High frequency ultrasound vibrational shear wave elastography for preclinical research.

Preclinical evaluation of novel therapies using models of cancer is an important tool in cancer research, where imaging can provide non-invasive tools to characterise the internal structure and function of tumours. The short propagation paths when imaging tumours and organs in small animals allow the use of high frequencies for both ultrasound and shear waves, providing the opportunity for high-resolution shear wave elastography and hence its use for studying the heterogeneity of tissue elasticity, where heterogeneity may be a predictor of tissue response. Here we demonstrate vibrational shear wave elastography (VSWE) using a mechanical actuator to produce high frequency (up to 1000 Hz) shear waves in preclinical tumours, an alternative to the majority of preclinical ultrasound SWE studies where an acoustic radiation force impulse is required to create a relatively low-frequency broad-band shear-wave pulse. We implement VSWE with a high frequency (17.8 MHz) probe running a focused line-by-line ultrasound imaging sequence which as expected was found to offer improved detection of 1000 Hz shear waves over an ultrafast planar wave imaging sequence in a homogenous tissue-mimicking phantom. We test the VSWE in anex vivotumour xenograft, demonstrating the ability to detect shear waves up to 10 mm from the contactor position at 1000 Hz. By reducing the kernel size used for shear wave speed estimation to 1 mm we are able to produce shear wave speed images with spatial resolution of this order. Finally, we present VSWE data from xenograft tumoursin vivo, demonstrating the feasibility of the technique in mice under isoflurane sedation. Mean shear wave speeds in the tumours are in good agreements with those reported by previous authors. Characterising the frequency dependence of shear wave speed demonstrates the potential to quantify the viscoelastic properties of tumoursin vivo.

A Randomised Phase II Clinical Trial Comparing the Deliverability and Acute Toxicity of Wide Tangent versus Volumetric Modulated Arc Therapy to the Breast and Internal Mammary Chain.

AIMS: Inclusion of the internal mammary chain in the radiotherapy target volume (IMC-RT) improves disease-free and overall survival in higher risk breast cancer patients, but increases radiation doses to heart and lungs. Dosimetric data show that either modified wide-tangential fields (WT) or volumetric modulated arc therapy (VMAT) together with [AQ1]voluntary deep inspiration breath hold (vDIBH) keep mean heart doses below 4 Gy in most patients. However, the impact on departmental resources has not yet been documented. This phase II clinical trial compared the time taken to deliver IMC-RT using either WT and vDIBH or VMAT and vDIBH, together with planning time, dosimetry, set-up reproducibility and toxicity. MATERIALS AND METHODS: Left-sided breast cancer patients requiring IMC-RT were randomised to receive either WT(vDIBH) or VMAT radiotherapy. The primary outcome was treatment time, powered to detect a minimum difference of 75 min (5 min/fraction) between techniques. The population mean displacement, systematic error and random error for cone beam computed tomography chest wall matches in three directions of movement were calculated. Target volume and organ at risk doses were compared between groups. Side-effects, including skin (Radiation Therapy Oncology Group), lung and oesophageal toxicity (Common Terminology Criteria for Adverse Events v 4.03) rates, were compared between the groups over 3 months. Patient-reported outcome measures, including shoulder toxicity at baseline, 6 months and 1 year, were compared. RESULTS: Twenty-one patients were recruited from a single UK centre between February 2017 and January 2018. The mean (standard deviation) total treatment time per fraction for VMAT treatments was 13.2 min (1.7 min) compared with 28.1 min (3.3 min) for WT(vDIBH). There were no statistically significant differences in patient set-up errors in between groups. The average mean heart dose for WT(vDIBH) was 2.6 Gy compared with 3.4 Gy for VMAT(vDIBH) (P = 0.13). The mean ipsilateral lung V17Gy was 32.8% in the WT(vDIBH) group versus 34.4% in the VMAT group (P = 0.2). The humeral head (mean dose 16.8 Gy versus 2.8 Gy), oesophagus (maximum dose 37.3 Gy versus 20.1 Gy) and thyroid (mean dose 22.0 Gy versus 11.2 Gy) all received a statistically significantly higher dose in the VMAT group. There were no statistically significant differences in skin, lung or oesophageal toxicity within 3 months of treatment. Patient-reported outcomes of shoulder toxicity, pain, fatigue, breathlessness and breast symptoms were similar between groups at 1 year. CONCLUSION: VMAT(vDIBH) and WT(vDIBH) are feasible options for locoregional breast radiotherapy including the IMC. VMAT improves nodal coverage and delivers treatment more quickly, resulting in less breath holds for the patient. This is at the cost of increased dose to some non-target tissues. The latter does not appear to translate into increased toxicity in this small study.

