SEARCH · PubMed Health

Results for “ECG”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources

PubMed1990

[The diagnosis of silent myocardial ischemia. The problems of false-positive findings in the exercise ECG and long-term ECG].

In the case of a disease that produces no complaints, such as silent myocardial ischemia, it is of particular importance not to diagnose--or even to treat--a "pseudo-disease" in a patient with false-positive findings. In assessing whether a finding is false-positive or not, there is no "gold standard" for 24-hour ECG monitoring, since no other technique is capable of detecting transient attacks of ischemia occurring at any time during the day or at night. If only the ECG finding is positive, however, a second independent method is required to confirm the diagnosis. In this it must be remembered that all causes of false positive findings known in the case of exercise ECG also apply to the 24-hour ECG, and that when patients in whom the pre-test probability in accordance with the risk profile is low, the number of false-positive findings is likely to be very high. For these reasons, the 24-hour ECG cannot be recommended as a screening procedure for the diagnosis of ischemic heart disease.

Bayes Theorem↗

PubMed1983

[Clinical significance of the corrected orthogonal ECG (Frank) in comparison with conventional ECG for the detection of coronary heart disease].

The clinical evidence of the two derivation systems is of the same value concerning the recognition of the coronary heart disease. Their information range does not significantly differ from each other statistically, when scale and vectorial parameters of the corrected orthogonal ECG after Frank are taken into consideration. But in individual cases clear differences may be present, such as the insufficient representation of localized precordial potential losses in the corrected orthogonal ECG. With the help of the discriminance analysis the high number of falsely negative findings of the ECG after resting can be reduced from about 45% to 15% to 20%. Within a diagnostic stage programme from the recognition and care of particularly endangered patients with coronary heart disease the corrected orthogonal ECG is suited, when a discriminance-analytic valuation with scale and vectorial parameters is made. In contrast to the conventional ECG it has the advantage that it is more rapidly and less expensively to be evaluated by computers.

Adult↗

PubMed2006

A meta-analysis of ECG data from healthy male volunteers: diurnal and intra-subject variability, and implications for planning ECG assessments and statistical analysis in clinical pharmacology studies.

OBJECTIVE: To evaluate the innate variability in key electrocardiography (ECG) parameters from clinical pharmacology studies. METHODS: Meta-analysis of ECG data from seven clinical pharmacology studies in healthy male volunteers using model building and stepwise multiple regression analyses. RESULTS: Data from 115 male subjects provided over 2,000 observations for all key ECG parameters from baseline (Day-1) and placebo treatment periods (Day 1). Only heart rate and uncorrected QT showed clear and marked changes over the day. QTcB had greater variability compared to QTcF. 1.4% of QTcB and 0.7% QTcF observations were >430 ms and 0.1% of QTcB and 0% of QTcF observations were >450 ms. We estimated that 8.9% of subjects would have at least one out of eight post-observation QTc value in the range 430-450 ms [assuming QTc mean 385 ms, standard deviation (SD) 20 ms] due to intrinsic variability alone. Time-matched within-subjects observations demonstrated that the SD between measurements taken 1 h apart was less than seen with a longer interval, but there was little increase in variability beyond 1 h. The probability of observing an increase in QTc of 30-60 ms in a subject was estimated as 3.0% and 21.8% for one and eight post-dose observations, respectively. The greater the number of observations used to define baseline the narrower the spread; for QTcF the SD of the baseline value was 17.1 ms for a single assessment, 13.3 ms for the mean of three assessments, and 13.2 ms for the mean of all Day-1 assessments. CONCLUSIONS: The spontaneous variability in QTc measurements must be taken into account when designing studies and interpreting analyses of ECG data. The categorical analysis of QTc change of 30-60 ms is unlikely to be of any additional value to analyses of central tendency. For standard early clinical pharmacology studies, QTcF should be chosen as the primary correction method, while the mean of three measures taken in the afternoon and evening of Day-1 and pre-dose Day 1 should provide a reliable and representative baseline assessment.

Adolescent↗

PubMed2002

Multislice helical CT of the heart with retrospective ECG gating: reduction of radiation exposure by ECG-controlled tube current modulation.

