Severe Asymptomatic Carotid Artery Stenosis Research Articles

Transcranial Doppler Waveform Blunting in Severe Extracranial Carotid Artery Stenosis

Objective: To investigate the frequency of transcranial Doppler (TCD) waveform blunting in patients with severe (80–99%) symptomatic or asymptomatic extracranial carotid artery stenosis. Background: Severe carotid artery stenosis has been identified as a risk factor for ischemic stroke. Blunted Doppler flow waveforms (reduced systolic flow velocity and pulsatility) of the middle cerebral artery (MCA) are inferred to reflect hemodynamic impairment, possibly indicating an increased risk of stroke. Methods: The 114 consecutive patients (mean age 72.4 years, SD 9.0 years; 37% women; 46 clinically symptomatic, 68 asymptomatic) with 80–99% stenosis of the extracranial internal carotid artery (ICA), as determined by duplex sonography, were examined with TCD. Flow velocities, pulsatility index, and spectral waveforms of the MCA distal to the ICA stenosis were assessed blinded to the clinical status of the ICA: Doppler waveform blunting was defined as loss of the characteristic systolic peak. Odds ratios with 95% confidence intervals and χ² statistics were used to describe the association between waveform blunting and the symptomatic status of the ICA stenosis. Results: Among symptomatic patients, 23 (50%) had completed strokes, and a further 23 (50%) had transient neurologic deficits in the territory of the stenotic ICA. Blunted spectral waveform was found in 37 (80%, 95% CI 68–92%) of the symptomatic and 25 (37%; 95% CI 25–49%) of the asymptomatic patients. Symptomatic patients had significantly increased odds of having blunted TCD waveforms (OR 7.5, 95% CI 3.1–18.1, p < 0.001). Conclusions: Our findings suggest that TCD waveform blunting in the MCA as here described may be an additional risk factor in the setting of severe extracranial carotid artery stenosis. A prospectively designed study to confirm our results seems warranted.

無症候性頸動脈狭窄症に対する血行再建術-Stentingの現状をCEAと対比して-

Several large randomized multicenter trials have demonstrated the beneficial effects of carotid endarterectomy (CEA) for prevention of strokes in patients with severe symptomatic or asymptomatic carotid artery stenosis. On the other hand, endovascular treatments are rapidly evolving as alternatives to CEA, but indication for endovascular treatment remain uncertain and long-term results have not yet been established. We experienced 59 consecutive patients with asymptomatic carotid artery stenosis treated with CEA in 5 recent years, and 14 patients with asymptomatic carotid artery stenosis treated with stenting since 1997. One minor stroke (1.7%, hemiparesis and aphasia) and 1 transient neurological event occurred after CEA, and one major stroke (7.1%, hemiplegia) occurred during stenting by distal embolic occlusion of MCA and ACA. There were no neurological events after either CEA or stenting, but distal embolic signals were detected in all patients with TCD during stenting, and embolic lesions were detected in more than half the patients with MRI/DWI after stenting.We consider that cerebral protection by means of balloon is mandatory to eliminate embolic complication in the endovascular treatment of carotid artery stenosis. Stenting for asymptomatic carotid artery stenosis can now be indicated only for surgically high-risk patients who are very old, have severe heart or pulmonary disease, contraindication to general anesthesia, high-positioned stenosis, restenosis after CEA or PTA, or radiation-induced stenosis.