Does repeat duplex ultrasound for lower extremity deep vein thrombosis influence patient management?

The clinical significance of lower extremity deep vein thrombus (DVT) propagation in the setting of anticoagulation therapy remains unclear. The purpose of this study is to compare results of thrombus outcome found with repeat duplex ultrasonography to the incidence of pulmonary embolism and mortality. During a recent 18-month period, 457 patients were diagnosed with lower extremity DVT with duplex ultrasonography and their data were retrospectively analyzed. Repeat examinations were available for review in 118 patients (51 men, 67 women). Results of repeat duplex exams were divided into 4 groups: resolved, improved, unchanged, or extended proximally. All patients received heparin and warfarin therapy. Ventilation-perfusion (V/ Q) scans were obtained only for signs and symptoms of pulmonary embolism (n=30). Mortality, the prevalence of high-probability V/ Q scans, frequency of intracaval filter insertion, gender, mean age, mean prothrombin time (PT), mean partial thromboplastin time (PTT), mean number of repeat ultrasounds per patient, and mean time over which the repeat ultrasounds took place were compared among the 4 groups. Patients who had proximal extension of DVT (19%) on repeat duplex ultrasound had an increased prevalence of pulmonary embolism (p<0.05). Also, patients whose DVT resolved were younger (p<0.05). There was no difference among the 4 groups in mortality, placement of Greenfield filters, mean PT, mean PTT, mean number of ultrasound exams per patient, or mean follow-up time over which the exams took place. Proximal extension of DVT documented by repeat duplex ultrasound is a significant risk factor for pulmonary embolism. Repeat duplex ultrasound can identify a group of patients who may benefit from insertion of an intracaval filter device.

The role of the endovascular surgeon for lower extremity ischemia.

UNLABELLED: Since the data investigating endovascular therapy performed by surgeons is scarce, we retrospectively reviewed our experience of endovascular procedures performed by vascular surgeons in the operating room for lower extremity ischemia due to stenotic lesions. METHODS: A total of 14,424 procedures were performed by our division between January 1990--October 2003. Of these, 500 involved a balloon angioplasty. These made up 3.5% of the total caseload. The median age of the patients who underwent these 500 balloon angioplasty was 72+/-0.5 years old; 65% were male; 50% had a history of diabetes mellitus, and 6% had ESRD. Indications for the procedures included acute ischemia (47 cases), critical ischemia (rest pain, gangrene, or ischemic ulcers in 254 cases), failing bypass (64 cases), severe claudication (134 cases), and preoperative for a popliteal artery aneurysm repair. RESULTS: 244 of the procedures were percutaneous, and the remaining 256 were combined with some type of open procedure. Those performed as an open technique were in combination with a bypass (135 cases) and in combination with a patch angioplasty (31cases). Balloon angioplasties were performed of the aorta (5 cases), iliac arteries (281 cases), the superficial femoral artery (SFA) (101 cases), the popliteal artery (44 cases), the tibial vessels (77 cases), the subclavian/axillary artery (5 cases) and failing grafts (26 cases). Balloon angioplasty was attempted in eight cases and failed due to inability to cross the lesion with a guidewire. Intraoperative complications included 4 dissections, inability to dilate the lesion adequately (2 cases), and rupture of two iliac lesions that underwent open repair (1 case) or repair with a stent graft (1 case). Stents were initially used highly selectively but recently are now being deployed more liberally in the iliac arteries (total 251 cases with stents). CONCLUSIONS: Based on these data, we suggest that balloon angioplasty is a useful tool that can be performed by vascular surgeons safely. The advantages to the patients include one combined procedure to treat lower extremity ischemia.

Carotid endarterectomy in octogenarians and nonagenarians : is it worth the effort?

