Artery Research (Dec 2020)
P.23 Relationship Between Aortic Stiffness, Aortic, and Carotid Impedance with Vascular Aging in Community-Based Healthy People
Abstract
Background: Stiffening of the aorta has been associated with microvascular structural brain damage and cognitive dysfunction in cross-sectional and longitudinal studies, probably due to the reduced wave reflection at the interface between carotid and aorta and transmission of excessive flow pulsatility into the brain. The present study investigated whether age-related stiffening of the proximal aorta is disproportionately greater than the carotid arteries and whether the coupling of stiffness between proximal aorta and carotid arteries affects wave reflection at the interface. Methods: Comprehensive pulsatile hemodynamics evaluation using applanation tonometry, carotid ultrasonography and echocardiography was performed in 1236 apparently healthy community residents (age range 40 to 96 years, average 62.4 ± 10.5 years) who had no history of cardiovascular events and stroke. Aortic (Zc) and carotid (CCI) characteristic impedance were estimated in the time domain. Carotid pulsatility index (PI) was computed from the carotid flow and a carotid reflection coefficient was computed from bilateral carotid impedance and distal aortic impedance. Results: CFPWV (Standardized Beta = 0.56, p < 0.001), CCI (Beta = 0.46, p < 0.001) and carotid reflection coefficient (Beta = 0.26, p < 0.001) significantly increased with age. In contrast, PI (Beta = −0.06, p = 0.026) significantly decreased with age, and a U-shape association between Zc (Beta = 0.09, p = 0.002) and age was found. Carotid flow PI was significantly related to the aorta-carotid reflection coefficient negatively (r = −0.28, p < 0.001). Conclusions: In this healthy population, stiffening of the proximal aorta was not disproportionately greater than that of the carotid arteries. This might favorably maintain the wave reflection at the carotid-aorta interface so that carotid flow PI did not increase with age. Age group 40∼49 50∼59 60∼69 ≧70 p value for trend n = 1236 n = 137 n = 356 n = 445 n = 298 Age (years) 45 (3) 55 (3) 64 (3) 76 (5) <0.001 Male (male, %) 53 (41.7) 153 (43.7) 207 (47.2) 159 (55.0) 0.002 Height (cm) 162.5 (8.1) 161.5 (8.1) 159.5 (7.5) 158.3 (8.2) <0.001 Weight (kgw) 64.0 (12.7) 64.7 (10.6) 63.0 (10.4) 62.0 (10.9) 0.004 BMI (kgw/m2) 24.1 (3.6) 24.7 (3.3) 24.7 (3.3) 24.7 (3.4) 0.31 HTN (n, %) 9 (7.1) 76 (21.7) 172 (39.2) 158 (54.7) <0.001 DM (n, %) 5 (3.9) 32 (9.1) 78 (17.8) 71 (24.6) <0.001 Hyperlipidiemia (n, %) 6 (4.7) 50 (14.3) 229 (52.2) 144 (49.8) <0.001 Creatinine (mg/dL) 0.77 (0.45) 0.73 (0.21) 0.79 (0.27) 0.93 (0.57) <0.001 LDL (mg/dL) 116.5 (34.8) 120.0 (35.9) 117.7 (34.1) 113.3 (35.1) 0.083 Glucose (mg/dL) 94.5 (18.1) 100.4 (21.2) 104.3 (28.2) 105.3 (26.3) <0.001 Smoking (n, %) 0.08 Non-smoker 95 (74.8) 255 (72.9) 341 (77.7) 204 (70.6) Current-smoker 