ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00288.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Background:It has been hypothesized that an interaction between sympathetic nervous activity and an abnormal myocardium plays a role in the development and progression of hypertrophic cardiomyopathy (HCM).Methods:In the present study we investigated cardiac autonomic function by 24‐hour spectral analysis of heart rate variability (HRV) in 18 patients with HCM, without evidence of heart failure, and 18 controls of similar age.Results:We found a significant reduction of 24 hour variance in HCM patients relative to controls (15,000 ± 9480 ms2vs 24,720 ± 12,450 ms2respectively; p<0.05). Moreover, a loss of the expected day‐night changes in the low frequency (LF) spectral component (expressed in normalized units), and LF/HF ratio (HF; high frequency component) were observed in HCM patients. Decreased day‐night changes in LF/HF ratio were previously reported in patients with mild hypertension, uncomplicated coronary disease, and after myocardial infarction, conditions in which it seems to exist a higher than normal sympathetic activity. No significant correlations were found between HRV indices and echocardiographic standard measures of systolic and diastolic function parameters.Conclusions:These data are consistent with the presence of an alteration in neural modulation of heart period in HCM patients, noninvasively detectable by continuous 24 hour HRV a

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00289.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Background:Abnormal autonomic control of heart rate is associated with an inreased risk of cardiovascular morbidity and mortality. There are few population‐based reports on the interindividual variation and determinants of cardiac control in healthy middle‐aged males.Methods:Autonomic modulation of heart rate was studied in 172 randomly selected middle‐aged males (mean age 50 ± 6 years) by measuring the heart rate variability (HRV), which was related to life style data, personality type, blood pressure, lipid analyses, results of the 2‐hour glucose tolerance test and left ventricular function.Results:Large interindividual variation was observed in the standard deviation of RR intervals (mean 59 ± 20 ms; coefficient of variation (CV) 34%) compared to variation of the average heart rate (mean 76 ± 11 beats/min, CV 14%). When analyzed as normalized units, marked interindividual variation was observed in the low (CV 16%) and high frequency component (CV 37%). The total power of HRV had significant indirect univariate correlations with age, blood pressure, body mass index, 2‐hour blood glucose level, fasting and 2‐hour serum insulin levels, triglyceride level, and a direct correlation with left ventricular fractional shortening. In a multiple regression analysis, the total power of HRV was best predicted by age (β=−0.27, P = 0.0002), followed by the fractional shortening (β= 0.25, P = 0.0004), systolic blood pressure (/3 =−0.2 1, P = 0.005) and 2‐hour insulin level (β=−0. 9, P = 0.01).Conclusions:Overall HRV has a wide interindividual variation and is related to several cardiovascular risk factors, perhaps contributing to the observed association between low HRV and cardiovascular mortality. Normalized units of HRV reflecting sympathovagal balance are unrelated to age, life style, or ca

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00290.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Background:The study evaluated interobserver differences in the classification of the T‐U wave repolarization pattern, and their influence on the numerical values of manual measurements of QT interval duration and dispersion in standard predischarge 12‐lead ECGs recorded in survivors after acute myocardial infarction.Methods:Thirty ECGs recorded at 25 mm/s were measured by six independent observers. The observers used an adopted scheme to classify the repolarization pattern into 1 of 7 categories, based on the appearance of the T wave, and/or the presence of the U wave, and the various extent of fusion between these. In each lead with measurable QRST(U) pattern, the RR, QJ, QT‐end, QT‐nadir (i.e., interval between Q onset and the nadir or transition between T and U wave) and QU interval were measured, when applicable. Based on these measurements, the mean RR interval, the maximum, minimum, and mean QJ interval, QT‐end and/or QT‐nadir interval, and QU interval, the difference between the maximum and minimum QT interval (QT dispersion [QTD]), and the coefficient of variation of QT intervals was derived for each recording. The agreement of an individual observer with other observers in the selection of a given repolarization pattern were investigated by an agreement index, and the general reproducibility of repolarization pattern classification was evaluated by the reproducibility index. The interobserver agreement of numerical measurements was assessed by relative errors. To assess the general interobserver reproducibility of a given numerical measurement, the coefficient of variance of the values provided by all observers was computed for each ECG. Statistical comparison of these coefficients was performed using a standard sign test.Results:The results demonstrated the existence of remarkable differences in the selection of classification patterns of repolarization among the observers. More importantly, these differences were mainly related to the presence of more complex patterns of repolarization and contributed to poor interobserver reproducibility of QTD parameters in all 12 leads and in the precordial leads (relative error of 31%–35% and 34%–43%, respectively) as compared with the interobserver reproducibility of both QT and QU interval duration measurements (relative error of 3%–6%, P<0.01). This observation was not explained by differences in the numerical order between QT interval duration and QTD, as the reproducibility of the QJ interval (i.e., interval of the same numerical order as QTD was significantly better (relative error of 7.5%–13%, P<0.01) than that of QTD.Conclusions:Poor interobserver reproducibility of QT dispersion related to the presence of complex repolarization patterns may explain, to some extent, a spectrum of QT dispersion values reported in different clinical studies and may limit the clinical utilit

