Non-invasive one-point carotid wave intensity in a large group of healthy subjects

The analysis of wave intensity (WI) evaluates the working condition of the heart interacting with the arterial system. WI in normal subjects has two peaks, the first (W ₁) reflects left ventricle (LV) contractile performance, the second (W ₂) is related to the ability of the LV to actively stop aortic blood flow. The aim of the study was to investigate the reference values of W ₁ and W ₂ in a group of apparently healthy subjects through a radiofrequency-based system. 680 subjects (388 men mean age 43.0 ± 17.4 years, range 16–92; 292 women mean age 44.8 ± 17.7 years, range 16–86) were enrolled and underwent physical examination, blood pressure (BP) and heart rate (HR) measurements and comprehensive transthoracic echocardiogram was performed. Measurement of local WI was obtained at the level of the left common carotid artery before the bifurcation, using a high definition echo-tracking system. W ₁ was (12.37 ± 6.89) × 10³ and (9.76 ± 4.8) × 10³ mmHg m/s³, p < 0.0001; W ₂ was (3.21 ± 1.81) × 10³ and (2.98 ± 1.69) × 10³ mmHg m/s³, p = ns in men and women, respectively. The cohort was divided into 5 age groups (ages 16–29; 30–39; 40–49; 50–59; >60) and stratified by gender. After adjustment for height, systolic BP and HR, W ₁ decreased with age (p < 0.0001 in men and p = 0.026 in women for trend) while no relation was found for W ₂. Multivariable regression analysis using age, gender, height, systolic BP, HR, ejection fraction and stroke volume indexed by body surface are predicted W ₁ and age, systolic BP, HR and E/A as a measure of diastolic function, predicted W ₂. Inter and intra-observer variability and feasibility of WI analysis were satisfactory. We reported the values and their clinical correlations of the two peaks (W ₁ and W ₂) of WI, a non-invasive hemodynamic index for assessing ventricular–arterial coupling in a large group of apparently healthy subjects.