14 (11.0) 44 (12.6) 38 (8.7) 14 (4.8) former-smoker 18 (14.2) 51 (14.6) 60 (13.7) 71 (24.6) MMSE score < 24 0 3 (0.9) 13 (3.0) 31 (10.8) <0.001 Echocardiography variables Ea (mmHg/ml) 1.86 (0.44) 1.78 (0.43) 1.70(0.43) 1.70 (0.53) <0.001 Ees (mmHg/ml) 4.00 (1.06) 4.09 (1.06) 3.67 (1.12) 3.99 (1.73) 0.12 Ea/Ees 0.48 (0.09) 0.45 (0.09) 0.48 (0.12) 0.45 (0.13) 0.87 Stroke volume (ml) 58.5 (12.3) 64.0 (14.2) 69.5 (14.9) 72.5 (17.6) <0.001 Cardiac index (L/min/m2) 2.4 (0.6) 2.6 (0.6) 2.7 (0.6) 2.9 (0.8) <0.001 Ef (%) 69.5 (6.2) 70.7 (6.4) 68.8 (7.1) 68.5 (7.9) 0.001 Data were presented as mean(SD). BMI, body mass index; HTN, hypertension; DM, diabetes mellitus; LDL, low density lipoprotein; MMSE, mini-mental state examination; Ea, arterial elastance; Ees, left ventricular end-systolic elastance; LVEDV, left ventricular end-diastolic volume; LVESV: left ventricular end-systolic volume. Table 1Subjects characteristics (subdivided into groups according to the age) Age group 40∼49 50∼59 60∼69 ≧70 p value for trend n n = 137 n = 356 n = 445 n = 298 Central SBP (mmHg) 107.0 (16.2) 112.5 (13.9) 118.0 (15.5) 121.6 (14.9) <0.001 DBP (mmHg) 74.3 (12.5) 77.8 (10.2) 78.8 (10.6) 77.5 (9.7) <0.024 PP (mmHg) 33.6 (7.1) 35.5 (7.4) 40.1 (8.7) 45.3 (9.9) <0.001 Brachial SBP (mmHg) 120.2 (17.3) 125.3 (15.1) 131.2 (16.8) 134.6 (16.5) <0.001 DBP (mmHg) 73.3 (12.5) 76.8 (10.2) 77.5 (10.5) 76.1 (9.7) 0.70 PP (mmHg) 41.2 (9.1) 43.7 (11.7) 48.9 (11.7) 53.4 (12.6) <0.001 MAP (mmHg) 90.9 (14.3) 95.0 (12.4) 98.4 (13.6) 99.9 (12.5) <0.001 Heart rate (bpm) 69 (9.7) 69 (10.3) 66 (10.2) 66 (10.3) <0.001 pf (mmHg) 28.8 (7.1) 28.1 (6.6) 30.2 (6.9) 34.5 (8.7) <0.001 pb (mmHg) 14.5 (3.1) 15.4 (3.3) 17.7 (3.8) 19.5 (4.4) <0.001 CFPWV (m/s) 9.4 (1.9) 10.8 (2.4) 12.4 (3.1) 15.2 (4.4) <0.001 Aortic flow-pressure Zc (dyne⋅s/cm5) 102.3 (32.2) 89.6 (31.6) 90.8 (38.4) 104.7 (50.7) 0.027 SVR (dyne⋅s/cm5) 1782.0 (551.4) 1685.2 (435.7) 1683.7 (441.9) 1664.0 (543.7) 0.06 Mean flow (ml/s) 63.4 (16.6) 69.6 (19.7) 70.7 (17.4) 73.7 (20.6) <0.001 normalized Zc 0.06 (0.02) 0.05 (0.02) 0.05 (0.02) 0.06 (0.02) <0.001 Carotid flow-pressure CCI (dyne⋅s/cm5) 2060.2 (520.5) 2198.2 (708.0) 3183.0 (1030.9) 3328.3 (1154.5) <0.001 CVR (dyne⋅s/cm5) 9421.3 (2472.4) 9860.9 (2049.4) 11879.2 (2612.3) 12347.4 (3022.2) <0.001 Mean flow (ml/s) 13.2 (2.5) 13.1 (2.3) 11.2 (2.2) 10.9 (2.2) <0.001 normalized CCI 0.22 (0.05) 0.23 (0.06) 0.27 (0.08) 0.27 (0.08) <0.001 Data were presented as mean(SD). SBP, systolic blood pressure; DBP, diastolic blood pressure; PP, pulse pressure; MAP, mean arterial pressure; pf, forward pressure; pb, backward pressure; CFPWV, carotid-femoral pulse velocity; Zc, aortic characteristics impedance; SVR, systemic vascular resistance; CCI, carotid characteristics impedance; CVR, carotid vascular resistance. Table 2Hemodynamics parameters (subdivided into groups according to the age)
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