Exercise rehabilitation improves functional outcomes and peripheral circulation in patients with intermittent claudication: a randomized controlled trial.

OBJECTIVE: To determine the effects of a 6-month exercise program on ambulatory function, free-living daily physical activity, peripheral circulation, and health-related quality of life (QOL) in disabled older patients with intermittent claudication. DESIGN: Prospective, randomized controlled trial. SETTING: University Medical (Center and Veterans Affairs Medical Center, Baltimore, Maryland. PARTICIPANTS: Thirty-one of 61 patients with Fontaine stage II peripheral arterial occlusive disease (PAOD) were randomized to exercise rehabilitation and 30 to usual-care control. Three patients from the exercise group and six patients from the control group dropped out, leaving 28 and 24 patients, respectively, completing the study in each group. INTERVENTION: Six months of exercise rehabilitation. MEASUREMENTS: Treadmill distance walked to onset of claudication and to maximal claudication, ambulatory function, peripheral circulation, perceived QOL, and daily physical activity. RESULTS: Compliance with the exercise program was 73% of the possible sessions. Exercise rehabilitation increased treadmill distance walked to onset of claudication by 134% (P < .001) and to maximal claudication by 77% (P < .001), walking economy by 12% (P = .003), 6-minute walk distance by 12% (P < .001), and maximal calf blood flow by 30% (P < .001). Changes in distance walked to maximal pain correlated with changes in walking economy (r = -.50, P = .013) and changes in maximal calf blood flow (r = .38, P = .047). Exercise rehabilitation increased accelerometer-derived daily physical activity by 38% (P < .001); this change correlated with the change in distance walked to maximal pain (r = .45, P = .020). These improvements were significantly better than the changes in the control group (P < .05). CONCLUSION: Improvements in claudication following exercise rehabilitation in older PAOD patients are dependent on improvements in peripheral circulation and walking economy. Improvement in treadmill claudication distances in these patients translated into increased accelerometer-derived physical activity in the community, which enabled the patients to become more functionally independent.

Fenoldopam infusion associated with preserving renal function after aortic cross-clamping for aneurysm repair.

BACKGROUND: Cross-clamping of the descending aorta during operative repairs causes sudden, significant reductions in renal function that may persist well beyond arterial clamp release. Commonly used agents, such as dopamine and mannitol, have not consistently affected renal outcome in these high-risk patients. Fenoldopam mesylate is a novel, highly selective dopamine type-1 agonist that preferentially dilates the renal and splanchnic vasculature, but has not been investigated in patients undergoing prolonged aortic clamping for whom adverse renal outcomes should be more likely. METHODS AND RESULTS: Twenty-two adult patients without significant pre-existing renal dysfunction and presenting for elective repairs of abdominal aortic aneurysms were studied. Fenoldopain mesylate was infused after obtaining baseline values ranging from 0.1 to 1.0 microg/kg/min for the first 24 hours postoperatively to maintain mean arterial pressure +/-25% baseline. Serial renal function indices, including creatinine clearance and electrolyte fractional excretions, were measured at baseline, at aortic clamping and unclamping, and post-clamp release, and were estimated through hospital discharge. Creatinine clearance fell during abdominal exploration and clamping, reaching a nadir with clamp removal. Partial recovery occurred by 2 hours after clamp removal, and returned to baseline values by postoperative day 1 and thereafter. Fractional excretions rose rapidly throughout the operative phase. Total fenoldopam dose was directly related to the baseline creatinine clearance; after clamp removal, creatinine clearance was directly related to the mean arterial pressure at the lowest dose of fenoldopam, and inversely related to the mean arterial pressure at clamp release. CONCLUSIONS: In elderly patients with severe vascular disease undergoing aneurysmal repairs, the use of a fenoldopam infusion in this open-label, uncontrolled trial was associated with a relatively rapid return of renal function to baseline values, despite profound decreases during aortic cross-clamping. Further studies will be necessary to investigate how fenoldopam infusions compare with traditional therapies.

Tibial bypass using complex autologous conduit: patency and limb salvage.

Over an 8-year period, we performed 93 lower extremity bypasses using complex autologous conduits, which included (1) contralateral greater saphenous vein (GSV), (2) composite GSV, (3) superficial femoral vein, (4) lesser saphenous vein, (5) cephalic or basilic veins, and (6) composite-sequential (PTFE and vein) grafts. These grafts represented 16% of all infrainguinal bypasses during this period, and all grafts were performed to treat limb-threatening ischemia. Survival, patency, and limb salvage were examined by the life-table method. Primary graft patency was 46 and 38% at 3 and 5 years. Assisted-primary patency was 62 and 59%, and secondary graft patency rates were 68 and 64% at 3 and 5 years. Twenty-nine bypasses (31%) required revision to restore or maintain patency. The 3-year limb salvage rate was significantly better when revision was performed for graft stenosis than for graft thrombosis (90% vs. 46%, p < 0.05). Overall limb salvage rate was 73% at 5 years. The mortality rate was 5.4% and the 5-year survival was 51%. Complex autologous tibial bypasses provided acceptable long-term limb salvage in patients with severe ischemia and inadequate ipsilateral GSV. The increased operating time and complexity required did not produce prohibitive operative risks. Postoperative graft surveillance in these complex vein bypasses allowed revision in many cases before graft occlusion occurred and significantly improved long-term limb salvage.

