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PubMed1990

[Preoperative risk assessment: long-term electrocardiography for directed diagnosis of arrhythmias].

The role of ambulatory electrocardiography for detection, confirmation, or exclusion of severe forms of arrhythmias was investigated in our preoperative anesthesia clinic. In a prospective study over a period of 21 months, 30 of 8935 preoperatively evaluated patients (0.3%) scheduled for noncardiac surgery were monitored by 24-h ambulatory ECG. Indications included common clinical reasons for ordering an ambulatory ECG and additional specific "anesthesiologic" indications: Syncopes, dizziness, or other manifestations possibly related to cardiac arrhythmias; Rhythm disturbances under antiarrhythmic drug therapy; Suspected paroxysms of supraventricular tachycardia; Q-T syndrome, R- on-T phenomenon; Insignificant rhythm disturbances in patients with significant cardiac disease such as cardiomyopathy, aortic stenosis, mitral valve prolapse; Rhythm disturbances in patients with poor general medical status; Recent myocarditis with arrhythmias; Previous known or suspected intraoperative cardiac complications; Suspected sick sinus syndrome. The mean age of the patients was 63.9 years; most (24/30) were classified as ASA III. In 4 patients with suspected bradycardic rhythm disturbances the ambulatory ECG proved a useful method for further decision-making compared to the routine resting ECG. According to the long-term ECG recordings 22 patients were classified as Lown IV. After effective antiarrhythmic therapy--usually with propafenon--none of these patients (n = 13) or those classified as Lown 0 to III (n = 8) showed intraoperative arrhythmias or other hemodynamic problems. In contrast, of the patients with complex rhythm disturbances refractory to antiarrhythmic drug therapy (n = 4) or those in whom emergency operations were performed without antiarrhythmic drug therapy (n = 2), 4 developed severe arrhythmias or other intraoperative hemodynamic problems. Two died on the 1st postoperative day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

[What is the value of high resolution electrocardiography in the identification of patients at risk?].

Sudden cardiac death occurs in the Federal Republic of Germany with an incidence of 60,000 to 90,000 per year. Ambulatory ECG monitoring has demonstrated that in about 80% of such events, the heart rhythm before and during sudden cardiac death shows ventricular tachycardia leading to ventricular fibrillation and circulatory standstill. From experimental studies it is known that the substrate for precipitation of the ventricular arrhythmia is localized injury in myocardial tissue with conduction delays and conduction blocks resulting in inhomogeneous spread of the impulse between normal and injured myocardium enabling the existence of an electrical re-entry circuit. Anisotrophy, that is differing velocities of conduction parallel and perpendicular to fiber direction as well as dispersion of repolarization appears responsible for propagation of the circuit. Because of the delayed impulse spread, the late depolarization after the end of the QRS complex can be detected in the ECG as ventricular late potentials by means of high resolution systems. Ventricular late potentials may be regarded as indicative of increased electrical vulnerability of the ventricles. Prevalence of ventricular late potentials: In our own studies using the signal-averaged ECG technique, ventricular late potentials were found most frequently in patients with coronary artery disease and only in 6/100 healthy subjects, in 5/30 patients with dilated cardiomyopathy, in none of 30 patients with aortic stenosis or ten with "small vessel disease". With continuously-registered high resolution electrocardiography but not with the signal-averaged ECG, patients with dilated cardiomyopathy or QT-syndrome can be found to have labile, intermittent ventricular late potentials. In patients with coronary artery disease, the number of those in whom ventricular late potentials can only be detected with continuously-registered high resolution ECG in addition to signal-averaged technique lies between 6 and nearly 30%. With respect to frequency analysis of the ST-segment, which is based on the hypothesis that the fractionated signals in arrhythmogenic areas are of higher frequency than the normal low frequency signals of the ST-segment in normal myocardial areas, there is only limited experience and no data from larger collectives.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1990

[Clinical significance of intracardiac electrocardiography in the diagnosis of syncope].