The effect of image guidance on dose distributions in breast boost radiotherapy.

AIMS: To determine the effect of image-guided radiotherapy on the dose distributions in breast boost treatments. MATERIALS AND METHODS: Computed tomography images from a cohort of 60 patients treated within the IMPORT HIGH trial (CRUK/06/003) were used to create sequential and concomitant boost treatment plans (30 cases each). Two treatment plans were created for each case using tumour bed planning target volume (PTV) margins of 5 mm (achieved with image-guided radiotherapy) and 8 mm (required for bony anatomy verification). Dose data were collected for breast, lung and heart; differences with margin size were tested for statistical significance. RESULTS: A median decrease of 29 cm(3) (range 11-193 cm(3)) of breast tissue receiving 95% of the prescribed dose was observed where image-guided radiotherapy margins were used. Decreases in doses to lungs, contralateral breast and heart were modest, but statistically significant (P < 0.01). Plan quality was compromised with the 8 mm PTV margin in one in eight sequential boost plans and one third of concomitant boost plans. Tumour bed PTV coverage was <95% (>91%) of the prescribed dose in 12 cases; in addition, the required partial breast median dose was exceeded in nine concomitant boost cases by 0.5-3.7 Gy. CONCLUSIONS: The use of image guidance and, hence, a reduced tumour bed PTV margin, in breast boost radiotherapy resulted in a modest reduction in radiation dose to breast, lung and heart tissues. Reduced margins enabled by image guidance were necessary to discriminate between dose levels to multiple PTVs in the concomitant breast boost plans investigated.

EVAR deployment in anatomically challenging necks outside the IFU.

OBJECTIVE: Treatment of abdominal aortic aneurysms with high-risk anatomy (neck length <10-15 mm, neck angle >60°) using commercially available devices has become increasingly common with expanding institutional experience. We examined whether placement of approved devices in short angled necks provides acceptable durability at early and intermediate time points. METHODS: A total of 218 patients (197 men, 21 women) at a single academic center underwent endovascular aneurysm repair (EVAR) with a commercially available device between January 2004 and December 2007. Available medical records, pre- and postoperative imaging, and clinical follow-up were retrospectively reviewed. Patients were divided into those with suitable anatomy (instructions for use, IFU) for EVAR and those with high-risk anatomic aneurysm characteristics (non-IFU). RESULTS: IFU (n = 143) patients underwent repair with Excluder (40%), AneuRx (34%), and Zenith (26%) devices, whereas non-IFU (n = 75) were preferentially treated with Zenith (57%) over Excluder (25%) and AneuRx (17%). Demographics and medical comorbidities between the groups were similar. Operative mortality was 1.4% (2.1% IFU, 0% non-IFU) with mean follow-up of 35 months (range 12-72). Non-IFU patients tended to have larger sac diameters (46.7% ≥60 mm) with shorter (30.7% ≤10 mm), conical (49.3%), and more angled (68% >60°) necks (all p < .05 compared with IFU patients). Operative characteristics revealed that the non-IFU patients were more likely to be treated utilizing suprarenal fixation devices, to require placement of proximal cuffs (13.3% vs. 2.1%, p = .003), and needed increased fluoroscopy time (31 vs. 25 minutes, p = .02). Contrast dose was similar between groups (IFU = 118 mL, non-IFU = 119 mL, p = .95). There were no early or late surgical conversions. Rates of migration, endoleak, need for reintervention, sac regression, and freedom from aneurysm-related death were similar between the groups (p > .05). CONCLUSIONS: EVAR may be performed safely in high-risk patients with unfavorable neck anatomy using particular commercially available endografts. In our experience, the preferential use of active suprarenal fixation and aggressive use of proximal cuffs is associated with optimal results in these settings. Mid-term outcomes are comparable with those achieved in patients with suitable anatomy using a similar range of EVAR devices. Careful and mandatory long-term follow-up will be necessary to confirm the benefit of treating these high-risk anatomic patients.

