bluuebunny/crossref_metadata_2025 huggingface dataset:
Bias of QT Dispersion
Authors: Lund Kaspar , Arildsen Hanne , Perkiömäki Juha S. , Huikuri Heikki V. , May Ole , Pedersen Anders Kirstein
Published: October 2006

Background: Prolonged QT dispersion (QID) is associated with an increased risk of arrhythmic death but its accuracy varies substantially between otherwise similar studies. This study describes a new type of bias that can explain some of these differences.

Material: One dataset (DiaSet) consisted of 356 subjects: 169 with diabetes, 187 nondiabetic control persons. Another dataset (ArrSet) consisted of 110 subjects with remote myocardial infarction: 55 with no history of arrhythmia and 55 with a recent history of ventricular tachycardia or fibrillation.

Methods: 12‐lead surface ECGs were recorded with an amplification of 10 mm/mV at a paper speed of 50 mm/s. The QT interval was measured manually by the tangent‐method. The bias depends on the magnitude of the measurement errors and the measurable part of the bias increases with the number of the repeated measurements of QT.

Results: The measurable bias was significant for both datasets and decreased for increasing QTD in the DiaSet (P < 0.001) and in the ArrSet (P = 0.11). The bias was 2.5 ms and 1.9 ms at QTD = 38 ms and 68 ms, respectively, in the ArrSet, and 7.5 ms and 2.8 ms at QTD = 19 ms and 55 ms, respectively, in the DiaSet.

Conclusions: This study shows that random measurement errors of QT introduces a type of bias in QTD that decreases as the dispersion increases, thus reducing the separation between patients with low versus high dispersion. The bias can also explain some of the differences in the mean QTD between studies of healthy populations. Averaging QT over three successive beats reduces the bias efficiently. A.N.E. 2001;6(1):38–42
Effects of Glucose‐Insulin‐Potassium Infusion on QT Dispersion in Patients with Acute Myocardial Infarction
Authors: Wolk Robert , Lusawa Tomasz , Ceremuzynski Leszek
Published: October 2006

Background: Increased QT dispersion during acute myocardial infarction (AMI) has been associated with the occurrence of ventricular arrhythmias. Also, serum potassium levels have been shown to be relevant to the arrhythmic risk in this group of patients. The aim of the present study was to assess changes in QT dispersion during infusion of glucose‐insulin‐potassium (GIK) during AMI.

Methods: Patients from the Pol‐GIK study were analyzed retrospectively. The patients were selected from the placebo (1000 ml of 0.89% NaCI) and the GIK (1000 ml of 10% dextrose, 20–32 units of insulin, 80 mEq K+) groups (18 and 24 patients, respectively). QT interval duration and dispersion the difference between the longest and shortest QT intervals) were measured at baseline, 18–24 hours into placebo/GIK infusion and 24 hours after the end of infusion.

Results: In the placebo group, plasma potassium levels changed from 4.1 ± 0.5 mmol/L at baseline to 4.6 ± 0.8 mmol/L during infusion (P < 0.05) and 4.6 ± 0.4 mmol/L after infusion, whereas in the GIK group the respective values were 4.0 ± 0.4, 4.6 ± 0.3 (P < 0.0001), and 4.5 ± 0.5 mmol/L. QT interval duration was stable throughout the study and there was no difference between the groups. The two groups did not differ in respect to QT dispersion at any time point, the respective values were 79 ± 28, 65 ± 25, and 77 ± 27 ms in the placebo group, and 61 ± 35, 60 ± 26, and 76 ± 43 ms in the GIK group. The incidence of arrhythmias was also similar in both groups.

Conclusions: GIK, at the dose used, is unlikely to affect heterogeneity of ventricular repolarization during AMI. A.N.E. 2001;6(1)50–54
Modulation of Ventricular Repolarization and R‐R Interval Is Altered in Patients with Globally Impaired Cardiac 123I‐MIBG Uptake
Authors: Yoshida Naohiro , Nozawa Takashi , Igawa Akihiko , Fujii Nozomu , Kato Bun‐ichi , Mizumaki Koichi , Fujiki Akira , Asanoi Hidetsugu , Seto Hikaru , Inoue Hiroshi
Published: October 2006

Background: Cardiac 123l‐metaiodobenzylguanidine (MIBG) imaging is widely used to assess cardiac sympathetic neuronal function. However, physiologic significance of impaired cardiac MIBG uptake is not fully elucidated. The purpose of the present study was to determine influences of abnormal cardiac sympathetic neuronal function on heart rate variability (HRV) and ventricular repolarization process.

Methods: Twenty‐nine patients with prior myocardial infarction were divided into two groups by a heart‐to‐mediastinum ratio (H/M) of MIBG scintigraphy. Ten patients with globally decreased MIBG uptake (group I: H/M < 1.5), 19 patients with partially decreased MIBG uptake (group II: H/M < 1.5), and 17 control subjects with normal MIBG uptake (group III) were studied. Holler recording and a standard 12‐lead electrocardiography were used for evaluation of HRV, QT‐RR relation, and QT dispersion.

Results. Low, high, and total frequency components decreased in groups I and II, as compared to that of group III. The reduction of these frequency domain measures was more severe in group I than in group II, but the differences did not reach statistical significance. Circadian variation of frequency domain measures disappeared in group I. The slope of QT‐RR relation was significantly greater in group I than in groups II and III. QT dispersion was also greater in group I (64 ± 25 msec) than in group 11(43 ± 19 msec) and group III (28 ± 9 msec).