PURPOSE: The safety, effectiveness and cost issues of carotid endarterectomy (CEA) in the elderly patient have been debated due to the limited life expectancy and presumably increased rate of complications. This is despite multiple reports in the literature of excellent results in this population. To further examine this issue, we compared characteristics of three populations who underwent CEA at our institution: 53-79 year old patients (youngest group), 80-89 years old patients (middle group), and 90-98 year old patients (oldest group). METHODS: Medical and financial data were obtained by retrospective review of hospital charts and billing records. We analyzed 266 random CEAs performed in 251 patients in the youngest group, 280 CEAs performed in 247 patients in the middle group and 19 CEA in 16 patients in the oldest group performed between 2/1/90 and 2/5/01. RESULTS: Comparing each CEA group, there were no differences in gender (males: 56% vs. 51% vs. 53%), incidence of preoperative symptoms (43% vs. 43% vs. 42%), hypertension (68% vs. 60% vs. 42%), combined perioperative death and stroke rate (1.8% vs. 2.1% vs. 10%) or other complications (11% vs. 10% vs. 10%). Significant differences (p<0.05) were noted between the groups in incidence of diabetes (33% vs. 51% vs. 5% in each group), and heart disease (28% vs. 38% vs. 21%). Length of stay for admissions for CEA only were also similar in all three groups (2.37 days vs. 2.67 days vs. 2.36 days). A cost analysis of the earliest 230 patients in the entire series examining hospital cost per case revealed similar data for the < 80 years old and > 80 year old patients ($7,842 vs. $9,400). CONCLUSIONS: Carotid endarterectomy can be performed in the elderly as safely and cost effectively as in the younger population.

Carotid surgery without external carotid endarterectomy: a 6-year clinical experience with 1027 cases.

PURPOSE: previously we routinely performed endarterectomy of the external carotid artery (ECA) during carotid surgery. However, discouraging experience and lack of supportive data in the literature made us question its necessity. The present report describes our experience with a modified carotid endarterectomy (CEA) technique where the ECA is left undisturbed regardless of its degree of stenosis. METHODS: from January 1996 to June 2001, 1027 CEAs were performed in 905 patients with this technique at our institution. All operations were performed for at least 60% internal carotid artery (ICA) stenosis. A preoperative carotid duplex scan was available for review in 990 cases (96%). Follow-up duplex scans were recovered from 0 to 1 months in 851 cases (83%) and from >1 month in 655 cases (64%). Seventy percent of these cases were performed for asymptomatic lesions. RESULTS: the perioperative (30-day) mortality rate for the entire group of patients was 0.5% and the stroke rate was 0.7%. Mean follow-up was 18 months (range: 2-66 months). Only two ECAs occluded in the first postoperative month. During the follow-up period, 37 additional ECAs (5.6%) were found to progress from mild to severe (>75%) stenosis postoperatively. In addition, 7% of the cases were found to have worsened the degree of stenosis, 8% improved and 85% remained unchanged. CONCLUSION: these data support sparing of the ECA during CEA.

Comparison of Magnetic Resonance Angiography (MRA) and Duplex Ultrasound Arterial Mapping (DUAM) prior to infrainguinal arterial reconstruction.

OBJECTIVE: the purpose of this study is to compare Magnetic Resonance Angiography (MRA) to Duplex Ultrasound Arterial Mapping (DUAM) and intraoperative findings to determine the clinical, accuracy of MRA for planning lower extremity revascularization procedures. METHODS: forty-two patients who underwent lower extremity revascularization procedures had both MRA and DUAM evaluations. These data were analyzed retrospectively and two distinct endpoints were considered. First, we compared the MRA and DUAM findings for aorto-iliac, femoral-popliteal and infra-popliteal segments to intraoperative findings and evaluated the degree to which they agreed. Second, if there was a disagreement between imaging modalities, it was established whether a change in operative procedure would have resulted. RESULTS: MRA and DUAM findings agreed in 26 of 31 cases (83%) of aorto-iliac segments, in 25 of 31 cases (81%) of femoral-popliteal segments, and in 16 of 21 cases (76%) of infra-popliteal segments. In total, DUAM agreed with intraoperative findings in 98% of cases while MRA agreed in 82% (p<.001). Disagreement between intraoperative findings and DUAM lead to an alternate surgical procedure in only one case (2%) while disagreement with MRA lead to a different procedure in 38% of cases (p<.001). CONCLUSIONS: these data show that MRA is not yet adequate to replace conventional angiography and is less accurate that DUAM. Further improvements are necessary before MRA can be used as the sole modality for formulation of a pre-operative plan for lower extremity revascularization.

