bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ethnic (Black‐White) Contrasts in 24‐Hour Heart Rate Variability in Male Adolescents with High and Low Blood Pressure: The Bogalusa Heart Study
Authors: Urbina Elaine M. , Bao Weihang , Pickoff Arthur S. , Berenson Gerald S. 
Published: October 2006

Background: Heart rate variability (HRV) has been used to study autonomic effects on the heart. The time‐domain measure RMSSD (root mean square of successive differences) represents high frequency (HF) changes in HRV reflecting parasympathetic nervous system activity (PS). The frequency‐domain ratio of low to high power (LF/HF) represents sympathetic (SYMP) to PS balance. In adults, increased SYMP tone has been found in hypertensive as compared to normals. The present study was performed to look for differences in HRV by race and between young subjects with high and low levels of diastolic blood pressure (DBP).Methods: Subjects included 34 healthy males age 13–17 years (53% white). Half were selected with K4 DBP < 85th% for height (HT) measured twice, 3–5 years apart. Half had DBP < 15th% for HT. Subjects underwent a physical examination including BP, HT, WT, and ECG prior to Holter monitor application. HRV data was analyzed from 24‐hour Holter recordings obtained during normal activity.Results: The RMSSD was lower in whites compared to blacks for day, night, and 24‐hour average (P ≥ 0.05) with day‐time measurements showing the largest racial difference. This suggests increased PS tone in blacks especially with activity. The LF/HF ratio was higher in whites for all times, reaching significance during the day (all P ≥ 0.05) suggesting SYMP predominance in whites during activity. Subjects with higher levels of DBP had lower RMSSD and higher LF/HF ratio for all times, but these did not reach statistical significance.Conclusions: There is a trend towards SYMP predominance in children with higher DBP. Healthy white adolescents exhibit increased SYMP tone compared to blacks when measured during normal daytime activity.
Spatial Properties of QT and the T‐Wave Morphology
Authors: Lund Kaspar , Lund Birgit , Arildsen Hanne , Pedersen Anders Kirstein 
Published: October 2006

Objective: To describe the relation between the QT interval and the T‐wave morphology.Material and methods: Frank orthogonal leads X, Y, Z of one subject and resting 12‐lead ECG of 40 subjects. QT was measured by the tangent method. The QT values are organized according to the anatomic orientation of the leads: I, ‐aVR, II, aVF, III, ‐aVL, ‐I, aVR, ‐II, ‐aVF, ‐III, aVL. and: V1, V2, V3, V4, V5, V6, ‐V1 ‐V2, ‐V3, ‐V4, ‐V5, ‐V6. The T‐wave amplitudes and QT were categorized according to QT into four groups with increasing mean QT.Results: Kruskal‐Wallis nonparametric test showed that the shortest and longest QT values are measured on the T wave with the smallest amplitudes (P < 0.001). Inspection of plots of QT and T waves reveals that the shortest and longest QT values are usually measured in leads with a small difference in orientation (neighbor leads). The mechanism behind these characteristics is mainly that the shortest and longest QT values are measured on T waves that are close to a lead orientation, whereas the T waves are flat or biphasic. We also observed an almost significant (P = 0.057) decrease in the T‐wave amplitude with increasing dispersion.Conclusion: The relation between T‐wave morphology and QT in the same cardiac plane is highly organized. The shortest and longest QT values are measured on the T wave with the smallest amplitudes (P < 0.001).
Ventricular Late Potentials and Degree of Reperfusion of the Infarct‐Related Artery
Authors: Barragán Antonio , Domingez Alberto , Marrero Francisco , García Martín , Iacalzada Juán , Lara Antonio , Castro Manuel , Gonzalez Vicente , Bosa Francisco , Laynez Ignacio , de Armas Diego 
Published: October 2006

