrhythmia as a cause of the patients' symptoms. Recently, the P‐wave triggered signal‐averaged electrocardiogram (SAECG) has been used to detect patients at risk of paroxysmal atrial tachyarrhythmias. The aim of this study was to investigate the usefulness of the P‐wave triggered SAECG applied in a group of patients with a history of paroxysmal palpitations to identify those prone to the development of electrically‐induced atrial flutter or fibrillation.

Methods: The study population consisted of 46 patients (31 men, mean age 43 ± 11 years) investigated for palpitations with concomitant symptoms of dizziness or presyncope. Patients were divided into 2 groups according to the presence or absence of an atrial arrhythmia induced by TEP. Twenty‐six consecutive patients (18 men, mean age 44 ± 13 years) demonstrated electrically‐inducible, sustained (lasting < 30 s) atrial fibrillation or atrial flutter (arrhythmia group). The control group comprised 20 patients (13 men, mean age 44 ± 9 years) with similar symptoms, but without significant atrial arrhythmia induced by TEP. The following P‐wave triggered SAECG indices were calculated: the root mean square voltage for the terminal 10, 20, 30 ms of the filtered P‐wave (RMS10,20,30) and time duration of the filtered P‐wave (PWD).

Results: Patients with atrial fibrillation or flutter induced by TEP demonstrated significantly longer values of the PWD compared to controls (126.5 ± 15.9 ms vs. 108.0 ± 7.0 ms respectively, P > 0.0001). In the former group we also found the decreased voltage of the terminal part of the P‐wave: RMS10 (4.1 ± 1.1 ptV vs 5.5 ± 2.1 pV, P = 0.002), RMS20 (5.1 ± 1.4 μ V vs. 7.3 ± 2.6 μ V, P = 0.0007), and RMS30 (6.2 ± 1.8 μ V vs. 8.7 ± 2.5 μ V, P = 0.0003) (all comparisons arrhythmia group vs controls, respectively). Moreover, a value of PWD < 117 ms appeared to have practical value in the detection patients at risk of atrial fibrillation or flutter induced by TEP, with a specificity of 90%, sensitivity of 77%, and positive predictive value of 91%.

Conclusion: We conclude that among patients presenting with paroxysmal palpitations the P‐wave triggered SAECG had practical value as an noninvasive method to identify those at risk of electrically‐inducible atrial fibrillation and flutter. To what extent this could improve the management of these patients merits further evaluation. A.N.E. 1999;4(1):46–52
Double‐Blind Comparison of Cibenzoline Versus Flecainide in the Prevention of Recurrence of Atrial Tachyarrhythmias in 139 Patients
Authors: Babuty D. , Maison‐Blanche P. , Fauchier L. , Brembilla‐Perrot B. , Medvedowsky J.L. , Bine‐Scheck F.
Published: October 2006

Background: The efficacy and safety of antiarrhythmic drugs for the prevention of atrial arrythmias are controversial because previous studies were nonrandomized or involved nonselected patients. The aim of this study was to evaluate the efficacy and tolerance of two Class I antiarrythmic drugs, cibenzoline, and flecainide, for the treatment of atrial arrhythmias in carefully selected patients.

Patients and Methods: One hundred thirty‐nine patients suffering from documented atrial arrhythmias (mean age 63 ± 12 years, 80 males, 59 females) were enrolled in randomized, double‐blind, parallel clinical trials. Seventy patients received cibenzoline and 69 received flecainide; they were followed for a period of 6 months. All patients had good systolic ventricular function. The recurrence of atrial arrhythmias was diagnosed on symptoms, resting ECG, and 24‐hour ambulatory ECG 3 and 6 months after commencing treatment.

Results: Twenty‐seven patients were withdrawn during the study, 13 for adverse side effects, 4 for proarrhythmic effects, and 3 for medical events; 7 were lost to follow‐up. Forty‐three patients had one recurrence of atrial arrhythmias (23 in the cibenzoline group, 20 in the flecainide group). The cumulative percentage of patients free from recurrence was not significantly different in either group at 6 months (63.7% in the cibenzoline group and 66.8% in the flecainide group). Cardiac adverse side effects were more frequent with flecainide than cibenzoline (5 vs. 2). One atrial proarrhythmic effect was observed.

