Pharmacomechanical Thrombectomy of Acute Deep Vein Thrombosis with the Trellis-8 Isolated Thrombolysis Catheter

Imaging to intervention: Thoracic outlet syndrome

Thoracic outlet syndrome (TOS) is a clinical disorder resulting from compression of the neurovascular bundle of the lower neck and upper chest. TOS can be categorized into neurogenic, venous, and arterial subtypes which result from anatomical compression of the brachial plexus, subclavian vein, and subclavian artery, respectively. This can lead to neurogenic pain as well as vascular injury with thrombosis and thromboembolism. Interventional and diagnostic radiologists play a critical role in the imaging diagnosis and treatment of vascular TOS. Prompt imaging and endovascular management with surgical collaboration has been shown to provide the most successful and long-lasting clinical outcomes, from vessel patency to symptom relief. In this article, we review the anatomy and clinical presentations of TOS as well as the initial imaging modalities used for diagnosis. Furthermore, we detail the role of the diagnostic and interventional radiologist in the management of TOS, including pre-procedure and endovascular interventions, along with medical and surgical treatments. PRECIS: Diagnostic and Interventional Radiologists play a key role in diagnosis and management of vascular thoracic outlet syndromes and are critical for timely and successful outcomes.

Endovascular Therapy for the Management of Acute Ilio-femoral Deep Vein Thrombosis

Ilio-femoral deep vein thrombosis (DVT) has a high rate of long-term morbidity in the form of the postthrombotic syndrome (PTS). Therefore, management of acute thrombosis should not only focus on the prevention of acute complications such as propagation or embolisation of the initial clot but also on preventing recurrent thrombosis and PTS. Contemporary catheter-based treatments of deep vein thrombosis have proven to be safe and effective in selected patients. Current guidelines recommend medical therapy with anticoagulation alone for all but the most severe, limb-threatening thrombosis. They additionally allow for consideration of endovascular catheter-based treatment in selected patients with acute proximal ilio-femoral DVT and low risk of bleeding complications to prevent PTS. 

Imaging-guided, catheter-based endovascular therapy has been used in selected patients to alleviate these sequelae, but important questions remain about their optimal use. In this article, we review the available evidence and summarize the rationale for use of catheter-based therapy in specific patient groups with acute iliofemoral DVT.

Catheter-directed thrombolysis and mechanical intervention in deep venous thrombosis: what is the status after the ATTRACT trial?

Deep venous thrombosis (DVT) is a major cause of acute and chronic morbidity, mortality, and increased healthcare costs. Endovascular methods for thrombus removal and reestablishing venous patency are increasing in both scope and usage. The most commonly used method for endovascular thrombectomy is catheter-directed thrombolysis (CDT). Several studies have shown promise for CDT in alleviating acute symptomatology in acute lower extremity DVT as well as mitigating potential long-term consequences of DVT, such as post-thrombotic syndrome (PTS). The Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial is the largest and most comprehensive randomized-controlled trial to date evaluating CDT compared to anticoagulation alone for the treatment of acute symptomatic proximal lower extremity DVT. This review discusses the current status of CDT and adjunctive endovascular interventions for DVT, particularly in the context of the ATTRACT trial.

Surgical Considerations in the Treatment of Axillary-Subclavian Venous Thrombosis in the Era of COVID-19

PURPOSE

Traditional treatment of axillary-subclavian venous thrombosis is resource intensive due to the need for advanced nursing care and increased utilization of intensive care units for thrombolysis procedures. We recently encountered this in the management of 2 patients with effort-induced upper extremity venous thrombosis following COVID-19 infection and offer a treatment paradigm for consideration.

CASE REPORTS

A 30-year-old presented with 2 weeks of left upper extremity symptoms following COVID-19 infection. Duplex ultrasound demonstrated axillary-subclavian venous thrombosis and venogram confirmed total occlusion of the axillary and subclavian veins with profuse collaterals around the occlusion. Suction thrombectomy was performed successfully and veins remained patent at 6 month follow up. The patient declined first rib resection and stopped lifting weights. A 16-year-old presented with 4 days of right arm symptoms 1 month after testing positive for COVID-19. Duplex ultrasound revealed acute axillary and subclavian vein thrombosis and she underwent successful thrombectomy followed by balloon angioplasty with improvement in symptoms.

CONCLUSION

The pandemic has strained health care resources such that the treatment of non-life-threatening conditions must be triaged to conserve resources. While axillary-subclavian venous occlusion is usually not life-threatening, timely treatment leads to decreased morbidity and better outcomes. Percutaneous aspiration and thrombectomy without adjunctive thrombolysis may be of benefit in reducing healthcare resource utilization while still achieving good outcomes during the COVID pandemic and beyond.

