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DVT: Who and When to Treat
Saturday, March 27, 2004 8:00 a.m.-9:30 a.m. Iliofemoral Venous Occlusive Disease: When to Treat and How? (GC) Coordinator/Moderator: Kenneth D. Murphy, MD Objectives: 1. Differentiate the etiologies and risk factors for iliofemoral DVT, and the optimal candidate and time for endovascular intervention. 2. Discuss the limitations of current medical and surgical therapy for iliofemoral DVT. 3. Describe the current thrombolytic agents, delivery techniques, limitations and outcomes in managing iliofemoral DVT. 4. Assess the technical aspects and limitations of current mechanical thrombectomy devices in managing iliofemoral DVT. 5. Compare emerging combination techniques for iliofemoral DVT, including contained pharmacomechanica I lysis and thrombolytic-assisted rheolytic thrombectomy. 8:00 a.m. DVf: Who and When to Treat Albert A. Nfmlcek, Jr, MD Northwestern Memorial Hospital Chicago, II Acute lower extremity deep venous thrombosis (DVT) is a common cause of morbidity and mortality in the United States. Traditional therapy has been directed toward limiting progression of existent deep vein thrombus (which, it turns out, it does rather poorly) and preventing pulmonary emboli and recurrent thrombosis. However, chronic morbidity-the post-phlebitic syndrome, consisting of lower extremity swelling, pain, venous ulceration, and venous claudication-remains a major problem, as anticoagulation alone is rarely associated with significant endogenous lysis of venous thrombus, particularly in cases with large amounts of thrombus. It has been estimated that about two thirds of patients with acute iliofemoral DVT will develop lower extremity pain and edema, and 5% will develop venous ulceration, despite "adequate" (as defined by coagulation parameters) anticoagulation. Furthermore, anticoagulation does nothing to treat underlying lesions which may have predisposed to acute DVT in the first place. This is an important consideration, since it is becomingly increaSingly recognized that cases of iliofemoral DVT are often associated with proximal iliac vein stenosis, the May-Thurner syndrome. It is in this context that more aggressive therapy for iliofemoral DVT has been advocated: thrombolytic therapy and/ or mechanical thrombectomy combined with
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treatment of underlying venous stenoses with angioplasty and/or stent placement. Who to treat with such therapy, and when, remain controversial issues primarily because we do not yet have unassailable data to guide our therapeutic decisions. Ideally, the answers would come in the form of large scale, randomized, prospective studies, in which both short and long term (perhaps 5-10 years or 10ngerO outcomes are compared among treatment arms, all stratified on the basis of recognized potential risk factors (sex, age, body mass index, smoking, duration of symptoms, hypercoagulable states , pre-existing venous stenois, etc) and on the basis of the severity of the initial presentation (from minimally symptomatic patients to those with severe manifestations such as phlegmasia cerulea dolens or massive pulmonary embolism). Clearly such data will not come soon, and we are left with a situation in which legitimate arguments can be made on either side.
