Placement of a spring filter during interventional treatment of deep venous thrombosis to reduce the risk of pulmonary embolism.

PURPOSE: To assess the efficacy of the Spring filter during interventional treatment of deep venous thrombosis in vivo. MATERIAL AND METHODS: A model of inferior vena cava thrombosis was used. Part I: The thrombus was treated by the pulse-spray technique (PT) (urokinase 250,000 IU; n=7) or a rotatory basket catheter, Thrombolizer (MT) (activated with compressed air at 7 atm; n=5). Part II: Following placement of a Spring filter, the animal underwent PT (n=5) or MT (n=5). Based on the results of part I, the treatment protocol was modified (PT, urokinase 500,000 IU; MT, compressed air at 8 atm). Embolus volumes trapped by the filter and found in the lungs were calculated and the filtering efficacy quantified. RESULTS: Part I: Pulmonary emboli (1 to 4 mm in diameter) were observed in 3 animals in the PT group and 1 animal in the MT group, respectively. Median reduction in thrombus volume was 21% and 4% by PT and MT, respectively. Part II: In the PT group, 58% and 100% of the total embolus load was trapped in 2 animals, while the filter failed to trap emboli (1 to 1.5 mm in diameter) in 1 animal. In the remaining 2 animals, no embolus was found trapped by the filter or in the lungs. In the MT group, 55 97% (median 83%) of the embolus load was trapped. Emboli found in the lungs did not exceed 4 mm in diameter. CONCLUSION: Preceding interventional treatment of venous thrombosis with placement of the Spring filter reduced the embolic burden on the lungs.

In vivo evaluation of the adjustable temporary venous spring filter and the RF02 temporary filter: comparative study.

RATIONALE AND OBJECTIVES: The authors performed this study to compare the in vivo efficacies of the temporary venous spring filter and the RF02 filter in an animal model. MATERIALS AND METHODS: Either the spring filter or the RF02 filter was placed in the inferior vena cava of 10 pigs each, and two clots (5 x 20 mm) were funneled into the filters at 1-hour intervals. The second clots were funneled without removing the first clots captured by the filters. Clot-trapping ability, caval occlusion associated with the clot-trapping procedure, arterial blood gas concentrations, and changes in arterial and iliac venous pressures were evaluated. RESULTS: Placement of the RF02 filter caused elevation of iliac venous pressure with a maximum of 2.2 mm Hg (median) (n = 13, P = .003). Placement of the spring filter parallel to venous flow enabled capture of 90% (nine of 10) and 100% (six of six) of the first and second clots, respectively. The RF02 filter captured clots consistently. The difference between filters was not statistically significant. Both filters equally contributed to elevation of iliac venous pressure (median, 9.3 and 7.2 mm Hg [n = 9] with the spring filter and RF02 filter, respectively). Caval occlusion occurred in 17% (one of six) and 67% (six of nine) of animals after two clots were trapped in the spring filter and RF02 filter, respectively (P = .06). Other parameters were not influenced by the clot-trapping procedure. CONCLUSION: Although a larger version should be developed and better stability of the filter is needed, the spring filter proved to be an efficient filtering device and had a lower rate of caval occlusion compared with the RF02 filter.

In vitro function of an adjustable temporary venous spring filter: comparison with the temporary RF02 filter and the permanent Greenfield vena cava filter.

RATIONALE AND OBJECTIVES: The authors compared in vitro function of a temporary venous spring filter with that of a temporary RF02 filter and a permanent Greenfield filter. MATERIALS AND METHODS: All three types of filters were placed in thin polyethylene tubes (diameters, 10.0-18.0 mm). Physiologic saline was substituted for flowing blood, and blood clots of three sizes (6 x 10 mm, 6 x 20 mm, 9 x 20 mm) were funneled to the filters. Clot-trapping ability of each filter and elevation of intraluminal pressure after clot trapping were assessed for each tube size. RESULTS: No statistically significant elevation in intraluminal pressure was detected immediately after placement of any filter. The clot-trapping ability of the spring filter and of Greenfield filter were slightly lower than that of the RF02 filter, but the differences were not statistically significant. After filters had trapped large clots, a high pressure gradient was detected in the 10.0-mm tube for all filters. The spring filter was associated with a higher pressure than the other filters in the 12.0-mm tube (P < .05). CONCLUSION: In vitro function of the spring filter was satisfactory in comparison with that of the RF02 filter and the Greenfield filter. For efficient filtering in the inferior vena cava, development of a larger version of the filter may be necessary.

Adjustable temporary venous spring filter: in vitro assessment.

