Percutaneous Large-Bore Pulmonary Thrombectomy with the FlowTriever Device: Initial Experience in Intermediate-High and High-Risk Patients.

OBJECTIVES: This retrospective cohort study investigates outcomes of patients with intermediate-high and high-risk pulmonary embolism (PE) who were treated with transfemoral mechanical thrombectomy (MT) using the large-bore Inari FlowTriever aspiration catheter system. MATERIAL AND METHODS: Twenty-seven patients (mean age 56.1 ± 15.3 years) treated with MT for PE between 04/2021 and 11/2021 were reviewed. Risk stratification was performed according to European Society of Cardiology (ESC) guidelines. Clinical and hemodynamic characteristics before and after the procedure were compared with the paired Student's t test, and duration of hospital stay was analyzed with the Kaplan-Meier estimator. Procedure-related adverse advents were assessed. RESULTS: Of 27 patients treated, 18 were classified as high risk. Mean right-to-left ventricular ratio on baseline CT was 1.7 ± 0.6. After MT, a statistically significant reduction in mean pulmonary artery pressures from 35.9 ± 9.6 to 26.1 ± 9.0 mmHg (p = 0.002) and heart rates from 109.4 ± 22.5 to 82.8 ± 13.8 beats per minute (p < 0.001) was achieved. Two patients died of prolonged cardiogenic shock. Three patients died of post-interventional complications of which a paradoxical embolism can be considered related to MT. One patient needed short cardiopulmonary resuscitation during the procedure due to clot displacement. Patients with PE as primary driver of clinical instability had a median intensive care unit (ICU) stay of 2 days (0.5-3.5 days). Patients who developed PE as a complication of an underlying medical condition spent 11 days (9.5-12.5 days) in the ICU. CONCLUSION: In this small study population of predominantly high-risk PE patients, large-bore MT without adjunctive thrombolysis was feasible with an acceptable procedure-related complication rate.

Molecular coronary MR imaging of human thrombi using EP-2104R, a fibrin-targeted contrast agent: experimental study in a swine model.

PURPOSE: The aim of this study was to investigate the use of a fibrin-specific contrast agent (EP-2104R, EPIX Pharmaceuticals, Lexington, Massachusetts, USA) for targeted molecular magnetic resonance (MR) imaging of human clot material removed from patients in a model of coronary thrombosis in swine. MATERIALS AND METHODS: Freshly ex vivo engineered clots from human blood and human in situ developed clots removed from patients were delivered into the coronary arteries of nine domestic swine. For MR imaging a navigator-gated, free-breathing, cardiac-triggered 3D inversion recovery black-blood gradient echo sequence was performed prior to clot delivery (baseline), after clot delivery but prior to contrast media administration, and two hours after systemic (i.v.) injection of 4 micromol/kg EP-2104R. MR images were analyzed by two investigators and the contrast-to-noise ratio and Gadolinium (Gd) concentration in the clots were assessed. RESULTS: On baseline images and prior to contrast media application no thrombi were visible. Post contrast administration all 10 coronary emboli (five ex vivo engineered clots and five human clots removed from patients) were selectively visualized as white spots with a mean contrast-to-noise ratio to the blood pool and the surrounding tissue of >12 and a mean Gd concentration of >100 microM. CONCLUSION: Molecular MR imaging using the fibrin-targeted contrast agent EP-2104R allows selective visualization of human clot material in a model of coronary thrombosis in swine.

Thermal laser-induced stenosis of the common bile duct. An alternative model for experimental research.

An experimental model of bile duct stenosis and occlusion in dogs is presented. After percutaneous cholecystostomy of the gallbladder, which had been affixed to the abdominal wall during laparotomy four weeks earlier, a standard 2 mm laser heat probe adapted to an Nd:YAG laser (1,064 nm) was advanced inside the proximal common bile duct in 12 animals, using 6 or 7 F sheaths. The proximal part of the common bile duct was exposed to laser pulses of 6 to 10 Watts for one second. Within 3 to 15 days, total occlusion or severe stenosis of the common bile duct consistently occurred and was verified by follow-up percutaneous cholecystocholangiography. No perforations occurred. Compared with other models, laser thermal damage is an easy and reliable method of producing bile duct stenoses for experimental purposes.

Tissue response of the biliary and digestive system of rabbits after MTBE infusion into the gallbladder.