Aggressive Therapy for iliofemoral DVf: Who and When? Ideal therapy for acute DVT would eliminate venous thrombus and any conditions predisposing to venous stasis as quickly, thoroughly, and permanently as possible, and do so at low cost and low risk. In this way, not only will pulmonary embolism be prevented (because there is no thrombus to embolize) and acute symptoms and risks be ameliorated, but post-phlebitic syndrome should be minimized by restoring adequate venous flow and preserving normal venous valve function. It seems logical that the use of thrombolytiC therapy might accomplish at least some of these goals. Studies have shown that systemic lytic therapy is significantly more effective-45% vs. 4% in one analysis of the Iiterature-t1lan anticoagulation in achieving complete venous thrombolysis. However, systemic regimens still did not achieve satisfactory venous patency rates, particularly in long-segment and proximal DVT, presumably due to ineffective delivery to occluded segments bypassed by collaterals. Unfortunately, these are the very situations most likely to lead to the post-phlebitic syndrome. Catheter-directed thrombolysis, with direct delivery of concentrated lytic agents to obstructed segments, might be expected to improve response rates, durations, and safety compared to systemic infusion. Application of this concept was first reported by Semba and Dake in 1994; these investigators achieved an encouraging 72% complete lysis rate in 21 patients with iliofemoral DVT. After other small, similarly encouraging reports appeared in the literature, a multi-institutional registry was established in 1995 to allow larger scale evaluation of the results of catheter-directed thrombolysis of symptomatic deep venous thrombosis. The results of the venous registry include data from 63 medical centers at which 473 patients were treated for symptomatic DVT with urokinase. Of these , 287 had complete data sets, with a total of 312 urokinase infu-
sions in 303 limbs. Approximately two thirds of patients in the study group had acute symptomatology, with chronic symptoms in 16% and acute symptoms superimposed upon chronic in 19%. A small percentage of patients (9%) presented with phlegmasia cerulea dolens. The majority (71 %) of patients had iliofemoral DVT, with about a fifth of such cases extending into the inferior vena cava. Catheter access sites included the popliteal vein (42% of cases) , the common femoral vein (28%) and the internal jugular vein (21%); pedal vein infusion was used in conjunction with catheter-directed therapy in 60 cases; in six cases it was the sole site of infusion (essentially representing systemic therapy). Lytic therapy was given for an average of just over two days, with a mean dose of 7.8 million units of urokinase, with most patients monitored in an intensive care unit or step-down unit. Success of thrombolysis was reported relative to the degree of lysis , with Grade 1 lysis less than 50%, Grade 2 lysis greater than 50%, and Grade 3 lysis complete (100%). Overall , Grade 3 lysis was achieved in 31% of cases, Grade 2 lysis in 52% (thus, 83% had lysis of 50% or greate r), and Grade 1 lysis in 17%. Acute symptomatology was associated with a bette r response than chronic, with a 34% vs. 19% Grade III response, respectively. Similarly, patients with no prior history of DVT responded better than those with such a history, with 36% vs. 20% Grade III lysis achieved. The small number of patients receiving exclusively systemic (pedal vein) therapy responded poorly, with greate r than 50% lysis achieved in only o ne of six limbs; additionally, duration of lytic therapy was Significantly longer in these limbs. The longer term results of lysis, as might be antiCipated, depended to a great extent on initial results. Overall, primary patency of treated limbs was 65% at 6 months and 60% at 1 year. However, when there was complete lysis initially, 79% of treated limbs remained patent at one year, compared with 32% of limbs with Grade 1 lysis. Further, when complete lysis was achieved in the setting of acute DVT, a 90% 1 year patency was achieved. After lysis of iliofemoral DVT, stenoses were often discovered in the iliac vein of the involved limb. In 40% of all cases, a metallic stent was placed in the iliac vein to treat such stenoses, and such stents appeared beneficial: 1 year patency of 74% was achieved in cases with iliac vein stent placement, compared to 53% without stent placement. On the other hand, res ults of femoropoplitea l stent placement were poor, with four of five such stents occluding within 1.5 months. Major bleeding complications (necessitating transfusion) occurred in 11.5% of cases; close to 40% occurred at the venous entry site. Fatal complicatio ns occurred twice (0.04%), one related to pulmonary embolism and one the result of intracranial hemorrhage. Symptomatic pulmonalY emboli, including the fatal pulmonary embolism, occurred in six cases 0.3%). Thus , the venous registry wo uld suggest that (a) selective thrombolytic therapy compares favorably with