Combined upper and lower extremity deep venous thrombosis.

In order to elucidate the natural history of upper extremity deep venous thrombosis (UEDVT), we compared the morbidity and mortality of patients with UEDVT and that of patients with both UEDVT and lower extremity deep venous thrombosis (LEDVT). Between 1993 and 1996, 21 patients presented to our institution with both LEDVT and UEDVT (Group 1). During the same time period, 144 patients were diagnosed with UEDVT alone (Group 2). The diagnosis was confirmed by duplex scanning in all patients. In Group 1, there were 14 females (67%) and 7 males (23%) with ages ranging from 25 to 97 yr old [mean 73 yr old +/-17 yr (SD)]. In Group 2, there were 84 females (58%) and 60 males (42%) with ages ranging from 9 to 101 yr old [mean 67 yr old +/-17 yr (SD)]. Differences in age and sex between the two groups were not statistically significant. In Group 1, systemic anticoagulation was implemented in 17 patients (81%). Two patients (9.5%) required placement of a SVC and IVC filters due to contraindication to anticoagulation. One patient did not receive anticoagulation, and one patient was only started on aspirin. In Group 2, treatment consisted of systemic anticoagulation in 94 patients (65%). The remainder of the patients were treated with aspirin in three patients (2%) or no anticoagulation in 31 patients (19%). Sixteen patients (11%) underwent placement of a SVC filter either due to failure of anticoagulation to prevent pulmonary embolism (two patients) or contraindication to anticoagulation (14 patients). Pulmonary emboli were documented by ventilation/perfusion lung scan in two patients (9.5%) in Group 1 and in 16 patients (11%) in Group 2. In the first group, 8 of the 21 patients (38%) were dead within 1 month of the diagnosis of UEDVT, and 11 of 21 patients (52%) were dead within 2 months of the diagnosis of UEDVT. In the second group, 20 of 144 patients (14%) were dead within 1 month of the diagnosis of UEDVT and 38 of 144 patients (26%) were dead within 2 months of diagnosis (P<0.02). Our data suggest that patients with both UEDVT and LEDVT have a higher mortality than patients with UEDVT alone. As the risk for pulmonary embolism is similar in both groups, we speculate that the severity of medical illness in patients with both UEDVT and LEDVT may contribute to the higher mortality. This is the first study to examine the mortality of this group of patients.

Von Hippel-Lindau gene therapy: a novel strategy in limiting endothelial cell proliferative activity.

There is evidence that loss of function of the von Hippel-Lindau (VHL) gene causes transcriptional activation of the vascular endothelial growth factor (VEGF) gene, which in turn may lead to increased proliferation of vascular endothelial cells. We hypothesized that transfer of VHL gene, a tumor suppressor gene, into vascular endothelial cells could cause loss of viability and suppression of its proliferative ability. Human aortic endothelial cells (HAEC) were grown as monolayers and transfected with varying titers of adenovirus containing the VHL cDNA (AdVHL). The negative controls used were adenovirus containing green fluorescent protein (AdGFP), vector alone (AdNull), and infection medium without virus. Adenovirus encoding p53 (Adp53) was used as positive control. Cell viability and proliferation were determined by trypan blue dye exclusion and by a tetrazolium-based colorimetric assay. All experiments were performed in triplicate. Our results showed that proliferative activity in HAEC can be blocked and viability of HAEC reduced by adenovirus-mediated gene transfer of VHL gene. This is the first time that VHL gene has been effectively transferred to HAEC. VHL gene transfer into the vascular endothelium may have potential in limiting proliferative processes, including intimal hyperplasia.

Posterior transverse plication technique for treatment of redundant internal carotid artery during endarterectomy.

