The Clinical Rationale for the Sentry Bioconvertible Inferior Vena Cava Filter for the Prevention of Pulmonary Embolism.

The Sentry inferior vena cava (IVC) filter is designed to provide temporary protection against pulmonary embolism (PE) during transient high-risk periods and then to bioconvert after 60 days after implantation. At the time of bioconversion, the device's nitinol arms retract from the filtering position into the caval wall. Subsequently, the stable stent-like nitinol frame is endothelialized. The Sentry bioconvertible IVC filter has been evaluated in a multicenter investigational-device-exemption pivotal trial (NCT01975090) of 129 patients with documented deep vein thrombosis (DVT) or PE, or at temporary risk of developing DVT or PE, and with contraindications to anticoagulation. Successful filter conversion was observed in 95.7% of patients at 6 months (110/115) and 96.4% at 12 months (106/110). Through 12 months, there were no cases of symptomatic PE. The rationale for development of the Sentry bioconvertible device includes the following considerations: (1) the period of highest risk of PE for the vast majority of patients occurs within the first 60 days after an index event, with most of the PEs occurring in the first 30 days; (2) the design of retrievable IVC filters to support their removal after a transitory high-PE-risk period has, in practice, been associated with insecure filter dynamics and time-dependent complications including tilting, fracture, embolization, migration, and IVC perforation; (3) most retrievable IVC filters are placed for temporary protection, but for a variety of reasons they are not removed in any more than half of implanted patients, and when removal is attempted, the procedure is not always successful even with advanced techniques; and (4) analysis of Medicare hospital data suggests that payment for the retrieval procedure does not routinely compensate for expense. The Sentry device is not intended for removal after bioconversion. In initial clinical use, complications have been limited. Long-term results for the Sentry bioconvertible IVC filter are anticipated soon.

Durable Clinical Effectiveness With Paclitaxel-Eluting Stents in the Femoropopliteal Artery: 5-Year Results of the Zilver PTX Randomized Trial.

BACKGROUND: This randomized controlled trial evaluated clinical durability of Zilver PTX, a paclitaxel-coated drug-eluting stent (DES), for femoropopliteal artery lesions. Outcomes compare primary DES versus percutaneous transluminal angioplasty (PTA), overall DES (primary and provisional) versus standard care (PTA and provisional Zilver bare metal stent [BMS]), and provisional DES versus provisional BMS. METHODS AND RESULTS: Patients with symptomatic femoropopliteal artery disease were randomly assigned to DES (n=236) or PTA (n=238). Approximately 91% had claudication; 9% had critical limb ischemia. Patients experiencing acute PTA failure underwent secondary randomization to provisional BMS (n=59) or DES (n=61). The 1-year primary end points of event-free survival and patency showed superiority of primary DES in comparison with PTA; these results were sustained through 5 years. Clinical benefit (freedom from persistent or worsening symptoms of ischemia; 79.8% versus 59.3%, P<0.01), patency (66.4% versus 43.4%, P<0.01), and freedom from reintervention (target lesion revascularization, 83.1% versus 67.6%, P<0.01) for the overall DES group were superior to standard care in nonrandomized comparisons. Similarly, clinical benefit (81.8% versus 63.8%, P=0.02), patency (72.4% versus 53.0%, P=0.03), and freedom from target lesion revascularization (84.9% versus 71.6%, P=0.06) with provisional DES were improved over provisional BMS. These results represent >40% relative risk reduction for restenosis and target lesion revascularization through 5 years for the overall DES in comparison with standard care and for provisional DES in comparison with provisional BMS. CONCLUSIONS: The 5-year results from this large study provide long-term information previously unavailable regarding endovascular treatment of femoropopliteal artery disease. The Zilver PTX DES provided sustained safety and clinical durability in comparison with standard endovascular treatments. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00120406.

The RETRIEVE trial: safety and effectiveness of the retrievable crux vena cava filter.

