Effect of contralateral carotid ligation on experimental carotid artery aneurysm in the rat.

Haemodynamic factors in the formation and development of saccular aneurysms have been widely studied. Saccular aneurysms could appear and grow at the side of the increased blood flow. The effects of contralateral carotid ligation on the formation and growth of our experimental saccular aneurysms were studied. Measurement and pathological examination showed that the haemodynamic changes could facilitate the development of saccular aneurysms, but by itself could not bring about their formation.     

一侧颈动脉狭窄伴对侧颈动脉闭塞患者颈动脉支架置入术的脑保护措施

目的 探讨一侧颈动脉狭窄伴有对侧颈动脉闭塞的高危患者实施支架置入术前及术中的脑保护措施对降低围手术期缺血事件发生的有效性. 方法 12例患者术前均进行血流阻断耐受试验,对2例重度不能耐受缺血负荷的患者术前进行颅内外血管吻合术,对2例相对不耐受缺血负荷的患者选择在全身麻醉下进行支架置入术.术中采取减少脑血流阻断时间、降低血栓形成等各种有效脑保护措施,防止缺血事件的发生.术后通过弥散加权MRI(DWI)检查及缺血性神经症状的临床表现,评估脑保护措施的有效性. 结果 术后出现短暂性脑缺血发作3例,出现一过性失明1例,出现永久性缺血神经症状1例.术后24 h DWI阳性率为50.0%,多为小于1～2 mm小病灶散在分布.术后颈动脉血管扩张达90%以上8例,70%-90%4例. 结论 术前正确评估缺血耐受程度及血流特征,术中有效缩短血流阻断时间及防止血栓形成或栓子脱落等脑保护措施可有效降低一侧颈动脉狭窄伴有对侧颈动脉闭塞的高危患者在围手术期发生永久性缺血事件发生.     

颈动脉内膜切除术后对侧颈内动脉的变化情况

目的观察颈动脉内膜切除术(CEA)后对侧颈内动脉变化情况。方法回顾性分析127例因一侧颈内动脉高度狭窄而实施CEA病人的临床资料,每隔1年行1次双侧颈动脉超声检查,定期检查双侧颈动脉狭窄情况。结果随访1~110个月,平均32.8个月,从实施CEA到对侧颈内动脉出现显著狭窄时间为50.7个月;出现对侧颈内动脉进行性狭窄达70%以上12例。这12例虽合并高血压、高脂血症或冠脉疾病,但与非进行性狭窄病人经统计学分析无显著差异(P>0.05)。结论 CEA术后对侧颈内动脉出现进行性狭窄的显著危险因子尚未发现,定期检查及密切观察预后非常重要。     

Anomalous internal carotid anastomosis to contralateral anterior cerebral artery

BACKGROUND: Many anomalies and variants in vascular anatomy have been reported in relation to the anterior cerebral artery (ACA). PATIENTS AND METHODS: We encountered an apparently novel anomaly in a 30-year-old man admitted for disturbance of consciousness following a traffic accident. Computed tomography revealed an acute subdural hematoma and subarachnoid hemorrhage. RESULTS AND CONCLUSIONS: No vascular abnormalities related to the hemorrhage were detected by conventional angiography, so we concluded that the bleeding was of traumatic origin. Anomalous origin of the ACA was disclosed incidentally, with both A1 segments arising from the right internal carotid artery; no normal A1 segment of the left ACA was visualized. We discuss possible bases for this anomalous origin.     

Detection of intracranial emboli in patients with symptomatic extracranial carotid artery disease.

BACKGROUND AND PURPOSE: Cerebral embolism from extracranial sources is an important cause of ischemic stroke. The purpose of this limited study using long-term transcranial Doppler ultrasonographic monitoring was to estimate the frequency of clinically silent intracranial embolisms in patients with symptomatic extracranial carotid artery disease. SUMMARY OF REPORT: By means of a 2-MHz pulsed-wave transcranial Doppler instrumentation, three consecutive patients with extracranial internal carotid artery stenosis (n = 2) or occlusion (n = 1) and recurrent ipsilateral ischemic events were monitored (19 hours total recording time). In addition, 10 control subjects without cerebrovascular disease were studied (25 hours total recording time). Formed-element emboli were defined as distinct signals within the fast Fourier-transform Doppler spectrum that were < 70 msec in duration and > 9dB greater in intensity than the background signal. Clinically silent formed-element embolism of ophthalmic or cerebral arteries was demonstrated in all three patients. Embolic events occurred only in the territory of the symptomatic internal carotid artery. The average rate of cerebral embolization at transcranial Doppler ultrasonography was 4.1/hr, with a mean signal duration of 47 msec. No emboli were found in control subjects. CONCLUSIONS: The observed high frequency of silent embolism of the intracranial arteries detected by transcranial Doppler monitoring in patients with recurrently symptomatic extracranial carotid artery disease should encourage studies of the prognostic and therapeutic implications of this method.     