PURPOSE: Posterior transverse plication (PTP) has gained popularity as a technique to correct redundancy of the internal carotid artery during endarterectomy. The safety of this technique in large series of patients has not been extensively studied. We investigated 876 primary carotid endarterectomies (CEAs) performed at our institution over the last six years to determine the safety of this technique. METHODS: Indication for surgery was carotid stenosis >/=70% in 341 (39%) symptomatic and 535 (61%) asymptomatic cases. Preoperative imaging consisted of duplex ultrasound alone or combined with magnetic resonance angiography. Patients were divided into four groups related to surgical technique: CEA+PTP+8mm patch (group Ia), CEA+PTP+10mm patch (group Ib), CEA+patch (group II) and CEA+primary closure (group III). There were 43, 39, 581 and 213 patients in groups Ia, Ib, II and III, respectively. No statistical differences in age, sex or risk factors for atherosclerotic disease were noted among the groups. Postoperative duplex ultrasonography was used at 2weeks and every 6months thereafter to evaluate the adequacy of the repair and presence of complications such as pseudoaneurysm formation and extrinsic compression by the excluded carotid segment. RESULTS: The 30-day mortality was 1.2%, 0.6% and 0.3% for groups I, II and III, respectively. Stroke rates for the same period were 0%, 0.6% and 0.8% for groups I, II and III, respectively. Duplex ultrasonography demonstrated significant stenosis (>/=50%) in two (5%) patients in group Ia at 12months. No restenosis was observed in group Ib. For groups II and III the rates of restenosis were 1.5% and 0.8%. One patient in group II developed a pseudoaneurysm after 7months. CONCLUSION: Posterior transverse plication safely corrects redundancy of the internal carotid artery during endarterectomy without causing early significant restenosis. Continued follow-up in a larger group of patients to determine long-term efficacy and correlation between patch size and restenosis rate is warranted.

Routine preoperative carotid duplex scanning in patients undergoing open heart surgery: is it worthwhile?

It has been reported that carotid screening may be cost-effective in patient populations in which the prevalence of severe carotid stenosis exceeds 4.5%. In order to identify potential patient populations who might benefit from carotid screening, we examined the results of preoperative duplex scanning in patients undergoing open heart surgery. Between January 1995 and July 1998, 3708 patients (59% male, 41% female) underwent open heart surgery at our institution. Of these, 3081 underwent coronary artery bypass grafting (CABG), 364 underwent valve replacement (VR), and 263 underwent CABG and VR. The ages of these patients ranged from 40 years to 98 years (mean 68 +/- 11 years). The risk factors analyzed included hypertension (HTN), 59%; smoking (Smk), 53%; and diabetes (DM), 33%. Patients were divided into three groups according to their age. Group A consisted of the 835 patients who were < or = 60 years old, group B consisted of 2474 patients ranging from 61 years to 80 years old, and group C consisted of 399 patients who were > or = 81 years old. All patients underwent bilateral preoperative carotid duplex scans at an Intersocietal Commission for the Accreditation of Vascular Laboratories (ICAVL)-accredited vascular laboratory. Statistical analyses were performed using chi-squared, Fisher's exact test, linear regression, and multivariate analysis. From our results we concluded that carotid screening is not recommended for patients under 60 years of age who are undergoing CABG unless they present with a minimum of two of the following major risk factors: hypertension, diabetes, or smoking. However, carotid screening is recommended for all patients undergoing open heart operations who are over the age of 60 years old, regardless of the absence of associated risk factors.

Lessons learned from a 6-year clinical experience with superior vena cava Greenfield filters.

