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Vascular and Interventional Radiology |
1 From the Department of Radiology, Medical College of Wisconsin, Froedtert Memorial Lutheran Hospital, Milwaukee (M.W.M., G.R.S., S.H.H.); the Department of Vascular Surgery, University of Washington Harborview Medical Center, Seattle, (M.H.M.); the Department of Radiology, Montefiore Medical Center, Bronx, NY (J.C.); and the Department of Vascular Surgery, Loyola University Medical Center, Maywood, Ill (N.L.). From the 1997 RSNA scientific assembly. Received May 29, 1998; revision requested July 16; final revision received August 25; accepted October 13. Address reprint requests to M.W.M., Wisconsin Heart and Vascular Clinic, Ste 575, 2801 W Kinnickinnic River Pkwy, Milwaukee, WI 53215.
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Abstract |
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 TOP Abstract IntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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MATERIALS AND METHODS: From a registry of patients (n = 473) with symptomatic lower limb DVT, results of 312 urokinase infusions in 303 limbs of 287 patients (137 male and 150 female patients; mean age, 47.5 years) were analyzed. DVT symptoms were acute (
10 days) in 188 (66%) patients, chronic (>10 days) in 45 (16%), and acute and chronic in 54 (19%). A history of DVT existed in 90 (31%). Lysis grades were calculated by using venographic results.
RESULTS: Iliofemoral DVT (n = 221 [71%]) and femoral-popliteal DVT (n = 79 [25%]) were treated with urokinase infusions (mean, 7.8 million IU) for a mean of 53.4 hours. After thrombolysis, 99 iliac and five femoral vein lesions were treated with stents. Grade III (complete) lysis was achieved in 96 (31%) infusions; grade II (50%–99% lysis), in 162 (52%); and grade I (<50% lysis), in 54 (17%). For acute thrombosis, grade III lysis occurred in 34% of cases of acute and in 19% of cases of chronic DVT (P < .01). Major bleeding complications occurred in 54 (11%) patients, most often at the puncture site. Six patients (1%) developed pulmonary emboli. Two deaths (<1%) were attributed to pulmonary embolism and intracranial hemorrhage. At 1 year, the primary patency rate was 60%. Lysis grade was predictive of 1-year patency rate (grade III, 79%; grade II, 58%; grade I, 32%; P < .001).
CONCLUSION: Catheter-directed thrombolysis is safe and effective. These data can guide patient selection for this therapeutic technique.
Index terms: Interventional procedures, complications, 93.1265 • Thrombolysis, 93.1265 • Veins, extremities • Veins, thrombosis, 93.751
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Introduction |
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TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Early thrombus removal is a logical approach to improve the long-term outcome of iliofemoral DVT. Interventional treatment strategies have included systemic thrombolytic therapy, surgical thrombectomy, and catheter-directed thrombolysis (1–3).
Lytic therapy is attractive, because it can potentially help achieve restoration of the lumen and removal of the thrombus lining the venous valves. Two goals may be achieved: relief of venous outflow obstruction and preservation of valve function, both of which are established determinants of postthrombotic syndrome (4). In 1994, Semba and Dake (3) reported their experience with 22 patients with acute DVT who were treated with catheter-directed thrombolysis. Their data prompted the development of a Venous Registry, which included data from 63 centers that were willing to prospectively submit detailed case reports to a data collection center. The purpose of this article is to report the initial results of this project, which started in 1995. The purpose of this study was to evaluate catheter-directed thrombolysis for the treatment of symptomatic lower extremity DVT.
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MATERIALS AND METHODS |
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TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Study Patients
Patients with documented acute (10 days) or chronic (>10 days) lower extremity DVT were eligible for enrollment in the registry. Exclusion criteria included isolated infrapopliteal thrombosis, thrombosis after primary thrombectomy, and contraindications to the use of anticoagulation, contrast media, or thrombolytic agents. Contraindications to thrombolytic agents included active internal bleeding, recent cerebrovascular accident, allergy to thrombolytic agents, recent major surgery, recent serious gastrointestinal bleeding, recent serious trauma, severe hypertension, pregnancy, bacterial endocarditis, possibility of intracardiac thrombus, and coagulopathy.
