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Biomedical subjects

C Z Zhu

Publications and source records attributed to C Z Zhu.

8 recordsLinked to original sources
PubMed1992

Silent stroke and carotid stenosis.

BACKGROUND AND PURPOSE: Silent cerebral infarction is often found on computed tomographic scan in patients with asymptomatic carotid stenosis, but its relation to the arterial stenosis is uncertain. METHODS: We compared computed tomographic scans and carotid Doppler in 115 patients with asymptomatic carotid stenosis, 203 with carotid transient ischemic attacks and carotid stenosis, and 63 with transient ischemic attacks but without carotid stenosis. There was no group with normal carotid arteries for comparison. RESULTS: Lesions seen on CT scan were most common in the transient ischemic attack with carotid stenosis group (47%) compared with the other groups (30%, 19%) (p less than 0.001). Cerebral infarcts ipsilateral to the carotid stenosis were found in 10% of patients with mild (35-50%) stenosis, 17% in moderate (50-75%) stenosis, and 30% with severe (greater than 75%) carotid stenosis (p less than 0.001). In patients with asymptomatic carotid stenosis, 68% of infarcts were ipsilateral to the stenosis; in those with transient ischemic attacks and carotid stenosis, 86% of infarcts were ipsilateral to the stenosis. CONCLUSIONS: The more severe the carotid stenosis, the higher the incidence of cerebral infarction ipsilateral to the stenosis. This finding applied to central infarcts as well as to peripheral infarcts in both symptomatic and asymptomatic patients. Silent cerebral infarction may be an indication for carotid endarterectomy in asymptomatic patients.

Aged↗
PubMed1991

Vascular risks of asymptomatic carotid stenosis.

BACKGROUND AND PURPOSE: We sought to determine the risks of stroke, myocardial ischemia, and vascular death in patients with asymptomatic carotid stenosis. METHODS: Six hundred ninety-six patients with asymptomatic carotid stenosis referred to the Doppler laboratory were followed prospectively for a mean time of 41 months. These patients were studied both clinically and by carotid Doppler ultrasound, including evaluation of the effect of stroke risk factors. RESULTS: Transient ischemic attacks occurred in 75 patients and stroke in 29, while 132 had ischemic cardiac events. Five patients died from stroke and 59 from cardiac causes. Annual stroke rate was 1.3% in patients with carotid stenosis less than or equal to 75% and 3.3% in those with stenosis greater than 75%. Ipsilateral stroke rate was 2.5% in patients with greater than 75% carotid stenosis. Annual cardiac event rate was 8.3% and death rate 6.5% in patients with severe carotid stenosis. CONCLUSIONS: With carotid stenosis less than or equal to 75%, the stroke rate is negligible (1.3% annually) whereas the combined risk of cardiac ischemia and vascular death is as high as 9.9%. With stenosis greater than 75%, combined transient ischemic attack and stroke rate is 10.5% per year, with 75% of events ipsilateral to the stenosed artery.

Aged↗
PubMed1991

A therapeutic window for carotid endarterectomy in patients with asymptomatic carotid stenosis.

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.

Auscultation↗
PubMed1990

Stroke risk and critical carotid stenosis.

The risk of stroke from carotid stenosis is proportionate to the degree of stenosis, but whether this is a direct and linear relationship is unknown. Using the degree of carotid stenosis in 500 patients with asymptomatic carotid bruits as a continuous variable, we plotted the frequency distribution and related this to the risk of ischaemic cerebral events and the progression of the arterial lesion. There was a bi-modal distribution, with the junction of the two populations at 85% stenosis. The frequency of ischaemic cerebral events was maximal at 75-90% stenosis. Our data suggest that there is a critical degree of carotid stenosis at which stroke risk becomes maximal. This may represent a window of therapeutic opportunity.

Carotid Artery Diseases↗
PubMed1990

Role of carotid stenosis in ischemic stroke.

Using Doppler ultrasonography, we evaluated the frequency and severity of carotid artery stenosis in 261 patients with carotid ischemic strokes, 813 patients with carotid transient ischemic attacks, 500 patients with asymptomatic neck bruits, and 500 controls. Most patients with strokes and transient ischemic attacks had no associated carotid artery disease (55% and 64%, respectively), and such patients without neck bruits were even more likely to be without carotid artery disease (69% and 77%, respectively). Carotid stenosis was more frequent and more likely to be severe in symptomatic than in asymptomatic patients (p less than 0.0002), even after adjusting for age and sex. Carotid stenosis is present in only a minority of patients with strokes and transient ischemic attacks, especially if neck bruits are absent, and the cause of the ischemic cerebral events in most of these patients remains unexplained.

Age Factors↗