Left ventricular pressure (LVP), volume (LVV) and length (LVL) were calculated from biphane cineradiographs at 270 frames/sec. A computer datareduction system provided rapid calculation of LVV using numerical integration (Simpson's rule). X-ray distortion errors in LVL and LVV were also corrected with the computer program. LVP was recorded directly on the cine film. The discrete samples at 270 frames/sec were used to construct continuous curves of each parameter throughout the cardiac cycle. Fourier analysis was then applied to the data to obtain frequency spectrum and signal energy spectrum for each curve. From 75 to 35 of the signal was found between 0 and 15 Hz for pressure, 0 and 5 Hz for volume length, 99 of signal energy is contained in the same frequency bands. The low frequency characteristics of these signals indicate that film speeds of 60 frames/sec are more than adequate for reconstruction of continuous curves from discrete samples calculated from cine frames.
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