Pharmacologic and Pharmacomechanical Thrombolysis for Acute Deep Vein Thrombosis: Focus on ATTRACT CME

Systemically delivered pharmacologic thrombolysis for acute deep vein thrombosis long ago gave way to catheter delivery of plasminogen activators within the clot. This simple concept resulted in markedly improved efficacy and safety. In an effort to accelerate thrombus dissolution or extraction, mechanical methods were developed, but the initial techniques left substantial residual thrombus that required subsequent catheter-directed thrombolysis (CDT). It was soon observed that combined pharmacomechanical thrombolysis was more effective than either one alone. Randomized trials of catheter-based strategies for thrombus removal have documented objective benefit, including improved patency, preserved valve function, and reduced post-thrombotic syndrome. The largest randomized study is the ATTRACT trial published at the end of 2017. Although mild post-thrombotic syndrome (PTS) was no different between the pharmacomechanical catheter-directed thrombolysis (PCDT) and control groups, acute pain and swelling and moderate-to-severe PTS were reduced with PCDT. Additional analyses from this robust data set are forthcoming.

Thrombectomy and thrombolysis for the prevention and treatment of postthrombotic syndrome

Postthrombotic syndrome (PTS) is a frequent complication of lower-extremity deep vein thrombosis (DVT), occurring in approximately 40% of patients despite the use of anticoagulant therapy. PTS causes significant impairment of patients' health-related quality of life, and no evidence-based therapies have been consistently effective. Catheter-directed thrombolysis and thrombectomy have been shown to remove acute thrombus, and it has been hypothesized they could prevent or reduce PTS. However, because these procedures can be associated with complications, mainly bleeding, randomized trial data are needed to determine when they should be used. In this article, I summarize the current status of thrombus removal procedures for DVT to provide contemporary guidance to clinicians seeking to individualize treatment decisions for their patients.

Fixed low-dose ultrasound-assisted catheter-directed thrombolysis followed by routine stenting of residual stenosis for acute ilio-femoral deep-vein thrombosis

Patients with ilio-femoral deep-vein thrombosis (DVT) are at high risk of developing the postthrombotic syndrome (PTS). In comparison to anticoagulation therapy alone, extended venography-guided catheter-directed thrombolysis without routine stenting of venous stenosis in patients with ilio-femoral DVT is associated with an increased risk of bleeding and a moderate reduction of PTS. We performed a prospective single-centre study to investigate safety, patency and incidence of PTS in patients with acute iliofemoral DVT treated with fixed-dose ultrasound-assisted catheter-directed thrombolysis (USAT; 20 mg rt-PA during 15 hours) followed by routing stenting of venous stenosis, defined as residual luminal narrowing >50%, absent antegrade flow, or presence of collateral flow at the site of suspected stenosis. A total of 87 patients (age 46 ± 21 years, 60% women) were included. At 15 hours, thrombolysis success ≥50% was achieved in 67 (77%) patients. Venous stenting (mean 1.9 ± 1.3 stents) was performed in 70 (80%) patients, with the common iliac vein as the most frequent stenting site (83%). One major (1%; 95% CI, 0–6%) and 6 minor bleedings (7%; 95%CI, 3–14%) occurred. Primary and secondary patency rates at 1 year were 87% (95% CI, 74–94%) and 96% (95% CI, 88–99%), respectively. At three months, 88% (95% CI, 78–94%) of patients were free from PTS according to the Villalta scale, with a similar rate at one year (94%, 95% CI, 81–99%). In conclusion, a fixed-dose USAT regimen followed by routine stenting of underlying venous stenosis in patients with iliofemoral DVT was associated with a low bleeding rate, high patency rates, and a low incidence of PTS.

Factors Associated with Contralateral Deep Venous Thrombosis after Iliocaval Venous Stenting

BACKGROUND

The majority of iliac venous obstructions occur on the left side, and endovascular therapy has become the first line treatment for this condition. A left common iliac venous stent will protrude into the inferior vena cava (IVC) to some extent, thereby covering the contralateral common iliac vein (CIV) outflow. This may increase the risk of thrombosis of the contralateral iliac vein. The aim of this paper was to determine the rate of, and factors associated with, contralateral lower limb venous thrombosis after stenting, and to evaluate the results of salvage revascularisation.

METHODS

A total of 376 patients (102 from UCH, Galway, Ireland, 2008-16, and 274 from, CHU Nord, Marseille, France, 2000-15) with symptomatic acute or chronic left iliocaval venous obstruction were retrospectively evaluated. Either duplex ultrasound scanning (DUS) or computed tomographic venography (CTV) was used for pre- and post-operative imaging. Data were collected from the PACS system (IMPAX, Agfa, BE) of the Radiology Department, UCH, Galway, and from the electronic medical records of Vascular Surgery department, CHU Nord, Marseille.

RESULTS

The median age of stented patients was 46 (range 15-86 years), 80% were female (301/376). Following left CIV stent placement, 10 patients later presented with a right (contralateral) iliac deep venous thrombosis (DVT) resulting in a cumulative incidence of contralateral DVT of 4% according to Kaplan-Meier analysis. Acute DVT (p=.001), non-compliance with the prescribed 6 months anticoagulation (p = 0.05), pre-operative contralateral internal iliac vein (IIV) thrombosis (p = 0.001), and pre-existing IVC filter placement (p = 0.003) were all statistically significantly associated with contralateral DVT. All patients with symptomatic contralateral iliac DVT underwent clot removal in the acute phase. The primary patency of these limbs was 100% at 3 years.

CONCLUSION

Stent placement across the iliocaval confluence from the left CIV is associated with a low but definite rate of contralateral iliac vein thrombosis. Acute DVT, pre-operative contralateral IIV thrombosis, pre-existing IVC filters, and anticoagulation non-compliance are significant risk factors.

