Is atherectomy the best first-line therapy for limb salvage in patients with critical limb ischemia?

OBJECTIVE: To determine the efficacy of atherectomy for limb salvage compared with open bypass in patients with critical limb ischemia. METHODS: Ninety-nine consecutive bypass and atherectomy procedures performed for critical limb ischemia between January 2003 and October 2006 were reviewed. RESULTS: A total of 99 cases involving TASC C (n = 43, 44%) and D (n = 56, 56%) lesions were treated with surgical bypass in 59 patients and atherectomy in 33 patients. Bypass and atherectomy achieved similar 1-year primary patency (64% vs 63%; P = .2). However, the 1-year limb salvage rate was greater in the bypass group (87% vs 69%; P = .004). In the tissue loss subgroup, there was a greater limb salvage rate for bypass patients versus atherectomy (79% vs 60%; P = .04). CONCLUSIONS: Patients with critical limb ischemia may do better with open bypass compared with atherectomy as first-line therapy for limb salvage.

Total laparorobotic repair of abdominal aortic aneurysm with sac exclusion obliteration and aortobifemoral bypass.

A 65-year-old man with coronary artery disease, hypertension, and peripheral vascular disease was found to have an asymptomatic abdominal aortic aneurysm (AAA) of 5.5 cm on surveillance for his peripheral vascular disease. Cardiac stress testing demonstrated no evidence of myocardial ischemia, and he opted to undergo open repair of his aneurysm. Laparorobotic repair of the infrarenal AAA using the da Vinci robotic system was performed with an aortobifemoral bypass. We describe a novel technique for AAA exclusion using a cerclage method, which greatly facilitates repair of infrarenal AAAs using laparorobotic techniques. Laparorobotic repair of infrarenal AAA can be greatly facilitated by AAA sac exclusion and obliteration without the need to ligate all lumbar arteries or to open the aneurysm. This virtually avoids blood loss from the sac and minimizes the possibility for open conversion as a result of poor visualization. Minimally invasive aortic intervention for aneurysmal disease using laparascopic methods has been reported in the literature. Problems associated with this technique include a prolonged learning curve and difficulty completing intracorporeal anastomoses. Robotic surgery provides an advantage over laparoscopic surgery in its ability to provide greater degrees of freedom in a relatively small field of view along with superior high-definition, three-dimensional visualization. To date, there have been no known reports of using robotic surgery in the United States as a sole method for repair of AAA. We report our technique of combining robotic surgery with a novel procedure for sac exclusion and obliteration to successfully repair AAA without the need for opening the aneurysm sac and endoaneurysmorrhaphy.

Atherosclerotic plaque progression in carotid arteries: monitoring with high-spatial-resolution MR imaging--multicenter trial.

PURPOSE: To estimate the annualized rate of progression of vessel-wall volume in the carotid arteries in 160 patients by using magnetic resonance (MR) imaging and to establish the fraction of studies that have acceptable image quality. MATERIALS AND METHODS: The study procedures and consent forms were reviewed and approved by each site's institutional review board. All U.S. study sites conducted all phases of this study in compliance with HIPAA requirements. Written consent was obtained from each participant. One hundred sixty patients with greater than 50% narrowing of the diameter of the carotid artery were recruited at six centers for prospective imaging of the carotid arteries at baseline and 1 year later by using high-spatial-resolution, 1.5-T MR imaging. Studies with unacceptable image quality were excluded. Quantitative changes in atheroma volume were measured on unenhanced T1-weighted images. A multiple linear regression analysis was used to correlate progression with several clinical factors, including statin therapy. RESULTS: All 160 patients completed both baseline and follow-up studies. Of these studies, 67.5% were deemed to have image quality that was acceptable for quantitative analysis. The causes of rejection were motion (46%), deep location of the carotid artery (22%), low bifurcation of the carotid artery (13%), and "other" (19%). The mean annual change in vessel-wall volume was 2.31% +/- 10.88 (standard deviation) (P = .014). At 1-year follow-up, vessel-wall volumes in patients not receiving statin therapy had increased faster compared with those in patients receiving statin therapy: 7.87% +/- 13.58% vs 1.14% +/- 9.9%, respectively (P = .029). CONCLUSION: Evaluation of results of a multicenter study indicates that quantitative evaluation of the progression of volume of extracranial carotid vessel walls is feasible with 1.5-T MR imaging despite limitations due to patient motion or habitus. In patients who had preexisting carotid disease, the rate of increase in vessel-wall volume was slower in patients receiving statin therapy.