Intravascular streaming and variable delivery to brain following carotid artery infusions in the Sprague-Dawley rat

Intracarotid artery infusions in animals are commonly performed in studies of the blood-brain barrier and in chemotherapy trials. Implicit in the analysis of these experiments is that the infusate will be distributed to the territory of the internal carotid artery in a manner that is proportional to blood flow. Fifteen Sprague-Dawley rats were studied to determine if poor infusate mixing with blood due to intravascular streaming occurred during intracarotid artery drug infusions and if it could be eliminated with fast retrograde infusion. In three experimental groups, a radiolabeled flow tracer--14C-iodoantipyrine (IAP)--was infused retrograde through the external carotid artery into the common carotid artery at slow, medium, and fast rates (0.45, 1.5, and 5.0 ml/min). In a control group, IAP was injected intravenously (i.v.). Local isotope concentrations in the brain were determined by quantitative autoradiography, and the variability of isotope delivery was assessed in the frontoparietal cortex, temporal cortex, and caudate putamen of all animals. Streaming phenomena were manifest in all selected anatomic areas after the slow and medium rates of intraarterial infusion. After fast intracarotid infusion or i.v. injection, there was uniform distribution of isotope in the same brain regions.     

Gender-specific risk of perioperative complications in carotid endarterectomy patients with contralateral carotid artery stenosis or occlusion

Carotid endarterectomy (CEA) has been shown to be effective in stroke prevention in selected patients. Some studies, however, identified gender as an independent risk factor for perioperative CEA complications demonstrating an increased rate of perioperative stroke or death in women. Furthermore, contralateral internal carotid artery (ICA) occlusion has been associated with higher rates of perioperative CEA complications. Therefore, we sought to analyse the gender-specific risk of perioperative CEA complications between patients with or without contralateral ICA stenosis or occlusion. We retrospectively analysed 212 consecutive CEA patients (male = 156, Female = 56) for their gender-specific, perioperative risk of stroke, transient ischemic attack (TIA), restenosis and cardiac complications in the presence (62%) or absence (38%) of a contralateral ICA stenosis/occlusion. In women but not in men, risk of perioperative ischemic events (stroke, TIA) or re-stenosis (p = 0.036) and combined perioperative complications (ischemic events, re-stenosis or cardiac complications; 38.2 % vs. 9.1%; p = 0.028) was significantly increased in the presence of a contralateral ICA stenosis or occlusion. Furthermore, in the presence of a contralateral ICA stenosis/occlusion the number of perioperative ischemic events (p = 0.008) and combined perioperative complications (38.2 % vs. 14.3%; p = 0.006) was significantly higher in female than in male patients. Our study suggests that women with contralateral ICA stenosis or occlusion may have a significantly higher risk for perioperative CEA complications than other subgroups of CEA patients. This risk increase seems to be gender-specific and, if confirmed in larger prospective studies, may influence ICA stenosis therapy in the presence of a contralateral ICA stenosis/occlusion in female patients.     

Relationship between ophthalmic artery blood flow and recanalization of occluded carotid artery. Ultrasonic Doppler study

Ophthalmic artery blood flow in 5 patients with internal carotid artery occlusion of sudden onset was monitored by an ultrasonic Doppler flowmeter to investigate the possible relationship to spontaneous recanalization of the occluded artery. The occluded internal carotid arteries of 2 patients were confirmed angiographically to recanalize and the reversed flow of their ophthalmic arteries changed to physiological flow after the recanalization. The ophthalmic artery blood flow remained reversed in 2 patients whose occluded internal carotid arteries did not recanalize on the follow up angiograms. In the other patient, whose ophthalmic artery blood flow was not detected by the ultrasonic Doppler flowmeter in the acute stage, physiological flow through the ophthalmic artery was detected later. The occluded internal carotid artery did not recanalize and this physiological ophthalmic artery blood flow was filled through the circle of Willis.     