Non-Invasive Thrombolysis Using Microtripsy in a Porcine Deep Vein Thrombosis Model

Histotripsy is a non-invasive therapeutic technique that uses ultrasound generated from outside the body to create controlled cavitation in targeted tissue, and fractionates it into acellular debris. We have developed a new histotripsy approach, termed microtripsy, to improve targeting accuracy and to avoid collateral tissue damage. This in vivo study evaluates the safety and efficacy of microtripsy for non-invasive thrombolysis in a porcine deep vein thrombosis model. Acute thrombi were formed in left femoral veins of pigs (∼35 kg) by occluding the vessel using two balloon catheters and infusing with thrombin. Guided by real-time ultrasound imaging, microtripsy thrombolysis treatment was conducted in 14 pigs; 10 pigs were euthanized on the same day (acute) and 4 at 2 wk (subacute). To evaluate vessel damage, 30-min free-flow treatment in the right femoral vein (no thrombus) was also conducted in 8 acute pigs. Blood flow was successfully restored or significantly increased after treatment in 13 of the 14 pigs. The flow channels re-opened by microtripsy had a diameter up to 64% of the vessel diameter (∼6 mm). The average treatment time was 16 min per centimeter-long thrombus. Only mild intravascular hemolysis was induced during microtripsy thrombolysis. No damage was observed on vessel walls after 2 wk of recovery, venous valves were preserved, and there was no sign of pulmonary embolism. The results of this study indicate that microtripsy has the potential to be a safe and effective treatment for deep vein thrombosis in a porcine model.

Bechstein W, Reinisch A. Deep Vein Thrombosis of the Upper Extremity

BACKGROUND

Deep venous thrombosis (DVT) arises with an incidence of about 1 per 1000 persons per year; 4-10% of all DVTs are located in an upper extremity (DVT-UE). DVT-UE can lead to complications such as post-thrombotic syndrome and pulmonary embolism and carries a high mortality.

METHODS

This review is based on pertinent literature, published from January 1980 to May 2016, that was retrieved by a systematic search, employing the PRISMA criteria, carried out in four databases: PubMed (n = 749), EMBASE (n = 789), SciSearch (n = 0), and the Cochrane Library (n = 12). Guidelines were included in the search.

RESULTS

DVT-UE arises mainly in patients with severe underlying diseases, especially cancer (odds ratio [OR] 18.1; 95% confidence interval [9.4; 35.1]). The insertion of venous catheters-particularly central venous catheters-also elevates the risk of DVT-UE. Its clinical manifestations are nonspecific. Diagnostic algorithms are of little use, but ultrasonography is very helpful in diagnosis. DVT-UE is treated by anticoagulation, with heparin at first and then with oral anticoagulants. Direct oral anticoagulants are now being increasingly used. The thrombus is often not totally eradicated. Anticoagulation is generally continued as maintenance treatment for 3-6 months. Interventional techniques can be used for special indications. Patients with DVT-UE have a high mortality, though they often die of their underlying diseases rather than of the DVT-UE or its complications.

CONCLUSION

DVT of the upper extremity is becoming increasingly common, though still much less common than DVT of the lower extremity. The treatment of choice is anticoagulation, which is given analogously to that given for DVT of the lower extremity.

Effect of pulse repetition frequency of high-intensity focused ultrasound on in vitro thrombolysis

Vascular occlusion by the thrombi is the main reason for ischemic stroke and deep vein thrombosis. High-intensity focused ultrasound (HIFU) and histotripsy or microtripsy pulses can effectively dissolve the blood clot with no use of thrombolytic agent and ultrasound contrast agent (microbubbles). In this study, HIFU bursts at the same duty cycle (2%) but varied pulse repetition frequency (PRF) from 1Hz to 1000Hz were delivered to in vitro porcine blood clot for 30s. Thrombolysis efficiency initially increases slightly with the PRF, 86.4±10.3%, 89.9±11.9, and 92.9±12.8% at the PRF of 1Hz, 10Hz, and 100Hz, respectively, without significant difference (p>0.05), but then drops dramatically to 37.9±6.9% at the PRF of 1000Hz (p<0.05). The particle size in the supernatant of dissolution is 547.1±129.5nm, which suggests the disruption of thrombi into the subcellular level. Thrombi motion during HIFU exposure shows violent motion and significant curling at the low PRF, rotation about its axis with occasional curling at the moderate PRF, and localized vibration at the high PRF due to the generation of acoustic radiation force and streaming. Quantitative analysis of recorded motion shows the axial displacement decreases with the PRF of delivered HIFU bursts, from 3.9±1.5mm at 1Hz to 0.7±0.4mm at 1000Hz. Bubble cavitation during HIFU exposure to the blood clot was also monitored. The increase of PRF led to the increase of inertial cavitation but the decrease of stable cavitation. In summary, the PRF of delivered HIFU bursts at the same output energy has a significant effect on the thrombi motion, bubble cavitation activities, and subsequently thrombolysis efficiencies.

Interventional Management of Venous Thromboembolism: State of the Art

OBJECTIVE

The purpose of this article is to describe the indications for and approach to catheter-based treatment of acute venous thromboembolism (VTE).

