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PubMed1979

[Identification of the sinus potential in man by endocavitary electrocardiography. Identification criteria, preliminary results].

The potential of the sinus node was recorded in 24 patients by endocavitary electrocardiography using the same equipment as for usual electrophysiological investigation. The sinus node potential is a slow wave which starts progressively, has a rounded peak and precedes the endocavitary atrial activation and the surface P wave, and is relayed at an acute angle to the high amplitude deflection of atrial depolarisation. In some specially selected recordings it is easy to confirm the sinus origin of this slow wave where its preatrial position may be defined by the fixed relation of the S-P interval and by the variability of the T-S interval. Usually it is necessary to use technical manoeuvres (vagal stimulation, premature atrial stimulation) to demonstrate the preatrial behaviour of a potential thought to be of sinus origin. The variability of the sinus potential and the apparent sinoatrial conduction time, is suggestive of a physiological instability of the intrasinus pacemaker. The sinoatrial conduction time measured directly does not seem to exceed 140 ms in normal subjects.

Arrhythmias, Cardiac↗

PubMed1979

[Painless ST elevation with syncope. Diagnosis by continuous electrocardiography].

The aetiology of syncope in a 53 year old man was discovered on continuous ambulatory electrocardiography. A ventricular arrhythmia associated with ST elevation was recorded. It proved resistant to medical therapy and a double aorto-coronary bypass graft was performed. Post-operative Holter monitoring showed surgery to have been effective.

Arrhythmias, Cardiac↗

PubMed2002

[Usefulness of left ventricular opacification with intravenous contrast echocardiography in patients with asymptomatic negative T waves on electrocardiography].

OBJECTIVES: Patients with electrocardiography (ECG) abnormalities sometimes present without obvious symptoms or abnormal physical findings. In some cases, echocardiography fails to reveal abnormalities compatible with the ECG findings because of poor echocardiographic image quality. New intravenous contrast agents now enable opacification of the left ventricular cavity in the clinical setting. The usefulness of left ventricular opacification (LVO) by ultrasonic contrast agent was examined in asymptomatic patients with negative T waves on ECG. METHODS: Thirty-four consecutive patients (23 males, 11 females, mean age 68 +/- 10 years) with negative T waves without symptoms or abnormal physical findings underwent routine transthoracic echocardiography and LVO by intravenous injection of Levovist using harmonic imaging. RESULTS: Without LVO, abnormal echocardiographic findings compatible with the negative T waves were identified in 22 (65%) of the 34 patients. With LVO, the endocardial border of the left ventricle was observed in all patients and findings compatible with negative T waves were detected in 32 (94%) of the 34 patients, which was significantly higher than that without LVO (chi 2 = 9.79, p = 0.0055). Furthermore, LVO revealed additional findings in nine patients such as mural thrombus or apical thinning. In total, LVO revealed abnormal apical findings in 22 patients (65%), which was significantly higher than that without LVO (chi 2 = 10.0, p = 0.0013). CONCLUSIONS: LVO is useful for identifying abnormal findings, especially in the apex in asymptomatic patients with negative T waves on ECG.

Aged↗

PubMedDate not supplied

Exercise electrocardiography.

Treadmill exercise electrocardiography is a test commonly employed to diagnose coronary artery disease and has powerful prognostic value. It is most accurate when the resting ECG is normal, and because of significant limitations in sensitivity and specificity, the test is most useful when the pretest probability of disease is in the intermediate range. The usual criterion for diagnosing myocardial ischemia is horizontal or downsloping ST-segment depression that measures > or = 1 mm (0.1 mv) 0.08 seconds after the J point, and the specificity of this finding is greatly enhanced by the patient's developing typical angina during the test. Sensitivity and/or specificity may be improved by modifications of the ECG-lead system, computer-assisted measurement of more complex exercise-test variables, using test scores that incorporate coronary risk factors, and by adding radionuclide or echocardiographic imaging modalities that assess myocardial perfusion and/or the metabolic or contractile consequence of myocardial ischemia, as well as the electrocardiographic and symptomatic ones.

Contraindications↗

PubMed2002

[New methods of monitoring the fetus during labor--detection of intrapartum fetal hypoxia by electrocardiography].

The biophysical diagnostic methods are an essential element of evaluation of the fetus state in pregnancy and delivery. Nowadays, the applied methods of fetus supervision during labour don't ensure the permanent analysis and they don't deliver diagnostic information about fetus hypoxia. With a view to avoiding the risk of fetus injury and its hypoxia technologies should be developed which allow to make a diagnosis of perils to good fetus condition and detection of intralabor hypoxia. Therefore, enhancing all new methods are indicated, which facilitate the diagnostic in a permanent mode and which allow for hypoxia prediction and the reduction of unjustified medical interferences. One of these methods is fetus electrocardiography.

