Transcatheter regional urokinase therapy in the management of inferior vena cava thrombosis

Endovascular Strategy for Inferior Vena Cava Thrombosis Secondary to Deep Venous Thrombosis of the Lower Extremities: Early Experience From Two Centres

PURPOSE

To evaluate the safety, feasibility and technical aspects of endovascular treatments for inferior vena cava (IVC) thrombosis secondary to deep venous thrombosis of the lower extremities.

MATERIALS AND METHODS

A retrospective study of patients from two centres who received endovascular treatment for IVC thrombosis from January 2015 to December 2020. Under the protection of the IVC filter, all lesions were treated with manual aspiration thrombectomy (MAT) followed by catheter-directed thrombolysis (CDT). Technical aspects, complications, IVC patency, Venous Clinical Severity Score (VCSS) score and Villalta score were recorded during the follow-up observation.

RESULTS

Endovascular procedures including MAT and CDT were performed successfully in 36 patients (97.3%). The average duration of the endovascular procedure was 71 minutes (range: 35-152 min). To protect against fatal pulmonary artery embolism, 33 filters (91.7%) were deployed in the inferior renal IVC, while three patients (8.3%) received filter implantation in the retrohepatic IVC. No severe complications occurred during the procedure. In the follow-up observations, the cumulative primary and secondary patency rates in IVC were 95% and 100%, respectively. The patency rates for the iliac vein were as follows: a primary patency rate of 77% and a secondary patency rate of 85%. The average VCSS score was 5.9 ± 2.6, and the Villalta score was 3.9 ± 2.2. The rate of post thrombotic syndrome is 22% in our study as assessed by the villalta score (Villalta score>4).

CONCLUSIONS

Endovascular treatment for IVC thrombosis secondary to DVT of the lower extremities is feasible, safe, and effective. This strategy alleviates venous insufficiency and results in a high patency rate in IVC.

Outcomes of Pharmacomechanical Catheter-directed Thrombolysis for Acute and Subacute Inferior Vena Cava Thrombosis: A Retrospective Evaluation in a Single Institution

OBJECTIVE/BACKGROUND

The objective was to assess the mid-term results of pharmacomechanical catheter-directed thrombolysis (PCDT) for symptomatic acute and subacute inferior vena cava (IVC) thrombosis; the risk factors of early thrombosis recurrence and iliocaval patency were also evaluated.

METHODS

From January 2010 to December 2015, 54 patients (33 men; mean age 47.1 years) with symptomatic acute and subacute IVC thrombosis were treated with PCDT. Primary technical success (clot lysis ≥ 50% after PCDT), stent-assisted technical success (residual stenosis < 30% after stenting), clinical success (freedom from thrombosis recurrence within 30 days), complications, frequency of post-thrombotic syndrome (PTS; Villalta score ≥ 5), and iliocaval patency were recorded at follow-up evaluation. A multivariate regression model was used to determine predictors of early thrombosis reoccurrence and iliocaval patency.

RESULTS

The primary technical success and the stent-assisted technical success were 63% (n = 34/54) and 100% (n = 54/54) respectively. There were 11 patients (20%) with immediate recurrent thrombosis requiring repeat PCDT. Minor bleeding complications occurred in seven patients, and one patient with major bleeding needed a blood transfusion. The occurrence of PTS at a mean of 26 months (range 1-60 months) was 13% (7/54). The 3-year primary and secondary iliocaval patency was 63% and 81%, respectively. On multivariate analysis, active malignancy was predictive of immediate IVC thrombosis recurrence (hazard ratio [HR] 5.8, 95% confidence interval [CI] 1.7-19.8; p = .01), whereas the pre-existing filter played a protective role against iliocaval re-occlusion (HR 0.3, 95% CI 0.1-0.8; p = .01).

CONCLUSIONS

PCDT is safe and effective in managing symptomatic acute and subacute IVC thrombosis. Active malignancy is predictor of thrombosis re-occurrence, whereas the presence of a filter is associated with a higher rate of iliocaval patency at mid-term follow-up.

