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PubMed1981

[Dynamic electrocardiography for identification of temporally altered activity in pacemakers (author's transl)].

Four cases of subjects with implanted pacemakers are reported. The patients temporarily presented suspected symptoms of altered activity of the pacemakers. On the other hand usual tests demonstrated a regular activity of the pacemakers. The dynamic electrocardiography, by a regular registration during 24/48 hours and during usual working, documented; once a partial hole in the circuits of the generator, twice a partial break of the catheter, once a displacement. It is underlined the importance of dynamic electrocardiography to identify temporarily altered activity of pacemakers, undiagnosticable by disposable usual tests.

Aged↗

PubMed1994

The antihypertensive treatment and high-resolution electrocardiography.

After six months of antihypertensive treatment the regression of the initially present myocardial hypertrophy was observed: The decrease in blood pressure values is in correlation with the regression of the left ventricular hypertrophy. No correlation with parameters of high-resolution electrocardiography was noted. In one patient, a deterioration of late potentials was observed. It became more pronounced following the treatment. The monitoring of antihypertensive treatment effects by echocardiography and high-resolution electrocardiography may be therefore considered useful, especially in expected regression of the left ventricular hypertrophy. In individual cases of very outstanding regression, there exists the potential possibility of the process, resulting in the risk of arrhythmogenic substrate formation and subsequent generation of dysrhythmias.

Electrocardiography↗

PubMed1994

Transesophageal electrocardiography and adenosine in the diagnosis of wide complex tachycardia.

The diagnosis of wide complex tachycardia based on surface electrocardiography can be difficult. Misdiagnosis occurs frequently and is commonly associated with increased morbidity and mortality. We describe a case of wide QRS complex tachycardia in which transesophageal electrocardiography and intravenous adenosine were used to obtain a reliable diagnosis. These are safe and readily available tools for elucidating the mechanism of wide complex tachyarrhythmias in hemodynamically stable patients.

Adenosine↗

PubMedDate not supplied

The renaissance of clinical electrocardiography.

There is a renaissance occurring in the use of electrocardiography as a diagnostic method, and the primary care physician is deeply involved in the new surge of interest. Just as "necessity is the mother of invention," the renewed interest in electrocardiography is demanded because the proper diagnosis and treatment of patients, especially those with cardiac arrhythmias or acute myocardial infarctions, depend on an accurate interpretation of the electrocardiogram.

Clinical Medicine↗

PubMed1993

European Conformance Testing Services for computerized electrocardiography. New procedures and standards.

Performance requirements and national, as well as international, standards for computer-assisted electrocardiography are behind today's technology. Upgrading is urgently needed from a legal point of view, as well as from a technologic point of view. In Europe a new directive on medical devices requires that instruments with a measurement function have to provide the appropriate measurement accuracy and that manufacturers must specify its measurement accuracy. This study addresses the problem. A description for a new testing system for computer-assisted electrocardiography is given. Also, new tools, for example, the Conformance Testing Services database, and minimum performance requirements for testing computer-assisted electrocardiographs are described and discussed.

Calibration↗

PubMed1996

Detection of acute cardiac allograft rejection with high resolution electrocardiography: experimental study in rats.

BACKGROUND AND METHODS: To diagnose early acute cardiac rejection, we evaluated high-resolution electrocardiography in rats. Heterotopic heart transplantations were performed in allogeneic animals, either treated with cyclosporine or untreated, and in syngeneic animals. High-amplification electrocardiograms were recorded daily, under anesthesia, with two intra-abdominal leads. After amplification (x 5000 to 20,000), the electrocardiographic signal was acquired and analyzed with P-Clamp software. We measured the amplitude (millivolts) and duration (milliseconds) of the auriculogram (P wave) and the ventriculogram (QRS wave), the duration of auriculoventricular conduction (milliseconds; PQ interval) and the heart rate. Twenty-five grafted hearts were fully studied in recipients not treated with cyclosporine (allogeneic n = 16, syngeneic n = 9). RESULTS: In the allogeneic group, acute cardiac rejection was always accompanied by an early and progressive increase in P wave duration and PQ interval, whereas an increase in QRS duration was subsequently recorded. No significant change in P wave, PQ interval, or QRS wave duration was recorded in the syngeneic group, which showed no histologic rejection lesions. A decrease in P wave and QRS wave amplitude was recorded in both groups of animals. In the allogeneic group treated with cyclosporine (n = 21), grafted hearts were removed early (4.5 +/- 0.5 days): 10 cardiac grafts were rejected and 11 were not. An increase in P wave duration > or = 20% was associated with mild rejection in most cases. The sensitivity and specificity of this electrocardiographic sign were excellent (100%). The auricular (right and left atria) and the ventricular (right and left ventricles) tissues were evaluated histologically. In the allogeneic groups (n = 26), the histologic lesions during acute rejection were greater in the auricular myocardium than in the ventricular myocardium. Rejection in the atrial and ventricular myocardium was most often differentiated by one degree according to the Billingham classification. CONCLUSIONS: We concluded that acute cardiac rejection in rats is associated with early conduction disturbances in the atrial myocardium which can be shown by high-resolution electrocardiography.