Local and systemic consequences of large retroperitoneal clot burdens.

BACKGROUND: There is a paucity of data regarding the impact of retroperitoneal hematoma (RPH) volumes, as detected by computed tomography (CT) scanning, on patient morbidity and mortality. Therefore, we wanted to determine the natural history of RPHs and the effect of size on local and systemic outcomes. METHODS: We performed a volumetric analysis of CT-documented RPHs managed at our institution between 1985 and 2006 along with a retrospective chart review. RESULTS: We included 81 cases of RPH in this study. The mean Acute Physiology, Age, and Chronic Health Evaluation II (APACHE II) score was 12.8 +/- 0.72 (score +/- SE). By univariate analysis, the size of the hematoma showed a significant correlation with the development of local mass effects, delayed mass effects, 6-month mortality, major morbidity, pulmonary complications, fluid overload, and the requirement for operative evacuation (p < 0.05). Receiver operating characteristic analysis revealed that a size > or = 1600 cm(3) was > 80% sensitive and specific for predicting a delayed mass effect or an increase in 6-month mortality. Multivariate analysis controlling for factors such as APACHE II and packed red blood cells transfused showed that the volume of the RPH was an independent predictor for the development of local mass effects, pulmonary insufficiency, and fluid overload. CONCLUSIONS: Large RPHs are clearly associated with worse patient outcomes. Surgical intervention may be warranted for the treatment of RPHs > or = 1600 cm(3).

Human carotid plaque calcification and vulnerability. Relationship between degree of plaque calcification, fibrous cap inflammatory gene expression and symptomatology.

BACKGROUND: Inflammation is a key mechanism in human atherosclerotic plaque vulnerability and disruption. The objective was to determine the differential gene expression of pro- and anti-inflammatory factors in the fibrous cap and shoulder region of noncalcified and calcified carotid endarterectomy plaques. METHODS: Thirty carotid endarterectomy plaques were classified as type Va (noncalcified, n = 15) and type Vb (calcified, n = 15) in accordance with the American Heart Association consensus. Using laser capture microdissection, fibrous cap and shoulder regions were excised from frozen sections. Gene expression of pro- [interleukin 1 (IL-1), IL-8 and monocyte chemoattractant protein 1 (MCP-1)] and anti-inflammatory (IL-10) factors, and bone formation (bone morphogenetic protein 6 and osteocalcin) mediators were quantitated by real-time PCR. Protein levels were determined using Western blotting. RESULTS: Mean percent carotid stenosis and calcification area were 79 and 5% in Va-plaques (40% symptomatic) and 77 and 42% in Vb-plaques (20% symptomatic). Macrophages infiltrating the region of the fibrous cap and the shoulder were more numerous in non-calcified plaques compared with calcified plaques (p < 0.01]. mRNA expression of MCP-1 and IL-8, and protein levels of IL-8 were also greater in Va plaques compared to Vb plaques (p < 0.05). Protein levels and mRNA expression of osteocalcin were greater in Vb compared to Va plaques (p < 0.05). CONCLUSIONS: Fibrous cap inflammation is more likely to occur in noncalcified than in calcified plaques. These findings suggest that carotid atherosclerotic plaque calcification is a structural marker of plaque stability.

Direct numerical simulation of transitional flow in a stenosed carotid bifurcation.