Conclusion. These results suggest that patients with sympathetic neuronal dysfunction inferred from globally impaired cardiac MIBG uptake have an altered modulation of ventricular repolarization process as well as decreased HRV.
Clinical, Electrocardiographic, and Biochemical Data for Immediate Risk Stratification in Acute Coronary Syndromes
Authors: Savonitto Stefano , Fusco Rossana , Granger Christopher B. , Cohen Mauricio G. , Thompson Trevor D. , Ardissino Diego , Califf Robert M.
Published: October 2006

The recent evolution in therapeutic options for acute coronary syndromes (ACS) mandates early risk stratification in order to select the appropriate treatment strategy for individual patients. Simple clinical data derived from the patient's medical history and physical examination, a standard twelve‐lead electrocardiogram (ECG), and determinations of biochemical markers of myocardial damage can be obtained in the emergency room and serve as a guide for deciding appropriate medical management and optimal use of available resources. Even the most important classification of the ACS is based upon a simple and dichotomous description of the ECG, where the presence of ST‐segment elevation mandates an immediate attempt to restore coronary perfusion (either pharmacologically or mechanically), whereas its absence suggests pharmacological stabilization before further evaluation. Across the whole spectrum of ACS, clinical history data (such as older age, previous coronary events, and diabetes) and clinical variables (such as higher heart rate, lower blood pressure, and higher Killip class) are the most powerful prognostic determinants at multivariate analyses derived from large databases. The ECG adds significant and independent prognostic information using the analysis of qualitative (direction of ST‐segment shift, associated T‐wave inversion, and presence of conduction disturbances) and quantitative (number of leads involved, amount of ST‐ segment shifts, duration of QRS) characteristics. Biochemical markers of myocardial damage have also been identified as independent predictors of events. In addition, retrospective analyses of clinical trials have suggested that biochemical markers might serve as a guide to select pharmacological therapy. However, how to best combine electrocardiographic and biochemical data for immediate risk stratification remains to be further elucidated. A.N.E. 2001;6(1):64–77
Perception and Documentation of Arrhythmias after Successful Radiofrequency Catheter Ablation of Accessory Pathways
Authors: Oddsson Hjörtur , Walfridsson Håkan , Edvardsson†† Nils
Published: October 2006

Background: Some patients continue to have palpitations in spite of successful ablation of Wolff‐Parkinson‐White (WPW) syndrome. Recurrence of accessory pathways as well as unrelated arrhythmias may explain the symptoms.

Methods: We followed 194 consecutive patients after successful radiofrequency catheter ablation of overt (147) or concealed (47) WPW syndrome. The mean duration of symptoms was 16 ±; 13 years. Atrial fibrillation was documented in 54 patients (24%) prior to ablation. 185 patients responded to a questionnaire 24 ±; 12 months after ablation.

Results: The physical well‐being was improved in 94%, unchanged in 5%, and deteriorated in 1%. However, 76 patients (39%) reported arrhythmia symptoms, in 40 patients causing pharmacological treatment (14 patients) and/or continued contact with their doctor. The underlying arrhythmias were orthodromic tachycardia (10), atrial fibrillation (12), premature beats (12), atrial flutter (1), and ventricular tachycardia (1), while in four patients no explanation was found. Minor symptoms in the other 36 patients were explained by premature beats in 29, while unexplained in 7. All patients with atrial fibrillation after ablation had atrial fibrillation before ablation. Ten relapses of WPW syndrome occurred: eight were known before the time of the questionnaire, two were confirmed at transesophageal atrial stimulation.

Conclusion: 94% patients with a long history of tachyarrhythmias due to the WPW syndrome reported improved physical well‐being after ablation, but palpitations were common during a 2‐year follow‐up period; 8% continued to use pharmacological antiarrhythmic treatment. Five percent had symptomatic relapses and in 6% atrial fibrillation episodes reoccurred, i.e., in half of those who had atrial fibrillation before ablation. A.N.E. 2001; 6(3):216–221
Value and Limitations of Ambulatory ECG Monitoring for Assessment of Myocardial Ischemia
Authors: Tzivoni Dan
Published: October 2006

Ambulatory ECG monitoring (AEM) is the only available method to assess the presence and severity of myocardial ischemia during daily life. Several investigators have shown that the recording systems currently used can detect ischemic changes with similar accuracy as treadmill exercise testing. Ischemic changes on AEM are, however, present in only 40%‐60% of patients with coronary artery disease (CAD) and positive exercise tests. For this reason, and because of the high day‐to‐day variability in daily ischemic changes, AEM cannot be used as a screening tool for detecting CAD or for evaluating severity of ischemia in individual patients. In patients with proven CAD, ischemic changes on AEM are associated with an adverse outcome in patients with stable and unstable ischemic syndromes, and in postmyocardial infarction patients. Suppression of daily ischemia seems to be associated with improved outcome. The mechanism of daily ischemia is not identical to exercise‐induced ischemia. In addition to increased demand, which is a major contributor to AEM detected‐ischemia, increased coronary tone also seems to play a major role. AEM has been shown to be a useful and reliable tool to assess the efficacy of various antiischemic drugs. A.N.E. 2001; 6(3):236–242
THE ORDER OF VENTRICULAR EXCITATION IN HUMAN BUNDLE‐BRANCH BLOCK*†
Authors: Wilson Frank N. , Macleod A. Garrard , Barker Paul S.
Published: October 2006

IN previous articles from this laboratory1,2 it has been pointed out that, in accordance with the laws which govern the flow of electric currents in volume conductors, the potential variations produced by the cardiac muscle are very much greater in magnitude in the immediate neighborhood of the heart than at a distance from it. It has been shown that when one electrode of the string galvanometer is placed upon the pre‐cordium, the position of the second electrode, so long as it is distant from the heart, has comparatively little influence upon the form of the ventricular electrocardiogram. Attention has been called to certain resemblances between leads of this type and direct leads of the kind employed by Lewis and Rothschild3 in which one electrode is placed in actual contact with the ventricular muscle and the other upon the chest wall. In both cases the form of the ventricular complex is determined in a very large measure, although not to quite the same extent in the former as in the latter, by the potential variations of the exploring electrode; in both cases the muscle units which lie nearest this electrode exert individually a much greater effect upon its potential than those which are more distant from it.