We evaluated the tissue response of the biliary and digestive system after Methyl-tert-Butyl-Ether (MTBE) gallbladder infusion in 32 rabbits. After laparotomy, MTBE (5-11 ml) was infused into the gallbladder for eight hours. Animals were sacrificed after eight hours or after two months. Control animals received saline solution infusion into the gallbladder. Afterwards the gallbladder, the common bile duct, the liver, the pancreas and the duodenum were examined histologically. All animals receiving MTBE had different degrees of gallbladder necrosis, common bile duct necrosis and necrosis of intrahepatic bile ducts. After two months, scar formation and a hyperplastic cholecystitis were observed. Control animals did not have comparable tissue reactions; only small areas of necrosis in the gallbladder and the common bile duct occurred after eight hours. The gallbladder, common bile duct and liver remained unchanged in those animals which survived two months. Although the results of this animal study cannot be directly transferred to humans, the data suggest that MTBE should be used in gallstone therapy with caution, and that if it is used, a well-controlled follow-up of these patients is necessary.

Vascular tissue ablation by an erbium-YAG laser: a fiber-transmittable pulsed laser in the infrared range.

Vascular tissue ablation by an erbium:YAG laser of 2,940 nm was tested in-vitro with the application of increasing energies from 20 to 80 mJ per pulse. Effective ablation of normal vascular tissue, lipomatous atheromas and calcified plaques was achieved. Penetration depth was considerably diminished in the presence of calcifications. The lasered craters showed smooth surfaces and were regularly shaped. The solid state erbium:YAG, which is transmittable by fluoride fibers, offers theoretical advantages for laser angioplasty.

MR evaluation of stent patency: in vitro test of 22 metallic stents and the possibility of determining their patency by MR angiography.

RATIONALE AND OBJECTIVES: To determine the extent to which visualization of intrastent anatomy in stents of different composition and design is possible by using contrast-enhanced MR angiography. METHODS: Twenty-two MR-compatible stents, most of which had a diameter of 8 mm, were positioned in a phantom filled with aqueous gadolinium solution. Coronal and axial spoiled three-dimensional gradient-echo sequences were performed. Images were acquired with stents positioned at varying angulations to the main magnetic field B0. Profiles orthogonal to the stent axis allowed measurement of artifact sizes independent of window width and center. RESULTS: Oriented along B0, the Cragg, Corvita, Passager, Wallstent, Strecker, Impag, Perflex, and ZA stents allowed visualization of more than 48% of the lumen. The Memotherm, Smart, and Jostent SelfX stents showed a prominent reduction of the inner lumen to below 41%. The lumina of the covered Jostent, Palmaz, Sinus, and Symphony stents were completely obscured. The Impag, Perflex, and Strecker tantalum stents showed growing artifact sizes and a lumen reduction of at least 40% with increasing angulation to B0. CONCLUSIONS. Evaluation of the inner stent lumen by applying contrast-enhanced, three-dimensional gradient-echo sequences is not possible for the majority of stents because of their large artifacts. These depend on the stent type and orientation to B0. Even stents made of nitinol and cobalt alloys only allow qualitative patency assessment but no quantification of stenosis.

Improved in-stent magnetic resonance angiography with high flip angle excitation.

RATIONALE AND OBJECTIVES: To optimize the intraluminal signal intensity of a nitinol stent by performing contrast-enhanced three-dimensional magnetic resonance angiography (CE-MRA) with varying flip angles (FAs). METHODS: Contrast-enhanced magnetic resonance angiography at 1.5 T and FAs of 30 degrees, 100 degrees, and 150 degrees was performed on five sheep with 10 iliac nitinol stents (Memotherm-FLEXX). Maximum-intensity projections (MIPs) and composite images of MIPs were performed and compared. RESULTS: Reconstructed MIPs at an FA of 150 degrees showed a slightly disturbed lumen visibility inside the stent accompanied by low-grade lumen visibility outside the stent and vice versa for an FA of 30 degrees. Composite images of a 30 degrees MIP added to a 150 degrees MIP resulted in improved image quality compared with the standard MIP of a single FA. CONCLUSIONS: Signal loss due to radiofrequency shielding inside nitinol stents imaged by CE-MRA can be reduced by applying high FAs. Composite MIP images allow simultaneous visualization of the lumen inside as well as outside the stent.

Fine caliber cholangioscopy.

The miniaturized diameters of endoscopes (miniendoscopes) allow percutaneous access for endoscopic visualization of the extrahepatic and intrahepatic biliary system. Practical aspects of different miniendoscopes in an experimental model are described. Clinically, fine caliber cholangioscopy is helpful in detection of retained biliary stones. Nevertheless, discrimination of benign and malignant stenosis remains difficult, and simultaneous intervention under endoscopic guidance is compromised by the low steerability of the instruments.

[Imaging of the abdominal wall: combination of tissue-harmonic-imaging and extended field-of-view sonography]. / Ultraschall der Bauchdecke: Kombination von Tissue-Harmonic-Imaging und Panorama-Ultraschall.