Abdomen↗

PubMed1997

The relative value of exercise-electrocardiography and dipyridamole stress echocardiography for risk stratification early after uncomplicated myocardial infarction. The EPIC (Echo Persantine International Cooperative) Study Group.

BACKGROUND: Rational prognostic algorithm should be developed considering the logical progression of the information as it becomes available to the physician, with clinical data first, ECG data second and stress imaging data last. The aim of the present study was to assess in a clinically realistic fashion the relative prognostic value of exercise electrocardiography test (EET) and dipyridamole-echocardiography test (DET) early after first acute uncomplicated myocardial infarction. METHODS AND RESULTS: Five hundred and forty-seven in-hospital patients (age = 56 +/- 9 years) with recent clinically uncomplicated first myocardial infarction, baseline echocardiographic findings of satisfactory quality, interpretable ECG and capability to exercise underwent a resting 2D echocardiogram, a DET and an EET at a mean of 10 days from the infarction and were followed up for 16.2 +/- 11 months. During the follow-up, there were 17 cardiac deaths, 19 non-fatal myocardial infarctions and 49 unstable angina. When cardiac death was considered as the only significant event, with multivariate analysis, peak dipyridamole Wall Motion Score Index was the only significant predictor (chi 2 = 5.66; p = 0.013; relative risk estimate = 4.7; confidence intervals = 1.35-16.08). In presence of a negative exercise electrocardiography test for both chest pain and electrocardiographic criteria, the death rate was 2%. CONCLUSION: DET provides stronger information in comparison with historical and EET variables. However, a negative maximal EET is sufficient to identify a very low risk subset in whom additional testing may not be warranted.

Cause of Death↗

PubMed1997

[From the history of electrocardiography].

The basis of electrocardiography was established in the innovative years between 1850 and 1930. Men like Waller, DuBois-Reymond, and Einthoven were the innovators of what we today recognize as modern electrocardiography. Others, like Lewis and Bedford, introduced analysis of cardiac arrhythmias, of the S-T segment and the QRS complex. The article gives an overview of this innovative period and its instrumentation.

Electrocardiography↗

PubMed1998

[High-resolution electrocardiography in acute myocardial infarct].

The author starts by highlighting the importance of risk stratification in patients who have survived a myocardial infarction. High resolution electrocardiography, also called signal-averaged electrocardiography (SAECG), appears in this setting as a diagnostic tool that, by providing important information about the way the intraventricular conduction of the electrical impulse is made, contributes to the characterization of the arrhythmogenic substrate, which is the basis of ventricular tachycardia and fibrillation. By resorting to the averaging of the electrocardiographic signal, SAECG enables us to detect ventricular late potentials whenever the analysis of that signal is made in time-domain. Further details, which will enrich the information on ventricular activation, can be obtained if the analysis is made in the frequency-domain (spectral analysis). The importance of detecting abnormalities in the SAECG recordings lies in the fact that those abnormalities are related to the occurrence of ventricular tachycardia and fibrillation, which are responsible for arrhythmic death. After referring to the criteria of positivity of SAECG and its reproducibility, the author approaches the most important part of the paper: the clinical applications of SAECG. After focusing on the interest of the method in noncoronary conditions, its usefulness in patients with acute myocardial infarction is pointed out. The author then mentions the prevalence of abnormalities in SAECG in patients with acute myocardial infarction and emphasizes the interest of the method in risk stratification. The author then presents the results of his Group in what concerns prevalence and prognosis. Finally, the author refers to the application of SAECG in other forms of coronary artery disease besides myocardial infarction.

Electrocardiography↗

PubMed1980

Demonstration of abnormal proximal conduction system by His bundle electrocardiography in a patient with a single ventricle.

