Characterization of di‐gital, tri‐gital, and tetra‐gital temporal movement of systolic blood pressure on the arterial pulse waveform of rats at different vascular stiffness

Background An arterial stiffness is an indicator of many cardiovascular diseases. The temporal position of systolic blood pressure (BP) on aorta pulse waveform is assumed to gradually shift on the waveform in response to increasing/decreasing vascular stiffness. The animal model of rats and invasive methods that cannot be used in humans was applied to test the assumption on arterial pulse waveform (APW) of anesthetized rat. The aim of this study was to characterize the temporal movement of diastolic and systolic pressures on the APW of anesthetized rats during increasing/decreasing vascular stiffness. Methods The right jugular vein of anesthetized normotensive and spontaneously hypertensive rats was cannulated for intravascular administration of vascularly active compounds to alter systolic pressure and vascular stiffness. The left carotid artery was cannulated to detect APW, from which numerous APW parameters were evaluated. Results During increases/decreases in systolic BP or stiffness, the temporal position of diastolic BP of individual heartbeats di‐gitally shifted on the APW between two temporal positions ~8–12 ms apart, and the temporal position of systolic BP on the APW did not gradually shift during increases/decreases in vascular stiffness, as expected, but oscillated between constant di‐gital, tri‐gital, or tetra‐gital temporal positions. Conclusions Introducing new APW parameters, n ‐gital systolic BP fluctuations on rat APW were found. Fluctuations in n ‐gital were approximately constant during large changes in systolic pressure despite significant changes in augmentation index and cardiovascular stiffness, which may challenge the assumption of a gradual temporal location of systolic pressure on rat APW under these conditions.