PURPOSE: To evaluate the combined use of extended field-of-view sonography and tissue harmonic imaging (THI) for assessment of the abdominal wall. MATERIALS AND METHODS: In 32 patients (25 patients without and 7 patients with abdominal wall pathologies) extended field-of-view sonography of the abdominal wall was performed with and without THI using a 7.5 MHz ultrasound transducer. Images with a scan length of 60 cm were acquired above and below the arcuate line. The images were independently assessed by two observers regarding visibility of the anatomic structures and delineation of pathological changes using a 4-point grading scale. Furthermore, the influence of the extent of the subcutaneous fat on the image quality was assessed. For statistical analysis, kappa coefficients, Fisher"s exact test and a repeated measurement analysis of variance (ANOVA) were applied. RESULTS: In all patients, delineation of the abdominal wall was possible with diagnostic image quality. Abdominal wall pathologies were concurrently diagnosed for extended field-of-view sonography with and without utilization of THI. Image quality was rated better with THI when compared to extended field-of-view B-Mode sonography. In comparison to extended field-of-view B-Mode sonography, the agreement between both readers regarding image quality was markedly improved using extended field-of-view sonography in combination with THI. With increasing thickness of the subcutaneous fat layer, image quality was rated significantly better using THI than B-Mode ultrasound. CONCLUSION: Combined use of extended field-of-view sonography and THI improves image quality and documentation of ultrasound examinations. Especially in obese patients, the use of THI is advantageous. Therefore, abdominal wall ultrasound gains additional value in the preoperative planning.

Transhepatic transcatheter puncture of an occluded biliary intestinal anastomosis for recanalization.

A new technique to recanalize a stenosis following hepaticojejunostomy is described. Transhepatic transcatheter puncture of the jejunum is performed followed by dilatation and electroincision of the new track.

Aspiration catheter for percutaneous thrombectomy: clinical results.

The clinical application of an aspiration thrombectomy system is presented. The system consists of a 7-F Teflon catheter with a rotating coaxial propeller-tipped wire. Thrombectomy was successful in treating occlusion of two femoropopliteal arteries and one hemodialysis implant but was not completely successful in a draining shunt vein. Preliminary results are encouraging; mechanical thrombectomy may offer an alternative to local lysis therapy.

Mechanical revascularization of occluded iliac arteries with use of self-expandable endoprostheses.

Self-expandable endoprostheses were used to restore the vascular lumen following mechanical recanalization of iliac occlusions without preceding thrombolytic therapy. During a 24-month period 48 of 68 occlusions were successfully recanalized. The vessel lumen was restored with the combined use of dilation with an "undersized" balloon and subsequent stent insertion. Early reocclusion occurred in two patients; the patency rate at 6 months was 93.3% (28 of 30 patients). Restenosis prompted repeat intervention in two patients. Percutaneous transluminal angioplasty combined with the use of self-expandable stents is a promising alternative to vascular surgery, although techniques for safely crossing the occluded segment require further improvement.

MR imaging of the knee: three-dimensional volume imaging combined with fast processing.

A new examination protocol for patients with suspected meniscal or hyaline cartilage disorders is presented. Knees were imaged with a fast gradient echo imaging sequence with subsequent three-dimensional transformation. Data were transferred to an image processing system that allows reconstruction in any plane desired. Approximately 200 interactively positioned reconstructions are displayed and reviewed in approximately 10 min. Thirty-five patients with suspected meniscal or hyaline cartilage disorders were examined prospectively. All underwent subsequent arthroscopy. The magnetic resonance (MR) diagnosis showed an accuracy of 91.4% compared with arthroscopic findings. Owing to the short imaging time, the proposed procedure permits screening of knee joint disorders with MR.

Work in progress: percutaneous transhepatic electrocutting of stenoses after hepaticojejunostomy.

A new technique for diathermic incision of stenosed biliary-intestinal anastomoses using a papillotome and high-frequency current is described. The method was applied successfully and without complication in three patients. Despite effective cutting in one patient, multiple residual calculi impacted in the intrahepatic bile ducts necessitated later removal of the stones surgically.

Stent placement on fresh venous thrombosis.

PURPOSE: To report on the efficacy of fixing fresh venous thrombus to the venous wall by stent placement. METHODS: Seven patients underwent stenting to treat acute venous thrombosis. In two patients, the hemodialysis fistula was thrombosed with the thrombus extending into the brachial veins. In three patients, the hemodialysis fistula was patent but massive swelling of the ipsilateral arm was caused by proximal venous thrombosis. Two patients presented with iliac venous thrombosis within stented pelvic veins. Stent placement was preceded by other mechanical thrombectomy methods in all cases. RESULTS: Attachment of thrombus to the venous wall was successful in all cases treated. Acute rethrombosis did not occur. Follow-up patency in dialysis patients was 7.2 +/- 2.1 months. One patient had rethrombosis of the dialysis graft 3 months after primary treatment. Three patients developed restenosis within a mean period of 7.7 months. One shunt remained patent for 10 months with no event of reobstruction during follow-up. In both patients with iliac stent placement, the vein remained patent over a follow-up period of 8 and 12 months respectively. CONCLUSION: Stenting fresh venous thrombus can achieve immediate venous patency. It may be used as an alternative approach when all other percutaneous methods fail. Frequent restenosis within stented veins limits its use to very selected cases.

