Measurement of Circumferential Strain Distribution in Human Coronary Arteries with Atherosclerotic Plaque

Abstract

Rupture of atherosclerotic plaque in coronary artery causes serious results. Since heterogeneously distributed plaque may cause local stress concentration, the local strain in circumferential direction of the coronary artery with atherosclerosis was investigated. For eight specimens from four human atherosclerotic coronary arteries, four needles were stuck into each the specimen at equal intervals on their circumference. Specimens were pressurized and local circumferential length was calculated from movement of the needles observed from longitudinal direction. For each specimen, pressure strain elastic modulus E_p, stiffness parameter β, and incremental elastic modulus E_inc were calculated. Local circumferential strain was calculated by referring to circumferential length at no-stress state. Total thickness T_total, plaque thickness T_plaque, medial and adventitial wall thickness T_wall, and area fraction of plaque A_plaque were also measured in histological sections. E_p and β obtained in the present study were almost comparable to those of nonatherosclerotic human coronary arteries in previous studies. Local strains were different even in a circumference. The local strain at 80 mmHg ε₈₀ correlated significantly with T_wall (r = 0.48, p < 0.05), while ε₈₀ had insignificant correlation with T_plaque, T_total, and A_plaque. Coefficient of variance of local T_wall decreased with the increase in the pressure. These results indicate that mechanical properties of human atherosclerotic coronary arteries are heterogeneously distributed in circumferential direction, plaque has insignificant effect to their mechanical properties, and T_wall becomes more uniform at physiological state than at no-stress state. These dada may be useful to simulate stress distribution in atherosclerotic coronary artery.