1977 年 18 巻 5 号 p. 664-678
The purposes of this study about the catheter-manometer systems are two-fold. One is to assess the effects of temperature change and saline flushing on the frequency response of the catheter-manometer systems. The second is to show the method of obtaining the maximum performance from conventional catheter-manometer systems by using the equalizing network. The temperature change from 25° C to 37°C affected little the frequency response of them. However, the saline flushing affected them considerably but they were stabilized after they were flushed frequently with saline or after vibrating pressure was applied to them for 2 or 3 min. These results suggest that it is possible to prevent the change of the frequency response of the catheter-manometer systems when used clinically.
Then, the equalizing network was made in order to equalize the frequency response of the catheter-manometer systems. By using this network, up to 1.3 times the undamped natural frequency, the amplitude characteristics of the catheter-manometer systems became almost flat within about 10% of error and the phase shift became directly proportional to the frequency within 10% or less of error. In experiments with dogs, both the left ventricular pressure and their first derivative wave forms from this network were highly similar to those from standard systems. Seventy-three left ventricular tracings obtained with 10 catheter-manometer systems whose natural frequencies ranged from 28.9 to 69Hz were compensated by using this network. The correlation coefficient of the peak LVP was 0.995 and that of max dp/dt was 0.991. In clinical use, the distortion of LVP tracings obtained with the catheter-manometer system was reduced by this network. The compensated waves were similar to those obtained with the catheter-tip manometer and had few motion artefacts.