Diagnosis, Differential↗

PubMed2003

The maximum A posteriori approach to the inverse problem of electrocardiography.

In this paper we investigate the previously proposed maximum a posteriori (MAP) approach to the problem of determining epicardial potentials from measured body surface potentials, a form of the inverse problem of electrocardiography. The MAP inverse approach uses a priori knowledge of the covariances between epicardial electrograms in its estimate of epicardial potentials. However, in practice, this information is not generally available. In this paper we examined the effectiveness of this method when the covariances are estimated using one depolarization sequence and the MAP method is used with these covariances to estimate the epicardial potentials for a different depolarization sequence.

Algorithms↗

PubMed2002

[Role of electrocardiography in the diagnosis of silent myocardial ischemia].

Norman J. Holter attention drew to the possibility to use ambulatory ECG monitoring not only for the diagnosis of arrhythmias but also myocardial ischaemia by already in 1961. It was found that patients with chronic stable angina pectoris have multiple episodes of myocardial ischaemia characterized by transient depressions of the ST segment, very frequently without a clinical correlate. Electrocardiography thus was the first objective method to draw attention to the fact that angina pectoris is associated with approximately one fifth of ischemic episodes of the myocardium in patients with chronic ischaemic heart disease. This was later expressed objectively by further methods which with a different sensitivity and specificity can diagnose current myocardial ischaemia. It was found that developing myocardial ischaemia is gradually manifested within several to tens of seconds by detectable metabolic changes (PET, sampling from the coronary sinus), changes at the level of the microcirculation with impaired perfusion (thalium scan, contrast echocardiography, PET, contrast angiography), impaired diastolic function of the left ventricle (direct assessment of pressures, Doppler echocardiography), regional disorders of left ventricular kinetics (contrast ventriculography, echocardiography, isotope ventriculography). Only after that electrocardiographic signs of myocardial ischaemia develop, in some patients associated with angina pectoris. It is obvious that the diagnosis of myocardial ischaemia by electrocardiographic signs and subjective manifestations is late and not very sensitive.

Angina Pectoris↗

PubMed2002

[The importance of electrocardiography in cardiomyopathies].

The author discusses possibilities and the importance of electrocardiography in different types of cardiomyopathies. ECG plays a fundamental role in particular in hypertrophic cardiomyopathies where it serves for screening. This pertains to fully developed forms as well as to latent morphologically not yet expressed forms and also to some special types of the disease (apical forms). ECG can be a very important method also in right ventricular arrhythmogenic cardiomyopathies (again above all for screening in paroxysmal ventricular tachycardias in left bundle branch block). In other types of cardiomyopathies the importance of ECG is small.

Cardiomyopathies↗

PubMed2002

[The importance of electrocardiography in the development of new drugs--prolonged QT intervals as indicators of adverse effects].

Both experimental animal studies and clinical observations have shown that drugs from various indication areas, such as psychotropic agents and antiarrhythmics can induce disturbances of cardiac rhythm and electrocardiographic abnormalities. Particularly, QT interval prolongation is associated with distinctive polymorphic ventricular tachycardias and often causes syncopes or cardiac arrest that represent a high risk of recurrent events including sudden death. In the last decade, several drugs in different indication areas, possessing these effects were withdrawn from the market and approvals were postponed or even refused. These events led to higher regulatory requirements on the cardiovascular safety of new drugs, with a special emphasis on prolongation of the QT interval. This article reviews the use of preclinical and clinical electrocardiography, as well as the current problems during development of novel drugs and future strategy in clinical studies. Even though ECG proved to be a powerful and reliable tool for detection of cardiac serious adverse effects during development of drugs, it also needs to be used with increased attention in all patients treated with new drugs and drug combinations in clinical and ambulatory practice in order to ensure their safe use in a wide population, as well as in patients with concurrent cardiac risk factors.

Animals↗

PubMed2002

[Electrocardiography in the diagnosis of genetic heart diseases--the Brugada syndrome].

Electrocardiography celebrates its 100th anniversary but is still a useful and widely used examination method in cardiac diseases. Its importance can be demonstrated on its part in the diagnosis of a relatively newly described disease presented in this paper. It is a genetically conditioned anomaly of sodium channels of the cell membrane, called Brugada syndrome. The latter has a typical electrocardiographic tracing--elevations of the ST segment in leads V1-V3 along with a finding reminding of a right bundle branch block, absence of structural cardiac disease and an increased incidence of serious ventricular arrhythmias and sudden arrhythmic death.

Bundle-Branch Block↗

PubMed2002

[Lead systems in orthogonal electrocardiography].

