Hans-Dieter Weiss

Current practice of temporary vena cava filter insertion: a multicenter registry.

PURPOSE To evaluate the current practice of temporary vena cava filter placement and its complications. MATERIALS AND METHODS A multicenter registry was conducted from May 1995 until May 1997 using a standardized questionnaire. One hundred eighty-eight patients were evaluated. Patient characteristics, filter indications, filter characteristics, and complications were registered. RESULTS Deep vein thrombosis was proven in 95.2% of the patients. Main filter indication was thrombolysis therapy (53.1%). Average filter time was 5.4 days. An Antheor filter was inserted in 56.4%, a Guenther filter in 26.6%, and a Prolyser filter in 17.%. Transfemoral filter implantation was slightly preferred (54.8%). Four patients died of pulmonary embolism (PE) during filter protection. Major filter problems were filter thrombosis (16%) and filter dislocation (4.8%). When thrombus was found in or at the filter before explantation, additional thrombolysis was performed in 16.7%, additional filter implantation in 10%, and thrombus aspiration in 6.7%; 4.8% of filters were replaced with permanent filters. DISCUSSION Temporary vena cava filters are placed to prevent PE in a defined patient population. Despite their presence, PEs still occur in a small percentage. Problems of filter thrombosis and dislocation have to be solved. CONCLUSION The results of this multicenter registry support the need for innovative filter design, as well as a randomized, prospective study.

Central Venous Access Ports Placed by Interventional Radiologists: Experience with 125 Consecutive Patients

AbstractPurpose: To assess safety and function of central venous port systems implanted percutaneously in the interventional radiology suite. Methods: One hundred and twenty-five consecutive ports in 123 patients were evaluated retrospectively. One hundred and twenty ports were implanted via the subclavian vein. Results: Technical success was 100%. Fourteen patients (11.2%) experienced immediate procedural complications, all minor (pneumothorax 1.6%). During follow-up (4–343 days, mean service period 97.8 days), nine complications occurred, six of which were major. These were three port infections which led to hospitalization and port removal, one chamber penetration through the skin, and two port occlusions. Port removal as a result of complications was performed in six patients. Altogether, 20 complications occurred within a total of 11,056 days of service, which means 1.8 events per 1000 days of service. Conclusion: Percutaneous implantation of central venous port systems is safe and easy to perform. Complication rates of this study compare favorably with those of other radiological and surgical series.

Visualization of magnetic resonance-compatible needles at 1.5 and 0.2 Tesla.

PurposeFor two types of passively visualizable magnetic resonance (MR)-compatible needles, the size of susceptibility artifacts was investigated at 0.2 and 1.5 Tesla (T) and assessed regarding their suitability for needle visualization.MethodsPhantom trials were performed using T1-weighted spin echo (SE), turbospin echo (TSE) and gradient echo (GE) sequences and different angles β between the needles and the main magnetic field (B0).ResultsDepending on the needle angle β and the applied pulse sequence, we found artifact diameters of 0–9.7 mm employing SE, of 1.7–9.4 mm employing TSE, and of 1.4–20.6 mm employing GE at 1.5 T. At 0.2 T, we found artifact diameters of 0–5.7 mm employing SE, of 0–6.3 mm employing TSE, and of 0–11.3 mm employing GE.ConclusionComparing artifact sizes at 1.5T and 0.2 T, low field strength is superior for passive visualization of the needles tested—especially if GE imaging is performed.

Clinical experience with temporary vena caval filters.

