Outer Catheter Research Articles

A New Hemostatic Procedure for Percutaneous Transhepatic Portal Vein Catheterization

To avoid major complications, such as intraperitoneal bleeding after percutaneous transhepatic catheterization, a new technique has been developed. In this procedure, a stick-like gelfoam sponge compressed manually and loaded in a cartridge, is inserted through an outer sheath catheter after the removal of the catheter, and the puncture hole is plugged. No bleeding has been experienced in 56 patients with various hepatic diseases since using this method.

Technique and preliminary results of interstitial irradiation for primary brain tumors.

We have conducted a phase-I clinical trial of CT-guided stereotactic implantation of Ir192 in the treatment of malignant astrocytomas. During the past year, 16 patients have been implanted with two to four catheters in the residual enhancing portion of their tumor. These patients represent 50% of our total experience with the CT compatible Leksell frame. Each catheter contains three to six high intensity (2.0 to 2.5 mg Ra equivalent) seeds with 0.5 cm separation between the sources. The total activity of Ir192 per implant has been 30-65 mg radium equivalent. In the 16 patients, 49 catheters have been placed, an average of three targets calculated per patient and no targets have been missed. The radiation exposure to personnel has been surveyed in detail and drops off to less than 2 mr/h six feet from the patient when our custom-built radiation shield is employed. We have reserved permanent implantation of I125 for patients with tumors in unusual locations (e.g. pineal) or for individuals with slowly growing non-gliomatous lesions (i.e. meningioma). The tumor volumes have ranged from 12-120 cm3. Unique aspects of our implant procedure include the use of a Leksell frame already adapted to the GE-8800 scanner, the use of pre- and post-implant computerized treatment planning programs to determine the dose distribution profiles and the use of adjustable metal collars crimped to the outer catheters to provide ease of insertion, uniform pre-implant catheter length, and protection against source migration. Two of our patients have suffered from subacute radiation reactions, primarily due to delayed cerebral edema and both of these cases have largely resolved.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental evaluation of a new instrument for transcatheter electrocoagulation.

A new coaxial electrode catheter design has been tested in 19 renal arteries of pigs with excellent results, i.e. 100 per cent thrombosis. One vessel ruptured. The electrode (anode) is situated on a thin inner catheter and after electrolysis it is pulled back into a shielding outer catheter. This should reduce downstream embolization. Usual currents have been 8 to 10 mA at 10 V and doses of 16 to 36 C have been used depending on the size of the artery. In the single case of rupture of the vessel a current of 20 mA was used. The method appears to be ready for clinical testing.

Surface modification and evaluation of some commonly used catheter materials. I. Surface properties.

Double catheter systems consisting of a stiff outer catheter and a flexible, buoyant, flow-directed, inner catheter which is often balloon-tipped have been employed with increasing frequency recently in both therapeutic and diagnostic procedures. Their use, however, has been restricted because of the excessive friction generated between the two catheters. In an attempt to decrease friction between polymers commonly used as catheter materials, oxidation of polyethylene, fluorinated ethylene-propylene copolymer, poly(vinyl chloride), silicone rubber, and polystyrene surfaces was induced by exposing the polymers to radio frequency glow discharge (RFGD) in a helium environment. All polymers were surface characterized utilizing x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and contact angle measurements before and after oxidation. This article describes the materials and methods used to fabricate and characterize the polymer surfaces and the results of the characterization. The results indicate that increases in oxygen concentration at the surface of the polymers and decreases in air-water contact angles occur with increased RFGD exposure time. Plateau values were usually obtained after 5-30 s exposure time, yet no apparent changes in surface topography were noted by scanning electron microscopy. The hydrophilic surfaces produced were stable for up to three months storage time in air.

Intracoronary thrombolysis in evolving myocardial infarction

After experimental studies in dogs confirmed the feasibility and safety of rapid intracoronary thrombolysis by local infusion of Thrombolysin (streptokinase and plasmin), intracoronary thrombolysis was attempted in 20 patients with evolving myocardial infarction who were hospitalized within 3 hours from the onset of symptoms during the day and within 2 hours at night. Thrombolysin was infused in the immediate vicinity of the site of coronary occlusion using a 0.85 mm outer diameter catheter advanced through the lumen of the Judkins catheter. Reperfusion was achieved in four patients after an average of 43 minutes of Thrombolysin infusion at a rate of 2000 IU/min and in 15 patients after an average of 21 minutes of Thrombolysin infusion at a rate of 4000 IU/min. The failure to open the artery in one patient may have been caused by our inability to advance the infusion catheter close to the site of occlusion. Rethrombosis occurred in one patient 8 days after reperfusion and 2 days after discontinuation of anticoagulants because of a history of chronic alcoholism. Wall motion and perfusion studies showed improvement following reperfjsion. Patency of the artery was achieved an average of 4 hours after the onset of symptoms. The need for earlier reperfusion is emphasized.