CONCLUSION

Catheter-based treatment of VTE is a viable adjunct to anticoagulant therapy and is being rapidly adopted around the United States. Early data suggest that these therapies reduce postthrombotic sequelae and improve quality of life, but bleeding events are still frequent, particularly at low-volume centers. Protocols need to be standardized to improve patient care.

Inferior Vena Cava Thrombosis

Thrombosis of the inferior vena cava (IVC) is an under-recognized entity that is associated with significant short- and long-term morbidity and mortality. In absence of a congenital anomaly, the most common cause of IVC thrombosis is the presence of an unretrieved IVC filter. Due to the substantial increase in the number of IVC filters placed in the United States and the very low filter retrieval rates, clinicians are faced with a very large population of patients at risk for developing IVC thrombosis. Nevertheless, there is a paucity of data and societal guidelines with regards to the diagnosis and management of IVC thrombosis. This paper aims to enhance the awareness of this uncommon, but morbid, condition by providing a concise, yet comprehensive, review of the etiology, diagnostic approaches, and treatment strategies in patients with IVC thrombosis.

Guidance for the use of thrombolytic therapy for the treatment of venous thromboembolism

Patients with venous thromboembolism (VTE) are prone to the development of both short-term and long-term complications that can substantially affect their functional capacity and quality of life. Patients with deep vein thrombosis (DVT) often develop recurrent VTE or the post-thrombotic syndrome, whereas patients with pulmonary embolism (PE) can develop long-term symptoms and functional limitations along a broad spectrum extending to full-blown chronic thromboembolic pulmonary hypertension. Clinicians who care for patients showing severe clinical manifestations of DVT and PE are often faced with challenging decisions concerning whether and how to escalate to more aggressive treatments such as those involving the use of thrombolytic drugs. The purpose of this chapter is to provide guidance on how best to individualize care to these patients.

Catheter-directed thrombolysis for extensive iliofemoral deep vein thrombosis: review of literature and ongoing trials

In patients with extensive lower limb deep vein thrombosis (DVT) that, typically, extends into the iliofemoral veins, catheter-directed thrombolysis (CDT) can achieve faster and more complete thrombus lysis as compared with systemic thrombolysis, while providing an acceptable safety profile through administration of lower doses of thrombolytic agents. Through a reduction in thrombus burden, CDT has the potential to mitigate the risk for post-thrombotic syndrome by restoring venous patency and preserving venous valve function. The efficacy of CDT may be improved by adjunctive approaches that include percutaneous mechanical thrombectomy, angioplasty with or without stenting, and ultrasound-assisted CDT. CDT may also have a specific therapeutic role in the management of iliofemoral DVT involving patients who are pregnant or with May-Thurner syndrome. This article summarizes the literature in this area and discusses recently completed and ongoing randomized trials on the use of CDT in patients with extensive lower limb DVT.

Thrombolysis and iliofemoral vein stent placement in cancer patients with lower extremity swelling attributed to lymphedema

PURPOSE

To assess the effects of iliofemoral vein stent placement on symptomatic lower extremity swelling (LES), presumed to be lymphedema, in patients with cancer.

MATERIALS AND METHODS

During the period 2005-2013, 62 patients (38 female; age, 60.4 y ± 15.4) with histology-proven metastatic disease and LES resistant to standard therapies were evaluated and found to have venous outflow obstruction. Stents were placed in the iliofemoral veins or inferior vena cava, or both, and evaluated by color Doppler ultrasound or contrast-enhanced computed tomography during the follow-up period. Patient symptoms were assessed using the Venous Disability Score (VDS) and the Galway Limb Swelling score, a patient-directed, 5-question symptom scoring system.

RESULTS

Stents were successfully placed in all patients. During the follow-up period, in-stent thrombosis occurred in 13 patients, and additional stents were placed in 3 patients to treat luminal narrowing. The mean VDS improved significantly (P < .05): from 3.0 ± 0 on the day of the procedure to 2.95 ± 0.22 on day 3, 2.0 ± 0.33 on day 7, and 1.87 ± 0.34 on day 30. The mean Galway Limb Swelling score also improved significantly (P < 0.001): from 3.6 ± 0.74 on the day of the procedure to 1.96 ± 0.91 on day 3, 1.06 ± 0.78 on day 7, and 0.6 ± 0.66 on day 30. During the follow-up period, 60 patients died as a result of their underlying malignancy (mean, 230 d; range, 5-1,080 d).

CONCLUSIONS

Iliofemoral or iliocaval venous stent placement may have a valuable role in patients with metastatic disease and symptomatic LES associated with venous obstruction.

Endovascular Interventions for Acute and Chronic Lower Extremity Deep Venous Disease: State of the Art

The societal and individual burden caused by acute and chronic lower extremity venous disease is considerable. In the past several decades, minimally invasive endovascular interventions have been developed to reduce thrombus burden in the setting of acute deep venous thrombosis to prevent both short- and long-term morbidity and to recanalize chronically occluded or stenosed postthrombotic or nonthrombotic veins in symptomatic patients. This state-of-the-art review provides an overview of the techniques and challenges, rationale, patient selection criteria, complications, postinterventional care, and outcomes data for endovascular intervention in the setting of acute and chronic lower extremity deep venous disease. Online supplemental material is available for this article.