Our objective was to evaluate image quality and radiation exposure of retrospectively ECG-gated multislice helical CT (MSCT) investigations of the heart with ECG-controlled tube current modulation. One hundred patients underwent MSCT scanning (Somatom VolumeZoom, Siemens, Forchheim, Germany) for detection of coronary artery calcifications. A continuous helical data set of the heart was acquired in 50 patients (group 1) using the standard protocol with constant tube current, and in 50 patients (group 2) using an alternative protocol with reduced radiation exposure during the systolic phase. The standard deviations (SD) of predefined regions of interest (ROIs) were determined as a measure of image noise and were tested for significant differences. There was no significant difference between group 1 and group 2 with respect to image noise. Radiation exposure with and without tube current modulation was 1.0 and 1.9 mSv ( p<0.0001), respectively, for males and 1.4 and 2.5 mSv ( p<0.0001), respectively, for females; thus, there was a mean dose reduction of 48% for males and 45% for females, respectively. The ECG-controlled tube current modulation allows significant dose reduction when performing retrospectively ECG-gated MSCT of the heart.

Calcinosis↗

PubMed1975

Semi-automated ECG processing: A simple method to improve efficiency in ECG laboratories.

A method to expedite processing of electrocardiograms (ECGs) is described. The hardware configuration utilizes conventional equipment, and the ECG data is stored in magnetic data cards. The electrocardiographer's interpretation is made using a specially developed code of 253 diagnostic statements of 2 to 9 words each. A minicomputer converts the code into full alpha-numeric description and 2 characters into English statements. The diagnostic print-out appears in the same page as the reproduction of the original ECG data. This system has significantly reduced the ECG processing time, freed manpower to increase availability of technicians and decreased the size of permanent files.

Diagnosis, Computer-Assisted↗

PubMed2004

Atrial fibrillatory wave characteristics on surface electrogram: ECG to ECG repeatability over twenty-four hours in clinically stable patients.

INTRODUCTION: Fibrillatory waves on the surface ECG have been scrutinized to allow inferences about underlying mechanisms and pathophysiology, based on the premise that fibrillatory waves do not vary "randomly" but provide a consistent reflection of the underlying state of the atria in an individual patient. This premise is untested. METHODS AND RESULTS: Ten standard ECGs were recorded over a 24-hour period in each of 20 clinically stable inpatients with atrial fibrillation. After QRS-T cancellation, the remainder fibrillatory waves were analyzed. Interpatient versus intrapatient differences in fibrillatory wave characteristics were evaluated by analysis of variance (ANOVA). The fibrillatory wave peak-to-peak amplitude of all the patients ranged from 0.06 to 0.35 mV, whereas 1 SD of the amplitude for each patient ranged from 0.004 to 0.053 mV. Short-term peak frequencies of all the patients ranged from 4.6 to 8.0 Hz, whereas 1 SD for each patient varied from 0.2 to 0.5 Hz. For these and all other parameters tested, interpatient differences were significantly greater compared to intrapatient differences (P < 0.0001). CONCLUSION: Fibrillatory wave characteristics are repeatable from ECG to ECG over 24 hours for clinically stable patients, whereas substantial differences are present between patients. Further study of the relationship of such characteristics to pathophysiology and management decisions is valid and warranted.

Aged↗

PubMed1999

Mechanism of induction of follicular atresia after equine chorionic gonadotrophin (eCG) antisera treatment in hypophysectomized eCG-injected hamster model: possible involvement of c-myc and cdc25.

An intracellular mechanism of induction of apoptosis of granulosa cells implicated in the initiation of experimentally induced atresia of ovarian follicle in hypophysectomized eCG-injected hamster followed by eCG-antisera treatment is proposed. Induction of atresia after withdrawal of injected eCG by eCG-antisera treatment is possibly caused by inadequate level of the gonadotropin-induced growth factor that results in apoptosis of granulosa cells associated with the activation of c-myc requiring cdc25A.

Animals↗

PubMed1989

[Safe placement of atrial shunt catheters using intracardiac ECG. Initial experiences with a new ECG adapter system in 33 patients].

