Re: Approaches to the superior calix: renal displacement technique and review of options.
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Humans↗
Biomedical subjects
K H Barth
Publications and source records attributed to K H Barth.
Optimization of gradient-echo imaging parameters for intracaval filters and trapped thromboemboli.
Flow-phantom magnetic resonance (MR) gradient-echo (GRE) imaging at 1.5 T was performed on a titanium Greenfield filter containing trapped blood clots with a high concentration of either deoxyhemoglobin (DHb) or methemoglobin (MHb), simulating acute and older thromboemboli, respectively. Flip angle, repetition time (TR), and echo time (TE) were varied, and a contrast-to-noise ratio between trapped clots and flowing fluid (clot-flow contrast) was determined for each set of imaging parameters. Use of very low flip angles (less than or equal to 10 degrees) rendered MHb clots indistinguishable from flowing fluid. In general, DHb clots displayed greater clot-flow contrast than MHb clots regardless of flip angle. With increasing TE values, T2* effect was observed with MHb clots, and magnetic susceptibility artifacts increased. Overall, optimum clot-flow contrast for imaging of both DHb and MHb clots was achieved with a flip angle of 45 degrees-60 degrees, a TR of 50 msec, and the shortest TE possible. Using GRE parameters similar to the optimum parameters determined in vitro, the authors imaged four patients with nickel-titanium Simon filters and one dog with a titanium Greenfield filter. MR imaging was successful in demonstrating filter location, caval patency, and the presence and extent of intraluminal thrombus.
Adult↗
Self-contained, coaxial delivery system for intraarterial infusion of thrombolytic agents.
To facilitate continued direct intrathrombus infusion of a thrombolytic agent and yet minimize catheter exchanges and manipulations, the authors developed a simple, self-contained delivery system. It involves the use of supplies available in most angiographic suites. The system has been used in 44 patients; there have been no infectious complications, and it has been well tolerated by the patients.
Fibrinolytic Agents↗
Flexible tantalum stents implanted in aortas and iliac arteries: effects in normal canines.
Vascular endoprostheses made of knitted tantalum wire and expanded over angioplasty balloons were placed into aortas or iliac arteries of 14 normal dogs. Twelve stents were placed into the infrarenal abdominal aorta and two stents in the left common iliac arteries by the left carotid artery approach. To firmly expand the stent against the vascular wall, nominal stent sizes 0.5-1.0 mm larger than the measured arterial diameter were required. Arteriography performed at specified follow-up intervals showed no evidence of thrombi or emboli; all side branches (lumbar arteries) covered by the stents remained patent. Vascular diameter decreased minimally at 8 and 26 weeks, associated with histopathologic evidence of neointimal buildup. This buildup was highest at 8 weeks (mean, 313 microns) and was slightly less at 26 weeks (mean, 223 microns). Almost complete coverage by endothelium was seen as early as 3 weeks. It is concluded that the flexible tantalum wire stents are well tolerated by the arterial wall and become quickly endothelialized. No excessive neointimal buildup was observed during the 6-month study.
Animals↗
Expandable tubular stents for treatment of arterial occlusive diseases: experimental and clinical results. Work in progress.
The balloon-expandable vascular prosthesis consists of a flexible, knitted tantalum wire mesh tube. To demonstrate its pliability, this prosthesis was tested experimentally in 10 mongrel dogs by implanting it into the proximal femoral arteries. The maximum follow-up time was 1 year. On the basis of the experimental results, in which there was no relevant stenosis, occlusion, or migration of the vascular prosthesis, nine patients were treated: one with iliac artery occlusive disease and eight with superficial femoral artery (SFA) occlusive disease (four reocclusions after angioplasty and four unsatisfactory primary angioplasty results). One SFA lesion was treated with the crossover method from the contralateral side. All implants remained patent without hemodynamically significant stenoses, with the longest observation time being 6 months. Flexible, expandable vascular prostheses are promising adjuncts to angioplasty.
