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Biomedical subjects

K H Barth

Publications and source records attributed to K H Barth.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Percutaneous management of emboli associated with hot tip laser-assisted angioplasty.

We describe the percutaneous management of emboli that occurred in 3 patients during hot tip laser-assisted angioplasty procedures. One embolus was lysed with direct, local infusion of urokinase using an open-ended guidewire. Another embolus was removed using the transcatheter aspiration technique. The third embolus was partially lysed and then, using a steerable guidewire, displaced placed into a distal side branch. In all 3 cases of embolization, distal blood flow was reestablished using percutaneous techniques, obviating the need for surgical intervention.

Aged↗
PubMedDate not supplied

The use of double guidewires through a single vascular sheath for obtaining profunda femoris arterial access: technical note.

We describe a double guidewire/single vascular sheath technique that facilitates dilatation of stenotic lesions within both the superficial femoral and profunda femoris arteries following a single antegrade common femoral arterial puncture. Such a technique prevents inadvertent loss of vascular access during maneuvers to catheterize the profunda femoris artery or the superficial femoral artery. Angioplasty within the superficial femoral artery with simultaneous safety-wire placement within the profunda femoris artery has been described previously, but we present, in this technical note, successful profunda femoral angioplasty with the safety wire within the superficial femoral artery.

Angioplasty, Balloon↗
PubMedDate not supplied

Evaluation of ferromagnetism and magnetic resonance imaging artifacts of the Strecker tantalum vascular stent.

A woven tantalum vascular stent (Strecker stent) was tested for ferromagnetism at 4.7 T and underwent magnetic resonance imaging (MRI) in vitro and in vivo at 1.5 T to evaluate the production of magnetic susceptibility artifacts. No ferromagnetism was detected. Spin-echo, phase reconstruction, and gradient echo images revealed a low level of susceptibility artifacts both in vitro and in vivo. Our findings demonstrate the feasibility of using MRI to evaluate blood vessels noninvasively following tantalum stent placement.

Animals↗
PubMedDate not supplied

Local intraarterial thrombolysis: in vitro comparison between automatic and manual pulse-spray infusion.

PURPOSE: Manual and automatic pulse-spray infusion techniques are compared in vitro to evaluate the efficacy of thrombolysis and the distribution of urokinase and saline solution within thrombus using a pulse-spray catheter. METHODS: A pulse-spray catheter was introduced into a human thrombus within a stenotic flow model. Automatic and manual pulsed infusion of urokinase and automatic pulsed infusion of saline solution were compared. To quantify the efficacy of thrombolysis, pressure gradients were recorded proximal and distal to the thrombus and during the course of infusion. Distribution of infused urokinase was assessed radiographically. RESULTS: The fastest and most homogeneous dissolution of the thrombus was achieved with automatic pulsed infusion of urokinase, shown by decreasing transthrombotic pressure gradients (p < 0.001, Wilcoxon, matched pairs). Manual pulsed infusion of urokinase or saline solution resulted in inhomogeneous thrombus dissolution and delayed thrombolysis. CONCLUSION: Application of automatic pulse-spray injectors seems beneficial for more effective and homogeneous intraarterial pulse-spray thrombolysis when compared with conventional manual pulsed technique.

Humans↗
PubMedDate not supplied

Embolotherapy for small bowel hemorrhage from metastatic renal cell carcinoma: case report.

Embolization for control of hemorrhage in the small bowel carries a significant risk of bowel infarction. A case is presented where severe gastrointestinal hemorrhage from a hypervascular renal cell carcinoma metastasis to the jejunum was effectively controlled by superselective embolization of mesenteric tumor supply arteries with Gelfoam particles. Adjacent normal mesenteric arteries remained open. It is concluded that in specific instances where direct mesenteric feeders to a tumor can be catheterized, such embolization can be performed safely.

Aged↗
PubMedDate not supplied

Exchange of an obstructed loop nephrostomy catheter: technical note.

Straightening of the distal loop of an obstructed self-retaining "Cope" style nephrostomy catheter may be impossible when the retaining thread is fixed by concretions. We describe a transcatheter technique using an 18 gauge Turner biopsy needle to place a 0.038 inch exchange guidewire for retaining access to the collecting system.

Adult↗
PubMedDate not supplied

Evaluation of a prototype steerable angioscopic laser catheter in a canine model: a feasibility study.

