Noninavasive angiography for the diagnosis of carotid artery disease using Doppler ultrasound (carotid artery Doppler)

To detect stenosis in the carotid artery with a bidirectional continuous-wave Doppler ultrasound device, the following noninvasive procedure, applied on 800 patients and compared with 249 angiograms of 186 patients, has proved to be about 90% reliable. Measurements of flow signals were taken over the terminal branches of the ophthalmic artery (supratrochlear and supraorbital arteries) and averaged. Compression of superficial temporal and facial arteries revealed flow direction and common carotid artery compression revealed the supplying blood vessel and the effectiveness of the circle of Willis. Measurements over the common carotid arteries were used to evaluate peripheral resistance. A set of eight criteria was used; the diagnostic value of each criterion was calculated by comparing 138 pathological Doppler findings in 123 patients with the angiograms. If reverse flow direction in supratrochlear or supraorbital artery was used alone, only 43% correct diagnoses would have resulted. A more severe stenosis is not necessarily correlated with a more weighted criterion; a subset of criteria is less efficient than the combination of all criteria. Application during 32 extracranial endarterectomies on 28 patients informed the surgeon immediately about the hemodynamic effect of the surgical intervention. Rethrombosis was diagnosed in two patients by postoperative Doppler examination.     

Diagnosis of disease of the common carotid artery bifurcation: CT angiography vs catheter angiography

OBJECTIVE: The purpose of this prospective study was to compare CT angiography with conventional catheter angiography for imaging the bifurcation of the common carotid artery in patients with signs and symptoms of atherosclerotic disease. SUBJECTS AND METHODS: Ten symptomatic patients (20 bifurcations of the common carotid artery) underwent contrast-enhanced spiral CT of the neck. The images were preprocessed and postprocessed by using a commercially available volume-rendering technique and a maximum-intensity-projection algorithm. All patients subsequently underwent conventional catheter angiography. RESULTS: CT angiographic findings matched those on conventional angiograms in only 50% of cases. Two nearly occluded internal carotid arteries were missed with CT angiography. Four internal carotid arteries were interpreted as occluded on the basis of CT angiograms but were shown as patent on catheter angiograms. Of five severe stenoses shown by CT angiography, only two were confirmed by conventional angiography. CONCLUSION: The results indicate that CT angiography as used in this study cannot replace catheter angiography. With CT angiography, both overestimation and underestimation of stenoses occur.     

CT angiography of the carotid artery

CT angiography shows promise as a noninvasive method to display carotid vascular pathology. This article discusses technique, stenosis measurements, pitfalls, strengths, and weaknesses of CT imaging of the carotid artery.     

Computed tomographic angiography for the evaluation of carotid artery stenosis

BACKGROUND AND PURPOSE: No previous study has compared the reliability of carotid artery measurement provided by axial images, shaded surface display (SSD), and maximum intensity projection (MIP). METHODS: Helical CT and conventional angiography were performed prospectively in 20 patients with atherosclerotic stenosis of the internal carotid artery. Stenosis measurement was performed in a blinded fashion on angiography and CT by two independent examiners. Calcifications were segmented when they were located far enough from the vascular lumen. SSD and MIP were systematically performed for each carotid bifurcation. We measured stenosis using conventional angiography as standard and the different CT reconstructions (axial images, SSD, and MIP) by comparing the stenosis diameter at its narrowest point to the normal internal carotid artery. The degree of stenosis was classified into six groups: no stenosis, mild stenosis (< 30%), moderate stenosis (30% to 70%), severe stenosis (> 70%), near occlusion, and occlusion (100%). No measurement was made in cases of normal artery, near occlusion, and occlusion. RESULTS: Correlations between angiography and the three types of reconstruction were very good. Axial sections correctly classified the carotid arteries in 95% of cases. In 10 carotid arteries, stenosis was not assessable by SSD and MIP because of calcifications. In the remaining carotid arteries, MIP correctly classified the degree of stenosis in 96% of cases, whereas SSD misclassified 21% of cases. CONCLUSIONS: Our study showed that axial images provide a reliable evaluation of carotid artery stenosis. Calcifications are limiting factors in SSD or MIP. When atherosclerotic plaques are not calcified, MIP reconstructions provide a more reliable measurement of the vascular lumen than SSD.     

