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Biomedical subjects

N Tuna

Publications and source records attributed to N Tuna.

At least 37 records · Page 2Linked to original sources
PubMed1978

Correlation of electrocardiographic and pathologic findings in healed myocardial infarction.

A correlative study in 50 cases of healed myocardial infarction compared the 12 lead electrocardiogram with pathologic observations. The electrocardiogram was interpreted according to established Minnesota codes with some modifications. The following conclusions were reached: (1) The electrocardiogram underestimates the extent of myocardial infarction. (2) When a healed myocardial infarct at a specific location is recognized with electrocardiographic criteria, it is likely that there are unrecognized infarcts involving other areas of the left ventricle. (3) Infarctions involving the lateral and inferobasal areas are frequently unrecognized. (4) The electrocardiogram is more likely to miss myocardial infarcts in patients with multiple, than in those with single, electrocardiographically diagnosed infarcts. (5) Apical myocardial infarction does not appear to have specific electrocardiographic findings, other than those related to general infarct localization by electrocardiogram, particularly in patients with anteroseptal or anterolateral infarction. (6) Abnormal Q waves, generally thought to indicate transmural myocardial infarction, are frequently found in subendocardial infarction. (7) The simplified electrocardiographic classification of myocardial infarct site (anteroseptal, inferior, anterolateral) used in this study is preferable to more detailed classifications previously suggested by others.

Adult↗
PubMed1977

Influence of population on the classification of ECG-VCG's using linear regression techniques.

This paper describes the influence of different populations on statistical multivariate classification rules and classification results where the word "population" refers only to the frequency of diagnoses to be expected, the so-called prior probabilities. Using linear regression as a multivariate classification technique and six groups consisting of five pathological conditions and normals as test data, it has been shown: (a) That the population influences to a great extent the selection of the best ECG-VCG measurements for the classification rule. (b) That a mismatch of the populations in the learning and test sets can considerably decrease the number of correct classifications. (c) That a certain correction of the mismatch can be achieved when the prior probabilities in the learning and test sets are known, Further, the paper discusses the change of prior probabilities over the years at the Variety Club Heart Hospital in the University of Minnesota and its effect on the performance of the classification algorithm which has been used.

Electrocardiography↗
PubMed1977

Electrocardiographic and vectorcardiographic abnormalities in Fabry's disease.

Fabry's disease has been reported to be associated with ECG abnormalities. Thirty-two patients with this disease followed in the University of Minnesota had ECG's and 15 had VCG's. An abonrmal rhythm was observed in two patients on initial examination and four more developed abnormal rhythm on follow-up examinations. A short PR interval (120 msec. or less) was seen in five patients. Thirteen others had a PR interval that was less than 140 msec. Conduction abnormalities involving the A-V node or His bundle or its branches were present in 22 per cent of the patients, most frequently the intraventricular conduction defects progressing to the right bundle branch block. Atrial or ventricular enlargement was seen in 60 per cent of the patients, left ventricular hypertrophy being the most common. ST-T changes with or without chamber enlargement were seen in 10 patients. One patient had an anterior myocardial infarction pattern on his ECG. Hemizygosity was found to be associated with significantly more abnormalities than heterozygosity. The severity of conduction defects also increased with the duration of the disease process. Vectorcardiography in this study did not provide significant additional information other than that observed on the ECG alone. Since the pathology usually reveals myocardial fibers, conduction system, and blood vessels infiltrated with glycosphingolipid, it is believed that lipid infiltration is responsible for conduction defects, chanber enlargement, and other abnormalities. Although Fabry's disease is rate, it may be amenable to therapy; therefore, recognition of cardiac involvement is important.

Adolescent↗
PubMed1977

Reassessment of the diagnostic value of the vectorcardiogram in cystic fibrosis (correlation with clinical score, pulmonary function tests and echocardiogram).

In 21 children with cystic fibrosis, the vectorcardiogram (VCG) was correlated with various indices of the severity of the disease. The best correlation was found between (1) the azimuth angle of the spatial QRS loop area, representing the rightward and posterior shift of the main electrical forces, and pulmonary function tests (PFT): FEV1 % predicted (r = -0.671, P less than 0.005) and VC% predicted (r = -0.607, P less than 0.005), and (2) the right ventricular anterior wall index measured echocardiographically (r = 0.472, P less than 0.05). More VCG parameters correlated significantly with PFT than with the echocardiogram. This shows the major influence of pulmonary changes on the VCG of those patients. In several subgroups with different clinical scores, the VCG were analyzed and compared to normal limits of age- and sex-matched controls. In this small series, the VCG was a specific but not very sensitive method for predicting the degree of severity of the disease. Echocardiography and vectorcardiography can be considered as two complementary techniques in the evaluation of cystic fibrosis.

Adolescent↗
PubMed1976

Initial vectors of ventricular premature beats and anterior fascicular conduction defects.

Vectorcardiographic studies on ventricular premature beats (VPB'S), occurring in records wherein the sinus beats were associated with an intraventricular conduction defect attributed to anterior fascicular delay or block, did not identify the exact site of a presumed reentry mechanism. The hypothesis that the orientation of the initial vectors of the VPB might reveal either anterograde or retrograde emergence from the anterior fasciulus iwth a reentry PVB was not strongly supported, although one or the other mechanism was compatible with the early vectors of certain VPBs. The VPBs revealed greater angular change on the spatial orientation of sequential early vectors (5--10--15 milliseconds) than occurred in sinus beats. Recurring VPBs, which appeared to casual visual inspection steriotyped in form, showed considerable variation in the orientation of the early vectors, indicating, in the cases studied, that VPBs, in the strictest sense, may be associated with differing initial entrance pathways to the myocardium and thus may be 'multiform'.