In 1960 Robinson inaugurated the method of placing atrial shunt catheters with the help of intracardiac ECG monitoring. Vulnerability to artifacts and problems with electrical safety (which have since been solved) led to its disuse. A newly developed ECG adapter proved free from artifacts and was practicable in 33 patients. 31 shunts were correctly placed without requiring time-consuming radiography. 2 extracardiac false positions were clearly identifiable by means of true negative results, which after correction showed a typical atrial ECG. The ECG method is compared with 9 other positioning methods. It seems to be superior to the conventional chest x-ray and equal to fluoroscopy. However, the method is not on a par with sophisticated measuring techniques such as intracardiac pressure monitoring or intravasal sonography.

Adolescent↗

PubMed2006

[ECG and 24-hour ECG findings in athletes of static and dynamic disciplines].

UNLABELLED: Endurance sports are associated with structural and functional changes in the myocardium. Physiologic changes representing cardiac adaptation to training are termed "athletic heart". THE AIM: We compared the incidence of arrhythmias and conduction abnormalities in athletes of static and dynamic sports using resting and 24 hour electrocardiography. We also studied the effect of physiologic left ventricular hypertrophy on the incidence of arrhythmias and conduction abnormalities in athletes, as well as of training duration on electrocardiographic parameters. MATERIAL AND METHODS: We enrolled 40 male athletes of static and 40 of dynamic sports, as well as 30 normally active males. A 12-lead resting ECG, 24 hour ECG, and echocardiography were done. RESULTS: The resting heart reate in athletes was significantly slower (p < 0.0001). No intervals longer than 3s, bundle branch or atrioventricular blocks were disclosed. The finding of left ventricular bypertrophy and training duration had no significant effect on the presence and number of supraventricular and ventricular arrhythmias or blocks. CONCLUSION: Resting ECG, echocardiography, and 24 hour ECG provide valuable cardiologic information in athletes. The heart rate was slower in all athletes and the PQ interval was longer as compared with controls. No serious arrhythmias or conduction abnormalities were noted. The duration of training and the presence of myocardial hypertrophy had no effect on electrocardiographic parameters.

Adult↗

PubMed1991

[ECG changes in hypertrophic cardiomyopathy in children (data of routine and circadian ECG)].

Analysis is made of the routine and circadian ECG in 32 children with hypertrophic cardiomyopathy. The signs of myocardial hypertrophy of some or other parts of the heart were discovered in 29 children (90.6%). The signs of left ventricular hypertrophy were the most suggestive ones, whereas the signs of left atrial hypertrophy and right heart hypertrophy were observed less frequently. The use of the daily ECG monitoring allowed rhythm and conduction disorders to be revealed in 30 children (93.8%). It should be mentioned that in patients with the obstructive form of the disease, the signs of myocardial hypertrophy and heart arrhythmia on the ECG occurred much more often than in children suffering from the non-obstructive form. In accordance with the observations, prognostically unfavourable disorders of heart rhythm are not characteristic of children, they occur rarely, being primarily seen in the obstructive form of the disease. The daily ECG monitoring not infrequently allows the identification of heart arrhythmias and transitory disorders of conduction, which cannot be recorded on routine electrocardiography.

Adolescent↗

PubMed1990

Methodology of ECG interpretation in the Dalhousie program; NOVACODE ECG classification procedures for clinical trials and population health surveys.

The Dalhousie ECG Program was designed specifically for the needs of epidemiologic studies, health surveys, and clinical trials. The program logic is dynamic in that it can accommodate any combination of ECG leads, record length and sampling rate. The NOVACODE module of the program classifies ECGs according to the Minnesota Code, supplemented with new sets of logic criteria for conduction defects, acute myocardial infarction, and serial ECG changes. Improved statistical models are incorporated for enhanced detection of myocardial infarction using the Cardiac Infarction Injury Score, and for quantification of left ventricular mass estimation. It is anticipated that these program improvements will enhance its utility particularly in monitoring progression and regression of cardiac involvement in hypertensive and ischemic heart disease, and in the assessment of the effectiveness of intervention on cardiovascular disease risk factors.

Adolescent↗

PubMed1983

[Prevalence of hyperkinetic arrhythmias in a healthy infantile and adolescent population: correlations between standard ECG, stress test and dynamic ECG].

