Zhu C Z, Norris J W
Stroke Research Unit, Sunnybrook Health Science Centre, University of Toronto, Ont.
Can J Surg. 1991 Oct;34(5):437-40.
The natural history of asymptomatic carotid stenosis was prospectively and systematically studied in 500 patients by clinical observation and carotid Doppler ultrasonography. In the 40% of carotid arteries (398) with an initial stenosis of over 35%, there were apparently two separate populations, with a cutoff point of 85% stenosis. There were 79 ischemic cerebral events (54 transient ischemic attacks and 25 strokes) among the 500 patients during 60 months of follow-up, predominantly in the severe-stenosis (more than 75%) group, with few events occurring in the near-or total-occlusion (95% to 100% stenosis) group; the highest incidence was in patients whose arteries had 75% to 90% stenosis. These observations indicate a critical degree of carotid stenosis at which stroke risk becomes maximal, declining as the artery becomes occluded. These findings suggest that there may be a "window" for carotid endarterectomy in patients with asymptomatic carotid stenosis, when the stroke risk may be high enough (5.5%/year) to warrant surgery.
通过临床观察和颈动脉多普勒超声检查，对500例患者无症状性颈动脉狭窄的自然病史进行了前瞻性和系统性研究。在最初狭窄超过35%的40%的颈动脉（398条）中，明显存在两个不同的群体，狭窄程度的分界点为85%。在500例患者60个月的随访期间，共发生79次缺血性脑事件（54次短暂性脑缺血发作和25次中风），主要发生在重度狭窄（超过75%）组，近闭塞或完全闭塞（95%至100%狭窄）组发生的事件很少；发病率最高的是动脉狭窄75%至90%的患者。这些观察结果表明，存在一个关键的颈动脉狭窄程度，在此程度时中风风险达到最大，随着动脉闭塞风险下降。这些发现表明，对于无症状性颈动脉狭窄患者，当中风风险可能高到足以（每年5.5%）值得进行手术时，可能存在颈动脉内膜切除术的“窗口期”。