PURPOSE: To evaluate the safety and effectiveness of the Crux vena cava filter in patients at risk for pulmonary embolism (PE). MATERIALS AND METHODS: The Crux Biomedical Evaluation of the Crux Inferior Vena Cava Filter System trial was an international prospective, multicenter, single-arm clinical trial in 125 patients implanted with the Crux filter between June 2010 and June 2011. Follow-up was 180 days after filter placement and 30 days after filter retrieval. The primary objective was to determine whether the clinical success rate was at least 80%. Clinical success was defined as technical success of deployment and freedom from definite PE, filter migration, and device-related adverse events requiring intervention. RESULTS: The clinical success rate was 96.0% (120 of 125), with a one-sided lower limit of the 95% confidence interval of 91.8%. The rate of technical success was 98.4% (123 of 125). There were three cases of definite PE (2.4%), two cases of deployment failure, and no cases of device migration, embolization, fracture, or tilting. Investigators observed nine cases of thrombus (all nonocclusive) in or near the filter (six during retrieval evaluation vena cavography, two during computed tomography [CT] scans for PE symptoms, and one during CT for cancer management) and 13 cases of deep vein thrombosis. Device retrieval was attempted at a mean of 84.6 days±57.6 (range, 6-190 d) after implantation and was successful for 98.1% of patients (53 of 54). All deaths (n = 14) were determined to be unrelated to the filter or PE. CONCLUSIONS: The Crux vena cava filter performed safely, with high rates of clinical, technical, and retrieval success.

Sustained safety and effectiveness of paclitaxel-eluting stents for femoropopliteal lesions: 2-year follow-up from the Zilver PTX randomized and single-arm clinical studies.

OBJECTIVES: A prospective, multinational randomized controlled trial (RCT) and a complementary single-arm study evaluated the 2-year safety and effectiveness of a paclitaxel-coated drug-eluting stent (DES) in patients with superficial femoral artery lesions. The RCT compared the DES with percutaneous transluminal angioplasty (PTA) and provisional bare-metal stent (BMS) placement. BACKGROUND: Local drug delivery for superficial femoral artery lesions has been investigated with the intent of limiting restenosis similarly to DES for the coronary arteries. One-year outcomes of DES in the superficial femoral artery are promising, but longer-term benefits have not been established. METHODS: In the RCT, patients were randomly assigned to primary DES implantation (n = 236) or PTA (n = 238). Acute PTA failure occurred in 120 patients, who underwent secondary randomization to DES (n = 61) or BMS (n = 59) placement. The single-arm study enrolled 787 patients with DES treatment. RESULTS: Compared with the control group, the primary DES group demonstrated significantly superior 2-year event-free survival (86.6% vs. 77.9%, p = 0.02) and primary patency (74.8% vs. 26.5%, p < 0.01). In addition, the provisional DES group exhibited superior 2-year primary patency compared with the provisional BMS group (83.4% vs. 64.1%, p < 0.01) and achieved higher sustained clinical benefit (83.9% vs. 68.4%, p = 0.05). Two-year freedom from target lesion revascularization with primary DES placement was 80.5% in the single-arm study and 86.6% in the RCT. CONCLUSIONS: Two-year outcomes with the paclitaxel-eluting stent support its sustained safety and effectiveness in patients with femoropopliteal artery disease, including the long-term superiority of the DES to PTA and to provisional BMS placement. (Evaluation of the Zilver PTX Drug-Eluting Stent in the Above-the-Knee Femoropopliteal Artery; NCT00120406; Zilver(®) PTX™ Global Registry; NCT01094678).

Paclitaxel-eluting stents show superiority to balloon angioplasty and bare metal stents in femoropopliteal disease: twelve-month Zilver PTX randomized study results.

