Frequency Content of Intravascular and Intracardiac Pressures and Their Time Derivatives

The purpose of this study was to determine the frequency content of intravascular pressures and their time derivatives. Pressures, recorded using catheter-tip manometers in patients undergoing diagnostic cardiac catheterization, were amplified, filtered (100 Hz) to minimize aliasing errors, and then converted to digital format at 200 samples/sec. After examination of the waveform to exclude obvious artefact, it was analyzed using a Fourier transform and then resynthesized using a decreasing number of harmonics. Peak dp/dt of both the original and resynthesized waveforms was computed until marked differences were observed.