[Simple interpretation of the electrocardiogram. 6. Left and right ventricular hypertrophy and the electrocardiogram].
Explore the source record for details and available documents.
Cardiomegaly↗
SEARCH · PubMed Health
Results for “Electrocardiogram”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[Recommendations for the evaluation and interpretation of juvenile electrocardiograms. Short programmed course. 14. (4. supplement): The electrocardiogram in athletes and in pupils and juveniles during athletic training].
Explore the source record for details and available documents.
Adolescent↗
The electrocardiogram in acute pulmonary embolism.
Electrocardiograms of 90 patients with arteriographically documented acute submassive or massive pulmonary embolism and no associated cardiac or pulmonary disease were studied. Patients were derived from the Urokinase-Pulmonary Embolism Trial National Cooperative Study. In massive embolism, the electrocardiogram was normal in 6 per cent (3 of 50) of patients. With submassive embolism, 23 per cent of patients (9 of 40) had a normal electrocardiogram. Since one or more of the traditional manifestations of acute cor pulmonale (S1Q3T3, right bundle branch block, P pulmonale, or right axis deviation) occurred in only 26 per cent of patients, one could not rely exclusively upon these electrocardiographic abnormalities for the diagnosis of pulmonary embolism. The most common electrocardiographic abnormalities were nonspecific T wave changes which occurred in 42 per cent of patients and nonspecific abnormalities (elevation or depression) of the RST segment which occurred in 41 per cent of patients. Left axis deviation occurring in 7 per cent of the patients was as frequent as right axis deviation. Low voltage QRS complexes, previously undescribed in pulmonary embolism, occurred in 6 per cent of patients. None of the patients had atrial flutter or atrial fibrillation, which appears to occur more typically in patients with pulmonary embolism who have preexistent cardiac disease. All of the varieties of electrocardiographic abnormalities disappeared in some of the patients by 2 wk. Inversion of the T wave was the most persistent abnormality. Larger defects on the lung scan or pulmonary arteriogram occurred in patients with various abnormalities on the electrocardiogram than in patients with normal electrocardiograms. The pulmonary arterial mean pressure and/or right ventricular end-diastolic pressure was significantly higher in patients with several varieties of abnormal electrocardiograms, although the partial pressure of oxygen in arterial blood, in general, did not differ from that in patients with normal electrocardiograms. These hemodynamic correlations, made for the first time in patients, suggest that acute ventricular dilatation, possibly in combination with hypoxemia, is a causative factor of the electrocardiographic changes in acute massive or submassive pulmonary embolism.
Acute Disease↗
The electrocardiogram in ambulatory medical practice.
The electrocardiogram is one of medicine's most frequently ordered procedures. A review of the current use of electrocardiograms in ambulatory clinical practice and the possible information that might be supplied by an electrocardiogram was undertaken. The electrocardiogram's advantages and disadvantages when used in evaluating specific cardiac disorders are discussed including the use of the electrocardiogram as a baseline. Both their values and their limitations in diagnosis and management are examined to support the authors' conclusion that electrocardiograms should be used as an adjunct to clinical diagnosis, not as a screening procedure.
Ambulatory Care↗
[Coronary stenosis in angina pectoris with normal resting electrocardiogram].
The arteriographic abnormalities found in 104 patients with typical angina pectoris and an electrocardiogram at rest which was normal at the time of arteriography were compared with those of 238 cases with typical angina pectoris, but with an abnormal electrocardiogram (127 having ST/T changes, 111 having transmural necrosis). There was no major difference between the two groups as far as the degree of coronary stenosis was concerned, nor in its extent and distribution. However, by comparison with the group with an abnormal electrocardiogram, very tight stenoses of the three trunks or of one trunk alone were slightly less common in the patients with a normal electrocardiogram; also, for each of the three trunks, the index of the lesion was slightly less raised, and the circumflex and right coronary arteries were slightly less commonly, affected, although the difference was not usually great enough to achieve significance. The action of the left ventricle and/or the value of left ventricular end-diastolic pressure were, however, manifestly better conserved in those with a normal electrocardiogram (p less than 0.001). An aorta-coronary bypass graft is more likely to be indicated in this group of patients.
Adult↗
Thallium-201 myocardial imaging in evaluation of asymptomatic individuals with ischaemic ST segment depression on exercise electrocardiogram.