Improved functional outcomes following exercise rehabilitation in patients with intermittent claudication.

BACKGROUND: The purposes of this study were to identify predictors of increased claudication distances following exercise rehabilitation in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication and determine whether improved claudication distances translated into increased free-living daily physical activity in the community setting. METHODS: Sixty-three patients were recruited (age, 68+/-1 years, mean +/- standard error). Patients were characterized on treadmill claudication distances, walking economy, peripheral circulation, cardiopulmonary function, self-perceived ambulatory function, body composition, baseline comorbidities, and free-living daily physical activity before and after a 6-month treadmill exercise program. RESULTS: Exercise rehabilitation increased distance to onset of claudication pain by 115% (178+/-22 m to 383+/-34 m; p < .001) and distance to maximal claudication pain by 65% (389+/-29 m to 641+/-34 m; p < .001). The increased distance to onset of pain was independently related to a 27% increase in calf blood flow (r = .42, p < .001) and to baseline age (r = -.26, p < .05), and the increased distance to maximal pain was predicted by a 10% increase in peak oxygen uptake (r = .41, p < .001) and by a 10% improvement in walking economy (r = -.34, p < .05). Free-living daily physical activity increased 31% (337+/-29 kcal/day to 443+/-37 kcal/day; p < .001) and was related to the increases in treadmill distances to onset (r = .24, p < .05) and to maximal pain (r = .45, p < .001). CONCLUSIONS: Increased claudication distances following exercise rehabilitation are mediated through improvements in peripheral circulation, walking economy, and cardiopulmonary function, with younger patients having the greatest absolute ambulatory gains. Furthermore, improved symptomatology translated into enhanced community-based ambulation.

Arterial reconstruction with deep leg veins for the treatment of mycotic aneurysms.

PURPOSE: Mycotic pseudoaneurysms (MPA) remain challenging clinical problems. Primary surgical management includes control of hemorrhage and debridement of the infected arterial wall. Because critical ischemia may develop after arterial resection, revascularization has been a secondary goal of treatment. Standard anatomic graft placement or prosthetic bypass grafting has been compromised by a high rate of recurrent infection. Extra-anatomic reconstruction is preferred, with the basic goals being threefold: (1) the use of autogenous graft material to reduce the risk of reinfection; (2) the avoidance of significant size mismatches; and (3) graft placement that is anatomically inaccessible, because drug abuse causes many of these lesions. This study reviews a recent series of MPAs applying these treatment goals. METHODS: In a 2-year period, the superficial femoral and proximal popliteal veins were used in the repair of eight MPAs of the common femoral (5), common iliac (1), and brachial (1) arteries, and the infrarenal aorta (1). Most patients (5 of 7) were known intravenous drug users, who had a painful pulsatile mass in an injection area. Two patients had systemic sepsis, one patient with an infected common iliac pseudoaneurysm and one patient with an MPA of the infrarenal aorta. The diagnosis of MPA was made by means of duplex/computed tomography scanning and confirmed by means of arteriography in all cases. RESULTS: Obturator bypass grafting was performed by using a reversed deep leg vein in the five femoral MPAs. An ilioiliac, cross-pelvic bypass grafting procedure with a deep vein was used to repair an MPA of the common iliac artery. A deep vein was also used as a "pantaloon" aortobiiliac graft and for a brachial artery repair. Staphylococcus aureus was revealed by means of cultures in nearly all cases. Distal arterial perfusion was normal after reconstruction. Patients had no significant postoperative leg swelling. No new venous thrombosis below the level of deep vein harvest was revealed by means of duplex scanning. There were no septic complications. CONCLUSION: The superficial femoral/popliteal veins may be particularly useful for limb revascularization in patients with MPAs. This autogenous conduit provides an excellent size-match and a suitable length for reconstruction, because peripheral, axial arteries are generally affected. No clinically significant limb morbidity was related to deep vein removal. Late follow-up is challenging in such cases, but will be required to accurately determine the durability of this strategy.

The prevalence of carotid artery stenosis in patients undergoing aortic reconstruction.