A Multicenter, Retrospective Study of the Effectiveness of the Trellis-8 System in the Treatment of Proximal Lower-Extremity Deep Vein Thrombosis

BACKGROUND

Deep vein thrombosis (DVT) occurs in up to 600,000 patients in the United States annually and can lead to long-term morbidity because of the post-thrombotic syndrome. The multicenter isolated-pharmacomechanical thrombolysis device (ISOL-8) study was designed to determine the safety and efficacy of the Trellis™-8 peripheral infusion system when used as the primary intervention to achieve DVT thrombolysis in patients with proximal lower-extremity occlusive DVT, and track the incidence and severity of the post-thrombotic syndrome (PTS) symptoms in patients 2 years after treatment.

METHODS

Data were collected retrospectively from 6 centers on patients treated with the Trellis-8 system, an isolated-pharmacomechanical thrombolysis device (IPMTD). Patients with occlusive lower-extremity DVT involving at least the iliac and/or common femoral vein were included. Patient demographics, medical history, procedure outcomes, complications, and follow-up venous duplex and Venous Clinical Severity Score (VCSS) were collected through 24 months. Data analysis of outcomes were performed at 1 and 12 months. A 24-month analysis was not performed because of the small number of patients for whom 24-month data could be collected.

RESULTS

A total of 151 limbs in 139 patients were treated with IPMTD. The mean ± standard deviation (SD) procedure time was 122.6 ± 63.4 min. Single session treatment was delivered in 69.9% (93 of 133) of cases. Occlusive DVT extended from the femoral into the external and/or common iliac vessel segments in most of the cases (113 of 151 limbs; 74.8%). Before treatment, 23.2% (35 of 151) of the treated limbs, based on a history of prior ipsilateral DVT or preoperative imaging revealing chronic venous scar, were expected to have some chronic venous disease despite presenting with acute symptoms. After treatment, 43.7% (66 of 151) of the limbs showed evidence of chronic thrombus. The average amount (mean ± SD) of thrombolysis, as determined by venogram, was highest in patients who had acute thrombus (81 ± 19.7%), compared with subacute thrombus (61 ± 22.5%) and complex cases involving acute and/or subacute thrombus on chronic scar (56 ± 26.5%). VCSS scoring showed the number of patients with none and/or mild pain, varicose veins, and skin changes at 1-month remained stable at 12 months whereas the percent of patients with none and/or mild venous edema improved from 71.7% at 1 month (38 of 53) to 86.8% (46 of 53) at 12 months. Twenty-four-month follow-up data were available for only 15% (23 of 151) of patients. No clinically significant pulmonary emboli or major periprocedural bleeding events were reported.

CONCLUSIONS

Patients with acute lower-extremity DVT involving the proximal veins can be safely and successfully treated with IPMTD. Major procedural bleeding was absent. The occurrence of severe PTS after primary treatment with Trellis-8 system IPMTD is low. Further long-term follow-up data are needed to confirm the benefit of intervention for thrombus removal compared with standard medical management.

Pharmacomechanical Thrombolysis in the Management of Acute Inferior Vena Cava Filter Occlusion Using the Trellis-8 Device

Purpose: To evaluate the performance and safety of the Trellis-8 system, a pharmacomechanical thrombolysis infusion catheter, and adjunctive therapies in the treatment of symptomatic inferior vena cava (IVC) filter–related acute thrombotic occlusion. Methods: Eight consecutive patients (6 men; mean age 57.4 years, range 34–78 years) with acute thrombotic occlusion of the IVC in the presence of an IVC filter underwent percutaneous venous thrombectomy using the Trellis-8 thrombectomy system and adjunctive techniques between January 2009 and November 2013. Demographics, clinical data, procedures, and outcomes were retrospectively reviewed. All patients had clinical signs of lower extremity venous hypertension on presentation. The median time between IVC filter placement and occlusion was 25 months. Patients were followed for the development of thromboembolic complications to the last clinic visit or until they died. Results: The procedure was technically successful in 6 patients, whereas it could not be performed in 2 due to failure to cross the occlusion. The median follow-up period was 7.8 months, at which time all patients undergoing successful Trellis-8 thrombectomy had relief of symptoms without thromboembolic or bleeding complications. Conclusion: In this limited performance and safety evaluation, the Trellis-8 thrombectomy system combined with adjunctive therapies, such as mechanical thrombectomy and balloon angioplasty, was effective in 75% of patients with IVC filter–related acute caval occlusion.

Pharmacomechanical thrombolysis of symptomatic acute and subacute deep vein thrombosis with a rotational thrombectomy device

PURPOSE

To retrospectively evaluate the efficacy and safety of pharmacomechanical thrombolysis (PMT) with the use of a rotational thrombectomy device for symptomatic deep vein thrombosis (DVT).

MATERIALS AND METHODS

Between July 2012 and August 2013, 41 patients with acute or subacute DVT underwent PMT. The Cleaner thrombectomy device was used in a single-session technique for patients with lower-extremity DVT. Based on contrast venography, the extent of lysis was graded from I (< 50%) to III (complete).