PURPOSE: Therapy to prevent pulmonary embolism (PE) resulting from upper extremity deep venous thrombosis (UEDVT) remains controversial despite an increasing incidence of DVT of upper extremity origin. The purpose of this study was to evaluate the results of 72 superior vena cava Greenfield filters (SVC-GFs) placed in patients at risk for PE arising from UEDVT. METHODS: During the past 78 months, we placed SVC-GFs in 72 patients with UEDVT in whom anticoagulation was either deemed contraindicated (n = 67) or proved ineffective in preventing recurrent PE (n = 4) or extension of the thrombus (n = 1). There were 25 male (35%) and 47 (65%) female patients whose ages ranged from 25 to 99 years (mean, 74 years). Follow-up ranged from 10 days to 78 months (mean, 7.8 months). Sequential chest radiographs revealed no filter migration or displacement in 26 patients. RESULTS: Thirty-four patients died in the hospital of causes unrelated to the SVC filter or recurrent thromboembolism (mean time to death, 20 days). Follow-up of the surviving 38 patients ranged from 1 month to 78 months (mean, 22 months); none of these patients were seen with any evidence of PE. One SVC-GF was incorrectly discharged into the innominate vein and left in place. This vein remains patent 2 months after insertion without evidence of filter migration. CONCLUSIONS: We think that insertion of SVC-GFs is a safe, efficacious, and feasible therapy and may prevent recurrent thromboembolism in patients with UEDVT who are resistant to anticoagulation or have contraindications to anticoagulation.

Upper extremity deep venous thrombosis: an underrecognized manifestation of a hypercoagulable state.

Although lower extremity deep venous thrombosis (LEDVT) has been associated with a hypercoagulable state, there are scant data available for patients presenting with upper extremity deep venous thrombosis (UEDVT). Therefore, we conducted a prospective study to determine whether such an association exists for UEDVT. Fifty-two patients who presented with UEDVT at our institution from August 1996 to June 1997 underwent a hematological profile consisting of activated protein C (APC) resistance, antithrombin III (ATIII) level and activity, factor V mutation (arginine 506 to glycine), protein C level and activity, protein S level and activity, factors II and X activity, lupus anticoagulant, and cardiolipin antibody. This represented 68% (52/76) of the total number of patients in whom the diagnosis of UEDVT was made by duplex ultrasonography during this time period. The ages ranged from 9 to 97 (mean 63 +/- 23 years). There were 22 males and 30 females. Twenty-five patients (48%) had a central venous line in place, 4 patients (8%) had a pacemaker, 14 patients (27%) had a history of neoplasm, and 7 patients (13%) had concomitant LEDVT. The results of our study showed that a hypercoagulable state may be an underappreciated contributing factor in the development of UEDVT. Contrary to prior belief that three sets of tests are needed to confirm the presence of a hypercoagulable state, these data also suggest that only two tests may be needed.

Lower-extremity revascularisation without preoperative contrast arteriography in 185 cases: lessons learned with duplex ultrasound arterial mapping.

PURPOSE: we have previously reported our experience with lower-extremity duplex-ultrasound arterial mapping (DUAM) compared to contrast arteriography (CA) to predict lower-extremity bypass sites. The present study evaluates arterial revascularisation procedures for chronic limb ischaemia based on DUAM. MATERIALS AND METHODS: from January 1998 to July 1999, 195 patients (128 men, 67 women) underwent 211 lower-extremity revascularisation procedures based on DUAM. Indications for surgery were tissue loss, severe claudication, rest pain and popliteal aneurysm in 57%, 25%, 14% and 4% of the limbs, respectively. The mean age was 72+/-12 years and risk factors such as diabetes, hypertension, tobacco use, coronary artery and end-stage renal disease were present in 53%, 58%, 53%, 50% and 12% of the patients, respectively. Previous revascularisation procedures had been performed in 23% of the limbs. Preoperative evaluation consisted of DUAM alone (185) or of a combination of DUAM and CA (29 limbs). CA was deemed necessary due to a combination of technical difficulties that jeopardized adequate sonographic imaging and presence of disadvantaged run-off for medico-legal reasons. DUAM consisted of direct imaging of all major arteries from the distal aorta to the pedal circulation. Optimal inflow and outflow bypass anastomotic sites were selected according to a diagram based on DUAM. Adequacy of the inflow was additionally assessed by common-femoral-artery waveform and confirmed by intraoperative pressure measurements. Post-bypass CA was obtained to verify patency of the run-off. RESULTS: DUAM procedure time averaged 75+/-26 min. For patients who underwent only DUAM, the distal anastomosis was to the popliteal artery in 91 cases and to tibial or pedal arteries in 58 cases. Distal anastomosis was proximal to a significant lesion in two cases that required jump grafts. Cumulative patency rates at 1 and 3 months for popliteal bypasses were 96% and 90%, and for infrapopliteal bypasses 90% and 83%, respectively. Inflow procedures to the femoral artery, patch and balloon angioplasties accounted for the remaining 40 cases. Four primary amputations were performed after CA confirmed DUAM findings. CONCLUSIONS: contrary to general belief, these data show that high-quality arterial ultrasonography represents a safe alternative to preoperative CA, even for infrapopliteal bypasses. This non-invasive approach may be especially useful for patients with contrast allergy or impaired renal function.

