Forward and backward waves in the arterial system, their relationship to pressure waves form

Abstract

The purpose of this work was to analyze, in human subjects, the shape of the aortic pressure wave from its forward and backward components calculated by use of Westerhof's model. Twenty-nine patients were studied: 11 normal subjects, 11 hypertensive patients and 7 patients with congestive heart failure. The following measurements and calculations were performed both under control conditions and during either angiotensin infusion in 5 normal subjects or nitroprusside infusion in 6 hypertensive patients: cardiac output, aortic blood pressure (catheter tip micromanometer), blood flow velocity (electromagnetic catheter-tip velocity transducer) in the ascending aorta, aortic impedance and reflection coefficients allowing the calculation of the aortic forward and backward pressure waves. The results show that the shape of aortic pressure wave in hypertensive patients is related to increased arterial wall stiffness which determines greater values and overlap of the forward and backward waves. This result is corroborated by the changes observed during angiotensin infusion in normal subjects. The shape of pressure wave in heart failure patients is dicrotic. This shape is related to smaller values and overlap of forward and backward waves. This appears related to a reduced stroke volume. During peripheral vasodilation the shape of pressure wave in hypertensive patients becomes dicrotic. However, this was mainly related to later backward waves. These results confirm that the shape of pressure waves depends both on the arterial wall stiffness and on the left ventricular performance: mainly on the stroke volume. The calculation of forward and backward waves allows a quantitative analysis of pressure waves.

The combined effect of augmentation index and carotid intima-media thickness on cardiovascular risk in young and middle-aged men without cardiovascular disease

“…Its values reflect the timing of reflected pressure waves returning to the aorta and therefore aortic pulse wave velocity and arterial stiffness 23,24 as well as changes associated with the intensity of the reflected waves which depends on the vascular tone and properties of the small muscular arteries/ arterioles. 11,12,15 It is not possible to determine which of these components was more strongly affected in the subjects with high AI in our study.…”

Large Artery Stiffness Assessment Using SphygmoCor Technology

“…The advantage of calculating the reflection magnitude in place of the AIx is that the reflection magnitude is not heart rate dependent - as, unlike the AIx, it is independent of the timing of the inflection point. However, resolving the incident and reflected pressure waves for calculation of the reflection magnitude requires both a measured pressure and a flow waveform at the same site, which are then decomposed into their frequency components [26]. …”

The Ankle-Brachial Index Is Related to Left Ventricular Ejection Fraction in Bonnet Macaques

“…A low ABI (<0.9) in either lower extremity is considered evidence of PAD and is an independent predictor of cardiovascular events including myocardial infarction, stroke and mortality [3,4]. The ratio is greater than 1.0 because the shape of the arterial waveform changes from the central aorta to the periphery with systolic BP rising at peripheral sites due to arterial waveform reflection and summation [5]. …”