Adult↗
PubMed1975

P wave abnormalities in the orthogonal electrocardiogram: Correlation with ventricular overload in pulmonic and aortic valvular heart disease.

The correlation between several P wave measurements form the orthogonal electrocardiogram (SVEC III lead system) extracted by computer analysis and simple hemodynamic parameters related to ventricular dysfunction was studied in two groups of patients. Group I consisted of 32 patients with pulmonic valvular stenosis and intact interventricular septum. There was a significant correlation between electrocardiographic criteria of right atrial overload and the two hemodynamic parameters studied: peak pulmonic systolic pressure gradient and right ventricular end diastolic pressure (r = 0.502, p smaller than 0.005 and r = 0.661, p smaller than 0.001 respectively). Group II consisted of 49 patients with aortic valve disease. In this group, a significant correlation between the electrocardiographic parameters of left atrial overload and the left ventricular end diastolic pressure could be demonstrated only be a multivariate regression analysis (r = 0.630, p smaller than 0.005). The P wave measurements that are well correlated with the ventricular end diastolic pressure can be considered as valuable criteria for atrial enlargement secondary to a decrease of ventricular compliance, such as seen in ventricular hypertrophy, failure or in ventricular constrictive or restrictive diseases. The pathophysiologic mechanisms of the influence of the ventricular overload (dysfunction) on the atrial function and the resulting P wave changes are discussed.

Adolescent↗
PubMed1975

Quantative analysis of the vectorcardiogram in obesity. The effects of weight reduction.

Vectorcardiograms (VCG) recorded in 37 subjects with marked chronic EXOGENOUS OBESITY (AVERAGE WEIGHT: 285 LBS.) WERE COMPARED before and after a significant weight reduction (average weight loss: 86 lbs). They were also compared with the VCGs of 293 age and sex matched controls with normal body weight. The SVEC III corrected orthogonal lead system was used, and out of several hundred vectorcardiographic measurements obtained by computer processing, 59 measurements representing various scalar, planar and spatial voltage and angular measurements were selected for study and comparisons. No significant differences were found between the measurements of obese subjects and those of the controls. Of 59 VCG measurements, 13 showed significant differences after weight reduction (paired t test) although they remained within the range of normal controls. There was a trend toward decrease of P and QRS amplitudes after weight reduction. There were no significant changes in the angular measurements. Although they are statistically significant these changes in voltage are too small to be detected in clinical vectorcardiography. The possible decrease of a preexisting myocardial hypertrophy superimposed onto the changes in the anatomy of the thorax might explain the effects of weight reduction. In general the reproducibility of VCG measurements obtained by the SVEC III system was greater than that reported in day-to-day operation with the Frank system in normal subjects.

Adipose Tissue↗
PubMed1975

Regional Myocardial Blood Flow Measurement in the Evaluation of Patients with Coronary Artery Disease.

Myocardial imaging with 133-Xe and a gamma camera was employed to evaluate total and regional myocardial blood flow. The technique detected vasodilatation after injection of papaverine or diatrizoate. Contrast medium caused transient vasodilatation with return to baseline flow within five minutes. Myocardial tissue flow tended to decrease as coronary artery stenosis became more severe. There was overlap of flow measurements in patients with and without coronary artery disease. Coronary flow measurements made at rest are not considered to be an essential clinical tool. gpreater diagnostic benefit is obtained from the scintigram which distinguishes between akinesia caused by ischemia and akinesia due to extensive scarring.

Contrast Media↗
PubMed1975

Regional myocardial blood flow measurements before and after coronary bypass surgery. A preliminary report.

Myocardial blood flow in 16 patients before and after coronary bypass surgery in conjunction with coronary angiography, left ventricular function measurement, and graded exercise test. Radioactive 133-Xe was injected into the coronary artery or bypass graft and the washout was recorded by an Anger camera. Myocardial blood flow increased in 11 out of 14 patients and decreased in three patients. The average flow was 55 (plus or minus 6) preoperatively and 96 (plus or minus 10) ml 100 g/min postoperatively. Increase of blood flow occurred in both the bypassed left anterior descending coronary artery (LAD) region and the nonbypassed left circumflex coronary artery (LCIR) region. The postoperative flow increase and the absolute postoperative flow values are higher with saphenous vein than with mammary artery grafts. Statistically significant correlation is not found between myocardial blood flow changes and exerice tolerance. The volume measurements (end diastolic volume, stroke volume, ejection fraction) remained unchanged.

Adult↗
PubMed1968

Correlation of vectorcardiogram and electrocardiogram with coronary arteriogram.

One hundred patients with suspected coronary heart disease were studied by vectorcardiography (VCG), electrocardiography (ECG), and coronary arteriography. Twenty-eight patients had VCG evidence of anterior infarction; 26 of this group had severe narrowing or obstruction of the left anterior descending branch. Five did not have anterior infarction by ECG. Twenty-seven patients had VCG evidence of diaphragmatic infarction; 25 of this group had severe narrowing of the right coronary artery or the left circumflex branch or both. Six of the 27 did not have ECG evidence of diaphragmatic infarction. Twelve patients had VCG evidence of posterior infarction whereas it was detected by ECG in only two. Only six of the 12, however, had severe narrowing of the nutrient arteries to the posterobasal part of the myocardium. Thirteen patients with infarction had severe narrowing but not total obstruction of a coronary artery. On the other hand, 15 patients had total obstruction of a major coronary vessel without actual infarction.

Adult↗