Internal carotid artery stent placement without emboli protection: results and long-term outcome

Patients with symptomatic > or = 60% (n = 134), asymptomatic > or = 80% (n = 143), and asymptomatic progressive > or = 60% (n = 25) internal carotid artery stenosis underwent stenting and were followed clinically and by Doppler-assisted duplex imaging for 27.1 +/- 15.6 months. Stroke and death from stroke occurred within 30 days after stenting in 4.7% of the symptomatic and in 3.0% of the asymptomatic patients and in the follow-up period in 2.3% of the symptomatic and in 1.2% of the asymptomatic patients.     

Detection of middle cerebral artery emboli during carotid endarterectomy using transcranial Doppler ultrasonography

The purpose of our study was to define the signal characteristics and clinical circumstances associated with emboli detected in the middle cerebral artery using 2-MHz pulsed transcranial Doppler ultrasound in patients undergoing carotid endarterectomy. Signals designating emboli were transients displaying harmonic qualities the signatures of which were clearly different from those of mechanical and electronic artifacts. We reviewed the audio/video tape recordings from 91 patients for signals of air bubble emboli occurring upon release of common carotid artery crossclamps; recordings from 35 patients (38%) demonstrated air bubble emboli. Transients with signatures identical to those of air bubble emboli were also discovered when bubbles in the bloodstream were improbable; we defined these transients as representing formed-element emboli. Such signals were found in recordings from 24 patients (26%), and they occurred before (both spontaneously and upon common carotid artery compression), during, and after surgical dissection. Signals indicating formed-element emboli were associated with intraluminal platelet thrombus, with ulcerations in the carotid artery, and with transient ischemic attacks or stroke. Most postoperative formed-element emboli did not cause symptoms but, when persisting for hours, they were associated with strokes and cerebral infarction. This Doppler ultrasound method of detecting emboli will be useful in the study of stroke mechanisms and as a clinical test to guide the medical and surgical treatment of patients at risk of stroke.     

Pharyngo-occipital artery variant arising proximal to occluded internal carotid artery: The risk of an unnecessary endarterectomy

Collateral branches originating from the cervical internal carotid artery (ICA) are rare but can have significant clinical and surgical implications. We present a case of pharyngo-occipital artery arising proximal from an occluded ICA that was missed and confused for severe stenosis of the ICA, leading to the misguided indication for carotid endarterectomy. Advanced preoperative studies allowed timely recognition of this anomaly and reconsideration of the therapeutic plan. We stress the importance of recognizing these variants by careful examination of multimodal pre-surgical exams. Awareness of these variants will allow a more precise diagnosis, and more appropriate management of patients with carotid artery disease.     

Evaluating brain tolerability to carotid artery occlusion

An objective and practicable method to evaluate the brain tolerance to unilateral carotid artery occlusion was attempted. Ten consecutive cases were studied. Endovascular trial balloon occlusion of the unilateral carotid artery in conjunction with single-photon emission computed tomography (SPECT) as well as digital subtraction angiography (DSA) and clinical neurological evaluation was routinely performed for those patients who might undergo permanent occlusion of the internal (ICA) and/or common carotid artery (CCA). The result of SPECT was analyzed semi-quantitatively and compared with the baseline data as well as the data from contralateral side. The relative symmetry index (rS) of side-to-side radioactivity counts relevant to the baseline was calculated. One subject failed the balloon occlusion test (BOT), even though an angiographically adequate collateral circulation was observed. The rS of the patient was 74.5%. The remaining patients passed the 45-min BOT without any neurological deficiency induced. Their value of rS was 97.8% +/- 4.4%. Based the BOT results, the left ICA, CCA and external carotid artery were excised in one patient, CCA-ICA reconstructions after carotid occlusions were performed in three. The carotid arteries were saved in five. For one patient, the ICA was occluded spontaneously during the BOT. There were no neurological impairments developed after the surgery. With this BOT technique, clinically silent areas of decreased perfusion might be detected. We suggest it be a routine preparatory to carotid manipulations.