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PubMed1991

QTc prolongation measured by standard 12-lead electrocardiography is an independent risk factor for sudden death due to cardiac arrest.

BACKGROUND: QTc prolongation has been implicated as a risk factor for sudden death; however, a controversy exists over its significance. METHODS AND RESULTS: In the Rotterdam QT Project, 6,693 consecutive patients who underwent 24-hour ambulatory electrocardiography were followed up for 2 years; of these, 245 patients died suddenly. A standard 12-lead electrocardiogram and clinical data at the time of 24-hour ambulatory electrocardiography were collected for all patients who died suddenly and for a random sample of 467 patients from the study cohort. In all patients without an intraventricular conduction defect (176 patients who died suddenly and 390 patients from the sample), QT interval duration was measured in leads I, II, and III and corrected for heart rate with Bazett's formula (QTc). In patients without evidence of cardiac dysfunction (history of symptoms of pump failure or an ejection fraction less than 40%), QTc of more than 440 msec was associated with a 2.3 times higher risk for sudden death compared with a QTc of 440 msec or less (95% confidence interval: 1.4, 3.9). In contrast, in patients with evidence of cardiac dysfunction, the relative risk of QTc prolongation was 1.0 (0.5, 1.9). Adjustment for age, gender, history of myocardial infarction, heart rate, and the use of drugs did not alter these relative risks. CONCLUSIONS: These data indicate that in patients without intraventricular conduction defects and cardiac dysfunction, QTc prolongation measured from the standard electrocardiogram is a risk factor for sudden death independent of age, history of myocardial infarction, heart rate, and drug use. In patients with cardiac dysfunction, QTc duration is not related to the risk for sudden death.

Death, Sudden↗

PubMed1990

Open access exercise electrocardiography: does it improve the management of cardiovascular disease in the community?

In this study the use of exercise electrocardiography, by 47 general practitioners in South East Kent has been evaluated. Of 110 consecutive requests the majority (88%) were for diagnostic purposes, while only 7% were for prognostic assessment. Many of those referred were young or had non-cardiac chest pain and in 59% of cases the test result was unlikely to alter the clinical assessment of the probability of ischaemic heart disease (IHD). The test result influenced patient management in 85% of cases. Only 15% of patients were subsequently referred to the district general hospital although all had been considered for referral prior to the test. Although referral for invasive investigation of six patients was expedited by the provision of stress testing, in five patients general practitioners failed to consider any further investigation despite the patient having a strongly positive test. General practitioners use exercise electrocardiography primarily to exclude IHD in patients at low risk and provide reassurance. They rarely use the test as a means to guide management of those with known or probable IHD.

Cardiovascular Diseases↗

PubMed1999

Can single-lead computerized electrocardiography predict myocardial infarction in young and middle-aged men? The Tromsø study.

BACKGROUND: In epidemiological studies, the electrocardiogram has often been interpreted by means of a categorical classification. Computerized recording offers the possibility of analysing electrocardiographic measurements as continuous variables. OBJECTIVE: To test the hypothesis that duration of QRS complex and T-wave inversion would be independent predictors of myocardial infarction. METHODS: In a population-based study, we prospectively investigated the risk of developing myocardial infarction according to duration of ORS complex and peak-to-peak T-wave amplitude measured from lead I of the 12-lead electrocardiogram by computerized electrocardiography. In total 6628 men aged 25-61 years who had not previously suffered a myocardial infarction were followed up for 3.9 years. RESULTS: Eighty-two first myocardial infarctions (55 non-fatal and 24 fatal myocardial infarctions and three sudden deaths) were identified. The risk of myocardial infarction increased with duration of ORS complex and with decreasing T-wave amplitude. A proportional hazards model with adjustment for possible confounders yielded a relative risk of myocardial infarction of 3.74 (P for linear trend 0.015) for duration of QRS complex > or = 120 ms compared with duration of QRS complex <80 ms. The multivariate relative risk for T-wave amplitude > or = 0.35 mV compared with T-wave amplitude < 0.20 mV was 0.55 (P for linear trend 0.036). When both duration of ORS complex and T-wave amplitude were included in the multivariate model, T-wave amplitude retained its predictive power, whereas duration of ORS complex became marginally no longer significant (P=0.067). CONCLUSIONS: Peak-to-peak T-wave amplitude from lead I is an independent predictor of myocardial infarction in men who have not previously suffered a myocardial infarction. Greater duration of ORS complex clearly indicates a higher risk of myocardial infarction. However, when T-wave amplitude is included as a covariate, the predictive power of duration of QRS complex does not remain significant. Single-lead electrocardiography is a feasible method for improving the assessment of the relative risk of myocardial infarction.