Retrievable Inferior Vena Cava Filters in Trauma Patients: Prevalence and Management of Thrombus Within the Filter

OBJECTIVE

The incidence of thrombus was investigated within retrievable filters placed in trauma patients with confirmed DVT at the time of retrieval and the optimal treatment for this clinical scenario was assessed. A technique called "filter retrieval with manual negative pressure aspiration thrombectomy" for management of filter thrombus was introduced and assessed.

METHODS

The retrievable filters referred for retrieval between January 2008 and December 2015 were retrospectively reviewed to determine the incidence of filter thrombus on a pre-retrieval cavogram. The clinical outcomes of different managements for thrombus within filters were recorded and analyzed.

RESULTS

During the study 764 patients having Aegisy Filters implanted were referred for filter removal, from which 236 cases (134 male patients, mean age 50.2 years) of thrombus within the filter were observed on initial pre-retrieval IVC venogram 12-39 days after insertion (average 16.9 days). The incidence of infra-filter thrombus was 30.9%, and complete occlusion of the filter bearing IVC was seen in 2.4% (18) of cases. Retrieval was attempted in all 121 cases with small clots using a regular snare and sheath technique, and was successful in 120. A total of 116 cases with massive thrombus and IVC occlusion by thrombus were treated by CDT and/or the new retrieval technique. Overall, 213 cases (90.3%) of thrombus in the filter were removed successfully without PE.

CONCLUSIONS

A small thrombus within the filter can be safely removed without additional management. CDT for reduction of the clot burden in filters was effective and safe. Filter retrieval with manual negative pressure aspiration thrombectomy seemed reasonable and valuable for management of massive thrombus within filters in some patients. Full assessment of the value and safety of this technique requires additional studies.

Impact of inferior vena cava thrombus extension on thrombolysis for acute iliofemoral thrombosis

BACKGROUND

Inferior vena cava (IVC) thrombosis may occur in patients with iliofemoral deep venous thrombosis (DVT), and its impact on thrombolysis outcomes is poorly defined. This study compared outcomes of patients undergoing thrombolysis for acute iliofemoral DVT with and without IVC involvement.

METHODS

Patients who underwent thrombolysis for iliofemoral DVT between May 2007 and March 2014 were identified from a prospectively maintained database and divided into two groups: those with IVC involvement and those without. End points were technical and clinical success (≥50% lysis or freedom from 30-day DVT recurrence), long-term DVT recurrence, and post-thrombotic syndrome (PTS; Villalta score ≥5). Multivariate regression models were used to determine predictors of anatomic and clinical failures.

RESULTS

There were 102 patients (127 limbs) treated with various combinations of catheter-directed or pharmacomechanical thrombolysis. In 46 patients, thrombus extended into the IVC (54.3% extended up to the renal veins; 87% had ≥50% luminal reduction; 50% occurred in association with an indwelling thrombosed IVC filter). The caval group had fewer women and more previous DVTs but otherwise was similar to the noncaval group. Pharmacomechanical thrombolysis was used more frequently in the caval thrombus group (97.8% vs 82.1%; P = .011), and iliac vein stenting was used more often in the noncaval group (41.3% vs 62.5%; P = .033). Clinical success was similar between the two groups (88.7% for caval vs 89.3% for noncaval; P = .921). All failures in the caval group occurred in patients with an indwelling thrombosed IVC filter. Primary patency at 2 years for the caval and noncaval groups was 76.7% and 78.0%, respectively (P = .787). Valve reflux and PTS at 2 years were higher in the noncaval group (50.8% and 34.3% vs 23.3% and 11.5% in the caval group; P = .013 and P = .035). On multivariate analysis, incomplete lysis was predictive of recurrence (hazard ratio [HR], 22.7; P < .001) and PTS (HR, 5.59; P = .010), whereas caval involvement (HR, 0.22; P = .005) was protective from PTS.

CONCLUSIONS

IVC thrombosis does not have an impact on the technical success of thrombolysis in patients with iliofemoral DVT; the presence of a thrombosed IVC filter, though, may make failure more likely. Caval thrombosis may not affect primary patency but is associated with a lower incidence of PTS after successful lysis.

