Influence of transmural pressure on retrograde pressure pulse transmission velocity in the canine superior vena cava.

The influence of intrathoracic and intraluminal pressure on venous pressure pulse propagation velocity in the superior vena cava was investigated in acute canine experiments. The propagation velocity of distinct points of the venous pressure curve was measured under different conditions of preload, during expiratory and inspiratory apnea and during positive-negative pressure respiration. Under control conditions transmission velocities varied from 1.07 m/s to 3.29 m/s. After volume expansion propagation velocities rose significantly and varied from 1.09 m/s to 6.48 m/s. During expiratory apnea and at peak negative expiratory pressure, the propagation speed of distinct pressure points was higher than during inspiratory apnea and at peak positive inspiratory pressure. Significant linear correlation coefficients were found between the transmission velocities of different distinct pressure points and the transmural pressure, but not between the propagation speed and the intraluminal pressure.