The blood flow dynamics of a stenosed, subject-specific, carotid bifurcation were numerically simulated using the spectral element method. Pulsatile inlet conditions were based on in vivo color Doppler ultrasound measurements of blood velocity. The results demonstrated the transitional or weakly turbulent state of the blood flow, which featured rapid velocity and pressure fluctuations in the post-stenotic region of the internal carotid artery (ICA) during systole and laminar flow during diastole. High-frequency vortex shedding was greatest downstream of the stenosis during the deceleration phase of systole. Velocity fluctuations had a frequency within the audible range of 100-300Hz. Instantaneous wall shear stress (WSS) within the stenosis was relatively high during systole ( approximately 25-45Pa) compared to that in a healthy carotid. In addition, high spatial gradients of WSS were present due to flow separation on the inner wall. Oscillatory flow reversal and low pressure were observed distal to the stenosis in the ICA. This study predicts the complex flow field, the turbulence levels and the distribution of the biomechanical stresses present in vivo within a stenosed carotid artery.

Reappraisal of velocity criteria for carotid bulb/internal carotid artery stenosis utilizing high-resolution B-mode ultrasound validated with computed tomography angiography.

OBJECTIVE: Reliability of the most commonly used duplex ultrasound (DUS) velocity thresholds for internal carotid artery (ICA) stenosis has been questioned since these thresholds were developed using less precise methods to grade stenosis severity based on angiography. In this study, maximum percent diameter carotid bulb ICA stenosis (European Carotid Surgery Trial [ECST] method) was objectively measured using high resolution B-mode DUS validated with computed tomography angiography (CTA) and used to determine optimum velocity thresholds for > or =50% and > or =80% bulb internal carotid artery stenosis (ICA). METHODS: B-mode DUS and CTA images of 74 bulb ICA stenoses were compared to validate accuracy of the DUS measurements. In 337 mild, moderate, and severe bulb ICA stenoses (n = 232 patients), the minimal residual lumen and the maximum outer bulb/proximal ICA diameter were determined on longitudinal and transverse images. This in contrast to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) method using normal distal ICA lumen diameter as the denominator. Severe calcified carotid segments and patients with contralateral occlusion were excluded. In each study, the highest peak systolic (PSV) and end-diastolic (EDV) velocities as well as ICA/common carotid artery (CCA) ratio were recorded. Using receiver operating characteristic (ROC) analysis, the optimum threshold for each hemodynamic parameter was determined to predict > or =50% (n = 281) and > or =80% (n = 62) bulb ICA stenosis. RESULTS: Patients mean age was 74 +/- 8 years; 49% females. Clinical risk factors for atherosclerosis included coronary artery disease (40%), diabetes mellitus (32%), hypertension (70%), smoking (34%), and hypercholesterolemia (49%). Thirty-three percent of carotid lesions (n = 110) presented with ischemic cerebrovascular symptoms and 67% (n = 227) were asymptomatic. There was an excellent agreement between B-mode DUS and CTA (r = 0.9, P = .002). The inter/intraobserver agreement (kappa) for B-mode imaging measurements were 0.8 and 0.9, respectively, and for CTA measurements 0.8 and 0.9, respectively. When both PSV of > or =155 cm/s and ICA/CCA ratio of > or =2 were combined for the detection of > or =50% bulb ICA stenosis, a positive predictive value (PPV) of 97% and an accuracy of 82% were obtained. For a > or =80% bulb ICA stenosis, an EDV of > or =140 cm/s, a PSV of > or =370 cm/s and an ICA/CCA ratio of > or =6 had acceptable probability values. CONCLUSION: Compared with established velocity thresholds commonly applied in practice, a substantially higher PSV (155 vs 125 cm/s) was more accurate for detecting > or =50% bulb/ICA stenosis. In combination, a PSV of > or =155 cm/s and an ICA/CCA ratio of > or =2 have excellent predictive value for this stenosis category. For > or =80% bulb ICA stenosis (NASCET 60% stenosis), an EDV of 140 cm/s, a PSV of > or =370 cm/s, and an ICA/CCA ratio of > or =6 are equally reliable and do not indicate any major change from the established criteria. Current DUS > or =50% bulb ICA stenosis criteria appear to overestimate carotid bifurcation disease and may predispose patients with asymptomatic carotid disease to untoward costly diagnostic imaging and intervention.

