Development of a method for determining arterial pulse propagation times and influence of arterial compliance

The characteristics of the arterial wall play an important role in cardiovascular physiology and pathophysiology. Arteries are normally elastic or compliant, allowing the artery diameter to expand under pressure. However, very little is known about this important property, as it is difficult to assess in vivo. This study examined this property indirectly from measurements of the time the pulse took to radiate from the heart to peripheral sites on the body. By examining beat-to-beat changes in pulse timing, the effects on arterial compliance were estimated. Subjects with frequent ectopic beats were studied. Electrocardiogram (ECG) and finger and ear photoplethysmograph (PPG) recordings were obtained from all subjects. ECG-pulse times for ear and finger pulses were determined by computer algorithms. The differences in pulse propagation time between sinus beats and ectopic beats with lower pulse pressure were quantified. The ECG-pulse time for ectopic beats was significantly greater than for the sinus beats. The finger ECG-pulse time for ectopic beats was 344+14 ms compared with 228+11 ms for sinus beats (P<0.001), and the ear ECG- pulse time was 288+20 ms compared with 180+13 ms (P<0.001). The differences between the finger and ear ECG-pulse times allowed the pulse propagation time along the arm to be estimated. It was significantly longer for the ectopic beats than for the sinus beats (55.7+8.0 ms compared to 47.7+4.0 ms). This 18% change resulted from the lower pulse pressure of ectopic beats and increased arterial compliance of 42%.