Assay of phospholipase D activity in cell-free systems

Phospholipase D (PLD) enzymes are present in all animal and plant species and have been linked to many critical cellular processes, including proliferation, differentiation, motility, and secretion. The functional significance of PLD derives from its generation of phosphatidic acid, which has both direct signaling properties via activation of numerous kinases, phosphatases, phopspholipases, and other enzymes, as well as via its conversion to diglycerides, the endogenous activators of protein kinase C. The two mammalian PLD isoforms, PLD1 and PLD2, are peripheral membrane proteins that exhibit important physical and functional interactions with the actin cytoskeleton. We outline a cell-free system for the characterization of mammalian PLDs and their activation by physiologic stimuli or pharmacologic agonists for guanine triphosphate-binding proteins. This assay system is used to illustrate the interactions of PLD1 with specific membrane domains and their associated filamentous and monomeric actin components.

Phospholipase D1 Regulates Phagocyte Adhesion

Adhesion is a fundamental cellular response that is essential to the physiologic processes of development, differentiation, proliferation, and motility, as well as to the pathology of inflammation, transformation, and metastasis. Adhesion of phagocytic leukocytes is a critical modulator of antimicrobial and cytotoxic functions, including the respiratory burst, secretion, and apoptosis. Because phospholipase D (PLD) is linked to several signaling pathways implicated in these processes, we tested the hypothesis that PLD regulates phagocyte adhesion. Adhesion of primary human neutrophils and monocyte-derived macrophages to fibronectin was accompanied by marked stimulation of PLD activity. Similarly, adhesion of both human (PLB, THP-1) and murine (RAW) myeloid-macrophage cell lines to fibronectin, fibrinogen, collagen, or plastic resulted in significant activation of PLD. Stimulation of PLD activity was rapid and persisted for at least 90 min. Confocal microscopy indicated that PLD1 exhibited partial colocalization with actin filaments at the adherent interface, in proximity to the focal adhesion protein, paxillin. Reductions in PLD activity by chemical inhibitors or specific short-interfering RNA-induced knockdown of PLD1 resulted in significant inhibition of phagocyte adhesion and was accompanied by reductions in total cellular F-actin. These data support the hypotheses that adhesion stimulates PLD activity, and that PLD1 regulates the initial stages of phagocyte adhesion. Stimulation of PLD activity may promote adhesion-dependent phagocyte effector responses.

Botulinum toxin A during pregnancy: a survey of treating physicians

Botulinum toxin A (btxA) is widely used for cosmetic purposes, headaches, dystonia, spasticity, pain and other on and off label uses. Despite the widespread use of btxA in women of childbearing potential, there are few data on the effects of this drug on pregnant women and the fetus. The goal of this study was to survey physicians who use btxA, to determine their experience with pregnant women. We surveyed 900 physicians who used commercially available btxA. The questionnaire asked treating physicians if they had knowingly or unknowingly injected pregnant women and what was the outcome of each pregnancy. In total, 396 physicians (44%) returned questionnaires, of whom only 12 physicians reported injecting pregnant women with btxA. Sixteen pregnant women were injected, mostly in the first trimester, and only one patient, who had prior spontaneous abortions, suffered a miscarriage. Another woman had a therapeutic abortion. All other pregnancies went to term and there were no fetal malformations. Based on this limited survey of treating physicians in the USA, btxA appears to be relatively safe for both expectant mother and fetus. We need further data, however, and we would recommend that physicians and patients carefully consider the risks and benefits before using btxA in pregnant women.

Effects of peanut oil consumption on appetite and food choice

OBJECTIVE

Peanut consumption may improve lipid profiles without promoting weight gain. Both properties have been attributed to their high-unsaturated fat content. Mono and polyunsaturated fatty acids reportedly hold stronger satiety value than saturated fats and may help appetite control. This study investigated the effects of chronic peanut oil consumption on appetite and food choice.

RESEARCH METHODS AND PROCEDURES

A total of 129 healthy adults from three countries (Brazil, Ghana and US) were randomly assigned to one of four treatment arms: consumption of peanut oil, olive oil or safflower oil as 30% of individual resting energy expenditure (REE) for 8 weeks or no dietary intervention. Participants received no other dietary guidance. They completed appetite questionnaires eliciting information about hunger, fullness, desire to eat, and prospective consumption during all waking hours for 1 day at weeks 2 and 6 and for 1 or 3 days at weeks 0, 4 and 8. Diet records were completed at weeks 0, 4 and 8.