Curves obtained by leading from points on or near the heart to one of the extremities utilized in taking the three standard indirect leads may be freed from the influence exerted by potential variations of the indifferent electrode by a method which we have recently described.4 When this electrode is placed upon the left leg the correction is made by subtracting from each ordinate of the recorded curve one‐third of the sum of the deflections, measured in. millivolts, inscribed in Leads II and III at the corresponding instant in the cardiac cycle. It is possible in this way to determine, at least approximately, the time course of the potential of the exploring electrode, and thus to eliminate any difference beween direct and semidirect leads for which potential variations of the indifferent electrode are responsible.
Effects of Hormone Replacement Therapy on Heart Rate Variability in Postmenopausal Women
Authors: Yildirir Aylin , Kabakci Giray , Yarali Hakan , Aybar Funds , Akgul Ebru , Bukulmez Orhan , Tokgozoglu Lale , Gurgan Timur , Oto Ali
Published: October 2006

Background: Hormone replacement therapy (HRT) is associated with reduced cardiovascular risk, but the underlying mechanism(s) are not fully understood. This study investigated the effects of a 6‐month course of HRT on cardiac autonomic function parameters assessed by heart rate variability (HRV) in postmenopausal women.

Methods: Forty‐six healthy postmenopausal women (age 48 ± 5, range 40–60) with normal baseline electrocardiogram and negative exercise testing were enrolled. HRT, which was either 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate or 0.625 mg/day CEE alone were administered depending on hysterectomy status. Power spectral analysis of HRV was performed to calculate the low frequency component in absolute (LF) and normalized units (LF nu), high frequency component in absolute (HF), and normalized units (HF nu), and the LF/HF ratio. The standard deviation of RR intervals (SDNN) was calculated from the time series of RR intervals.

Results: A 6‐month course of HRT did not significantly alter resting heart rate (P > 0.05). The LF/HF ratio and LF nu significantly decreased after HRT (P = 0.022 and P = 0.032), whereas a significant increase was noted in the HF component of HRV (P = 0.043), indicating an improvement in cardiac autonomic function. The SDNN value, which was 28.8 ± 11.8 ms before HRT significantly increased to 35.4 ± 16.7 ms after 6 months (P = 0.011).

Conclusion: Our results indicate that a 6‐month course of HRT may significantly improve cardiac autonomic function parameters, a finding that could at least partly explain the potential cardiopro‐tective effect(s) of HRT. A.N.E. 2001;6(4):280–284
Age, Gender, and Autonomic Tone Effects on Surface Electrocardiographic Indices of Ventricular Repolarization
Authors: Taneja Taresh , Larsen Jennifer , Goldberger Jeffrey , Kadish Alan
Published: October 2006

Background: Prolonged QT offset dispersion (QToD), an index of heterogeneity of ventricular repolarization, is thought to be an independent predictor of all‐cause and cardiovascular mortality. However the influence of gender and autonomic tone in healthy adults on age‐related changes in measures of ventricular repolarization are not well characterized.

Methods: QToD and T wave complexity were measured in 56 healthy subjects with no detectable heart disease (by echo and stress test)—38 young subjects with a mean age of 28 ± 4 years and 18 old subjects with a mean age of 71 ± 7 years. QToD and T wave complexity were computed from 12‐lead ECGs using the GE Marquette QT Guard automated analysis program with manual over‐reading at rest (baseline), following exercise, and double autonomic blockade with atropine and propranolol. Data was analyzed using factorial ANOVA.

Results: Young males had a significantly greater QToD than young and old females at baseline (28 ± 5 ms, 23 ± 5 ms, and 22 ± 5 ms, respectively, P < 0.01), an intrinsic effect independent of changes in autonomic tone. In contrast, females had significantly greater T wave complexity than males following exercise and double autonomic blockade with a definite trend at baseline. There was no correlation between T wave complexity and QToD.

Conclusions: Age and gender demonstrate a complex interaction on indices of myocardial repolarization with different measures behaving differently. These findings have implications for better understanding age and gender effects on myocardial electrophysiology. A.N.E. 2001;6(4):290–297
Heart Rate Variability in Patients with Congenital Long QT Syndrome
Authors: Perkiömäki Juha S. , Zareba Wojciech , Couderc Jean‐Philippe , Moss Arthur J.
Published: October 2006

Background: The congenital long QT syndrome (LQTS) affecting myocardial repolarization is caused by mutations in different cardiac potassium or sodium channel genes. Adrenergic triggers are known to initiate life‐threatening torsade de pointes ventricular tachycardias in LQTS patients, and anti‐adrenergic therapy has been shown to be effective in many cases. Despite this well‐documented adrenergic component, the data about autonomic modulation of the heart rate in LQTS, as described by heart rate variability (HRV) analysis, are very limited.

Methods: Conventional time‐ and frequency‐domain and newer nonlinear measures of HRV were compared in resting conditions among 27 LQTS patients with gene mutations at the LQT1 (n = 8), LQT2 (n = 10) or LQT3 (n = 9) loci and 34 LQTS noncarrier family members.

Results: None of the conventional time‐ or frequency‐domain or newer nonlinear measures of HRV differed significantly between the LQTS carriers and LQTS noncarriers or between the LQT1, LQT2, and LQT3 carriers.