PURPOSE To look at the benefits and complications of different vena caval filters inserted prophylactically. Three temporarily implantable caval filter systems were used in 67 patients. MATERIALS AND METHODS Twelve Cook filters (six transjugular, six transfemoral), 11 Angiocor filters (one transjugular, 10 transbrachial), and 44 Antheor filters (three transjugular, four transfemoral, 37 transbrachial) were successfully implanted. In known iliac vein or caval thrombosis, the prophylactic filters were placed during thrombolytic therapy in 46 cases, surgery in 17 cases, thrombosis in pregnancy in three cases, and high-dose heparinization without lysis in one case. RESULTS One patient had a fatal pulmonary embolism during treatment; seven thrombi were detected in the filter. Other complications were caused either by the underlying therapy alone (one fatal outcome of abdominal aorta aneurysmal surgery, two cases of cerebral hemorrhage, two cases of retroperitoneal hematomas, two cases of streptokinase fever reactions, one compartment syndrome, two cases of macrohematuria), by the combination of therapy and caval filter implantation (three cases of groin hematomas, three cases of arm hematomas), or by filter implantation alone (two cases of subclavian vein thrombosis, one catheter infection, one dislocation, one air embolism, one basket rupture). The bleeding complications were related to the aggressive thrombolytic therapy and would have occurred without filter implantation. CONCLUSION Because temporary caval filters have no long-term complications per se, their use seems sensible as long as there are stringent indications, including the presence of iliac vein or caval thrombosis and risk of thrombus mobilization. The Antheor filter system was the most convenient system for implantation.

Efficacy of permanent and retrievable vena cava filters: experimental studies and evaluation of a new device.

Purpose: To evaluate the efficacy of vena cava filters and to compare them with the new TrapEase filter. Methods: Thrombus capture rates of 10 permanent and retrievable vena cava filters were tested in vitro in vertical and horizontal positions with thrombus diameters of 3 and 5 mm (length 30 mm) and tube diameters of 21 and 28 mm. Testing included the new TrapEase filter. Results were compared statistically using Fisher’s exact test (capture rates) and the Kruskal–Wallis test (construction). Results: Best-ranked filters were the Bird’s Nest, the TrapEase and the Simon Nitinol filters. The Tempofilter, the Greenfield and the Keeper filter performed worst. Thrombus capture rates were significantly higher in the vertical position and also higher for large thrombi and in the small cava diameter. Conical filters performed worse than filters with two or more filtration levels. Conclusion: Filters with two or more filtration levels show the highest filtration efficiency in vitro and can be recommended, especially for the critically ill who will probably not tolerate even small emboli. The TrapEase filter is a promising device and should be evaluated clinically.

In Vitro Studies of Temporary Vena Cava Filters

AbstractPurpose: To evaluate the clot trapping capacity of different temporary vena cava filters in a vena cava model. Methods: A vena cava flow model was built using PVC tubing, a hemodialysis membrane and a pulsatile pump. Blood was imitated by a Dextran 40 solution. Five different temporary vena cava filters and two prototypes were tested using human thrombi. The mechanism of clot capture was observed. Results: Decreasing rank order according to decreasing percentage of clots captured for the 21-mm diameter vena cava model was Cook (C) > Angiocor (A) > Cordis (CD) > Antheor (TF-6) > DIL for thrombi with a diameter of 3 mm and A > C > CD > TF-6 > DIL for 5-mm thrombi. In a cava with diameter of 28 mm, decreasing rank order was C > CD = A > TF-6 > DIL and C > CD = A > DIL > TF-6 for 3- and 5-mm thrombi, respectively. Two new prototypes, the TF-8 and TF-10 filters, achieved better results than the TF-6 filter and were in most conditions comparable to the A and CD filters. In most cases, thrombi were trapped between filter and cava wall. Conclusion: The vena cava flow model demonstrates significant differences in rates of clot capture (range 22%–98%) depending on cava diameter, thrombus size, and filter type.