Informed consent for participation in the study was obtained according to the guidelines of the institutional review boards for human subjects at the participating study centers.
Technique
The physician who performed the procedure selected the catheterization technique for thrombolysis. The venous access sites included the right or left internal jugular vein, the common femoral vein, the popliteal vein, and a pedal vein. Over time, the ipsilateral popliteal venous approach became the access site of choice.
In the typical case, with the patient prone on the angiographic table, the popliteal vein was accessed, under ultrasonographic (US) guidance, with a small-gauge echogenic needle to avoid inadvertent puncture of the adjacent popliteal artery. A 5-F sheath commonly was inserted through which all subsequent catheter and wire exchanges were performed. Urokinase was the thrombolytic agent in all cases. Infusion was performed by using a coaxial catheter and infusion wire and/or a multiple–side-hole system. Lysis progress was monitored at venography at varying intervals determined by the operator. The starting and ending times of thrombolysis, as well as the concentration and total amount of urokinase administered, were recorded. By agreement, the operator terminated the procedure when no additional lysis was achieved within the final 12 hours. Self-expandable metallic stents (Wallstent; Schneider, Minneapolis, Minn) were often used to treat lesions that had been obscured by thrombus but were "uncovered" after thrombolysis, particularly at the level of the iliac veins. Inferior vena cava (IVC) filters were placed before or after the lytic infusions in some patients, at the discretion of the attending physician. Heparin was administered systemically during the procedure and/or after lysis, at the discretion of the physician in charge. No strict anticoagulation protocol was mandated.
Laboratory parameters determined before and after lysis also were recorded during the patient's hospital course; these parameters included hematocrit levels, prothrombin time, activated partial thromboplastin time, and international normalized ratio. Warfarin sodium administration was routinely started prior to hospital discharge and was recommended to continue for 6 months. Settings for patient care during the administration of thrombolytic agents included an intensive care unit, a step-down unit, or a standard inpatient ward.
Data Collection
Detailed data collection forms, on which the institution and the physician(s) were identified, were submitted. A complete history and diagnostic evaluation were obtained in all patients prior to thrombolysis. Also noted were the date of hospital admission; the occurrence, extent, and duration of recent DVT; the presence of pain, edema, inflammation, phlegmasia cerulea dolens, and coagulopathy; and previous surgical procedures. If applicable, a prior documented DVT event also was recorded. Venography was performed in all patients to determine the extent of thrombosis. Presence of thrombus before and after lysis in all segments from the IVC to the popliteal vein was recorded by the radiologist who performed the procedure.
Procedure-related complications were defined as any event or condition secondary to lysis or anticoagulation therapy that prolonged intervention or hospitalization. Major complications included bleeding or hematoma necessitating transfusion, PE, a neurologic event, and death. Minor complications included minimal bleeding or hematoma, fever, nausea, and vomiting.
Assessment of Venous Patency
Duplex US follow-up evaluations occurred at the time of hospital discharge and at 4–6 weeks, 3 months, 6 months, and 1 year after lysis. All duplex US evaluations were conducted in the 15° reverse Trendelenberg position. Spontaneous and phasic flow, proximal and distal augmentation, compressibility, and existence of thrombus were measured on B-mode images with Doppler spectra in all affected segments.