RESULTS

No differences in appetitive ratings were observed over the 8-week trial. There were no significant treatment by time interactions. Total caloric intake was significantly higher at week 8 relative to baseline (F=10.08, P<0.05). The increases for each treatment were: peanut oil=197+/-114; olive oil=237+/-121; safflower oil=274+/-90; control=75+/-71. Free-feeding intake, an index of dietary compensation, was reduced significantly at weeks 4 and 8 compared to baseline (F=9.08, P<0.00). The declines (compensation scores) were (kcals): peanut oil=-208+/-105 (46%); olive oil=-235+/-105 (50%); safflower oil=-186+/-102 (44%). There were no significant differences across countries in appetite ratings.

DISCUSSION

A prior intervention with whole peanuts reported a dietary compensation score of 66% over 8 weeks, this compares to a 46% compensation score observed with peanut oil. Our data suggests that the lipid fraction in peanuts elicits a weak effect on satiety.

Sphingosine Kinase 1 (SK1) Is Recruited to Nascent Phagosomes in Human Macrophages: Inhibition of SK1 Translocation by Mycobacterium tuberculosis

Mycobacterium tuberculosis (M.tb) is a leading cause of global infectious mortality. The pathogenesis of tuberculosis involves inhibition of phagosome maturation, leading to survival of M.tb within human macrophages. A key determinant is M.tb-induced inhibition of macrophage sphingosine kinase (SK) activity, which normally induces Ca2+ signaling and phagosome maturation. Our objective was to determine the spatial localization of SK during phagocytosis and its inhibition by M.tb. Stimulation of SK activity by killed M.tb, live Staphylococcus aureus, or latex beads was associated with translocation of cytosolic SK1 to the phagosome membrane. In contrast, SK1 did not associate with phagosomes containing live M.tb. To characterize the mechanism of phagosomal translocation, live cell confocal microscopy was used to compare the localization of wild-type SK1, catalytically inactive SK1G82D, and a phosphorylation-defective mutant that does not undergo plasma membrane translocation (SK1S225A). The magnitude and kinetics of translocation of SK1G82D and SK1S225A to latex bead phagosomes were indistinguishable from those of wild-type SK1, indicating that novel determinants regulate the association of SK1 with nascent phagosomes. These data are consistent with a model in which M.tb inhibits both the activation and phagosomal translocation of SK1 to block the localized Ca2+ transients required for phagosome maturation.

Carotid artery stenting for the high surgical risk patients

Obstructive atherosclerotic carotid bifurcation disease is responsible for approximately 30% of stroke cases in the United States. Any successful treatment of this disease should demonstrate significant and durable reduction in the related risk for stroke without compromising the patient safety. The indications for CAS are evolving as the techniques, the stents and catheter technology advance. There is an ongoing need to improve the equipment suitable for carotid stenting and a need to enhance the safety of the procedure. Often, when a technical problem is encountered, it is attributed to the inadequacy of the devices currently available. As the technology improves, particularly with the application of the anti-embolization devices, the indications and contraindication may need to be revised.

Phospholipases D1 and D2 Coordinately Regulate Macrophage Phagocytosis

Phagocytosis is a fundamental feature of the innate immune system, required for antimicrobial defense, resolution of inflammation, and tissue remodeling. Furthermore, phagocytosis is coupled to a diverse range of cytotoxic effector mechanisms, including the respiratory burst, secretion of inflammatory mediators and Ag presentation. Phospholipase D (PLD) has been linked to the regulation of phagocytosis and subsequent effector responses, but the identity of the PLD isoform(s) involved and the molecular mechanisms of activation are unknown. We used primary human macrophages and human THP-1 promonocytes to characterize the role of PLD in phagocytosis. Macrophages, THP-1 cells, and other human myelomonocytic cells expressed both PLD1 and PLD2 proteins. Phagocytosis of complement-opsonized zymosan was associated with stimulation of the activity of both PLD1 and PLD2, as demonstrated by a novel immunoprecipitation-in vitro PLD assay. Transfection of dominant-negative PLD1 or PLD2 each inhibited the extent of phagocytosis (by 55-65%), and their combined effects were additive (reduction of 91%). PLD1 and PLD2 exhibited distinct localizations in resting macrophages and those undergoing phagocytosis, and only PLD1 localized to the phagosome membrane. The COS-7 monkey fibroblast cell line, which has been used as a heterologous system for the analysis of receptor-mediated phagocytosis, expressed PLD2 but not PLD1. These data support a model in which macrophage phagocytosis is coordinately regulated by both PLD1 and PLD2, with isoform-specific localization. Human myelomonocytic cell lines accurately model PLD-dependent signal transduction events required for phagocytosis, but the heterologous COS cell system does not.