To overcome some of the persisting technical problems related to laser angioplasty, a new catheter was designed and investigated in a canine model. This 5F catheter contained a deflectable tip for steerability, an angioscope, and a laser fiber. Catheter steerability, angioscopic function, and the effects of a 480 nm flash lamp pumped pulsed dye laser on normal canine vessel walls were evaluated. Steering, angioscopic guidance, and application of laser energy were easy and fast to perform in a bloodless vessel segment. Maintaining a condition of bloodlessness at the target site, critical to angioscopic guidance, proved to be the most difficult part in this prototype evaluation. It was noted that the 480 nm pulsed dye laser did not cause macroscopic alterations or perforations to the normal vessel wall. We conclude that a relatively simple deflection mechanism of a small-caliber angioscope provides the kind of aiming ability requisite for precise endovascular therapy. Complete bloodlessness of the area is necessary for both viewing and laser ablation at 480 nm.

Angioplasty, Balloon, Laser-Assisted↗
PubMedDate not supplied

Peripheral angioplasty balloon technology.

Changes in balloon and catheter technology have led to the development of smaller, more flexible, and less traumatic balloon dilatation systems. The physical principles that govern balloon angioplasty and the current status of balloon materials and catheter designs will be reviewed. A compilation of various angioplasty catheters is also summarized.

Angioplasty, Balloon↗
PubMedDate not supplied

Analysis of particle size generated during plaque ablation with a flashlamp pumped pulsed dye laser.

PURPOSE: To examine debris size generated during in vitro plaque ablation by laser energy and estimate the risk of peripheral embolization following laser angioplasty. METHODS: A flashlamp pumped pulsed dye laser of 480-nm wavelength was used to ablate calcified arteriosclerotic plaque, fibrous fatty plaque, and normal aortic wall on samples of human cadaver aortas. Each tissue sample was immersed in saline solution and treated with the same amounts of laser energy transmitted by a 320 microns-diameter glass fiber in direct tissue contact. The debris generated during plaque ablation was then separated from the supernatant and the particles were counted and analyzed for size. RESULTS: Depending on the underlying type of tissue and the setting of laser energy, a wide range of particles with sizes between 5.3 mm2 and 64 microns 2 was found in samples. The largest particles were found after ablation of calcified atherosclerotic plaque, whereas fibrous, fatty plaque and normal aortic wall showed smaller particles and a lesser amount of debris. CONCLUSION: Our study demonstrates that a considerable amount of debris is generated during laser angioplasty at 480 nm and that particle size is sufficient to cause potentially symptomatic embolic occlusions of mid- and small-sized peripheral arteries.

Angioplasty, Laser↗
PubMedDate not supplied

Local intraarterial thrombolysis: in vitro comparison of various infusion catheters.

PURPOSE: Catheters are compared in vitro to evaluate the efficacy of thrombolysis during urokinase infusion within the thrombus. METHODS: Six catheters were introduced individually into human thrombus within a stenotic flow model. Urokinase was infused continuously into the thrombus. To quantify the efficacy of thrombolysis, pressure gradients were recorded proximal and distal to the thrombus and during the course of infusion. Uniformity of lysis was assessed radiographically. RESULTS: The fastest and most homogeneous thrombolysis was achieved with the EDM and the straight-flush catheter, shown by decreasing transthrombotic pressure gradients. All other catheter designs showed less homogeneous and delayed thrombolysis (p </= 0.001, Friedmann-Test, Schaich-Hamerle). There was no significant difference in the efficacy of thrombus dissolution between the EDM and the straight-flush catheter (Wilcoxon, matched pairs, p > 0.7). CONCLUSION: The EDM catheter and the straight flush catheter achieved the most homogeneous and fastest thrombolysis, apparently due to the best urokinase distribution within the thrombus.

Catheterization↗
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The precise determination of vascular lumen and stent diameters: correlation among calibrated angiography, intravascular ultrasound, and pressure-fixed specimens.

PURPOSE: Luminal diameters measured in vivo by calibrated-catheter angiography and by intravascular ultrasound were correlated with those obtained from pressure-fixed histologic cross-sections to determine the accuracy of both methods. METHODS: Angiographic and endosonographic diameter measurements were performed in the center of stents placed in the iliac arteries of 10 miniature pigs and were compared with luminal and stent diameters in postmortem, pressure-fixed, histologic cross-sections from identical locations. RESULTS: Compared with histologic diameters, magnification-corrected angiographic measurements still magnified vascular luminal diameters by 0.7 +/- 0.71 mm (r = 0.41, Pearson; p < 0.003, Wilcoxon, matched pairs), whereas intravascular ultrasound measurements proved to be almost identical to the histologic lumina (r = 0.95, Pearson; p > 0. 5, Wilcoxon, matched pairs). Similarly, stent diameters correlated well between endosonographic and histologic measurements (r = 0.91; p = 0.002), and less well between angiographic and histologic diameters (r = 0.62; p = 0.002). CONCLUSION: Since calibrated angiography still overestimates vascular lumina, endosonography is the preferred technique for accurate in vivo measurements.