Adult↗

PubMed2004

Accurate central venous port-A catheter placement: intravenous electrocardiography and surface landmark techniques compared by using transesophageal echocardiography.

UNLABELLED: Using transesophageal echocardiography (TEE) to locate the tip of central venous catheters inserted via the right subclavian vein, we compared IV electrocardiography (IV-ECG)-guided catheter tip placement with the conventional surface landmark technique. Sixty patients were randomly assigned into two groups. In Group E, the IV-ECG signal was conducted along an NaHCO(3)-filled catheter to facilitate catheter placement. In Group S, surface landmarks on the chest wall were used to determine the appropriate catheter length. The goal was to visualize the catheter tip with TEE at the superior edge of the crista terminalis, which is the junction of the superior vena cava (SVC) and right atrium (RA). The catheter tip position was considered to be satisfactory, as the tip was within 1.0 cm of the upper crista terminalis edge. All 30 Group E patients had satisfactory catheter tip placement when the ECG P wave was at its maximum. In contrast, 16 of the 30 patients in Group S had satisfactory tip positions (P < 0.001). All catheters were repositioned under TEE guidance to adjust the tip to the SVC-RA junction. After the catheter tips were confirmed to be located at the SVC-RA junction, the catheter tips were still visualized in the mid portion of RA in 12 of 60 patients on supine chest radiographs. We concluded that IV-ECG guidance to position a catheter resulted in satisfactory catheter tip placement that is in accordance with TEE views. Catheter placement at the SVC-RA junction with the surface landmark technique was unreliable. IMPLICATIONS: Intravenous electrocardiography guidance to position catheters obtains a satisfactory catheter tip placement that is in accordance with transesophageal echocardiography views. The surface landmark technique does not result in reliable placement at the superior vena cava-right atrium junction.

Aged↗

PubMed1985

Usefulness of long-term ambulatory electrocardiography in heart disease screening system for school children and high school students.

Long-term ambulatory electrocardiography was utilized in a heart disease screening system for elementary school children and junior and senior high school students in Nagoya, Japan. The elementary school children, and junior and senior high school students who have serious arrhythmias or potential risk of syncope and sudden death are the subjects of ambulatory monitoring. Of 42 school children and students taking ambulatory electrocardiography for frequent ventricular premature contractions, 8 had Lown's grade 4A, 4B or 5. The cases with third-degree AV block showed ventricular tachycardia or frequent ventricular premature contractions during exercise in ambulatory electrocardiograms. These complex ventricular arrhythmias are possible risk factors of sudden death. It has been proved that ambulatory monitoring is beneficial in the screening and management of serious arrhythmias in the heart disease screening system.

Adolescent↗

PubMed2005

Centenary of tele-electrocardiography and telephonocardiography.

In the history of electrocardiography the names of two physiologists stand out: Augustus Waller (1865-1922) and Willem Einthoven (1860-1927). Waller was the first to show that the beating heart produces a weak electric potential, which can be registered by a measuring device connected to electrodes attached to the skin. Einthoven developed a 'string' galvanometer, which was much faster and more sensitive than the system used by Waller. Einthoven's electrocardiograph was ready for use in 1903. To facilitate investigations of patients Einthoven connected his instrument to the Academic Hospital in Leyden, by a telephone line, as suggested by his engineering colleague Johannes Bosscha in Delft. The first successful tele-electrocardiogram was transmitted on Sunday 22 March 1905. The heart tones were registered by wiring a specially developed microphone placed on the subject's chest to another string galvanometer. The event was therefore a first both for tele-electrocardiography and for telephonocardiography. We are still awaiting the full-scale implementation of these achievements, 100 years later.

