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PubMed1980

[Possibilities for misinterpretation of direct fetal electrocardiography].

Direct foetal electrocardiography doses help the experienced examiner to detect cardiac arrhythmia. It can be an early signal of imminent danger. However, errors may occur to the interpreter of foetal electrocardiograms. They may be caused by materno-foetal ECG conduction in a case of intra-uterine foetal death, appearance of maternal pulses in the foetal curve, errors in pole connection of the scalp electrode, and superposition of alternating current on the ECG curve. Knowledge of those potential sources of error is essential, if erroneous decisions are to be avoided.

Arrhythmias, Cardiac↗

PubMed1978

Exercise electrocardiography in the evaluation of cardiac dysrhythmias in children.

Exercise electrocardiography is a useful means to evaluate dysrhythmias in children and young adults. Exercise may suppress a dysrhythmia present at rest and thus suggest a relatively benign problem. It may provoke a latent dysrhythmia which is absent at rest but suggested by a history of exercise intolerance or palpitation with exertion. Exercise may also modify a dysrhythmia. Maximum exercise testing has been used to evaluate each of these situations in children. The results of testing will be presented. Since no dysrhythmias were provoked in 170 healthy children, we think that any dysrhythmia initiated by exercise in the young should be considered abnormal.

Adolescent↗

PubMed1980

Limitations in equine fetal electrocardiography.

Technical and interpretive limitations of equine fetal electrocardiography were evaluated in recordings obtained from 45 pregnant mares. Technical limitations were related to the small amplitude of the fetal electrocardiogram and the variability in the lead configuration providing the best recording. It was found that recording the fetal electrocardiogram at high sensitivity and high base-line fidelity in several different leads was necessary to obtain satisfactory tracings. Interpretive limitations were related in part to the small amplitude of the fetal electrocardiogram and to the marked variability in heart rate between fetuses. The great variability in normal fetal heart rate makes a diagnosis of fetal tachycardia or distress unless serial tracings are available.

Animals↗

PubMed1995

The effects of noise and errors in heart size on numerical techniques for the inverse problem of electrocardiography.

In this study we examine the effects of both noise and geometrical errors on four numerical methods proposed for solving the inverse problem of electrocardiography. The heart-body system is modeled using an inhomogeneous eccentric sphere model. The cardiac source is modeled as a double layer spherical cap with either an anterior or posterior location. Epicardial potentials determined using the numerical techniques were compared with the analytically determin potentials in the presence of both noise and errors in assumed geometry.

Biomedical Engineering↗

PubMed1994

[Influence of gender and size on parameters measured by signal-averaged electrocardiography in healthy subjects: preliminary study].

The aim of this study was to determine the influence of electrocardiographic and biomorphometric factors on the parameters measured by signal averaged electrocardiography (SA-ECG) in normal subjects. The study population comprised 40 Caucasian students (20 men, 20 women). The SA-ECG measured 6 parameters: total duration of the averaged QRS, the root mean square of the voltage of the last 40 ms of the QRS (RMS 40) and the length duration of the terminal signal of under 40 microV (LAS), each parameter being measured with a band pass filter of 25 and 40 Hz. The echocardiographic recording included measurement of 12 parameters including left ventricular mass and ventricular volumes. Five morphological parameters were measured, including height, weight and body surface area. The duration of QRS measured with a 25 Hz band pass filter was significantly longer by 9.7 ms in men than in women (102.9 +/- 8.5 ms versus 93.2 +/- 8.1 ms; p < 0.001). Similarly, QRS duration measured with the 40 Hz band pass filter was longer in men by 11.4 ms than in women (102.1 +/- 9.6 ms versus 90.7 +/- 7.5 ms; p < 0.001). Multiple linear regression analyses showed that in both men and women, the duration of the QRS measured with either a 25 or 40 Hz band pass filter was correlated to size: the taller the subject, the longer the QRS duration. A negative correlation was observed between size and RMS 40 measured with both 25 and 40 Hz band pass filters: the taller the subject, the smaller the value of RMS 40.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

On-line computerized vectorcardiography monitoring of myocardial ischemia during coronary angioplasty: comparison with 12-lead electrocardiography.