Temporary Vena Cava Filters and Ultrahigh Streptokinase Thrombolysis Therapy: A Clinical Study

AbstractPurpose: To assess the efficacy of temporary vena cava filters in patients undergoing ultrahigh-dose streptokinase thrombolysis for iliocaval thrombosis and to determine therapy success and filter and therapy complications. Methods: Forty-five patients were studied regarding extension and characteristics of thrombosis, duration, success, and complications of thrombolysis therapy, filter type, access route, pulmonary embolisms, and filter complications. Results: Complete recanalization was achieved in 57% of cases. Filters were inserted predominantly via a transbrachial route. One fatal pulmonary embolism (2%) occurred 1 day after starting thrombolysis. No other pulmonary embolism was noted. Other complications were induced by thrombolysis alone (n = 12), thrombolysis and filter (n = 9), and filter alone (n = 11).Conclusion: Fatal pulmonary embolisms as a complication of ultrahigh-dose treatment of pelvic or caval thrombosis can not safely be prevented by the temporary vena cava filters currently available. Filter design needs to be improved.

Initial clinical experience with a new pulsed dye laser device in angioplasty of limb ischemia and shunt fistula obstructions

Selective plaque ablation with laser radiation at 405-530 nm in vitro has been reported. We investigated the possibilities of a new pulsed dye laser device for in vivo recanalization of arteries in ischemic lower limbs and stenoses/occlusions of arterio-venous hemodialysis shunt fistulae. A specially designed 9F or 7F multifiber catheter was used for treatment of 10 patients with lower limb artery obliterations and 11 patients with malfunctioning hemodialysis access fistulae (HAF). The recanalization technical success was 5/5 in the iliac arteries (IA), 4/5 in the superficial femoral arteries (SFA), and 11/11 in the HAF. Early re-occlusions occurred in one SFA and one IA, respectively, caused by very bad run-off. There was one clinically insignificant SFA perforation. Additional balloon angioplasty was considered necessary in 10/16 lesions. Mean ankle-arm index increased from 0.68 to 0.97. With two exceptions all HAF patients were re-integrated in the dialysis program. Pulsed dye laser angioplasty promises to be an effective and fast method for plaque ablation/debulking. The first clinical experience confirms previous in vitro results. In particular laser recanalization may become the method of choice for treatment of rigid HAF obstructions and it seems to be superior to vascular surgery or balloon angioplasty alone.

Neural network approach for computer-assisted interpretation of ultrasound images of the gallbladder

Multi-formatted films of 90 ultrasound examinations of the gallbladder (stones 56 cases, sludge 20 cases, hydrops five cases, normal gallbladder nine cases) have been digitalized and stored in a personal computer. Image data of each examination was processed to extract a 19-dimensional vector that represents the essential diagnostic information of each examination. This vector was evaluated by three different classification algorithms: (1) classical nearest neighbor principle, (2) classical linear discriminant analysis, (3) multilayered backpropagation neural network. The correct classification rate was 64% (58/90) for the nearest neighbor principle, 97% (87/90) for the linear discriminant analysis, and 99% (89/90) for the backpropagation neural network. We conclude that, (1) automated classification of ultrasound images is possible for limited diagnostic problems, (2) a neural network approach can be used successfully for that goal, and (3) the efficiency of the more flexible neural network approach is comparable to large-scale classical methods.

Angiography and angioscopy with injector-applied carbon dioxide

In 10 laboratory swines we investigated an automatic gas injector for angiography and angioscopy that allows the reproducible injection of variable quantities of gas, with variable pressure and injection times. With small volumes of carbon dioxide (CO2; 10–50 cc; 850–1250 mbar application pressure) a column of gas can be created, which facilitates digital subtraction angiography comparable to conventional contrast media (CM) or an angioscopy within a sufficiently bloodless visual field. A total of 93 of 127 angiographies of the abdominal aorta and 49 of 57 angiographies using CO2 were successful. A lack of success was obtained in selective angiographies. The use of injector-controlled CO2 application is an alternative for angiography in patients who are at increased risk using conventional CM. This technique was an unexpectedly excellent method of performing a renal venogram as well as a fast splenoportogram. Petcutaneous transluminal CO2 angioscopy affords a bloodless inspection of the aorta and side branches for a period of several minutes.