The venograms were reviewed, scored, and graded for each infusion by using a modification of the reporting standards for venous disease described by Porter and Moneta (5). A thrombus score was calculated for seven venous segments: the IVC, the common iliac vein, the external iliac vein, the common femoral vein, the proximal portion of the superficial femoral vein, the distal portion of the superficial femoral vein, and the popliteal vein. The thrombus score was 0 when the vein was patent and completely free of thrombus, 1 when partially occluded, and 2 when completely occluded. The total thrombus score before and after lysis was then calculated by adding the scores of the seven venous segments before and after thrombolysis. The difference between the pre- and postlysis thrombus scores divided by the prelysis score resulted in the percentage of thrombolysis achieved, which was then classified into three groups for analysis: grade I for lysis of less than 50%, grade II for lysis of 50%–99%, and grade III for 100%, or complete, lysis (Table 1). The degree or percentage of thrombolysis was calculated after completion of treatment, which included lysis and any additional adjunctive procedure such as deployment of metallic stents used to treat lesions uncovered after thrombolysis (Figs 1, 2).
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2 test for comparison of proportions of categoric variables was used to test statistical significance. A P value of less than .05 was used as a threshold for statistical significance. |
RESULTS |
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Of the 287 evaluated patients, 137 (48%) were male patients and 150 (52%) were female patients. The average age was 47.5 years (age range, 1–98 years). At the time of presentation, 264 (92%) patients had pain, 272 (95%) had edema, and 252 (88%) had both pain and edema. Twenty-six (9%) patients presented with phlegmasia cerulea dolens. Acute symptoms were present in 188 (66%) patients, and chronic symptoms were present in 45 (16%). In the remaining 54 (19%) patients, there was acute (10 days) worsening of pain, edema, or both, in a limb with chronic symptoms (>10 days). This latter category was defined as both chronic and acute. In 90 (31%) patients, there was a history of DVT. The left limb was more frequently involved (61% vs 39%, P < .01).
Technique of Thrombolysis and Venographic Thrombus Location
Catheter-directed thrombolysis was the technique used for 306 (98%) of 312 infusions. A pedal (systemic) infusion was used for 60 (19%) infusions; the systemic infusion was used as an adjunct to catheter-directed thrombolysis in 54 (17%) or as sole therapy in six (2%) of 303 limbs. Primary venous access sites used for thrombolysis included the popliteal vein in 42% of infusions, the ipsilateral or contralateral common femoral vein in 28%, or the internal jugular vein in 21%. Other venous access sites, such as the posterior tibial vein at the ankle or a superficial vein at the calf level were directly punctured in 12% of infusions to achieve catheter access into a tibial vein and/or the popliteal vein (Table 2).
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The duration of lytic therapy for the pedal vein (systemic) infusion group (n = 60) was significantly longer when compared with that in the group treated with catheter-directed thrombolysis alone (n = 252): 67.8 hours versus 48.0 hours (P < .001). The amount of urokinase infused also differed between the two groups: 9.95 million IU for pedal infusion versus 6.77 million IU for catheter-directed thrombolysis alone (P < .001).
Venographic Thrombus Score and Lysis Grade
On the basis of the lysis grading method described earlier, complete lysis (grade III) was achieved in 96 (31%) of 312 infusions, 50%–99% lysis (grade II) was achieved in 162 (52%) infusions, and less than 50% lysis (grade I) was achieved in 54 (17%) infusions (Table 4). Therefore, the combined frequency of grade II and grade III lytic outcomes ("marked lysis") occurred in 83% of infusions. There was no difference in the degree of lysis between cases of iliofemoral DVT and cases of femoral-popliteal DVT.
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10 days) cases, the prevalence of complete lysis (grade III) was 34% as compared with 19% in cases of a history of chronic DVT (>10 days) (P < .01). Conversely, grade I lysis (<50% lysis) occurred more frequently in chronic cases than in acute cases (32% vs 13%, P < .01). These findings were independent of the venographic location of thrombus, although no patient with chronic femoral-popliteal DVT achieved complete lysis. In patients who presented with acute worsening of chronic symptoms (categorized as both acute and chronic), the lysis grades were similar to those obtained in patients with acute symptoms.
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Lysis Grade and Infusion Technique
In the 252 limbs treated with thrombolysis alone, without concomitant pedal infusion, grade III lysis occurred more frequently than it did in the 60 limbs treated systemically (33% vs 22%, P < .03); the reverse was true for grade I lysis (15% vs 28%, P < .03). However, when the six limbs treated with a pedal infusion alone were excluded, there was no significant difference between the two groups. Of the six pedal infusions, five were failures (grade I lysis) and one resulted in a grade II lysis.