Angiography↗
PubMedDate not supplied

Comparison of mechanical deformation properties of metallic stents with use of stress-strain analysis.

PURPOSE: Elastic and plastic deformation properties of the Wallstent, Palmaz stent, and Strecker stent were evaluated quantitatively with an in vitro model simulating forces exerted by an eccentric lesion. MATERIALS AND METHODS: A miniaturized compression testing device was constructed. Stress-strain graphs were obtained for each stent, and the elastic moduli and yield points were calculated. RESULTS: There is a 21-fold range in the elastic modulus among the Wallstent, Palmaz stent, and Strecker stents. The Palmaz stent was the only device to exhibit permanent plastic deformation. The 10-mm Palmaz stent will undergo 15% focal eccentric narrowing at 0.75 atm of pressure; the "standard braid" and "less shortening braid" 10-mm Wallstents at 0.55 and 0.25 atm, respectively; and the 10-mm tantalum Strecker stent at 0.08 atm. Overlapping of stents doubles the stiffness of the Wallstent and the Strecker stent and doubles the yield point of the Palmaz stent. The 4-9 mm Palmaz stent is 30% more resistant to deformation than the larger 8-12-mm version when expanded to identical 8-mm diameters. CONCLUSIONS: The "standard braid" version of the 10-mm Wallstent provides 2.3-fold additional strength for resistant stenoses compared with the "less shortening braid." Overlapping or nesting of stents may permit full expansion should there be incomplete expansion or recoil of a single stent. The 4-9-mm Palmaz stent is preferable from the standpoint of allowing the use of a smaller (7-F instead of 9-F) introducer sheath and also for providing superior resistance to deformation. A purely elastic stent such as the Wallstent is preferable in locations where permanent plastic deformation may occur, such as the thoracic outlet.

Alloys↗
PubMedDate not supplied

Outcome of patients with advanced neoplastic disease receiving vena caval filters.

PURPOSE: The authors examined the appropriateness and outcome of inferior vena caval (IVC) filter placements in patients with advanced malignancies and limited expected survival. PATIENTS AND METHODS: Over a 35-month period, 35 IVC filters were inserted in 34 adult patients with advanced neoplasms. Follow-up was as long as 28 months (mean, 5.2 months). Filter effectiveness, complications, recurrent pulmonary emboli, patient survival, and hospital discharge status were recorded. RESULTS: Twenty-eight patients (82%) were discharged home (n = 21) or to nursing facilities (n = 7) between 1 and 193 days (mean, 23 days) after filter insertion. Six patient (18%) died during hospitalization 1-95 days after filter insertion. The overall mean survival was 6.6 months; for patients with stage III and IV tumors mean survival was 8.0 and 5.5 months, respectively. Even among patients with stage IV disease, 59% survived longer than 3 months. There were no complications related to filter insertion and no clinical evidence of recurrent pulmonary emboli. In 14% of patients, filters enabled invasive therapeutic and palliative procedures to be performed. CONCLUSION: The presence of advanced neoplastic disease by itself should not be a deterrent to insertion of IVC filters, as most patients survived well beyond initial hospitalization.

Adult↗
PubMedDate not supplied

Long term follow-up of transcatheter embolization with autologous clot, oxycel and gelfoam in domestic swine.

Transcatheter embolization of the distal gastrosplenic artery as well as the distal right renal artery or one of its bifurcational branches was performed in 9 domestic swine. The animals were embolized with fresh autologous clot, oxycel or gelfoam in groups of 3. The embolic material was opacified with tantalum in several animals. At 4 months, none of the initial occlusions was sustained and recanalization without residuals was found in the left gastroepipolic artery with only one minor exception. Organized thrombi as sole vascular residuals regardless of embolic substance were found in both the terminal splenic artery as well as in the right renal artery distribution in various degrees together with infarcts in both organs. No trace of either oxycel or gelfoam remained, nor tissue reaction against either material. All 3 agents are therefore regarded equivalent in their long term effects and are not suitable for permanent vascular occlusion.

Animals↗
PubMedDate not supplied

A simple method to measure mesenteric arteriovenous shunt flow during arteriography.

A quantitative method for external detection of mesenteric arteriovenous shunts was developed. 99mTc-Human Serum Albumin Microspheres (15--30 microns) were injected into the superior mesenteric artery of dogs through an angiographic catheter, followed by external scintillation counting of the liver activity, which represented the shunted spheres. Thereafter, 99mTc-sulfur colloid was injected identically and the liver activity counted again. The liver net count after sulfur colloid represented a 100% shunt, when a correction factor for the actual liver uptake was applied. The a shunt rate was calculated. Eleven animal studies were performed and shunt rates similar to previous in vitro determinations were obtained. This method is suitable for clinical investigation and can conveniently be applied to mesenteric arteriography.

Animals↗