BACKGROUND: With new interventions minimizing ischemic myocardial injury, accurate and reliable techniques for the detection and continuous monitoring of myocardial ischemia are essential. We compared two techniques used for the detection of myocardial ischemia during coronary angioplasty: on-line computerized vectorcardiographic (cVCG) monitoring and the standard electrocardiography (ECG) leads or the complete 12-lead ECG. METHODS: Thirty patients scheduled for routine angioplasty were included in the study. cVCG was recorded continuously. The electrodes were placed according to the lead system described by Frank and connected to a computerized system for on-line vectorcardiography. A 12-lead ECG was recorded simultaneously. The absolute variable spatial ST vector magnitude (ST-VM) and the relative variable spatial ST change vector magnitude (STC-VM) were calculated and compared with the standard 12-lead ECG for the detection of ischemia. RESULTS: The sum of deviation in ST segment in all 12 standard ECG leads correlated closely with STC-VM, irrespective of which artery was occluded. STC-VM indicated ischemia during the first balloon inflation in 87% of the patients and demonstrated ischemia in more patients than the standard 12-lead ECG. Myocardial ischemia was not demonstrated by ST-VM in five out of 26 patients with ischemia according to STC-VM. In these cases, mainly directional vector changes and fewer changes in magnitude were observed. CONCLUSION: Compared with 12-lead ECG, on-line cVCG is a more sensitive method of detecting myocardial ischemia during coronary angioplasty and the reading is easier and faster. Our results support STC-VM > or = 0.050 mV as the criterion for ischemia during angioplasty; ST-VM should be applied together with STC-VM.

Angina Pectoris↗

PubMed1994

[Long-term results of an independent study program of electrocardiography applied to medical students].

In medical education, programs that promote independent study are favored over traditional teaching methodologies. Aiming to assess the long term results of this pedagogic approach, fifth year medical students were assigned to receive self instruction modules or expositive lectures on electrocardiography. The knowledge and opinions of these two groups were evaluated two years later. Knowledge assessment was significantly better among students receiving self instruction modules (75.3 +/- 9.3 vs 65.4 +/- 12.9 points, in a scale ranging from 1 to 100 (p < 0.001). The self instruction method and traditional lectures were qualified as very useful by 86.8 and 38.9% of students respectively. It is concluded that self instruction methods have good long term results, when applied to medical students.

Case-Control Studies↗

PubMed1975

[Radiotelemetric electrocardiography for the detection of "paroxysmal tachycardia" under the influence of various stresses].

Modern longterm electrocardiography (telemetry, tape recorder) permits the simultaneous recording of heart rate and arrhythmias and analysis of the QRS complex and ST-T sections. "Paroxysmal tachycardia" in different stress situations and the telemetric electrocardiograph tracing must be interpreted taking into consideration additional findings of clinical cardiological examinations. Of 82 subjects, 30 with the symptom "tachycardia" with familial and/or occupational stress could be subdivided into three disease groups: Group A: autonomic lability of healthy hearts; Group B: patients with pre-excitation syndrome; Group C: organic heart disease patients.

Adult↗

PubMed1994

Simultaneous electrocardiography and Doppler echocardiography in pulsus alternans.

Pulsus alternans, the alternating strong and week pulses which occur in patients with severe heart failure, was first described by Traube in 1872. Since then various methods, both invasive1,2 and non-invasive3,4, have been used to study this phenomenon. This study demonstrates the utility of using simultaneous electrocardiography (ECG) and Doppler echocardiography to document pulsus alternans, and to differentiate it from other causes of alternating pulses.

Echocardiography, Doppler↗

PubMed1994

Preoperative screening electrocardiography: predictive value for postoperative cardiac complications.

The purpose of this study was to evaluate the value of preoperative electrocardiography in predicting postoperative cardiac complications. Four hundred eighty-one patients having elective surgery were eligible. The patients' ages and specific ECG findings were recorded preoperatively. The patients had prospective follow-up from admission to discharge for the development of postoperative cardiac complications. The data were analyzed using stepwise logistic regression. Postoperative ischemic events were predicted by ECG findings of ST segment abnormalities and ECG evidence of previous myocardial infarction. Age, P wave abnormalities, and preoperative dysrhythmias were independent predictors of postoperative dysrhythmic events. These specific ECG findings may identify patients at risk of postoperative ischemia or dysrhythmia. These patients may benefit from aggressive preoperative cardiac evaluation or close postoperative cardiac monitoring.