BACKGROUND: Coronary artery disease occurs frequently in patients undergoing aortic reconstruction, and it has been presumed that internal carotid artery occlusive disease is also common. This has led to the practice of screening for and repairing significant carotid lesions in asymptomatic patients prior to aortic reconstruction. The purpose of this study was to determine the true prevalence of internal carotid artery disease in these patients. METHODS: The records of 240 patients who underwent duplex ultrasound screening for carotid artery disease prior to aortic reconstruction were reviewed. Surgery was performed for aortic aneurysm (AA) or aorto-iliac occlusive disease (AO). The prevalence of hyperlipidemia and coronary artery disease was similar between the two groups, but tobacco use, hypertension, and diabetes mellitus differed. RESULTS: Internal carotid artery stenosis > or = 50% occurred in 26.7% of the total group (64 of 240 cases). Stenosis > or = 50% was more common in the AO group (40 of 101 cases, 39.6%) than the AA group (24 of 139 cases, 17.3%, P = 0.0001). Severe disease (70% to 99%) was also more common in the AO group than the AA group (9.9% versus 3.6%, P = 0.0464). CONCLUSION: Internal carotid artery disease occurs commonly in patients undergoing aortic reconstruction, and screening is worthwhile. Significant disease is more common in patients with aorto-iliac occlusive disease than in those with aortic aneurysm, although atherosclerotic risk factors occur with varying frequency in the two groups. These findings suggest that additional factors may contribute to the higher prevalence of internal carotid artery stenosis in aorto-iliac occlusive disease.

Duplex ultrasound insertion of inferior vena cava filters in multitrauma patients.

BACKGROUND: Techniques for placement of inferior vena cava (IVC) filters have undergone continued evolution from open surgical exposure of the venous insertion site to percutaneous insertion in most cases today. However, the required transport either to an operating room or interventional suite can be complex and potentially hazardous for the multiply injured trauma patient who may require ventilator support, controlled intravenous infusions, or skeletal immobilization. Increased experience with color-flow duplex scanning for routine IVC imaging and portability of ultrasound equipment have suggested the usefulness of duplex-guided IVC filter insertion (DGFI) in critically ill trauma and intensive care unit (ICU) patients. METHODS: A total of 25 multitrauma/ICU patients were considered for DGIF. Screening color-flow duplex scans were performed on all patients, and obesity or bowel gas prevented ultrasound imaging in 2 cases, leaving 23 patients suitable for DGFI. In each case, the IVC was imaged in the transverse and longitudinal planes. The right renal artery was identified as it passed posterior to the IVC and was used as a landmark of the infrarenal segment of the IVC. All procedures were performed at the bedside in a monitored ICU setting using percutaneous placement of titanium Greenfield filters. Duplex scanning after insertion was used to document proper placement, and circumferential engagement of the filter struts in the IVC wall. An abdominal radiograph was also obtained in each case to confirm proper filter location. Duplex ultrasound imaging was repeated within 1 week of insertion to assess IVC and insertion site patency. RESULTS: DGFI was successful in all cases. The filter was deployed at a suprarenal level in one case, as was recognized at the time of postprocedural scanning. Three patients died as a result of their injuries but there were no pulmonary embolism deaths. Repeat duplex scanning was obtained in 17 patients, and revealed no case of IVC or insertion site thrombosis. CONCLUSIONS: Vena caval interruption can be safely performed under ultrasound guidance in a monitored, ICU environment. In selected multiply injured trauma patients, this will reduce the risk, complexity and cost of transport for these critically ill patients. DGFI also reduces procedural costs compared with an operating room or interventional suite, and eliminates intravenous contrast exposure. Preprocedural scanning is essential to identify patients suitable for DGFI, and careful attention must be paid to the known ultrasonographic anatomical landmarks.

The effect of cigarette smoking status on six-minute walk distance in patients with intermittent claudication.

