Measurements of intravascular pressure fluctuations and blood flow turbulence were made in six calves in close vicinity of a surgically induced pulmonic stenosis. The experiments were carried out in three series: Series I measurements were made intraoperatively in open-chest calves with 40% and 60% stenosis and varying heart rates due to Isoproterenol infusions. Series II measurements were performed at three different times during 112 days after recovery. Series III experiments were performed 159.2 ± 5.8 days following the initial surgery; the chest was reopened. Spectral analysis of the simultaneously measured pressure and flow fluctuations showed a range of −53 power slope in the flow energy spectra which break into −103 power slope at approximately 100 Hz. The pressure energy in the same frequency range increased sharply. Based on the data, the transformation of energy flow fluctuations to pressure fluctuations is discussed. The variations of intravascular pressure energy in axial positions with respect to the stenosis are presented.