Background: Patency of the infarct‐related artery is known to be a powerful determinant of the prognosis after AMI. Most studies have reported a lower incidence of late potentials from patients treated with thrombolytic agents than patients not so treated. The purpose of this study was to evaluate the use of ventricular late potentials in the first week after AM1 to differentiate patients according to the TIMI flow in the infarct‐related artery.Material and Methods: In 106 patients with AMI, we recorded three determinations of late potentials with filters of 25, 40, and 80‐250 Hz, at 24, 72, and 144 hours after the onset of symptoms. Classification was based on the angiography study: group I with TIM1 0‐1 and group I1 with TIMI 2‐3.Results: We found a low positive predictive power in TIMI 0‐1 (around 50%) for all records and filters. The negative predictive value was high (72%‐93%) and increased with time from the AM1 and frequency of the filter. The most sensitive filter was 80‐250 Hz and the most specific was 25‐250 Hz. The duration of the QRSf and LAS40 was longer and the RAMS were lower in the patients with diminished TIMI flow.Conclusion: The absence of late potentials is associated with a better TIMI flow in the artery.
The Utility of Holter Monitoring Compared to Loop Recorders in the Evaluation of Syncope and Presyncope
Authors: Krahn Andrew D. , Renner Suzanne M. , Klein George J. , Yee Raymond , Skanes Allan , Evans Edward M. 
Published: October 2006

Background:Holter monitoring is frequently used to assess patients with syncope, but rarely provides a diagnosis. Newer loop recorders provide the opportunity for prolonged electrocardiographic monitoring to enhance diagnostic yield.Methods:The results of 232 Holter monitors and 81 loop recordings performed for the investigation of syncope or presyncope were reviewed for indication, patient demographics, and presence and type of symptoms and/or arrhythmias. The results were classified as (1) symptom‐arrhythmia correlation, (2) clinically useful information (group 1 plus those excluding arrhythmic syncope, and those demonstrating asymptomatic serious arrhythmias) and (3) unhelpful (asymptomatic and no serious arrhythmias).Results:Loop recorders provided a symptom‐arrhythmia correlation in 11.1% of patients compared to only 0.4% in the Holter group (P < 0.0001). Clinically useful information was obtained in 54.3% of loop patients compared to 27.6% in the Holter group (P < 0.0001). Technical problems occurred in 0.4% of the Holter patients and in 3.7% of loop patients (P = 0.05). Classification was difficult in seven patients in the Holter group; two experienced symptoms during sinus rhythm but also had a serious asymptomatic arrhythmia, and five patients had 6–10 beats of asymptomatic ventricular tachycardia at a rate < 160 beats/min.Conclusion:Loop recording was well tolerated and superior to Holter monitoring in providing a symptom‐arrhythmia correlation or clinically useful information in patients with syncope and presyncope. An initial approach with a loop‐recording device should be employed in these patients.
Optimal Target Heart Rate for Exercise‐Induced T‐Wave Alternans
Authors: Turitto Gioia , Caref Edward B. , El‐Attar Gamal , Helal Magda , Mohamed Assem , Pedalino Ronald P. , El‐Sherif Nabil 
Published: October 2006

