The Influence of Slow Blood Volume Waves on the Shape of the Dicrotic Complex

Recorded arterial blood volume pulses are often superimposed on slow rhythmic volume waves. It was noticed that in such recordings the dicrotic complex changes its shape as a function of the volume wave; on the ascending limb of the volume wave the dicrotic complex becomes more pronounced, whereas on the descending limb it becomes attenuated. In order to explain this observation a mathematical analysis of the recording was performed. The analysis suggests that the changes in the shape of the dicrotic complex can be explained by assuming a superposition of arterial wall extensions caused by volume changes due to 1) the downstroke of the volume pulse, 2) the dicrotic complex, and 3) the ascending (or descending) limb of the volume wave. Three functions simulating these three vascular events were electronically generated and superimposed. The result shows that the simulated dicrotic complex changes its shape in a similar manner as in the physiological recording, strengthening the proposed explanation. The origin of the dicrotic complex and of rhythmic waves in blood volume and blood pressure is still unclear and their interaction, therefore, is difficult to understand. The present paper offers a possible explanation for a case in which the shape of the dicrotic complex, appearing on a blood volume pulse, changes as a function of a rhythmic volume wave.