Changes in the practice of angioaccess surgery: impact of dialysis outcome and quality initiative recommendations.

PURPOSE: Recommendations recently published by the National Kidney Foundation-Dialysis Outcome and Quality Initiative (DOQI) included an appeal for increased use of native arteriovenous fistulas (NAVFs) to improve overall patency and contain angioaccess costs. We evaluated the impact of the DOQI recommendations on angioaccess surgery and its outcome at our institution. METHODS: From June 1996 to April 1999, 483 angioaccess procedures were performed on 247 patients. There were 133 men and 114 women, with an average age ranging from 28 to 95 years (mean age, 69 +/- 0.59 years). Risk factors included smoking in 143 patients (58%), diabetes mellitus in 135 patients (55%), hypertension in 150 patients (61%), and coronary artery disease in 98 patients (40%). The patients were divided in two groups. Group I (pre-DOQI) included patients who had angioaccess procedures between June 1996 and November 1997, and group II (post-DOQI) included patients who had angioaccess procedures between December 1997 and April 1999. The types of procedures performed included placement of arteriovenous grafts (AVGs) in 122 patients (25%), creation of NAVFs in 99 patients (20%), revision of AVGs in 123 patients (25%), and temporary access procedures in 135 patients (28%). Forty-seven of the NAVF procedures were radial-cephalic fistulas (47%), 22 were brachial-cephalic fistulas (23%), and 30 were brachial-basilic fistulas (30%). Patients underwent serial ultrasonography scanning and physical examinations; the mean follow-up period was 9 months. Choice of angioaccess procedures and patency rates before and after implementation of the DOQI recommendations were compared. RESULTS: There was a significant increase in the use of NAVFs after implementing DOQI recommendations (5% vs 68%, P <.001). The 1-year primary patency rate of AVGs was less than that of arteriovenous fistulas (54% vs 85%, P <.001). During the study period, the percentage of AVGs placed at our institution that required revision (59%; 72 of 123) was higher than that of NAVFs that required revision (4%; 4 of 99; P <.001). There was no significant difference in the maturation rates of radial-cephalic fistulas (75%), brachial-cephalic fistulas (91%), and brachial-basilic fistulas (87%). CONCLUSION: By adopting the DOQI recommendations, we used NAVFs more often. This resulted in superior patency rates, compared with synthetic grafts. The liberal use of preoperative duplex venous mapping further increased NAVF use, surpassing the DOQI expectations for primary arteriovenous fistulas. Additionally, fewer revisions were required.

Ruptured versus elective abdominal aortic aneurysm repair: outcome and cost.

During a recent 30-month period, we repaired 10 ruptured abdominal aortic aneurysms (RAAA) at our institution. To evaluate the survival, postoperative morbidity, and financial impact of treating RAAA, we compared these patients with 10 randomly selected patients undergoing elective AAA (EAAA). Both groups were comparable for age, gender, and incidence of diabetes, hypertension, coronary artery disease, chronic obstructive pulmonary disease (COPD), and renal failure. Although we have noted a dramatic increase in survival for RAAA (90%), the morbidity continues to be unacceptably high (60%). Efforts should be made toward better detection of AAA prior to rupture as well as development of strategies to minimize or prevent these major complications. Potential average savings accrued from one patient undergoing EAAA repair rather than RAAA repair ($93,139. 21) can be used to perform screening abdominal ultrasound tests in patients at increased risk of having an AAA.