systemic lytiC therapy based on historical controls; (b) the best candidates for catheter-directed venous thrombolysis are those with acute « 10 days symptoms) iliofemoral DVT, with no prior history of DVT. Precautions relevant to lytiC therapy and anticoagulation in other settings should also apply, with contraindi cations including active internal bleeding, history of major neurologic surgery or cerebrovascu lar accident. What about the longer term outcomes of these patients? Come rota evaluated 98 patients treated with catheter directed thrombolysis or anticoagulation to determine whether (a) cathe ter-directed thrombolysis is associated with improved quality of life compared to standard anticoagulation therapy, and (b) whether the success of thrombolysis is related to long term outcomes. Sixty-eight of these patients came from the aforementio ned venous·registry and were treated at least 6 months previously with catheter-directed thrombolysis, and 30 patients were identified by medical record review and were treated with anticoagulation . Starting with groups initially comparable in terms of pre-DVT quality of life, patients in the thrombolysis group reported better posttreatment physical functioning, less health distress, and fewer postthrombotic symptoms. Further, successful thrombolysis correlated positively with quality of life within the thrombolytiC group. In another study, published in 2000, Schweizer et al evaluated 250 patients with acute lower extremity DVT who were randomized into five treatment groups. All received full heparinization and compression treatmen t. The five groups were divided as foll ows : (i) anti coagulation only, (ij) locoregionallytic therapy with t-PA (20 mg/day) , (iii) locoregional therapy with urokinase (100,000 U/d), (iv) systemic lytiC therapy with streptokinase (300,000 U/d) , and (v) systemic lytiC therapy with urokinase (5,000,000 IU/day). It should be noted, however, that locoregional therapy in this study was defined as infUSio n into the affected leg via a dorsal pedal vein; patients did not receive catheter-directed therapy. In their study , systemic thrombolytic therapy Significa ntly reduced the number of closed vein segments in the involved limb after 12 months compared to conventional therapy. Additionally, patients treated systemically had a significantly decreased occurre nce of post-thrombotic syndrome compared to controls. Interestingly, systemic therapy led to better rates of complete recanalization at one week than locoregional lysis. However, the improvements in outcome related to lytic therapy were achieved at a cost: 12 patients (nine receiving systemic therapy, three local) had major bleeding complications. These complications resulted in early termination of lytic therapy; all were managed conservatively, and there were no deaths. Moreover, nine patients receiving systemic treatment developed clinical signs of pulmonalY emboli, although these symptoms resolved in a short period of time in all nine patients. No symptomatic pulmonary emboli occurred in controls. The authors concluded that systemic thrombolysis is effective in im-
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praving the longer-term outcome of DVT but should be used selectively in limb-threatening thrombotic situations due to the risks for serious complications. Further evidence for improved results of thrombolytic therapy in patients with more acute DVT derives from a study in which the prognostic value of CT was assessed prior to therapy. Roh and colleagues noted that good response to thrombolytic therapy was associated with higher attenuation of thrombus on noncontrast CT, greater distension of veins, and poor demarcation of venous walls, all arguable signs of more recent thrombosis. In this study of 24 patients, recent onset of clinical symptoms was also associated with better outcome. While patients with hypercoagulable states have been included in several of the published studies on DVT thrombolysis, there has been little in the way of comparison of such patients with those unafflicted with such disorders. Cho et al reported 100% technical and clinical success in five patients with protein C and/ or S deficiency treated with catheter directed urokinase thrombolysis. In the previously mentioned study by Schweizer et ai, hypercoagulable states were identified in a large percentage of patients (immobilization 32%, antithrombin defiCiency 16%, familial thrombophilia taking hormonal contraceptives 16%, protein C defiCiency 4%) but there is no stratification of results based on these factors. Conclusion The last decade has seen a great deal of interest in, although more limited performance of, aggressive therapy for lower extremity deep venous thrombosis. While data is slowly accumulating as to the potential benefits of such therapy as compared to standard anticoagulation, current evidence is flawed by lack of large scale randomized prospective studies, stratification on the basis of risk factors and clinical presentation, and long term followup. Thus, we have little prospective data on such questions as whether aggressive therapy improves long-term outcomes of DVT, or even short term outcomes in certain subgroups (e.g. phlegmasia cerulea dolens) at an acceptable balance of risk and benefit, as well as which types of patients are most likely to benefit from such therapy. It is hoped that the encouraging preliminary data will lead to performance of appropriately designed studies.