RATIONALE AND OBJECTIVES: The authors performed an in vitro study to evaluate a temporary venous spring filter that can extend vessels of a wide range of diameters to a slit-shaped canal. MATERIALS AND METHODS: Filters were placed in thin polyethylene tubes or in porcine inferior vena cava specimens (diameter, 10.0-16.0 mm). Physiologic saline was substituted for blood flow, and blood clots of three sizes (6 x 10, 6 x 20, and 9 x 20 mm) were funneled to the filter. Clot-trapping ability was assessed by the degree of luminal extension. RESULTS: When the luminal extension was increased from 2.6r to 2.8r (where r is the original radius of the vein models), clot-trapping ability increased significantly (61.1%-87.5% in polyethylene tubes and 15.8%-77.5% in venous specimens, P < .001). When the luminal extension was increased to 3.0r, more than 90% of the clots were trapped in all tubes. After trapping the small, medium, and large clots, mean intraluminal pressure elevation was 1.0, 1.0, and 17.0 cm of saline, respectively. CONCLUSION: Despite its simple design, the spring filter proved to be an efficient filtering device.

Induced thrombosis in the pig inferior vena cava: a model of deep venous thrombosis.

PURPOSE: To establish a new animal model of deep venous thrombosis. MATERIALS AND METHODS: Fifteen young pigs underwent temporary interruption of the inferior vena cava (IVC) below the entry of the right renal vein by means of either a silicone band (surgical technique, n = 6) or an intraluminal balloon catheter (endovascular technique, n = 9), followed by injection of absolute ethanol. Lumbar veins within 3 cm below the obstruction were ligated or occluded interventionally. The iatrogenic caval obstruction was relieved after 2 days. RESULTS: Procedure-related mortality was 33% (n = 2) and 11% (n = 1) for the surgical and endovascular groups, respectively. An adherent, occlusive thrombus was found in all four of the remaining surgically treated animals and in six of eight animals treated percutaneously. The IVC remained patent in two animals in whom balloon migration occurred. Severe caval stenosis invariably occurred after surgical banding. CONCLUSION: IVC thrombi suitable for the study of various recanalization therapies can be reliably created with this pig model.

In vitro evaluation of a new temporary venous filter: the Spring filter.

PURPOSE: To evaluate in vitro the function efficacy of a new variable-sized, temporary venous filter, the Spring filter (SF). METHODS: The SF was tested in a flow phantom, using flexible, thin-walled polyethylene tubes 12, 14, and 16 mm in diameter to simulate veins. Clots of three sizes were used: 6 x 10 mm, 6 x 20 mm, 9 x 20 mm. Filter deployment was performed, ensuring that its functional diameter after placement was a predetermined multiple of the radius 'r' of the tube: 3.0r, 2.8r, 2.6r, 2.4r. The terminal coil was visually examined for changes in configuration. Clot retention by the filter for a period of 3 min was recorded as a success. The baseline intraluminal pressure and the maximum pressure reached after clot introduction were recorded. The trapping ability was calculated from the results for 10 clots. The effect of the following parameters on filter function were studied: size of embolus, caliber of simulated vein, and functional diameter of filter. RESULTS: The filter configuration was stable. Not a single instance of axial tilting occurred on deployment. Functional diameter was the major determinant of filter function. One hundred percent of clots were trapped irrespective of clot size and tube caliber when the functional diameter was 3.0r. Only 73% (95% confidence interval (CI): 57% - 88%) and 77% (95% CI: 61% - 92%) of small emboli were held up by the filter when the functional diameters were 2.6r and 2.4r, respectively (p = 0.0001). A significant reduction in clot trapping was encountered even with medium clots when the functional diameter was 2.4r (p = 0.02). CONCLUSION: Against the background of available data on retrievable vena caval filters, the current model of SF warrants further investigation.

[Selective catheterization of the inferior petrosal sinus]. / Selektiv kateterisering av sinus petrosus inferiores.

The inferior petrosal sinus is a dura sinus which traverses laterally and dorsally from the dorsal aspect of the cavernous sinus. It represents the nearest catheterization point for blood sampling from the pituitary gland. Inferior petrosal sinus venous sampling is used for diagnosis and lateralization of ACTH-secreting and growth hormone-producing hypophyseal adenomas. It is also used in the differential diagnosis of ectopic production of ACTH or other similar peptides. We briefly describe the anatomy of the inferior petrosal sinus and the catheterization technique, based on our experience from 15 patients. The endocrinological results are published in a separate article.

[Analysis of blood from the inferior sinus petrosus in patients with Cushing syndrome and acromegaly]. / Analyse av blod fra sinus petrosus inferior hos pasienter med Cushings syndrom og med akromegali.

Bilateral catheterization of sinus petrosus inferior was performed in ten patients with Cushing's syndrome and five patients with acromegaly. This was done in order to secure the diagnosis (Cushing's syndrome) and localize an adenoma (Cushing's syndrome and acromegaly). Blood from sinus petrosus inferior on both sides and from the peripheral vein was analyzed for concentration of ACTH or growth hormone after injection of ACTH-releasing hormone and growth hormone-releasing hormone respectively. The quotient between the ACTH concentration in blood from sinus petrosus and peripheral blood determines the diagnosis in Cushing's syndrome and the quotient between the concentration of ACTH or growth hormone between right and left sinus petrosus determines localization of the pituitary adenoma. Correct diagnosis and localization of ACTH-producing pituitary adenoma was found in eight of ten patients with Cushing's syndrome. One result was doubtful and one was wrong. In four patients with Cushing's disease (ACTH-producing adenoma) magnetic tomography (MT) was negative, but catheterization showed the presence of adenoma. In acromegalic patients, correct localization of the adenoma was determined in two out of five patients. In the other three patients, anatomical difficulties prevented satisfactory interpretation.