Long-term results after accessory renal artery coverage during endovascular aortic aneurysm repair.

OBJECTIVE: Current information regarding coverage of accessory renal arteries (ARAs) during endovascular aneurysm repair (EVAR) is based on small case series with limited follow-up. This study evaluates the outcomes of ARA coverage in a large contemporary cohort. METHODS: Consecutive EVAR data from January 2004 to August 2010 were collected in a prospective database at a University Hospital. Patient and aneurysm-related characteristics, imaging studies, and ARA coverage versus preservation were analyzed. Volumetric analysis of three-dimensional reconstruction computed tomography scans was used to assess renal infarction volume extent. Long-term renal function and overall technical success of aneurysm exclusion were compared. RESULTS: A cohort of 426 EVARs was identified. ARAs were present in 69 patients with a mean follow-up of 27 months (range, 1 to 60 months). Forty-five ARAs were covered in 40 patients; 29 patients had intentional ARA preservation. Patient and anatomic characteristics were similar between groups except that ARA coverage patients had shorter aneurysm necks (P = .03). Renal infarctions occurred in 84% of kidneys with covered ARAs. There was no significant deterioration in long-term glomerular filtration rate when compared with patients in the control group. No difference in the rate of endoleak, secondary procedures, or the requirement for antihypertensive medications was found. CONCLUSIONS: This study is the largest to date with the longest follow-up relating to ARA coverage. Contrary to previous reports, renal infarction after ARA coverage is common. Nevertheless, coverage is well tolerated based upon preservation of renal function without additional morbidity. These results support the long-term safety of ARA coverage for EVAR when necessary.

Evaluation of a three-dimensional ultrasound localisation system incorporating probe pressure correction for use in partial breast irradiation.

This work evaluates a three-dimensional (3D) freehand ultrasound-based localisation system with new probe pressure correction for use in partial breast irradiation. Accuracy and precision of absolute position measurement was measured as a function of imaging depth (ID), object depth, scanning direction and time using a water phantom containing crossed wires. To quantify the improvement in accuracy due to pressure correction, 3D scans of a breast phantom containing ball bearings were obtained with and without pressure. Ball bearing displacements were then measured with and without pressure correction. Using a single scan direction (for all imaging depths), the mean error was <1.3 mm, with the exception of the wires at 68.5 mm imaged with an ID of 85 mm, which gave a mean error of -2.3 mm. Precision was greater than 1 mm for any single scan direction. For multiple scan directions, precision was within 1.7 mm. Probe pressure corrections of between 0 mm and 2.2 mm have been observed for pressure displacements of 1.1 mm to 4.2 mm. Overall, anteroposterior position measurement accuracy increased from 2.2 mm to 1.6 mm and to 1.4 mm for the two opposing scanning directions. Precision is comparable to that reported for other commercially available ultrasound localisation systems, provided that 3D image acquisition is performed in the same scan direction. The existing temporal calibration is imperfect and a "per installation" calibration would further improve the accuracy and precision. Probe pressure correction was shown to improve the accuracy and will be useful for the localisation of the excision cavity in partial breast radiotherapy.

An investigation into the use of CMOS active pixel technology in image-guided radiotherapy.