Phenazine-1-carboxylic acid, a secondary metabolite of Pseudomonas aeruginosa, alters expression of immunomodulatory proteins by human airway epithelial cells

Pseudomonas aeruginosa is a gram-negative bacterium that causes both acute and chronic lung disease in susceptible patient populations. P. aeruginosa secretes numerous proteins and secondary metabolites, many of which have biological effects that likely contribute to disease pathogenesis. An unidentified small-molecular-weight factor was previously reported to increase IL-8 release both in vitro and in vivo. To identify this factor, we subjected the <3-kDa fraction from P. aeruginosa-conditioned medium to HPLC analysis. A peak fraction that stimulated IL-8 release was found by mass spectrometry to have a molecular mass (MM) of 224 Da. On the basis of this MM and other biochemical properties, we hypothesized that the factor was phenazine-1-carboxylic acid (PCA). Subsequent studies and comparison with purified PCA confirmed this hypothesis. Purified PCA exhibited a number of biological effects in human airway epithelial cells, including increasing IL-8 release and ICAM-1 expression, as well as decreasing RANTES and monocyte chemoattractant protein-1 (MCP-1) release. PCA also increased intracellular oxidant formation as measured by electron paramagnetic resonance and by an intracellular oxidant-sensitive probe. Antioxidants inhibited PCA-dependent increases in IL-8 and ICAM-1, suggesting that oxidants contributed to these effects. However, in contrast to the related phenazine compound pyocyanin, PCA did not oxidize NAD(P)H at physiologically relevant pH, providing preliminary evidence that PCA and pyocyanin may have distinct redox chemistries within the cell. Thus PCA is a biologically active factor secreted by P. aeruginosa that has several activities that could alter the host immune and inflammatory response and thereby contribute to bacterial disease pathogenesis.

Evolutionary conservation of physical and functional interactions between phospholipase D and actin

Phospholipase D (PLD) enzymes from bacteria to mammals exhibit a highly conserved core structure and catalytic mechanism, but whether protein-protein interactions exhibit similar commonality is unknown. Our objective was to determine whether the physical and functional interactions of mammalian PLDs with actin are evolutionarily conserved among bacterial and plant PLDs. Highly purified bacterial and plant PLDs cosedimented with mammalian skeletal muscle alpha-actin, indicating direct interaction with F-actin. The binding of bacterial PLD to G-actin exhibited two affinity states, with dissociation constants of 1.13 pM and 0.58 microM. The effects of actin on the activities of bacterial and plant PLDs were polymerization dependent; monomeric G-actin inhibited PLD activity, whereas polymerized F-actin augmented PLD activity. Actin modulation of bacterial and plant PLDs demonstrated kinetic characteristics, efficacies, and potencies similar to those of human PLD1. Thus, physical and functional interactions between PLD and actin in PLD family members from bacteria to mammals are highly conserved throughout evolution.

Cutting edge: Mycobacterium tuberculosis blocks Ca2+ signaling and phagosome maturation in human macrophages via specific inhibition of sphingosine kinase

One-third of the world's population is infected with Mycobacterium tuberculosis (Mtb), and three million people die of tuberculosis each year. Following its ingestion by macrophages (MPs), Mtb inhibits the maturation of its phagosome, preventing progression to a bactericidal phagolysosome. Phagocytosis of Mtb is uncoupled from the elevation in MP cytosolic Ca(2+) that normally accompanies microbial ingestion, resulting in inhibition of phagosome-lysosome fusion and increased intracellular viability. This study demonstrates that the mechanism responsible for this failure of Ca(2+)-dependent phagosome maturation involves mycobacterial inhibition of MP sphingosine kinase. Thus, inhibition of sphingosine kinase directly contributes to survival of Mtb within human MPs and represents a novel molecular mechanism of pathogenesis.

