中度狭窄病变中斑块分布对冠状动脉生物力学特性的影响

Effect of Plaque Distribution on Biomechanical Characteristics of Angiographic Intermediate Coronary Stenosis

目的探讨中度狭窄病变中斑块分布对冠状动脉生物力学特性的影响及其临床意义。方法对82例冠状动脉造影示中度狭窄(直径狭窄40%～60%)患者行血管内超声显像(IVUS)检查,根据斑块分布分为向心型斑块组(n=50)和偏心型斑块组(n=32)。测定病变血管的膨胀性指数、硬度及斑块面积的变化。结果偏心型斑块组与向心型斑块组狭窄程度相似[(53.9±89)%vs(584±98)%]。偏心型斑块组血管膨胀性指数显著大于向心型斑块组(21±03vs12±02,P<001),而硬度β显著低于向心型斑块组(81±13vs294±72,P<001)。心动周期中偏心型斑块组斑块面积的变化程度显著大于向心型斑块组[(052±022)mm2vs(024±019)mm2,P<001],偏心型斑块组正重构的比例显著多于向心型斑块组(64%vs9%,P<001)。结论偏心型斑块病变的血管膨胀性及斑块膨胀性增大,这可能导致偏心型斑块易于破裂。

Objective:The effect of plaque distribution on biomechanical characteristics of angiographic intermediate coronary stenosis was investigated using intravascular ultrasound (IVUS). Methods:In 82 patients of angiographic mild coronary stenosis (diameter stenosis by 40%—60%),IVUS imaging was performed and intracoronary pressure was recorded.The patients were classified into either eccentric plaque group ( n =50) or concentric plaque group ( n =32) according to IVUS images.The biomechanical properties (distensibility index and stiffness) of coronary artery were calculated and plaque behavior during cardiac cycle was determined. Results:There was no significant difference in stenosis between eccentric plaque group and concentric plaque group (53 9±8 9% vs 58 4±9 8%, p >0 05).The coronary distensibility index in the eccentric plaque group was significantly greater than that in the concentric plaque group (2 1±0 3 vs 1 2±0 2, p <0 01),but stiffness β of the eccentric plaques was significantly greater than that of the concentric plaques (8 1±1 3 vs 29 4±7 2, p <0 01).The change of plaque area during cardiac cycle (plaque distensibility) was more significant in the eccentric plaque group than that in the concentric plaque group (0 52±0 22 mm 2 vs 0 24±0 19mm 2, p <0 01).Positive remodeling occurred more frequently with eccentric plaques than with concentric plaques (64% vs 9%, p <0 01). Conclusions:High coronary artery distensibility and high plaque distensibility of eccentric lesions during cardiac cycles will result in increased plaque vulnerability.