The purposes of the study were threefold: (1) to compare 6-minute walk performance as a measure of exercise tolerance among three different groups of peripheral arterial occlusive disease (PAOD) patients with intermittent claudication-current smokers, former smokers, and patients who have never smoked; (2) to identify important covariates that might affect the relationship between smoking and exercise in the PAOD population; (3) to determine whether differences among the three groups in 6-minute walk performance persist after statistically controlling for the significant covariates. Recruited into the study were 415 PAOD patients with intermittent claudication between the ages of 42 and 88 years. The self-reported smoking status consisted of 182 current smokers, 196 former smokers, and 37 patients who had never smoked. The authors recorded 6-minute walk distance, a reliable measurement of exercise tolerance in PAOD patients, as well as age, body composition, self-reported ambulatory function, self-reported physical activity, and standard peripheral hemodynamics. Nonsmokers walked significantly farther (413 +/- 14 m; mean +/- standard error) and took more steps (665 +/- 14 steps) than either current (352 +/- 7 m; 563 +/- 9 steps) or former smokers 370 +/- 7 m; 600 +/- 8 steps) (p<0.05). The nonsmokers had a higher ankle-brachial index (ABI) value (0.70 +/- 0.03) than patients who actively smoked 0.62 +/- 0.01 (p<0.03); the authors observed an inverse relationship between smoking history and self-reported physical activity (WIQ Distance Score: nonsmokers 51 +/- 6%, former smokers 38 +/- 3%, and smokers 32 +/- 2%) (p<0.01). From a multivariate perspective, ABI, physical activity, and perceived walking ability were the only independent predictors of 6-minute walk distance. Differences in the adjusted 6-minute walk distance among the nonsmokers (388 +/- 13 m), current smokers (359 +/- 6 m), and former smokers (368 +/-6 m) no longer remained after controlling statistically for these covariates. The findings suggest that 6-minute walk distance is a sensitive measure to detect differences in submaximal exercise performance between smoking and nonsmoking PAOD patients with intermittent claudication. Moreover, the group difference in the 6-minute walk distance is explained by group differences in walking perception, PAOD severity, and physical activity level.

Assessment of ocular perfusion after carotid endarterectomy with color-flow duplex scanning.

PURPOSE: The purpose of this study was to assess the effect of carotid endarterectomy (CEA) on ocular perfusion with the measurement of the ophthalmic artery (OA) and the central retinal artery (CRA) flow velocities with color-flow ocular duplex scanning (ODS). Ocular hemodynamics also were examined in a subset of patients with visual symptoms in an attempt to characterize the origin of the ocular symptoms and their response to surgery. METHODS: Twenty-five patients with internal carotid artery stenoses (>/=70%) underwent 29 CEAs. All the patients underwent ODS for the measurement of the peak systolic velocity (PSV) in the OA and the CRA of the ipsilateral eye before and after CEA. The preoperative and postoperative flow velocities were compared in all the patients and in the patients with and without visual symptoms. RESULTS: The preoperative PSV in the OA was 21.6 +/- 2.2 cm/s and in the CRA was 7.7 +/- 0.7 cm/s. These values were reduced as compared with normative values (OA, 37.8 cm/s; CRA, 10.7 cm/s). After CEA, the PSV increased significantly in both vessels (postoperative OA, 38.6 +/- 2.5 cm/s, P <.0001; postoperative CRA, 12.1 +/- 0.9 cm/s, P =.0008). Fifteen of the 29 CEAs were performed for visual symptoms. The patients with ocular symptoms had significantly lower preoperative PSVs in the CRA as compared with those patients without visual symptoms (CRA with ocular symptoms, 6.5 +/- 0.8 cm/s; CRA with no ocular symptoms, 9.4 +/- 0.9 cm/s; P =.02). The PSV in the OA was not significantly lower in the patients with ocular symptoms. Eight patients (28%) were found to have reversed OA flow before surgery, but only three patients had ocular symptoms. All eight patients had normal antegrade flow in the OA after surgery. CONCLUSION: Severe carotid stenosis may be associated with reduced ocular perfusion, which can be quantitatively evaluated with ODS. Reduced OA and CRA flow velocities are corrected with successful CEA. The patients with ocular symptoms were observed to have significant reductions in CRA flow velocities. Reversed flow in the OA was not a marker for ocular symptoms in this study. ODS can identify global ocular ischemia and may be helpful in the evaluation of patients with atypical visual symptoms or with amaurosis fugax and no evidence of retinal emboli.

Can intrarenal duplex waveform analysis predict successful renal artery revascularization?

