Key result
Diet-induced atherosclerosis increases arterial wave reflections without altering compliance or blood pressure in rabbits.
Why the study?
The effect of atherosclerosis on arterial impedance, a measure of arterial system function, had not been characterized.
In a rabbit model, early atherosclerosis increases arterial wave reflection due to local impedance mismatching before changes in global compliance or blood pressure occur.
May alter arterial impedance in atherosclerotic models; leaves open translation to human hemodynamics or risk.
Although atherosclerosis significantly alters the structural characteristics of the arterial tree, its effect on arterial impedance, which is a means of quantifying the functional characteristics of the arterial system, has not been characterized. To assess how one type of atherosclerosis affects impedance, we studied arterial impedance in New Zealand White rabbits after 11 wk on a 2% cholesterol diet. From open-chest aortic pressures and flows, impedance data were obtained from spectral analysis of randomly paced and Fourier analysis of nonpaced beats. Compliance was calculated from the low-frequency impedance moduli by assuming a windkessel model for the arterial system. Under base-line conditions, the atherosclerotic impedance phase spectrum in the low-frequency range remained negative for higher values of frequency than in controls. There was no difference between the groups in mean arterial blood pressure, impedance modulus spectrum, characteristic impedance, compliance, or total peripheral resistance. Wave reflections were, however, increased in the atherosclerotic animals. The differences between the two groups in phase and wave reflection were completely abolished after phenylephrine (3 micrograms.kg-1.min-1). Thus this study demonstrates that under base-line conditions atherosclerosis increases wave reflection at the input to the arterial system in the absence of an alteration in global arterial compliance, total peripheral resistance, or mean blood pressure. This increase is presumably secondary to atherosclerotic changes at arterial sites, which produce local impedance mismatching.
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Zuckerman et al. (1989) studied Atherosclerosis. 2% cholesterol diet vs. Controls was evaluated on Arterial impedance and wave reflections. Atherosclerosis induced by an 11-week 2% cholesterol diet in rabbits increased wave reflection at the input to the arterial system without altering global arterial compliance or mean blood pressure.
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