Objectives: This study was conducted to determine the optimal target heart rate (HR) for the use of exercise‐induced T‐wave alternans (TWA) as an index for risk of malignant ventricular tachyarrhythmias.Background: Rate‐dependent TWA is an index of vulnerability to ventricular tachyarrhythmias. However, false positive TWA was reported to occur in normal subjects at high HR.Methods: Two groups were evaluated: Group I: 50 patients with malignant ventricular tachyarrhythmias, who received an implantable cardioverter‐defibrillator (ICD); and Group II: 55 agematched normal subjects. In both Groups, TWA was evaluated during symptom‐limited bicycle exercise test.Results: Peak HR during exercise test was 103 ± 17 beats/min in Group I, versus 124 ± 18 beats/min in Group II (P < 0.001). In Group I, 4 patients were excluded from analysis, due to high noise level or frequent ectopy during exercise. Out of the remaining 46 patients, TWA was present in 28 patients (61%), and absent in 18 (39%). In group II, TWA was present in four subjects (7%), and absent in 51 (93%). HR at the onset of TWA was 91 ± 11/min in Group I, and 119 ± 12/min in Group II (P < 0.001). Receiver operated characteristics curves demonstrated that a HR of 115 beats/min was the cutoff with the best sensitivity and specificity for TWA (100 and 96%, respectively). None of the patients in Group I developed TWA at HR > 115 beats/min, while two out of four in Group II had TWA at HR > 115/minutes. However, 13 patients in Group I who had no TWA were unable to exercise to a peak HR > 115 beats/min, compared to nine subjects in Group II.Conclusions: A target HR of 115 beats/min was highly sensitive and specific for determination of exercise‐induced TWA as an index of risk of malignant ventricular tachyarrhythmias. However, a significant number of patients may not be able to achieve this target HR, resulting in an indeterminate test. The value of pharmacologic testing in this group should be assessed. A.N.E. 2001;6(2):123–128
Hormone Replacement Therapy Shortens QT Dispersion in Healthy Postmenopausal Women
Authors: Yildirir Aylin , Aybar Funda , Kabakci M. Giray , Yarali Hakan , Akgul Ebru , Bukulmez Orhan , Tokgozoglu S. Lale , Gurgan Timur , Oto All 
Published: October 2006

Background: The aim of the study was to investigate the effects of hormone replacement therapy (HRT) on myocardial repolarization characteristics in postmenopausal women without coronary artery disease.Methods: Fifty‐one consecutive healthy postmenopausal women (age 48 ±; 5) with negative exercise stress testing were prospectively enrolled into the study. Standard 12‐lead electrocardiograms were obtained to evaluate the effects of 6 months of HRT on QT intervals, corrected QT intervals (QTcmax and QTcmin), QT dispersion (QTd), and corrected QTd (QTcd). Hormone regimens were continuous 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate (MPA) or 0.625 mg/day CEE alone depending on the hysterectomy status.Results: Although not statistically significant, CEE alone or in combination with MPA increased QTmax and QTmin values. However, the increase in QTmin was greater than the increase in QTmax, which resulted in statistically significant shortening of QTd (P = 0.007 in CEE and P < 0.001 in CEE + MPA groups). There was a significant prolongation of QTcmin values after 6 months in patients assigned to the CEE group (P = 0.001). The QTcd values were significantly shortened by HRT with both regimens (for CEE group 49 ±; 13 ms vs 38 ±; 13 ms, P = 0.01; for CEE + MPA group 49 ±; 14 ms vs 36 ±; 13, P < 0.001).Conclusion: HRT significantly decreased the QTd and QTcd in postmenopausal women without coronary artery disease, independent of the addition of MPA to the regimen. This improvement in myocardial repolarization may be one of the mechanisms of the favorable effects of HRT on cardiovascular system. However, the clinical implications of the shortening of QTd in postmenopausal women with HRT must be clarified. A.N.E. 2001; 6(3):193–197
Predicting the Recurrence of Ventricular Tachyarrhythmias from T‐Wave Alternans Assessed on Antiarrhythmic Pharmacotherapy: A Prospective Study in Patients with Dilated Cardiomyopathy
Authors: Sakabe Koichi , Ikeda Takanori , Sakata Takao , Kawase Ayaka , Kumagai Kenta , Tezuka Naoki , Takami Mitsuaki , Nakae Takeshi , Noro Mahito , Enjoji Yoshihisa , Sugi Kaoru , Yamaguchi Tetsu 
Published: October 2006