BACKGROUND: Sustained benefits of drug-eluting stents in femoropopliteal arteries have not been demonstrated. This prospective, multinational, randomized study was designed to compare the 12-month safety and effectiveness of a polymer-free, paclitaxel-coated nitinol drug-eluting stent (DES) with percutaneous transluminal angioplasty (PTA) and provisional bare metal stent (BMS) placement in patients with femoropopliteal peripheral artery disease. METHODS AND RESULTS: Patients were randomly assigned to primary DES implantation (n=236) or PTA (n=238). Demographics and lesion characteristics were similar between groups (eg, average lesion length, approximately 65±40 mm). One hundred twenty patients had acute PTA failure and underwent secondary random assignment to provisional DES (n=61) or BMS (n=59). Primary end points were the 12-month rates of event-free survival and patency in the primary DES and PTA groups. Compared with the PTA group, the primary DES group exhibited superior 12-month event-free survival (90.4% versus 82.6%; P=0.004) and primary patency (83.1% versus 32.8%; P<0.001), satisfying the primary hypotheses. In the secondary evaluations, (1) the primary DES group exhibited superior clinical benefit compared with the PTA group (88.3% versus 75.8%; P<0.001), (2) the provisional DES group exhibited superior primary patency (89.9% versus 73.0%; P=0.01) and superior clinical benefit (90.5% and 72.3%, P=0.009) compared with the provisional BMS group, and (3) the stent fracture rate (both DES and BMS) was 0.9% (4/457). CONCLUSIONS: Femoropopliteal peripheral artery disease treatment with the paclitaxel-eluting stent was associated with superior 12-month outcomes compared with PTA and provisional BMS placement.

TASC II and the endovascular management of infrainguinal disease.

The stratifications of aortoiliac, femoropopliteal, and infrapopliteal lesions included in the original comprehensive report of the TransAtlantic Inter-Society Consensus (TASC I) have been commonly used to formally characterize clinical trial populations and to channel investigative discussion among clinicians, while the associated treatment recommendations have become outdated as compared to current clinical practice. The TASC II report is an abbreviated update focusing on key areas of diagnosis and management of peripheral artery disease, with revised stratifications of aortoiliac and femoropopliteal lesions but not infrapopliteal disease. The consensus document keeps new lesion stratifications linked to the same structure of recommendations for initial treatment: endovascular for type A, endovascular (with qualifications) for type B, open surgical (with qualifications) for type C, and open surgical for type D. In general, each TASC II lesion category includes more severe disease than in TASC I, but the TASC II report does not recommend specific endovascular modalities for infrainguinal occlusive disease. We discuss how the new TASC II femoropopliteal lesion categories reflect current research outcomes and clinical practice, including summarized results from some more recent studies that have demonstrated the ability to treat by endovascular means increasingly complex femoropopliteal lesions that would actually be classifiable as type C. Noting that TASC II does not include a separate stratification of infrapopliteal lesions, as did TASC I, we review evidence of recent endovascular treatment of infrapopliteal lesions and contend that TASC classifications in this anatomical area should be upgraded.

Long-term retrieval success rate profile for the Günther Tulip vena cava filter.

PURPOSE: To evaluate the likelihood of successful retrieval of the Günther Tulip vena cava filter after various implant durations (up to 494 days). MATERIALS AND METHODS: Retrievable Günther Tulip filters were placed in 554 patients. All patients satisfied requirements for filter placement; the primary indication for placement was specified for 394 patients (71%), as follows: unspecified trauma (n = 164), bariatric procedures (n = 128), orthopedic procedures (n = 36), and other (n = 66). Filter tilt and vena cava injury were assessed at implantation. Filters were not repositioned after placement. At retrieval, filter orientation, vena cava injury, other device-related incidents, and the degree of difficulty associated with retrieval were reported. RESULTS: Filter retrieval was attempted in 275 patients and successful in 248 (90.2%). The mean filter indwell time was 58.9 days (range, 3-494 days). Unsuccessful retrievals (n = 27) were attributed primarily to improper hook orientation (n = 10) or excessive tissue in-growth at the filter legs (n = 16). Of the remaining 279 patients, 223 withdrew from the study, 41 were associated with a decision to keep the filter as a permanent device, 13 died for reasons unrelated to the study, and two had no reported endpoint data. A Kaplan-Meier product-limit survival estimate revealed that the probability of successful device retrieval remained greater than 94% at 12 weeks and greater than 67% at 26 weeks. CONCLUSIONS: This study contributes to the body of clinical data related to retrievable filters, demonstrating reliable retrieval rates at 12 weeks, with successful retrievals up to 17 months after implantation.

Deployment performance and retrievability of the Cook Celect vena cava filter.