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00291.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Background:Although symptoms suggestive of cardiac arrhythmias are a common event in clinical routine, a standardized diagnostic approach is not available.Methods:The diagnostic accuracy of electrocardiographic self‐recording was evaluated in 115 consecutive patients presenting with symptoms suggestive of cardiac arrhythmias.Results:In 44.3% of cases, self‐recording showed cardiac arrhythmias to be the cause of the patients' symptoms; in 35.7% cardiac arrhythmias were ruled out as the cause of the patients' symptoms. Only 6.2% of the recordings were not evaluable for technical reasons.Conclusion:ECG self‐recording is more effective in detecting arrhythmias than other methods for arrhythmia monitoring. Therefore, it should be used as a first line study in patients likely to have symptomatic arrhyt

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00292.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Background:The implementation of signal‐averaged analysis in the Holter recording may increase cost‐effectiveness and enables further insights into pathophysiological links between arrhythmia genesis and time related modulating factors. This study assesses the feasibility of a new digitizing long‐term recorder system to perform a signal‐averaged analysis and compares the data with the results achieved by an established bedside real‐time recording system.Methods:The study was performed prospectively in 22 patients. The digital recorder FD‐3 obtained a 3‐channel 24‐hour Holter monitoring. For the signal‐averaged ECG analysis, a template averaging was achieved in 5‐minute periods. The interpolated sampling rate was 1024 Hz. The signal‐averaged ECG by bedside real‐time system was performed using the Predictor system. At 25–250 Hz and 40–250 Hz band‐pass filter, 4 FD‐3 epochs acquired in a 6‐hour interval were chosen and the mean values of QRS, root mean square (RMS), and low amplitude signal (LAS) were compared with the data obtained by one Predictor measurement.Results:The regression analysis shows a positive correlation between the FD‐3 and Predictor data of QRS, RMS, and LAS at both filter settings except for LAS at 25–250 Hz. Regarding the late potential classification, at 25–250 Hz 4 of 22 (18%) FD‐3 and Predictor classifications were not coherent and at 40–250 Hz only 2 of 22 (9%) classifications did not correlate.Conclusions:The FD‐3 recorder is feasible to perform a signal‐averaged ECG analysis. Especially at 40–250 Hz, the late potenti

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00293.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Background:The effect of acute myocardial infarction and regional ischemia on the frequency content of the ECG signal has been described by several investigators. In the present study, the feasibility of assessing changes in the QRS spectrum during exercise testing, and whether these changes are related to the occurrence of ischemia were examined.Methods:Spectral analysis of the high resolution ECGs from leads V3, V4, V5, and V6were performed in two groups of male subjects before, during, and following treadmill exercise testing. Group A included 32 coronary artery disease (CAD) patients, with arteriographically proven>75% obstruction of at least two main coronary arteries, and group B included 30 healthy subjects, without history or symptoms of CAD. Signal averaging and filtering techniques were used in order to enhance the signal‐to‐noise ratio of the recorded ECGs. The power spectrum of the averaged QRS waveform for the different stages of the exercise testing was computed using a Fast Fourier Transform, and the slope of the linear regression line was found in the frequency range 7.81–249.92 Hz on the plot of log((amplitude)2) versus log(frequency).Results:Regression line slopes immediately after peak exercise were significantly lower for the CAD group than for the healthy subjects in 3 of the 4 examined leads. No significant changes in slopes were found between the two groups at rest or during late recovery. Comparing the differences between slopes at different stages of the test revealed that the difference between postexercise slope and rest slope has lower mean values for the CAD group in all four leads, with a significant difference in lead V6, and for the difference between postexercise slope and recovery slope, lower mean values were found for the CAD group in all four leads, with a significant difference in V5 and V6.Conclusions:These findings indicate that ischemic changes affect the power spectrum of the QRS complex, and result in a steeper regression line on a log‐lo