Regulation of phospholipase D activity by actin. Actin exerts bidirectional modulation of Mammalian phospholipase D activity in a polymerization-dependent, isoform-specific manner

Many critical cellular processes, including proliferation, vesicle trafficking, and secretion, are regulated by both phospholipase D (PLD) and the actin microfilament system. Stimulation of human PLD1 results in its association with the detergent-insoluble actin cytoskeleton, but the molecular mechanisms and functional consequences of PLD-actin interactions remain incompletely defined. Biochemical and pharmacologic modulation of actin polymerization resulted in complex bidirectional effects on PLD activity, both in vitro and in vivo. Highly purified G-actin inhibited basal and stimulated PLD activity, whereas F-actin produced the opposite effects. Actin-induced modulation of PLD activity was independent of the activating stimulus. The efficacy and potency of the effects of actin were isoform-specific but broadly conserved among actin family members. Human betagamma-actin was only 45% as potent and 40% as efficacious as rabbit skeletal muscle alpha-actin, whereas its inhibitory profile was similar to the single actin species from the yeast, Saccharomyces cerevisiae. Use of actin polymerization-specific reagents indicated that PLD1 binds both monomeric G-actin, as well as actin filaments. These data are consistent with a model in which the physical state of the actin cytoskeleton is a critical determinant of its regulation of PLD activity.

Microembolization during carotid stenting with the distal-balloon antiemboli system

BACKGROUND

The distal-balloon protection system is being evaluated for its efficacy in preventing embolic neurological events during carotid stenting (CAS). We sought to determine the effect of this system on the frequency of the Doppler-detected microembolic signals (MES) during CAS.

METHODS

Using transcranial Doppler, we compared the frequency of MES during CAS in 2 groups; 39 patients without distal protection and 37 with the distal-balloon protection system (GuardWire, Percusurge, Sunnyville, CA). There was no significant difference in the clinical or angiographic characteristics between the 2 groups. Three phases with increased MES counts were identified during the unprotected CAS; stent deployment, predilation, and postdilation (mean+/-SD: 75+/-57, 32+/-36, and 27+/-25, respectively).

RESULTS

The distal-balloon protection significantly reduced the frequency of MES during CAS (MES-counts: 164+/-108 in the control vs 68+/-83 in the protection group, p=0.002) particularly during these 3 phases. MES in the protection group were detected predominantly during sheath placement, guidewire manipulation and during the distal-balloon deflation.

CONCLUSIONS

Three phases with increased MES counts were identified during the unprotected CAS, e.g. stent deployment, predilation and postdilation. The distal-balloon protection system significantly reduced the frequency of MES during CAS, particularly during these 3 phases.

Carotid stenting with distal-balloon protection via the transbrachial approach

PURPOSE

To document the feasibility of brachial artery access for carotid stenting with distal-balloon protection of the internal carotid artery (ICA).

TECHNIQUE

Via percutaneous access to the brachial artery, a large double-curve catheter is advanced into the aortic arch over a hydrophilic guidewire to cannulate the left common carotid artery. Following sheath exchange, a GuardWire distal-protection balloon is positioned within the left ICA distal to the stenosis. The lesion is dilated, followed by deployment and dilation of a self-expanding stent. Transcranial Doppler monitoring shows only scarce microembolic signals during the procedure.

CONCLUSIONS

Carotid stenting with distal balloon protection via the brachial artery appears feasible as an alternative to standard femoral access.

Subarachnoidal hemorrhage following carotid stenting with the distal-balloon protection

A 61-year-old man underwent carotid stenting with the distal-balloon protection system for symptomatic carotid artery stenosis. During the procedure, progressive elevation of the systolic blood pressure occurred, reaching a peak of 220 mm Hg immediately following deflation of the distal balloon. This was associated with severe headaches and progressive deterioration in the mental status to a coma. Head CT scan showed massive subarachnoidal hemorrhage contralateral to the stented side and a secondary intracerebral hemorrhage. Despite immediate successful blood pressure control, his condition deteriorated and he died 2 days later.

Effect of the distal-balloon protection system on microembolization during carotid stenting

BACKGROUND

The distal-balloon protection system is being evaluated for its efficacy in preventing embolic neurological events during carotid stenting (CAS). We sought to determine the effect of this system on the frequency of Doppler-detected microembolic signals (MES) during CAS.

METHODS AND RESULTS

Using transcranial Doppler, we compared the frequency of MES during CAS in 2 groups: 39 patients without distal protection and 37 who used the distal-balloon protection system (GuardWire). There were no significant differences in the clinical or angiographic characteristics between the 2 groups. Three phases with increased MES counts were identified during unprotected CAS; these were stent deployment, predilation, and postdilation (75+/-57, 32+/-36, and 27+/-25 METS, respectively). The distal-balloon protection significantly reduced the frequency of MES during CAS (MES counts: 164+/-108 in the control versus 68+/-83 in the protection group; P=0.002), particularly during these 3 phases. MES in the protection group were detected predominantly during sheath placement, guidewire manipulation, and distal-balloon deflation.

