Non-Invasive Assessment of Arterial Stiffness: Pulse Wave Velocity, Pulse Wave Analysis and Carotid Cross-Sectional Distensibility: Comparison between Methods

Abstract

Background: The stiffening of large elastic arteries is currently estimated in research and clinical practice by propagative and non-propagative models, as well as parameters derived from aortic pulse waveform analysis. Methods: Common carotid compliance and distensibility were measured by simultaneously recording the diameter and pressure changes during the cardiac cycle. The aortic and upper arm arterial distensibility was estimated by measuring carotid−femoral and carotid−radial pulse wave velocity (PWV), respectively. The augmentation index and blood pressure amplification were derived from the analysis of central pulse waveforms, recorded by applanation tonometry directly from the common carotid artery. Results: 75 volunteers were enrolled in this study (50 females, average age 53.5 years). A significant inverse correlation was found between carotid distensibility and carotid−femoral PWV (r = −0.75; p < 0.001), augmentation index (r = −0.63; p < 0.001) and central pulse pressure (r = −0.59; p < 0.001). A strong correlation was found also between the total slope of the diameter/pressure rate carotid curves and aortic distensibility, quantified from the inverse of the square of carotid−femoral PWV (r = 0.67). No correlation was found between carotid distensibility and carotid−radial PWV. Conclusions: This study showed a close correlation between carotid−femoral PWV, evaluating aortic stiffness by using the propagative method, and local carotid cross-sectional distensibility.

Keywords: aorta; arterial distensibility; arterial stiffness; augmentation index; blood pressure amplification; cardiovascular prevention; elastic modulus; pulse wave analysis; pulse wave velocity.

Figure 1

Upper panel: original tracings of carotid diameter (red line) and simultaneously acquired blood pressure (white line) wave. Lower panel: on the left arterial pressure wave (black line) and curves of cross-sectional diameter changes (red line); a–b interval indicates the proto-mesosystolic phase, and c–a’ is the late diastole phase (lower panel). Cross-sectional diameter/pressure curves are shown in the right lower panel.

Figure 2

Relationship between age and carotid–femoral pulse wave velocity PWV_CF (continuous line, open squares) and carotid–radial pulse wave velocity PWV_CR (dotted line, closed triangles).

Figure 3

Carotid cross-section pressure curves in individuals aged 20–45 years (red lines, females; yellow lines, males) and over 70 years old (green lines, females; blue lines, males).

Figure 4

Slope of the cross-section diameter–pressure curves are separately shown for the different age tertiles. Mean values and standard deviation (open rectangles) are shown.

Figure 5

Univariate linear relationship between the slope of the cross-section carotid diameter-pressure curves and aorta distensibility [1/(carotid–femoral PWV)²].