[Doppler echocardiography determination of the pressure gradient and valve orifice area in mitral valve stenosis]. / Doppler-echokardiographische Bestimmung von Druckgradient und Klappenöffnungsfläche bei Mitralstenose.

Pressure gradient and orifice area of stenosed mitral valves can be determined with Doppler echocardiography using the modified Bernoulli equation and the pressure half-time method, respectively (Figures 1 and 2). There was a close linear correlation between Doppler-echocardiographically determined pressure gradients and valve orifice areas with those obtained by invasive methods. In this study, in 85 patients with mitral stenosis of various severity, the valve orifice areas, as derived by the two methods respectively, correlated well (y = 0.89x + 0.15) with a correlation coefficient r = 0.96 and standard error of the estimate SEE = 0.12 cm2 (Figure 3). The correlation was not influenced by the prevailing cardiac rhythm, ventricular function, left ventricular mass or coexistent mitral or aortic regurgitation (Table 1). Accordingly, the Doppler echocardiographic method also appears applicable in the presence of concomitant mitral and aortic regurgitation which precludes an exact determination of valve orifice area with invasive methods. The Doppler echocardiographic method is currently so well validated that it can be regarded as a reliable noninvasive procedure for determination of the severity of mitral stenosis.

[Applicability of nuclear spin tomography to heart diseases]. / Einsatzmöglichkeiten der Kernspintomographie bei Erkrankungen des Herzens.

Thirty-one patients with abnormalities of the heart and ten controls were examined by ECG-triggered nuclear resonance tomography. All patients had previously been completely investigated. Chamber sizes and mural thickness could be reliably demonstrated and, in addition, it was possible to show areas which could not be easily investigated by echocardiography. Visualisation of the valves was limited, but intra- and para-cardial lesions could be differentiated by a double echo technique. Absence and defects of septa could be shown exactly, as well as accurate demonstration of the relationship of the large vessels to the cardiac chambers.

[Assessment of haemodynamic parameters using non-triggered radioisotope methods (author's transl)]. / Erfassung hämodynamischer Grössen durch ungetriggerte nuklearmedizinische Verfahren.

The minimal transit times (MTTs) are the shortest transport times of a tracer in sequential segments of the heart. The MTTs are measured with a conventional gamma camera, after an i.v. injection of an intravenously retained radiopharmaceutical. Theoretical considerations predict that the MTTs are inversely proportional to the "ejection fraction" of a given segment. An advantage of this method is that the MTTs not only yield information about the function of the left ventricle but also indicate the haemodynamic status of all the other heart segments. The MTT measurement is not susceptible to disturbances related to background correction and ventricle delineation, and is easily performed even under peak exercise conditions. By means of comprehensive data the sensitivity usefullness of this quick and easy procedure are demonstrated.

[In-vivo-examinations of the relative radiosensitivity of hypoxic tumor cells (author's transl)]. / In-vivo-Untersuchungen über die relative Strahlenempfindlichkeit hypoxischer Tumorzellen

The rate of cellular losses of hypoxic respectively euoxic cells of the solid experimental tumor "sarcoma 180" was examined in vivo after irradiations with gamma rays, 15 MeV neutrons, and alpha particles. The tumor cells were labeled in vivo, at first with 125I-UdR and after 50 hours with 131I-UdR. After a further interval of about 20 hours the tumor was irradiated. This method of double labeling makes it possible to determine externally the rates of cellular losses in the labeled zones of tumor cells presenting different partial oxygen pressures. The increase of the rates of cellular losses among the euoxic and hypoxic tumor cells induced by the gamma radiation differs by 2.6; it decreases, however, to 1.5 after injection of nitrofurazone prior to the irradiation. After irradiation with 15 MeV neutrons, a difference of only 1.4 was observed. If the tumors were irradiated internally with alpha particles from the reaction 10B(n,alpha) 7Li, there was no difference between the two rates of cellular losses. As far as the above mentioned kinds of radiation are concerned, the ratios from the increase of the rates of cellular losses induced by radiation are well corresponding to the oxygen enhancement found by other authors during their examinations in vitro.