Conclusions: These findings suggest that baseline cardiac autonomic modulation of the heart rate measured in resting conditions by traditional or newer nonlinear measures of HRV is not altered in LQTS patients. Furthermore, no differences are observed in HRV parameters between LQTS patients with potassium (KvLQT1, HERG), and sodium (SCN5A) ion channel gene mutations. HRV analysis in resting conditions does not improve phenotypic characterization of LQTS patients. A.N.E. 2001;6(4):298–304
Variable Expression of Long QT Syndrome Among Gene Carriers from Families with Five Different HERG Mutations
Authors: Benhorin Jesaia , Moss Arthur J. , Bak Matthew , Zareba Wojciech , Kaufman Elizabeth S. , Kerem Batsheva , Towbin Jeffrey A. , Priori Silvia , Kass Robert S. , Attali Bernard , Brown Arthur M. , Ficker Eckhard
Published: October 2006

Objectives: This study assessed the phenotypic variability of LQTS in carriers with the same and with different mutations in the LQT2 gene.

Background: Mutations of ion‐channel genes are known to cause the long QT syndrome (LQTS), a disorder associated with distinctive genotypic‐specific electrocardiographic patterns and variable clinical expression.

Methods: Clinical and electrocardiographic characteristics were assessed in five large LQTS families, each with a different mutation of the HERG gene (LQT2; n = 469, 69% genotyped, 102 carriers). One mutation was located on the N‐terminus and the other four on the C‐terminus of the HERG channel protein.

Results: The QTc duration and the frequency of cardiac events (syncope and LQTS‐related cardiac arrest/deatht were similar among carriers with the five HERG mutations. QTc was as variable in carriers of the same mutation as it was among carriers with different HERG mutations (P = 0.19). Qualitative assessment of the electrocardiograms revealed extensive intra‐and interfamilial variability in T‐vvave morphology. Among carriers with multiple electrocardiograms extending over 2 to 7 years, variation in QTc over time was minimal. A strong association was found between QTc and the occurrence of cardiac events in carriers of all five mutations.

Conclusions: The clinical expression of LQTS was equally variable in carriers from families with the same or different HERG mutations. These findings highlight the complexity of the clinical phenotype in this Mendelian dominant disorder and suggest that one or more modifier genes contribute to the variable expression of this syndrome. A.N.E. 2002;7(1):40–46
Patients with Persistent Atrial Fibrillation Taking Oral Verapamil Exhibit a Lower Atrial Frequency on the ECG
Authors: Bollmann Andreas , Sonne Kai , Esperer Hans‐Dieter , Toepffer Ines , Klein Helmut U.
Published: October 2006

Background: While there is agreement that verapamil attenuates the AF‐ induced refractory period shortening when given before AF induction, controversy exists regarding its effects when given after the onset of persistent AF. This study aimed to compare atrial fibrillatory frequency obtained from the surface ECG in patients with persistent atrial fibrillation (AF) with oral verapamil treatment to those without this treatment.

Methods and Results: Surface ECG recordings were performed in 57 patients (34 male, 23 female, mean age 59 ± 11 years) with persistent AF (> 7 days). The frequency content of the fibrillatory baseline was quantified using digital signal processing (filtering, QRST complex averaging and subtraction. Fourier transformation). In 27 patients with verapamil treatment (120 or 240 mg/day for at least 7 days) mean fibrillatory frequency measured 6.4 ± 0.2 Hz, compared to 7.0 ± 0.4 Hz (P = 0.012) in 30 patients without verapamil. In a subset of 20 randomly selected patients (10 with, 10 without verapamil treatment) a 24‐hour Holter ECG recording was performed and fibrillatory frequency determined at 4 PM, 10 PM, 4 AM, and 10 AM. While there was a significant frequency reduction in the verapamil treated patients at night (P = 0.011), it remained constant over time in the other patients.

Conclusion: In patients with persistent AF, fibrillatory frequency assessed by spectral analysis of the surface ECG is lower in patients taking verapamil. A.N.E. 2002;7(2):92–97
Observer Variability and Optimal Criteria of Transient Ischemia During ST Monitoring with Continuous 12‐lead ECG
Authors: Jernberg Tomas , Cronblad Jörgen , Lindahl Bertil , Wallentin Lars
Published: October 2006

Background: ST monitoring with continuous 12‐lead ECG is a well‐established method in patients with unstable coronary artery disease (CAD). However, the method lacks documentation on optimal criteria for episodes of transient ischemia and on observer variability.

Methods: Observer variability was evaluated in 24‐hour recordings from 100 patients with unstable CAD with monitoring in the coronary care unit. Influence on ST changes by variations in body position were evaluated by monitoring 50 patients in different body positions. Different criteria of transient ischemia and their predictive importance were evaluated in 630 patients with unstable CAD who underwent 12 hours of monitoring and thereafter were followed for 1 to 13 months. Two sets of criteria were tested: (1) ST deviation ≧ 0.1 mV for at least 1 minute, and (2) ST depression ≧ 0.05 mV or elevation ≧ 0.1 mV for at least 1 minute.

Results: When the first set of criteria were used, the interobserver agreement was good (kappa = 0.72) and 8 (16%) had significant ST changes in at least one body position. Out of 100 patients with symptoms suggestive of unstable CAD and such ischemia, 24 (24%) had a cardiac event during follow‐up. When the second set of criteria were used, the interobserver agreement was poor (kappa = 0.32) and 21(42%) had significant ST changes in at least one body position. Patients fulfilling the second but not the first set of criteria did not have a higher risk of cardiac event than those without transient ischemia (5.3 vs 4.3%).