Continued Patency
For all infusions, the primary patency rate was 65% and 60% at 6 and 12 months, respectively (Fig 3, Table 6). Patency at 1 year was more likely to be maintained in patients with iliofemoral DVT than in patients with femoral-popliteal DVT (64% vs 47%, P < .01) (Fig 4, Table 7). After lysis, the venographic grade of thrombolysis was a major predictor of long-term patency, with significant benefits in completely lysed limbs, irrespective of thrombus location (Fig 5, Table 8): At 12 months, 79% of limbs with grade III (complete) thrombolysis remained patent, as compared with 32% of limbs with grade I lysis (P < .001). In limbs with acute iliofemoral DVT, patency was maintained in 85% at 1 year, if complete (grade III) lysis had been achieved; for grade II and grade I lysis, patency was maintained in 66% and 36%, respectively, at 1 year.
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Complications
Major bleeding complications were reported in 54 (11%) of 473 patients included in the registry. Of those, 21 (39%) occurred at the venous insertion site, and seven (13%) resulted from a retroperitoneal hematoma. In another 15 (28%) patients, other bleeding complications were recorded; these complications involved the musculoskeletal, gastrointestinal, or genitourinary systems. In the remaining 11 (20%) patients, the source of bleeding was not reported by the investigator. No immediate deaths were reported as a result of a major bleeding complication.
Minor bleeding events were reported in 77 (16%) of 473 patients. The majority of these events (n = 40 [52%]) occurred at the venous entry site of the catheter delivery system. Bleeding complications occurred with equal frequency in both the evaluated and the nonevaluated patient groups.
Neurologic complications included one fatal intracranial hemorrhage and one subdural hematoma, which was treated with surgical evacuation, for a frequency of major neurologic complications of 0.4%. PE occurred in six (1%) patients. One patient experienced a fatal PE, confirmed at autopsy, 16 hours after the start of the urokinase infusion. Thus, two patients died as a result of thrombolysis, for a mortality rate of 0.4%.
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DISCUSSION |
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TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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The current standard of care includes systemic anticoagulation with heparin followed by therapy with warfarin sodium (11). Such a regimen, however, does not promote lysis to reduce the thrombus load, nor does it contribute to restoration of venous valve function. Anticoagulation alone, therefore, does not protect the limb from postthrombotic syndrome, which can occur months to years after the acute thrombotic event (7).
Thrombolysis is a potentially attractive form of therapy because it provides the opportunity for prompt restoration of venous patency and preservation of venous valve function. This therapy can potentially help prevent long-term sequelae of DVT. There is published evidence that thrombolytic agents, even when administered systemically, are superior to standard anticoagulation therapy for achieving early lysis of thrombus. In a pooled analysis of the results from 13 randomized studies, Comerota and Aldridge (1) found that only 4% of patients treated with heparin had substantial or complete lysis as compared with 45% of patients randomly assigned to receive systemic streptokinase therapy. In similar fashion, at a review (12) of pooled data from six trials judged to have been properly randomized, systemic thrombolysis was 3.7 times more effective in producing some degree of lysis than was heparin. Despite these results, progress was hindered, probably because of the use of systemic administration, where the drug does not reach the thrombus in sufficient concentration to provide optimal results.
The report by Semba and Dake (3) in 1994 provided early insight on the potential role of catheter-directed thrombolytic techniques. They reported complete lysis in 72% of patients, with concomitant resolution of symptoms. Delivery of the thrombolytic agent directly into the thrombus offers substantial advantages over systemic administration of a thrombolytic agent, which may fail to reach and penetrate an occluded venous segment. Because thrombolytic agents activate plasminogen in the thrombus, delivery of the drug to that site enhances its effectiveness. By focusing the delivery of higher concentrations of the drug, lysis rates can be improved, the duration of treatment can be reduced, and complications associated with the exposure of the patient to systemic thrombolytic therapy may be reduced. The progress of thrombolysis can be monitored with direct imaging techniques, and lesions that potentially contribute to the thrombosis can be identified. Defects such as stenosis of the common iliac vein can be treated by means of balloon angioplasty with or without the placement of endovascular stents.
