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Query: UMLS:C0151744 (myocardial ischemia)
 31,282 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The criteria for the diagnosis of myocardial infarction and ischaemic heart disease by an automated 15-lead computer-aided electrocardiographic system were examined using electrocardiograms of 543 patients. Errors in the electrocardiographic diagnosis were evaluated for each lead system (Frank orthogonal 3-lead, 12-lead, and hybrid 15-lead) using clinical and catheterization data for definitive diagnosis before review of the electrocardiograms and their reports. The effects of combinations of these diagnoses and additional ventricular conduction defects were also studied. Myocardial infarction and left ventricular hypertrophy were more reliably diagnosed using 3-lead and 12-lead systems together than with either system alone. The most sensitive criteria for anterior infarction were a Q/R ratio in Z less than 0-1 and loss of the first 20 ms of anterior forces in the horizontal and sagittal planes of the vectorcardiogram. However, false positive results were frequent, particularly in association with left ventricular hypertrophy, non-specific intraventricular conduction defects, and left bundle branch system block. Our V lead criteria were more specific whether or not these associated conditions were present. No single criterion with an acceptable false positive rate could be found to be sensitive for inferior infarction in all situations. Our most sensitive criteria were those based on the limb leads, and the presence of superior forces for the first 30 ms in the frontal plane of the vectorcardiogram, but these were better in combination. Limb lead criteria were the most specific. False positive results for inferior infarction were more frequent in the presence of left ventricular hypertrophy or ventricular conduction defects other than left anterior hemiblock. ST and T wave abnormalities were more apparent in the 12 leads than in the orthogonal leads. Specificity and sensitivity of criteria were poor, and specificity was decreased and sensitivity was not significantly improved by combining 3-lead with 12-lead criteria. Because of frequent measurement errors of ST, T, and also Q waves by the computer programme, in practice we have achieved increased sensitivity in the diagnosis of ischaemia and infarction with the combination of 3-lead and 12-lead systems. It is concluded that errors of diagnosis by a computer-aided system can be reduced by using multiple leads and that both 12-lead and orthogonal 3-lead systems are necessary for optimal computer diagnosis of left ventricular hypertrophy, myocardial infarction, and ischaemia.
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PMID:Diagnostic criteria for computer-aided electrocardiographic 15-lead system. Evaluation using 12 leads and Frank orthogonal leads with vector display. 13 30

In 12 patients with symptomatic coronary heart disease and three normal persons, comprehensive analyses of the electrocardiographic changes associated with symptom-limited upright exercise are made by computer analysis of the electrocardiogram recorded using a Frank XYZ lead system. This analysis provided a display of the 12 lead ECG, vectorcardiogram, polarcardiogram, and spatial cardiogram and measurements of spatial magnitudes of heart vectors. The effect of 40 mg of oral propranolol was assessed by repeating the exercise protocol 60--90 min later. There is evidence that propranolol reduces the electrocardiographic features of myocardial ischemia. This reduction in myocardial ischemia correlates with reductions in pressure rate product and heart rate. The presence of infarct criteria with exercise is variable and not apparently influenced by propranolol.
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PMID:Comprehensive analysis of exertional ECG changes before and after oral propranolol. 26 76

Comparison of data obtained in recording corrected orthogonal leads of the Frank system and 12 classical ECG leads in 118 patients with ischemic heart disease, among whom there were 76 patients with an old myocardial infarction, showed that corrected orthogonal leads may be used in mass population survey with the use of automatic diagnostic machines. It was established that the following ECG indices may be used in recording Frank's corrected orthogonal leads in the diagnosis of cicatricial myocardial changes: amplitude and duration of Q wave, the Q/R and R/S coefficients, the appearance of wave S in lead "Z". In an old myocardial infarction of posterior localization changes are recorded in lead "Y", in infarction of antero-septal localization changes are recorded in lead "Z" and to a lesser degree in lead "X"; in infarction of antero-lateral localization changes are recorded in lead "X" and to a lesser degree in lead "Z".
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PMID:[Diagnostic value of the system of Frank's orthogonal leads in inveterate myocardial infarct]. 43 97