Asymptomatic adults with normal physical examination, normal resting electrocardiogram, and normal routine laboratory evaluation who have a positive exercise electrocardiogram and abnormal exercise thallium-201 myocardial image have a very high probability of angiographically significant coronary artery disease. If, on the other hand, the exercise electrocardiogram is positive for "ischaemic" ST segment changes, but the exercise thallium image is normal, the probability for coronary disease is low. The exercise electrocardiogram combined with thallium-201 myocardial image are safe non-invasive methods which can be performed on an out-patient basis.
Adult↗
Serial electrocardiograms in hypertensive cardiovascular disease.
A graphic method for depicting serial changes in electrocardiograms is described and demonstrated for patients being treated in an antihypertension clinic. For these patients, the diagnostic categories, normal, left ventricular hypertrophy, and biventricular hypertrophy, are of primary interest. For each electrocardiogram, 14 measurements are used to compute posterior probabilities for each of the three categories. A triangular grid is used to plot each set of probabilities for an electrocardiogram as one point, which by its position in the triangle can be related to the three categories simultaneously. Points representing successive electrocardiograms can be plotted in the same triangle, giving a pattern of change with time. This pattern of change has been corroborated with associated clinical information on a number of patients. This display, which can be produced quickly and efficiently on a computer graphics terminal, should be considered as a possible tool in evaluating the status of individual hypertensive patients in terms of increase or decrease of ventricular hypertrophy and the efficacy of therapeutic measures.
Aged↗
Value of electrocardiogram in predicting and estimating infarct size in man.
The value of the electrocardiogram in assessing infarct size was studied using serial estimates of the MB isomer of creatine kinase (CK MB) in plasma, serial 35 lead praecordial maps in 28 patients with anterior myocardial infarction, and serial 12 lead electrocardiograms in 17 patients with inferior myocardial infarction. In patients with anterior infarcts, sigma ST, sigma R, sigma Q, sigma R/(Q+S), and the number of sites with ST elevation more than 2 mm or with QS waves, were obtained from each map. Correlation between both maximum sigma Q and maximum sigma ST with cumulative CK MB was highly significant. There was also a significant correlation between sigma R and sigma R/(Q+S) with cumulative CK MB. There was no significant correlation between maximum number of sites with ST elevation or with Q or QS waves and cumulative CK MB. Maximum sigma ST and number of sites with ST elevation predicted maximum sigma Q and number of sites with QS or Q waves at a time when infarction was not complete. In patients with inferior infarcts, there was a significant correlation between maximum sigma Q and maximum sigma ST in leads II, III, and a VF, and cumulative CK MB. This study shows that all the waves in the electrocardiogram are useful in assessing infarct size. The fact that maximum sigma ST predicts final sigma Q may be used to assess the efficacy of interventions designed to salvage ischaemic myocardium.
Aged↗
The effects of acute severe arterial hypoxemia on the electrocardiogram during exercise.
Sixteen healthy, active men were studied to determine the effects of severe arterial hypoxemia on the electrocardiograms during exercise. The electrocardiograms were all normal at maximum heart rate while the subject breathed ambient air. During maximal exercise breathing ten percent oxygen (mean arterial oxygen pressure [Po2] of 31 mm Hg), only one of the 16 had ST segment changes suggestive of ischemia. These were not present on a repeated study. The widely held view that systemic hypoxemia causes ischemic changes on the electrocardiogram was not confirmed in this study.
Acute Disease↗
[Diagnostic value of Frank's corrected orthogonal electrocardiogram].
The changes in the corrected orthogonal electrocardiograms of 411 patients were analyzed: 134 with right ventricle loading, 137 with left ventricle loading and 140 with myocardial infarction (chronic phase). On the base of sensitivity and specificity criteria the indices SXmV, SXmsec and QZmV for the patients with right ventricle loading and RXmV and RZmV for the patients with left ventricle loading proved to be with the highest diagnostic value. Sensitivity is within 19% to 61%. Sensitivity is within 85% and 95% in patients with myocardial infarction (chronic phase), for the different indices depending on the infarction zone. The comparative analyses of the indices of the corrected orthagonal Frank electrocardiogram and the standard electrocardiogram (12 leads) give a certain preference to the indices of the standard electrocardiography.
Cardiomegaly↗
Exercise testing for detection of myocardial ischemia in patients with abnormal electrocardiograms at rest.