WITHDRAWN: Reappraisal of internal carotid artery stenosis velocity thresholds utilizing high-resolution B-mode ultrasound validated with computed tomography angiography (CTA).

This article has been withdrawn consistent with Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The Publisher apologizes for any inconvenience this may cause.

Successful percutaneous retrieval of an inferior vena cava filter migrating to the right ventricle in a bariatric patient.

The use of an inferior vena cava filter has an important role in the management of patients who are at high risk for development of pulmonary embolism. Migration is a rare but known complication of inferior vena cava filter placement. We herein describe a case of a prophylactic retrievable vena cava filter migrating to the right ventricle in a bariatric patient. The filter was retrieved percutaneously by transjugular approach and the patient did well postoperatively. A review of the current literature is given.

Transperitoneal versus retroperitoneal suprarenal cross-clamping for repair of abdominal aortic aneurysm with a hostile infrarenal aortic neck.

Infrarenal abdominal aortic aneurysms (AAAs) with a hostile infrarenal aortic neck unfit for endovascular aneurysm repair (EVAR) are more likely to require open repair with suprarenal aortic cross-clamping. We compared the results of the transperitoneal versus retroperitoneal approaches for repair of infrarenal AAA requiring suprarenal cross-clamping and the relative frequency of such techniques after incorporating EVAR into our clinical practice. From January 1998 through September 2005, 478 elective infrarenal aortic aneurysms were repaired. There were 160 (33%) open repairs (71% transperitoneal and 29% retroperitoneal) and 318 (67%) endovascular repairs. In 38 cases (24%) suprarenal cross-clamping was performed (47% transperitoneal and 53% retroperitoneal incisions) for a hostile infrarenal neck. A hostile aortic neck was defined as severe angulation (>60 degrees ), short neck (<15 mm), extensive calcification, or circumferential thrombus. The median age was 70 years; 47% were men; 16% had diabetes mellitus, 29% pulmonary disease, 53% coronary artery disease, and 11% renal insufficiency. The median aneurysm size was 6.0 cm. A retrospective analysis was performed to compare 30-day postoperative outcomes between the trans- and retroperitoneal patient cohorts. The results were determined for two time periods to assess whether open repair with suprarenal cross- clamping was being performed more frequently as a result of increased utilization of EVAR in the contemporary period. After 2002, EVAR increased from 60% to 71% (p = 0.04) while open repair declined from 40% to 29% (p = 0.01). The retroperitoneal approach doubled from 19% to 39%, while the transperitoneal approach decreased from 81% to 61% (p = 0.02). Suprarenal cross-clamping increased by 11% after 2002. There was no significant difference in age, sex, aneurysm size, or comorbidities between the trans- and retroperitoneal groups with suprarenal cross-clamping. The 30-day mortality was 2/38 (5%) and occurred only in the transperitoneal group. The transperitoneal approach was associated with significantly greater blood loss and longer suprarenal cross-clamp times (2,400 vs. 1,800 mL and 38.0 vs. 29.5 min; p = 0.03), but there were no significant differences in 30-day postoperative complications. In our 7 years' experience, there has been a gradual increase in the utilization of EVAR for infrarenal AAAs. At the same time, more infrarenal AAAs with hostile aortic necks requiring suprarenal aortic cross-clamping were encountered. In such instances, the retroperitoneal approach is safer, with less perioperative blood loss and shorter suprarenal cross-clamp time. This is likely attributed to better exposure of the suprarenal abdominal aorta, allowing a more secure proximal anastomosis.

Importance of flow division on transition to turbulence within an arteriovenous graft.