In 104 patients with various type of bundle branch block the three most known systems of orthogonal ECG leads (Frank; McFee-Parungao; Beswick-Jordan) were compared with 12 routine leads. All three orthogonal systems proved to possess good informative value, not inferior to that obtained by routine ECG. Examinations of 123 patients suffering from ischaemic heart disease with signs of diffuse myocardial changes with the aid of the Frank's system of orthogonal ECG confirmed the high informative value of the system in the detection of local disturbances of intraventricular conduction. Criteria of evaluation of orthogonal ECG tracings in the detection of left anterior, right, and left bundle branch block were elaborated. The high informative value and limited number of leads recommend the orthogonal ECG system for wide practical use.
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PMID:Diagnosis of intraventricular conduction disturbances with the aid of orthogonal electrocardiography. 54 72

The effect of verapamil on ST changes was evaluated in 10 selected patients with acute myocardial infarction admitted to the Coronary Care Unit within 8 hours after the onset of symptoms. To evaluate the extent of ischemia it has been used the magnitude and direction of the ST vector derived from X, Y and Z leads of the Frank vector system. After a control period of 2 hours, during which the changes of the ST vector magnitude were assessed, each patient received 0.1 mg/Kg verapamil intravenously, ST vector magnitude (STVM), ST azimuth (STAZ), ST elevation (STEL), heart rate, systemic blood pressure and pressure-rate product were assessed 5, 15, 30, 45, 60, 75, 90, 105 and 120 minutes after the administration of the drug. Verapamil produced a significant progressive decrease in STVM (from a mean of 254 +/- 44 muV at the end of the control period, to 139 +/- 25 muV after 2 hours; P < 0.01). Systolic blood pressure decreased significantly throughout the trial; the most significant decrease was registered immediately after the infusion of verapamil (from a mean of 134 +/- 3 mmHg to 121 +/- 3 mmHg; P < 0.001). Pressure-rate product declined slightly. No significant change in STVM was observed in 10 control patients with acute myocardial infarction examined over a 4 hours period. The apparent protective effect of verapamil in myocardial ischemia is discussed in relation to its calcium-antagonistic properties in excitable tissues.
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PMID:[Effects of acute infusion of verampil on the ST segment elevation measured with the Frank orthogonal leads in patients with acute myocardial infarct]. 54 89

The extent to which an increase in preload increases left ventricular (LV) end-diastolic (ED) diameter (D) was studied in seven conscious dogs instrumented with ultrasonic D transducers and miniature LV pressure (P) gauges. Preload was elevated by three techniques: 1) volume loading with saline infusion, 2) induction of global myocardial ischemia by constricting the left main coronary artery, and 3) infusion of methoxamine. These three interventions increased LVEDP to over 30 mmHg from a control of 10 +/- 1 mmHg. With volume loading, LVEDD rose by only 1.55 +/- 0.39 mm from a control of 44.08 +/- 1.08 mm; with ischemia LVEDD rose by only .96 +/- .29 mm from a control of 42.55 +/- 2.18 mm, while with methoxamine LVEDD rose by only 1.34 +/- 0.38 mm from a control of 43.89 +/- 2.07 mm. In contrast, in the open-chest, anesthetized dog, LVEDD was greatly reduced and volume expansion resulted in a profound increase in LVEDD. Thus, the Frank-Starling mechanism is not an important controlling mechanism in the normal, reclining, conscious animal, since LVEDD appears to be near maximal at rest and does not increase substantially despite striking increases in LVEDP.
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PMID:Extent of utilization of the Frank-Starling mechanism in conscious dogs. 64 72