Nonatheromatous carotid artery disease

Common and uncommon nonatheromatous diseases affecting the cervical carotid artery are discussed. Specifically, the radiographic and pertinent clinical features of cervical carotid artery congenital variants, dissection, fibromuscular dysplasia, Takayasu's arteritis, and infection are described. Catheter angiography continues to have an important role in the diagnosis of many of these conditions. Magnetic resonance imaging techniques are emerging as a useful adjunct to catheter angiography and occasionally may be the primary imaging modality for diagnosis.     

Predicting the effect of carotid artery occlusion during carotid endarterectomy: comparing transcranial doppler measurements and cerebral angiography

BACKGROUND and PURPOSE: We correlated the mean transcranial Doppler blood flow velocity (FVm) during carotid endarterectomy with the functional collateral pathway(s) documented by angiography. METHODS: Three patient groups were established: group 1 was dependent on the anterior communicating artery, group 2 on the anterior communicating artery and ipsilateral posterior communicating artery, and group 3 on the ipsilateral posterior communicating artery. Continuous middle cerebral artery FVm and electroencephalographic monitoring were performed in 45 patients during carotid endarterectomy. RESULTS: Clamped FVm was lowest in group 3 at 17+/-9 cm/s versus 36+/-16 and 33+/-11 cm/s for groups 1 and 2 (P<0.01). FVm values in groups 1 and 2 were similar. There was significant cerebral arterial vasodilation in group 3 patients on the basis of a pulsatility index of 0.38+/-0.15. The maximum FVm after clamp release was similar among the 3 groups. Normalized blood flow velocity 1 minute before release of the clamp was increased from the minimum flow velocity after clamping only in group 1 and 2 patients. CONCLUSIONS: The ipsilateral posterior communicating artery is a minor collateral pathway during acute carotid occlusion that contributes little to the collateral flow if there is a functional anterior communicating artery. Collateral flow through the middle cerebral artery is not recruited during occlusion in group 3 patients. The reperfusion FVm transient is independent of the primary collateral pathway. Documentation of functional collateral pathways on the basis of Doppler or angiographic examination may be advantageous in future studies since it can provide the basis for comparison among studies.     

High-resolution magnetic resonance angiography of the internal carotid artery: 2D vs 3D TOF in stenotic disease

The aim of this study was to compare high-resolution 2D TOF with high-resolution 3D TOF in the study of internal carotid artery disease. Sixty-four patients with clinical signs of cerebrovascular insufficiency were studied with a superconductive 1.5 T magnet using two techniques: 2D and 3D TOF. Digital subtraction angiography (DSA) was the gold standard. The 2D TOF technique was performed using the following parameters: TR/TE/FA/MA 49 ms/9 ms/60 degrees/512 x 256; the 3D TOF was performed with the following parameters: TR/TE/FA/MA 50 ms/8 ms/20 degrees/512 x 256. The 2D TOF agreed with DSA in 116 of 128 diagnostic judgments (90%) and overestimated seven times. The 3D TOF technique agreed with DSA in 125 of 128 diagnostic judgments (97%) with one overestimation and two underestimations. There was no statistically significant difference (P < 0.05) between the two different techniques. Our study confirms the high reliability of the methodology carried out with the high-resolution 2D and 3D technique.     

Common carotid artery bifurcation: preliminary results of CT angiography and color-coded duplex sonography compared with digital subtraction angiography

Ischemia/reperfusion (I/R) injury to the intestinal mucosa occurs in several commonly encountered clinical situations, such as necrotizing enterocolitis and nonocclusive mesenteric insufficiency. No clinically feasible technique is available for mucosal preservation during ischemia. The goal of this work was to determine whether the continuous intraluminal flow of oxygenated perfluorocarbon (PFC) could protect mucosal integrity and function in a rat model of intestinal I/R injury. Rats were subjected to ischemia by clipping the superior mesenteric artery (SMA) for 60 minutes. Reperfusion was achieved by release of the clip for 120 minutes. Animals were divided into 4 groups: Sham (laparotomy alone), I/R (I/R alone), I + PFC/R (PFC was administered during the ischemic interval only), I/R + PFC (PFC was delivered only during reperfusion). Tissue sections were examined blindly to assess mucosal integrity, and mucosal dissacharidase activities were measured to assess function. Oxygenated PFC, when administered during ischemia alone, ameliorated I/R-induced mucosal injury; however, when it was delivered during reperfusion alone, the mucosal injury worsened. When oxygenated PFC was administered throughout I/R, the degree of mucosal injury was similar to the I + PFC/R group, and dissacharidase activities were preserved when compared with the I/R group. Intraluminal perfusion of oxygenated PFC during ischemia preserves mucosal function and integrity, and may offer a new treatment modality for a variety of mesenteric ischemic disorders.     