Adult↗

PubMed1993

Effects of angiotensin-converting enzyme inhibitor therapy on presence of late potentials detected using signal-averaged electrocardiography in patients with congestive heart failure.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitors have been shown to improve the mortality rate in patients with congestive heart failure. The exact mechanism of this effect is uncertain. Signal-averaged electrocardiography has been used to evaluate the presence of late potentials as a marker for sudden cardiac death. We examined prospectively the effects of ACE inhibitor therapy on signal-averaged ECGs and ventricular arrhythmia frequency in 20 patients with moderate to severe left ventricular dysfunction and symptomatic congestive heart failure. METHODS: A signal-averaged ECG and 24 h Holter monitor were performed immediately before and both 1 week and 6 weeks after captopril initiation. The mean dose of captopril at 6 weeks was 38 +/- 31 mg. The patients (19 men and one woman, mean age 63 +/- 12 years) had a baseline ejection fraction of 22 +/- 7% and mean functional class of 2.6 +/- 0.5. The cause of congestive heart failure was coronary artery disease in 18 patients, idiopathic cardiomyopathy in one, and valvular disease in one. RESULTS: All three signal-averaged ECG time-domain parameters tended to improve over the course of the study (study 1, 2, 3: QRS duration (ms) = 108 +/- 11, 106 +/- 12, 105 +/- 11; low-amplitude signal duration (ms) = 30 +/- 8, 31 +/- 10, 28 +/- 10; root mean voltage (microV) = 33 +/- 20, 37 +/- 24, 40 +/- 2, respectively). These changes were not statistically significant, although the improvement in QRS duration was nearly so with P = 0.06. The occurrence and complexity of ventricular ectopy did not appear to be consistently altered. CONCLUSION: ACE inhibitor therapy with captopril did not appear to alter ventricular ectopy over the course of this study. However, the trends toward improvement of signal-averaged ECG parameters deserve further evaluation in a larger and longer-term study.

Action Potentials↗

PubMed1994

Clinical applications of signal-averaged electrocardiography in patients after myocardial infarction.

In conclusion, signal-averaged electrocardiography is a useful, noninvasive technique to identify patients after myocardial infarction at risk for future arrhythmic events, especially in conjunction to existing tools, such as 24 hour ambulatory monitoring, echocardiography, nucleotide angiography and coronary angiography. It has a limited positive predictive value, but has an excellent negative predictive value. The optimum time to do signal-averaged electrocardiograms after myocardial infarction is unclear, 6 to 14 days after myocardial infarction has the highest sensitivity. Time domain analysis remains the most common method used to record late potentials. The definition of late potential and the scoring of a high resolution electrocardiogram as normal and abnormal have not yet been resolved. The criteria proposed by the Task Force Committee of the European Society of Cardiology, the American Heart Association and the American College of Cardiology (see introduction) should be observed at present. Many studies on signal-averaging were done in the prethrombolytic era. In patients who have received thrombolytic therapy, the positive predictive value of signal-averaged electrocardiograms has decreased. There are other limitations in applying signal averaging technique. The faster the ventricular tachycardia is induced in electrophysiological studies, the shorter is the late potential. Thus, a faster tachycardia which causes sudden cardiac death may not be detected by late potentials. The management strategies for patients who have abnormal signal-averaged electrocardiograms after myocardial infarction have not be defined. One should note that any management strategy has to prove that it improves prognosis. More prospective, randomized clinical trials are required to address these issues.

Arrhythmias, Cardiac↗

PubMedDate not supplied

[Medical gels for ultrasonographic diagnosis, therapy and electrocardiography].

The All-Russian Research Institute of Medical Polymers has designed the medical gels REPAC, DIAGEL, for ultrasound diagnosis, REPAC-T for ultrasound therapy, ELCON and ELCARD for electrocardiography. REPAC, DIAGEL, and REPAC-T have the least sound damping factor (approximately 10(-3) dB/cm) as compared to other similar gels. REPAC and DIAGEL showed a good performance when they were applied in clinical practice during a year. REPAC-T is the gel that can be used both for ultrasound studies and for ultrasound therapy. Unlike REPAC, it has a longer drying-out time, ensuring a 100% contact between the patient's body and the transducer up to 20 minutes. Other gels have been designed for long-term ECG monitoring, bicycle ergometry, etc. ELCARD and ELCON have conductivities of 0.4-0.6 and 0.6-0.9 ohm/m, respectively.