An important advance in the diagnosis of arrhythmias as the cause of syncopes is the introduction of intracardiac electrocardiography and diagnostic electric stimulation known at present as clinical cardiac electrophysiology. The author examined a group of 70 patients with syncopes and divided them into two sub-groups. The first group comprised 46 patients examined by means of a hisogram and assessment of the recovery period of the sinus node and the second group 24 patients where the examination comprised in addition programmed stimulation of the right atrium and ventricle. In the first group the examination explained the cause of syncopes in arrhythmia in 22 patients (48%), in the second group in 12 patients (50%). In the entire group the invasive technique proved useful in 34 patients (49%). Based on the results of tests a therapeutic procedure was selected--implantation of a pacemaker or medicamentous antiarrhythmic therapy.

Aged↗

PubMed1989

Ambulatory electrocardiography in the elderly: an audit.

In a retrospective analysis of 264 episodes of ambulatory electrocardiography (AECG) in 252 elderly out-patients the overall diagnostic yield was only 12 per cent. However, AECG was found to be of significant value in detecting symptomatic tachyarrhythmias, and in confirming the diagnosis of the 'sick sinus syndrome'. The AECG results influenced the management plan in at least 16 per cent, and changes in drug treatment in 10 per cent. When interpreted critically, AECG is useful tool in the investigation of elderly patients with symptoms such as syncope, faintness, dizziness and unexplained falls.

Aged↗

PubMed1989

Ambulatory electrocardiography: an open-access service for general practitioners.

Access to ambulatory electrocardiography would enable general practitioners to investigate certain patients with cardiac symptoms without the need for hospital referral. An analysis has been made of the results in 200 consecutive patients referred to a pilot open-access service based at three health centres. Twenty-two GPs used the service, although there was a wide range (1-48) in the number of patients each referred. In 72 patients aged under 50 years, abnormalities other than extrasystoles were detected in only six; major significant arrhythmias were found in three patients, although treatment was required in only one case. Arrhythmias were frequent in patients aged over 50 years but were usually minor; 16/128 (13 per cent) showed major significant arrhythmias. Pacemakers were implanted in two patients. Palpitation and/or dizziness were reported during the period of monitoring by 39 per cent of patients (and were equally common in both age groups), but in neither age group did these symptoms correlate with the occurrence of a significant arrhythmia. In primary care, palpitation and dizziness are rarely due to significant arrhythmias. To increase the cost-effectiveness of the service, ambulatory monitoring could be restricted to patients over 50 years of age, except when there is other evidence of heart disease.

Adolescent↗

PubMedDate not supplied

Teaching electrocardiography: computer assisted learning vs lecture method.

This study investigated nursing students' responses to a basic electrocardiography computer assisted learning (CAL) program and a lecture on the same topic. There were no significant differences between the CAL and lecture groups on cognitive outcomes (measured by a 20 item test on electrocardiogram knowledge) or transfer of learning outcomes (measured in the clinical setting by the students' ability to identify and interpret six electrocardiogram tracings). However, CAL students displayed more positive affective responses. They also took between 10 and 32 minutes to complete the program while all lecture students took a mandatory 50 minutes or more.

Adult↗

PubMedDate not supplied

Efficacy of mexiletine in ventricular arrhythmias among patients in Taiwan: assessment by 24-hour Holter electrocardiography.

The effects of mexiletine in 30 patients with symptomatic recurrent ventricular arrhythmias were assessed by 24-hour Holter electrocardiography and M-mode echocardiography. The mean daily dose of mexiletine was 534 mg (range, 300 to 900 mg) and the interval of Holter follow-up was 16.9 days (range, 10 to 25 days). Total ventricular premature beats were reduced by 85% or more in 21 patients; in 19 of these patients there was a reduction of one or more modified Lown grades of ventricular arrhythmias. The overall reduction in Lown grades in the 30 patients was from 3.3 +/- 0.8 to 1.5 +/- 1.4 (P less than 0.0001). No significant changes in heart rate before or after mexiletine therapy were noted. Left ventricular echocardiography showed no significant changes in percentage fractional shortening after treatment. Adverse effects included gastrointestinal intolerance in seven patients and neurogenic symptoms in three. During the follow-up period of 1 to 11 (mean, 3.2) months, ventricular arrhythmias recurred in three patients. It is concluded that oral mexiletine is moderately effective and safe in controlling symptomatic recurrent ventricular arrhythmias.