Electrocardiography↗

PubMed1991

Relation between the incidence of arrhythmias and ischemic ST-segment depression during dipyridamole electrocardiography test in patients with coronary artery disease.

To examine the incidence of arrhythmias in dipyridamole infusion and the relation between dipyridamole-induced arrhythmias and ST-segment depression, dipyridamole electrocardiography tests were performed on 100 patients with coronary artery disease. Dipyridamole was infused at a rate of 0.568 mg/kg for 4 min, and 87-lead body surface mapping was performed to determine ischemic ST-segment depression. Positive ischemic response was defined as greater than or equal to 0.10 mV horizontal or downsloping ST-segment depression below the baseline, lasting 80 msec after the J point. Arrhythmias were observed by continuous electrocardiographic monitoring using a CM-5 lead electrocardiography. With respect to ventricular premature contractions (VPC), a group of patients with previous myocardial infarction (MI group) had a significantly higher incidence than a group of patients without previous myocardial infarction (non-MI group) before (16.7% vs. 1.7%, p less than 0.01) and after (38.1% vs. 3.4%, p less than 0.005) the dipyridamole infusion. The incidence of supraventricular premature contractions (SVPC), however, was not significantly different between the MI and non-MI groups. A group of patients with positive ischemic response had a significantly higher incidence of SVPC after the dipyridamole infusion than a group of patients with negative ischemic response (p less than 0.005). However, there was no significant difference in the incidence of VPC between the negative and positive ischemic response groups. These results suggest that dipyridamole-induced VPC is not always associated with ischemic ST-segment depression, but dipyridamole-induced SVPC is associated with dipyridamole-induced ischemic ST-segment depression in patients with coronary artery disease.

Adult↗

PubMed2000

Results of ambulatory electrocardiography in overtly healthy Doberman Pinschers with echocardiographic abnormalities.

OBJECTIVE: To identify, by means of 24-hour ambulatory electrocardiography, electrocardiographic abnormalities in overtly healthy Doberman Pinschers in which results of echocardiography were abnormal. DESIGN: Clinical case series. ANIMALS: 56 (35 male, 21 female) overtly healthy Doberman Pinschers with echocardiographic evidence of cardiomyopathy on initial examination that subsequently died of cardiomyopathy. PROCEDURE: Twenty-four-hour ambulatory electrocardiographic (Holter) recordings obtained at the time of initial examination were reviewed. For all dogs, scan quality was > 90%. RESULTS: Initial Holter recordings of all 56 dogs contained ventricular premature contractions (VPC). Thirty-six (65%) dogs had > 1,000 VPC/24 h, 17 (31%) had > 5,000 VPC/24 h, and 11 (19%) had > 10,000 VPC/24 h. Fifty-four (96%) dogs had couplets of VPC, 37 (66%) had triplets of VPC, and 36 (64%) had episodes of nonsustained (< 30 seconds) ventricular tachycardia. Number of VPC/24 h during the initial Holter recordings was positively correlated with numbers of couplets and triplets of VPC and number of ventricular escape beats and negatively correlated with left ventricular fractional shortening. Twenty-eight dogs died suddenly prior to the putative onset of congestive heart failure. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that along with echocardiography, 24-hour ambulatory electrocardiography can be used to help identify overtly healthy Doberman Pinschers with cardiomyopathy.

Animals↗

PubMed2001

Results of ambulatory electrocardiography in overtly healthy Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy.

OBJECTIVE: To determine results of ambulatory electrocardiography in and outcome of overtly healthy Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy. DESIGN: Case series. ANIMALS: 44 overtly healthy (25 male, 19 female) Doberman Pinschers. PROCEDURE: 24-hour ambulatory electrocardiographic (Holter) recordings with > 90% scan quality obtained the same day that echocardiography was performed were reviewed. RESULTS: Holter recordings from 42 of 44 (95%) dogs contained ventricular premature complexes (VPC). Fifteen of 44 (34%) dogs had > 100 VPC, 9 (20%) had > 500 VPC, and 5 (11%) had > 1,000 VPC. Nonsustained (< 30 seconds) ventricular tachycardia was detected in 4 dogs. Eighteen of 27 (67%) dogs with > 100 VPC, any couplets or triplets of VPC, or ventricular tachycardia developed dilated cardiomyopathy within 1 year, compared with 8 of 17 (47%) dogs with < 100 VPC, no couplets or triplets of VPC, and no ventricular tachycardia. Of the 18 dogs that did not develop dilated cardiomyopathy within 1 year, 11 (61%) did so within 3 years. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a high percentage of Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy will be found to have VPC during 24-hour ambulatory electrocardiography and that most will develop echocardiographic abnormalities indicative of cardiomyopathy.

