Systolic aortic pressure-time area is a useful index describing arterial wave properties in rats with diabetes

Abstract

The accurate measurement of arterial wave properties in terms of arterial wave transit time (τw) and wave reflection factor (Rf) requires simultaneous records of aortic pressure and flow signals. However, in clinical practice, it will be helpful to describe the pulsatile ventricular afterload using less-invasive parameters if possible. We investigated the possibility of systolic aortic pressure-time area (PTAs), calculated from the measured aortic pressure alone, acting as systolic workload imposed on the rat diabetic heart. Arterial wave reflections were derived using the impulse response function of the filtered aortic input impedance spectra. The cardiovascular condition in the rats with either type 1 or type 2 diabetes was characterized by (1) an elevation in PTAs; and (2) an increase in Rf and decrease in τw. We found that an inverse linear correlation between PTAs and arterial τw reached significance (τw = 38.5462 − 0.0022 × PTAs; r = 0.7708, P < 0.0001). By contrast, as the PTAs increased, the reflection intensity increased: Rf = –0.5439 + 0.0002 × PTAs; r = 0.8701; P <0 .0001. All these findings suggested that as diabetes stiffened aortas, the augmented aortic PTAs might act as a useful index describing the diabetes-related deterioration in systolic ventricular workload.

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

“…This study has several limitations17. Because Z i cannot be measured in conscious animals, evaluating the effects of pentobarbital anesthesia on rats is impossible.…”

“…The levels of SCr and BUN were measured with an autoanalyzer (Model 7070, Hitachi Electronics Co., Ltd., Tokyo, Japan). Type 1 DM was induced using a single tail vein injection with 55 mg kg −1 of STZ (Sigma, St. Louis, MO, USA) in 0.1 M citrate buffer (pH 4.5) (Sigma, St. Louis, MO, USA)17. Type 2 DM was induced by administering intraperitoneally 180 mg kg −1 of NA (Sigma, St. Louis, MO, USA) 30 min before an intravenous injection of 50 mg kg −1 of STZ dissolved in 0.1 M citrate buffer (pH 4.5)2021.…”

“…The general surgical procedures and method used to measure the cardiovascular variables in the anesthetized rats were performed as described previously17. In brief, the rats were anesthetized using intraperitoneal sodium pentobarbital (50 mg kg −1 ), placed on a heating pad, intubated, and ventilated with a rodent respirator (Model 131, New England Medical Instruments, Medway, MA, USA).…”

“…The timing asynchronicity between the pressure and flow signals caused by the spatial distance between the flow probe and the proximal aortic pressure transducer was corrected using a time-domain approach, wherein the foot of the pressure waveform was realigned with that of the flow22. The resulting aortic pressure and flow signals were subjected to further vascular impedance analysis41117.…”

“…1) and around the incisura (third vertical blue line in Fig. 1), respectively17. The timing of the peak triangle was derived from the fourth-order derivative of pressure waveform (pink curve in Fig.…”