We evaluated 250 males and 250 females 4 to 17.99 years old, randomly recruited among school-children. Cardiac and other diseases were excluded. All the subjects were studied with a standard ECG iun the standing and supine position for a minute. Three hundred children underwent a treadmill exercise test according to Bruce's protocol and 50 of them had a 24-hour ambulatory ECG monitoring. Sinus arrhythmia was present in 94% of the children in supine position and in 87% of them while they were standing. Only one child had atrial and ventricular premature beats. In a boy a slow ventricular tachycardia was recorded. One child had a WPW and a girl a short PR interval; both were asymptomatic. The exercise test did not induce any arrhythmias and the slow ventricular tachycardia, in the previously mentioned boy was suppressed during exercise and reappeared during the recovery period. The premature beats were greatly reduced in the child who had them during the standard ECG recording. The 24-hour ambulatory ECG monitoring showed only minor degrees of premature atrial and ventricular beats in 24% of the children studied by this method. The maximum number of premature beats was 39 in 24 hours and never exceeded the first grade of Lown's classification. We conclude that a good correlation exists among the three employed techniques in the study of the prevalence of tachyarrhythmias in healthy children. This is the first study that compares these three techniques in a pediatric population.

Adolescent↗

PubMed1977

[Continuous automatic analysis of the ECG with the aid of a computer with cardiosignal input directly from the patient. 1. Isolation of the active signal of the ECG, identification and measurement of its elements].

Because when fed to an on-line computer the ECG information carries a good deal of noise, of prime importance is devising a method for representation and filtration of the useful asignal. It is shown that in order to separate the ueful signal with a protracted direct ECG input from the patient to a computer the use of the proposed modified method of coherent accumulation is advisable. This modification envisages a step-wise solution of the following problems: current diagnosis of arrhythmic contractions exclusion of arrhythmic contractions from the accumulation procedure, automatic search of the normal duration of the RR intervals, equalization of the RRh intervals duration, statistical averaging of the obtained quantum values. The devised modification of the coherent accumulation method, while considerably increasing the noise-immunity of the algorhythm, enables it to effect a direct long-term automatic analysis of the ECG at intensive care units. The identification and measurement of the ECG waves and intervals are done through and automatic selection of the curve elements search zones, finding local maxima and also of the commencement and end of waves by using the method of the "moving window" with an adaptive evaluation of the first signal derivative intensity.

Adolescent↗

PubMed1988

High-resolution ECG on a standard ECG cart.

High-resolution (HI-RES) ECG analysis software and a new front end have been designed for a standard 12-lead ECG cart, MAC-12. The front end acquires orthogonal ECG at 1,000 samples/sec and 1.2 microV/bit and transmits to the cart. The HI-RES software delineates QRS complexes and correlates them with a template in frequency domain to compute an average cardiac complex (P, QRS, and T). This complex is used for analysis of late potentials, bundle of His activity, and detection of coronary artery disease using its high-frequency content. Both time- and frequency-domain methods are implemented for analysis of ventricular late potentials. In the time-domain method, the average beat is bandpass filtered using three lower cutoff frequencies--25, 40, and 80 Hz--with the higher cutoff at 250 Hz. For each of these frequencies, the following features are extracted: RMS voltages in terminal 40 and 50 msec; ventricular activation time; and duration of high-frequency, low-amplitude signals. The frequency-domain analysis examines the spectral contents of the windowed segment of terminal QRS; ST-segment; and a combined segment of QRS and ST. The spectral features include ratios of magnitudes of Fourier coefficients and areas above 20 Hz, dB drop at 40 Hz, and areas after 60 dB offset. Initial testing of this system is complete, and it is due for clinical trials soon.

Bundle of His↗

PubMed2000

Recurrent ischemia during continuous 12-lead ECG-ischemia monitoring in patients with acute coronary syndromes treated with eptifibatide: relation with death and myocardial infarction. PURSUIT ECG-Ischemia Monitoring Substudy Investigators. Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy.

