Determining arterial wave transit time from a single aortic pressure pulse in rats: vascular impulse response analysis

Arterial wave transit time (τ(w)) in the lower body circulation is an effective biomarker of cardiovascular risk that substantially affects systolic workload imposed on the heart. This study evaluated a method for determining τ(w) from the vascular impulse response on the basis of the measured aortic pressure and an assumed triangular flow (Q(tri)). The base of the unknown Q(tri) was constructed with a duration set equal to ejection time. The timing of the peak triangle was derived using a fourth-order derivative of the pressure waveform. Values of τ(w)s obtained using Q(tri) were compared with those obtained from the measure aortic flow wave (Q(m)). Healthy rats (n = 27), rats with chronic kidney disease (CKD; n = 22), and rats with type 1 (n = 22) or type 2 (n = 11) diabetes were analyzed. The cardiovascular conditions in the CKD rats and both diabetic groups were characterized by a decrease in τ(w)s. The following significant relation was observed (P < 0.0001): τ(w)(triQ) = −1.5709 + 1.0604 × τ(w)(mQ) (r(2) = 0.9641). Our finding indicates that aortic impulse response can be an effective method for the estimation of arterial τ(w) by using a single pressure recording together with the assumed Q(tri).