Conclusion: Cibenzoline and flecainide are both Class I antiarrhythmic agents which are well tolerated and may be safely administered to prevent alrial arrhythmias. A.N.E. 1999;4(1):53–59
Right Ventricular Dysplasia: A Report of 24 Adult Cases
Authors: MARCUS FRANK I. , FONTAINE GUY H. , GUIRAUDON GERARD , FRANK ROBERT , LAURENCEAU JEAN L. , MALERGUE CHRISTINE , GROSGOGEAT YVES
Published: October 2006

Right ventricular dysplasia is characterized by an abnormality in the development of part of the right ventricular musculature. Patients with right ventricular dysplasia may present with ventricular tachycardia, suprgventricular arrhythmias, right‐heart failure or asymptomatic cardlomegaly. Twenty‐two adult patients with right ventricular dysplasia who had recurrent ventricular tachycardia were seen during a 7‐year period. The male/female ratio was 2.7:1. The mean age at the time of hospitalization was 39 years. All but one of the patients had ventricular tachycardia of a left bundle branch block configuration. With few exceptions, the T waves were inverted over the right precordial leads. The heart was usually enlarged and the pulmonary vasculaturc was usually normal. In six patients who had two‐dimensional echocardiograms, all showed increased right ventricular diastolic dimensions. All patients had right ventricular angiography; the diagnosis of right ventricular dysplasia was substantiated during surgery in 12 patients and at autopsy in another. Two other patients who did not have arrhythmias had right ventricular dysplasia diagnosed by right‐ and left‐heart angiography.

Our unique experience, when combined with a literature review of 34 adult cases, permits a composite clinical profile of this condition in the adult.
Wavelet Analysis of Signal‐Averaged Electrocardiograms
Authors: Malik Marek , Hnatkova Katerina , Staunton Anne , Camm A. John
Published: October 2006

Background:Spectral techniques for the analysis of signal‐averaged electrocardiogram (ECG) are superior to the standard time‐domain analysis in special circumstances but none of these techniques is better than the time‐domain analysis in the prospective risk stratification of survivors of myocardial infarction (Ml).

Aim:This study applied wavelet decomposition of signal‐averaged ECGs to prospective risk stratification of Ml survivors and compared its performance with that of conventional time‐domain analysis.

Methods:Eligible patients were aged 75 years without atrial fibrillation, important noncardiac disease, bundle branch block, ventricular preexcitation, permanent pacemaker, or a history of cardiac surgery. Of 754 eligible patients, signal‐averaged ECG recordings were available in 551. During a 2‐year follow‐up, 32 patients suffered from cardiac death (CM), 21 potentially arrhythmic death, 19 sudden cardiac death (SCO), 19 developed nonfatal sustained ventricular tachycardia (VT), and 5 were resuscitated from an ECG‐documented ventricular fibrillation. Signal‐averaged ECG indices from both analyses were compared in patients with and without different follow‐up events. The positive predictive characteristics (dependency of positive predictive accuracy on sensitivity) for predicting different follow‐up events based on both modes of analysis were compared at selected levels of sensitivity.

Results: Time‐domain signal‐averaged ECGs were strongly correlated with incidence of VT (P = 0.01). Positive wavelet analysis was more strongly correlated with this event (P < 0.005) and with cardiac mortality (P < 0.05). For all events, wavelet analysis gave higher positive predictive accuracy (PPA) than the time‐domain analysis, e.g., the prediction of SCD at sensitivity of 25%, wavelet and time‐domain analyses gave PPA of 20.0% and 6.5%, respectively (P < 10‐10).

Conclusion:Wavelet decomposition analysis of signal‐averaged ECGs is superior to the standard time‐domain analysis in predicting post‐MI events. In particular, this analysis identifies not only those post‐MI patients who are at high risk of nonfatal sustained VT but also those who are at risk of SCD. A.N.E. 2000;5(1):20–29
Autonomic Nerve Tone After an Eastward Transmeridian Flight as Indicated by Heart Rate Variability
Authors: Tateishi Osamu , Nogimura Takeshi , Honda Youichi , Goto Yutaka , Chin Keiichi , Itou Tetsushi , Mochizuki Seibu , Fujishiro Kentarou
Published: October 2006

Background:Transmeridian flights commonly cause the physical distress and somnolence known as jet lag. Because the influence of jet lag on autonomic nerve tone (ANTi is unclear, we studied its influence by evaluating heart rate variability before versus after a flight from Tokyo to San Francisco.

Methods:We recorded the ambulatory electrocardiograms of 12 healthy young men for 11 days, i.e., 3 days in Tokyo before the flight and 8 days in San Francisco following the flight. Heart rate variability was determined by power spectrum analysis. After calculating high frequency power (0.15–0.4 Hz, HF), low frequency power (0.04–0.15 Hz, LF), and LF/HF, we evaluated autonomic nerve tone using HF and LF/HF as indices of the activity of sympathetic and parasympathetic tone, respectively. In addition, we analyzed the circadian rhythm of autonomic nerve tone by the maximum entropy method.

