Pattern analysis of temporal changes in the carotid artery diameter under normal and pathological conditions

Abstract

Age-related and temporal cyclic changes in the left and right common carotid arteries (CCA) diameters were studied in two groups of subjects: (i) 11 healthy normotensive subjects (ages 19–72 years), and (ii) eight hypertensive subjects (ages 59–85 years), with various degrees of stenosis in their ICA. Cross-sectional images of the left and right CCA were acquired via an ultrasonic system. Images were digitized, and the contour of the arterial wall for each frame was manually traced. Assuming a circular geometry, the arterial diameter was calculated. Averaging four to six consecutive heart beats yielded the typical patterns of temporal diameter changes for both the left and right CCA. For the group of normal subjects, a typical pattern of the temporal diameter changes with a consistent left vs right peak diameter delay (LRPDD), with the right CCA preceding the left, was observed. Plotting the normalized left vs right CCA diameters yielded a typical loop (DDloop) which changed in the counter-clockwise direction from systole to diastole. For the group of hypertensive subjects, the LRPDD decreased or became negative with the left CCA preceding the right if the stenosis degree exceeded 50% ( p<0.01). The DDloop changed from a counterclockwise to a clockwise direction. For the group of normal subjects, end diastolic, end systolic diameters and the elastic index of the CCA increased with age while the relative systolic change in diameter decreased with age. For the group of hypertensive subjects, the relative systolic change in diameter was smaller, compared to normals (7.8±1.2% vs 10.7±3.1%, respectively; p<0.05). The elastic index for this group was significantly higher compared to the normal subjects (1.4±0.3 vs 0.6±0.2×10 6 dynes/cm 2, respectively; p<0.001). These findings imply that patterns of CCA temporal diameter changes can indicate the existence of a pathological state.