[Angiography and pressure measurement with a coaxial sliding guidewire: follow-up after renal angioplasty].
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Angioplasty, Balloon↗
Biomedical subjects
T Schmitz-Rode
Publications and source records attributed to T Schmitz-Rode.
[Angiography via an aerosol spray. A new technic for arterial imaging with CO2 under DSA conditions].
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Aerosols↗
Self-expandable spindle for transcatheter vascular occlusion: in vivo experiments. Work in progress.
A mechanical vascular occluder was studied in eight pigs to test its efficacy in arteries of different diameters, stability over time, and safety in placement. The main component is a self-expandable spindle made of tubular stainless steel mesh. Simple steel spindles, double spindles, and Dacron-core spindles were placed in the common carotid artery, main renal artery, renal artery branches, and infrarenal aorta. Follow-up arteriograms were obtained immediately, 30-60 minutes, and (except for aortic spindles) 7 days after deployment. The left common carotid artery was occluded in all pigs, regardless of spindle type. In the main renal artery and its branches, simple steel spindles did not achieve complete occlusion. Double and Dacron-core spindles produced immediate occlusion without recanalization on the 1-week follow-up arteriogram, except for one spindle with an incomplete Dacron core and two spindles that did not completely fill the arterial lumen. Two Dacron-core spindles achieved immediate complete occlusion of the infrarenal aorta. No migration was seen with any spindle.
Animals↗
Percutaneous embolectomy: in vitro investigations of the self-expanding tulip sheath.
A self-expanding sheath with a tulip-shaped distal end was designed for performance of percutaneous embolectomy. Its ability to retrieve clots was tested in an in vitro flow model; results were compared with those obtained with a conventional 10-F sheath. Simulated embolectomy of clots weighing 0.1-1.5 g was performed with a 0.75-mL Fogarty balloon on a 4-F catheter. The clot material that embolized distally during the procedure was sampled and quantified. No effective embolectomy was performed via a conventional sheath. With the tulip sheath, however, complete clot removal was achieved unless the clot size exceeded the tulip volume. On the basis of results of in vitro testing, the tulip design is promising for use in several applications during percutaneous interventions.
Catheterization↗
[CO2 angiography: measuring blood flow with injected gas bubbles].
The use of CO2 gas as a contrast medium for visualizing blood vessels has been considerably facilitated by the development of a gas metering device for mechanical injection of CO2. The present paper describes the possibility of using CO2 not only for visualizing blood vessel morphology, but also for the diagnostic evaluation of the haemodynamics within the vessels. For this reason in vitro experiments with an artery simulation model were undertaken to examine the behaviour of injected gas bubbles. The information thus obtained was then translated to animal experiments.
Angiography, Digital Subtraction↗
Comparative examination of various rectal tubes and contrast media for the reduction of intussusceptions.
The hydrodynamic influence of different rectal tube sizes, contrast media, and heights of the fluid column on hydrostatic reduction of intussusception was analyzed in vitro. Enemas were performed in dead rabbits to compare the filling speed of bowel with a liquid and a gaseous contrast medium. For hydrostatic reduction, tubing and rectal tube with a large caliber and a low viscosity contrast medium achieved a higher filling speed of colon and are expected to provide a higher force of reduction on the intussusceptum. A rectal tube with a large caliber can be more useful than an increase of the column height. Filling bowel with carbon dioxide was approximately 7 times faster than with meglumine sodium diatrizoate. Theoretical considerations allow the hypothesis that a gaseous medium provides a faster and steadier reduction than a liquid.
Animals↗
US-assisted aspiration thrombectomy: in vitro investigations.
The authors describe the use of a new ultrasound (US)-aspiration thrombectomy technique. An oscillating US probe was inserted into a thin-walled, large-bore aspiration catheter. Experiments tested the ability of the new device and other catheter combinations to remove clot material from a Petri dish, as well as from small and large vessel models made of silicone and glass tubes, respectively. Results of the experiments demonstrated that an oscillating 1.0-mm US probe inserted into an aspiration catheter (7-9 F in diameter) promoted clot fragmentation and allowed continuous aspiration of thrombi of any size. When compared with simple large-bore catheter aspiration and with mechanical fragmentation by means of a US probe within a catheter that was flushed to cool the probe, US-assisted aspiration thrombectomy demonstrated significantly better results for percutaneous transcatheter removal of fresh thrombi.
Equipment Design↗
New device for percutaneous fragmentation of pulmonary emboli.
A new catheter system was designed for percutaneous fragmentation of large pulmonary emboli. The device consists of an impeller rotating at high speed at the center of a self-expandable basket at the tip of a 7-F catheter. The highly flexible catheter was able to reach all tested embolus sites in a glass model of the pulmonary arterial tree. Embolus fragmentation was quick and thorough. Particles in the effluent larger than 10 microns accounted for only about 9% of the treated embolus weight. Wall contact with the rotating impeller was not observed. The impeller-basket catheter promises to be a useful tool for percutaneous treatment of acute pulmonary embolism.