Inferior Vena Cava Filter-Related Thrombus/Deep Vein Thrombosis: Data and Management

Recurrent deep venous thrombosis and inferior vena cava (IVC) thrombosis are well-described complications following IVC filter placement. IVC thrombosis ranges in severity of clinical presentation, but can lead to significant morbidity and mortality with incidence rates depending on patient population and type of filter used. Endovascular therapies such as catheter-directed thrombolysis, mechanical thrombectomy, balloon venoplasty, and stenting are safe and effective in restoration of venous patency.

Endovascular intervention for deep venous thrombosis in patients with inferior vena cava filters

Patients with inferior vena cava (IVC) filter-associated deep venous thrombosis (DVT) are a challenging subset of patients for endovascular intervention. Given the lack of available data pertaining to this clinical scenario, the purpose of this study was to evaluate the authors' experience with the use of endovascular treatment for DVT in patients with IVC filters. Primary aims included assessing the technical and clinical success, complications, and clinical patency in these patients. This was a retrospective single-center review of adult patients with IVC filters undergoing endovascular treatment of DVT between 1/2005 and 4/2014. Patient electronic medical records were reviewed for demographic data, anticoagulation status, symptoms, symptomatic extremities, extent of thrombosis, therapies received, technical and clinical success, and complications. Query yielded 82 patients (mean 53 years, range 18-96; 66% male), all of whom were included in our analysis. The majority of patients presented with lower extremity pain and swelling, with extensive clot burden despite the use of anticoagulant medication. Treatment elements utilized included pharmacologic lysis in 92%, mechanical thrombectomy in 77%, angioplasty in 63% and stent placement in 50% of patients. Interventions were technically successful in restoring flow in 87% of patients, and clinically successful in improving presenting symptoms in 79% of patients. By SIR criteria, 24% of patients experienced complications (categorized as 10% minor and 14% major). There were two deaths from intracranial hemorrhage. The probability of thrombosis-free survival at 1, 3, 6, 9 and 12 months was 0.85 (CI 0.74-0.93), 0.81 (CI 0.69-0.89), 0.74 (CI 0.62-0.83), 0.70 (CI 0.57-0.8) and 0.70 (CI 0.57-0.8), respectively. Endovascular interventions are usually effective in relieving symptoms in patients with DVT and pre-existing IVC filters. However, these outcomes are achieved with significant complication rates that may exceed those observed when endovascular therapy is provided for other DVT populations.

Transcatheter thrombolytic therapy for symptomatic thrombo-occlusion of inferior vena cava filter

Thrombus within an inferior vena cava (IVC) filter reduces filter patency and venous return from the lower extremities, and may progress to complete IVC occlusion. The clinical experiences and outcomes of transcatheter thrombolytic therapy for symptomatic IVC thrombosis following filter implantation have not been widely reported. The aim of the current study was to evaluate the efficiency and safety of trans-catheter thrombolysis for the treatment of symptomatic IVC thrombosis in patients with implanted IVC filters. Transcatheter thrombolysis was used to treat 5 patients with thrombosis of the filter-bearing IVC causing symptoms in 10 limbs from October 2005 to September 2010. The patients were implanted with a second IVC filter through the right internal jugular vein, followed by recanalization of the occluded IVC and intravenous transcatheter thrombolysis. The IVC filters were retrieved through the femoral or right internal jugular vein after the thrombus had dissolved. Technical and clinical outcome, complications and postoperative pulmonary embolism were monitored. A total of 5 filters were implanted and 6 filters were retrieved later. Technically and clinically successful recanalization and thrombolysis were achieved in 5 of 5 patients and 10 of 10 symptomatic limbs. The median thrombolysis period was 13 days (range, 8-14 days). The median dwell time for the filters that were removed was 50.5 days (range, 14-73 days). No major bleeding occurred during the current study. During clinical follow-up, no clinically detectable pulmonary embolism was observed. Endovascular recanalization and transcatheter thrombolysis of IVC thrombosis are efficient, feasible and safe in the presence of an IVC filter.