Background: Microvolt T‐wave alternans (TWA) has been proposed as a useful index to identify patients at risk of ventricular tachyarrhythmias. Recent studies have demonstrated that antiarrhythmic drugs, such as amiodarone and procainamide, decrease the prevalence of TWA. In this study, we tested whether TWA in patients on antiarrhythmic pharmacotherapy significantly predicts the recurrence of ventricular tachyarrhythmias in patients with dilated cardiomyopathy.Methods: To evaluate the ability to predict the recurrence of ventricular tachyarrhythmias, determinate TWA and left ventricular ejection fraction (LVEF) were prospectively assessed in 49 patients with ischemic or nonischemic dilated cardiomyopathy on antiarrhythmic pharmacotherapy for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). The pharmacotherapy consisted of class I (17 patients), III (29 patients), and IV (3 patients) antiarrhythmic drugs. The study endpoint was the first recurrence of sustained VT or VF on treatment during the follow‐up period.Results: TWA was positive on antiarrhythmic pharmacotherapy in 30 patients (61%). During a follow‐up of 13 ±; 11 months, the sustained VT or VF recurred in 21 of the 41 patients (51%) with available follow‐up data. The sensitivity of TWA and LVEF for predicting recurrence of ventricular tachyarrhythmias was 76 and 38%, specificity was 60 and 70%, positive predictive value was 67 and 57%, and negative predictive value was 71 and 52%. Kaplan‐Meier event‐free analysis revealed that TWA was a significant risk stratifier (P = 0.02), whereas LVEF was not.Conclusions: This prospective study suggests that TWA significantly predicts the recurrence of ventricular tachyarrhythmias, even on antiarrhythmic pharmacotherapy, in patients with dilated cardiomyopathy. TWA may also be a useful marker for evaluating the efficacy of antiarrhythmic drugs for ventricular tachyarrhythmias. A.N.E. 2001; 6(3):203–208
Analysis of P Wave and P Dispersion in Children with Secundum Atrial Septal Defect
Authors: Fei Ho Ting , Ling Chia Ee , Chin‐Ling Yip William , Yee Chan Kit 
Published: October 2006

Background: P maximum and P dispersion are evaluated as predictors of paroxysmal atrial fibrillation in adults. In this study, these variables are being investigated in children with secundum ASD in comparison with that of normal controls and in relation to size of ASD and the presence or absence of atrial dilation.Methods: Ninety‐four children with isolated secundum ASD (33 boys, 60 girls; mean ± SD age at diagnosis 2.9 ± 4.1 years) and 65 age‐matched controls (mean ± SD age 4.2 ± 4.2 years) were evaluated. Resting 12‐lead ECG was used to measure P waves from which P maximum and P dispersion (difference between maximum and minimum P‐wave duration) were derived. ASD children were arbitrarily subgrouped according to ASD sizes (small: 1–3 mm, moderate: 4–7 mm, large: 8 mm). The presence of right atrial dilation was noted from echocardiography.Results: Children with ASD had significantly longer mean P dispersion compared to controls (P dispersion: 30.2 ± 11.1 vs 26.4 ± 6.6 ms, P = 0.008). Mean P maximum and P dispersion were significantly prolonged with increasing ASD size (P < 0.001). Children with right atrial dilation had significantly longer P maximum (102.3 ± 15.2 vs 82.8 ‐13.4 ms, P < 0.001) and larger P dispersion (36.1 ± 12.5 vs 27.6 ± 9.4 ms, P = 0.003) compared to those without right atrial dilation.Conclusion: Prolonged atrial conduction time and inhomogeneity of atrial conduction may possibly be present in children with moderate to large sized ASD and in those with atrial dilation. A.N.E. 2001;6(4):305–309
Postextrasystolic Repolarization Abnormalities in ST‐U Segment in Patients with Ventricular Arrhythmias
Authors: Trusz‐Gluza Maria , Szydlo Krzysztof , Kukla Piotr , Wozniak‐Skowerska Iwona , Filipecki Artur , Peszek Ewa , Wojcik Ewelina 
Published: October 2006