The Venous Registry was established to assemble and critically analyze results in a large number of patients with lower extremity DVT treated with endovascular methods in a spectrum of clinical settings. These data are intended to serve as the foundation for the development of the controlled clinical trials that will be necessary to firmly establish the role of thrombolysis in the treatment of this common disorder. Results derived from the registry have demonstrated that the methods used to deliver the lytic agent will affect the early anatomic outcome. In six limbs treated with a pedal infusion without thrombolysis, substantial lysis occurred in only one limb, for a failure rate in excess of 80%. With catheter-directed thrombolysis, the frequency of substantial lysis was 83%, which includes a complete lysis rate of 33%. These findings underscore the need to deliver urokinase directly to the thrombus by using catheter-directed techniques. Systemic infusions, even in conjunction with catheter-directed thrombolysis, should be abandoned because they add to the infusion time and to the total dose of urokinase administered, without yielding better grades of lysis.
The popliteal vein was the most common venous access site. It allows antegrade catheter traversal of the deep venous valves, which can be difficult and potentially traumatic to the leaflets when retrograde passage is used. In addition, chronic lesions are often encountered at the iliocaval junction, even in patients with acute DVT, which cannot predictably be traversed with a cephalic approach from the right internal jugular vein or the contralateral femoral vein. The popliteal vein, punctured under US guidance, is recommended to be the standard access site in most patients.
After thrombolysis, objective and reproducible methods should be used to evaluate venographic studies. With the computation of a thrombus score assigned to each venous segment before and after thrombolysis, a percentage of lysis can be objectively derived to allow grading of thrombolysis. The degree of lysis was found to be a significant predictor of early and continued patency. Seventy-five percent of limbs in which complete lysis was achieved remained patent at 1 year as compared with 32% of limbs in which grade I (<50%) lysis was achieved. In general, acute DVT was predictive of a better lysis grade when compared with chronic DVT, although substantial lysis could be achieved in patients with chronic iliofemoral DVT. When isolated femoral-popliteal DVT was present for more than 10 days, no infusion achieved complete lysis.
On the basis of these data, catheter-directed thrombolysis should be offered to patients in whom complete lysis can be anticipated. In general, an acute thrombotic event in a patient without a history of DVT will most likely yield a favorable grade of lysis, which in turn will be predictive of continued patency. Catheter-directed thrombolysis should only be proposed when femoral-popliteal DVT has occurred less than 10 days from the time lytic therapy is available. It is important to note that the age of the thrombus cannot be predicted on the basis of the duration of symptoms alone; therefore, even in patients with acute symptoms, older thrombus may be present in the deep veins. This in turn may help explain why grade II lytic events were common venographic findings, even in patients who presented with acute symptoms of DVT.
In the registry data, iliofemoral DVT accounted for 71% of symptomatic limbs, and the left common iliac vein was the most frequent site of thrombosis. In surgical series (2,13) in which thrombectomy was used to treat acute iliofemoral DVT, spurlike lesions were detected in as many as 62% of patients. Self-expandable metallic stents may prove to be a valuable adjunct when thrombolysis uncovers a stenosis of an iliac vein. Ninety-nine stent procedures were necessary for the adequate reestablishment of iliac venous outflow in 221 patients who were treated for iliofemoral DVT. Although the effectiveness of stents has not yet been proved, they may be the best method for ensuring long-term patency in treated iliac venous segments. Stent placement in the femoral-popliteal venous segments is not recommended, because the patency results were dismal. Four of five (80%) infrainguinal venous stents did not remain patent beyond a mean of 42 days.