Management of the thrombosed filter-bearing inferior vena cava

Inferior vena cava (IVC) filter thrombosis is a complex problem. Thrombus within an IVC filter may range from an asymptomatic small thrombus to critical IVC occlusion that affects both lower extremities. The published experience of IVC thrombosis management in relation to filters is either anecdotal or limited to a small group of patients; however, endovascular treatment methods appear to be safe and effective in patients with IVC thrombosis. This review focuses on filter-related IVC thrombosis and its endovascular management.

Vena cava interruption

Anticoagulation has been proven to be effective in preventing and treating deep vein thrombosis and pulmonary embolus. However, many critically ill patients are unable to receive anticoagulation or suffer recurrent venous thromboembolism despite adequate treatment. This article examines the use of vena cava filters in the critically ill. Indications for, techniques, and complications of vena cava filter insertion are reviewed. The importance of vena cava filters with the option to be retrieved and bedside insertion in the intensive care unit is emphasized.

Local thrombolysis: a newer approach to treating inflammatory bowel disease-related thromboembolism

GOALS

To review the experience with a relatively novel treatment, local thrombolysis, in patients with inflammatory bowel disease (IBD)-related thromboembolism (TE).

BACKGROUND

TE is an extraintestinal complication of IBD for which there are no clear treatment guidelines. Systemic treatment with anticoagulants or thrombolytics often raises fear of hemorrhagic complications, particularly hematochezia.

STUDY

Cases of IBD-related and non-IBD-related TE treated with local thrombolysis were searched for in PubMed, reviewed, and grouped into anatomic areas. Outcomes in each anatomic area were compared between IBD and non-IBD patients. Due to the small number of IBD-related TE cases, a descriptive, not statistical, analysis was performed.

RESULTS

There were 17 cases of IBD-related TE treated with local thrombolysis grouped as follows: 7 of cerebral venous thrombosis, 3 of lower extremity arterial TE, 1 of deep vein thrombosis, 1 of upper extremity deep vein thrombosis, 3 of abdominal vein thrombosis, and 2 of inferior vena cava TE. Mean age was 32 (range, 14 to 50) years, and 13 of 17 patients were female. Twelve had ulcerative colitis, 3 had Crohn's disease, and 1 was indeterminate. Four of the 7 patients with active IBD had pretreatment hematochezia, 2 of whom had worsening of hematochezia secondary to treatment. The rates of radiologic resolution, clinical resolution, and hemorrhagic complications in the IBD patients were favorable in all the anatomic areas and were very similar to non-IBD patients.

CONCLUSIONS

Local thrombolysis may be considered a viable therapeutic option for IBD-related TE. As more cases of local thrombolysis for IBD-related TE accumulate, further recommendations can be made as to the indications for its use.

Safety of catheter-directed thrombolysis for deep venous thrombosis in cancer patients

BACKGROUND

The current study was conducted to demonstrate that catheter-directed thrombolysis for upper and lower extremity deep vein thrombosis is equally safe in patients with and without cancer.

METHODS

A retrospective cohort of consecutive patients with acute iliofemoral or brachiosubclavian deep vein thrombosis treated with catheter-directed thrombolysis was identified. Demographic characteristics and clinical outcomes were compared between patients with cancer and without cancer.

RESULTS

Catheter-directed thrombolysis was used to treat 202 limbs in 178 patients (75 limbs in 61 cancer patients and 127 limbs in 117 patients without cancer). The mean treatment duration for patients with cancer (29.7 +/- 21.2 hours) and without cancer (28.8 +/- 22.2 hours) was similar (P = .7774). Catheter-directed thrombolysis achieved grade III clot lysis in a similar proportion of cancer patients (50 of 75 limbs, 66.7%) and patients without cancer (82 of 127 limbs, 64.6%; P = .7619). Grade II clot lysis also was achieved in equal numbers of patients with (20 of 75 limbs, 26.7%) and without cancer (34 of 127 limbs, 26.8%; P = .9872). Three cancer patients (4.9%) and four noncancer patients (3.4%) experienced major bleeding during catheter-directed thrombolysis (P = .6924). Pulmonary embolism occurred in 1.6% (1 of 61) of cancer patients and in 1.7% (2 of 117) of patients without cancer (P = .9999) during catheter-directed thrombolysis. Patients aged > or =70 years had an increased risk of major bleeding.