Successful closure and embolization of a fistula between the pancreatic duct and a pseudocyst using ethibloc.

We successfully achieved complete regression of a pancreatic pseudocyst after Ethibloc embolization of a fistula between the cyst and the pancreatic duct. Previous treatment by percutaneous drainage over 6 weeks had failed. Treatment with a somatostatin analog had not been undertaken.

Late reobstruction in iliac arterial stents: percutaneous treatment.

PURPOSE: To retrospectively analyze in a nonrandomized fashion the efficacy of percutaneous reintervention in obstructed iliac stents. MATERIALS AND METHODS: In 21 symptomatic patients with iliac lesions, 26 reinterventions (16 for stent occlusion and 10 for stent stenosis) were performed. Restenoses were treated with balloon dilation and either atherectomy or stent placement. Reocclusions were treated with atherectomy or aspiration thrombectomy and then recanalization with balloon dilation and selective stent placement. RESULTS: Balloon angioplasty for stent stenosis was effective in all but one patient. Recanalization was successful in 14 of 16 patients with stent occlusion. The mean period of patency after reintervention was 18 months +/- 15. Cumulative stent stenosis patency after reintervention was 87% after 1 year. Stent occlusion patency was 57%. Recurrent stent obstruction occurred in eight of 24 (33%) patients with successful primary interventions. CONCLUSION: Percutaneous reintervention for both stent stenosis and occlusion is feasible with a moderate complication rate and may be attempted before surgery.

Use of a temporary caval filter to assist percutaneous iliocaval thrombectomy: experimental results.

PURPOSE: To test a new filter design that allows coaxial insertion of thrombectomy devices and active clot removal. MATERIALS AND METHODS: A prototype filter system was used in animal experiments. It is a transjugularly inserted coaxial system with a 16-F outer sheath and an inner tube that is covered by a tulip-shaped meshwork with a 22-mm diameter at its inserted end. The inner tube allows insertion of instruments up to 8 F. The filter was developed to assist with percutaneous mechanical thrombectomy in the iliofemoral and caval veins. The filter has been used as an assisting tool in nine sheep and eight pigs. It was combined with an impeller system in nine sheep for caval thrombectomy and with a hydrodynamic catheter for iliac thrombectomy in eight pigs after artificial induction of iliac or caval thrombosis. RESULTS: The filters captured emboli from the intervention in six of nine sheep. The amount of captured emboli was reduced within the filter cone by the impeller instrument in five of six instances. Residual thrombus was removed by closing the filter in five of six sheep. In pigs, the filter captured emboli in three cases during hydrodynamic embolectomy. Pulmonary embolization did not occur with the filter in place. After filter removal, minor pulmonary clot embolization occurred in one case. CONCLUSION: The temporary tulip filter was effective in these animal models in capturing and removing thrombus material that may dislodge from iliocaval veins during mechanical thrombectomy.

Primary stent placement for chronic iliac artery occlusions: follow-up results in 103 patients.

PURPOSE: To report results of primary stent placement for treatment of chronic iliac artery occlusions. MATERIALS AND METHODS: The authors placed 154 primary stents in 103 patients with iliac artery occlusions of at least 3 months duration. Mean length of the occluded segments was 5.1 cm. All patients had symptoms, with claudication or trophic changes. Mean ankle-arm index at rest was 0.48. Follow-up included angiography, Doppler ultrasound, and clinical examination. RESULTS: Ninety-nine patients demonstrated clinical improvement, with relief or improvement of claudication. Complications that required percutaneous or surgical intervention occurred in six patients; minor complications occurred in another six. Embolization occurred in five patients. Primary patency was 87% after 1 year, 83% after 2 years, and 78% after 4 years; secondary patency was 94%, 90%, and 88% at 1 year, 2 years, and 4 years, respectively. CONCLUSION: Primary stent placement should be the treatment of choice in unilateral chronic iliac artery occlusion.

A new motor-driven percutaneous bone biopsy system: technical note.

A new coaxial needle system was designed for percutaneous puncture of osteoclerotic lesions. Driven by a conventional motor unit, the instrument allows safe guidance even where difficult biopsy routes are used, and has been shown to penetrate radiopaque lesions. Preliminary clinical results from 29 patients are presented. The specimens obtained yielded a correct diagnosis in 28 cases. No major complications were observed.