Transitional blood flow in an arteriovenous graft under various conditions of flow division was examined through direct numerical simulation. This junction consists of an inlet vessel (prosthetic graft) connected to a host vessel (vein) at an acute angle (21.6 degrees ). Inlet Reynolds numbers, based on mean velocity and graft inlet diameter, ranged from 800 to 1400. Various flow divisions between the two ends of the host vessel (i.e., the proximal venous segment, PVS, and distal venous segment, DVS) were considered (PVS:DVS ratios of 100:0, 85:15, 70:30 and 115:(15)). The numerical technique employed the spectral element method which is a high-order discretization ideally suited to the simulation of transitional flows in complex domains. High velocity and pressure fluctuations were observed for the PVS:DVS=70:30 and 85:15 cases and absent from the 100:0 and 115:(15) cases; the results indicate the importance of flow division on the development of turbulence in this junction. Transition to turbulence was observed at Reynolds numbers as low as 1000 and 800 under flow divisions of 85:15 and 70:30, respectively, significantly lower than the critical value of 2100. The frequency spectra of velocity fluctuations indicated a significant intensity within the frequency range of approximately 300Hz downstream of the junction. An adverse pressure gradient developed in the PVS when graft inflow divided into opposite directions in the junction. This pressure gradient had a destabilizing effect on the flow and enhanced transition to turbulence in the PVS. These findings suggest that measurements of in vivo flow rates at the inlet and outlets are critical for the accurate prediction of arteriovenous hemodynamics. A potential clinical application of these results might be to close off the DVS during graft construction to ensure a 100:0 flow division.

B-mode ultrasonographic characterization of carotid atherosclerotic plaques in symptomatic and asymptomatic patients.

OBJECTIVE: To identify features on B-mode ultrasonography (US) prevalent in symptomatic plaques and correlate these findings with histopathologic markers of plaque instability. METHODS: Carotid endarterectomy (CEA) plaques from symptomatic and asymptomatic patients with critical stenoses (>70%) were qualitatively assessed using preoperative B-mode US for echolucency and calcific acoustic shadowing. US echolucency was quantitated ex vivo using computerized techniques for gray-scale median (GSM) analysis. Histopathologic correlates for US plaque echolucency (percentage of necrotic core area) and acoustic shadowing (percentage of calcification area) were determined. RESULTS: Fifty CEA plaques were collected from 48 patients (46 unilateral and two bilateral); 26 of these plaques were from symptomatic patients. Age, degree of stenosis, and atherosclerotic risk factors were similar for the symptomatic and asymptomatic patients. Using preoperative B-mode US, 58%, 35%, and 7% of symptomatic plaques and 18%, 41%, and 41% of asymptomatic plaques were found to be echolucent, echogenic, and calcific, respectively (P < .05). Using ex-vivo B-mode US and GSM analysis, symptomatic plaques were more echolucent (41 +/- 19) than asymptomatic plaques (60 +/- 13), P < .03. A strong inverse correlation was found between the percent plaque necrotic area core and GSM (R = -0.9, P < .001). Percentage of calcification area in plaques with acoustic shadowing was 66% and only 27% in those without acoustic shadowing (P < .05). CONCLUSIONS: Using B-mode US, symptomatic plaques are more echolucent and less calcified than asymptomatic plaques and are associated with a greater degree of histopathologic plaque necrosis. Such features are indicative of plaque instability and should be considered in the decision-making algorithm when selecting patients with high-grade asymptomatic carotid stenosis for intervention.

Acoustic radiation from a fluid-filled, subsurface vascular tube with internal turbulent flow due to a constriction.

The vibration of a thin-walled cylindrical, compliant viscoelastic tube with internal turbulent flow due to an axisymmetric constriction is studied theoretically and experimentally. Vibration of the tube is considered with internal fluid coupling only, and with coupling to internal-flowing fluid and external stagnant fluid or external tissue-like viscoelastic material. The theoretical analysis includes the adaptation of a model for turbulence in the internal fluid and its vibratory excitation of and interaction with the tube wall and surrounding viscoelastic medium. Analytical predictions are compared with experimental measurements conducted on a flow model system using laser Doppler vibrometry to measure tube vibration and the vibration of the surrounding viscoelastic medium. Fluid pressure within the tube was measured with miniature hydrophones. Discrepancies between theory and experiment, as well as the coupled nature of the fluid-structure interaction, are described. This study is relevant to and may lead to further insight into the patency and mechanisms of vascular failure, as well as diagnostic techniques utilizing noninvasive acoustic measurements.