Aged↗
Percutaneous biliary drainage for high obstruction.
PBD is the preferred route of palliative drainage for patients with high biliary obstruction. The frequency of bifurcational obstruction in this setting requires familiarity with drainages from both the right and the left transhepatic approach. The preferred right transhepatic approach is fluoroscopically guided; on the left, ultrasonography is the guidance of choice. Large caliber drainage catheters are required, and dilatation of the necessary transhepatic tracts is extremely painful unless adequate inhalation anesthesia or, preferably, epidural anesthesia, is provided. Long-term biliary drainage requires a choice between internal-external external drainage catheters and endoprostheses that is made by considering the patient's life expectancy and his or her adjustment to a stent extending to the outside. The feasibility of corrective procedures if an internal-external drainage catheter or an endoprosthesis becomes blocked needs to be considered before definitive placement. The interventional radiologist becomes intimately involved in the follow-up care of patients and frequently has to direct appropriate patient evaluation. Familiarity with antibiotic regimens is important.
Cholangiography↗
Tantalum vascular stents: in vivo evaluation with MR imaging.
Magnetic resonance (MR) imaging at 1.5 T was performed on tantalum vascular stents placed in the aortas of six dogs. The stents produced no significant artifact and allowed for clear depiction of the aortic lumina as flow-void zones with spin-echo imaging and as high-signal areas with gradient-echo imaging. The MR findings correlated with the angiographic studies of the stented vessels. These results demonstrate the feasibility of MR imaging as a noninvasive means of evaluating vessel patency in the presence of tantalum vascular stents.
Animals↗
Hepatic artery model for evaluating the distribution of intraarterial chemotherapy infusion: nonpulsed versus pulsed infusions.
The effect of a commercially available pulsatile slow-infusion system on the degree of infusate mixing and distribution was assessed in a life-size glass model of the hepatic arterial system. The authors determined, both visually and quantitatively, the mixing homogeneity of a low-flow infusion (1.4 mL/min) of red dye through a side-hole catheter (2.5 F outer diameter) into pulsatile flow (300 mL/min) of a fluid with the same viscosity as blood. When comparing nonpulsed versus pulsed infusion techniques, the authors found that the pulsatile infusion system did not significantly improve the inhomogeneity of dye distribution in the 16 hepatic arterial branches. The results of this in vitro study suggest that a pulsatile infusion system that uses low pulse velocities without regard for cardiac cycle is less than optimal and does not significantly improve drug mixing at the standard slow infusion rates. Moreover, as potential new intraarterial delivery systems are developed to improve drug mixing, in vitro models may be the most useful means of initially evaluating their efficacy.
Hepatic Artery↗
Double-guide-wire access through a single 6-F vascular sheath.
Three techniques are described that employ double-guide-wire access through a single vascular sheath in the common femoral artery. One technique provides arterial side branch protection during balloon angioplasty of stenotic vascular branch points. Another maintains guide wire access within a dilated renal artery while postangioplasty aortography is performed. A third technique achieves superficial femoral artery access during antegrade femoral artery puncture.
Aged↗
Anatomic relationship between the common femoral artery and vein: CT evaluation and clinical significance.
Knowledge of the anatomy of the common femoral artery (CFA) and common femoral vein (CFV) is important to minimize complications associated with transfemoral angiographic procedures. The authors assessed variations in the relationship between the CFA and the adjacent CFV by reviewing the inguinal region of 100 computed tomographic scans of the pelvis (200 vessel pairs). In 65% of the vessel pairs studied, a portion of the CFA overlapped the CFV in an anteroposterior plane. In addition, more than 25% of the artery overlapped the vein in 8% of the vessel pairs. This variation in anatomic relationship between the CFA and CFV is clinically significant, since a femoral vein puncture can be associated with simultaneous passage of the entry needle through the artery and thus formation of an arteriovenous fistula.
Adolescent↗
Vena caval filter splaying: potential complication of use of the titanium Greenfield filter.