CONCLUSION

Percutaneous catheter-directed thrombolysis is equally safe for patients with and without cancer who have acute symptomatic deep vein thrombosis.

Transpopliteal removal of an OptEase inferior vena cava filter after treatment of symptomatic filter thrombosis

PURPOSE

To describe a case of transpopliteal retrieval of an inferior vena cava (IVC) filter.

CASE REPORT

A paraplegic patient had an IVC filter placed for deep venous thrombosis (DVT) after anticoagulant therapy was stopped. Two weeks later, he developed massive scrotal and bilateral lower extremity swelling due to iliocaval thrombosis, which was treated by power pulse-spray thrombectomy and catheter-directed thrombolytic infusion via bilateral popliteal approaches. Following successful thrombus removal, the filter was uniquely retrieved via the right popliteal access; the patient was discharged on warfarin anticoagulation.

CONCLUSION

Transpopliteal IVC filter retrieval is feasible and may be a useful alternative technique in selected instances.

Percutaneous Venous Thrombectomy Using the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) with Temporary Caval Filtration: In Vitro Investigations

PURPOSE

To evaluate the size and quantity of downstream emboli after thrombectomy using the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) with or without temporary filtration for extensive iliofemoral and iliocaval thrombi in an in vitro flow model.

METHODS

Iliocaval thrombi were simulated by clotted bovine blood in a flow model (semilucent silicone tubings, diameter 12-16 mm). Five experimental set-ups were performed 10 times each; thrombus particles and distribution were measured in the effluent. First, after retrograde insertion, mechanical thrombectomy was performed using the PTD alone. Then a modified self-expanding tulip-shaped temporary vena cava stent filter was inserted additionally at the beginning of each declotting procedure and removed immediately after the intervention without any manipulation within or at the filter itself. In a third step, the filter was filled with thrombus only. Here, two experiments were performed: Careful closure within the flow circuit without any additional fragmentation procedure and running the PTD within the filter lumen, respectively. In the final set-up, mechanical thrombectomy was performed within the thrombus-filled tubing as well as in the filter lumen. The latter was closed at the end of the procedure and both devices were removed from the flow circuit.

RESULTS

Running the PTD in the flow circuit without filter protection led to a fragmentation of 67.9% (+/-7.14%) of the clot into particles < or =500 microm; restoration of flow was established in all cases. Additional placement of the filter safely allowed maceration of 82.9% (+/-5.59%) of the thrombus. Controlled closure of the thrombus-filled filter within the flow circuit without additional mechanical treatment broke up 75.2% (+/-10.49%), while additional mechanical thrombectomy by running the PTD within the occluded filter led to dissolution of 90.4% (+/-3.99%) of the initial clot. In the final set-up, an overall fragmentation rate of 99.6% (+/-0.44%) was achieved.

CONCLUSIONS

The combined use of the Arrow-Trerotola PTD and a temporary vena cava stent filter proved to be effective for even large clot removal in this experimental set-up.

Acute appendicitis-like symptoms as initial presentation of ovarian vein thrombosis

Postpartum ovarian vein thrombosis is a rare condition, with an incidence rate being 1/600 deliveries. It most often arises in the right ovarian vein. A 33-year-old patient who had had normal vaginal delivery presented with fever, pain in the right iliac fossa, and leukocytosis on the sixth day after delivery. An antibiotic course was instituted but 3 days later symptoms reappeared. Diagnosis of acute appendicitis was made. At surgery through a McBurney incision, a woody tumoration consistent with ovarian vein thrombosis was found. Anticoagulation therapy with heparin and antibiotics were instituted. Phlebography and color Doppler sonography confirmed the presence of thrombosis of both the common femoral iliac and inferior vena cava. Fribrolysis with urokinase was performed. The patient has remained stable and symptom-free over a 4-year follow-up. Ovarian vein thrombosis typically presents with symptoms suggestive of acute appendicitis, as was the case in our patient. Color Doppler sonography is the favored diagnostic procedure, with CT being a supplementary tool. Surgery is not necessary and treatment consists of anticoagulants and antibiotics. Even though postpartum ovarian vein thrombosis is rare, early recognition of the condition is of paramount importance to institute the adequate treatment and avoid potential serious sequelae.