Frequency of critical stenosis in primary arteriovenous fistulae before hemodialysis access: should duplex ultrasound surveillance be the standard of care?

OBJECTIVE: Increasing use of primary arteriovenous fistulae (pAVFs) is a desired goal in hemodialysis patients (National Kidney Foundation /Dialysis Outcome Quality Initiative guidelines). However, in many instances, pAVFs fail to adequately mature due to ill-defined mechanisms. We therefore investigated pAVFs with color duplex ultrasound (CDU) surveillance 4 to 12 weeks postoperatively to identify hemodynamically significant abnormalities that may contribute to pAVF failure. METHODS: From March 2001 to October 2003, 54 upper extremity pAVFs were subjected to CDU assessment before access. A peak systolic velocity ratio (SVR) of >/=2:1 was used to detect >/=50% stenosis involving arterial inflow and venous outflow, whereas an SVR of >/=3:1 was used to detect >/=50% anastomotic stenosis. CDU findings were compared with preoperative vein mapping and postoperative fistulography when available. RESULTS: Of 54 pAVFs, there were 23 brachiocephalic, 14 radiocephalic, and 17 basilic vein transpositions. By CDU surveillance, 11 (20%) were occluded and 14 (26%) were negative. Twenty-nine (54%) pAVFs had 38 hemodynamically significant CDU abnormalities. These included 16 (42%) venous outflow, 13 (34%) anastomotic, and 2 (5%) inflow stenoses. In seven (18%), branch steal with reduced flow was found. In 35 of 54 (65%) pAVFs, preoperative vein mapping was available and demonstrated adequate vein size (>/=3 mm) and outflow in 86% of cases. Twenty-one fistulograms (38%) were available for verifying the CDU abnormalities. In each fistulogram, the arterial inflow, anastomosis, and venous outflow were compared with the CDU findings (63 segments). The sensitivity, specificity, and accuracy of CDU in detecting pAVF stenoses >/=50% were 93%, 94%, was 97%, respectively. CONCLUSIONS: Before initiation of hemodialysis, an unexpectedly high prevalence of critical stenoses was found in patent pAVFs using CDU surveillance. These de novo stenoses appear to develop rapidly after arterialization of the upper extremity superficial veins and can be reliably detected by CDU surveillance. Turbulent flow conditions in pAVFs may play a role in inducing progressive vein wall and valve leaflet intimal thickening, although stenoses may be due to venous abnormalities that predate AVF placement. Routine CDU surveillance of pAVFs should be considered to identify and correct flow-limiting stenoses that may compromise pAVF long-term patency and use.

Endovascular solutions to complications of open aortic repair.

Open repair of abdominal aortic aneurysms (AAAs) or occlusive disease can be complicated by pseudoaneurysm formation and aneurysmal dilatation of native vessels. Reports of reoperation for these new lesions have a mortality rate of 5-17% electively, and 24-88% if ruptured. These complications are commonly several years after initial repair, and progression of other comorbidities can further complicate a repeat exploration. The authors reviewed 5 cases of late complications of open aortic bypass surgery treated with endovascular stent grafting as an alternative to reexploration in patients with increased risk for morbidity and mortality. Over a 6-year experience, 5 patients underwent endovascular stent grafting to repair paraanastomotic aneurysms. Patient records were reviewed and clinical cardiac risk evaluation was performed. Follow-up clinic notes and computed tomography (CT) scans were evaluated. Between October 1996 and February 2002, 5 patients underwent 6 endovascular procedures to repair paraanastomotic aneurysms. Mean period between interventions was 16.6 +/-6.27 years (range 10-25); mean age at endovascular procedure 74.2 +/-6.37 years (range 67-84). Cardiac clinical risk index increased in 80% of patients by Goldman Risk Index and in 40% by the Modified Cardiac Risk Index. On completion angiography, there was complete exclusion of the paraanastomotic aneurysms in all cases (100%). Length of postoperative stay was 1.5 +/-0.547 days. Mean estimated blood loss at conclusion of endovascular procedure was 577 +/-546.504 cc (range, 60 cc-1,500 cc). Mean follow-up was 24.4 +/-24.593 months (range, 5-67 months). On repeat imaging, all stent grafts remain patent without rupture or endoleak. Endovascular stent grafting to repair late complications of open AAA repair is a viable alternative to reexploration in patients with significant comorbidities. These procedures can be performed without violating the previous surgical planes of sites. The operations can be performed under local anesthesia and with reduced hospitalizations. In patients with increased risk factors, endovascular stent grafting is a less morbid alternative to open surgical techniques.