PURPOSE: To test the safety, performance, and retrievability of the Cook Celect vena cava filter. MATERIALS AND METHODS: Twenty female or castrated male sheep were implanted with two Celect filters in series, in the inferior vena cava. The animals were divided into five groups of four animals according to day of filter retrieval. Filter retrieval occurred at approximately 30, 60, 90, 180, and 360 days after implantation. At each time point, two sheep underwent retrieval attempts of both the cranial and caudal filters. These animals were recovered for 30 days, at which time healing was assessed. In two additional sheep at each time point, retrieval of only the cranial filter was attempted and the caudal filter was left in situ. These sheep were euthanized after retrieval, and the segment of vena cava encompassing the sites of both the retrieved filter and the filter left in situ was excised for gross and histopathologic analysis. RESULTS: Retrieval attempts occurred at 34, 62, 90, 188, and 393 days after implantation. All retrievals were successful (30 of 30). Tilt was detected in eight filters at implantation; six had self-centered before retrieval. At retrieval, no filter migration or deformation was reported. All filters were retrieved with acceptable levels of force. At each time point, there was evidence of mild intimal hyperplasia at the filter anchoring sites and no evidence of vena cava injury. CONCLUSIONS: The Celect vena cava filter was safely used as a retrievable filter for up to 393 days in an ovine model.

Fracture of self-expanding nitinol stents stressed in vitro under simulated intravascular conditions.

OBJECTIVE: The use of intravascular stents in the superficial femoral artery (SFA) continues to be controversial due to the potential for compression and fracture in the tortuous physical environment of the adductor canal. The purpose of this study was to (1) characterize the types and ranges of stent distortion theoretically produced by extremity movement and (2) use these ranges as parameters for in vitro long-term fatigue testing of commercially available self-expanding nitinol stents. METHODS: Nitinol self-expanding stents were placed in the SFAs of cadavers and lateral view radiographs were obtained with the limb in various degrees of hip and knee flexion. The measured degrees of axial shortening and bending of the stent were estimated by planimetry and used for in vitro fatigue testing, which was undertaken using specially designed equipment. Six different commercially available nitinol self-expanding stents-Protégé EverFlex (EV3, Minneapolis, Minn), S.M.A.R.T. Control (Cordis/Johnson & Johnson, Miami Lakes, Fla), Luminexx (C.R. Bard, Murray Hill, NJ), LifeStent FlexStar (Edwards Lifesciences, Irvine, Calif), and Xceed and Absolute (Abbott Vascular, Santa Clara, Calif)-were mounted in elastic silicone tubing, bathed in phosphate buffered saline at 37 degrees +/- 2 degrees C, and examined for fracture after 10 million cycles of chronic deformation. RESULTS: For unstented arteries, the distal SFA/proximal popliteal artery exhibited the greatest axial compression (23%) vs the middle SFA (9%) or popliteal artery (14%) at 90 degrees /90 degrees knee/hip flexion. For stented arteries, the popliteal artery exhibited the most axial compression (11%) vs the middle SFA (3%) or distal SFA/proximal popliteal artery (6%) at 90 degrees /90 degrees knee/hip flexion. Axial compression of the stented popliteal artery at 70 degrees /20 degrees knee/hip flexion was 6% with a deflection angle of 33 degrees . These parameters were used for chronic in vitro fatigue testing, which produced a range of responses in commercially available stents. Chronic 5% axial compression resulted in high rates of fracture of Luminexx (80%) and LifeStent FlexStar (50%), with lower fracture rates for Absolute (3%), Protégé EverFlex (0%), and S.M.A.R.T. Control stents (0%). Chronic 48 degrees bending deformation resulted in high rates of fracture in Protégé EverFlex (100%), S.M.A.R.T. Control (100%), and Luminexx stents (100%), with lower rates in Absolute (3%) and LifeStent FlexStar (0%). CONCLUSION: Nitinol self-expanding stents undergo both axial and bending deformation when implanted into the superficial femoral and popliteal arteries. Commercially available stents exhibit a variable ability to withstand chronic deformation in vitro, and their response is highly dependent on the type of deformation applied.

Lessons learned on how to protect an interventional radiologist against malpractice claims.

Unfortunately, the risk of lawsuit is high for the interventional radiologist, especially for the one who assumes a more active clinical role in the care of patients. The importance of assuming this guardianship role in patient care is paramount to building an active referral base for reasons given in several accompanying articles in this issue. Because of added malpractice risks, it is important to fully understand the risks of this clinical role and how to protect yourself from potential lawsuits. This article discusses in depth steps, which can be taken to lessen the risk of a lawsuit, and steps to help effectively defend against a frivolous claim.