Complications of Inferior Vena Cava Filters

Inferior vena cava (IVC) filters offer a safe and effective means of preventing pulmonary embolus and have reduced complications when compared to earlier techniques of caval interruption. However, despite continued improvement in filters and insertion methods, complications still occur. Pneumothorax, hemorrhage, and vessel injury may result while obtaining vascular access. Filter misplacement, excessive tilt, and vascular injury have been reported with insertion, but preinsertion cavography is helpful in preventing these insertion-related complications. Attention to detail, proper use of guidewires, and preinsertion imaging are vital in preventing insertion-related complications as well. Long-term complications occur in a minority of patients and include recurrent pulmonary embolus, caval occlusion, and filter migration. Overall, the benefits of preventing pulmonary embolism far exceed the risks related to filter placement in properly selected patients.

Endovascular recanalization of the thrombosed filter-bearing inferior vena cava

PURPOSE

To evaluate the authors' preliminary experience with use of endovascular methods to treat inferior vena cava (IVC) thrombosis in patients with IVC filters.

MATERIALS AND METHODS

Catheter-directed thrombolysis, balloon maceration, mechanical thrombectomy, and stent placement were used to treat 10 patients with thrombosis of filter-bearing IVCs causing symptoms in 18 limbs. Procedural challenges, technical and clinical success, complications, postprocedural filter status, and postprocedural pulmonary embolism (PE) prophylaxis were monitored.

RESULTS

Technical and clinical success were achieved in 15 of 18 (83%) and 14 of 18 symptomatic limbs (78%), respectively. Major bleeding (muscular hematoma) occurred in one patient (10%). Postprocedural PE prophylaxis included anticoagulation (n = 8) and placement of a new filter into a newly placed Wallstent (n = 1). During clinical follow-up, no clinically detectable PE was observed. Data pertaining to late limb status were available at a median of 19 months (range 1-46 months) follow-up in seven patients: three patients were asymptomatic, two patients had ambulatory edema only, one patient had constant mild edema, and one patient had constant severe edema. Postprocedural filter stability was radiographically documented at a median of 255 days (range, 4-1021 d) of follow-up.

CONCLUSION

Endovascular recanalization of the occluded IVC is feasible even in the presence of an IVC filter.

Endovascular management of venous thrombotic and occlusive diseases of the lower extremities

Acute complications of deep vein thrombosis (DVT) of the lower extremities include pulmonary embolism and venous ischemia. Delayed complications include a spectrum of debilitating symptoms referred to as postthrombotic syndrome (PST). Anticoagulation therapy is recognized as the mainstay of therapy in acute DVT. However, there are few data to suggest any major beneficial effect on PTS, which is thought to be mediated by valve damage and/or occlusive chronic thrombus and venous scarring. Endovascular catheter-directed thrombolysis techniques with pharmacologic thrombolytic agents, used alone or in combination with mechanical thrombectomy devices, have been proven highly effective in clearing acute DVT, which may allow the preservation of venous valve function and prevention of subsequent venous occlusive disease. Definitive management of underlying anatomic occlusive abnormalities can also be undertaken.

Early results of thrombolysis vs anticoagulation in iliofemoral venous thrombosis. A randomised clinical trial

OBJECTIVE

catheter directed thrombolysis has been advocated for complete and rapid dissolution of iliofemoral deep venous thrombosis (DVT). The aim of our study is to compare, in a randomised trial, local thrombolysis and anticoagulation with anticoagulation alone in patients with iliofemoral DVT.

METHODS

a consecutive series of 35 eligible patients, were randomised to either catheter directed thrombolysis followed by anticoagulation or to anticoagulation alone. Clot lysis and deep venous reflux were assessed with ultrasound duplex and plethysmography after 6 months.

RESULTS

complete data were available in the 18 and 17 patients randomised to thrombolysis and anticoagulation, respectively. At 6 months, patency rate was better in cases treated with thrombolysis [13/18 (72%) vs 2/17 (12%), p < 0.001]. Venous reflux was higher in-patients treated with anticoagulant [7 patients (41%) vs 2 (11%), p = 0.04].