Degree of carotid plaque calcification in relation to symptomatic outcome and plaque inflammation.

OBJECTIVE: We undertook this study to quantitate differences in the degree of calcification between symptomatic and asymptomatic plaques removed at carotid endarterectomy (CEA) and to determine associated extent of plaque macrophage infiltration, a histopathologic feature of plaque instability. METHODS: CEA plaques (n = 48) were imaged at 1.25-mm intervals with spiral computed tomography (CT; 10-15 images per plaque). Indications for CEA were transient ischemic attack (n = 16), stroke (n = 5), amaurosis (n = 4), and critical asymptomatic stenosis (n = 23). The percent area calcification for each plaque was determined in spiral CT serial sections and averaged for each plaque. In 31 of 48 plaques macrophage infiltration was quantitated in corresponding histologic sections with immunohistochemical techniques. RESULTS: The mean (+/- SD) age of patients with symptomatic and asymptomatic plaques was 66 +/- 7 years vs 71 +/- 7 years, respectively, and degree of stenosis was 76% versus 82%, respectively (P =.05). Atherosclerosis risk factors were similar between groups. Percent plaque area calcification was twofold greater in asymptomatic versus symptomatic plaques (48% +/- 19% vs 24% +/- 20%, respectively; P <.05). At receiver operating characteristic curve analysis, 80% of symptomatic plaques were below and 87% of asymptomatic plaques were above a cutoff point of 30% plaque area calcification. Macrophage burden was greater in the symptomatic plaques than in the asymptomatic plaques (52% vs 23%; P <.03). A strong inverse relationship between the degree of plaque calcification and macrophage infiltration was found in critical carotid stenoses (r = -0.87; P <.001). CONCLUSIONS: Symptomatic plaques are less calcified and more inflamed than asymptomatic plaques. Regardless of clinical outcome, a strong inverse correlation was found between the extent of carotid plaque calcification and the intensity of plaque fibrous cap inflammation as determined by the degree of macrophage infiltration. Carotid plaque calcification is associated with plaque stability, and is a potential spiral CT in vivo quantitative marker for cerebrovascular ischemic event risk.

Limb salvage after infrainguinal bypass graft failure.

OBJECTIVE: The purpose of this study was to examine the outcome of patients in whom an infrainguinal bypass graft failed. METHODS: This was a retrospective analysis of consecutive patients undergoing infrainguinal bypass grafting in a single institution over 8 years. RESULTS: Six hundred thirty-one infrainguinal bypass grafts were placed in 578 limbs in 503 patients during the study period. The indication for surgery was limb-threatening ischemia in 533 patients (85%); nonautologous conduits were used in 259 patients (41%), and 144 (23%) were repeat operations. After a mean follow-up of 28 +/- 1 months (median, 23 months; range, 0-99 months), 167 grafts (26%) had failed secondarily. The rate of limb salvage in patients with graft failure was poor, only 50% +/- 5% at 2 years after failure. The 2-year limb salvage rate depended on the initial indication for bypass grafting: 100% in patients with claudication (n = 16), 55% +/- 8% in patients with rest pain (n = 49), and 34% +/- 6% in patients with tissue loss (n = 73; P <.001). The prospect for limb salvage also depended on the duration that the graft remained patent. Early graft failure (<30 days; n = 25) carried a poor prognosis, with 2-year limb salvage of only 25% +/- 10%; limb salvage was 53% +/- 5% after intermediate graft failure (<2 years, n = 110) and 79% +/- 10% after late failure (>2 years, n = 15; P =.04). Multivariate analysis revealed shorter patency interval before failure (P =.006), use of warfarin sodium (Coumadin) postoperatively (P =.006), and infrapopliteal distal anastomosis (P =.01) as significant predictors for ultimate limb loss. CONCLUSION: The overall prognosis for limb salvage in patients with failed infrainguinal bypass grafts is poor, particularly in patients with grafts placed because of tissue loss and those with early graft failure.