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00294.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Background:Abnormal autonomic nervous function (ANF), such as an enhanced sympathetic tone and an attenuated parasympathetic tone, have been shown in patients with congestive heart failure (CHF).Methods:We examined the effects of captopril and metoprolol on autonomic nervous function and ventricular arrhythmias in patients with idiopathic dilated cardiomyopathy (DCM), using 24‐hour ambulatory electrocardiographic monitoring and power spectral analysis of heart rate variability. Twenty‐one patients (pts) with idiopathic DCM (54 ± 15 years [mean ± SDI) were allocated to three groups: a captopril group (8 pts); a metoprolol group (7 pts); and a control group (6 pts). Power spectra were quantified in high (HF) and low frequency power (LF), and natural logarithmic values of HF (In(HF) and LF/HF (In (LF(HF]) were used as indices of parasympathetic and sympathetic nervous activities, respectively.Results:In the captopril and the metoprolol groups, there was a significant increase in In(HF) (P<0.05), a trend of decrease in ln(LF/HF), and an improvement of ventricular arrhythmia (VA). In contrast, no significant change was found in any of In(HF), In (LF/HF), and VA in the control group.Conclusion:We conclude that both captopril and metoprolol have beneficial effects on ANF and VA, and the restored autonomic balance and the improvement of VA correlate to each

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00295.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Objective:Arrhythmogenic right ventricular dysplasia up to now is a rare cardiomyopathic entity with certain difficulties in clinical definition of diagnostic criteria. In 42 patients with major and minor criteria of arrhythmogenic right ventricular dysplasia and 25 patients with idiopathic ventricular arrhythmia, the role of conventional ECG in the diagnosis of arrhythmogenic right ventricular dysplasia was reevaluated.Methods:In standard 12‐lead ECG, QRS duration was measured in limb lead D1, and in V1‐V6. A ratio of the sum of right (V2+ V3) and left (V4+ V5) was calculated. T wave inversions, Epsilon wave, and mechanisms of advancing right bundle branch block were analyzed.Results:In 39 out of 42 patients (93%) with the diagnosis of arrhythmogenic right ventricular dysplasia, a ratio of right and left precordial QRS duration of>1.2, a maximum right precordial QRS duration of>100 ms in 10 cases (26%) and>110 ms in 29 cases (74%) could be found. Incomplete right bundle branch block with right precordial T inversions was found in one case. The ECG in two patients revealed a precordial R/S transition in V1or V2; in all other cases, R/S transition was localized in V3or V4. R peak time was normal (<0.04 s) in all cases, a “notching” or “slurring” of the S wave was striking in 16 cases. T wave inversions were found in 27 cases and definite Epsilon wave in only one case. Although incomplete right bundle branch block and certain preforms could also be disclosed in four patients with idiopathic right ventricular outflow tract (RVOT) tachycardia, localized right precordial QRS prolongation could be excluded in all but one of these cases. Localized right precordial QRS duration prolongation in one case was probably due to a rotation of the heart with a precordial R/S transition between V1and V2.Conclusion:Localized right precordial QRS prolongation in a normal precordial R/S transition: (a) seems to be the most important aspect of arrhythmogenic right ventricular dysplasia at conventional ECG, with a sensitivity of 93% and a specificity of 96% in order to distinguish idiopathic RVOT tachycardia; (b) can appear with (64%) or without (36%) secondary T wave inversions; and (c) is due to a “parietal” block sparing the specialized co

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00296.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Background:The pathogenesis of the occurrence of late potentials (LP) has not been fully elucidated. Deletion polymorphism in the Angiotensin I‐converting enzyme (ACE) gene may relate the myocarclial remodeling after the myocardial infarction (Ml). The purpose of this study was to evaluate the significance of ACE gene polymorphism for the occurrence of LPs after Ml.Methods:A 287 base pair (bp) insertion/deletion polymorphism in intron 16 of the ACE gene was determined by polymerase chain reaction and LPs were also examined by signal‐averaged EGC in 136 patients with Ml. Polymorphism of the ACE gene was characterized by three genotypes: II, ID, and DD. Signal‐averaged ECG were recorded using X, Y, Z leads and LP were defined by time‐domain analysis as low amplitude potentials exceeding 20 ms after the QRS‐end and filtered QRS>115 ms.Results:Positive LPs were noted in 40 of 136 patients with Ml. No differences could be detected between patients with LP‐positive and LP‐negative for the location of Ml, the success rate of reperfusion therapy, and left ventricular end‐diastolic volume (126 ± 40 vs 113 ± 43 mL/m2). In patients with LP‐positive compared with those in LP‐negative, filtered QRS was significantly higher (135 ± 8 vs 107 ± 8 ms), left ventricular ejection fraction was lower (47 ± 12 vs 54%± 11 %), and peak was higher (3602 ± 2928 vs 2614 ± 2360 IU/L). The frequency of ACE/DD genotype was associated with patients with LP‐positive (18 of DD, 18 of ID, and 4 of II for patients with LP‐positive, while 25 of DD, 42 of ID, and 29 of II for patients with LP‐negative). In the study population, the ACE / DD genotype was associated with patients with LP‐positive when compared with the ACE ID&II genotype (x2= 4.7, P = 0.03).Conclusion:ACE/DD genotype of the ACE gene may be associated

ISSN:1082-720X    

DOI:10.1111/j.1542-474X.1996.tb00297.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY