Biomedical subjects
Publications and source records attributed to H A Richter.
A case of double-compartment hydrocephalus in an adult is presented. Although this entity is infrequently noted in children, it is diagnosed even more rarely in the adult population. A discussion of the spectrum of abnormal cerebrospinal fluid dynamics of the 4th ventricle and treatment options are presented.
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Large tumors of the paranasal sinuses can be removed thoroughly with a craniofacial approach that provides for good visualization. With this approach, some tumors previously considered inoperable may be removed and in some cases cured. We report three cases of tumors managed by means of a craniofacial procedure. One case involved an extensive inverting papilloma of the ethmoid sinus that invaded the orbit and coursed over the globe around the optic nerve. The second patient had a large squamous cell carcinoma of the paranasal sinuses that involved the cribriform plate, dura, and a portion of frontal lobe. The third case involved a meningioma that invaded the sphenoid wing, orbit, pterygomaxillary space, and infratemporal fossa. The craniofacial surgical technique and adjunctive therapies are discussed.
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For right ventricular volume determination a new method was developed that took into account right ventricular imaging by apical two-dimensional echocardiography in the four- and two-chamber views. Right ventricular volume was calculated by subtraction of the partial volume of the left ventricle and interventricular septum from the total heart volume of the right and left ventricles including the interventricular septum. Accuracy of the subtraction method was evaluated in isolated human hearts by two-dimensional echocardiography and radiography. Regression analysis indicated that for both the echocardiographic and radiologic procedures, the subtraction method gave the best correlation with the right ventricular filling volume. The correlation coefficients obtained using the echocardiographic procedure were 0.964, 0.848, and 0.851 for the subtraction method, pyramid method, and Simpson's rule method, respectively. For the radiographic procedure, these values were 0.946, 0.860, and 0.872. Percentage difference calculations indicated that the subtraction method systematically underestimated (-7.4%) the filling volume in the echocardiographic procedure, but this was not seen with the radiologic procedures. The random error associated with the subtraction method was only half (10.5%, 13.9%) of that seen with the other two methods in both the echocardiographic and radiological procedures. These results indicate that right ventricular volume determination by the subtraction method seems to be suitable for apical two-dimensional echocardiography and is more accurate than the pyramid method and Simpson's rule method.
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In order to measure the flow-dynamical effect of arteriosclerotic changes of the vessel wall we determined volume elasticity E' and modulus of elasticity of 53 human aortae in a static p-V-test as other authors did, too. The p-V-curves are normalized to the aortic basic volume Vo, so that we could determine the haemodynamic effect of arteriosclerosis immediately from E' and. Diameter, length, and, accordingly, the basic volume of the aorta without prestressing increase significantly in aortae with severe arteriosclerosis in comparison to those without sclerosis. The volume elasticity E' as a function of the static aortic pressure has a minimum within physiological pressure range and changes into a linear function when arteriosclerosis increases. The modulus of elasticity of a normal aorta remains constant within a pressure range of 20 to 100 mm Hg and it shows a linear increase at higher pressure. The differences between Vo, E' and of aortae with and without severe arteriosclerosis, however, are highly significant.
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The irregularity and complexity of the right ventricle is the reason why no accurate method for right ventricular volume determination exists. A new method for right ventricular volume determination particularly for two-dimensional echocardiography was developed-it is called subtraction method-and was compared with the pyramid and Simpson's methods. The partial volume of the left ventricle and septum was subtracted from total volume of right and left ventricle including interventricular septum. Thus right ventricular volume resulted. Total and partial volume were computer-assisted calculated by use of biplane methods, preferably Simpson's rule. The method was proved with thinwall silicon-rubber model hearts of the left and right ventricle. Two orthogonal planes in the long-axis were filmed by radiography or scanned in a water bath by two-dimensional echocardiography equivalent to RAO and LAO-projections of cineangiocardiograms or to four- and two-chamber views of apical two-dimensional echocardiograms. For calculation of the major axes of the elliptical sections, summed up by Simpson's rule, they were derived from the LAO-projection and the four-chamber view, respectively, the minor axis approximated from the RAO-projection and the two-chamber view. For comparison of direct-measured volume and two-dimensional echocardiographically determined volume, regression equation was given by y = 1.01 x -3.2, correlation-coefficient, r = 0.977, and standard error of estimate (SEE) +/- 10.5 ml. For radiography, regression equation was y = 0.909 x + 13.3,r = 0.983, SEE = +/- 8.0 ml. For pyramid method and Simpson's rule, higher standard errors and lower correlation coefficients were found. Between radiography and two-dimensional echocardiography a mean difference of 4.3 +/- 13.2 ml, using subtraction method, and -10.2 +/- 22.9 ml, using pyramid method, as well as -0,6 +/- 18.5 ml, using Simpson's rule, were calculated for right ventricular volume measurements. Differences were not significant. The subtraction method seems to be useful for calculation of right ventricular volume by radiography as well as two-dimensional echocardiography. Further studies in isolated hearts and patients are necessary for final judgment of the accuracy of this new method.
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Etiology and pathogenesis of empty cella syndrome remains undetermined in some cases (primary or idiopathic type), while in others it is related to treatment of pituitary and parasellar disease (secondary type). Ten patients with empty sellae, secondary to treatment of pituitary adenomas (five cases), granulomas (three cases), craniopharyngioma (one case), and optic glioma (one case) are presented. Pathogenesis of empty sella is discussed and the importance of neuroradiologic evaluation of this syndrome is stressed.
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With the described circulation simulator it is possible to simulate physiological values of pulse frequency, filling volume and pressure. Bioprostheses with pathological changes can be investigated in vitro under normal and under specific pathological in vivo circulation conditions. The criteria of classification of the effectiveness of bioprostheses are reflux volume, VR, insufficiency, I and maximal orifice area, A. As a result of the definition of insufficiency, even intact bioprostheses show insufficiency with regard to the closing volume. While the effectiveness of perforated bioprostheses can be clearly demonstrated by reflux volume and insufficiency, the regurgitation of a stenosed valve gives no meaningful statement as to its effectiveness. In this case, the orifice area, A, is a suitable criterion of the classification of effectiveness.