Redo infrainguinal bypass: factors predicting patency and limb salvage.

The increased complexity of redo infrainguinal bypass procedures can result in prolonged operative time and increased morbidity. This review was undertaken to compare outcomes from primary and redo bypass procedures and to identify factors predictive of graft failure and limb loss after redo bypass. All infrainguinal bypasses ( n = 468) from 1995 to 1999 were reviewed. A total of 367 primary bypasses in 317 patients were compared to 101 redo grafts in 84 patients with previously failed bypasses. Risk factors and types of procedures were compared using Student's t-test and the chi(2) test. Patency and limb salvage were compared using life-table analysis. Patients requiring redo bypasses were less likely to have diabetes and end-stage renal disease. Two-year patency (66 +/- 4% primary vs. 55 +/- 7% redo, p = 0.13) and limb salvage (75 +/- 3% primary vs. 72 +/- 6% secondary, p = 0.43) were comparable between primary and redo bypass groups. Female gender was predictive of redo graft failure (2-year patency 73 +/- 8% male vs. 39 +/- 9% female, p = 0.01). Clinical indications that predicted failure of a redo bypass included thrombosis of an autologous graft (1-year patency 71 +/- 7% previous prosthetic vs. 49 +/- 10% previous autologous, p = 0.004), thrombosis of an infrageniculate bypass (2-year patency 65 +/- 10% suprageniculate vs. 46 +/- 9% infrageniculate, p = 0.044), and a limb salvage indication for the primary operation (2-year patency 86 +/- 9% claudication vs. 44 +/- 8% limb salvage, p = 0.008). When a primary bypass fails despite the use of optimal conduit (autologous vein) and an infrageniculate target vessel, the redo bypass has a higher risk of failure, particularly in female patients. Nonetheless, patency and limb salvage rates justify an attempt at revascularization after failed primary bypass.

Reliability of common femoral artery hemodynamics in assessing the severity of aortoiliac inflow disease.

OBJECTIVES: We investigated the utility of color duplex ultrasound (CDU)-derived common femoral artery (CFA) hemodynamics for detecting significant aortoiliac occlusive disease and predicting its severity. METHODS: From January 1997 to June 2001, 132 consecutive patients with lower extremity arterial insufficiency underwent both femoropopliteal CDU scanning and aortography with runoff studies. CDU-derived CFA waveform contour (monophasic, biphasic, or triphasic), peak systolic velocity (PSV), and acceleration time were recorded for each patient. Severity of aortoiliac occlusive disease was classified by arteriography into three distinct groups: normal or minimal disease (<50%, group 1), significant focal or diffuse stenoses (>/=50%, group 2), or total occlusion (group 3). Using probability and receiver operating characteristic curve analysis, waveform contour and PSV were compared alone and in combination with the arteriographic groups to identify waveform contours and threshold PSV, which may accurately differentiate the three categories of aortoiliac occlusive disease. RESULTS: Of 214 limbs available for study, 112 composed group 1, 70 composed group 2, and 32 composed group 3. Concomitant femoropopliteal disease was present in 47% of limbs in group 1, 53% of limbs in group 2, and 34% of limbs in group III. An abnormal CFA waveform contour (monophasic or biphasic) differentiated group 1 from groups 2 and 3, with 95% sensitivity, 89% specificity, 89% positive predictive value (PPV), 95% negative predictive value (NPV), and 92% accuracy. Mean PSV and acceleration time for monophasic and biphasic waveforms were 39 cm/sec +/- 19, 178 msec +/- 36 vs 95 cm/sec +/- 67, 97 msec +/- 31 respectively (P <.05). In differentiating between groups 2 and 3, the specificity, PPV, and accuracy for CFA PSV of