The increased intelligence, read-out speed, radiation hardness and potential large size of CMOS active pixel sensors (APS) gives them a potential advantage over systems currently used for verification of complex treatments such as IMRT and the tracking of moving tumours. The aim of this work is to investigate the feasibility of using an APS-based system to image the megavoltage treatment beam produced by a linear accelerator (Linac), and to demonstrate the logic which may ultimately be incorporated into future sensor and FPGA design to evaluate treatment and track motion. A CMOS APS was developed by the MI(3) consortium and incorporated into a megavoltage imaging system using the standard lens and mirror configuration employed in camera-based EPIDs. The ability to resolve anatomical structure was evaluated using an Alderson RANDO head phantom, resolution evaluated using a quality control (QC3) phantom and contrast using an in-house developed phantom. A complex intensity-modulated radiotherapy (IMRT) treatment was imaged and two algorithms were used to determine the field-area and delivered dose, and the position of multi-leaf collimator (MLC) leaves off-line. Results were compared with prediction from the prescription and found to agree within a single image frame time for dose delivery and 0.02-0.03 cm for the position of collimator leaves. Such a system therefore shows potential as the basis for an on-line verification system capable of treatment verification and monitoring patient motion.

Impact of endovascular repair on open aortic aneurysm surgical training.

PURPOSE: The purpose of this study was to determine the impact of an endovascular stent-graft program on vascular training in open aortic aneurysm surgery. METHODS: The institutional and vascular surgery fellow experience in aortic aneurysm repair during a 6-year period was reviewed. The 3-year period before introduction of endovascular repair was compared with the 3-year period after introduction of endovascular repair. All patients undergoing abdominal aortic aneurysm (AAA) or thoracoabdominal aortic aneurysm repairs were entered prospectively into a vascular registry and retrospectively analyzed to evaluate the changing patterns in aortic aneurysm treatment and surgical training. RESULTS: Between July 1994 and June 2000, a total of 588 patients with AAA or thoracoabdominal aneurysms were treated at Stanford University Medical Center. There were 296 (50%) open infrarenal AAA repairs, 87 (15%) suprarenal AAA repairs, 47 (8%) thoracoabdominal aneurysm repairs, and 153 (26%) endovascular stent-grafts. The total number of aneurysms repaired per year by vascular fellows before the endovascular program was 71.3 +/- 4.9 (range, 68-77) and increased to 124.7 +/- 35.6 (range, 91-162) after introduction of endovascular repair (P <.05). This increase was primarily caused by the addition of endovascular stent-graft repairs by vascular fellows (51.0 +/- 29.0/year [range, 23-81]). There was no change in the number of open infrarenal aortic aneurysm repairs per year, 53.0 +/- 6.6 (range, 48-56) before endovascular repair versus 47.0 +/- 1.7 (range, 46-49) after (P = not significant). There was a significant increase in the number of suprarenal AAA repairs per year by vascular fellows, 10.0 +/- 1.0 (range, 9-11) before endovascular repair compared with 19.0 +/- 6.5 (range, 13-26) after (P <.05). There was no change in the number of thoracoabdominal aneurysm repairs per year between the two groups, 8.0 +/- 3.0 (range, 4-11) before endovascular repair compared with 7.6 +/- 2.3 (range, 5-9) after. CONCLUSIONS: Introduction of an endovascular aneurysm stent-graft program significantly increased the total number of aneurysms treated. Although the number of open aneurysm repairs has remained the same, the complexity of the open aneurysm experience has increased significantly for vascular fellows in training.

Vascular complications in high-performance athletes.

