Search PubMed⌕ Search

Biomedical subjects

A Neumann

Publications and source records attributed to A Neumann.

At least 145 records · Page 8Linked to original sources
PubMed1984

Left ventricular end-systolic wall stress-velocity of fiber shortening relation: a load-independent index of myocardial contractility.

The velocity of circumferential fiber shortening (Vcf) is an index of myocardial performance which, although sensitive to contractile state, has limited usefulness because of its dependence on left ventricular loading conditions. This study investigated the degree and velocity of left ventricular fiber shortening as it relates to wall stress in an attempt to develop an index of contractility that is independent of preload and heart rate while incorporating afterload. Studies were performed in 78 normal subjects using M-mode echocardiography, phonocardiography and indirect carotid pulse tracings under baseline conditions. In addition, studies were performed on 25 subjects during afterload augmentation with methoxamine, 8 subjects before and during afterload challenge after increased preload with dextran and 7 subjects with enhanced left ventricular contractility with dobutamine. The relation of end-systolic stress to the velocity of fiber shortening and to the rate-corrected velocity of shortening (corrected by normalization to an RR interval of 1) was inversely linear with correlation coefficients of -0.72 and -0.84, respectively. Alterations in afterload, preload or a combination of the two did not significantly affect the end-systolic wall stress/rate-corrected velocity of shortening relation, whereas during inotropic stimulation, the values were higher, with 94% of the data points above the normal range. Age did not appear to affect the range of normal values for this index. In contrast, the end-systolic wall stress/fractional shortening relation was not independent of preload status, responding in a manner similar to that seen with a positive inotropic intervention. Thus, the velocity of circumferential fiber shortening normalized for heart rate is inversely related to end-systolic wall stress in a linear fashion. Accurate quantitation can be performed by noninvasive means and a range of normal values determined. This index is a sensitive measure of contractile state that is independent of preload, normalized for heart rate and incorporates afterload. In contrast, the end-systolic wall stress/fractional shortening relation is dependent on end-diastolic fiber length in the range of physiologically relevant changes in preload.

Adolescent↗
PubMed1984

[Brain tumor removal with an ultrasound aspirator].

A report is given on the application of an ultrasound aspirator for the removal of cerebral tumours. After the description of physical and surgical fundamentals, a report is given on the respective patients. Then hazards an advantages are described as far as they can be summarized already today.

Brain Neoplasms↗
PubMed1984

[Fundamental studies of ultrasonic surgery. 5. Ultrasonically forced polymerization of Ligament-Fimomed in joining biological tissue].

About basis investigations to the mode of action, the energy transformation, and to the polymerization heat of Ligament-Fimomed adhesive is informed over the ultrasonic osteosynthesis. A prompt activation of the monomeric tissue adhesive is attained at the contact region with the osseous tissue by means of low frequency power ultrasound. The mechanism of the connecting formation and characteristic temperature-time course are shown.

Enbucrilate↗
PubMed1983

Quantitative computer-assisted analysis of left ventricular wall thickening and motion by 2-dimensional echocardiography in acute myocardial infarction.

Quantitative regional wall motion analyses of 2-dimensional echocardiograms (2-D echo) have usually focused on large arcs (greater than 45 degrees) of the left ventricular (LV) perimeter rather than on small LV zones. Few studies have assessed changes in wall thickness. To determine normal ranges of regional LV function, the endocardial and epicardial contours of short-axis 2-D echoes obtained at the papillary muscle level of 10 normal subjects were manually traced. Then, 15 patients with acute myocardial infarction (MI) were studied, comparing their contours at admission with ranges determined from the normal subjects. In all patients with MI, 2-D echoes located abnormal wall motion involving at least the region identified as abnormal by the electrocardiogram and often extending into adjacent regions. All 9 patients with transmural MI had either decreased wall thickening or abnormal endocardial wall motion; all except 1 had focal thinning in the region of the MI. Of the 6 patients with nontransmural MI, 2 had abnormal endocardial wall motion, and all had decreased wall thickening. Evaluating regional wall motion at multiple points around the LV circumference should permit more precise delineation of LV function in health and disease than has been heretofore possible.