The paper deals with evaluating quality of some orthogonal and pseudoorthogonal electrocardiographic lead systems as Frank lead system, signals derived from standard electrocardiographic leads by Levkov's transform and some signals of the standard 12 lead system that roughly fulfill condition of geometrical orthogonality. The signals of the lead systems were assessed by means of a mathematical criterion of two vector orthogonality which was originally proposed for purposes of electrocardiography and proved by Netusil. Experiments done with signals of the CSE database of short-time rest ECG records have revealed that the best ECG lead orthogonality has been found for signal sets of I-aVF-V2, and I-III-V2 leads, resp. Unfortunately nearly the worst results were obtained for the widely used Frank orthogonal lead system. It means that this lead system can lead (under some specific conditions) to missing diagnostically important information.

Electrocardiography↗

PubMed1992

Slow-release gallopamil evaluated by exercise test and long-term electrocardiography.

The effects of slow-release gallopamil (100 mg b.i.d.) were studied on exercise-induced ST-segment depression as well as on spontaneous myocardial ischemia detected by long-term electrocardiography (ECG) monitoring for 48 h in 26 patients with coronary artery disease and angina pectoris. Eight patients had to be excluded (because of paroxysmal atrial fibrillation in four patients, development of unstable angina pectoris in three patients, and frequent ventricular premature beats in one patient). In the remaining 18 patients, gallopamil led to an increase of work load (W x min) evaluated by bicycle ergometry, paralleled by an increase of exercise duration until the occurrence of ST-segment depression of > or = 0.1 mV in the nonblinded part of the trial. The number of spontaneous episodes of myocardial ischemia during long-term ECG recording, ranging from 0 to 14 during control, decreased in patients with two or more episodes during control, paralleled by a decrease in the total duration of ischemic episodes and a decrease in the ischemic score (duration of episodes x maximal ST-segment depression). During long-term ECG monitoring, we observed asymptomatic episodes of spontaneous second degree atrioventricular block of the Wenckebach type in three patients. No other adverse effects of slow-release gallopamil were observed. Therefore, these preliminary results of the non-blinded protocol confirm the anti-ischemic effects of slow-release gallopamil given 100 mg b.i.d.; however, these promising results will have to be confirmed in the consecutive double-blind, placebo-controlled part of the trial.

Adult↗

PubMedDate not supplied

Contribution of the high amplitude electrocardiography to the detection of ventricular late potentials in several cardiovascular diseases.

The criteria for detection of ventricular late potentials (VLP) by high amplitude electrocardiography (ECG) in the frequency domain were evaluated in 75 patients with cardiovascular diseases, mostly men (85%), with a mean age of 57 years, distributed by disease type into three subgroups: (1) with a history of myocardial infarction (MI)--53 cases; (2) with syncopes, episodes of prolonged ventricular arrhythmias--18 cases; (3) with unobstructive, primary cardiomyopathies--4 cases. Complete clinical examination, standard ECG, continuous 24 hr Holter ECG, high amplitude ECG (Corazonix system) for detection of VLP by analyses in the time domain (TD) and in the frequency one (FD) were performed in all the cases. The VLP incidence was evidently high in all the cases. By association of the analyses in TD and FD, the accuracy of VLP detection increased by 17.3% in the whole group (from 64% to 81.3%). The incidence of severe ventricular arrhythmias (class 4-5 Lown, i.e., doubled and/or trebled ventricular extrasystoles, salvos of unsustained ventricular tachycardia) was evidently higher in the patients with VLP (88% compared with 77% in the absence of VLP), thus demonstrating the presence, in most of the patients studied, of an arrhythmogenic mechanism by ventricular reentry.

Adolescent↗

PubMedDate not supplied

A clinical trial of the effectiveness of water as a conductive medium in electrocardiography.

A clinical trial was conducted in three hospitals to determine if common tap water is suitable for use as a conductive medium in electrocardiography (ECG). It compares two consecutive ECG recordings of 100 patients, the first recordings were obtained with water as the conductive medium, the second tracings used the electroconductive gel Redux Creme. Analysis involved comparison of the height of the R wave in lead V4 and tracing reports from a cardiologist 'blind' to the medium used. Results indicated that there was no statistically significant difference in the conductive ability of the two media. Analysis of the clinical performance of the media indicated that in 82% of the traces water was equal to or better than gel in clarity, and in 90% of traces water was equal to or better than gel in suitability for diagnosis. One implication of the study is the possibility of significantly reducing the cost of ECG procedures while ensuring the quality of tracings remains at a clinically acceptable level.

Electric Conductivity↗

PubMed2003

Model-based analysis of electrocardiography-gated cardiac (18)F-FDG PET images to assess left ventricular geometry and contractile function.