Significant structural and mechanical differences exist between the titanium and stainless steel versions of the Greenfield filter (GF). The titanium GF has a longer leg length (49 mm vs 43 mm), a greater span (38.5 mm vs 28.0 mm), and a larger hook angle (41 degrees vs 23.5 degrees). In vitro tests demonstrated approximately sevenfold greater filter length shortening (a measure of filter splaying) for the titanium GF in response to a given applied load. These differences resulted in marked filter splaying and inferior vena cava (IVC) perforation in three patients in whom a titanium GF had been inserted. The aorta was penetrated by a filter leg in one patient, and abdominal or back pain was present in all three patients. In vitro tests involving thrombosis within a latex balloon revealed that the titanium GF, but not the stainless steel GF, remained splayed even in the face of clot retraction. Design modifications, possibly using shorter, thicker filter legs and using reduced hook angles, should be made in the titanium GF to decrease the risk of filter splaying and IVC perforation before widespread use of this device.
Adult↗
Superselective gelfoam embolotherapy using a highly visible small caliber catheter.
A new, highly visible and flexible 3F catheter has become available for superselective catheterization and embolization. We describe the first reported series of cases in which this catheter was used for superselective Gelfoam embolization of bleeding visceral arteries.
Adult↗
Mixing problems of low flow hepatic artery infusion. Improvement with small caliber double lumen balloon catheters.
The problem of inhomogeneous mixing encountered during hepatic artery (HA) chemotherapy infusion was assessed and a practical solution examined. A glass model of the human HA distribution was used to determine mixing homogeneity of low flow (1.4 mL/minute) dye infusion into pulsatile flow (280-300 mL/minute) of a fluid isoviscous to blood. Dye concentration in each of 16 HA branches was determined by photospectrometry. Dye infusion was carried out through 2-2.5F double lumen end hole or proximal side hole balloon catheters without balloon inflation, with balloon inflation maintaining full HA flow, and with the balloon inflated so that HA flow was reduced by 50%. The measurements taken without balloon inflation showed gross inhomogeneity of dye concentration in various branches. The inhomogeneity was not improved during balloon inflation as long as full HA flow was maintained. After balloon inflation reduced HA flow by 50%, dye mixing was improved significantly, with infusion through side hole catheters (alpha = .002) but not significantly (alpha = .2) with infusion through end hold catheters. This investigation suggests that the proposed technique might be useful for clinical application and deserves further evaluation in an in vivo system.
Antineoplastic Agents↗
Complication associated with a new plastic-coated guidewire.
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Angiography↗
Extracorporeal shockwave lithotripsy: role of the radiologist.
Extracorporeal shockwave lithotripsy (ESWL) is a new noninvasive treatment modality for urinary calculi. ESWL may be applied to the majority of patients requiring stone removal and is expected to replace, to a large degree, percutaneous stone removal (PSR), now practiced jointly by interventional radiologists and endourologists in most institutions. In a number of cases, ESWL and PSR will be complementary procedures. Technically, ESWL can be considered a radiologic procedure; thus far, radiologists are not participating in its use. In the authors' opinion, ESWL should be a combined urologic radiologic procedure analogous to PSR; this will allow the most rational and effective treatment.
Humans↗
Iatrogenic sclerosing cholangitis following hepatic arterial chemotherapy infusion.
A case of common hepatic duct stricture secondary to hepatic artery chemotherapy infusion is described. CT and endoscopic retrograde cholangiopancreatography (ERCP) may be used in concert to differentiate this entity from other causes of jaundice--namely, hepatic replacement by tumor, porta hepatis adenopathy, and chemotherapy hepatotoxicity.
Adenocarcinoma↗
Interventional radiology.
Interventional radiology is defined as a radiologic subspecialty and the services provided are tabulated in this article; those services relevant to internists are described in greater detail. This article is intended as a survey, and the authors encourage the reader to consult the references provided for a more in-depth review.
Abscess↗