This review consists of two parts: (1) discussion of the electrophysiologic mechanisms that are believed to produce ventricular repolarization changes during the electrocardiographic stress test, and (2) clinical assessment of the electrocardiographic changes with stress in patients with an abnormal electrocardiogram at rest. In the first part, the mechanisms of S-T segment elevation, S-T segment depression, T wave changes and linked S-T and T wave changes are reviewed. In the second part, all electrocardiographic abnormalities at rest are grouped into four categories: (1) changes that mask the manifestations of ischemia, (2) changes that stimulate or exaggerate the manifestations of ischemia, (3) changes that have no important effect on the manifestations of ischemia, and (4) changes that reproduce the patterns of acute myocardial infarction after an apparent healing. The reported studies of electrocardiographic stress testing in patients who have abnormal electrocardiogram at rest are summarized.
Action Potentials↗
Altered adrenergic activity in coronary arterial spasm: insight into mechanism based on study of coronary hemodynamics and the electrocardiogram.
To elucidate the pathophysiologic mechanism of coronary arterial spasm, the hypothesis was examined that underlying alterations in sympathetic activity may account for this syndrome in some patients. Observations were directed to alterations in coronary arterial hemodynamics and the electrocardiogram. Spasm of the left anterior descending coronary artery produced a mean increase in coronary vascular resistance of 107 percent (P less than 0.05) in four patients in whom coronary sinus blood flow was measured with the thermodilution technique. The alpha adrenergic blocking agent phentolamine, given intravenously, acutely reversed coronary spasm and its clinical manifestations in eight patients and reduced coronary resistance. In four patients, administration of the long-acting oral alpha blocking agent phenoxybenzamine (20 to 80 mg/day) caused disappearance of symptoms during a follow-up period of 3 to 12 months. Transient prolongation of the corrected Q-T interval preceded spontaneous or ergonovine maleate-provoked coronary spasm in 11 patients with variant angina pectoris, whereas no significant change in the Q-T interval followed ergonovine administration in 27 control patients with atypical chest pain who did not have coronary spasm. T wave inversions in the resting electrocardiogram were normalized by isoproterenol infusion in one patient and by long-term phenoxybenzamine treatment in four patients with variant angina pectoris. These Q-T and T wave changes are analogous to those described with unilateral or asymmetric stellate ganglion stimulation in animals. These observations suggest that alterations in the sympathetic nervous system that are consistent with asymmetric stellate ganglion activity and transient alpha adrenergic receptor stimulation can presage the development of coronary arterial spasm in some patients with variant angina pectoris.
Adult↗
Clinical evaluation of automated processing of electrocardiograms by the Veterans Administration program (AVA 3.4).
Automated processing of electrocardiograms by the Veterans Administration program was evaluated for both agreement with physician interpretation and interpretative accuracy as assessed with nonelectrocardiographic criteria. One thousand unselected electrocardiograms were analyzed by two reviewer groups, one familiar and the other unfamiliar with the computer program. A significant number of measurement errors involving repolarization changes and left axis deviation occurred; however, interpretative disagreements related to statistical decision were largely language-related. Use of a printout with a more traditional format resulted in agreement with physician interpretation by both reviewer groups in more than 80 percent of cases. Overall sensitivity based on agreement with nonelectrocardiographic criteria was significantly greater with use of the computer program than with use of the conventional criteria utilized by the reviewers. This difference was particularly evident in the subgroup analysis of myocardial infarction and left ventricular hypertrophy. The degree of overdiagnosis of left ventricular hypertrophy and posteroinferior infarction was initially unacceptable, but this difficulty was corrected by adjustment of probabilities. Clinical acceptability of the Veterans Administration program appears to require greater physician education than that needed for other computer programs of electrocardiographic analysis; the flexibility of interpretation by statistical decision offers the potential for better diagnostic accuracy.
Cardiomegaly↗
Comparison of the electrocardiogram and vectorcardiogram for the diagnosis of left atrial enlargement.
Standard 12 lead electrocardiograms (ECG) and Frank vectorcardiograms (VCG) were recorded in 21 consecutive patients with mitral valvular disease and angiographically documented left atrial enlargement. Comparative sensitivities for the detection of left atrial enlargement were: diagnostic, ECG = 6/21 (29%), VCG = 14/21 (67%); suggestive, ECG = 3/21 (14%), VCG = 2/21 (9%); non-diagnostic, ECG = 12/21 (57%), VCG = 5/21 (24%). It is concluded that the Frank atrial vectorcardiogram is superior to the standard electrocardiogram for the diagnosis of left atrial enlargement.