Conclusions: During 12‐lead ECG monitoring, transient ischemic episodes should be defined as ST deviations ≧ 0.1 mV for at least 1 minute, based on a low observer variability, minor problems with postural ST changes and an important predictive value. A.N.E. 2002;7(3):181–190
The Value of P Dispersion on Predicting Atrial Fibrillation After Coronary Artery Bypass Surgery: Effect of Magnesium on P Dispersion
Authors: Dagdelen Sinan , Toraman Fevzi , Karabulut Hasan , Alhan Cem
Published: October 2006

Background: AF is a frequent arrhythmia complicating CABG, and it is well known that dispersion and prolongation of P wave increases the risk of AF. The aim of this study was to investigate the effect of magnesium (Mg) treatment on P‐wave duration and dispersion in patients undergoing CABG.

Method: The study included 148 consecutive patients (33 women, 115 men; mean age 62.1 ± 7.0 years) undergoing CABG who were randomly allocated to two groups. Group A consisted of 93 patients to whom 1.5 g daily MgSO4 infusion was applied the day before surgery, just after operation, and 4 days following surgery, and group B consisted of 55 control patients. From the preoperative and postoperative fourth day, 12‐lead ECG recordings, duration of the P waves, and P‐wave dispersions were calculated.

Results: There were no differences between the two groups with regard to age, sex, and blood Mg level. Comparison of the baseline and day 4 ECG measurements showed no difference as far as heart rates, duration of PQ, and QRS intervals were concerned. AF developed in 2 (2%) cases in group A and in 20 (36%) cases in group B (P < 0.001). There was no difference between the two groups when average basal P max, P min, P dispersion, and day 4 P min values were compared. In group A, fourth day P max (94.3 ± 11.8 vs 101.0 ± 13.2 ms; P = 0.0025) and P dispersion (38.2 ± 9.2 vs 44.9 ± 10.9 ms; P = 0.0002) were significantly lower as compared to group B. Comparing the patients who developed AF, and who did not, no difference was detected with regard to baseline P max, P min, P dispersion, and day 4 P min. Day 4 P max (95.1 ± 11.8 vs 106.4 ± 14.0 ms, P = 0.0015) and P dispersion (38.9 ± 8.8 vs 50.7 ± 13.0 ms, P = 0.001) of patients who developed AF were significantly higher. Baseline Mg levels were similar in patients who developed AF, and who did not, but the day 4 Mg level was significantly lower in AF group (2.0 ± 0.23 vs 2.15 ± 0.26 mg/dL, P < 0.001).

Conclusion: Perioperative Mg treatment reduces P dispersion and the risk of developing AF in patients undergoing CABG. A.N.E. 2002;7(3):211–218
Directct Epicardial Mapping Can Differentiate Hibernating from Scarred Myocardium: A Validation Study with 18F‐FDG‐PET
Authors: Vahlhaus Christian , Schäfers Michael , Bruns Hans‐Jürgen , Janssen Frauke , Stypmann Jorg , Hammel Dieter , Scheld Hans H. , Schober Otmar , Breithardt Günter , Wichter Thomas
Published: October 2006

Aim: This study investigated the value of epicardial mapping immediately before CABG in the differentiation of hibernating from scarred myocardium in correlation to the noninvasive gold standard 18F‐FDG PET.

Methods and Results: In 35 patients with CAD, myocardial perfusion (99mTc‐Tetrofosmin‐SPECT), viability (18F‐FDG‐PET), and function (LVangiography) were assessed before CABG. 102 bipolar epicardial electrograms per patient (n = 3570 electrograms) were recorded simultaneously with a ventricular jacket array. Based on the scintigraphic and LV angiographic data at the site of each electrode with good myocardial contact (n = 1963), segments (n = 492, 14.1 ± 5.6 per patient; mean ± SD) were classified into three groups: hibernating (n = 139), scarred (n = 104), and control (n = 249). Regional mean bipolar voltage values were calculated for Receiver Operating Characteristic (ROC) analysis. Mean bipolar voltage was significantly lower in scarred when compared to hibernating myocardium. ROC curve analysis (area under the curve of O.92 ± 0.47, mean ± SE) for mean bipolar voltage to discriminate between hibernating and scarred myocardium revealed a sensitivity of 94% with a specificity of 83% at a cut‐off value of 8.75 mV.

Conclusion: Hibernating myocardium can be differentiated correctly from scarred myocardium by direct epicardial mapping. In the future, hibernating myocardium may be detectable by body surface mapping techniques using inverse solutions. A.N.E. 2002;7(4):349–356
The Immediate and Short‐Term Effect of Successful Percutaneous Coronary Intervention on Repolarization in Acute Myocardial Infarction Patients
Authors: Giedrimiene Dalia , Giri Satyendra , White C. Michael , Giedrirnas Evaldas , Kluger Jeffrey
Published: October 2006

Objectives: The primary objective was to assess the immediate and short‐term impact of successful percutaneous coronary intervention (PCI) on QT dispersion (QT disp) and corrected QT dispersion (QTc disp). Secondarily, the impact of PCI on QT and QTc disp within different infarct‐related arteries and the impact of successful PCI in these different arteries were evaluated.

Methods: Patients (n = 140, age 61.6 ± 12.9, 69% male) undergoing direct primary PCI for acute Ml were evaluated. Twelve‐lead ECGs were obtained before baseline), immediately after (0 h), 24hours after, and 3 days after PCI. The QT and QTc interval in each of the 12‐leads were measured and the shortest interval was subtracted from the longest to derive the QT disp and QTc disp, respectively.

Results: Angiography showed blockages in the left anterior descending, right coronary artery, and circumflex in 37.1, 48.9, and 15.0% of patients, respectively. Overall, 97 patients achieved successful reflow. QT and QTc disp were significantly improved in the group with successful reflow at each follow‐up time after PCI versus baseline and corresponding values in the unsuccessful reflow group. QT disp was improved among patients with successful reflow irrespective of which infarct artery was responsible for the acute myocardial infarction.