Major bleeding complications were primarily related to the catheter insertion site and were noted in 21 (4%) of the 473 patients. Cautious needle access under US guidance is mandatory to avoid inadvertent puncture of adjacent vessels such as the popliteal artery or the common carotid artery. Fifteen (3%) other bleeding complications were recorded; these involved the musculoskeletal system and gastrointestinal and genitourinary tracts. Spontaneous retroperitoneal bleeding attributable to the lytic agent occurred in seven (1%) of 473 patients. This frequency is comparable to the three reported (4) retroperitoneal hemorrhages in a series of 199 patients who received intravenous heparin for 5 days prior to long-term oral anticoagulation.
Spontaneous intracranial hemorrhage is the most devastating complication of thrombolytic therapy, and in this series, one (<1%) patient experienced a fatal intracerebral hemorrhage. Another patient developed a subdural hematoma after a fall that necessitated surgical evacuation, without neurologic sequelae.
The recorded frequency of symptomatic PE occurring during lysis was low. Although the true prevalence of PE is unknown, only six symptomatic PEs occurred, for a prevalence of 1%. Of those, one was fatal and occurred 15 hours after initiation of thrombolysis.
Because the establishment of the registry was not designed to be a controlled trial, no restrictions, such as duration of symptoms, location of thrombus, history of DVT, or technique of thrombolysis, were imposed on patient enrollment. Therefore, patients with a variety of these features were prospectively enrolled. This may help explain the relatively low overall yield of complete lysis (31%). When the analysis is performed according to subgroups, however, several important observations can be made. For example, in patients with acute iliofemoral DVT and no history of DVT and in whom thrombolysis was performed via the popliteal vein (without a pedal infusion), complete lysis occurred 65% of the time, and the 1-year patency rate was 96%. At the other extreme, complete lysis never occurred in patients with chronic femoral-popliteal DVT. Analysis of groups with particular combinations of features, although the groups were not always large enough for statistical comparison, provided a useful perspective of what can be expected from thrombolysis in different settings, and the results can serve as a guide to patient selection for this potentially effective form of treatment.
In conclusion, catheter-directed thrombolysis can be used to dissolve thrombus safely and effectively from the deep veins in identifiable groups of patients with symptomatic lower limb DVT. The best results can be anticipated in patients with acute symptoms and no history of DVT and who are treated with thrombolysis without systemic infusion. The long-term benefits of this form of therapy are not yet known and cannot conclusively be derived from the results of this study. Thrombolytic therapy has the potential for protecting the patient against chronic venous insufficiency and is related to the achievement and maintenance of patency and the preservation of valve function.
Patency alone was addressed in this initial report. Longer follow-up is needed to evaluate the effect of catheter-directed thrombolysis on venous valvular function. The Venous Registry data should be helpful for designing the protocol of a controlled trial to compare catheter-directed thrombolysis and anticoagulation. Such a controlled trial will be necessary to validate the long-term benefits of catheter-directed thrombolysis and its application for the prevention of postthrombotic syndrome.
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Acknowledgments |
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Footnotes |
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Author contributions: Guarantor of integrity of entire study, M.W.M.; study concepts, M.W.M., M.H.M.; study design, M.W.M., S.H.H., M.H.M., G.R.S.; definition of intellectual content, M.W.M.; literature research, N.L., M.W.M., M.H.M.; clinical studies, see Acknowledgments; data acquisition, S.H.H., M.W.M., G.R.S.; data analysis, M.W.M., M.H.M., J.C., S.H.H.; statistical analysis, M.W.M.; manuscript preparation, M.W.M., M.H.M, S.H.H., G.R.S.; manuscript editing, G.R.S., N.L., S.H.H.; manuscript review, G.R.S., M.H.M., S.H.H.
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) and 79 patients with femoral-popliteal DVT (
). Patients with iliofemoral DVT were more likely to have maintained patency at 1 year than were patients with femoral-popliteal DVT (63.7% vs 46.8%; P < .01). These data are also presented in 
) was 78.9%, whereas the rate in limbs with grade I lysis (