PURPOSE: The purpose of this study was to evaluate our experience with the diagnosis and management of vascular injuries in a group of high-performance athletes. METHODS: Between June 1994 and June 2000, we treated 26 patients who sustained vascular complications as a result of athletic competition. Clinical presentation, type of athletic competition, location of injury, type of therapy, and degree of rehabilitation were analyzed retrospectively. RESULTS: The mean age of the patients was 23.8 years (range, 17-40). Twenty-one (81%) patients were men, and five (19%) were women. Athletes included 8 major-league baseball players, 7 football players, 2 world-class cyclists, 2 rock climbers, 2 wind surfers, 1 swimmer, 1 kayaker, 1 weight lifter, 1 marksman, and 1 volleyball player. There were 14 (54%) arterial and 12 (46%) venous complications. Arterial injuries included 7 (50%) axillary/subclavian artery or branch artery aneurysms with secondary embolization, 6 (43%) popliteal artery injuries, and 1 (7%) case of intimal hyperplasia and stenosis involving the external iliac artery. Subclavian vein thrombosis (SVT) accounted for all venous complications. Five of the seven patients with axillary/subclavian branch artery aneurysms required lytic therapy for distal emboli, and six required operative intervention. All popliteal artery injuries were treated by femoropopliteal bypass graft with autogenous saphenous vein. The external iliac artery lesion, which occurred in a cyclist, was repaired with limited resection and vein patch angioplasty. All 12 patients with SVT were treated initially with lytic therapy and anticoagulation. Eight patients required thoracic outlet decompression and venolysis of the subclavian vein. Thirteen arterial reconstructions have remained patent at an average follow-up of 31.9 months (range, 2-74). One patient with a popliteal artery injury required reoperation at 2 months for occlusion of his bypass graft. Eleven of the patients with an arterial injury were able to return to their prior level of competition. All of the patients with SVT have remained stable without further venous thrombosis and have returned to their usual level of activity. CONCLUSIONS: Athletes are susceptible to a variety of vascular injuries that may not be easily recognized. A high level of suspicion, a thorough workup including noninvasive studies and arteriography/venography, and prompt treatment are important for a successful outcome.

Will endovascular repair replace open surgery for abdominal aortic aneurysm repair?

OBJECTIVE: To evaluate of the impact of endovascular aneurysm repair on the rate of open surgical repair and on the overall treatment of abdominal aortic aneurysms (AAAs). METHODS: All patients with AAA who were treated during two consecutive 40-month periods were reviewed. During the first period, only open surgical repair was performed; during the subsequent 40 months, endovascular repair and open surgical repair were treatment options. RESULTS: A total of 727 patients with AAA were treated during the entire period. During the initial 40 months, 268 patients were treated with open surgical repair, including 216 infrarenal (81%), 43 complex (16%), and 9 ruptured (3%) aortic aneurysms. During the subsequent 40 months, 459 patients with AAA were treated (71% increase). There was no significant change in the number of patients undergoing open surgical repair and no significant difference in the rate of infrarenal (238 [77%]) and complex (51 [16%]) repairs. A total of 353 patients were referred for endovascular repair. Of these, 190 (54%) were considered candidates for endovascular repair based on computed tomography or arteriographic morphologic criteria. Analyzing a subgroup of 123 patients, the most common primary reasons for ineligibility for endovascular repair were related to morphology of the neck in 80 patients (65%) and of the iliac arteries in 35 patients (28%). A total of 149 patients underwent endovascular repair. Of these, the procedure was successful in 147 (99%), and 2 (1%) patients underwent surgical conversion. The hospital death rate was 0%, and the 30-day death rate was 1%. During a follow-up period of 1 to 39 months (mean 12 +/- 9), 21 secondary procedures to treat endoleak (20) or to maintain graft limb patency (1) were performed in 17 patients (11%). There were no aneurysm ruptures or aneurysm-related deaths. CONCLUSIONS: Endovascular repair appears to have augmented treatment options rather than replaced open surgical repair for patients with AAA. Patients who previously were not candidates for repair because of medical comorbidity may now be safely treated with endovascular repair.

Endovascular repair of abdominal aortic aneurysms: eligibility rate and impact on the rate of open repair.

