ABSTRACT
Aortic Windkessel function is thought to represent a potential cardiovascular risk factor. As an indicator for the function, we have recently introduced the decay index (DI). DI is the coefficient of an exponential function applied to the postpeak portion of internal carotid artery Doppler waveform, and is inversely associated with the function. This study compares DI with age, gender and traditional cardiovascular risk factors in 220 apparently healthy volunteers (59 +/- 16 years). DI increased linearly with age (r = 0.51, p < 0.001), and was higher in women than in men at all ages (p < 0.001). Also, DI was positively associated with systolic blood pressure (beta = 0.17, p < 0.01) and diabetic medication (beta = 0.14, p < 0.05), independent of age (beta = 0.49, p < 0.0001), gender (beta = 0.27, p < 0.0001) and other traditional cardiovascular risk factors (model r(2) = 0.36). Based on the present results, the Windkessel function as assessed by DI declines with age and is lower in women. However, the associations with cardiovascular risk factors need to be established on a larger sample at higher cardiovascular risk.
Subject(s)
Aging/physiology , Aorta/diagnostic imaging , Aorta/physiopathology , Cardiovascular Diseases/etiology , Cardiovascular Diseases/physiopathology , Coronary Circulation/physiology , Diastole/physiology , Systole/physiology , Adult , Age Factors , Aged , Blood Pressure/physiology , Cardiovascular Diseases/diagnostic imaging , Carotid Artery, Internal/diagnostic imaging , Carotid Artery, Internal/physiopathology , Female , Humans , Male , Middle Aged , Reference Values , Risk Factors , Severity of Illness Index , Sex Factors , Transducers , UltrasonographyABSTRACT
The Windkessel function of elastic arteries determines the postpeak contour of the internal carotid artery (ICA) Doppler waveform. To introduce an indicator for the function, the postpeak contour was reproduced by an exponential function, and the exponential coefficient was termed "Decay Index" (DI). DI obtained from 108 stenosis-free ICAs (55.2 +/- 15.8 y) was compared with surrogate measures for the Windkessel function (aortic pulse wave velocity, pulse pressure) and ICA peripheral resistance (resistive index, pulsatility index, systolic-to-diastolic ratio). DI was moderately correlated with the Windkessel and the resistance measures (r ranged 0.44-0.57). To clarify these intercorrelations, principal component analysis revealed two components. The first was loaded by the resistance measures (component load > or = 0.93) although the second was loaded by the Windkessel measures and DI (> or = 0.70), supporting an association between DI and the Windkessel function. Thus, DI is likely to represent an indicator for the Windkessel function.