Results:Parasympathetic nerve tone was found to increase during the flight. The time required for the ANT to return to preflight levels differed between the waking and sleeping periods, being 5 and 7 days, respectively.

Conclusions: ANT varied for 1 week after an eastward transmeridian flight. A.N.E. 2000;5(1):53–59
Utility of an Accelerometer Sensor Integrated into a Holter Monitoring System
Authors: Fotuhi Parwis , Combs William , Sheldon Todd , Theres Heinz , Stangi Karl , Baumann Gert
Published: October 2006

Background:Patients routinely undergo Holter monitor evaluation for the detection of cardiac arrhythmias. Documentation of daily patient activities is a common shortcoming. Discriminating physiological from pathological heart rate, e.g., sinus tachycardia in response to exercise from supraventricular tachyarrhythmia, can be difficult without an accurate diary. Independent documentation of body activity may help solve this inadequacy. Accelerometer‐based pacing systems have established the utility of general body activity detection for pacemaker rate determination.

Methods:An accelerometer sensor was positioned in the left pectoral region in 10 volunteers for measurement of normal daily subject activity. Additionally, the volunteers were asked to keep a detailed diary of daily activities. The accelerometer sensor signal was recorded on one channel of a modified Holter monitor system. The Holter FCG and accelerometer data were analyzed and compared to the detailed diary. The study was then repeated in 10 patients undergoing standard Holter monitor evaluation.

Results:In all 20 subjects, reviewing the 24‐hour profiles allowed correlation of heart rate response to activities such as walking, resting, exercise, or sleep and the accelerometer sensor signal. In the patients, a total of 170 minutes of increased heart rate correlated with documented physical activity, while 14 minutes did not. Additionally, 161 minutes of bradycardia during physical activity were also identified.

Conclusion:Present‐day Holter systems can detect bradycardias and tachycardias based on ECG characteristics and rate criteria. The addition of acceterometer signal to standard Holter ECG might improve physician interpretation of patient heart rate response to daily patient activities. A.N.E. 2000;5(1):73–78
The Development of the Transvenous Automatic Defibrillator
Authors: Mirowski M. , Mower Morton M. , Staewen William S. , Denniston Rollin H. , Mendeloff Albert I.
Published: October 2006

The transvenous automatic defibrillator is a device which automatically recognizes and treats ventricular fibrillation. The initial clinical prototype resembles an external pacemaker: the electronic components and power supply are external to the body, the sensing and defibrillating elements being contained in a transvenous catheter. The sensors monitor intracardiac R waves and cardiac contraction. Absence of both signals identifies the arrhythmia and triggers the defibrillatory shock, delivered through the right ventricular electrode and another more proximal on the catheter. If needed, the device recycles automatically. It is also adaptable for pacing and for elective intraatrial cardioversion. Results of animal experiments were successful, and tests are currently being done on patients requiring defl‐brillation during open heart surgery. The clinical indications for the device are numerous and it is hoped that this approach will decrease the present prohibitive mortality from coronary heart disease.
Diagnostic Value of Exercise‐Induced ST‐Segment Elevation in Q‐Wave Leads. After Recent Myocardial Infarction
Authors: Zielinska Marzenna , Koniarek Wlodzimierz , Bolinska Halina , Maciejewski Marek
Published: October 2006

Background: Exercise‐induced ST‐segment elevation in an infarct territory with abnormal Q waves is a known marker for more severe left ventricular wall‐motion abnormalities. However, it is reported, that exercise‐induced ST‐segment elevation in infarct leads may indicate residual viability in the intarctregion. The aim of the study was to test whether exercise‐induced ST‐segment elevation is related to left ventricular (LV) dysfunction or to persistent viability in patients with previous myocardial infarction (MI).

Methods: 145 consecutive patients (119 men, 26 women, age 58 ± 11 years) 2–3 weeks after Q‐wave Ml but without ST elevation at rest ECG were enrolled in the study. All patients underwent a target heart rate or symptom‐limited exercise testing (ET) with Bruce protocol. Exercise‐induced ST‐segment elevation < 1 mm above the baseline ST segment level (80 ms after J point) in more than 1 ECG lead with Q wave was considered to be significant. Patients were divided in two groups according to ET results: group I, 25 patients with significant exercise‐induced ST‐segment elevation and group II, 120 patients without exercise‐induced ST‐segment elevation. All patients underwent rest ECHO and low dose dobutamine stress echo (LOSE) within 7 days after ET. LV function was estimated using ejection fraction (EF).