Conclusions: Successful reflow with PCI is associated with a rapid reduction in QT disp and QTc disp that is maintained for at least 3 days after the event. Conversely, unsuccessful reflow was not associated with significant reductions in QT or QTc disp. A.N.E. 2002;7(4):357–362
P Wave Dispersion and P Wave Duration on SAECG in Predicting Atrial Fibrillation in Patients with Acute Myocardial Infarction
Authors: Rosiak Marcin , Bolinska Halina , Ruta Jan
Published: October 2006

Background: Atrial fibrillation (AF) is a frequent complication of acute myocardial infarction (AMI), with reported incidence of 7% to 18%. The incidence of congestive heart failure, in‐hospital mortality, and long‐term mortality is higher in AMI patients with AF than in AMI patients without AF. P wave duration on signal‐averaged ECG (PWD) and P wave dispersion on standard ECG (Pd) are noninvasive markers of intra‐atrial conduction disturbances, which are believed to be the main electrophysiological cause of AF.

Methods: In the present study we investigated prospectively whether P wave duration on SAECG and P wave dispersion on standard ECG can predict development of AF in a group of patients with AMI. One hundred and thirty patients (100 men and 30 women, aged 56.9 ± 12) with AMI were investigated. PWD, Pd, their clinical and hemodynamic characteristics were collected.

Results: During the observation up to 14 days, 22 patients (16.9%) developed AF. Univariate analysis variables associated with development of AF: age > 65 years, Killip class III‐IV, PWD > 125 ms, and Pd > 25 ms. Stepwise logistic regression analysis showed that age > 65 years, PWD > 125 ms, and Pd > 25 ms were independently associated with AF.

Conclusions: PWD and Pd both measured in a very early period of AMI are useful in predicting AF. A.N.E. 2002;7(4):363–368
Predictive Value of Admission Electrocardiogram For Multivessel Disease in Acute Anterior and Anterior‐Inferior Myocardial Infarction
Authors: Kürüm Turhan , Öztekin Erkan , Özçelik Fatih , Eker Hüseyin , Türe Mevlüt , Özbay Gültç
Published: October 2006

Background: Our aim was to investigate the correlation between admission ECG and coronary angiography findings in terms of predicting the culprit vessel responsible for the infarct or multivessel disease in acute anterior or anterior‐inferior myocardial infarction (AMI).

Methods: We investigated 101 patients with a diagnosis of anterior AMI with or without ST‐segment elevation or ST‐segment depression in at least two leads in Dll, III, aVF. The patients were classified as those with vessel involvement in the left anterior descending (LAD) coronary artery and patients with multivessel disease. Vessel involvement in LAD + circumflex artery (Cx) or LAD + right coronary artery (RCA) or LAD + Cx + RCA were considered as multivessel disease. Thus, (a) anterior AMI patients with reciprocal changes in inferior leads, (b) anterior AMI patients with inferior elevations, (c) all anterior AMI patients according to the ST‐segment changes in the inferior region were analyzed according to the presence of LAD or multivesssel involvement.

Results: Presence of ST‐segment depression in aVL and V6 was significantly correlated with the presence of multivessel disease in anterior AMI patients with reciprocal changes in the inferior leads (P = 0.005 and P = 0.003, respectively). No statistically significant difference between the leads were detected in terms of ST‐segment elevation in predicting vessel involvement in the two groups of anterior AMI patients with inferior elevations. When all the patients with anterior AMI were analyzed, the presence of ST‐segment depression in leads aVL, V4, V5 and V6 were significantly associated with the presence of multivessel disease (P = 0.035, P = 0.010, P = 0.011, P = 0.001, respectively).

Conclusions: The presence of ST‐segment depression in anterolateral leads in the admission ECG of anterior AMI patients with reciprocal changes in inferior leads was associated with multivessel disease.
Heart Rate Variability by Triangular Index in Infants Exposed Prenatally to Cocaine
Authors: Ken Mehta Sudhir , Super Dennis M. , Salvator Ann , Fradley Linda Goetz , Connuck David , Kaufman Elizabeth S.
Published: October 2006

Background: In adults, heart rate variability triangular index (HRVi) is a highly reproducible measure of heart rate variability (HRV), which makes it more suitable for use in longitudinal studies. Although normative data have been published for newborns, studies in infants with pathological conditions are lacking.

Methods: From 1997 to 2000, within the first 4 days of life, we prospectively evaluated HRVi in cocaine‐exposed asymptomatic newborns (N = 97) by Holter monitoring. Their data were compared with infants from two control groups (one with no in utero drug exposure, N = 102; the other with exposure to alcohol, nicotine, or marijuana but no cocaine, N = 111).

Results: In assessing concordance between and within operators for HRVi, the intraclass correlations were 0.983 (95% Cl: 0.958, 0.994) and 0.997 (95% Cl: 0.984, 0.999), respectively. Infants with in utero cocaine exposure had significantly (P < 0.0001) lower HRVi than those exposed to other drugs and to no drugs in utero. If abnormal HRVi is defined as < fifth percentile for the no drug exposed group (HRVi < 8), 10% of the cocaine‐exposed newborns, in contrast to 2% in each of the control groups (P = 0.003) had abnormal values.