Magnetic resonance angiography demonstrates vascular healing of carotid and vertebral artery dissections

BACKGROUND AND PURPOSE: Dissection of the carotid and vertebral arteries is most accurately diagnosed with conventional angiography. MR techniques are sensitive for detecting the abnormalities associated with dissection but may lack specificity. We hypothesized that MR may be useful for serial monitoring of dissection and may therefore guide therapy. METHODS: All patients with angiographically proven carotid and/or vertebral artery dissection from July 1994 to June 1996 were followed for a median duration of 10.5 months. Of these 29 patients (44 vessels), 18 were concurrently evaluated with MR, and a target group of 9 patients (17 vessels) was prospectively followed with MR at 3-month intervals. RESULTS: In the 18 patients with both imaging studies at baseline, angiography revealed 30 dissected vessels while MR detected 27 (90%). In the target group of 9 patients, initial MR identified 15 of the 17 dissections diagnosed with angiography. Serial MR revealed complete healing in 5 vessels, improvement in 6 vessels, no change in 4 vessels, and worsening in 2 vessels. The radiographic features most likely to resolve were stenosis and mural hematoma, while occlusion and luminal irregularity tended to persist. Late ischemic events occurred in 2 patients, both with persistent MR evidence of dissection, one while subtherapeutic on warfarin therapy and the other occurring 1 week after warfarin was discontinued. CONCLUSIONS: MR is a reliable noninvasive method for following the vascular response to treatment and may guide the course of a clinical trial comparing medical therapies for carotid and vertebral artery dissection.     

Prevalence of extracranial carotid and vertebral artery disease in Chinese patients with coronary artery disease

Electrotonic responses recorded extra- or intracellularly from peripheral nerve preparations show a "sag" to hyperpolarizing current pulses. The biophysical nature of this "inward rectification" is still under discussion since the phenomenon has not been noted at voltage-clamped single nerve fibres, and since Cs+, which reduces inward rectification, is not a specific ion channel blocker. In this study, we found that low micromolar concentrations of ZD 7288, a specific blocker of the hyperpolarization-activated cationic current (Ih) in the soma of central mammalian neurons, result in a complete block of inward rectification in the electrotonic responses of isolated rat spinal dorsal roots. In addition, ZD 7288 enhanced the activity-dependent slowing of conduction seen in compound C fibre action potentials of isolated rat vagus nerves and augmented the post-tetanic hyperpolarization following trains of action potentials in unmyelinated and myelinated axons. The data suggest that ZD 7288 is a potent blocker and a useful research tool for the study of hyperpolarization-activated inward rectification (Ih) of peripheral nerve preparations.     

Prognostic assessment in coronary artery disease: role of radionuclide angiography

Left ventricular function is one of the most important determinants, if not the most important determinant, of outcome in patients with coronary artery disease. The ability of radionuclide angiography to assess resting and exercise ejection fraction accurately and reproducibly has been shown to be a critical determinant of survival in large-scale studies of survivors of myocardial infarction, as well as patients with chronic stable angina. In addition, several centers have demonstrated that the exercise ejection fraction is an extremely valuable (and perhaps the most valuable) noninvasive parameter in predicting survival among patients with coronary artery disease. The prognostic insights gained from the exercise ejection fraction add incremental predictive information to the coronary anatomic information obtained from coronary arteriography, especially in patients with multivessel disease and those with left ventricular dysfunction at rest.     