Adult↗

PubMed1989

[Comparison of echocardiography, vectorcardiography, electrocardiography, coronarography and ventriculography in coronary heart disease].

Fifty patients (9 women, 41 men) with angina pectoris, aged from 22 to 59 years, were examined by means of one- and two-dimensional echocardiography (ECHO), vectorcardiography (VCG) using the McFee-Parungao system of leads, standard 12 lead electrocardiography (ECG), coronarography (CAG), and ventriculography (VG). I of isolated positivity of either of these methods ans considererl as patse positivity and presence or absence of positivity in combination of at least two methods (ECG exeluted) astme positivity, or true negativity then VCG was found to have the highest sensitivity (96%), negative predictive value (80%), as well as the highest overall predictivity (83%), while ECHO had the lowest values, i.e. 55%, 36%, 64%, respectively. On the other hand, ECHO was leading in specificity and positive predictive value with 100%, whereas VCG ranked lowest with 62% and 83% respectively. The combination of ECHO and VCG versus CAG and/or VG positivity exhibited and 80% specificity, 90% sensitivity, 90% positive predictive value and 86% overall predictivity when stenosis of over 50% was considered to be criterion. If obstruction was required the figures were to 75%, 94%, 83% and 86% respectively. ECHO and VCG are complementary noninvasive methods able to predict the results of CAG and VG and have a good predictive value when lowing for mere presence of focal myocardial injury.

Adult↗

PubMed1977

First-degree trifascicular block unmasked by sinus arrhythmias. Report of a case studied with intracardiac electrocardiography.

A case is presented in which first-degree block in all three fascicles of the intraventricular conduction system results in a QRS complex with no specific features of fascicular block. During spontaneous sinus arrhythmia the typical features of RBBB and LAH appear at the longest sinus cycles. This is associated with shortened P-R and H-Q intervals. During shorter sinus cycles, near equalization of delay in each fascicle is associated with delay in His-Purkinje conduction but loss of the typical features of bifascicular block as the ventricular myocardium becomes activated more synchronously. Documentation of the changing patterns of ventricular activation is provided by His bundle electrocardiography.

Adult↗

PubMed1988

The inverse problem in electrocardiography: solutions in terms of epicardial potentials.

The objective of the inverse problem in electrocardiography is to recover noninvasively regional information about intracardiac electrical events from electrical measurements on the body surface. The choice of epicardial potentials as the solution to the inverse problem is motivated by the availability of a unique epicardial potential solution for each body surface potential distribution, by the ability to verify experimentally the inverse-recovered epicardial potentials, by the proven relationship between epicardial potentials and the details of intracardiac regional events, and by the possibility of using the inverse solution as a supplement or possible replacement to clinical epicardial potential mapping prior to surgical intervention. Although, in principle, the epicardial potential distribution can be recovered from the body surface potential distribution, the inverse problem in terms of potentials is ill-posed, and naive attempts to reconstruct the epicardial potentials result in incorrect solutions which are highly oscillatory. Large deviations from the actual solution may result from inaccuracy of the data measurement, incomplete knowledge of the potential data over the entire torso, and inaccurate description of the inhomogeneous torso volume conductor. This review begins with a mathematical and qualitative description of the inverse problem in terms of epicardial potentials. The ill-posed nature of the problem is demonstrated using a theoretical boundary value problem. Effects of inaccuracies in the body surface potential data (stability estimates) are introduced, and a sensitivity analysis of geometrical and inhomogeneity parameters is presented using an analytical eccentric spheres model. Various computational methods for relating epicardial to body surface potentials, i.e., the computation of the forward transfer matrix, are described and compared. The need for regularization of the inverse recovery of epicardial potentials, resulting from the need to invert the ill-conditioned transfer matrix, is demonstrated. Several regularization techniques are compared in terms of their performance regarding noise in the data and inaccuracies in geometry and inhomogeneities. Finally, several existing, regularized inverse procedures that compute epicardial potentials from measured body surface potential data are introduced and compared. The review concludes with a section that points toward future directions for improving the quality of the inverse-reconstructed epicardial potentials. Future directions for the use of the inverse problem to obtain epicardial potential distributions noninvasively in both experimental animals and patients in a clinical se

Animals↗

PubMed1986

[Diagnostic significance of electrocardiography and myocardial scintigraphy with 99m Tc-Sn-pyrophosphate and 99m Tc-Sn-phosphone in patients with stenocardia].