RESULTS

Sixteen patients (39.0%) had a femoropopliteal thrombosis and 25 (61.0%) had an iliofemoral venous thrombosis. The mean duration of symptoms was 11.0 days (range, 3-25 d). The mean quantity of tissue plasminogen activator was 20.7 mg (range, 10-50), and the mean duration of the procedure was 74.3 minutes (range, 30-240 min). At the end of the PMT procedure, 29 patients (70.7%) had complete (grade III) thrombus resolution. Grade I and II lysis were noted in one (2.4%) and 11 (26.8%) patients, respectively. Thirty-eight of the 41 patients were treated with PMT in a single session, and three (7.3%) required an additional lytic infusion as a result of residual thrombi. The overall grade III, II, and I thrombus resolution rates, including the supplemental thrombolysis, were 73.2% (n = 30), 22.0% (n = 9), and 4.9% (n = 2), respectively. There was no mortality.

CONCLUSIONS

Use of the Cleaner thrombectomy device is a promising alternative to current treatment modalities for the management of DVT in a single session of PMT.

Endovascular Treatment of Deep Vein Thrombosis

Venous thromboembolism (VTE) is associated with substantial morbidity and mortality. Conventional treatment with anticoagulation therapy may undertreat the condition. Patients with VTE are at risk for recurrence with increasing time passage. Endovascular approaches exist for treating VTE, including deep vein thrombosis, but it is unclear which patients are appropriate candidates for endovascular versus medical approaches. Many new endovascular technologies are in development, and new oral anticoagulants are also on the market. Clinicians must be mindful of these new products and use them appropriately to better manage VTE.

In vitro demonstration of focused ultrasound thrombolysis using bifrequency excitation

Focused ultrasound involving inertial cavitation has been shown to be an efficient method to induce thrombolysis without any pharmacological agent. However, further investigation of the mechanisms involved and further optimization of the process are still required. The present work aims at studying the relevance of a bifrequency excitation compared to a classical monofrequency excitation to achieve thrombolysis without any pharmacological agent. In vitro human blood clots were placed at the focus of a piezoelectric transducer. Efficiency of the thrombolysis was assessed by weighing each clot before and after sonication. The efficiencies of mono- (550 kHz) and bifrequency (535 and 565 kHz) excitations were compared for peak power ranging from 70 W to 220 W. The thrombolysis efficiency appears to be correlated to the inertial cavitation activity quantified by passive acoustic listening. In the conditions of the experiment, the power needed to achieve 80% of thrombolysis with a monofrequency excitation is reduced by the half with a bifrequency excitation. The thermal effects of bifrequency and monofrequency excitations, studied using MR thermometry measurements in turkey muscle samples where no cavitation occurred, did not show any difference between both types of excitations when using the same power level.

Treating infrainguinal deep venous thrombosis

Endovascular DVT therapy has historically been directed at patients with the most extensive DVT. As evidence has been developed to support the use of catheter-directed thrombolysis for iliofemoral DVT, interventional radiologists are increasingly being referred patients with DVT that is anatomically less severe. In this article, we outline the key considerations that should be weighed in determining whether or not to provide aggressive therapy to patients with DVT limited to the femoropopliteal veins.

Catheter-directed thrombolysis for iliofemoral deep vein thrombosis

BACKGROUND

Recent international guidance recommends the use of catheter-directed thrombolysis (CDT) in selected patients with symptomatic iliofemoral deep vein thrombosis (DVT). The aim of this study was to estimate the potential increase in workload as a result of this recommendation.

METHODS

Using the radiology database, a review was performed of all DVTs diagnosed between August 2010 and February 2012 at a large tertiary referral hospital. The National Institute for Health and Clinical Excellence and American College of Chest Physicians guidance was applied retrospectively to this cohort, using case-note review by two independent clinicians to determine which patients would have been suitable for CDT.

RESULTS

Some 563 patients had DVT confirmed radiologically over the 18-month interval. Fifty-three of the 128 patients with iliofemoral DVT would have been eligible for intervention with CDT, equivalent to 4·4 patients per 100 000 per year. Only eight (15 per cent) of the 53 were actually referred to vascular services for treatment. All eight patients had successful CDT, which involved a stay in critical care for monitoring (median 2 (range 1-3) sessions).

CONCLUSION

Vascular units should be prepared for a major increase in the requirement for CDT for iliofemoral DVT. This increase will affect inpatient beds, the interventional radiology suite, critical care and interhospital referrals.

Pharmacomechanical thrombolysis in the management of paget-schroetter syndrome

Paget-Schroetter syndrome (PSS) is a rare form of thoracic outlet syndrome caused by axillosubclavian vein thrombosis which typically presents in healthy young adults. Prompt therapy, traditionally by means of catheter-directed thrombolysis (CDT) prior to definitive surgery, can prevent the subsequent onset of postthrombotic syndrome (PTS) and considerable disability. As CDT is associated with major haemorrhage and high overall treatment cost, pharmacomechanical thrombectomy (PMT) seems to be an attractive alternative which combines pharmacological thrombolysis with mechanical clot disruption. The Trellis-8 peripheral infusion catheter is an example of such a treatment which provides topical thrombolysis in an isolated zone. We describe the use of the Trellis-8 PMT system in the successful management of three patients with PSS.

