Adjustment of Pulse Wave Transit Time for Heart Rate

As recommended by international guidelines, the time delay between femoral and carotid pulse waves is determined using a foot-to-foot method.

Pulse wave recording sites

Fig. 8.6 Pulse wave recording sites (left panel) (C carotid, F femoral, T tail); measurement of the distance between carotid and tail arteries, with precision electronic sliding calipers, to determine pulse wave velocity (right panel)

Heart rate may be an important confounding factor that should be taken into account when performing analysis based on PWV measurements in rats. A direct, close relationship between pulse wave transit time delay from carotid to peripheral artery and heart period (R-R interval) was shown in several studies. Thus, pulse wave transit time delay (PWTT) should be normalized for a theoretical heart rate of 375 beats/min, corresponding to a heart period (HP), i.e., R-R interval of 160 ms.

Thus, pulse wave transit time (PWTT), resulting from this normalization, can be shown as PWTT@375 and PWV values as PWV@375. It is advised that the following formula is used to calculate PWTT@375:

where HP is the heart period (=60,000/HR). Thus, the formula used to calculate

PWV@375 is:

i.e.,:

and

 
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