His bundle electrocardiography in a patient with a single ventricle and 2:1 block showed the block to be proximal to the His bundle. The sinus node recovery time was normal. In addition, there was suggested evidence of a functionally and/or structurally abnormal accessory pathway. The role of His bundle electrocardiography in a patient with a single ventricle in defining the function of various portions of the conduction system was thus demonstrated.

Adolescent↗

PubMed1985

Arrhythmias in ischemic and nonischemic dilated cardiomyopathy: prediction of mortality by ambulatory electrocardiography.

To test the hypothesis that ventricular arrhythmias detected by ambulatory electrocardiography can stratify mortality risk in patients with ischemic and those with nonischemic dilated cardiomyopathy, clinical, hemodynamic and neurohumoral findings were evaluated in 31 patients. By Kaplan-Meier analysis, the total population had 51% survival at 12 months and 19% survival at 25 months. Subgroups based on peak complexity of ventricular arrhythmias included 9 patients with simple ventricular arrhythmias (peak Lown grades 1 to 3) and 22 patients with complex ventricular arrhythmias (peak Lown grades 4 or 5). Clinical variables and baseline catecholamine levels and renin-angiotensin system activity were similar in the simple and complex arrhythmia subgroups. Patients with simple and those with complex arrhythmias were comparable by all hemodynamic indexes except for a higher mean pulmonary capillary wedge pressure in the complex arrhythmia subgroup. Survival was strikingly related to arrhythmias: mortality was 11% (1 of 9) in the simple ventricular arrhythmia subgroup and 59% (13 of 22) in the complex ventricular arrhythmia subgroup (p less than 0.025 by log-rank test). Twelve patients died suddenly and 2 patients died in circulatory failure, and the risk of death was not affected by the etiology of cardiomyopathy. The higher mortality among the patients with complex arrhythmia could not be explained by the presence of elevated filling pressures alone. Thus, ambulatory electrocardiography can stratify mortality risk among patients with severe ischemic and nonischemic dilated cardiomyopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1997

Impact of culprit lesion morphology on prevalence of provoked myocardial ischaemia in patients with old myocardial infarction. A dipyridamole stress echocardiography, exercise electrocardiography and angiographic study.

We have recently shown that in patients with single vessel disease and no myocardial infarction, a complex plaque morphology makes myocardium more vulnerable to ischaemia during dipyridamole echocardiography testing. Whether coronary lesion morphology in the infarct-related artery in a chronic phase may also modulate prevalence of ischaemia in the same territory remains unknown. In order to determine the possible relationship between culprit lesion morphology in the infarct-related artery and the prevalence of homotopic ischaemia during stress tests, data from high dose dipyridamole echocardiography tests (up to 0.84 mg.kg-1 over 10 min), exercise electrocardiography and coronary angiography from 73 in-hospital patients with a previous myocardial infarction and patent infarct-related single-vessel disease (> or = 50% diameter reduction) were analysed. An angiographic culprit lesion was considered complex (Ambrose classification) when irregular borders, ulcers, thrombus and/or intraluminal lucencies were present. According to angiographic lesion morphology, two groups were identified: Group I, with simple-type culprit lesions; Group II, with complex type culprit lesions. Number of patients (I = 36; II = 37), age (I = 57 +/- II vs II = 55 +/- 9 years), ejection fraction (I = 58.8 +/- II 3 vs II = 56.5 +/- 10.2%), number of Q or non-Q wave myocardial infarctions, prevalence of rest angina (I = 9; II = II) or effort angina (I = 10; II = 10), culprit lesion stenosis severity (I = 57.9 +/- 7.2% vs II = 57.7 +/- 6.2% by computer analysis) and degree of infarct artery anterograde flow (I = 2.64 +/- 0.48 vs II = 2.56 +/- 0.50 by Thrombolysis in Myocardial Infarction definition) did not differ between the two groups (P = ns for all intergroup differences). Dipyridamole echocardiography test-induced ischaemia (considered as new or worsening abnormal wall motion) in the infarct-related artery territory was 25% in Group I and 59% in Group II (P < 0.01). Among positive dipyridamole echocardiography tests, low dose (0.56 mg.kg-1 over the 4 min) positivity occurred in two out of nine Group I patients and in 16 out of 22 Group II patients (22 vs 73%, P < 0.05). Exercise electrocardiography was positive in seven out of 32 Group I patients, and in 16 out of 35 Group II patients (22 vs 46%, P < 0.05). The peak rate pressure product tended to be higher in Group I than in Group II patients (282 +/- 65 vs 257 +/- 65 mmHg x beats.min x 10(2), P = 0.07). Thus, in patients with previous myocardial infarction and a patent infarct-related artery, complex culprit lesion morphology is associated with a higher prevalence of ischaemia and a lower ischaemic threshold during both exercise and dipyridamole stress testing. The morphology of culprit stenosis is important in modulating different stress responses in the chronic phase of myocardial infarction.