Use of a Trellis device for endovascular treatment of venous thrombosis involving a duplicated inferior vena cava

Congenital anomalies of the inferior vena cava (IVC) are increasingly recognized with CT and venography techniques. Although many patients with IVC anomalies are asymptomatic, recent studies have suggested an association with venous thromboembolism. We report the case of a 62-year-old woman with extensive venous clot involving the infrarenal segment of a duplicated left IVC who underwent pharmacomechanical thrombectomy and tissue plasminogen activator catheter-directed thrombolysis with complete deep venous thrombosis resolution. To our knowledge this is the first reported case in the English literature of the use of a Trellis thrombectomy catheter in the setting of duplicated IVC.

Removing vascular obstructions: a challenge, yet an opportunity for interventional microdevices

Cardiovascular diseases are the leading cause of death worldwide; they are mainly due to vascular obstructions which, in turn, are mainly caused by thrombi and atherosclerotic plaques. Although a variety of removal strategies has been developed for the considered obstructions, none of them is free from limitations and conclusive. The present paper analyzes the physical mechanisms underlying state-of-art removal strategies and classifies them into chemical, mechanical, laser and hybrid (namely chemo-mechanical and mechano-chemical) approaches, while also reviewing corresponding commercial/research tools/devices and procedures. Furthermore, challenges and opportunities for interventional micro/nanodevices are highlighted. In this spirit, the present review should support engineers, researchers active in the micro/nanotechnology field, as well as medical doctors in the development of innovative biomedical solutions for treating vascular obstructions. Data were collected by using the ISI Web of Knowledge portal, buyer's guides and FDA databases; devices not reported on scientific publications, as well as commercial devices no more for sale were discarded. Nearly 70% of the references were published since 2006, 55% since 2008; these percentages respectively raise to 85% and 65% as regards the section specifically reviewing state-of-art removal tools/devices and procedures.

Biochemical dynamics relevant to the safety of low-dose, intraclot alteplase for deep vein thrombosis

Intraclot tissue plasminogen activator (tPA) has been shown to be an effective treatment for deep vein thrombosis (DVT) (Radiology 2008;246:619 and J Vasc Interv Radiol 2011;22:1107). We sought to correlate pharmacokinetics of tPA, fibrinogen, fibrinolytic inhibitors, and D-dimers with the safety and efficacy of intraclot tPA. Thirty subjects received intraclot tPA for lower extremity DVT by infiltrating the thrombus with ≤10 mg doses tPA in an open-label study, using a pulse-spray catheter. We measured various parameters over 8 h following a first dose of tPA. Mean tPA levels of 75 units per mL (95% confidence interval 19-131 units/mL) were seen immediately after administration of a mean tPA dose of 8.0 mg (SD 1.5 mg). tPA levels returned to baseline within 2 h of completion of treatment. Plasminogen activator inhibitor-1 (PAI-1) was consumed following tPA treatment, but rose to levels significantly greater than baseline (P < 0.001). Fibrinogen decreased slightly, but remained >125 mg/dL for all subjects. α2-antiplasmin decreased from a mean of 115 units/mL to 56 units/mL after tPA administration (P < 0.001) and remained decreased for 8 h. Plasminogen at baseline (112 units/mL) decreased to 89 units/mL immediately after tPA administration (P < 0.001) and was unchanged thereafter. D-dimer levels were >20 μg/mL in all but 4 subjects, one of whom was the only one to fail to achieve clot lysis. The safety of low-dose, intraclot tPA is due to its short persistence in the circulation, lack of hypofibrinogenemia, and a reflexive rise of PAI-1. Subjects whose D-dimers remain <20 μg/mL are at risk of not achieving thrombolysis.

Endovascular management of acute upper extremity deep venous thrombosis and the use of superior vena cava filters

Upper extremity deep venous thrombosis (UEDVT), though less common than lower extremity DVT, is a significant problem with several possible etiologies. The incidence of UEDVT is on the rise, primarily from the increasing use of central venous access devices. However, there are other causes of UEDVT, including primary venous thrombosis (Paget-Schroetter syndrome) and hypercoagulable states associated with underlying malignancy. The morbidity and mortality associated with UEDVT is largely from pulmonary embolism and the postphlebitic syndrome. Nevertheless, many UEDVTs are asymptomatic or patients may present with nonspecific clinical symptoms; therefore, a high index of suspicion is often necessary to make a correct diagnosis. Currently, there is no standard treatment algorithm for UEDVT. Treatment options may range from systemic anticoagulation to surgical correction depending on the etiology of the thrombus, as well as the patient's associated comorbidities, life expectancy and expected quality of life following treatment.

Interventional approaches to deep vein thrombosis

The last decade has seen increased use of aggressive, catheter-based methods of treating deep vein thrombosis (DVT). In this article, we outline the risks, benefits, and uncertainties surrounding endovascular DVT therapies, describe clinical situations in which endovascular treatment options should reasonably be considered, and update the reader on new outcome data that pertains to catheter-based DVT interventions. Endovascular thrombolytic therapy is reasonable to perform for selected patients with DVT causing acute limb-threatening circulatory compromise, acute inferior vena cava occlusion, or acute iliofemoral DVT for the purposes of limb salvage and relief of presenting DVT symptoms, and appears likely to prevent post-thrombotic syndrome (PTS) in patients with proximal DVT. A multicenter randomized trial, the ATTRACT Study, is currently underway in the United States to determine whether pharmacomechanical catheter-directed thrombolysis (PCDT) is sufficiently safe and effective to be recommended for routine use in proximal DVT patients. Selected patients with established moderate-to-severe PTS in association with an occluded iliac vein or a refluxing saphenous vein may also be amenable to endovascular intervention to reduce venous hypertension, alleviate symptoms, and improve limb function and quality of life. Pending the results of further studies, an individualized approach to patient selection for interventional DVT therapies is recommended.