Catheterization↗
Percutaneous mechanical thrombolysis. A comparative study of various rotational catheter systems.
In vitro fragmentation of thrombi was performed with the Kensey catheter, the Bildsoe catheter, the Günther aspiration catheter, and two modified aspiration catheters in a model circuit under femoral and pulmonary artery flow conditions. In the femoral artery model all tested catheters worked sufficiently: particles larger than 1000 microns in the effluent comprised only 1.27% +/- 0.46% of the initial thrombus weight. In the treatment of larger thrombi (pulmonary artery model), the action of rotational aspiration devices, and in particular of the Bildsoe catheter, was limited: fibrin filaments winding around the rotating tip led to catheter obstruction. The Kensey catheter yielded best results in the fragmentation of large thrombi.
Catheterization, Peripheral↗
The geometry of the aortic root in health, at valve disease and after valve replacement.
For the design of aortic valve prostheses with a separation-free flow field and minimum pressure drop the geometry of the aortic root is of high importance, since an appropriate adjustment of the prostheses to the surrounding geometry could largely reduce the risk of thromboembolic complications. For the investigation of the geometry of the aortic root 604 angiographic films out of a total stock of 15,000 of the Medical Clinic I were evaluated. The film material was preclassified into five clinical categories according to the patient's data. For each category characteristic geometries could be derived in non-dimensional form.
Aorta↗
Functional properties of the Kensey arterial recanalization catheter. In vitro investigations.
The properties of the Kensey catheter (Cordis Corp., Miami Lakes, FL), a new rotational device for recanalization of arterial occlusions, were studied in vitro. There was no effective centering of the catheter tip in the vessel and no measurable dilatation of the vessel lumen during rotation of the catheter tip. Flow studies confirmed recirculation and repeated exposure of particles at the catheter tip. The vortex induced by the rotating cam disappeared in stenotic segments. The maximum size of the pulverized specimen material was 20 microns for the normal arterial wall, 90 microns for the calcified and atheromatous plaque, and 900 microns for the fresh venous thrombus. For plaque material, an additional reduction of large particles to 30 microns was seen with a decrease in force and an increase in rotation speed. The size of thrombus particles decreased with an increase of rotation speed and the duration of treatment.
Arterial Occlusive Diseases↗
MRI-guided biopsy of bone in a hybrid system.
This is a report of our experience with percutaneous, MRI-guided biopsies in 25 patients with skeletal lesions using a 1.5-T MR hybrid system. Twenty-five consecutive patients with skeletal lesions were referred for MRI-guided biopsy. Biopsies were performed with a 1.5-T Philips Gyroscan (Philips Medical Systems, Best, The Netherlands) combined with a c-arm fluoroscopy. Specimens were obtained percutaneously either with a 14- or 18-gauge "side-slit" type of biopsy needle (n = 10 skeletal lesions that had penetrated through the cortex), or using a prototype coaxial drill system powered either by hand or an optional motor (n = 15 skeletal lesions still covered with cortical bone). All but two biopsies could be completed within the MR unit. For one patient, who required a transpedicular approach to a lumbar vertebra, and for one child, who required general anesthesia, we decided to switch to CT guidance. In 19 of the 25 cases (17 of the 23 cases performed in MR), the sample was sufficient and the histopathologic diagnosis was confirmed. Three patients had an inadequate sample, and three others had adequate samples but inaccurate results. No procedural complications occurred. Percutaneous biopsy of skeletal lesions performed under MRI-guidance was found to be safe and reasonably accurate. There were no procedural complications in our small series. MRI may be used as an alternative to CT, but its role vis-à-vis CT has yet to be ascertained.
Biopsy, Needle↗
New device for wire and catheter capturing: in vivo experiments and first clinical experience.
PURPOSE: A new self-expanding tulip sheath was tested for percutaneous wife capturing in a femoro-femoral pull-through maneuver. METHODS: In six sheep, a self-expanding tulip sheath was introduced into the right iliac artery. A 5 Fr catheter and an 0.035-inch guidewire were guided into the iliac artery from a left femoral approach. Thirty-six tests were performed to guide the guidewire out of the right groin using the tulip sheath, by catching the catheter first in 18 tests and just by catching the guidewire in the other 18. As a control, six tests were performed using a conventional sheath. We performed one clinical arterial application. RESULTS: There was prompt capture of the wire in 35 of 36 tests using a self-expanding sheath. Five of six tests using a conventional sheath failed. The clinical application of the tulip principle was successful. CONCLUSION: Using the self-expanding tulip sheath to facilitate wire capture during pull-through maneuvers, even in difficult situations, is promising.
Aortic Dissection↗
Experimental impeller fragmentation of iliocaval thrombosis under tulip filter protection: preliminary results.