Carotid screening with duplex ultrasound in elderly asymptomatic patients referred to a vascular surgeon: is it worthwhile?

The purpose of this study is to prospectively determine the outcome of carotid duplex ultrasound screening in patients referred to a vascular surgeon for problems other than carotid disease. During a recent 12-month period, 307 patients age 65 years and older (mean 76 +/- 8 years) were referred to one vascular surgeon for problems other than cerebrovascular disease. Fifty-one percent of the patients were male, 49% were female, 32% were diabetic, 32% were hypertensive, 31% smoked, 20% had coronary artery disease, and 64% had peripheral arterial occlusive disease. All patients underwent a screening duplex ultrasound exam of the carotid arteries as approved by our Institutional Review Board. The results of our study showed that the prevalence of asymptomatic carotid artery stenosis >70% among patients seen by a vascular surgeon for problems other than cerebrovascular disease is high (21%) and is associated with male gender, advanced age, diabetes mellitus and having quit smoking. Continued carotid artery duplex screening is warranted in this patient population greater than age 65 years.

The value and limitations of magnetic resonance angiography of the circle of Willis in patients undergoing carotid endarterectomy.

Magnetic resonance angiography is a useful technique to determine the patency of the circle of Willis when compared with conventional four-vessel angiography. The purpose of this study is to determine whether the integrity of the circle of Willis, assessed by magnetic resonance angiography, provides adequate collateral cerebral circulation during carotid endarterectomy and correlates with internal carotid artery back pressure. Over a recent 20-month period, 35 patients were studied preoperatively with magnetic resonance angiography of the carotid bifurcations of the circle of Willis and the vertebrobasilar system. All patients underwent standard carotid endarterectomy with intraoperative measurement of internal carotid artery back pressure. Patients with an internal carotid artery back pressure < 50 mmHg had an intraluminal shunt placed. Deficiencies in branches of the circle of Willis, the carotid bifurcation and the vertebrobasilar system determined by magnetic resonance angiography were correlated with internal carotid artery back pressure using Fisher's exact test. Only one patient had a completely intact circle of Willis. Eleven of 16 patients (69%) who had an internal carotid artery back pressure < 50 mmHg had an occluded A1 segment of the anterior cerebral artery combined with an occluded posterior communicating artery, whereas only five of 19 patients (26%) who had an internal carotid artery back pressure > 50 mmHg had similar findings (P < 0.03). Severity of occlusive disease of the contralateral internal carotid artery and the basilar artery did not independently predict internal carotid artery back pressure. An occluded anterior branch of the circle of Willis in combination with an occluded posterior branch of the circle of Willis is associated with an internal carotid artery back pressure < 50 mmHg. Although magnetic resonance angiography of the circle of Willis may provide valuable anatomic information, it is not sufficiently accurate to predict the need for carotid shunting and therefore its use cannot be justified on a routine basis.

Clinical experience with superior vena caval Greenfield filters.

PURPOSE: To evaluate the results of superior vena caval (SVC) Greenfield filters in patients at risk for pulmonary embolism (PE) secondary to upper extremity deep venous thrombosis (UEDVT). METHODS: Over a 46-month period, 26 patients (10 men, mean age 67 years, range 25 to 89) with UEDVT in whom anticoagulation was contraindicated (n = 22) or ineffective in preventing recurrent PE or extension of the thrombus (n = 4) were treated with placement of SVC Greenfield filters. RESULTS: One SVC filter was misplaced into the innominate vein but left in place; this vein remains patent after 2 months without evidence of filter migration. Follow-up ranged from 10 days to 46 months (mean 7.8 months). Fifteen (58%) patients died inhospital of causes unrelated to the SVC filter or recurrent thromboembolism (mean time to death 36 days). Of the 11 survivors, follow-up ranged from 1 to 38 months (mean 22). Sequential chest roentgenograms in 9 (82%) patients revealed no filter migration or displacement. No evidence of PE was found in any of the survivors over the course of follow-up. CONCLUSIONS: Insertion of SVC Greenfield filters is a safe and feasible therapy to prevent recurrent thromboembolism in patients with UEDVT who are refractory to or inappropriate for anticoagulation therapy.