Adult↗

PubMed1990

[The clinical application and limitation of electrocardiography].

Electrocardiography (EGG) is one of the most useful methods for diagnosis of the heart diseases, including ischemic heart disease, cardiomegaly and arrhythmias. However, image methods such as echocardiography, CT-scan and MRI for diagnosis of heart diseases developed in the recent several years gave rise to some conflictions between the findings obtained by ECG and the imaging methods. Therefore, the diagnostic criteria of ECG had to be re-examined. The body Surface Map (MAP) with 87 leads on the body surface revealed more circumstantial electric phenomena of the heart than the standard 12-lead ECG and vectorcardiography. However, the MAP needs a lot of time for recording and diagnosis because of its many electrodes. Computer diagnosis adequately developed, and simplification and abbreviation of recording are required. Morphologic disorders of the heart can be diagnosed more adequately by imaging methods such as echocardiography and CT-scan than ECGs. However for the study of arrhythmias, ECGs including standard 12-lead, vector and Holter electrocardiographies, and MAP are almost the only methods now available. Each method of ECG has different characteristics and is widely accepted not only for clinical diagnosis but also research of arrhythmias. In the near future, noninvasive examination from the body surface to reveal a minute electric change of the heart will be expected instead of invasive examinations as His-bundle ECGs.

Arrhythmias, Cardiac↗

PubMedDate not supplied

[Intracavitary electrocardiography. A useful method for checking the correct localization of central venous catheters].

A placement technique for central venous catheters (CVC) using the intracavitary electrocardiography (ICECG) as well as three different connection systems of the CVC to the electrocardiographic monitor are described. The aim of the present study was to evaluate the correct placement of the CVC by this technique with posterior radiologic confirmation being carried out. The study was undertaken in 30 patients connecting a CVC to a negative electrode of the standard lead II and the positive to the left leg. The CVC was advanced and the changes in the morphology of the "P" wave as it passed along the superior vena cava (SVC) to the right auricle (RA) were observed. In 28 of the 30 patients (93.3%) a biphasic "P" wave (right auricle) was achieved with the CVC being thereafter withdrawn until the SVC (this location was radiologically confirmed posteriorly). In 2 patients (6.6%) a biphasic "P" wave was not obtained and an abnormal position of the CVC was radiologically demonstrated at surgery (one in the ipsilateral subclavian vein and the other had a ring within the right subclavian vein impeding progression). The mean time used in the performance of this technique was 220 +/- 40 s. It is concluded that intracavitary electrocardiography is a simple, easy to learn and perform technique which does not delay surgical procedure and it is a reliable method for placing the end of the CVC.

Catheterization, Central Venous↗

PubMed1991

Standards for analysis of ventricular late potentials using high-resolution or signal-averaged electrocardiography: a statement by a task force committee of the European Society of Cardiology, the American Heart Association, and the American College of Cardiology.

Sufficient data are available to recommend the use of the high-resolution or signal-averaged electrocardiogram in patients recovering from myocardial infarction without bundle branch block to help determine their risk for developing sustained ventricular tachyarrhythmias. However, no data are available about the extent to which pharmacological or nonpharmacological interventions in patients with late potentials have an impact on the incidence of sudden cardiac death. Therefore, controlled, prospective studies are required before this issue can be resolved. As refinements in techniques evolve, it is anticipated that the clinical value of high-resolution or signal-averaged electrocardiography will continue to increase.

Analog-Digital Conversion↗

PubMed1997

Signal-averaged electrocardiography in patients with AL (primary) amyloidosis.