Adult↗
PubMed1983

Quantitative analysis of left ventricular wall motion and thickness using two-dimensional echocardiography.

The real time two-dimensional ultrasonic imaging of the left ventricle made possible segmental echocardiographic measurements of wall motion and thickening and thinning. The underlying hypothesis is that measurements of regional wall motion could quantify the extent of myocardial ischemia and infarction; the method could be used as a truly non-invasive tool to assess the severity of damage from infarction and the effects of interventions designed to limit infarcts. The method is operator interactive. Each patient's data could be compared with data for a normal group. The selection criteria for the normal patients have been described. The confidence region of the normal group and the effect of averaging over three tracings for three heartbeats have been computed. Technical difficulties inherent in the method and possible improvements are discussed.

Computers↗
PubMed1982

Sensitivity of end-systolic pressure-dimension and pressure-volume relations to the inotropic state in humans.

The value for the slope of the left ventricular (LV) end-systolic pressure-dimension and pressure-volume relations has been proposed as a quantitative measure of the LV inotropic state. This measure of LV inotropic state is attractive because it is independent of preload and incorporates afterload. To investigate the sensitivity of the slope of these relations to alterations in contractile state, 10 normal subjects were studied using M-mode echocardiographic, phonocardiographic and indirect carotid pulse recordings during infusion of methoxamine to alter end-systolic pressure and during infusion of dobutamine (5 micrograms/kg/min) to increase LV inotropic state. Heart rate was maintained within a narrow range for each subject. End-systolic volume was calculated from end-systolic echocardiographic dimension by standard methods. End-systolic pressure was estimated from the dicrotic notch pressure determined from a calibrated carotid pulse recording; peak systolic pressure was also measured. Regardless of the method of approximating end-systolic pressure, the positive inotropic intervention caused a leftward shift in the end-systolic pressure-dimension and pressure-volume lines. With the dobutamine infusion, the value for the slope of the end-systolic pressure-dimension relation increased by 25% (range 16-46%, p less than 0.001), while the slope of the end-systolic pressure-volume relation increased by 55% (range 37-85%, p less than 0.001). In all cases, the curves were linear and became steeper with the positive inotropic intervention. In contrast, the value of the slope of the peak systolic pressure-end-systolic dimension relation showed a variable response to the dobutamine infusion (mean change 13%, range -77% to 73%; NS). Although the position of the peak systolic pressure-end-systolic dimension curve is consistently shifted with an alteration in inotropic state, the values of the slope of these curves are not reliable indicators of change in LV contractility. The values for the slope of the line relating end-systolic pressure (estimated by dicrotic notch pressure) to end-systolic dimension or volume, however, are highly sensitive to a change in inotropic state in human subjects.

Adult↗
PubMed1981

[Basic studies on ultrasonic surgery. I. Principles, status and perspectives of ultrasonic surgery].

The ultrasonic power with regard to its medical use for resection, treatment, and joining of soft and hard biologic tissues is investigated after the formation of the ultrasonic diagnostics and therapy. The situation of the ultrasonic surgery as an unconventional method for the ingenious complementation of tested operative techniques is valued after the representation of the mode of operation and the present equipment. The trend of development and prospective problems of the research are deduced from them.

Amputation Stumps↗
PubMed1980

[Studies of the morphological and morphometrical changes in the rat nephron after unilateral ureteral ligation (author's transl)].

The influence of unilateral ureteral ligation in the rat nephron has been morphometrically analysed. The glomeruli show no significant differences compared with the control groups. The lumen of the tubulus rectus I increases significantly, but irregularly, after the 6th day of ureter ligation. The brush border is mostly destroyed after the 8th day. The tubulus rectus II changes only very little during this period. At the beginning of the ligation the lumen dilates, and at the end of the experiment the tubulus becomes normalised. The most important changes have been seen on the collecting tubules. As a consequence of increased intratubular pressure the lumina continuously dilate.