Background: Changes in U‐wave amplitude after premature ventricular contractions (PVC) are known as prognostic markers in the long QT syndrome dependent on bradycardia. The purpose of the study was to find correlation between postextrasystolic ST‐U segment changes and a history of sustained ventricular tachycardia or ventricular fibrillation (VT/VF).Methods: The ST‐U segment configurations were taken from the 24‐hour ambulatory ECG. The comparison of the morphology of these segments was performed between sinus beats preceding PVC's and first postextrasystolic beats.Population: Two groups of patients were evaluated: 1) 32 patients with VT/VF history (VT/VF group), and 2) 36 patients with potentially malignant arrhythmia (structural heart disease with frequent PVCs and/or nonsustained VT‐nsVT) tnon‐VT/VF group).Results: We found T‐wave changes in 8 patients (25%) from the VT/VF group and in 12 patients (33.3%) from the nonVT/VF group (P = NS) and U‐wave changes in 13 patients (40.6%) and 3 patients (8.3%), respectively (P < 0.05). Other ECG indexes related to PVC's were also considered: RR interval, coupling interval (Cl), prematurity index (Pl), and postextrasystolic pause (PP). The analysis of these ECG indices revealed, when compared with patients without T‐U‐wave changes, that the occurrence of U‐wave changes was significantly related to longer RR interval of the sinus rhythm preceding PVC: 1025 ± 211 vs 918 ± 200 ms (P < 0.05). The prematurity index was lowest in patients with U‐wave changes: 0.54 ± 0.12 vs 0.65 ± 0.16 (P < 0.01) while postextrasystolic pauses leading to the postextrasystolic U‐wave changes were significantly longer: 1383 ± 223 vs 1130 ± 247 ms (P < 0.001). Cl did not differentiate patients: 556 ± 108 vs 584 ± 117 ms (P = NS).Conclusions: Postextrasystolic changes in ST‐U segment configuration are dependent on bradycardia, low prematurity index of the PVC, and the lengthening of the postextrasystolic pause. U‐wave changes more frequently appeared in patients with malignant arrhythmias. Follow‐up study is needed to assess if they might be predictive for the occurrence or reoccurrence of arrhythmic episodes. A.N.E. 2002;7(1):17–21
Correction for Heart Rate Is Not Necessary for QT Dispersion in Individuals without Structural Heart Disease and Patients with Ventricular Tachycardia
Authors: Vassilikos Vassilios P. , Karagounis Labros A. , Psichogios Apostolos , Maounis Themistoclis , Iakovou John , Manolis Antonis S. , Cokkinos Dennis V. 
Published: October 2006

Background: It remains controversial whether QT dispersion should be corrected for heart rate, especially when the limitations of rate correction formulae are considered. We investigated whether incremental atrial pacing affects QT dispersion and the rate‐corrected values according to Bazett's formula in individuals without structural heart disease and in patients with history of sustained ventricular tachycardia.Methods: We studied 32 individuals without structural heart disease (group A), and 16 patients with a history of sustained ventricular tachycardia (group B). QT dispersion and corrected for heart rate QT dispersion using Bazett's formula (QTc dispersion) were calculated in sinus rhythm, and during continuous right atrial pacing for one minute at 100 and 120 beats/min.Results: Interobserver variability was not significant (P ≧ 0.10). QT dispersion did not differ at rest between groups A and B and did not change significantly from baseline at any heart rate in both groups. However, QTc dispersion increased significantly with atrial pacing in a similar manner in group A and group B (42 ± 19 ms at rest vs 53 ± 23 ms at 120 beats/min, P < 0.001 for group A, 39 ± 16 ms at rest vs 60 ± 19 ms at 120 beats/min, P < 0.001 for group B).Conclusions: We conclude that QT dispersion remains unchanged during atrial pacing at heart rates up to 120 beats/min in both individuals without structural heart disease and in patients with a history of sustained ventricular tachycardia. Correction by Bazett's formula results in prolongation of QTc dispersion, yielding values which may be misleading. A.N.E. 2002;7(1):47–52
Differentiation of Narrow QRS Complex Tachycardia Types Using the 12‐Lead Electrocardiogram
Authors: Erdinler Izzet , Okmen Ertan , Oguz Enis , Akyol Ahmet , Gurkan Kadir , Ulufer Tanju 
Published: October 2006