One hundred thirty-three patients with biopsy-proven AL amyloidosis were studied with echocardiography, Holter recording, 12-lead electrocardiography, and signal-averaged electrocardiograms. Features from these tests were analyzed in relation to their effect on mortality. Late potentials were more frequent in patients with echocardiographic evidence of cardiac amyloidosis (31%) compared with patients with normal echocardiograms (9%, p < 0.003). One hundred six of the 133 patients died during follow-up, of which 34 were nonsudden cardiac deaths and 33 were sudden deaths. Abnormal echocardiograms and signal-averaged electrocardiograms were each predictive of all-cause cardiac death (p < 0.0001 ) and sudden cardiac death (p < 0.0001). Abnormal signal-averaged electrocardiograms were also independently predictive of sudden death in the subgroup of patients with an abnormal echocardiogram (p < 0.05). Thus late potentials are predictive of sudden death in patients with AL amyloidosis and provide independent prognostic information in patients with echocardiographic evidence of amyloid involvement.

Adult↗

PubMed1997

Prognostic value of thrombolysis, coronary artery patency, signal-averaged electrocardiography, left ventricular ejection fraction, and Holter electrocardiographic monitoring for life-threatening ventricular arrhythmias after a first acute myocardial infarction.

Prognostic studies after acute myocardial infarction (AMI) have mainly been performed in the prethrombolytic era. Despite the fact that modern management of AMI has reduced mortality rates, the occurrence of malignant ventricular arrhythmias in the late phase of AMI remains an important issue. We prospectively studied 244 consecutive patients (97 treated with thrombolytics) who survived a first AMI. All patients underwent time domain signal-averaged electrocardiography (vector magnitude: measurements of total QRS duration, terminal low [<40 microV] amplitude signal duration, and root-mean-square voltage of the last 40 ms of the QRS complex), Holter electrocardiographic monitoring, and cardiac catheterization. Late life-threatening ventricular arrhythmias were recorded. Eighteen arrhythmic events occurred during a mean follow-up period of 57 +/- 18 months. Three independent factors were associated with a higher risk of arrhythmic events: (1) left ventricular ejection fraction (odds ratio 1.9/0.10 decrease), (2) terminal low-amplitude signal duration (odds ratio 1.5/5 ms increase), and (3) absence of thrombolytic therapy (odds ratio 3.9). Low-amplitude signal duration sensitivity for sudden cardiac death was low (30%). Left ventricular ejection fraction had the highest positive predictive value for sudden cardiac death (10%). Thus, thrombolysis decreases both the incidence of ventricular tachycardia and sudden cardiac death with a higher reopening rate of the infarct-related vessel. Signal averaging predicts the occurrence of ventricular tachycardia and an impaired left ventricular ejection fraction predicts the occurrence of sudden cardiac death.

Arrhythmias, Cardiac↗

PubMed1997

Prognostic significance of myocardial ischemia detected by ambulatory electrocardiography, exercise treadmill testing, and electrocardiogram at rest to predict cardiac events by one year (the Asymptomatic Cardiac Ischemia Pilot [ACIP] study)

Myocardial ischemia identified by ambulatory electrocardiography (AECG), exercising treadmill testing, (ETT), or 12-lead electrocardiogram at rest is associated with an adverse prognosis, but the effect of improving these ischemic manifestations by treatment on outcome is unknown. The Asymptomatic Cardiac Ischemia Pilot (ACIP) study was a National Heart, Lung, and Blood Institute funded study to determine the feasibility of conducting a large-scale prognosis study and to assess the effect of 3 treatment strategies (angina-guided strategy, AECG ischemia-guided strategy, and revascularization strategy) in reducing the manifestations of ischemia as indicated by AECG and ETT. The study cohort for this database study consisted of 496 randomized patients who performed the AECG, ETT, and 12-lead electrocardiogram at rest at both the qualifying and week 12 visits. The effect of modifying ischemia by treatment on the incidence of cardiac events (death, myocardial infarction, coronary revascularization procedure, or hospitalization for an ischemic event) at 1 year was examined. In the 2 medical treatment groups (n = 328) there was an association between the number of ambulatory electrocardiographic ischemic episodes at the qualifying visit and combined cardiac events at 1 year (p = 0.003). In the AECG ischemia-guided patients there was a trend associating greater reduction in the number of ambulatory electrocardiographic ischemia episodes with a reduced incidence of combined cardiac events (r = -0.15, p = 0.06). In the revascularization strategy patients this association was absent. In the medical treatment patients the exercise duration on the baseline ETT was inversely associated with an adverse prognosis (p = 0.02). The medical treatment strategies only slightly improved the exercise time and the exercise duration remained of prognostic significance. In the revascularization group strategy patients this association was absent. Thus, myocardial ischemia detected by AECG and an abnormal ETT are each independently associated with an adverse cardiac outcome in patients subsequently treated medically.

Electrocardiography↗