OBJECTIVE: The purpose of this study was to determine the rate of eligibility among patients with abdominal aortic aneurysms (AAAs) considered for endovascular repair and to examine the effect of an endovascular program on the institutional pattern of AAA repair. METHODS: All patients evaluated for endovascular AAA repair since the inception of an endovascular program were reviewed for determination of eligibility rates and eventual treatment. Open AAA repairs were categorized as simple (uncomplicated infrarenal), complex (juxtarenal, suprarenal, thoracoabdominal, infected), or ruptured, and their rates before and after initiation of an endovascular program were compared. RESULTS: Over 3 years, 324 patients were considered for endovascular AAA repair; 176 (54%) were candidates, 138 (43%) were not candidates, and 10 (3%) did not complete the evaluation. The rate of eligibility increased significantly from 45% (66/148 patients) during the first half of this period to 63% (110/176 patients) during the second half (P <. 001). Candidates were significantly younger (74.4 +/- 7.6 years) than noncandidates (78.3 +/- 6.7 years) (P <.01), and their aneurysm diameter tended to be smaller (57.6 +/- 9.2 mm compared with 60.8 +/- 12.3 mm; P =.06). The most common reason for ineligibility was an inadequate proximal aortic neck. Of 176 candidates, 78% underwent endovascular repair, and 6% underwent open repair. Of 138 noncandidates, 56% underwent surgical repair. Over a period of 6 years, 542 patients with AAAs (429 simple, 86 complex, 27 ruptured) underwent open repair. The total number and ratio of simple to complex open repairs for nonruptured aneurysms during the 3 years before the initiation of the endovascular program (213 simple, 44 complex) were not significantly different from the repairs over the subsequent 3-year period (216 simple, 42 complex). Similarly, no difference in the total number and the ratio of simple to complex open repairs was found between the first and the second 18-month periods since the initiation of the endovascular program. CONCLUSIONS: The rate of eligibility of patients with AAA for endovascular repair appears to be higher than previously reported. The presence of an active endovascular program has not decreased the number or shifted the distribution of open AAA repair.

The oblique talus deformity. What is it, and what is its clinical significance in the scheme of pronatory deformities?

The advantage for maintaining oblique talus deformity as a diagnostic entity is obvious. It describes a deformity that is somewhere between the severe form of flexible pes planus and congenital convex pes valgus. It is important to recognize that the two subsets (oblique talus deformity with maintenance of the calcaneal inclination angle and oblique talus deformity with reversal of the calcaneal inclination) differ from congenital convex pes valgus by the absence of dislocation of the talonavicular joint. In many cases, the talonavicular joint is merely pushed to its maximum range, and does not even meet the definition of subluxation. Maintaining these distinctions prevents overdiagnosis of congenital convex pes valgus. Additionally, better evaluation of treatment for congenital convex pes valgus results because those cases with better prognosis and better response to nonsurgical intervention are not included in the data for the management of congenital convex pes valgus.

Surgical intervention is not required for all patients with subclavian vein thrombosis.

PURPOSE: The role of thoracic outlet decompression in the treatment of primary axillary-subclavian vein thrombosis remains controversial. The timing and indications for surgery are not well defined, and thoracic outlet procedures may be associated with infrequent, but significant, morbidity. We examined the outcomes of patients treated with or without surgery after the results of initial thrombolytic therapy and a short period of outpatient anticoagulation. METHODS: Patients suspected of having a primary deep venous thrombosis underwent an urgent color-flow venous duplex ultrasound scan, followed by a venogram and catheter-directed thrombolysis. They were then converted from heparin to outpatient warfarin. Patients who remained asymptomatic received anticoagulants for 3 months. Patients who, at 4 weeks, had persistent symptoms of venous hypertension and positional obstruction of the subclavian vein, venous collaterals, or both demonstrated by means of venogram underwent thoracic outlet decompression and postoperative anticoagulation for 1 month. RESULTS: Twenty-two patients were treated between June 1996 and June 1999. Of the 18 patients who received catheter-directed thrombolysis, complete patency was achieved in eight patients (44%), and partial patency was achieved in the remaining 10 patients (56%). Nine of 22 patients (41%) did not require surgery, and the remaining 13 patients underwent thoracic outlet decompression through a supraclavicular approach with scalenectomy, first-rib resection, and venolysis. Recurrent thrombosis developed in only one patient during the immediate period of anticoagulation. Eleven of 13 patients (85%) treated with surgery and eight of nine patients (89%) treated without surgery sustained durable relief of their symptoms and a return to their baseline level of physical activity. All patients who underwent surgery maintained their venous patency on follow-up duplex scanning imaging. CONCLUSION: Not all patients with primary axillary-subclavian vein thrombosis require surgical intervention. A period of observation while patients are receiving oral anticoagulation for at least 1 month allows the selection of patients who will do well with nonoperative therapy. Patients with persistent symptoms and venous obstruction should be offered thoracic outlet decompression. Chronic anticoagulation is not required in these patients.