References 1. Arcasoy SM, Vachani A. Local and systemic thrombolytiC therapy for acute venous thromboembolism. Clin Chest Med 2003; 24:73-91. 2. Bjarnason H, Kruse JR, Asinger DA, et al. Iliofemoral deep venous thrombosis: safety and efficacy outcome during 5 years of catheter-directed thrombolytic therapy. ]VIR 1997; 8:405-418. 3. Cho YP, Jang HJ, Lee DH, et al. Deep venous thrombosis associated with protein C and/or S defiCiency: management with catheter-directed thrombolysiS. Br J Radiology 2003; 76:380-383.
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4. Comerota A], Aldridge Sc. Thrombolytic therapy for acute deep vein thrombosis. Semin Vasc Surg 1992; 5:76-81. 5. Comerota A], Aldridge SC, Cohen G, et al. A strategy of aggressive regional therapy for acute iliofemoral venous thrombosis with contemporary venous thrombectomy or catheter-directed thrombolysis. J Vasc Surg 1994; 20:244-254. 6. Come rota AJ. Quality-of-life improvement using thrombolytic therapy for iliofemoral deep venous thrombosis. Rev Cardiovasc Med 2002; 3 Suppl 2:S60-66. 7. Dake MD, Semba CPo ThrombolytiC therapy in venous occlusive disease. ]VIR 1995; 6:73S-77S. 8. Hirsh], Hoak]. Management of deep vein thrombosis and pulmonary embolism. Circulation 1996; 93: 2212-2245. 9. Johnson BF, Manzo RA, Bergelin RO, Strandness DE, ]r. Relationship between changes in the deep venous system and development of the postthrombotic syndrome after an acute episode of lower limb deep vein thrombosis: a one- to six-year follow-up.] Vasc Surg 1995; 21:307-313. 10. Mewissen MW, Seabrook GR, Meissner MH, et al. Catheter-directed thrombolysis for lower extremity deep vein thrombosis: report of a national multicenter registry. Radiology 1999; 211:39-49. 11. Mewissen MW, Seabrook GB, Haughton SH. Catheter-directed thrombolysis for the treatment of symptomatic lower extremity deep vein thrombosis. Techniques in Intervent Radiol 1998; 1:192-198. i2. Roh B, Park K, Kim E, et al. Prognostic value of CT before thrombolytic therapy in iliofemoral deep venous thrombosis. ]VIR 2002; 13:71-76. 13. Schweizer ], Kirch W, Koch R, et a.. Short- and long-term results after thrombolytiC treatment of deep venous thrombosis. ] Am Coli Cardiol 2000; 36:1336-1343. 14. Semba CP, Dake MD. Iliofemoral deep venous thrombosis: aggressive therapy with catheter-directed thrombolysis . Radiology 1994; 191 :487-496. 15. Semba CP, Dake MD. Catheter-directed thrombolysis for iliofemoral venous thrombosis. Semin Vasc Surg 1996; 9:26-33. 8:15 a.m. Limitations of Medical/Surgical Management of DVI'
Nilesh H. Patel, MD Rush University Medical Center Chicago,IL
Population based studies suggest that there are over 250,000 new cases of acute deep venous thrombosis (DVT) per year in the United States 0, 2). Up to 50% of
P60
treatment of underlying venous stenoses with angioplasty and/or stent placement. Who to treat with such therapy, and when, remain controversial issues primarily because we do not yet have unassailable data to guide our therapeutic decisions. Ideally, the answers would come in the form of large scale, randomized, prospective studies, in which both short and long term (perhaps 5-10 years or 10ngerO outcomes are compared among treatment arms, all stratified on the basis of recognized potential risk factors (sex, age, body mass index, smoking, duration of symptoms, hypercoagulable states , pre-existing venous stenois, etc) and on the basis of the severity of the initial presentation (from minimally symptomatic patients to those with severe manifestations such as phlegmasia cerulea dolens or massive pulmonary embolism). Clearly such data will not come soon, and we are left with a situation in which legitimate arguments can be made on either side.