Altogether 123 angina patients were examined using electrocardiography and scintigraphy of the myocardium with two 99m Tc radiopharmaceutical complexes: pyrophosphate and phosphone. A comparative analysis of the results obtained with different methods of investigation before and after an attack of angina pectoris was made. The authors have shown some peculiarities of radionuclide distribution in the myocardium and the diagnostic value of each method of investigation in patients with different clinical forms of angina pectoris.

Angina Pectoris↗

PubMed1988

High-resolution electrocardiography.

The electrocardiogram (ECG) is arguably the most common noninvasive diagnostic test performed by physicians. The instrumentation for recording the ECG has followed technological trends but the addition of new information has not generally been forthcoming from these advances. Instead, the elucidation of the standard waves P, QRS, T, and U is still the primary focus of electrocardiographic recording and interpretation. High-resolution electrocardiography can be defined as the use of methods to record physiological information not measurable with the standard ECG while still maintaining a noninvasive approach. Often these newer methods require digital signal processing for enhancing very low-level signals, deriving parameters from stored waveforms, or adaptively changing filter characteristics to record the normal wave when contaminated with high levels of noise. This review examines most of these approaches but concentrates on the methods which allow the recording of new information which may have significant diagnostic and, perhaps, prognostic value.

Animals↗

PubMed1987

[Friedrich Kraus--originator of functional diagnosis and electrocardiography in Germany].

The 50th anniversary of the death of Friedrich Kraus (31 May 1858 to 1 March 1936) was the occasion to remind of the merits of this internist for the development of the functional diagnostics and the spreading of the electrocardiography in Germany. After the first professorship in Graz (foundation of the constitution research) he was appointed director of the 2nd Medical Clinic of the Charité in Berlin 1902, where he worked up to his discharge from the active service in 1927. From 1906 he dealt with electrocardiological problems, mainly together with G.F. Nicolai (1874-1955). In 1910 the first monography on "The Electrocardiogram of the Healthy and Ill Man" was published. After World War I Kraus dealt with the "Special Pathology and Therapy of Internal Diseases" and the "General and Special Pathology of the Person". In the theory of the depth person, being ahead of the time, psychosomatic connections were explained. A selective bibliography of the most important works of Kraus is added to the paper.

Electrocardiography↗

PubMed1987

[Role of ambulatory electrocardiography in the evaluation of interventions: rehabilitation of a patient who has undergone surgery].

The authors relate their own experience with 24 hr Holter monitoring in course of cardiac rehabilitation after coronary bypass surgery as well as after valvular replacement. As regards patients after coronary surgery they report the experience they got in the evaluation of heart rate trend and cardiac arrhythmias as well as in silent ischemia study. About this last problem 116 patients with signs of ischemia both in stress test and in Holter recording are considered out of 491 who had undergone coronary surgery. Ischemia during 24 hr Holter monitoring develops at an heart rate lower than effort ischemia. Holter monitoring proves to be very useful also in patients after valvular replacement to study arrhythmias and to check drugs' efficacy. After displaying the results concerning arrhythmias of 24 hr Holter electrocardiograms recorded in 207 randomized patients who had undergone valvular replacement 15 days before, the authors dwell upon the use of Holter electrocardiography in 82 valvular patients after pharmacological cardioversion and show that major arrhythmias get a clear reduction thanks to rehabilitation.

Adult↗

PubMed1977

Use of computers in clinical electrocardiography: an evaluation.

The use of computers in clinical electrocardiography is increasing rapidly; however, the role of computers with respect to the electrocardiographer has not been established. At present all electrocardiograms (ECGs) processed by computer are also interpreted by electrocardiographers; hense effort is duplicated. In an investigation of whether conditions can be defined under which the electrocardiographer can use the computer more profitably by eliminating some of the duplication, ECGs recorded in a university teaching hospital were processed by a computer program and subsequently reviewed by 1 of 10 electrocardiographers. For ECGs interpreted as showing normal sinus rhythm the rate of agreement between computer and human reviewer was 99%. For those showing a normal ECG pattern (contour) the rate of direct agreement was only 88%. However, the rate of occurrence of clinically significant differences was only 1.64%; hence the rate of essential agreement for this classification was 98.36%. Other classifications with good agreement were myocardial infarction, sinus bradycardia and sinus tachycardia. Therefore, in circumstances comparable to those of this investigation it is feasible for electrocardiographers to use computers to reduce greatly their workload without compromising the quality of the service provided.