Computed tomographic imaging of the foot and ankle. Developmental and congenital anomalies.

Computed tomography is a primary imaging technique for evaluating congenital and developmental anomalies of the foot and ankle. Other imaging modalities have special capabilities, but computed tomography is a fast, safe, and effective method of assessing the anatomy. To demonstrate this point, the authors present and discuss imaging findings of common anomalies of the foot and ankle.

Open saphenectomy complications following lower extremity revascularization.

A review of saphenectomy site complications following lower extremity revascularization was conducted. Leg incisions used for 133 consecutive infrainguinal bypass procedures were categorized by location. Patient and procedural risk factors were analyzed for risk of wound complications. Procedure, limb and patient outcome were reported via life table analysis. Incisional wound complications followed 32/133 procedures (24%), including 15 groin, eight saphenectomy, five distal and four vein/distal incisions. There were five grade I and three grade II saphenectomy complications. Only weight (body mass index) predicted the likelihood of wound complication (P < 0.05). The 6-month primary patency rate was 79% (mean follow-up 22 months). Four-year assisted primary patency, limb salvage and survival rates were 75, 87 and 57%, respectively. Most bypass-related wound complications (24/32, 75%) involve arterial access incisions. Incisional complications are related to body mass index. Only 6% of GS vein bypass procedures develop saphenectomy site complications. Limiting saphenectomy size may not significantly reduce incisional morbidity following bypass grafting.

Modular systems in the treatment of abdominal aortic aneurysms: lessons learned in the development of designer endografts.

Treatment of abdominal aortic aneurysms with endoluminal stent-grafts is gaining increased interest. Since the original home-made stent-graft was developed in 1991, a multitude of devices have been developed for this treatment. Modular endografts have evolved during this time and offer several significant advantages. Thorough preoperative imaging and assessment is critical to the success of this new therapy for abdominal aortic aneurysms. Lessons learned during the development of the Medtronic AneuRx endograft and its early clinical trials are discussed.

Reoperation for carotid stenosis is as safe as primary carotid endarterectomy.

PURPOSE: Patients with recurrent carotid artery stenosis are sometimes referred for carotid angioplasty and stenting because of reports that carotid reoperation has a higher complication rate than primary carotid endarterectomy. The purpose of this study was to determine whether a difference exists between outcomes of primary carotid endarterectomy and reoperative carotid surgery. METHODS: Medical records were reviewed for all carotid operations performed from September 1993 through March 1998 by vascular surgery faculty at a single academic center. The results of primary carotid endarterectomy and operation for recurrent carotid stenosis were compared. RESULTS: A total of 390 operations were performed on 352 patients. Indications for primary carotid endarterectomy (n = 350) were asymptomatic high-grade stenosis in 42% of the cases, amaurosis fugax and transient ischemic symptoms in 35%, global symptoms in 14%, and previous stroke in 9%. Indications for reoperative carotid surgery (n = 40) were symptomatic recurrent lesions in 50% of the cases and progressive high-grade asymptomatic stenoses in 50%. The results of primary carotid endarterectomy were no postoperative deaths, an overall stroke rate of 1.1% (three postoperative strokes, one preoperative stroke after angiography), and no permanent cranial nerve deficits. The results of operations for recurrent carotid stenosis were no postoperative deaths, no postoperative strokes, and no permanent cranial nerve deficits. In the primary carotid endarterectomy group, the mean hospital length of stay was 2.6 +/- 1. 1 days and the mean hospital cost was $9700. In the reoperative group, the mean length of stay was 2.6 +/- 1.5 days and the mean cost was $13,700. The higher cost of redo surgery is accounted for by a higher preoperative cerebral angiography rate (90%) in redo cases as compared with primary endarterectomy (40%). CONCLUSION: In this series of 390 carotid operations, the procedure-related stroke/death rate was 0.8%. There were no differences between the stroke-death rates after primary carotid endarterectomy and operation for recurrent carotid stenosis. Operation for recurrent carotid stenosis is as safe and effective as primary carotid endarterectomy and should continue to be standard treatment.