PURPOSE: No currently available noninvasive test can preoperatively predict a successful outcome to renal revascularization. Resistance measurements from the renal parenchyma obtained with duplex sonography reflect the magnitude of intraparenchymal disease, and patients with extensive intrarenal disease may respond less favorably to revascularization. To address this question, we reviewed our (primarily) operative experience in patients undergoing renal artery revascularization, and compared the blood pressure (BP) and renal function response with resistance measurements obtained from the kidney both before and after revascularization. METHODS: During a 56-month period, 31 consecutive renal artery revascularizations (25 surgical and 6 percutaneous angioplasties) were performed in 23 patients (21 atherosclerotic, 2 fibromuscular dysplasia). Duplex sonography was performed in each patient before and after revascularization, and parenchymal diastolic/systolic (d/s) ratios were calculated. BP and renal function response to intervention were compared with measurements of intrarenal flow patterns before and after revascularization. RESULTS: Mean parenchymal peak systolic velocity was significantly higher after repair in all patients (pre-repair: 19.5 +/- 1.3, postrepair: 27.2 +/- 1.7; P < .0001). Despite this, there were no statistical differences between preoperative and postoperative parenchymal d/s ratios. A favorable (cured or improved) BP response was seen in 81% (17 of 21) of revascularizations performed for hypertension. Among these successes, parenchymal d/s ratios were in the normal range (ie, > or = 0.30) both before and after repair (mean prerepair: 0.34 +/- 0.03, mean postrepair: 0.31 +/- 0.03; not significant). In 4 patients in which BP failed to improve after intervention, the d/s ratio was abnormal before surgery (< 0.3), and remained so after revascularization (mean preoperative d/s ratio: 0.18 +/- 0.04, mean postoperative d/s ratio: 0.11 +/- 0.04; P = .003). Mean preoperative parenchymal d/s ratios were significantly higher in all patients with a successful BP response when compared with failures (P = .048). Similarly, among patients with single artery repairs, mean preoperative d/s ratios approached significance in successes vs. failures (success: 0.40 +/- 0.03, failure: 0.21 +/- 0.03; P = .054). A decrease in serum creatinine greater than or equal to 20% was seen in 8 of 18 patients (44%) with ischemic nephropathy. These patients also had normal d/s ratios preoperatively (mean 0.39 +/- 0.04), whereas the 10 patients who failed to improve had significantly lower ratios (mean 0.24 +/- 0.03; P = .041). Kidney length did not correlate with d/s ratio. CONCLUSION: Although we do not believe that duplex sonographic measurement of intrarenal flow patterns alone is an accurate means of assessing main renal artery occlusive disease, the resistive indices seem to reflect the magnitude of intraparenchymal disease, and thus may provide important prognostic information for patients undergoing surgical revascularization. Our data suggest that a preoperative d/s ratio below 0.3 correlates with clinical failure relative to BP and renal function responses.

Progressive intermittent claudication is associated with impaired fibrinolysis.

PURPOSE: Acute complications of atherosclerosis such as stroke and myocardial infarction are caused by thrombosis and may be associated with impaired fibrinolytic activity. The current study was performed to determine whether peripheral arterial disease (PAD) and its progression are also associated with impaired fibrinolysis, by measurement of tissue plasminogen activator (tPA, the activator of fibrinolysis) and its inhibitor plasminogen activator inhibitor-1 (PAI-1). METHODS: The study group consisted of 80 men with a mean age of 69 years. This included 18 patients with mild intermittent claudication (MC, pain-free walking distance > or = 200 meters) and 51 patients with severe claudication (SC, walking distance <200 meters). Eleven age- and sex-matched patients without PAD served as controls. All patients had measurements of serum tPA antigen using an enzyme-linked immunoadsorbent assay. Serum levels of tPA and PAI-1 activity were assayed with an amidolytic method. Mean +/- SEM levels of the enzyme levels in patients with progressively more severe PAD were compared with normal controls. RESULTS: Serum PAI-1 activity levels were significantly elevated in both PAD groups compared with normal controls (p < 0.02). There were no significant differences in the PAI-1 activity levels in groups with worsening degrees of PAD. There was a significant decrease in tPA activity levels in patients with SC (p = 0.01) relative to those with MC and the normal subjects. There was also a significant increase in tPA antigen level in the patients with SC compared with those with MC and the control subjects, as well as a significant inverse correlation between tPA antigen levels and pain-free walking time in patients with claudication (p = 0.001). CONCLUSIONS: All patients with PAD in this study had significant reductions in endogenous fibrinolytic activity. Patients with SC had more impaired fibrinolytic activity than those with MC and the control subjects, suggesting that the progression to more severe levels of PAD may be associated with worsening endogenous fibrinolysis.

Regression of proximal deep venous thrombosis is associated with fibrinolytic enhancement.