Electrocardiography↗

PubMedDate not supplied

Signal-averaged electrocardiography in survivors of first acute myocardial infarction: a pre-hospital discharge study.

Ninety one consecutive survivors of a first acute myocardial infarction (MI) were studied prior to hospital discharge, in order to observe the relationship of signal-averaged electrocardiography (SAECG) to thrombolytic therapy, site of infarction and left ventricular function. Sixty six patients received thrombolytic agents and the remaining had conventional therapy. The overall incidence of abnormal SAECG was 27 percent and 16 percent with high-pass 40 Hz and 25 Hz filters respectively. The SAECG (40Hz) was abnormal in 12 of 25 patients (48%) who did not receive thrombolytic therapy and in 13 of 66 (20%) who were thrombolysed (p < 0.01). When patients were classified according to the site of myocardial infarction, 6 out of 10 patients (60%) with anterior MI who were not thrombolysed had abnormal SAECG as compared to 10 of 51(20%) who received this treatment (p < 0.01), with no significant difference among inferior myocardial infarction patients. The mean (+/- SEM) ejection fraction (EF%) of anterior myocardial infarction patients was 31 +/- 3 percent in those with abnormal SAECG when compared to 39 +/- 2 percent in patients with normal SAECG (p < 0.05). Similarly, in patients with inferior myocardial infarction, the mean EF among these respective groups was 41 +/- 2 and 47 +/- 2 percent (p < 0.05). The mean echocardiographic score, which reflected regional LV wall motion abnormality, was not different between patients with anterior infarction when the groups with abnormal and normal SAECG were compared (9.1 +/- 0.6 versus 6.4 +/- 0.4), but differed significantly between inferior infarction patients (5.8 +/- 0.7 versus 4.6 +/- 0.4 respectively; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1996

[High-resolution electrocardiography in monitoring myocardial damage after therapy with anthracyclines in children].

BACKGROUND: Anthracycline cytostatics, widely used in oncologic practice, may induce discrete myocardial damage occasionally culminating in life-threatening cardiologic complications. The most serious clinical manifestations of anthracycline cardiotoxicity are dilated cardiomyopathy, heart failure and fatal arrhythmias. OBJECTIVES, STARTING POINT AND MAIN PURPOSE: High-resolution electrocardiography (HRECG) is one of the latest cardiologic methods, which can be promising for early identification of patients at risk of anthracycline cardiotoxicity. The aim of this study is the evaluation of the incidence of HRECG abnormalities in a group of paediatric patients treated with anthracyclines and the usefulness of HRECG for stratification of patients at risk of the clinical cardiotoxicity. PATIENTS AND METHODS: A set of 60 oncologic paediatric patients treated with anthracyclines was divided into two groups. The first group was formed by 15 patients undergoing evaluation during their anthracycline therapy (median after the last administration of antracyclines was 3.2 days). Their average age at the time of examination was 14.7 +/- 4.1 years. The total cumulative dose of antracyclines was 40-300 mg/m2 (median 150 mg/m2). The second group was formed by 45 patients who were evaluated after completing anthracycline therapy. The interval of time from the last administration of antracycline in this subgroup of patients was 3 months-12 years (median 5.5 years). Their average age at the time of HRECG examination was 14 +/- 4.1 years. The total cumulative dose of anthracyclines was 90-440 mg/m2 (median 230 mg/m2). Six patients of this group (13.3%) were treated also with mediastinal radiotherapy (18-40 Gy). 43 patients (95.5%) of second group were in complete remission, two other patients yielded a progression of their malignancy. 10 patients (22%) were examined by HRECG 2-5 times in app. two-month intervals. The control group was formed by 30 randomly selected healthy children and adolescents with normal ECG. Average age was 15.1 +/- 5.8 years. Using HRECG the time- and frequency-domain characteristics of the ECG signal were analyzed. The time-domain analysis was performed at 40-250 Hz filter. The frequency-domain analysis was performed by fast Fourier transformation (FFT), a 120 ms segment starting 20 ms before the end of the QRS complex was analyzed. The altered frequency content was expressed as the ratio of frequency areas (area ratio, AR) 20-50 Hz/0-20Hz. The average level of noise was 0.56 microV in the first group, 0.62 microV in the second group of patients and 0.68 microV in the control group. RESULTS: Abnormalities in the time-domain analysis (ventricular late potentials, VLP) were present in 2 (13.3%) of 15 patients during the anthracycline therapy in the first group and in 4 (8.8%) of 45 patients after completing therapy in the second group. No abnormalities in the time-domain analysis were detected in the control group. Using frequency-domain analysis, abnormalities in AR20-50 Hz/0-20 Hz were found in 8 (53.3%) of 15 patients of the first group, and in 11 (24.4%) of 45 patients of the second group. Significant differences were observed in the frequency parameters of the ECG signal in patients of the first group in comparison to the control group (p = 0.0018) and also when comparing the patients of the second group and the control group (p = 0.045). CONCLUSION: The HRECG results in time- and frequency-domain analyses indicate to high incidence of HRECG abnormalities in patients examined both during and after the antracycline therapy in comparison to the control group. The prognostic use of the HRECG abnormalities must be established in a larger and longer study. (Fig. 4, Tab. 2, Ref. 43.)