Safety of nonionic agents in visceral angiography.

RATIONALE AND OBJECTIVES: To compare the safety of ionic and nonionic contrast agents in visceral angiography. METHODS: Beginning in 1989, a prospective, open trial was begun, and 1,890 patients who have undergone contrast injection were enrolled. Patients considered to be high risk were graded according to Palmer and received nonionic contrast media, while all other patients received ionic contrast media. RESULTS: Because of the small number of visceral angiography procedures performed (38), no definitive conclusions could be drawn as to the differences between ionic and nonionic agents regarding grade-2 and grade-3 adverse events. However, a difference in grade-1 events was apparent in favor of nonionic agents. CONCLUSIONS: More than 10 years ago, the Department of Radiology staff at Aker Hospital began using iohexol, first in infants, then in children, pregnant women, patients undergoing leg phlebography, and patients with serious, previously documented reactions from contrast media. Currently, the department staff administers nonionic agents exclusively for coronary angiography and other cardiac procedures in approximately 300 patients per year. Today, use of nonionic contrast media is the standard for almost all procedures requiring intra-arterial or intravenous application.

[Embolization of bronchial arteries in severe and recurrent hemoptysis]. / Embolisering av bronkialarterier ved alvorlige og residiverende hemoptyser.

Bronchial artery embolization is an established treatment for massive and serious haemoptysis. We review etiology, pathogenesis and different treatment modalities of major haemoptysis, and discuss indications and outcome. Massive haemoptysis, defined as > 300 ml/24 hrs., is a rare condition with a high mortality rate (30-80%) if treated conservatively. We describe seven patients treated with bronchial artery embolization. Three patients had massive haemoptysis, and four patients were treated for recurrent and severe haemoptysis. Two patients had haemorrhage because of inactive tuberculosis, five had cystic fibrosis. All patients were successfully treated by embolization, one patient suffered recurrent haemoptysis after four weeks. The other patients have shown no further haemoptysis during the observation period (mean 20 months). No complications were observed other than the common, self-limited post-embolization syndrome (mild fever and chest pain). In patients with severely reduced lung function and progressive disease, recurrent haemoptysis of even smaller amounts might interfere with postural drainage and cause infections and deteriorate lung function. Bronchial artery embolization should be considered for these patients as well. Unless localized lesions can be cured through surgical resection, we consider bronchial artery embolization to be the treatment of choice.

[Chronic intestinal ischemia]. / Kronisk intestinal ischemi.

The syndrome of intestinal angina is rare and can be effectively treated by revascularization of the obstructed arteries. Usually the time from onset of symptoms to diagnosis is several months. Because of abdominal pain and loss of weight, abdominal malignancy is often suspected. At present there is no specific diagnostic test, and angiography with two projections is necessary. During the last decade 373 patients with intestinal angina have been reported. Our group presents two patients who have been operated on. After a follow-up of 18 and 19 months respectively, they are still without symptoms.

Water-soluble contrast media in radiography of small bowel obstruction. Comparison of ionic and non-ionic contrast media.

Fifty patients with possible gastrointestinal obstruction, referred for enteric follow-through examination, were randomized for a double-blind, parallel comparison of the hyperosmolar contrast medium Gastrografin and the low-osmolar Omnipaque. The result was that Omnipaque retained its radiographic density in the small bowel better than Gastrografin. Omnipaque was thus a better alternative than Gastrografin in follow-through examinations of intestinal obstruction. Also, 23 patients out of 28 with small bowel obstruction due to peritoneal adhesions, had spontaneous relief of symptoms during the observation period following contrast medium ingestion with no significant difference between the two media. This indicated that enteric follow-through procedures may have a therapeutic efficacy similar to the treatment of small bowel obstruction using nasogastric suction and gastrointestinal rest. Possible mechanisms for this action of the contrast media are discussed.

Iohexol in phlebography of the leg. A comparative investigation with meglumine metrizoate.

Comparing iohexol 240 mg I/ml, iohexol 300 mg I/ml and meglumine-Ca metrizoate 200 mg I/ml in phlebography of the leg in patients on or without anticoagulants, no sign of postphlebographic thrombosis was found using the 125I-fibrinogen uptake test and repeat phlebography. More adverse reactions occurred with metrizoate than with iohexol. Metrizoate provided significantly poorer demonstration than the two iohexol concentrations with higher iodine content.

Phlebography. Survey and present state.

Milestones in the history of phlebography are shortly reviewed. The present state of phlebography with emphasis upon the role of new nonionic contrast media is presented.

Management of retained biliary calculi via a postoperative T-tube tract.

Of 12 patients admitted for percutaneous retrieval of retained biliary stones through a postsurgery T-tube tract, 10 patients were successfully treated. The method using catheter technique and Dormier basket is reviewed.