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

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_ws 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_ws. The following significant relation was observed (P < 0.0001): τ_w^triQ = -1.5709 + 1.0604 × τ_w^mQ (r² = 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.