Aggressive Therapy for iliofemoral DVf: Who and When? Ideal therapy for acute DVT would eliminate venous thrombus and any conditions predisposing to venous stasis as quickly, thoroughly, and permanently as possible, and do so at low cost and low risk. In this way, not only will pulmonary embolism be prevented (because there is no thrombus to embolize) and acute symptoms and risks be ameliorated, but post-phlebitic syndrome should be minimized by restoring adequate venous flow and preserving normal venous valve function. It seems logical that the use of thrombolytiC therapy might accomplish at least some of these goals. Studies have shown that systemic lytic therapy is significantly more effective-45% vs. 4% in one analysis of the Iiterature-t1lan anticoagulation in achieving complete venous thrombolysis. However, systemic regimens still did not achieve satisfactory venous patency rates, particularly in long-segment and proximal DVT, presumably due to ineffective delivery to occluded segments bypassed by collaterals. Unfortunately, these are the very situations most likely to lead to the post-phlebitic syndrome. Catheter-directed thrombolysis, with direct delivery of concentrated lytic agents to obstructed segments, might be expected to improve response rates, durations, and safety compared to systemic infusion. Application of this concept was first reported by Semba and Dake in 1994; these investigators achieved an encouraging 72% complete lysis rate in 21 patients with iliofemoral DVT. After other small, similarly encouraging reports appeared in the literature, a multi-institutional registry was established in 1995 to allow larger scale evaluation of the results of catheter-directed thrombolysis of symptomatic deep venous thrombosis. The results of the venous registry include data from 63 medical centers at which 473 patients were treated for symptomatic DVT with urokinase. Of these , 287 had complete data sets, with a total of 312 urokinase infu-
sions in 303 limbs. Approximately two thirds of patients in the study group had acute symptomatology, with chronic symptoms in 16% and acute symptoms superimposed upon chronic in 19%. A small percentage of patients (9%) presented with phlegmasia cerulea dolens. The majority (71 %) of patients had iliofemoral DVT, with about a fifth of such cases extending into the inferior vena cava. Catheter access sites included the popliteal vein (42% of cases) , the common femoral vein (28%) and the internal jugular vein (21%); pedal vein infusion was used in conjunction with catheter-directed therapy in 60 cases; in six cases it was the sole site of infusion (essentially representing systemic therapy). Lytic therapy was given for an average of just over two days, with a mean dose of 7.8 million units of urokinase, with most patients monitored in an intensive care unit or step-down unit. Success of thrombolysis was reported relative to the degree of lysis , with Grade 1 lysis less than 50%, Grade 2 lysis greater than 50%, and Grade 3 lysis complete (100%). Overall , Grade 3 lysis was achieved in 31% of cases, Grade 2 lysis in 52% (thus, 83% had lysis of 50% or greate r), and Grade 1 lysis in 17%. Acute symptomatology was associated with a bette r response than chronic, with a 34% vs. 19% Grade III response, respectively. Similarly, patients with no prior history of DVT responded better than those with such a history, with 36% vs. 20% Grade III lysis achieved. The small number of patients receiving exclusively systemic (pedal vein) therapy responded poorly, with greate r than 50% lysis achieved in only o ne of six limbs; additionally, duration of lytic therapy was Significantly longer in these limbs. The longer term results of lysis, as might be antiCipated, depended to a great extent on initial results. Overall, primary patency of treated limbs was 65% at 6 months and 60% at 1 year. However, when there was complete lysis initially, 79% of treated limbs remained patent at one year, compared with 32% of limbs with Grade 1 lysis. Further, when complete lysis was achieved in the setting of acute DVT, a 90% 1 year patency was achieved. After lysis of iliofemoral DVT, stenoses were often discovered in the iliac vein of the involved limb. In 40% of all cases, a metallic stent was placed in the iliac vein to treat such stenoses, and such stents appeared beneficial: 1 year patency of 74% was achieved in cases with iliac vein stent placement, compared to 53% without stent placement. On the other hand, res ults of femoropoplitea l stent placement were poor, with four of five such stents occluding within 1.5 months. Major bleeding complications (necessitating transfusion) occurred in 11.5% of cases; close to 40% occurred at the venous entry site. Fatal complicatio ns occurred twice (0.04%), one related to pulmonary embolism and one the result of intracranial hemorrhage. Symptomatic pulmonalY emboli, including the fatal pulmonary embolism, occurred in six cases 0.3%). Thus , the venous registry wo uld suggest that (a) selective thrombolytic therapy compares favorably with