Total preservation of patency and valve function after percutaneous pharmacomechanical thrombolysis using the Trellis®-8 system for an acute, extensive deep venous thrombosis

Pharmacomechanical thrombolysis is being used increasingly for the treatment of deep vein thrombosis (DVT) and aims to reduce the severity of post-thrombotic syndrome. We report the case of a 60-year-old woman with extensive lower limb DVT that was treated using pharmacomechanical thrombolysis leading to complete recovery of her deep venous system. The prompt use of pharmacomechanical thrombolysis for the acute management of extensive DVT should be considered when treating patients with extensive DVT in order to facilitate return of normal function.

An Imaging Approach to Deep Vein Thrombosis and the Lower Extremity Thrombosis Classification

In this article we want to discuss the potential of lower extremity deep vein thrombosis (DVT) imaging and propose a systematic approach to DVT management based on a DVT classification of the lower extremity; the LET classification. Identifying and reporting DVT more systematically allows for accurate stratification for initial patient care, future clinical trials and appropriate descriptions for natural history studies.

pharmacomechanical Thrombectomy for Early Thrombus Removal

Objectives:

To review the current literature on the outcomes of pharmacomechanical thrombectomy (PMT) for early thrombus removal in patients with venous thromboembolism (VTE).

Methods:

We searched the MEDLINE database and performed a manual search of the references of selected articles to select reports reporting the outcomes of PMT alone and PMT compared to catheter-direct thrombolysis (CDT). Outcomes of interest included clot lysis rate, incidence of pulmonary embolism, major bleeding, recurrent deep vein thrombosis, number of venograms needed and amount of lytic utilized.

Results

We found nine articles that reported outcomes of PMT. Three devices were utilized for PMT, the Angiojet, Trellis and Helix. Different thrombolytics were used to facilitate thrombus removal including urokinase, reteplase, tecneteplase, and tissue plasminogen activator (t-PA). Complete and partial thrombus removal were achieved in up to 84% and 64% and 81% and 59% of the limbs treated with PMT and CDT alone, respectively. Data on PE and bleeding risk after PMT compared to CDT are scarce. The duration of the thrombolysis process, amount of lytics and number of venograms were substantially reduced in the patients who had PMT compared to those who underwent CDT alone. Two articles evaluated the obstacles that limit the indication of PMT in patients with VTE.

Conclusion:

VTE is a prevalent burden in Western societies. The rationale of early thrombus is to reduce valvular damage and improve venous patency in order to reduce the risk of PTS. PMT is a feasible, safe and faster alternative to expedite the thrombolysis process in patients with VTE.

Endovascular Procedures in the Management of DVT

The post-thrombotic syndrome (PTS) develops in 25%-50% of patients with proximal lower extremity deep vein thrombosis (DVT) despite the use of standard anticoagulant therapy and elastic compression stockings. PTS is a major cause of quality of life impairment in DVT patients and often leads to limiting venous claudication, work disability, and venous ulcers. Endovascular thrombolytic procedures that eliminate venous thrombus, restore venous flow, and show strong potential to prevent PTS are now under study in multicenter randomized clinical trials. In addition, endovascular procedures can be used to treat valvular reflux and venous obstruction and thereby provide symptom improvement to patients with chronic established PTS.

[The role of thrombolysis in the clinical management of deep vein thrombosis]

Acute Deep Venous Thrombosis (DVT) therapies have been judged primarily on their ability to prevent symptomatic pulmonary embolism, early thrombus progression, and recurrent VTE. The cornerstones of current management of DVT, supported by the 2008 American College of Chest Physicians (ACCP) guidelines, are the routine use of anticoagulant therapy, graduated elastic compression stockings, and early ambulation. For selected appropriate patients with extensive acute proximal DVT, while the French recommendations (Afssaps 2009) still consider thrombolysis not indicated, ACCP guidelines now suggest in-situ thrombolysis in addition to anticoagulation to reduce the risk of subsequent postthrombotic syndrome (PTS) and recurrent DVT (Grade 2 B recommendation). Contemporary invasive endovascular treatments, called pharmacomechanical treatment, mitigate the drawbacks (major bleeding) historically associated with systemic thrombolytic approaches, by means of intra-thrombus delivery of drugs, followed by mechanical dispersion to accelerate lysis and then aspiration of remaining drug and clot debris. The proof of concept for the "open vein" hypothesis - that a strategy of early thrombus removal can reduce the incidence of PTS long term - comes incrementally and randomized trials (ATTRACT trial with a 2016 target completion date) are currently under way and might lead to a shift of the paradigms of the management of acute DVT focused on active thrombus removal.