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Biomedical subjects

S Walton

Publications and source records attributed to S Walton.

At least 109 records · Page 6Linked to original sources
PubMed1984

Patterns of ventricular contraction in patients with conduction abnormality studied by radionuclide angiocardiography.

The phase image generated by radionuclide angiocardiography illustrates the regional timing of ventricular wall motion. In this study the phase image was used to investigate the patterns of ventricular contraction in 103 subjects with either normal hearts or a conduction abnormality. In 38 normal subjects the right ventricle contracted on average 7 ms after the left, and the last region to contract was the right ventricular outflow tract. In 15 subjects with left bundle branch block the left ventricle contracted 69 ms after the right, contraction spreading from the septum to the lateral wall. In 12 subjects with right bundle branch block right ventricular contraction occurred 54 ms after the left. In 11 subjects with right bundle branch block and left anterior fascicular block both right and left ventricular contraction were delayed, the right more so than the left. In three of five subjects with the Wolff-Parkinson-White syndrome and four with frequent ventricular extrasystoles areas of early contraction corresponded to areas of early depolarisation. It is concluded that ventricular contraction can be studied non-invasively and follows a pattern to be expected from the pattern of electrical depolarisation.

Cardiac Complexes, Premature↗
PubMed1983

Regional variation of left ventricular transit time in normal ventricles and those with abnormalities of contraction.

Thirty-three subjects were studied by first pass radionuclide angiography. The extrapolated monoexponential tracer washout slopes from septal, lateral, and apical segments of the left ventricle were measured. In 13 subjects with normal left ventricles, as assessed by ejection fraction estimation and phase analysis, there was no difference between septal and lateral segments but, in each case, apical washout was significantly prolonged. In 20 subjects with abnormal ventricles washouts were, in general, slower than those of the normal ventricles. Apical washout was still the slowest but the difference between base and apex was less pronounced. In contrast to the normal ventricles, differences appeared between septal and lateral segments. The left ventricle is a poor mixing chamber. Pools of relative stasis exist at the apex of both normal and abnormal ventricles and within the body of the chamber in the latter.

Coronary Circulation↗
PubMed1983

Variation in mast cell numbers in psoriasis and lichen planus: comparisons with normal skin.

This study has examined the influence of age, sex, and site on the numbers of mast cells in normal human skin from 60 healthy Indian volunteers. 5-microns-thick paraffin-embedded sections were stained with 0.001% toluidine blue and the mean number of mast cells per mm3 estimated. Multivariate analysis of variance revealed significant effects of age, site and sex upon mast cell numbers with greater numbers in the facial skin of young females compared with arm skin of young patients of both sexes and older females. Mast cell numbers were also significantly higher in both involved and uninvolved skin of patients with psoriasis in contrast with increased numbers in involved skin only, observed in lichen planus. This is the first report of mast cell density in Indian Caucasian skin.

Adult↗
PubMed1982

Phase analysis of the first pass radionuclide angiocardiogram.

Fifty-two subjects with suspected coronary artery disease were studied by first pass radionuclide angiocardiography using a single crystal gamma camera. Phase analysis, a new technique which can detect ventricular regions with abnormal emptying patterns, was applied to the resulting left ventricular radionuclide angiocardiograms. Eighteen turned out be normal and in these subjects the variation of phase values in each of eight ventricular segments was established. Thirty-four had coronary artery disease. By comparison with the normal subjects, 21 had at least one segment with an abnormally high phase value. Such high values were associated with low values of ejection fraction, as determined by a radionuclide technique, total occlusion of a major coronary artery and significant wall motion abnormalities on the radiographic ventriculogram. A comparison between phase analysis and wall motion on a regional basis disclosed progressively high phase values with increasing severity of wall motion abnormality. Particularly high values were found in association with ventricular aneurysm. Phase analysis of first pass radionuclide angiocardiograms is a valid method for the detection of regional abnormalities of ventricular contraction in coronary artery disease.

Adult↗
PubMed1981

Phasic abnormalities of left ventricular emptying in coronary artery disease.

Seventy subjects with suspected coronary artery disease were studied by radionuclide angiocardiography. Delayed or paradoxically emptying regions of the left ventricle were detected by a relatively new nuclear technique--phase imaging. The results were assessed in the light of cardiac catheterisation findings. Compared with 19 normals, regions with abnormally high phase (and therefore late emptying) were found in 42 of 61 subjects with coronary disease. High phase values were associated with total occlusion of a major coronary artery, low ejection fraction, and extensive wall motion abnormalities. The phase image greatly facilitated the calculation of contractile segment ejection fraction in 14 cases of left ventricular aneurysm. In three of these postoperative left ventricular ejection fraction agreed closely with preoperative contractile segment ejection fraction and there was a distinct improvement in the phase image after aneurysmectomy.

Adult↗
PubMed1980

Regional left ventricular wall motion from first-pass radionuclide angiocardiography using an Anger camera. Experimental and clinical study.

Experimental studies with a balloon phantom, and clinical studies were performed to evaluate first-pass radionuclide angiocardiography using a gamma camera in the assessment of regional wall motion. The phantom studies showed that choice of isocount contour was not critical in edge detection. Adequate count densities could be achieved, but only at the expense of temporal resolution. The clinical studies disclosed a good correlation with radiography in normal subjects and those with diffuse ventricular disease but a poor correlation in subjects with localised abnormalities of wall motion.

Cineangiography↗
PubMed1979

Holistic medicine.

Explore the source record for details and available documents.

Delivery of Health Care↗
PubMed1979

Study of right ventricular function in ischaemic heart disease using radionuclide angiocardiography.

A technique for the estimation of LVEF from first passage radionuclide angiocardiography was adapted to provide estimates of RVEF. In 17 subjects with no history of cardiovascular disease mean LVEF was 0.71 +/- 0.08 and mean RVEF 0.65 +/- 0.08. Mean values for 15 subjects with coronary artery disease but no previous history of myocardial infarction were 0.66 +/- 0.10 for LVEF and 0.65 +/- 0.08 for RVEF. Depressed ejection fractions were found after acute myocardial infarction. LVEF was lower after anterior (0.43 +/- 0.06) than inferior (0.51 +/- 0.10) infarction. RVEF was normal in the majority of subjects with anterior infarction (0.58 +/- 0.10) but was depressed after inferior infarction (0.50 +/- 0.05). Similar, although less marked, results were found in a group of subjects with old myocardial infarction.

Adult↗
PubMed1978

Use of 129caesium, 99Tcm stannous pyrophosphate, and a combination of the two in the assessment of myocardial infarction.

Acutely damaged myocardium was shown in 103 patients with suspected acute myocardial infarction using 99Tcm pyp. A significant incidence of false positive and false negative results occurred, 'true' results being defined by standard clinical, electrocardiographic, and enzyme criteria. Localisation of infarction compared reasonably well with standard electrocardiographic criteria but more frequently suggested true posterior involvement. Serial estimates of infarct size may be of value in the recognition of infarct extension during the acute phase. Viable perfused myocardium was shown in 63 patients with a variety of cardiac disorders using 129Cs. The technique gives a reliable indication of anterior infarction but tends to underestimate inferior infarction. There was good correlation with the electrocardiogram with regard to localisation and extent of infarction. Nineteen patients received both isotopes and were included in each of the above groups. The combination permits further assessment of equivocal results Furthermore as 129Cs demonstrates both previous and recent infarction and 99Tcm pyp accumulates only in acutely damaged myocardium it was possible to estimate the extent of previous and recent myocardial damage.

Adult↗