PURPOSE: Recanalization after acute lower limb deep venous thrombosis (DVT) is well documented, but the precise mechanism and timing of these events has not been well characterized. Regression of DVT has been presumed to result from activation of the endogenous fibrinolytic system. This study was performed to compare measurements of the enzymatic components of the intrinsic fibrinolytic system (tissue plasminogen activator [tPA], plasminogen activator inhibitor [PAI-1]) with the observed morphologic changes in thrombosed venous segments using venous duplex ultrasound scanning (VDUS) at intervals after diagnosis of acute DVT. METHODS: Nineteen patients with acute DVT underwent serial VDUS to assess regression of thrombus at intervals of 1 to 2 weeks, 3 to 6 weeks, 8 to 12 weeks, and 24 to 36 weeks. The extent of thrombus in each limb was quantitated at each interval by VDUS of the residual thrombus present in each of five major axial venous segments: the common femoral, superficial femoral, profunda femoris, popliteal, and tibial veins. Thrombus scores for the group at each interval were compared with baseline scores at diagnosis to calculate the percent residual thrombus. Endogenous fibrinolytic activity was determined at the same intervals by serologic assay of the biologic activities of tPA and its inhibitor PAI-1. RESULTS: Thrombus regression was evident by VDUS at 1 to 2 weeks and progressed such that only 26% of residual thrombus remained at 24 to 36 weeks. Complete resolution of thrombus occurred in 10 of 18 patients (56%) who completed the 9-month study. Baseline mean tPA activity was 0.60 +/- 0.07 IU/ml and increased to 1.31 +/- 0.26 IU/ml at 1 to 2 weeks (p = 0.014). tPA activity remained significantly elevated through the 8 to 12 week interval and returned to baseline at 24 to 36 weeks. PAI-1 activity was elevated relative to an age-matched population at baseline (23.1 +/- 1.8 AU/ml) but remained unchanged throughout the study period. Progression of thrombus was observed in three patients (15.8%). Patients who experienced propagation of thrombus did not have the increased tPA activity that appeared to mark activation of intrinsic fibrinolysis. CONCLUSIONS: Regression of acute DVT begins early and continues for at least 9 months. It is accompanied by significant enhancement of the endogenous fibrinolysis, which appears to be primarily mediated by increased tPA activity. Patients who have thrombus propagation in spite of standard antithrombotic therapy may have failure of activation of endogenous fibrinolysis.

A randomized, prospective trial of deep venous thrombosis prophylaxis in aortic surgery.

OBJECTIVES: To study the incidence of postoperative deep venous thrombosis (DVT) in patients undergoing elective aortic reconstruction and to determine if aggressive DVT prophylaxis would reduce the incidence of DVT in these patients. DESIGN: Randomized, prospective trial. SETTING: University hospital and Veterans Affairs hospital. PATIENTS: One hundred patients undergoing aortic reconstruction for aneurysmal or occlusive disease randomized to receive DVT prophylaxis (treatment group) or no prophylaxis (control group). Exclusion criteria included a history of DVT, long-term anticoagulant use, or a malignant neoplasm. During the study period, 12 patients were ineligible for follow-up. Ninety-eight patients completed the trial, including 50 patients in the treatment group and 48 patients in the control group. Two patients in the control group died postoperatively of unrelated causes. INTERVENTION: Patients in the treatment group received DVT prophylaxis using a combination of low-dose heparin sodium therapy (5000 U every 12 hours) and calf-length intermittent mechanical compression devices. Control patients received no DVT prophylaxis. MAIN OUTCOME MEASURES: The occurrence of acute lower extremity DVT diagnosed by interval venous duplex ultrasound scan surveillance performed on postoperative days 1, 3, and 7. RESULTS: The overall incidence of proximal DVT in this study was 2%. One case of DVT occurred in the treatment group, and the other one occurred in the control group. There was no statistically significant difference (P = .99) in the incidence of DVT between the 2 groups. One patients in the control group had a nonfatal pulmonary embolus (1% of the patients overall). CONCLUSIONS: The incidence of proximal DVT in patients undergoing elective aortic reconstruction is low compared with patients undergoing other major intraabdominal general surgical procedures. The use of aggressive DVT prophylaxis did not reduce the risk of postoperative proximal DVT in this study. The selective use of DVT prophylaxis in patients undergoing elective aortic surgery should be based on associated concomitant or evolving risk factors.

Defective fibrinolysis occurs after infrainguinal reconstruction.

PURPOSE: Early thrombosis of infrainguinal bypass grafts may occur as a result of hypercoagulable states. Major surgical procedures are known to induce a procoagulant state that is manifested in part by reduced endogenous fibrinolytic activity or fibrinolytic shutdown. This study was performed to assess the timing and biologic mechanism of fibrinolytic shutdown after infrainguinal bypass procedures by direct assay of the serologic markers of in vivo fibrinolytic activity. METHODS: Twenty patients underwent infrainguinal bypass procedures under epidural anesthesia. Endogenous fibrinolytic activity was assessed by measurement of tissue plasminogen activator (tPA) and its naturally occurring inhibitor, plasminogen activator inhibitor (PAI-1). The tPA and PAI-1 antigen (total protein) levels were determined using enzyme-linked immunosorbent assays, and measurements of in vivo biologic activity were performed using an amidolytic method. Measurements of tPA and PAI-1 were made before surgery, after surgery, and on postoperative days 1, 2, 7, and 30. RESULTS: The mean preoperative PAI-1 activity was 20.6 +/- 1.4 arbitrary units (AU)/ml, which was higher than that of an age-matched population without severe atherosclerosis. PAI-1 activity rose significantly after surgery (29.6 +/- 2.2 AU/ml; p = 0.002) and remained elevated through the second day after surgery. Preoperative tPA activity level was 2.04 +/- 0.59 IU/ml and fell to 0.79 +/- 0.23 IU/ml (p = 0.046) immediately after the bypass procedure. All serologic indicators of fibrinolytic shutdown returned to baseline levels by 72 hours after surgery. No early graft thrombosis or other atherothrombotic complications occurred in these study patients. CONCLUSIONS: Defective endogenous fibrinolytic activity occurs in the early postoperative period after infrainguinal bypass grafting procedures. Diminished endogenous fibrinolytic activity in these patients appears to be mediated by a combination of reduced tPA activity and significantly increased PAI-1 activity. No practical method is available to directly treat postoperative fibrinolytic shutdown, but postoperative antithrombotic therapy may be useful during this period to prevent early graft occlusion related to a relative hypercoagulable state.