Hemodynamic instability following carotid endarterectomy does not affect early discharge.

Over the last few years, there has been increased emphasis on early discharge of patients following carotid endarterectomy in the United States. Recent studies have shown that short-stay hospitalization for carotid endarterectomy may be safe and cost-effective. However, this is not always possible because of reasons that are not clearly delineated. In order to optimize the early discharge of patients following carotid endarterectomy, an analysis of the causes of delayed discharges was performed in the present series. Since hemodynamic instability has been shown to be the most frequent complication following carotid endarterectomy, the authors investigated whether it was an important factor preventing early postoperative discharge. This study reviewed the data of 100 consecutive patients admitted for elective carotid endarterectomy. The incidence of post-carotid endarterectomy hemodynamic instability was 37% (n = 37), with hypertension occurring in 25 patients (68%) and hypotension occurring in 12 patients (32%). Hemodynamic instability tended to occur with the use of general anesthesia as compared with regional anesthesia. Hemodynamic instability did not correlate with pre-existent history of hypertension, nor with the type of drug used when general anesthesia was applied. All the patients were successfully treated either in the recovery room or in a monitored area. The average total length of stay was 1.65 days with 79% of the patients being discharged on the first postoperative day and 21% having delayed discharge ranging from 2 to 15 days (mean 4 days). The main reasons for delayed discharges were cardiac and urinary tract complications. Blood pressure instability accounted for only 2% of cases. Thus, these data show that hemodynamic instability does not significantly affect early discharge.

The effect of tumor necrosis factor binding protein and interleukin-1 receptor antagonist on the development of abdominal aortic aneurysms in a rat model.

PURPOSE: Tumor necrosis factor (TNF), interleukin 1 (IL-1), and matrix metalloproteases have been noted to be elevated in human abdominal aortic aneurysms (AAAs) as compared with normal and occlusive aortic disease. Because TNF and IL-1 have been shown to cause release of proteases that weaken the aortic matrix, it has been suggested that these cytokines may play a central role in the aortic dilatation process. To substantiate this hypothesis, we investigated the effects of TNF and IL-1 antagonists, tumor necrosis factor binding protein (TNF-BP) and interleukin-1 receptor antagonist (IL-1RA), on the development of AAAs in a well-described rat model. METHODS: Isolated segments of infrarenal aorta of 16 rats were perfused with porcine elastase. In the treated group, eight rats were given intravenous TNF-BP prior to elastase perfusion, at 48 hours and at 96 hours. In the control group, eight rats were given only intravenous vehicle at the same time intervals. Isolated segments of infrarenal aorta of an additional 16 rats were perfused with porcine elastase in a similar fashion. In the treated group, eight rats were given intraperitoneal IL-1RA prior to celiotomy and every eight hours. In the control group, eight rats were given only intraperitoneal vehicle at the same time intervals. On the sixth postoperative day, all rats underwent celiotomy and measurement of the infrarenal aortic diameter with a micrometer while the animal was alive. Aortic specimens were collected on day six for hematoxylin and eosin staining, trichrome staining, and gel polyacrylamide gel electrophoresis (PAGE) zymography. RESULTS: TNF-BP was completely able to block post elastase dilation, whereas IL-1Ra seemed to have no effect. Hematoxylin and eosin staining and trichrome staining revealed that animals treated with TNF-BP had less of an inflammatory response and preservation of the elastin and smooth muscles in the media of the aortic wall as compared with animals treated with IL-1RA or vehicle. Zymography was not able to detect significant protease activity in the aortic wall of any of the rats at six days. CONCLUSION: TNF-BP, but not IL-1RA, may inhibit the development of AAAs in this model.