The natural history of asymptomatic carotid artery disease

PURPOSE: The purpose of this article is to determine the natural history of carotid artery disease among asymptomatic patients with cervical bruits or other risk factors for stroke and to study the value of duplex ultrasonography in predicting future neurologic events. METHODS: Two hundred forty-two asymptomatic, unoperated patients, referred for evaluation of asymptomatic carotid artery disease, were followed prospectively with duplex ultrasonography. RESULTS: Fifteen ischemic strokes (6.2%) and 20 transient ischemic attacks (TIA) (8.3%) occurred in 34 patients during a mean follow-up of 27.4 months. Annual stroke, TIA, and combined event rates were 2.7%, 3.6%, and 6.2%, respectively. Although patients with 80% to 99% lesions had a 20.6% annual event rate, most events occurred contralateral to these lesions; the vessel-specific annual event rate for 80% to 99% disease was 5.1%. Only one of 15 strokes occurred ipsilateral to an 80% to 99% stenosis. Echolucent plaques were associated with TIA and stroke (5.7% annual vessel event rate vs 2.4% for echogenic plaques, p = 0.03). Disease progression was highly correlated with TIA and stroke (p < 0.0001), but it usually occurred in association with rather than before ischemic events, thus proving more useful in explaining pathogenesis than in predicting future events. There was no association between aspirin use and TIA, but patients taking aspirin had a threefold higher annual stroke rate (1.6% vs 4.8%, p = 0.027). CONCLUSIONS: This study, while confirming significant risk for asymptomatic patients with critical stenosis or echolucent plaque, demonstrates the importance of contralateral disease and the absence of orderly progression from minimal disease through high-grade stenosis to symptomatic cerebral ischemia. TIA and stroke commonly occur in association with abrupt, unpredictable, quantum changes in carotid artery disease.     

Early results of combined carotid endarterectomy and coronary artery bypass grafting in patients with severe coronary and carotid artery disease

The management of patients with carotid artery disease who require coronary artery bypass grafting (CABG) remains controversial. Several published series from the USA (including one with prospective randomization) advocate a combined approach of carotid endarterectomy (CEA) followed immediately by coronary artery bypass surgery. However, experience of combined carotid endarterectomy and coronary bypass grafting has not been previously reported by a centre from the United Kingdom. Between 1986 and 1991 we performed this combined procedure on 18 patients who required myocardial revascularization and had co-existing severe (> 70%) carotid stenosis. Sixteen patients (89%) had angina and 11 patients (61%) had symptomatic carotid artery disease. The perioperative mortality was 5.5% and the ipsilateral perioperative stroke rate was 5.5%. These early results are encouraging and suggest that further evaluation of combined carotid endarterectomy and coronary artery bypass surgery is warranted.     

A surgical approach to coexistent coronary and carotid artery disease

OBJECTIVE: To assess the early results of combined coronary artery bypass graft surgery and carotid endarterectomy. DESIGN: Retrospective and ongoing analysis of patients who underwent combined coronary artery bypass graft surgery and carotid endarterectomy. SETTING: Cardiothoracic unit in a London teaching hospital. PATIENTS: From June 1987 to March 1995, 64 patients were identified. They were patients who were scheduled to have coronary artery bypass graft surgery or required urgent coronary revascularisation and who were found to have significant coexistent carotid disease. (Unilateral carotid stenosis > 70%, bilateral carotid stenosis > 50%, or unilateral carotid stenosis > 50% with contralateral occlusion.) INTERVENTIONS: Both procedures were performed during one anaesthesia: the carotid endarterectomy was performed first without cardiopulmonary bypass. After completion of carotid endarterectomy, coronary artery bypass graft surgery was performed. MAIN OUTCOME MEASURES: The incidence of stroke, transient ischaemic attack, and myocardial infarction in the early postoperative period was analysed. RESULTS: Myocardial revascularisation was successful in all 64 patients. There were no perioperative infarcts. In three patients (4.7%) a new neurological deficit developed postoperatively: two recovered fully before hospital discharge. CONCLUSIONS: Combined coronary artery bypass graft surgery and carotid endarterectomy were performed safely and with good results.     

Asymptomatic carotid artery bifurcation disease in patients with claudication

Deep vein thrombosis may occur in the axillary or subclavian veins in the upper extremities, sometimes in young patients without the typical risk factors for thrombus development. This unusual clinical situation usually follows strenuous activity and is often referred to as "effort" thrombosis. Since some cases have occurred with mild exertion and there is a lack of obvious predisposing vessel trauma, a more correct term might be "primary" thrombosis. Early recognition of this condition is necessary to prevent potentially fatal acute effects and minimize chronic sequelae.     