Early duplex scan evaluation of four vena caval interruption devices.

PURPOSE: Transvenous inferior vena cava (IVC) filters are used successfully for prevention of pulmonary embolism (PE), but early thrombotic complications such as insertion site thrombosis (IST) and inferior vena cava thrombosis (IVCT) may occur after placement. The frequency of these complications has been uncertain particularly for the wide variety of newer devices. This study was performed to prospectively evaluate IST and IVCT with color-flow venous duplex ultrasound scanning after four IVC filters were placed: the birds' nest filter, the titanium Greenfield filter, the stainless steel Greenfield filter, and the Simon nitinol filter. METHODS: Percutaneous IVC filters were placed in 174 patients over a 21-month period. A birds' nest filter was used in 39 (22%) cases, a titanium Greenfield filter in 67 (39%) cases, a stainless steel Greenfield filter (25%) in 43 patients, and a Simon nitinol filter in 25 (14%) cases. Filters were placed for major deep venous thrombosis in 113 (63%) patients, after PE in 26 (15%) patients, and with prophylaxis in 35 (20%) patients. All patients had color-flow venous duplex ultrasound scanning of the insertion site and the inferior vena cava 7 to 10 days after placement or before discharge to document IST or VCT. RESULTS: Early IST occurred in 43 (24.7%) cases, and early IVCT was observed in 20 (12%) cases in this series. No significant difference was found in the incidence of IST or IVCT among the four filter types used. The incidence of IVCT was significantly higher in patients having filters placed for PE. Men were more likely to receive a prophylactic filter than women in this study, but thrombotic complications were not related to patient sex. Thrombosis was seen with equal frequency at all insertion sites used. No patient died of PE after filter placement during the study period. CONCLUSIONS: The incidence of thrombotic complications for all devices was higher than has generally been reported. No IVC filter used in this study demonstrated superior performance with regard to these thrombotic complications. As vena cava interruption devices are developed or significantly modified, prospective objective analysis of associated thrombotic complications will allow logical selection for clinical use.

Prospective surveillance for perioperative venous thrombosis. Experience in 2643 patients.

BACKGROUND: Patients who undergo neurosurgical procedures are at high risk for perioperative deep vein thrombosis (DVT) and pulmonary embolism (PE), which have been reported in 6% to 43% of these patients. OBJECTIVES: To (1) determine the utility of prospective DVT surveillance in patients who undergo neurosurgical procedures by using venous duplex ultrasound scanning (VDUS), (2) assess the efficacy of DVT prophylaxis (elastic stockings and intermittent pneumatic compression), (3) identify subgroups of patients who are at higher risk, and (4) determine whether DVT surveillance would reduce the incidence of fatal PE. DESIGN: All patients had undergone preoperative VDUS of both lower extremities, and postoperative VDUS was performed on days 3 and 7, and weekly thereafter until patients were ambulatory or discharged. PATIENTS: During a 5-year period, 2643 patients who underwent neurosurgical procedures were enrolled in prospective DVT surveillance. SETTING: University-affiliated community hospital. RESULTS: Acute DVT was diagnosed in 147 (5.6%) of the 2643 patients. Eighty-one percent of the patients with acute DVT were asymptomatic at the time of diagnosis. Deep vein thrombosis developed de novo in the proximal veins in 98% of the patients. Patients in whom a craniotomy was done had a significantly higher risk for DVT (7.7%, P = .006), and patients who underwent cervical or lumbar spinal surgical procedures had a significantly lower risk (1.5%, P < .001). Among those patients in whom a craniotomy was performed for treatment of a tumor and who had DVT, 87% had malignant neoplasms. Significant lower-extremity neuromotor dysfunction was present in 69% of all patients with DVT, and this finding predominated among patients with DVT in the subgroups with a lower risk. A PE was diagnosed in 5 patients (0.19%) while they were hospitalized, and a PE was fatal in 2 (0.07% of all patients). CONCLUSIONS: Most perioperative DVTs were clinically silent and formed spontaneously in proximal venous segments where there would be a risk for a PE. The overall incidence of DVT (5.6%) was low, suggesting effective DVT prophylaxis. Patients who underwent spinal surgical procedures were at a significantly lower risk for DVT, and future surveillance is not indicated in this patient group unless other conditions exist (paralysis, malignancy). Patients in whom a craniotomy was performed had a significantly higher risk of DVT, particularly when other risk factors existed. The low incidence of a fatal PE (0.07%) reflected that early detection and treatment of proximal DVT were facilitated by prospective VDUS surveillance in these patients.