Animals↗

PubMed2002

Comparison of the prevalence of ventricular and supraventricular premature beats with 24-hour Holter electrocardiography between hypertensive and normotensive shift workers in a manufacturing company.

We conducted 24-hour Holter electrocardiography (ECG) among shift workers to assess whether there were differences in the prevalence of ventricular apd supraventricular premature beats between hypertensive (HT) and normotensive (NT) workers. Among the selected 24 male shift workers, 20 were fitted with 24-hour Holter ECG monitors. Nine workers were in the HT group and 11 the NT group. The prevalence of isolated supraventricular premature beats (SVPBs) and SVPB runs were higher in the HT group than in the NT group, but without statistical significance. The prevalence of ventricular premature beats (VPBs) was similar between groups. One worker in each group experienced > or = 720 VPBs per 24 hours, while the worker in the HT group was detected as having a short run of VPBs. The results suggested the necessity of a larger scale study to clarify an association between hypertension and arrhythmias using 24-hour Holter electrocardiography.

Adult↗

PubMedDate not supplied

Signal-averaged electrocardiography for detection of ventricular tachycardia using fast Fourier transform filtering on a standard ECG cart.

Signal-averaged electrocardiography has been advocated as a technique to predict the occurrence of ventricular tachycardia, especially in patients with ischemic heart disease. We studied a heterogeneous population of 77 patients referred for electrophysiologic testing using a recently developed fast Fourier transform filtering system available as part of a standard electrocardiography cart. The sensitivity, specificity, and positive predictive accuracy of this system were consistent with those previously determined using bidirectional Butterworth filters or finite impulse response filtering techniques. This new filtering approach in generation of signal-averaged ECG data for detection of ventricular tachycardia has promise but will require use in larger groups to establish its true clinical value.

Electrocardiography↗

PubMed1977

Ambulatory electrocardiography. A clinical perspective.

Advances in modern technology have made it possible to record and analyze the electrocardiographic data of ambulatory persons for as many as 24 h or more. This capability and an increasing awareness of cardiac dysrhythmias and myocardial ischemia as a cause of morbidity and mortality have led to the more widespread use of ambulatory electrocardiography in the examination of patients for various clinical conditions. From a clinical viewpoint, we review and summarize the present state-of-the-art of ambulatory electrocardiography and discuss when such studies are indicated, frequently warranted, or may be useful.

Aged↗

PubMedDate not supplied

[Electrocardiography and echocardiography in the diagnosis of chronic cor pulmonale].

The study was aimed at evaluating the possibilities of electrocardiography (ECG) and echocardiography in establishing the diagnosis of chronic pulmonary heart disease (CPHD). Sixty patients with a chronic obstructive pulmonary disease (COPD) and clinical symptoms of cardiac decompensation were observed. The examined patients ranged from 26 to 74 years of age, the mean age being 59.25 years. The diagnosis of CPHD was established by electrocardiography in 43 patients (78.18%) while in 57 patients (95%) it was done by ultrasound cardiography. Morphologic changes of the right ventricle (RV) were quantified, i.e. the diagnosis of chronic pulmonary heart disease was confirmed by echocardiography parameters such as right ventricle free wall thickness--RVFWT (0.82 +/- 0.09 cm), enddiastolic right ventricle dimension--ERVD (3.78 +/- 0.73 cm) and tricuspid regurgitation--TR (2.9 +/- 0.59, i.e. 2.58 +/- 0.55 after therapy). The information on the right ventricle function was provided by the values of echocardiography parameters, right ventricle ejection fraction--RVEF (30.98 +/- 5.88%, i.e. 34.1 +/- 5.64 after therapy) and right ventricle systolic pressure--RVSP (60.41 +/- 16.98 mmHG, i.e. 51.50 +/- 12.76 after therapy). Monitoring of these values after therapy, as well as of the RTO changes gave a good insight into the therapy effects. Echocardiography has been concluded to be of better sensitivity than ECG in diagnosing CPHD and both methods, noninvasive and easily applicable, have an important role in examining cardiac changes in patients with COPD.