Bradycardia↗

PubMed1987

[Myocardial ischemia with negative stress electrocardiography: evaluation by stress RI studies].

Patients with negative stress electrocardiography (ECG) (no ST segment depression) were re-evaluated by means of stress RI studies including 201T1 single photon emission computed tomography (SPECT) and 99mTc-RBCs radionuclide ventriculography (RNV). Four hundred seven patients, including 303 with old myocardial infarction (OMI; SPECT: 188, RNV: 115) and 104 with effort angina (EA; SPECT: 58, RNV: 46), all of whom underwent left ventriculography and coronary arteriography, were re-evaluated by symptom-limited graded bicycle ergometer exercise RI testing. The results were as follows: 1. Among those with negative stress ECG (53% of OMI and 31% of EA), 54% and 73% of OMI and EA, respectively, had positive SPECT. 2. Among those with negative stress ECG (56% of OMI and 39% of EA), 70% and 39% of OMI and EA, respectively, had positive delta EF (poor increase in ejection fraction: delta EF less than 5%) and, 41% and 28% of OMI and EA had deteriorated regional wall motion. 3. Those with OMI and negative ECG showed no correlations with the numbers of diseased vessels, infarcted sites, or ischemic areas. In conclusion, RI testing appears to be a significantly more sensitive means of detecting stress-induced ischemia, compared to stress ECG.

Adult↗

PubMed1986

[The telemetric emergency electrocardiography--practical use and methodologic effectiveness].

The study of 797 emergency provisions shows that it is possible to improve the implementation of internal emergency measures in respect of operation and safety by means of telemetric emergency-electrocardiography by eliminating electric cables and their resulting interference factors. Thereby the proper signal receiving by fixed thorax electrodes or a maintenance-free electrode-transmitter unit serving as an "electronic emergency electrode" meets the requirements of the case of emergency for an ECG-recording under mechanical stress or without delay. The application of this procedure is especially recommended for emergency and danger situation in which cabling is connected with risks as to operation and safety. After providing all the technical preconditions for the wireless communication telemetric signal transmitting is unreservedly to be applied for practical emergency provision.

Arrhythmias, Cardiac↗

PubMed1978

History of precordial leads in electrocardiography.

Precordial leads were first used by Waller, whose capillary electroscope was too insensitive to detect the electric forces emanating from the human heart unless the electrode was placed over the precordium as near to the heart as possible. When Einthoven developed the elegant, reliable and sensitive string galvanometer, he could record the electric forces of the heart from the hands and feet of the subject without even undressing him. When Einthoven's great galvanometer became available, only the three standard limb leads were used. Thomas Lewis and others experimented with precordial direct leads and made many important discoveries in electrocardiography and cardiology. Wolferth and Wood, in 1932, introduced the first precordial lead in clinical, diagnostic cardiology. The recordings were 'upside-down', i.e. positive deflections were down and negative ones up. They called this the 4th lead (lead IV). The precordial electrode was placed on the chest over the apex of the heart, regardless of where the apex was located. This immediately opened new avenues of study in infarction, ventricular hypertrophy, bundle branch block, and all other cardiac states. Then CL, CR, CF, CB and V leads were introduced. The points considered best for placing the 'exploring' or precordial electrode became an issue, and much confusion prevailed until Wilson and his associates developed the central or isopotential terminal and until the American Heart Association and the Heart Society of Britain and Ireland met in London and published the standards for recording precordial leads in 1938. There followed, for obvious reasons, a slow settling of the confusion until the V1 through V6 precordial leads became standard procedure all over the world, as exists today. Goldberger introduced the augmented unipolar limb leads (aVR, aVL and aVF) which have resulted in the standard 12-lead electrocardiogram of routine use today. No one would consider an electrocardiographic evaluation adequate in a cardiac study at present unless the 12-lead ECG were recorded.

Animals↗