CONCLUSION

Three phases with increased MES counts were identified during unprotected CAS (eg, stent deployment, predilation, and postdilation). The distal-balloon protection system significantly reduced the frequency of MES during CAS, particularly during these 3 phases.

Procedural safety and short-term outcome of ambulatory carotid stenting

BACKGROUND AND PURPOSE

Ambulatory procedures increase patient comfort and enhance cost-effectiveness. We sought to determine the feasibility and safety of ambulatory carotid stenting.

METHODS

A selected group of patients was admitted and discharged the same day after the carotid stenting procedure. Immediate and short-term outcomes are reported.

RESULTS

A total of 98 ambulatory carotid stenting procedures (98 hemispheres in 92 patients) were performed. There were 66 men (72%), and the mean age was 70+/-9 years. Of the patients, 28% had neurological symptoms related to the treated artery within 3 months before the procedure. Sixteen percent of the patients had prior carotid endarterectomy, 4% had prior ipsilateral neck radiation, and 8% had complete occlusion of the contralateral internal carotid artery. Successful access site hemostasis was ensured in all patients with suture-mediated vascular closure devices in 96 (98%) and manual compression in 2. Clinical follow-up was available for 96% of the patients at a mean time of 6+/-4 months. There were no neurological events, deaths, repeated procedures, or major access site complications.

CONCLUSIONS

Ambulatory carotid stenting is both safe and feasible. This approach will enhance the applicability of the procedure by increasing patient comfort and potentially reducing procedural costs.

Mycobacterium tuberculosis phagosomes exhibit altered calmodulin-dependent signal transduction: contribution to inhibition of phagosome-lysosome fusion and intracellular survival in human macrophages

Mycobacterium tuberculosis successfully parasitizes macrophages by disrupting the maturation of its phagosome, creating an intracellular compartment with endosomal rather than lysosomal characteristics. We have recently demonstrated that live M. tuberculosis infect human macrophages in the absence of an increase in cytosolic Ca(2+) ([Ca(2+)](c)), which correlates with inhibition of phagosome-lysosome fusion and intracellular viability. In contrast, killed M. tuberculosis induces an elevation in [Ca(2+)](c) that is coupled to phagosome-lysosome fusion. We tested the hypothesis that defective activation of the Ca(2+)-dependent effector proteins calmodulin (CaM) and CaM-dependent protein kinase II (CaMKII) contributes to the intracellular pathogenesis of tuberculosis. Phagosomes containing live M. tuberculosis exhibited decreased levels of CaM and the activated form of CaMKII compared with phagosomes encompassing killed tubercle bacilli. Furthermore, ionophore-induced elevations in [Ca(2+)](c) resulted in recruitment of CaM and activation of CaMKII on phagosomes containing live M. tuberculosis. Specific inhibitors of CaM or CaMKII blocked Ca(2+) ionophore-induced phagosomal maturation and enhanced the bacilli's intracellular viability. These results demonstrate a novel role for CaM and CaMKII in the regulation of phagosome-lysosome fusion and suggest that defective activation of these Ca(2+)-activated signaling components contributes to the successful parasitism of human macrophages by M. tuberculosis.

Carotid angioplasty with stenting in post-carotid endarterectomy restenosis

Recurrent stenosis post-carotid endarterectomy (CEA) is not a solitary or unusual phenomenon. Compared to the initial CEA, the reoperation is often more technically challenging and frequently results in local and neurological complications. Carotid artery angioplasty with stenting (CAS) is currently being investigated as an alternative to carotid endarterectomy. In our study, ninety-nine patients underwent CAS in 110 arteries. Procedural success was 99% (109/110). Our results show that CAS treatment in post-CEA restenosis, especially with improved technique and distal protection, is safe with a low neurological complication rate, without any "local" complications and without any cranial nerve palsies. This study suggests that the future primary mode of treatment of post-CEA restenosis might be carotid stenting rather than surgery.

Integrated minimally invasive approaches for the treatment of atherosclerotic vascular diseases: Hybrid procedures

Patients may develop simultaneous symptoms of atherosclerotic vascular disease from different arterial beds. A concurrent minimally invasive approach to the management of these clinical situations may be an advantage over conventional surgical procedures. This study describes two separate case series of patients undergoing coronary/peripheral (n = 38) and peripheral/peripheral procedures (n = 10). Technical and clinical success was achieved in all patients. There were two periprocedural complications (retroperitoneal bleed and septicemia) in the coronary/peripheral series and no complications in the peripheral/peripheral series. We also present five case reports to illustrate the utility of hybrid procedures in various clinical settings. This study suggests that the use of simultaneous or sequential minimally invasive procedures appears to be a safe and feasible strategy for the treatment of patients with symptoms from more than one vascular bed. Cathet Cardiovasc Intervent 2001;52:154-161.