Conclusion: HRVi is a reliable measure to study heart rate variability in newborns. Asymptomatic infants with in utero cocaine exposure have lower HRVi. Our study supports the clinical use of an abnormal HRVi as a value < 8 for newborn infants. A.N.E. 2002;7(4):374–378
Cardiac Effects of Chronic Oral Beta‐Blockade:
Authors: Extramiana Fabrice , Maison‐Blanche Pierre , Tavernier René , Jordaens Luc , Leenhardt Antoine , Coumel Philippe
Published: October 2006

Background: Although well established on the sinus node, the effects of beta‐blockade on ventricular repolarization are still conflicting. The aim of the study was to investigate the effects of a chronic beta‐blockade on sinus node and repolarization parameters and their relationship.

Methods: Sixteen healthy volunteers (10 males, mean age: 40 ± 6.7 years) were randomized to placebo or atenolol (100 mg). After 7 days, subjects were crossed over. Heart rate (HR) and HRV indices were calculated from long‐term ECG recordings separately during the day and at night, together with ventricular repolarization parameters (QT interval duration and QT rate‐dependence).

Results: Mean R‐R intervals were significantly and consistently increased after atenolol (Day: 916 ± 103 ms vs. 712 ± 89 ms, and Night: 1149 ± 93 vs. 996 ± 125 ms). HRV changes under atenolol were also consistent, with a significant decrease in sympathovagal ratio. In contrast, atenolol only lowered diurnal QT rate‐dependence (0.123 ± 0.032 vs. 0.190 ± 0.065 on placebo, P < 0.001), but not the nocturnal pattern. After multivariate analysis QT rate‐dependence changes induced by atenolol were correlated with pretreatment QT/RR relation (r = 0.65, P < 0.01) but not with any HR or HRV parameters.

Conclusions: In healthy subjects, repolarization changes following chronic beta‐blockade cannot be predicted by HR or HRV changes, but are dependent on pretreatment rate‐dependence. A.N.E. 2002;7(4):379–388
Late QRS Activity in Signal‐Averaged Magnetocardiography, Body Surface Potential Mapping, and Orthogonal ECG in Postinfarction Ventricular Tachycardia Patients
Authors: Korhonen Petri , Tierala Ilkka , Simelius Kim , Väänänen Heikki , Mäkijärvi Markku , Nenonen Jukka , Katila Toivo , Toivonen Lauri
Published: October 2006

Background: Delayed electrical activity necessary for re‐entrant ventricular tachycardia (VT) is detectable noninvasively with high resolution techniques. We compared high resolution signalaveraged analysis of magnetocardiography (MCG), body surface potential mapping (BSPM), and orthogonal three‐lead ECG (SA‐ECG) in the identification of patients prone to VT after myocardial infarction (Ml).

Methods: Patients with remote myocardial infarction and cardiac dysfunction were studied, 22 with (VT group) and 22 without VT (control group). MCG with seven channels and BSPM with 63 and SA‐ECG with three orthogonal leads were registered. After signal‐averaging and highpass filtering, three time domain analysis (TDA) parameters describing late electrical activity were computed: QRS duration (QRSd), root mean square amplitude (RMS) of the last 40 ms of QRS, and the duration of the low‐amplitude QRS end (LAS).

Results: All parameters by each method were significantly different between the patients’groups. For example, LAS parameter in MCG was 59 (SD 22) ms in the VT group vs. 37 (SD 13) ms in controls (P < 0.001), 77 (SD 22) ms vs. 56 (SD 19) ms in BSPM (P = 0.002), and 60 (SD 24) ms vs. 39 (SD 22) ms in SA‐ECG (P = 0.005). The combination of LAS parameter in MCG and SA‐ECG resulted in improved performance in comparison to any single parameter with 95% sensitivity and 68% specificity.

Conclusions: All three high resolution methods identified VT propensity among post‐Mi patients with cardiac dysfunction and between‐method differences were small. Information in MCG and SA‐ECG may be complementary and their combination could be of value in postinfarction arrhythmia risk assessment. A.N.E. 2002;7(4):389–398
Implementation of MADIT and MUSTT in Clinical Practice: Results of an International Survey
Authors: Nisam Seah , Henry Sophie , Wilber David J.
Published: October 2006

Background: The long‐awaited dramatically positive outcome of the Multicenter Automatic Defi‐brillator Implantation Trial (MADIT II), just published by Moss et al.,14 has generated cardiologists’interest on the implementation into clinical practice of that trial. Important lessons may be learned by examining the clinical implementation of two preceding randomized, prospective, prophylactic ICD trials: the original MADIT trial, published late 1996, and the Multicenter Unsustained Tachycardia Trial (MUSTT), published late 1999. Both demonstrated that implantable cardioverter defi‐brillators reduce all‐cause mortality by over 50% in high risk patients without previous sustained arrhythmias.

Methods: In early 2000, we surveyed 133 active electrophysiology centers (47 American, 81 European, 5 Canadian) to determine the extent to which these practices have been implemented in clinical practice during 1999, and the responses were compared to a similar survey for the year 1998.

Results: ICDs implanted for MADIT or MUSTT criteria accounted for 18% of new ICD implants in 1999, 65% greater than in 1998, increasing from 6% to 11% in Europe, and from 15% to 24% in America. During 1999, 53% of patients receiving ICDs for these indications were inpatients identified during hospitalization, 27% were outpatients referred specifically for MADIT/MUSTT indications, and 20% were identified by routine screening. Per the survey, in 1999 68% of responders were “somewhat 10–20%)” and 14% were “considerably (>20%)” more likely to implant ICDs for all indications.