Thrombosis with outflow obstruction delays thrombolysis and results in chronic wall thickening of rat veins.

PURPOSE: An in vivo model of acute deep venous thrombosis was developed in rats to assess the role of venous thrombosis and outflow obstruction in recanalization and development of secondary wall changes. METHODS: The left femoral veins of male Sprague-Dawley rats were thrombosed either by means of proximal ligation (obstruction, group A, n = 38) or by means of temporary 24-hour occlusion with a microvascular clamp (unobstructed, group B, n = 20). Right femoral veins served as controls. The rats were killed at intervals over 5 weeks. Wall thickness was compared among groups by means of counting of cells on representative sections through the midvein area. Thrombi were indirectly quantitated with a radiolabeled fibrinogen assay in a parallel series of rats. RESULTS: Control veins showed no evidence of cellular or structural changes. Early thrombus extension was seen in group A (peak at day 4) followed by recanalization after 2 weeks. Group A veins had marked wall thickening (27 +/- 7 vs 6 +/- 2 cells, p < 0.01, peak at 10 days) consisting of smooth muscle-type, neointimal, and medial cellular proliferations. Within 2 to 3 weeks, local neovascular channels had grown to bypass the outflow obstruction, and resumption of normal cephalad flow was seen. At the same time neointimal proliferation regressed, but medial cellular growth persisted, resulting in chronic wall thickening (11 +/- 3 vs 5 +/- 1 cells, p < 0.01, after 21 days). In contrast, group B veins exhibited no thrombus extension, had significantly less wall thickening (13 +/- 2 vs 5 +/- 1 cells, p < 0.01, peak at 4 days), and did not induce growth of local collateral blood vessels. Within 2 weeks, group B veins regained normal appearance and resumed normal flow. CONCLUSIONS: Thrombosis of rat femoral veins without chronic obstruction results in rapid lysis of thrombus and transient proliferative changes. In contrast, thrombosis with chronic outflow obstruction results in delayed recanalization, early extension of thrombus, and development of vigorous and persistent proliferative cellular responses. Thrombus-induced chronic wall thickening may be an important factor in development of postthrombotic venous insufficiency.

Limb salvage surgery in spinal cord injury patients.

Advances in the care and rehabilitation of patients with spinal cord injuries (SCI) have resulted in extended survival following injury. Increasingly, we are faced with difficult chronic lower extremity ischemic complications in SCI patients. Recognizing limitations associated with amputation in these nonambulatory patients, we report the preliminary results of a program of selective limb salvage via arterial reconstructive surgery. Retrospective chart review was performed on the records of the Veterans Affairs Palo Alto Health Care System SCI unit. Since 1989, 15 revascularization procedures were identified in 10 SCI patients. All patients suffered from ischemic ulceration and/or gangrene. Procedures performed included femorotibial bypass (8), aortofemoral bypass (4), femoro-femoral bypass (2), and axillobifemoral bypass (AXF) (1). All patients were men. The mean age was 56 (range 43-73). Follow-up was available on 10 procedures performed in seven patients since 1992. Mean follow-up was 17 months. One patient died 3 months following distal bypass. The AXF occluded within 1 month. One distal bypass occluded in the immediate postoperative period and could not be salvaged. All other grafts remain patent, and all wounds have healed following successful bypass. One patient developed pressure ulceration following AXF grafting due to postoperative upper extremity limitations. No other complications were encountered. Standard arterial reconstructive procedures can be performed safely and successfully in SCI patients, despite diminished limb blood flow due to inactivity, and atrophic arteries, muscle, and fascia. Axillobifemoral bypass grafting may not be suitable in SCI due to requirements for upper extremity-based mobility. Confirmation of benefit of limb salvage versus amputation awaits comparison between patients eligible for either procedure.