Measurement of Pressures in Man by Cardiac Catheters

Relationships between artefacts in recorded intracardiac pulses and the dynamic response and susceptibility of catheter-manometer systems to artefacts caused by motion of the catheter were investigated. Sine-wave motions of the catheter, resembling motion frequently seen when the catheter is in the pulmonary artery, produce sine-wave pressure variations with peak-to-peak amplitudes of 10 mm. Hg. Square-wave motions (impacts) produce high-frequency pressure variations, greatest (10 to 200 mm. Hg) when directed along the axis and much less when perpendicular to the axis of the catheter. High-fidelity records of pressure by conventional cardiac catheter-manometer systems are most unlikely when such catheters are threaded through the beating heart.