CONCLUSION

in the short-term patients treated with catheter directed thrombolysis obtained better patency and competence than those treated with standard anticoagulation.

Percutaneous venous thrombectomy with the use of a balloon sheath: first in vitro investigations of a new low-tech concept

RATIONALE AND OBJECTIVES

To test mechanical thrombectomy of extensive iliofemoral and iliocaval thrombi in an in vitro flow model with the use of 12F and 18F balloon sheaths.

METHODS

Newly developed 12F and 18F sheaths were evaluated in four vessel models (simulation of femoral, iliofemoral, iliocaval, and caval thrombi by clotted bovine blood in a flow model). After retrograde insertion of the sheath and blocking of the vessel proximal to the thrombus by inflating the balloon, mechanical fragmentation was performed coaxially through the sheath lumen by using a 7F pigtail rotation device. With an occlusion balloon catheter, residual thrombi were withdrawn to the orifice of the sheath and aspirated. Twelve silicone tubes occluded by thrombi were recanalized in each setting. In the latex model, seven recanalizations were performed.

RESULTS

All clots were removed completely within a treatment duration of 2 to 14 minutes. Fluid loss during the procedure was 29.6 to 129.3 mL for the femoral flow model, 61.9 to 137.2 mL for the iliofemoral model, 74.5 to 163.4 mL for the iliocaval model, and 102.7 to 236.7 mL for the caval model. No fragments were washed downstream. In four settings, small residual thrombi were attached to the balloon after deflation of the sheath.

CONCLUSIONS

Clot amounts up to 171 g were removed quickly and completely by using these large-caliber balloon sheaths. Fluid loss from aspiration was negligible. Balloon occlusion prevented embolization of thrombus fragments proximal to the sheath. Further studies are needed to prove the efficacy of this technique in vivo.

The anatomy of deep venous thrombosis of the lower extremity

BACKGROUND

The diagnosis, treatment, and long-term sequelae of lower extremity deep venous thrombosis (DVT) depend on the anatomic location and extent of the process, yet a lack of such fundamental knowledge has limited the development of effective protocols for managing patients with DVT.

METHODS

Venograms with evidence of acute DVT were evaluated, and the extent of the thrombotic process was recorded and correlated with the clinical presentation. Thrombi were classified according to the venous segments involved and to the thrombus' isolation to one segment or multiple segments. The left-to-right ratio of the DVT was assessed for various etiologic subgroups.

RESULTS

Among 2762 venograms performed in 2541 patients over a 10-year period, there were 885 cases (34.8%) of DVT documented. Of these cases, 344 cases (39%) were idiopathic, 307 cases (35%) were postoperative, 84 cases (10%) occurred in the setting of malignancy, and 70 cases (8%) occurred as the result of trauma. Distal thrombi were more common than proximal thrombi, with calf involvement in 734 patients (83%), femoropopliteal involvement in 470 patients (53%), and iliac involvement in 75 patients (9%). The most common site of thrombus was the peroneal vein, which was involved in 595 patients (67%). The ratio of left-to-right-sided DVT was 1.32:1 overall but was greater for proximal thrombi, with a ratio of 2.4:1 for iliac DVT versus 1.3:1 for infrainguinal DVT. The preponderance of left-sided DVT appeared to be related to the high-frequency, left common iliac vein involvement; the left-to-right ratio was much closer to equality (1.09:1) for isolated infrainguinal DVT. The anatomic configuration of the DVT was correlated with the etiologic subgroup; postoperative DVTs were more often distal, whereas DVT developing in the setting of malignancy was more frequently proximal and often right sided. Proximal, left-sided DVTs were common in the idiopathic subgroup, presumably as a result of undiagnosed left iliac vein webs.

CONCLUSIONS

The frequency of distal vein involvement greatly exceeds that of proximal involvement in patients with DVTs. Proximal DVTs are more frequently left sided, whereas distal DVTs occur with a more equal left-to-right distribution. The anatomic extent of DVTs appears to depend on the etiology of the process. These observations may shed light on the pathophysiology of venous thrombosis. The findings are of value in planning therapeutic interventions directed at venous recanalization.