Paperwork for the busy interventionalist: the basic six.

Communication and patient care go hand in hand. Unfortunately, due to time constraints direct verbal communication with health care providers in every instance is not practical; it is also inefficient. Documentation is mandated by the Joint Commission on Accreditation of Healthcare Organizations and hospital bylaws. It reduces ambiguity and actually speeds communication between physician and hospital staff. Standard paperwork is recommended in most cases. Forms for patient admission, history and physical examination, daily patient rounds, preprocedural orders, consent form, discharge summary, and discharge orders allow the busy interventionalist to multitask with reasonable efficiency and fewer mistakes.

Using midlevel providers in interventional radiology.

Developing and implementing clinical services, including consultations, rounds, and clinic, is time-consuming, and for the interventional radiologist this means time away from the interventional laboratory. Using a team approach to providing clinical services is logical, and the midlevel provider is a perfect fit for an interventional radiology team. Midlevel providers can be grouped into two categories, advanced practice nurses (APNs) and physician's assistants (PAs). Under the umbrella of APN are several specialties including the nurse practitioner (NP), clinical nurse specialist (CNS), certified nurse midwife, and certified nurse anesthetist. The midlevel providers that are particularly suited for interventional radiology are the NPs, CNSs, and PAs. This article discusses midlevel providers in-depth including skills, limitations, and expenses.

Establishing surveillance clinics: the road to success.

Interventional radiology interacts with all medical disciplines and historically has not had a patient base of its own. The specialty has depended upon referrals for procedures (often complex) and not referrals for the global management of the disease process or patient. Because of this, when referrers develop catheter-based skills, referrals to interventional radiology drop and competition for primary care physician referrals increase; a double strike. To compete, interventional radiology needs to offer clinical services to the primary care physician. One way to compete is by establishing particular disease surveillance programs. Below we discuss in detail the process of establishing surveillance clinics, which one worked for us, and the expected outcomes of these clinics.

Differentiating pharmacologic agents used in catheter-directed thrombolysis.

The use of catheter-directed thrombolysis is a proven treatment for arterial ischemia, deep vein thrombosis, and severe pulmonary embolism. For arterial ischemia, thrombolysis has resulted in improved amputation-free survival and fewer subsequent surgeries to reestablish blood flow to the ischemic limb. The management of patients with thromboembolic diseases is complex, and the multiple thrombolytic drugs available to choose from compound this complexity. Although some believe the available thrombolytic agents are interchangeable, real biochemical differences exist that may prove otherwise. This article describes these pharmacologic differences and how they may affect the clinical practice of catheter-directed thrombolysis.

Gelatin sponge closure device versus manual compression after peripheral arterial catheterization procedures.

PURPOSE: To evaluate the safety and efficacy of the QuickSeal system, which delivers an over-the-wire extravascular porcine gelatin sponge (nonbovine and noncollagen), compared with manual compression in a single interventional radiology practice. MATERIALS AND METHODS: This single-institution report involves 141 patients undergoing peripheral diagnostic and interventional procedures in a teaching and private-practice setting. A 3:2 device-to-control ratio was used with randomization stratified by type of procedure, interventional or diagnostic. Primary endpoints included time to hemostasis (TTH), time to ambulation (TTA), and rate of major complications. Sheaths were removed in the device group when activated clotting times (ACTs) were < or =300 seconds for patients without glycoprotein (GP) IIb/IIIa platelet inhibitors and < or =250 seconds for patients with GP IIb/IIIa platelet inhibitors. Sheaths were removed in the control group when ACTs were < or =180 seconds. RESULTS: The mean TTH was significantly shorter (P <.001) in the device group (8.2 minutes) than in the control group (14.12 minutes). Mean TTA was shorter in the device group (2.7 hours) than in the control group (7.1 hours), and the time to discharge was shorter in the device group (23.8 hours) than in the control group (43.6 hours). There were no major complications in either group, and the incidences of minor complications were not significantly different. CONCLUSION: The tested device reduced TTH, TTA, and eligibility for hospital discharge while maintaining a safety profile equivalent to that of manual compression in diagnostic and interventional procedures.