Conclusions: Extrapolating the results of this survey to all initial ICD implants for 1999, we estimate that 8500 implants for MADIT/MUSTT criteria took place in 1999, with the overall number of such implants substantially increased over the previous year, irrespective of geographic location, and influenced significantly by the publication of MUSTT. However, screening and implant practices between centers continue to vary over a broad spectrum. It will be interesting to observe whether similar patterns will follow with MADIT II. A.N.E. 2002;7(4):399–405
Spark Plasma Sintering of High‐Density Antimony‐Doped Tin Oxide Ceramics from Nanoparticles
Authors: Zhang Jianrong , Gao Lian , Chen Minghai
Published: October 2006

The spark plasma sintering (SPS) technique was used for the first time to fabricate antimony‐doped tin oxide (ATO) ceramics from monodispersed ATO nanoparticles synthesized by the hydrothermal method. The ceramics' relative density increased from 83.7% when sintered at 750°C to the highest value of 97.4% at 850°C, and a corresponding highest conductivity of 2.2 × 10−4Ω·cm was also obtained at this temperature.
Enhanced Ability of Nanostructured Titania Film to Assist Photodegradation of Rhodamine B in Water Through Natural Aging
Authors: Wu Jin‐Ming , Huang Bing
Published: October 2006

Gradually but significantly improved abilities of titania films with various nanofeatures and crystal structures to assist photodegradation of trace rhodamine B in water were observed when the films were subjected to natural aging. The so‐called natural aging behavior can be attributed to the gradual increase in the surface hydroxyl groups that are beneficial to the photocatalytic reaction.
Peculiar Dielectric Behaviors of (Na1/2Bi1/2)0.87Pb0.13TiO3 Thin Films
Authors: Zhou Z. H. , Wang J.
Published: October 2006

PbTiO3‐doped sodium bismuth titanate (Na1/2Bi1/2)1−xPbxTiO3 of perovskite structure is one of the best‐known piezoelectrics/ferroelectrics. However, it has not been properly investigated in any thin‐film forms. In this study, the dielectric properties of (Na1/2Bi1/2)0.87Pb0.13TiO3 thin films synthesized via a sol–gel route were investigated. They exhibit a strong frequency dispersion of the dielectric permittivity at relatively high frequencies, which is shifted to lower frequencies with increasing temperature. The electrical behavior can be fitted using Jonscher's universal law for dielectric relaxation. The peculiar dielectric behaviors observed can be ascribed to the coexistence of two different dielectric phases in the films, which is believed to be associated with the growth of the local Pb2+TiO3 nanoclusters upon substitution of Pb2+ for Na+/Bi3+ in the (Na1/2Bi1/2)1−xPbxTiO3 films.
An asymmetric ion channel derived from gramicidin A
Authors: Xie Xiulan , Al‐Momani Lo'ay , Reiß Philipp , Griesinger Christian , Koert Ulrich
Published: October 2006

The biological ion channel gramicidin A (gA) was modified by synthetic means to obtain the tail‐to‐tail linked asymmetric gA‐derived dimer compound 3. Single‐channel current measurements for 3 in planar lipid bilayers exhibit an Eisenman I ion selectivity for alkali cations. The structural asymmetry does not lead to an observable functional asymmetry. The structure of 3 in solution without and with Cs cations was investigated by 1H‐NMR spectroscopy. In CDCl3/CD3OH (1 : 1, v/v), 3 forms a mixture of double‐stranded β‐helices. Upon addition of excess CsCl, the double‐stranded species are converted completely into one new conformer: the right‐handed single‐stranded β‐helix. A combination of DQF‐COSY and TOCSY was used for the assignment of the 1H‐NMR spectrum of the Cs–3 complex in CDCl3/CD3OH (1 : 1, v/v). A total of 69 backbone, 27 long‐range, and 64 side‐chain distance restraints were obtained from NOESY together with 25 φ and 14 χ1 torsion angles obtained from coupling constants. These data were used as input for structure calculation with dyana built in sybyl 6.8. A final set of 11 structures with an average rmsd for the backbone of 0.45 Å was obtained (PDB: 1TKQ). The structure of the Cs–3 complex in solution is equivalent to the bioactive channel conformation in the membrane environment.
Insulin sensitivity in streptozotocin‐induced diabetic rats treated with different doses of 17β‐oestradiol or progesterone
Authors: Ordóñez Patricia , Moreno María , Alonso Ana , Fernández Rebeca , Díaz Fernando , González Celestino
Published: October 2006

It has been reported that in streptozotocin (STZ)‐induced diabetes, hyperglycaemia leads to progressive insulin resistance of the peripheral tissues. In this study, we tried to elucidate the effects of hyperglycaemia on insulin sensitivity and insulin signalling in ovariectomized (STZ)‐induced diabetic rats. In addition, we attempted to demonstrate the role of 17β‐oestradiol and progesterone on insulin sensitivity, focusing on their effects on key proteins of skeletal muscle, insulin receptor (IR) and glucose transporter‐4 (Glut‐4). Our results show that hyperglycaemia could modulate insulin signalling, at the IR and Glut‐4 level, in different ways depending on exposure time. 17β‐Oestradiol and progesterone have different effects on insulin signalling. 17β‐Oestradiol treatment improves insulin sensitivity, but its action is dependent on the exposure time and its plasma level. During the early period of treatment (days 6–11), this hormone counteracts the effects of hyperglycaemia downstream of the IR, whereas during the later period of treatment (days 11–16), it may counteract the effects of hyperglycaemia by modulating IR relative tyrosine phosphorylation. By contrast, progesterone only improves insulin sensitivity during the early period of treatment (days 6–11), and this effect is not associated with changes in IR and Glut‐4 content. Both hormones have a protective role in skeletal muscle against the effects of glucose toxicity, but their effects begin at different stages of treatment. These new findings improve our understanding of insulin resistance in type 1 diabetes mellitus and of the risk/benefit ratio when 17β‐oestradiol and progesterone are used in oral contraceptives or hormone replacement therapy taken by menopausal women with controlled type 1 diabetes mellitus.