Adult↗

PubMed1992

Guidelines for judicious use of electrocardiography. A summary of recommendations from the ACC/AHA Task Force Report.

Electrocardiography continues to be a cornerstone in the management of an array of cardiac and noncardiac disorders. However, the ease with which an electrocardiogram can be obtained, as well as its low cost, has led to widespread use--and possible overuse--of this technology. A joint committee of the American College of Cardiology and the American Heart Association recently published guidelines for appropriate use of electrocardiography in patients with known heart disease; in persons suspected of having, or who are at risk for, heart disease; and in persons with no apparent or suspected cardiac disease. These guidelines can help clinicians determine when, and for which patients in the intensive care unit, an electrocardiogram is warranted.

American Heart Association↗

PubMed1993

Standard interchange for computerized electrocardiography.

In the SCP-ECG project (AIM #1015) of the pilot AIM Programme a standard communications protocol was developed for computerized electrocardiography, consisting of standards for the interchange, encoding and storage of digital ECG data. Part of this work is continued under the main AIM Programme (January 1992- December 1994) as AIM Project #2026, entitled "Open European Data Interchange and Processing for Computerized Electrocardiography (OEDIPE)" and was taken up by the CEN/TC 251 Committee as a priority item, for implementation into an official European Standard in Health Care Informatics. The objectives and implementation of this Standard are described in the present paper.

Electrocardiography↗

PubMed1999

The expanding role of signal-averaged electrocardiography.

Signal-averaged electrocardiography is a valuable diagnostic tool for determining which patients recovering from myocardial infarction are at risk of sudden death due to ventricular arrhythmias. Additionally, the value of this technique in determining which patients with ischemic heart disease and unexplained syncope are likely to have inducible sustained ventricular tachycardia has been established. This noninvasive screening procedure has shown promise in other clinical situations, but more investigation is needed before definitive recommendation can be made. Critical care nurses can help promote the success of signal-averaged electrocardiography by educating patients, promoting acquisition of a quality recording, helping allay patients' concerns, and participating in research activities.

Coronary Disease↗

PubMed2001

Echocardiography and exercise electrocardiography in the assessment of long-term outcome after percutaneous mitral valvuloplasty.

Before and immediate (invasive examination) and long-term follow-up (4.5 year; echocardiography, exercise electrocardiography) studies after percutaneous transvenous mitral valvuloplasty (PTMV; Inoue technique) were prospectively performed in 123 consecutive patients with pure or dominant mitral stenosis. These patients consisted of two groups: Group A with suitable valve morphology (n = 108, mean age 49.6 years, echocardiographic score 8.2 +/- 1.5), and Group B with less favourable valve morphology (n = 15, mean age 59.3 years, echocardiographic score 11.3 +/- 2.3) rejected for surgery because of high surgical risk. PTMV is a safe and effective nonsurgical method of treatment for symptomatic mitral stenosis and has long-lasting results in patients with pliable mitral valve as well as in patients with less suitable valve morphology. Echocardiography (Doppler approach) is the most efficient noninvasive method for assessment of PTMV effect. Exercise electrocardiography test is a valuable complementary method for objective measurement of patient working capacity and to confirm the success of PTMV.

Adult↗

PubMed1999

[A historical review of the study of electrical activity of heart and origination of electrocardiography].

This paper has an overall review of the historical process of electrocardiographic development and the origination of modern electrocardiography in retrospect and also has an analysis of the scientific background, the important events and the historical effect of outstanding figures throughout the development. The experience and laws contained in the historical development are briefly summerized in this paper. At the same time the authors point out that the establishment of modern electrocardiography and the related technical development are crystallization of the wisdom and the result of the hard work of many scientists including the figures who should have been awarded Nobel Prizes.

Biophysics↗