Adult↗
The electrocardiogram in the assessment of the effect of drugs on cardiac arrhythmias.
The search for the ideal antiarrhythmic drug continues since none of the available agents offers optimum antiarrhythmic therapy. The continuing search coupled with the interest in the mechanisms of cardiac arrhythmias has led to the development of new techniques for the study of arrhythmias and antiarrhythmic drugs. In this article it is proposed to discuss the electrocardiographic methods used in the assessment of antiarrhythmic drugs. Firstly, to discuss the electrocardiogram in the assessment of the clinical electrophysiological properties of a drug and secondly, the electrocardiogram in the assessment of the value of the drug in the management of cardiac arrhythmias in man.
Arrhythmias, Cardiac↗
Instrumentation for the follow-up of pacemade patients. Telephone transmission of the electrocardiogram and self-check by the patient on pacemaker function and capture.
Logic circuitry has been added to an electrocardiogram telephone transmitter. It processes the electrocardiogram and permits frequent self-checks by the patient on rate, capture and sensing function of an implanted demand pulse generator system. Correct function is communicated to the patient by a green light. Malfunction with regard to any of these parameters produces an irreversible yellow light signaling the patient to contact his physician. The self-check is reassuring to the patient during intervals between visits to the physician's office or a specialized clinic. The system, at present, is applicable only to demand pulse generators with a high magnet test rate (90 ppm or higher) which assures capture in virtually all patients. This and other limitations are discussed. Their incidence is low, some can be remedied and in the majority of patients they do not impair the clinical usefulness of the system.
Electrocardiography↗
Relationship between plasma calcium and QT interval of electrocardiogram in dairy cows.
Relationships between calcium of blood plasma and measurements of the electrocardiogram QT interval corrected for heart rate and interval from Q to the apex of T corrected for heart rate were investigated in six dairy cows. Calcium was varied by infusing 4.7% solution of ethylenediaminetetra-acetic acid disodium salt to induce hypocalcemia, followed by treatment with calcium borogluconate. The within-cow regressions of the intervals on calcium in plasma were significant in all four electrocardiogram leads (leads I, aVF, SIII, and SaVF). These regressions differed between cows in these same leads. Correlation coefficients between calcium and the intervals were consistently larger than --.94 in lead SIII in all cows. When the results from four of the cows similar in age and breed were analyzed separately, regression coefficients between individual cows were not significantly different. However, intervals adjusted for calcium in plasma differed between cows.
Animals↗
[Electrocardiogram in interstitial pneumonia. Electrocardiographic-hemodynamic correlation].
Twenty four patients with interstitial pulmonary disease from the Cardiopulmonary Service of the Instituto Nacional de Cardiología were studied. Surface electrocardiograms and pulmonary hemodynamic studies were registered to all patients in order to obtain the pulmonary vascular resistances and pressures to find out the electrocardiographic-hemodynamic correlation. Three groups were made according to the pulmonary artery sistolic pressure: Group I, 30 to 45 mm Hg (6 patients); Group II, 46 to 70 mm Hg (12 patients) and Group III more of 60 mm Hg (6 patients). Also, arterial gaseous partial pressures were determined, among other pulmonary test parameters. Electrocardiographically, the rhythm, A=V node conduction, AQRSF, APF, atrial and ventricular hypertrophy, intraventricular conduction and ventricular repolarization were studied in leads II, III, aVF, aVR, V1, V2, V3 and V6. The characteristics of the ventricular repolarization and depolarization processes of each group are described, in order to discuss the mechanism of the anormalities. Finally, the electrocardiographic findings were correlated with the different degrees of pulmonary arterial hypertension; the conclusions are: I. The electrocardiogram allows us to differenciate the patients with III degree of arterial pulmonary hypertension, from those of I and II degrees. II. Patients with I and II degrees of pulmonary arterial hypertension determine nearly the same electrocardiographic alterations; the mean differences to establish the differential diagnosis is the AQRSF, shifted to the right and upwards, in the II degree of pulmonary arterial hypertension.
Adult↗