FOURIER解析による,肺動脈圧波のPEAKING現象の研究
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概要
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The systolic and pulse pressures tend to increase with steeping of the systolic wave toward the periphery of the large and long arteries; indeed, the femoral puls pressure is usually considerably greater than the aortic (Hurthle's peaking phenomenon, Fig. 1). Following several theories were presented for explanation of this phenomenon; (1) : the reflexion theory of pressure wave, (2) : elevation of hydrostatic pressure due to deceleration of flow velocity in the periphery (application of Bernoulli's theory), (3) : the water hammer theory and (4) : the theory of active driving force of arteries. In 1961, Nakamura, one of our collaborators, confirmed the existance of the peaking phenomenon in the pulmonary circuit, of which hemodynamic condition differs considerably from that in the systemic circulation. The pulmonary arterial pressure waves in this paper were recorded at the periphery P, branching B, and stem S (Fig, 2). A change rate (%) of the pressure at B and P to that at S (Fig. 7) revealed that the peaking phenomenon was occured more often at B regarding sistolic and pulse pressures than at P. It may be noteworthy from the point of hemodynamic view that the peaking phenomenon was also observed on diastolic and mean pressures in fairly large number of the cases. No definite relation was noted between the occurrence of the peaking phenomenon and blood pressure level, cardiac output or pulmonary vascular resistances (Fig. 8-14). Corresponding to RR interval of ecg simultaneously recorded, the pressure wave of one cardiac cycle was divided into 36 equal parts (Fig. 3). The Fourier analysis was performed on them by use of the electro digital computer HIPAC 103 (HITACHI). The results were obtained on the amplitude of harmonics and phase angle at the starting point t = 0. The amplitude of most of the harmonics was increased when the peaking phenomenon was noted on systolic pulmonary arterial pressure. This is quite logical, since the pulse pressure usually became larger in such a case. However, through examination on each case, disclosed that the incidence of the peaking phenomenon was not always in proportion to the increase in amplitudes of harmonics; accordingly the peaking phenomenon is not simply resulted from the increase in amplitudes alone. The phase angles, did not show any uniform change. Since the pressure pulse travels from the central artery to the peripheral arteries, it may be expected that appearance of the pulse wave shifts towards the right hand, from the reference point of R in ecg. Thus, the phase angles may be expected to be smaller as the pressure wave travels to the periphery. As the matter of fact, the Fourier analysis disclosed that the shift of harmonics may occur in the positive direction, namely, the right direction, or remain unmoved, or even in the negative direction. Investigating these pressure pulses which contain a lot of harmonics shifting to the negative direction (Fig. 22), the original pressure waves were found also oscillating in the negative direction (Fig. 23). The small types of Fig. 23 indicate the positions of the maxima of these harmonics corresponding to their numbers. When the peaking phenomenon existed, the maximum points of the harmonics around the crests of the main deflexion tended to converse together (KT ; S-B), while this convergence occasionally could not be seen when the peaking phenomenon was missed (Fig. 26). Further observations indicated that there may be three possibilities of causing the peaking phenomenon, .namely, increase in amplitude, convergence of maximum points of harmonics around the main crest of pressure wave and the combination of both, as well as the possibility of damping from their cancellation. As a cause of non-uniform change in amplitudes and phase angles of harmonics, effects of reflexion waves may be considered. Depending on the resultant of incident and reflexion waves, amplitudes may become larger or smaller than those of the incident wave. Moreover, phase angles may also shift to positive or negative direction. However, in some cases the shift of harmonics to the negative direction was too large to be explained by the reflexion wave theory. It may be difficult to suppose that the pressure oscillation within arteries is fully attributed to the input force from the heart, for a backflow will occur near the roots of central arteries (aortic and probably pulmonary) at the very beginning of the diastole. Therefore, the changes in arterial pressure pulse, especially the peaking phenomenon, may be resulted not only from the reflexion wave, but also from the active, more or less periodic force of arteries themselves.
- 千葉大学の論文
- 1966-01-28