Results: More severe LV dysfunction was observed in patients from group 1 (EF 31 ± 8.16% vs EF 45 ± 10.3%). Myocardial viability (defined as an improvement of regional systolic wall thickening in the regions with resting regional wall‐motion abnormalities during LOSE 5 to 15 g/kg/min was recognized in 8 patients (32%) in group I and 31 patients (25.8%) in group II. There was no relation between exercise‐induced ST‐segment elevation and myocardial viability (chi‐square test: 2,809; NS).

Conclusions: Exercise‐induced ST‐segment elevation in most cases is associated with left ventricular dysfunction. Patients with exercise‐induced ST‐segment elevation have a lower EF than those without and greater severity of resting wall‐motion abnormalities. Our results suggest that exercise‐induced ST‐segment elevation is not related to residual myocardial viability.
Heart Failure and Cardiac Resynchronization Therapies: U.S. Experience in the Year 2000
Authors: Saxon Leslie A. , Kumar Uday N. , De Marco Teresa
Published: October 2006

Controlled U.S. trials of cardiac resynchronization therapy (CRT) for improvement of heart failure status are in progress. This article provides the current year 2000 status of all clinical trials in the United States evaluating CRT with and without an ICD.
Exercise QT Dispersion as an Independent Predictor of the Presence of Ischemia on Myocardial Perfusion Imaging
Authors: Morise Anthony P. , Beto Robert , Gupta Naresh , Gunel Erdogan
Published: October 2006

Background: Increased QT dispersion on resting electrocardiography has been shown to be related to ischemia and to predict adverse cardiac events. The purpose of the present study was to evaluate the relationship between myocardial ischemia and the exercise QT dispersion response.

Methods: We studied 368 patients with normal resting electrocardiograms referred for exercise SPECT myocardial perfusion scintigraphy because of suspected coronary disease. We used signal‐averaged recordings of 12‐lead electrocardiograms to manually measure QT dispersion at rest and peak exercise. We interpreted scintigrams visually as ischemic or nonischemic.

Results: The 49 patients with scintigraphic ischemia were compared to the 319 patients without ischemia. Resting QT dispersion did not differ, but exercise QT dispersion was significantly greater in those with ischemia (25 ± 13 ms vs 32 ± 15 ms; P = 0.0004). Using logistic regression analysis with any ischemia present or absent as the dependent variable, exercise QT dispersion was an independent predictor (P = 0.0006) of the presence of ischemia. We also found a significant increase in receiver operating characteristic curve area when exercise QT dispersion was included in the model (areas 0.74 ± 0.04 vs 0.78 ± 0.03; P = 0.035). Exercise QT dispersion as a dependent variable was independently associated with sex (increased in women) and perfusion ischemia (positive relation).

Conclusion: Exercise QT dispersion is an independent predictor of the presence of scintigraphic ischemia that has incremental value over other clinical and exercise test variables.
Ectopic Beats in Heart Rate Variability Analysis: Effects of Editing on Time and Frequency Domain Measures
Authors: Salo Mirja A. , Huikuri Heikki V. , Seppanen Tapio
Published: October 2006

Background: Various methods can be used to edit biological and technical artefacts in heart rate variability (HRV), but there is relatively little information on the effects of such editing methods on HRV.

Methods: The effects of editing on HRV analysis were studied using R‐R interval data of 10 healthy subjects and 10 patients with a previous myocardial infarction (Ml). R‐R interval tachograms of verified sinus beats were analyzed from short‐term (∼5 min) and long‐term (—24 hours) recordings by eliminating different amounts of real R‐R intervals. Three editing methods were applied to these segments: (1) interpolation of degree zero, (2) interpolation of degree one, and (3) deletion without replacement.

Results: In time domain analysis of short‐term data, the standard deviation of normal‐to‐normal intervals (SDANN) was least affected by editing, and 30%‐50% of the data could be edited by all the three methods without a significant error (< 5%). In the frequency domain analysis, the method of editing resulted in remarkably different changes and errors for both the high‐frequency (HF) and the low‐frequency (LF) spectral components. The editing methods also yielded in different results in healthy subjects and AMI patients. In 24‐hour HRV analysis, up to 50% could be edited by all methods without an error larger than 5% in the analysis of the standard deviation of normal to normal intervals (SDNN). Both interpolation methods also performed well in the editing of the long‐term power spectral components for 24‐hour data, but with the deletion method, only 5% of the data could be edited without a significant error.