Adolescent↗

PubMedDate not supplied

Acute cardiotoxicity of moniliformin in broiler chickens as measured by electrocardiography.

Electrocardiography was used to examine the acute cardiotoxic effects of moniliformin on 3-week-old broiler chickens. Each of the seven pairs of anesthetized birds (pentobarbital sodium, 40 mg/kg body weight, intramuscular) was injected intravenously with moniliformin (1 mg/kg body weight) or an equal volume of normal saline (1 ml/kg body weight), and changes in electrocardiogram were monitored for 50 minutes. Three of the seven birds injected with moniliformin died within 50 minutes post-injection. Moniliformin caused a bradycardia, which became highly significant (P < 0.05) within 15 minutes post-injection. The P-R, Q-T, and S-T intervals of moniliformin-injected birds were significantly lengthened throughout the 50-minute observation (P < 0.05). The results indicate that the moniliformin-induced mortality is due primarily to cardiac failure.

Animals↗

PubMed1996

[Accurate placement of central venous catheters using right atrial electrocardiography].

We have evaluated the effectiveness of central venous catheter placement using right atrial electrocardiography (RAECG). Consecutive patients under general anesthesia (n = 42) who required a central venous catheter underwent RAECG-guided catheter insertion procedure via right internal jugular vein. Catheter tip position was verified by post procedure portable chest radiography. Forty of 42 catheter tips were placed above the superior vena cava-right atrial junction, and none of them had its associated complications. The average insertion depth of catheters was 16.4 cm. We also attempted to predict the optimal catheter insertion depth for each patient from the previous measurements of external landmarks, but it was found to be difficult to predict reliably. In this point of view, we should use RAECG technique to make sure the proper positioning of the catheter tip.

Aged↗

PubMed1997

[Simultaneous ambulatory electrocardiography and pulse oximetry].

We developed a system for 24-hour ambulatory recording of blood oxygenation (SpO2) and electrocardiography (ECG). Using this system, we studied 10 healthy volunteers and 7 patients with chronic pulmonary diseases. The system incorporated a portable pulse oximeter (SM50) manufactured by Fukuda Denshi KK; the first and second channels were used to record ECG data and the third was used to record SpO2 data. An SpO2 sensor (Dispo-sensor D-25; Nellcor Inc.) was applied to the fourth of fifth finger. The SpO2 data (MicrO2; Siemens AG) were digitized and stored in the ambulatory recording device; the ECG was recorded simultaneously. The data were analyzed with a model DMW-9000H analyzer (Fukuda Denshi KK). A custom-designed program was also used, to remove noise errors. In the healty volunteers, SpO2 was at least 90% for the entire 24 hours. In all the patients, SpO2 fell below 90% at rest during the night or after a 15-minute walk. Transient atrial tachycardia was observed in 3 patients, and during the tachycardia the SpO2 was low. The number of extra ventricular beats divided by the total number of beats increased more in the patients than in the healthy volunteers (1.21 +/- 0.89 vs 0.6 +/- 0.3%, p < 0.05). SpO2 did not change significantly in the patients. In outpatients and in patients receiving home health care, the present system facilitates simultaneous diagnosis of respiratory failure an arrhythmias. In patients with chronic pulmonary diseases desaturation may cause transient atrial tachycardia.

Adult↗