Background: Previous studies have shown that only 80% of narrow QRS supraventricular tachycardia (SVT) types can be differentiated by standard 12‐lead electrocardiographic (ECG) criteria. This study was designed to determine the value of some new ECG criteria in differentiating narrow QRS SVT.Methods and Results : 120 ECGs demonstrating paroxysmal narrow QRS complex tachycardia (QRS s 0.11 ms and rate > 120 beats/min) were analyzed. Forty atrioventricular reciprocating tachycardia (AVRT), 70 atrioventricular nodal reentrant tachycardia (AVNRT), and 10 atrial tachycardia defined with electrophysiologic study (EPS) consisted the study group. Eight surface ECG criteria were found to be significantly different between tachycardia types by univariate analysis. P waves separate from the QRS complex were observed more frequently in AVRT (70%) and atrial tachycardia (80%). Pseudo r’deflection in lead V1, pseudo S wave in inferior leads, and cycle length alternans were more common in AVNRT (55, 20, and 6%, respectively). QRS alternans was also present during AVRT (28%). ST‐segment depression (≧ 2 mm) or T‐wave inversion, or both, were present more often in AVRT (60%) than in AVNRT (27%). During sinus rhythm, manifest preexcitation was observed more often in patients with AVRT (42%). When a P wave was present, RP/PR interval ratio > 1 was more common in atrial tachycardia (90%). By multivariate analysis, presence of a P wave separate from the QRS complex, pseudo r’deflection in lead V1, QRS alternans, preexcitation during sinus rhythm, ST‐segment depression > 2 mm or T‐wave inversion, or both, were independent predictors of tachycardia type.Conclusions: Several new ECG criteria may be useful in differentiation of SVT types. Prediction of mechanism prior to EPS may provide additional benefits concerning the fluoroscopic exposure time and cardiac catheterization procedure. A.N.E. 2002;7(2):120–126
Computerized Vectorcardiography Telemetry: A New Device for Continuous Multilead ST‐Segment Monitoring of Ambulatory Patients. A Preliminary Report
Authors: Nørgaard Bjarne Linde , Sørensen Claus , Larsen Thomas , Thygesen Kristian , Dellborg Mikael 
Published: October 2006

Background: Continuous vectorcardiography ST‐segment monitoring has become a well‐established method in the surveillance of patients with acute myocardial ischemia. However, immobility of the vectorcardiography technique prevents monitoring of patients during ambulatory activities. Computerized vectorcardiography telemetry (CVT) with the capacity of real‐time ST‐segment analysis has been developed in an attempt to overcome this shortcoming. Recent data, however, indicate that changes in body position occasionally lead to pseudo‐ischemic ST‐segment changes during continuous ST‐segment monitoring.Aims: This report describes the technical features of the CVT system, presents clinical examples using CVT, and assesses the influence of changes in body position on ST‐vector magnitude (ST‐VM) during CVT, respectively.Methods: Clinical cases involving CVT are presented. The influence of changing body position during CVT monitoring was evaluated on 24 patients with suspected acute coronary syndromes, i.e., unstable angina or acute myocardial infarction. Each patient performed a specific body positional schedule.Results: We present three discrete clinical cases where CVT provided early and valuable evidence of ongoing myocardial ischemia. The consequences of different recumbent and ambulatory body positions on ST‐VM during CVT monitoring appear to be limited.Conclusion: Computerized vectorcardiography telemetry is a promising new tool for disclosing residual myocardial ischemic activity during the mobilization phase of patients with acute coronary syndromes. The clinical value of CVT needs further investigation in future trials. A.N.E. 2002;7(3):204–210