UNLABELLED: This study presents and evaluates a model-based image analysis method to calculate from gated cardiac (18)F-FDG PET images diastolic and systolic volumes, ejection fraction, and myocardial mass of the left ventricle. The accuracy of these estimates was delineated using measurements obtained by MRI, which was considered the reference standard because of its high spatial resolution. METHODS: Twenty patients (18 men, 2 women; mean age +/- SD, 59 +/- 12 y) underwent electrocardiography-gated cardiac PET and MRI to acquire a set of systolic and diastolic short-axis images covering the heart from apex to base. For PET images, left ventricular radius and wall thickness were estimated by model-based nonlinear regression analysis applied to the observed tracer concentration along radial rays. Endocardial and epicardial contours were derived from these estimates, and left ventricular volumes, ejection fraction, and myocardial mass were calculated. For MR images, an expert manually drew contours. RESULTS: Left ventricular volumes by PET and MRI were 101 +/- 60 mL and 112 +/- 93 mL, respectively, for end-systolic volume and 170 +/- 68 mL and 189 +/- 99 mL, respectively, for end-diastolic volume. Ejection fraction was 44% +/- 13% by PET and 46% +/- 18% by MRI. The left ventricular mass by PET and MRI was 196 +/- 44 g and 200 +/- 46 g, respectively. PET and MRI measurements were not statistically significant. A significant correlation was observed between PET and MRI for calculation of end-systolic volumes (r = 0.93, SEE = 23.4, P < 0.0001), end-diastolic volumes (r = 0.92, SEE = 26.7, P < 0.0001), ejection fraction (r = 0.85, SEE = 7.4, P < 0.0001), and left ventricular mass (r = 0.75, SEE = 29.6, P < 0.001). CONCLUSION: Model-based analysis of gated cardiac PET images permits an accurate assessment of left ventricular volumes, ejection fraction, and myocardial mass. Cardiac PET may thus offer a near-simultaneous assessment of myocardial perfusion, metabolism, and contractile function.

Adult↗

PubMed1992

[High-resolution electrocardiography evaluation of late potentials. A comparison between Frank XYZ orthogonal leads and standard precordial electrocardiographic leads].

High-resolution electrocardiography has been used as a non-invasive method for the study of delayed potentials in order to evaluate the risk of the onset of ventricular arrhythmia first in ischaemic cardiopathy and then in various cardiopathies, generally using XYZ orthogonal derivations. The aim of this study was to compare the results obtained with those using standard precordial leads, in particular V4 and V6 leads. A group of 28 patients, males and females, aged between 15 and 55 years of age, was examined. All patients were suffering from different cardiopathies. Subjects with delayed right and left ventricular activation on the surface ECG tracing were excluded from the study. A 60-200 Hertz bandpass filter and time averaging of 300 consecutive complexes were used to analyse tracings. Dual recordings were performed for each patient. The following parameters were examined: total duration of filtered QRS complex and root-mean-square voltage of potentials in the last 40 msec of filtered QRS (RMS). In particular, the comparison between RMS using Frank's method and those obtained using V4 and V6 precordial leads provided a coefficient of correlation of r = 0.91 with p < 0.001 and r = 0.92 with p < 0.001 respectively, and the comparison between QRS obtained using the same method and that obtained using V4-V6 precordial leads gave a coefficient of correlation of R = 0.80, p < 0.001 and r = 0.77 and p < 0.001 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

[100 years' of clinical electrocardiography].

In 1903 Willem Einthoven published in Pflügers Arch his classic article on the investigation of human electrocardiogram by his string galvanometer. Many historians of medicine, Einthoven also marked that publication as the beginning of clinical electrocardiography. Many investigators like Galvani, Manteucci, Kölliker, Müller, Lipmann, Waller, Ader, Einthoven, Lewis, Wilson and others participated in creation and development of electrocardiogram. From that time electrocardiogram quickly became, and has remained the most essential diagnostic laboratory tool in investigation of heart diseases. The aim of this article is to remind us of the beginning of this part of cardiology 100 years ago.

Electrocardiography↗

PubMed2003

[Concealed phenomena in electrocardiography].

Concealed phenomena in electrocardiography are events which, having no direct effect on the electrocardiogramme, nevertheless change the following sequences giving rise to very unusual appearances. They are diagnosed by deduction. First of all, there is concealed anterograde or retrograde conduction in the AV node, the consequences of which are either a block or the suppression of an escape rhythm or even facilitation of the transmission of activation. Concealed conduction is also possible in the Bundle of His and its branches, explaining the frequency of dependent blocks and aberrant conduction. There is also concealed conduction in accessory pathways. The second form is concealed rhythms: hisian extrasystoles giving rise to pseudo A-V block, and concealed extrasystoles and parasystoles. With temporary pacing of tachycardia, it has finally been possible to describe "visible" concealed phenomena, not on the surface but on the endocavitary electrogramme.

Arrhythmias, Cardiac↗