Computer-assisted continuous monitoring of the ST-segment allows detection and quantification of recurrent ischemia in patients with acute coronary syndromes. In a substudy of the PURSUIT (Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy) trial, this technique was used to evaluate the effects of the glycoprotein IIb/IIIa inhibitor eptifibatide on the incidence and severity of recurrent ischemia, and to investigate the relationship between recurrent ischemia and the occurrence of subsequent death or myocardial (re)infarction. A total of 258 patients with unstable angina or evolving myocardial infarction without ST elevation were monitored for 24 hours during infusion with either eptifibatide or placebo with a computer-assisted 12-lead ECG-ischemia monitoring device. Recurrent ischemic episodes were identified by an automated computer algorithm. Two hundred and sixteen patients (84%) had ECG recordings suitable for analysis. Ischemic episodes were detected in 35 (33%) of the 105 eptifibatide patients and in 32 (29%) of the 111 placebo patients (not significant). No difference in ischemic burden was apparent between both treatment groups. Patients who exhibited 2 or more episodes of recurrent ischemia more frequently died or suffered a myocardial infarction, both at 7 and 30 days, as well as through the 6-month follow-up. A greater ischemic burden was significantly related to adverse outcome during the 6-month follow-up period. Real-time computer-assisted continuous multilead ECG-ischemia monitoring may help to identify patients with unstable coronary syndromes at increased risk of adverse outcome and, thus, allow for better prognostic triage and more appropriate selection of therapeutic strategies. Integration of these systems in coronary care units and emergency wards should, therefore, be recommended.

Adult↗

PubMed1994

Effects of digitalis, anti-anginal drugs and arterial hypertension on the relationships between exercise ECG and angiocardiographic variables and on the diagnostic accuracy of exercise ECG in patients with coronary heart disease.

We have previously found a statistically significant correlation between some exercise ECG variables and angiocardiographic scores used to evaluate the extent and type of coronary heart disease (CHD). In the present study we examined the effects of digitalis, beta-adrenergic blockers, slow release nitrates, calcium channel blockers, presence of arterial hypertension (AHT), and angiocardiographic changes on the exercise ECG variables. The effects of drugs and AHT were small as compared to the effects of the angiocardiographically detected pathological changes caused by the CHD. Sensitivity and specificity of the exercise ECG ST criteria in identifying patients with an angiocardiographic criterion indicating coronary insufficiency were not much different in the whole group and in the subsets with AHT or medication with digitalis and anti-anginal drugs.

Adrenergic beta-Antagonists↗

PubMed1989

[Comparative study of the ECG exercise test and ambulatory ECG monitoring after recovery from acute myocardial infarction].

Early ECG exercise tests (EET) and ambulatory ECG monitoring (AEM) were performed in 42 patients surviving AMI in order to determine the sensitivity of the two methods for detecting ST-segment deviation and arrhythmias. 23 patients had ST changes during EET and AEM. Of them, 21 patients had ST changes induced by EET and 10 were recorded by AEM. The more the ECG leads used for monitoring during and after EET, the higher the percentage of patients with ST changes will be. There were 2 cases with ST changes found in AEM only. All the 6 patients who had ST elevations during EET had an anterior infarction and echocardiograms did show that they had left ventricular aneurysms or abnormal ventricular wall movement. AEM recorded ventricular premature beats (VPBs) in 37 cases (88.0%), while EET induced VPBs in 8 patients. The 42 patients were followed up for an average time of 6 +/- 1.7 m. (3.4 to 9.3 m.) Cardiac death occurred in 2 cases. One of them had horizontal ST depression of 3 mm during EET, the other had a negative EET but multifocal VPBs during AEM. It is concluded that for detecting ST changes EET is more sensitive than AEM, while VPBs are more frequently found in AEM than in EET. The authors are of the opinion that for better, prediction of the prognosis of patients after AMI, it is preferable to have early EET in combination with AEM.

Aged↗

PubMed1985

[To what extent do indications for or questioning of the 24-hour ECG in ambulatory practice correlate with established ECG findings?].

In 1312 patients the Holter 24-h ECG method served to detect 3190 abnormalities of the cardiac rhythm (mean 2.43 different types of arrhythmia per patient), and were classified into 14 arrhythmia groups. The main groups of indications for Holter ECG were classified as follows: palpitation; syncopes, dizziness; life-threatening arrhythmias. The positivity of the test correlated extremely well with the severity of the clinical symptoms: if syncope or dizziness were the indications for Holter ECG, abnormalities were found in 57%; if life-threatening arrhythmias were suspected, abnormalities were found in 54.7% of the patients.

Arrhythmias, Cardiac↗