systemic lytiC therapy based on historical controls; (b) the best candidates for catheter-directed venous thrombolysis are those with acute « 10 days symptoms) iliofemoral DVT, with no prior history of DVT. Precautions relevant to lytiC therapy and anticoagulation in other settings should also apply, with contraindi cations including active internal bleeding, history of major neurologic surgery or cerebrovascu lar accident. What about the longer term outcomes of these patients? Come rota evaluated 98 patients treated with catheter directed thrombolysis or anticoagulation to determine whether (a) cathe ter-directed thrombolysis is associated with improved quality of life compared to standard anticoagulation therapy, and (b) whether the success of thrombolysis is related to long term outcomes. Sixty-eight of these patients came from the aforementio ned venous·registry and were treated at least 6 months previously with catheter-directed thrombolysis, and 30 patients were identified by medical record review and were treated with anticoagulation . Starting with groups initially comparable in terms of pre-DVT quality of life, patients in the thrombolysis group reported better posttreatment physical functioning, less health distress, and fewer postthrombotic symptoms. Further, successful thrombolysis correlated positively with quality of life within the thrombolytiC group. In another study, published in 2000, Schweizer et al evaluated 250 patients with acute lower extremity DVT who were randomized into five treatment groups. All received full heparinization and compression treatmen t. The five groups were divided as foll ows : (i) anti coagulation only, (ij) locoregionallytic therapy with t-PA (20 mg/day) , (iii) locoregional therapy with urokinase (100,000 U/d), (iv) systemic lytiC therapy with streptokinase (300,000 U/d) , and (v) systemic lytiC therapy with urokinase (5,000,000 IU/day). It should be noted, however, that locoregional therapy in this study was defined as infUSio n into the affected leg via a dorsal pedal vein; patients did not receive catheter-directed therapy. In their study , systemic thrombolytic therapy Significa ntly reduced the number of closed vein segments in the involved limb after 12 months compared to conventional therapy. Additionally, patients treated systemically had a significantly decreased occurre nce of post-thrombotic syndrome compared to controls. Interestingly, systemic therapy led to better rates of complete recanalization at one week than locoregional lysis. However, the improvements in outcome related to lytic therapy were achieved at a cost: 12 patients (nine receiving systemic therapy, three local) had major bleeding complications. These complications resulted in early termination of lytic therapy; all were managed conservatively, and there were no deaths. Moreover, nine patients receiving systemic treatment developed clinical signs of pulmonalY emboli, although these symptoms resolved in a short period of time in all nine patients. No symptomatic pulmonary emboli occurred in controls. The authors concluded that systemic thrombolysis is effective in im-
P61
praving the longer-term outcome of DVT but should be used selectively in limb-threatening thrombotic situations due to the risks for serious complications. Further evidence for improved results of thrombolytic therapy in patients with more acute DVT derives from a study in which the prognostic value of CT was assessed prior to therapy. Roh and colleagues noted that good response to thrombolytic therapy was associated with higher attenuation of thrombus on noncontrast CT, greater distension of veins, and poor demarcation of venous walls, all arguable signs of more recent thrombosis. In this study of 24 patients, recent onset of clinical symptoms was also associated with better outcome. While patients with hypercoagulable states have been included in several of the published studies on DVT thrombolysis, there has been little in the way of comparison of such patients with those unafflicted with such disorders. Cho et al reported 100% technical and clinical success in five patients with protein C and/ or S deficiency treated with catheter directed urokinase thrombolysis. In the previously mentioned study by Schweizer et ai, hypercoagulable states were identified in a large percentage of patients (immobilization 32%, antithrombin defiCiency 16%, familial thrombophilia taking hormonal contraceptives 16%, protein C defiCiency 4%) but there is no stratification of results based on these factors. Conclusion The last decade has seen a great deal of interest in, although more limited performance of, aggressive therapy for lower extremity deep venous thrombosis. While data is slowly accumulating as to the potential benefits of such therapy as compared to standard anticoagulation, current evidence is flawed by lack of large scale randomized prospective studies, stratification on the basis of risk factors and clinical presentation, and long term followup. Thus, we have little prospective data on such questions as whether aggressive therapy improves long-term outcomes of DVT, or even short term outcomes in certain subgroups (e.g. phlegmasia cerulea dolens) at an acceptable balance of risk and benefit, as well as which types of patients are most likely to benefit from such therapy. It is hoped that the encouraging preliminary data will lead to performance of appropriately designed studies.
