The tilting disc of the Björk-Shiley prosthetic valve was recently equipped with a ring-shaped radiopaque marker. Fluoroscopic study became able to demon-strate its movement in detail. Depending on the fact that the prosthetic valve ring and the disc are round and can easy be photographed elliptic in shape by cineradiograph, we originated a new formula to calculate the angle between them.
The length of the major and minor axes of the prosthetic valve ring and the disc and the angle between the minor axes were measured from appropriate projections of cineradiograph of the Björk-Shiley tilting disc valve in vitro. These three values were thrown into our original formula; Φ =cos^-1(sin θ_r sinθ_d cos ψ_dcosθ_r cosθ_d) to calculate the opening or closing angle (φ).
The opening and closing angles were calculated to be 59. 8±1. 30 and 0. 642±0. 649, respectively. The error to the true value, 60 degrees or 0 degree, was within 5%. Reproductivity was also confirmed to be satisfactory.
Therefore, we believe that our method is simple and reliable to estimate the opening and closing angles of the Björk-Shiley tilting disc valve and could be a good non-invasive method for evaluation of the function of this valve in postoperative patients.

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In ordinary techniques and procedures of Kolobow membrane oxygenator with pure oxygen, PaO₂ value was so high and PaCO₂ value gradually increased according to the longer perfusion time in clinical data that pure oxygen gas blood flow ratio was 1.0. Gas transfer performance of Kolobow membrane oxygenator was evaluated with air gas mixture containing about 40% to 60% O₂ in place of pure oxygen in vivo testing. This study showed that proper constitution of arterial blood gas was obtained in spite of long-term perfusion in laboratory and clinical data.
One should be investigated a adequate technique in extracorporeal circulation using the membrane oxygenator under hypothermia in future.

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Fifteen cases out of 166 patients who underwent a pacemaker implantation in our clinic presented pacing failure due to elevated threshold. For this problem, a pacing study was performed on using a temporary catheter electrode connected to an external pacemaker during 10 to 14 days prior to pacemaker implantation. In cases showing a rising tendency in threshold preoperatively, generator of greater output was preferably employed. In some cases presenting a higher threshold than the capacity of the generator, myocardial stimulation technique was helpful than endocardial stimulation.
While, the impedance and the potential after stimulation can provide much valuable information concerning whether the pacing failure is due to an elevated threshold or not. The impedance can express the electrophysiological conditions between the electrodes. The potential after stimulation might be useful to detect a possible existence of some pathological conditions around the electrodes. Actually, when a catheter electrode was floating, the impedance was lower and P. A. S. was higher than usual.

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An intracardiac suction apparatus of the siphonage type and a negative pressure limitting apparatus were developed. An intracardiac suction apparatus is composed of a main tube, an air chamber and two narrow tubes which combine an air chamber with a main tube. A collapsible tube is connected at the lower position of a main tube. A negative pressure limitting apparatus is composed of two syringes which are combined by a flexible tube. The negative pressure which is generated by the vacuum pump is controlled by a negative pressure limitting apparatus. The suction ability of the system is 77ml/sec. The hemolysis by siphonage type apparatus is much less than that by the ordinary roller type apparatus.

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The gas transfer performance and Scanning-Electron-Microscopic findings of Kolobow membrane oxygenator during long-term perfusion have been studied in vivo. During 26 hours perfusion, the dysfunction of membrane oxygenator in blood gas exchange was not observed and few red cells and fibrin films were laid down on the membrane surface on SEM observations.
These findings revealed that Kolobow membrane oxygenators was endurable in long-term perfusion.

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