Immediate and late clinical outcomes of carotid artery stenting in patients with symptomatic and asymptomatic carotid artery stenosis: a 5-year prospective analysis

BACKGROUND

Carotid stenting is a less invasive percutaneous procedure than carotid endarterectomy for the treatment of carotid stenosis. Reports suggest that it can be performed with periprocedural complication rates similar to those of carotid endarterectomy. The purpose of this study was to determine short- and long-term outcomes in the largest prospective cohort of carotid stenting patients.

METHODS AND RESULTS

This study followed 528 consecutive patients (604 hemispheres/arteries) undergoing carotid stenting. There was a 0.6% (n=3) fatal stroke rate and 1% (n=5) nonstroke death rate at 30 days. The major stroke rate was 1% (n=6), and the minor stroke rate was 4.8% (n=29). The overall 30-day stroke and death rate was 7.4% (n=43). Over the 5-year study period, the 30-day minor stroke rate improved from 7.1% (n=7) for the first year to 3.1% (n=5) for the fifth year (P:<0.05 for trend). The best predictor of 30-day stroke and death was age >/=80 years. After the 30-day period, the incidence of fatal and nonfatal stroke was 3.2% (n=31). On Kaplan-Meier analysis, the 3-year freedom from ipsilateral or fatal stroke was 92+/-1%.

CONCLUSIONS

Experience from a single group of operators demonstrates that carotid stenting can be performed with an acceptable 30-day complication rate. Late follow-up also demonstrates a low rate of fatal and nonfatal stroke. These results suggest that carotid stenting may be comparable to carotid endarterectomy, and it underscores the clinical equipoise and premise for the National Institute of Health-supported, randomized Carotid Revascularization Endarterectomy Versus Stent Trial comparing carotid stenting with carotid endarterectomy.

Validity of duplex ultrasound as a diagnostic modality for internal carotid artery disease

There is an increasing trend to rely on duplex ultrasound rather than angiography to measure an internal carotid artery stenosis. The aim of this study was to determine the validity of ultrasound assessment of carotid stenosis performed in community based vascular laboratories. We compared ultrasound with angiography in 225 patients referred to us for carotid intervention. Mild lesions were diagnosed by ultrasound with a sensitivity of 54%, specificity of 89%, and a positive predictive value of 89% compared with angiography. Severe lesions had a sensitivity of 93%, a specificity of 67%, and a positive predictive value of 45%. Receiver operator characteristic curves demonstrated the optimal ultrasound cut-off value of 66% stenosis as a predictor of >60% stenosis measured angiographically, is associated with a false positive rate of 38%, and a false negative rate of 9%. Similarly, if a cut-off of 76% on ultrasound is used to predict >70% stenosis measured angiographically, it would be associated with a 29% false positive rate and a false negative rate of 11%. Despite the value of non-invasive testing for carotid disease, duplex ultrasonography performed in non-accredited and some accredited laboratories may produce highly variable results. Using ultrasound as the sole diagnostic test to determine the severity of a carotid stenosis may result in a high number of inappropriate operations and a large proportion of patients who may not be offered treatment due to false negative diagnoses.

Carotid stent placement for extracranial carotid artery disease: current state of the art

Percutaneous revascularization techniques have dramatically altered traditional approaches to the management of both coronary and peripheral vascular disease. Their major advantage is that they are less invasive than conventional surgical procedures, offering revascularization without the risk of general anesthesia and with lesser procedural morbidity and mortality, shorter hospital stay, and lower cost. In patients with comorbidities that increase their risk of surgical complications, percutaneous revascularization techniques are the procedures of choice. The Achilles heel of balloon angioplasty, the higher risk of lesion recurrence, restenosis, has been markedly reduced with the use of endovascular stents. Over the past 20 years, percutaneous angioplasty and stenting have become accepted alternatives to surgical revascularization of aortoiliac, renal, femoropopliteal, subclavian, brachiocephalic, and dialysis access lesions. The most recent application of percutaneous intervention has been to explore its clinical utility and safety for stroke prevention in stenotic extracranial carotid arteries. Cathet. Cardiovasc. Intervent. 51:339-346, 2000.