Venous hemodynamics during impulse foot pumping.

PURPOSE: This study was designed to measure the effect of intermittent pneumatic compression of the plantar venous plexus on popliteal vein (PV) and common femoral vein (CFV) velocities measured by duplex ultrasound scanning. METHODS: Thirty lower limbs in 15 healthy volunteers had venous duplex scanning measurement of PV and CFV velocities before and during foot pumping with an arteriovenous impulse foot pump system. Venous velocities were measured at two pump pressure settings (100 mm Hg, 200 mm Hg) and during two pump impulse durations (short = 1 second, normal = 3 seconds). All limbs were examined with the subjects in the supine position, and then measurements were repeated with subjects in the 15-degree reverse Trendelenburg position. The mean maximum venous velocity (MVV) produced by foot pumping was compared with resting venous velocity at each anatomic location and for each technologic variable. RESULTS: Impulse foot pumping produced a statistically significant increase in MVV in both the PV and the CFV compared with resting velocities. This significant increase was observed for both pressure settings and both impulse durations, and no differences produced by these two individual variables could be detected. The increase in MVV produced by foot pumping was similar for limbs in the supine position and those examined in the reverse Trendelenburg position. The percentage increase in MVV produced by foot pumping was significantly higher in the PV than in the CFV. CONCLUSIONS: Intermittent pneumatic compression of the plantar venous plexus produces measurable increases in venous outflow from the lower limbs of normal subjects. This study seems to justify further evaluation of the effectiveness of this technique for mechanical deep venous thrombosis prophylaxis in selected high-risk patient groups.

Salvage of renal allograft function and lower extremity venous patency with thrombolytic therapy: case report and review of the literature.

Five months after a cadaveric renal transplants a 69-year-old man was admitted with caval, iliac, and renal allograft vein thrombosis that occurred in the setting of a previously placed caval filter. The patient's urine output and renal function deteriorated rapidly. Thrombolytic therapy with urokinase was begun, and lysis of the thrombus occurred in 72 hours. The patient's renal function returned to baseline, and the transplant was salvaged. Moreover lower extremity venous patency and valvular function were maintained. We report the case and review the literature on thrombolytic therapy for renal allograft vein and lower extremity deep venous thrombosis.

Femorofemoral bypass for aortofemoral graft limb occlusion: a ten-year experience.

PURPOSE: Aortofemoral bypass (AFB) is a durable reconstruction; however, graft limb occlusion occurs in 10% to 20% of patients and results in limb ischemia. Treatment of AFB limb occlusion has been debated, but many recommended femorofemoral bypass (FFB). FFB grafts have had excellent patency rates. The durability of FFB specifically for AFB limb occlusion has not been reported. This study retrospectively examined a 10-year experience with FFB for AFB limb occlusion to determine FFB performance. METHODS: Between 1982 and 1992, FFB was performed on occluded AFB limbs in 22 patients (14 men and 8 women). Reoperation was performed for disabling claudication in five cases, but the remaining 17 patients (77%) had critical limb ischemia. FFB originated from the contralateral patent AFB limb in all cases. Distal anastomosis was to the common femoral artery (n = 8) or the profunda femoris (n = 14). FFB graft patency was confirmed by direct Doppler arterial examination over a mean follow-up of 47 months. RESULTS: The cumulative life-table primary patency rate of FFB was 54% at 5 years. Reoperative procedures performed in nine cases resulted in a secondary patency rate of 84% at 5 years. The limb salvage rate was also 84% at 5 years, reflecting the impact of successful reoperation. Major amputations (two below-knee, one above-knee) were necessary in only three cases. There were no perioperative deaths after FFB, and the cumulative 5-year survival rate was 77%. CONCLUSION: Aortic graft limb occlusion occurs less frequently than failure of infrainguinal grafts making the success of specific reoperative strategies difficult to document reliably. This study suggests that FFB is a safe and durable alternative for AFB limb failure. An aggressive policy of reoperation has resulted in successful extension of FFB graft function and an excellent rate of limb salvage.