PURPOSE: To assess the efficacy of catheter fragmentation of massive caval thrombosis and of filter protection against procedure-related pulmonary embolism. METHODS: In 10 sheep, a self-expanding tulip-shaped filter made from Wallstent mesh (diameter 25 mm) was introduced from the right jugular approach into the proximal inferior vena cava. Experimentally induced massive iliocaval thrombosis was fragmented by an impeller catheter (expanded diameter 14 mm), which was advanced coaxially through the sheath of the expanded filter. Post-procedural cavography and pulmonary angiography were performed to document the extent of caval recanalization and pulmonary embolism. RESULTS: In all cases, impeller fragmentation cleared the inferior vena cava and the iliac veins of thrombi completely. Fragments washed downstream were trapped in the filter. In two of the first cases, parts of the clots caused pulmonary embolism before the filter was in place. Further events were avoided by a modification of the experimental setup. Except for some small peripheral perfusion defects in two cases, pulmonary angiograms did not show any incidence of pulmonary embolism. CONCLUSION: Our preliminary results suggest that impeller fragmentation of iliocaval thrombi under tulip filter protection is effective and does not cause significant pulmonary embolism.
Animals↗
Percutaneous fragmentation of pulmonary emboli in dogs with the impeller-basket catheter.
A new catheter system for rapid percutaneous fragmentation of pulmonary emboli was tested in nine dogs. The system consisted of a high-speed rotating impeller, placed within the center of a self-expandable basket. Preformed radiopaque emboli were introduced via the right external jugular vein. In nine tests in five dogs, a single embolus was launched after the right pulmonary artery had been balloon occluded and the impeller-basket catheter had been positioned into the left pulmonary artery. Seven of nine emboli were completely fragmented, each within less than 10 s. In two tests, performed in two different dogs, the catheter was positioned after complete embolization of the left pulmonary artery. In both cases, the central pulmonary arteries could be fully, and the segmental arteries partly, recanalized. Mobility of the system within the pulmonary arteries was limited. There was no evidence of wall damage at the rotation site of the impeller. Free serum hemoglobin did not increase after treatment. We conclude that the device can be safely operated in the left pulmonary artery system of dogs. It causes no significant hemolysis, and is able to accomplish rapid recanalization of the central arteries. Due to limited steerability, occluded side branches cannot be treated consistently.
Animals↗
Percutaneous thrombectomy of the acutely thrombosed dialysis graft: in vitro evaluation of four devices.
Percutaneous recanalization of completely thrombosed hemodialysis grafts was simulated in a flow model. Thrombus removal was performed by 1) a Trac-Wright catheter; 2) an ultrasound-driven, oscillating probe aspiration thrombectomy (US-OAT) device; 3) an electric motor-driven oscillating probe aspiration thrombectomy (EM-OAT) device; and 4) a rotating spiral aspiration thrombectomy (RAT) device. All devices were able to restore a continuous lumen of the shunt model within 1-5 min, but residual layers of wall-adherent thrombi remained attached, particularly to the inner curvature of the shunt loop. Clot removal rate was 95% for the Trac-Wright catheter, 73% for the US-OAT device, 68% for the EM-OAT device (straight tip catheter), 88% for the EM-OAT device (angulated tip catheter), and 51% for the RAT device. Effluent particle rates for particles > 100 microns were 3.6% for the Trac-Wright catheter, 0.6% for US-OAT, and less than 0.1% for the other devices. Compared with the Trac-Wright catheter, the balance of clot-removing efficiency and creation of effluent particles favored the electric oscillating device with the angulated tip catheter, which had a slightly reduced, but still efficient, clot-removing capability and produced almost no effluent particles.
Acute Disease↗
New "mesh basket" for percutaneous removal of wall-adherent thrombi in dialysis shunts.
A new basket, developed for percutaneous removal of wall-adherent thrombi, was tested in model thrombosed hemodialysis shunts and clinically in two polytetrafluoroethylene grafts and one Brescia-Cimino shunt after recanalization by aspiration thrombectomy. The residual wall-adherent thrombus was removed by one or two passes with the mesh basket. The occlusion material was firmly captured within the mesh and was removed through an 8F sheath without hardly any material being sheared off from the basket. The device adapts well even to tortuous vessel segments and exerts a gentle brush effect. It may prove to be a valuable adjunct to aspiration thrombectomy or to balloon catheter embolectomy.
Animals↗
CO2 spray mini-injector for digital subtraction angiography versus PC-controlled injection system: experiments in dogs.
A personal computer (PC)-controlled CO2 injector (consisting of a pneumatic unit, electric/electronic system, and calculator) and a spray mini-injector (consisting of a CO2 spray can and a dosage chamber) were used in 10 dogs to determine their efficacy regarding imaging quality and ease of handling. CO2 was injected into the abdominal aorta, renal artery, and femoral artery. The vessel diameter was determined on each CO2 arteriogram and compared with that determined on a reference arteriogram obtained using an iodinated contrast agent. The filling ratio (CO2/iodine) was calculated for each set of injection parameters. Both injection systems provided good visualization (filling ratio > 0.9) of large and small arteries within a range of injection parameters. In terms of practicality, the spray mini-injector is more appealing, because it is easier to handle and does not require any preparation.
Aerosols↗