Animals↗
PubMed1979

[The supply of wild ruminants with major and trace elements. 2. The manganese content of winter grazing and the manganese status of red deer, fallow deer, roes and mouflons].

The winter grazing of wild ruminants on mantles of slate waste in the Harz mountains and in Gera county were richest in Mn whereas those on mantles of granite waste in the Erzgebirge were poorest. The flora of the shell-limestone, keuper and loess areas contains much less Mn than that of those acid habitats. The Mn-requirement of the wild ruminants grazing in the forests is met however, since bilberry plants (2,080 mg/kg), spruce twigs (984 mg/kg), spruce bark (827 mg/kg), oak twigs (791 mg/kg) and heather (754 mg/kg dry matter) in addition to many other plant species store extremely high amounts of Mn. Solely sallow twigs were poor in Mn (28 mg/kg). Based on 601 samples examined, the Mn supply of wild ruminants is extensively described. The rumen content reflected the plentiful Mn-supply of the wild ruminants living in forests (greater than 400 mg/kg) and the far worse one of field roes, particularly in Mn-deficiency areas for domesticated ruminants (mantle of shell-limestone waste 37 mg Mn/kg dry matter of rumen content). The indicator organs of the Mn-status (liver, covering hair, kidneys) verify the statements made concerning red deer, fallow deer and mouflons, of which a total of 170 head from 14 biotopes were examined. An Mn-deficit of field roes in Mn-deficiency habitats in winter cannot completely be excluded. Mouflons have not yet been able to adapt themselves to the excessive Mn-supply of the acid forest habitats in Central Europe. They stored significantly higher amounts of Mn in liver, covering hair, kidneys, cerebrum and ribs than the other wild ruminants and sheep and cattle. The normal Mn-content of the liver and the cerebrum of red deer, fallow deer and roes corresponds to that of sheep and cattle. Roes and fallow deer have winter covering hair poor in Mn (less than 4.0 mg/kg) in comparison to sheep and cattle.

Animal Nutritional Physiological Phenomena↗
PubMed1979

Determination of right atrial and right ventricular size by two-dimensional echocardiography.

No data are available on determining right atrial and right ventricular size by two-dimensional echocardiography. We performed two-dimensional echocardiograms on eight human right-heart casts obtained at autopsy and on 50 patients who underwent complete left- and right-heart catheterization. Measurement of individual dimensions of the long and short axes of the right atrium and ventricle from right heart casts closely correlated with the volume of these structures as determined by water displacement. Further, individual dimensions by cross-sectional echo correlated well with actual casts dimensions. Subsequently, echocardiographic measurements of right atrial and ventricular long and short axes were obtained in the apical four-chambered view in a group of normals and compared with a group of patients with right ventricular volume overload states. Mean values for right atrial short-axis and long-axis measurements were greater in right ventricular volume overload patients than in normals: 6.5 +/- 0.3 vs 3.6 +/- 0.1 cm, and 6.0 +/- 0.3 vs 4.2 +/- 0.1 cm, respectively (both p less than 0.001). In addition, measurements of both individual dimensions as well as planed area of the right ventricle were greater in right ventricular volume overload patients than in normals: maximal short axis 6.1 +/- 0.3 vs 3.5 +/- 0.2 cm, mid-short axis 6.1 %/- 0.4 vs 2.8 +/- 0.2 cm, and area 40 +/- 2.6 vs 18 +/- 1.2 cm2 (all p less than 0.001). There were no differences in right ventricular long-axis measurement. Two-dimensional echocardiography provided better separation of normals from right ventricular volume overload patients than did M-mode techniques. Thus, two-dimensional echocardiography, with the apical four-chambered view, enables accurate visualization of the right atrium and ventricle in almost all patients. Futher, measurements of right atrial and right ventricular size by two-dimensional echocardiography readily distinguish normal patients from those with right ventricular volume overload.

Adolescent↗