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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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.