The article deals with the data of echocardiographic examination of 61 patients (37 with rheumatic heart disease and 17 with atherosclerotic cardiosclerosis) subjected to rapid stage-by-stage digitalization by intravenous administration of various rapidly acting glycosides. In 10 patients with ischemic heart disease echocardiography was performed following a single strophanthin injection. Decrease in the volumes of the left ventricle and increase in the indices of central hemodynamics were noted as a result of rapid stage-by-stage saturation with strophanthin. The maximum inotropic effect of strophanthin does not coincide in time with the maximum chronotropic effect. The increase in the stroke volume noted in maximum deceleration of cardiac contractions is probably realized due to the Frank-Starling mechanism. Strophanthin increases the rate of myocardial contractions without changing the duration of the systole. The rate of diastolic relaxation grows, the phase of rapid filling becomes shorter and the phase of slow filling longer, which creates favourable conditions for the next contraction.
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PMID:[Effect of rapid digitalization on the left-ventricular myocardial function according to the echocardiographic data]. 92

Polarcardiograms (PCG) derived from xyz leads of the Frank electrocardiogram (ECG) were recorded in the supine position in 1264 initially healthy middle-aged Chinese men who had been under continuing medical surveillance and were re-examined seven years later. Polarcardiographic criteria for myocardial infarction (MI) were demonstrated in 97 men (7.7%), but only 15 of them showed diagnostic Q waves in the electrocardiogram (ECG). Polarcardiographic criteria for MI were independent of age, but ranged from 4.3% in 464 apparently normal men to 38% in 21 men with manifestations of ischemic heart disease. The possible association of polarcardiographic criteria and a history of smoking was limited to those with clinical evidence of heart disease. The "false positive" rate of 4.3% in clinically normal men was similar to that reported in younger Canadians and in Cretan population samples.
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PMID:Polarcardiographic criteria for myocardial infarction in Chinese men. 97 81

In 100 patients with chronic ischaemic heart disease and diffuse changes in the myocardium the data of 12 common ECG leads indicated that the corrected orthogonal leads according to Mac Fee--Parungao and Frank reflect these changes in all cases. The severity of the diffuse changes reflected in the deviations of the ST segment and the T-wave in the orthogonal leads corresponds to that reflected in the 12 common leads. A mathematical analysis of the waves of the QRS complex in the X, Y and Z leads indicates a growth of the left ventricular potentials with the development of diffuse myocardial changes. The mentioned systems of orthogonal leads can be recommended for wide employment for the diagnosis of diffuse changes in the myocardium in ischaemic heart disease.
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PMID:[Diagnosis of diffuse myocardial changes in ischemic heart disease using orthogonal ECG leads]. 97 67

In order to find new ischaemic parameters, the spatial changes of the Frank vectorcardiogram were continuously analysed with a new, highly precise vectorcardiographic method during, and immediately after a maximal exercise test. This was done in 18 young healthy males, and 18 patients with scintigraphic reversible ischaemia. During exercise, different patterns between the groups were noted for the changes in the mean QRS magnitude in the Y-lead (P less than 0.005), the QRS-integral (P less than 0.05), and the QRS-duration (P less than 0.05). Immediately after exercise, several QRS parameters in the normal group continued to change according to the same pattern as during exercise (P less than 0.05), which was in contrast with the patterns of the ischaemic group (P less than 0.01). The spatial ST difference at J+20 ms discriminated well between the groups, especially when corrected for QRS-magnitudes at rest and heart rate (P less than 0.0005). In short, this pilot study supports previous findings in that changes in amplitude and duration of the QRS complex during exercise discriminated between healthy young males and patients with ischaemic heart disease. Moreover, rapid discriminating changes were seen in the QRS segment during cessation of exercise. These changes deserve attention since they may be of importance for the conflicting results on the diagnostic value of QRS changes during exercise.
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PMID:Ischaemic heart disease and the changes in the QRS and ST segments during exercise: a pilot study with a novel vectorcardiographic system. 158 38


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