Conclusions: The amount and type of editing R‐R interval data have remarkably different effects on various HRV indices. There is no universal method for editing ectopic beats that could be used in both the time‐domain and the frequency‐domain analysis of HRV. A.N.E. 2001;6(1):5–17
Reproducibility of QT Parameters Derived from 24‐hour Ambulatory ECG Recordings in Healthy Subjects
Authors: Arildsen Hanne , Christiansen Evald Høj , Pedersen Anders Kirstein , Møgaard Henning
Published: October 2006

Aim: To estimate the reproducibility of QT parameters derived from 24‐hour ambulatory ECG recordings.

Method: Ten healthy volunteers aged 25 to 41 years participated. In two 24‐hour ambulatory ECG recordings obtained 1 day apart, the QT interval was measured manually at stable heart rates in approximately 16 periods during daytime and 6 periods during nighttime. The association between the QT and RR interval was described by linear regression for day and nighttime separately and the following QT parameters were calculated: the QT interval at heart rate 60 beats/min during daytime (QT(60)day), slope(day), slope(night), and the difference in QT(60) between day and nighttime (ΔQT(60)). The QT parameters were assessed four times for each participant to discriminate method inaccuracy from day to day variation. The reproducibility was estimated as the coefficient of repeatability, the relative error, and the ratio between within‐subject variability and between‐subject variability.

Results: The coefficient of repeatability, the relative error and the ratio, respectively, were 19 ms, 1.8% and 0.5 for QT(60)day, 0.076, 21% and 0.68 for slope(day), 0.116, 43% and 1.37 for slope(night), and 37 ms, 325% and 1.19 for ΔQT(60) when estimating the overall day to day reproducibility. Inaccuracy of QT measurement accounted for approximately 40% of this variation, whereas the error caused by selecting segments was small.

Conclusion: QT(60)day has a high reproducibility and may with advantage replace the conventional QT interval measured on a resting ECG. To assess QT dynamics, the slope of the regression line during daytime is suitable and the short term reproducibility acceptable for clinical trials. Regarding slope(night) and ΔQT(60), the variation is high and the parameters should be used with caution. A.N.E. 2001;6(1):24–31
Computerized ST Depression Analysis Improves Prediction of All‐Cause and Cardiovascular Mortality: The Strong Heart Study
Authors: Okin Peter M. , Devereux Richard B. , Kors Jan A. , van Herpen Gerard , Crow Richard S. , Fabsitz Richard R. , Howard Barbara V.
Published: October 2006

Background:Nonspecific ST depression assessed by standard visual Minnesota coding (MC) has been demonstrated to predict risk. Although computer analysis has been applied to digital ECGs for MC, the prognostic value of computerized MC and computerized ST depression analyses have not been examined in relation to standard visual MC.

Methods:The predictive value of nonspecific ST depression as determined by visual and computerized MC codes 4.2 or 4.3 was compared with computer‐measured ST depression ≧ 50 μV in 2,127 American Indian participants in the first Strong Heart Study examination. Computerized MC and ST depression were determined using separate computerized‐ECG analysis programs and visual MC was performed by an experienced ECG core laboratory.

Results:The prevalence of MC 4.2 or 4.3 by computer was higher than by visual analysis (6.4 vs 4.4%, P < 0.001). After mean follow‐up of 3.7 ± 0.9 years, there were 73 cardiovascular deaths and 227 deaths from all causes. In univariate Cox analyses, visual MC (relative risk [RR] 4.8,95% confidence interval [CIJ 2.6–9.1), computerized MC (RR 6.0, 95% Cl 3.5–10.3), and computer‐measured ST depression (RR 7.6, 95% CI 4.5–12.9) were all significant predictors of cardiovascular death. In separate multivariate Cox regression analyses that included age, sex, diabetes, HDL and LDL cholesterol, body mass index, systolic and diastolic blood pressure, microalbuminuria, smoking, and the presence of coronary heart disease, computerized MC (RR 3.0, 95% Cl 1.6–5.6) and computer‐measured ST depression (RR 3.1, 95% Cl 1.7–5.7), but not visual MC, remained significant predictors of cardiovascular mortality. When both computerized MC and computer‐measured ST depression were entered into the multivariate Cox regression, each variable provided independent risk stratification (RR 2.1, 95% Cl 1.0–4.4, and RR 2.1, 95% CI 1.0–4.4, respectively). Similarly, computerized MC and computer‐measured ST depression, but not visual MC, were independent predictors of all‐cause mortality after controlling for standard risk factors.

Conclusions:Computer analysis of the ECG, using computerized MC and computer‐measured ST depression, provides independent and additive risk stratification for cardiovascular and all‐cause mortality, and improves risk stratification compared with visual MC. These findings support the use of routine computer analysis of ST depression on the rest ECG for assessment of risk and suggest that computerized MC can replace visual MC for this purpose. A.N.E. 2001;6(2):107–116