References 1. Arcasoy SM, Vachani A. Local and systemic thrombolytiC therapy for acute venous thromboembolism. Clin Chest Med 2003; 24:73-91. 2. Bjarnason H, Kruse JR, Asinger DA, et al. Iliofemoral deep venous thrombosis: safety and efficacy outcome during 5 years of catheter-directed thrombolytic therapy. ]VIR 1997; 8:405-418. 3. Cho YP, Jang HJ, Lee DH, et al. Deep venous thrombosis associated with protein C and/or S defiCiency: management with catheter-directed thrombolysiS. Br J Radiology 2003; 76:380-383.
P62
4. Comerota A], Aldridge Sc. Thrombolytic therapy for acute deep vein thrombosis. Semin Vasc Surg 1992; 5:76-81. 5. Comerota A], Aldridge SC, Cohen G, et al. A strategy of aggressive regional therapy for acute iliofemoral venous thrombosis with contemporary venous thrombectomy or catheter-directed thrombolysis. J Vasc Surg 1994; 20:244-254. 6. Come rota AJ. Quality-of-life improvement using thrombolytic therapy for iliofemoral deep venous thrombosis. Rev Cardiovasc Med 2002; 3 Suppl 2:S60-66. 7. Dake MD, Semba CPo ThrombolytiC therapy in venous occlusive disease. ]VIR 1995; 6:73S-77S. 8. Hirsh], Hoak]. Management of deep vein thrombosis and pulmonary embolism. Circulation 1996; 93: 2212-2245. 9. Johnson BF, Manzo RA, Bergelin RO, Strandness DE, ]r. Relationship between changes in the deep venous system and development of the postthrombotic syndrome after an acute episode of lower limb deep vein thrombosis: a one- to six-year follow-up.] Vasc Surg 1995; 21:307-313. 10. Mewissen MW, Seabrook GR, Meissner MH, et al. Catheter-directed thrombolysis for lower extremity deep vein thrombosis: report of a national multicenter registry. Radiology 1999; 211:39-49. 11. Mewissen MW, Seabrook GB, Haughton SH. Catheter-directed thrombolysis for the treatment of symptomatic lower extremity deep vein thrombosis. Techniques in Intervent Radiol 1998; 1:192-198. i2. Roh B, Park K, Kim E, et al. Prognostic value of CT before thrombolytic therapy in iliofemoral deep venous thrombosis. ]VIR 2002; 13:71-76. 13. Schweizer ], Kirch W, Koch R, et a.. Short- and long-term results after thrombolytiC treatment of deep venous thrombosis. ] Am Coli Cardiol 2000; 36:1336-1343. 14. Semba CP, Dake MD. Iliofemoral deep venous thrombosis: aggressive therapy with catheter-directed thrombolysis . Radiology 1994; 191 :487-496. 15. Semba CP, Dake MD. Catheter-directed thrombolysis for iliofemoral venous thrombosis. Semin Vasc Surg 1996; 9:26-33. 8:15 a.m. Limitations of Medical/Surgical Management of DVI'
Nilesh H. Patel, MD Rush University Medical Center Chicago,IL
Population based studies suggest that there are over 250,000 new cases of acute deep venous thrombosis (DVT) per year in the United States 0, 2). Up to 50% of