Rotational digital subtraction carotid angiography: technique and comparison with static digital subtraction angiography

To compare the efficiency of sperm preparation between the two-layer Percoll gradient and mini-Percoll methods, 50 normal and 33 abnormal semen samples from male partners of infertile couples were studied. The number of recovered spermatozoa, percentage of motility, percentage of normal morphology, and their survival at 24 and 48 hours were assessed. Both Percoll gradient techniques resulted in a significantly higher percentage of motility and percentage of normal morphology compared with the original semen samples (p < 0.0001). The two-layer Percoll gradient showed a higher sperm recovery than the mini-Percoll method (p < 0.001), but the latter resulted in a higher percentage of motility (p > 0.001) and a higher sperm survival rate at 24 hours (p < 0.05) than the former, regarding normal semen samples. These differences did not appear with abnormal semen samples when analyzed as a group. Considering each of the abnormal parameters separately, sperm recovery was significantly higher after the two-layer Percoll gradient in the case of astheno- and teratozoospermia (p < 0.05), but sperm survival at 48 hours was higher after the mini-Percoll gradient in the case of teratozoospermia (p < 0.05). It is concluded that both the two-layer Percoll gradient and mini-Percoll method can be used effectively for sperm preparation. The former yields a higher sperm recovery, but the latter should be considered regarding teratozoospermic samples and semen samples of very low volume.     

Elective stenting of carotid artery stenosis in patients with severe coronary artery disease

AIMS: To evaluate the feasibility and safety of elective carotid stent implantation in patients with carotid stenoses and concomitant coronary artery disease, as an alternative to combined carotid and coronary surgery. METHODS: We treated 50 patients with >70%, stenoses in 53 carotid arteries with balloon angioplasty followed by elective stent implantation. All patients had severe coronary artery disease, and/or mitral insufficiency, aortic stenosis, rhythm disorders or generalized arteriosclerosis. In three patients the opposite carotid artery was occluded; nine patients had bilateral stenoses of which two received stents bilaterally. RESULTS: Fifty-six successful stent implantations (42 Wallstents, eight BeStents, two AVE-Microstents, one Palmaz Schatz stent, three Sito stents) were performed, reducing the baseline percent stenosis from 78 +/- 18%, to 13 +/- 11%. Complications included three transient ischaemic attacks, one minor and one major stroke. Follow-up was available for 46 patients over a mean of 10 months. Three asymptomatic restenoses and one deformation of a BeStent occurred. CONCLUSION: Our preliminary results indicate that carotid artery stenting in patients with concomitant severe coronary artery disease is feasible, safe, and may be an alternative to combined carotid and coronary surgery.     

Noninvasive angiography for the diagnosis of vertebral artery disease using Doppler ultrasound (vertebral artery Doppler)

A transoral noninvasive procedure in the oropharynx using local anesthesia was applied to detect flow in the vertebral arteries with a bidirectional continuous-wave Doppler ultrasound system. Common carotid artery compression was used to identify the vertebral artery. Flow direction, amplitude of flow signals, diastolic flow, and reaction of flow on common carotid artery compression served as diagnostic parameters. The procedure was applied in 90 patients of whom 42 underwent angiography. The method has proved to be 82% accurate. It was most reliable in the diagnosis of occlusion or aplasia, subclavian steal and normalcy, and was less reliable in the detection of stenosis or hypoplasia of a vertebral artery. Eleven patients with subclavin steal, five patients with a missing vertebral artery three patients with hypoplasia or stenosis, and 15 patients with normal angiorgraphical findings were correctly diagnosed by Doppler; normal Doppler findings were present in three patients with a mission or stenosed vertebral artery. Those patients (five) with Doppler indications of subclavian steal (one patient), missing vertebral artery (two patients), or stenosis (two patients) had normal angiograms. Application of the Doppler procedure, after 11 subclavin endarterectomies, informed the surgeon immediately about the hemodynamic effect of surgical intervention. Rethrombosis was diagnosed in two patients by postoperative Doppler examination.