Modified Catheter for Percutaneous Transluminal Treatment of Arteriosclerotic Obstructions

Experience with transluminal dilatation of superficial femoral artery stenoses resulted in modification of the original outer catheter because of the following problem. The patient in Figure 1, A and B had generalized arteriosclerosis and one severely stenotic segment in the superficial femoral artery at the adductor hiatus. Although containing some atheromatous plaques, the popliteal artery was patent. Transluminal dilatation was carried out by the method of Dotter and Judkins (1–3). No difficulty was encountered in dilating the stenotic segment with the wire guide or with the small catheter. After the stenosis was traversed by the larger catheter, arteriography showed that the previously stenotic segment was now wide open. A stenosis had developed in the originally patent popliteal artery (Fig. 1, C), however, and atheromatous material had apparently been deposited in the lumen of the popliteal artery. I postulated that the difficulty arose from a “snow-plow” effect due to a small ridge which formed around the second catheter when it was passed over the first. A roentgenogram (Fig. 2, A) of the original catheters shows this sharp ridge formed by the junction of the leading edge of the outer catheter and the outside surface of the inner catheter. In a tight stenosis first traversed by the tapered inner catheter, the ridge of the outer catheter can push atheromatous material ahead of it rather than compress it to the sides of the lumen as was originally intended (Fig. 3, A). This thesis is supported by the appearance of the vessel wall at the original superficial femoral artery stenosis following dilatation. The step-like configuration suggests a gouging out of an atheromatous plaque (Fig. 1, C, arrow). The manufacturer2 modified the larger catheter so that the tip was molded to the diameter of the wire guide. Figure 2, B demonstrates the relationship of the modified outer catheter to the inner catheter and guide. The outer catheter has a smooth transition from the wire guide to its greatest diameter. The smooth change in diameter allows the tip of the catheter to occupy the space previously dilated by the smaller catheter. The proximal gradually widening larger tube then compresses the atheromatous material against the vessel wall (Fig. 3, B). With this arrangement the larger catheter cannot be passed over the smaller tubing. Therefore, after dilatation has been accomplished with the smaller catheter, it is removed and the larger catheter is inserted over the wire guide. This is no different from exchanging catheters in any vascular diagnostic catheter procedure. If more stiffness is required, the smaller catheter can be reintroduced inside the larger catheter. If this is not sufficient, a long metal cannula provided by the manufacturer can be passed over the wire guide inside the smaller catheter to increase stiffness in penetrating the stenosis.

Central venous pressure monitoring: A useful guide to fluid therapy during shock and other forms of cardiovascular stress

Important relationships between venous pressure, blood volume, and cardiac output were described over fifty years ago, but the clinical application of peripheral venous pressure measurements was limited by errors in methodology and by incomplete physiologic data on the function of the venous system. There has been a recent renewal of interest in the venous system due to the advent of open heart surgery and additional physiologic data indicating that central venous pressure could be measured more accurately and would have more clinical usefulness than peripheral venous pressures. The description of new technics for cannulation of the central venous system by Richards and associates, [19] Hughes and Magovern, [20] Aubainac, [22] Keeri-Szanto, [24] and Wilson, Grow, and Demong [25] made monitoring of CVP a simple bedside procedure. A further modification of Wilson's technic involves the use of a 15 gauge, 6 inch, Rochester needle, which is introduced percutaneously into either subclavian vein. The needle is removed, leaving the outer catheter in place. A Seldinger guide wire is used to thread the catheter into the superior vena cava without fluroscopic guidance. A total of 132 catheterizations of the superior vena cava have been carried out by this technic, with a 8.3 per cent complication rate, none of which were serious. None resulted in death of the patient. CVP is not a linear function of blood volume, except under special controlled conditions that rarely exist in clinical practice. Therefore, CVP cannot be used to estimate blood volume. CVP, on the other hand, is an expression of the rate of venous return compared with the myocardial competency (the ability of the heart to handle the venous return). Since the terms “rate of venous return” and “effective circulating blood volume” are functionally similar, CVP can be used as a measure of the effective circulating blood volume related to the competence of the heart. Isolated absolute CVP measurements are of little value unless they are unusally high or low. Continuous monitoring of CVP and correlation of changes in pressure with volume expansion or contraction are useful guides to fluid therapy. CVP monitoring is an adjunctive procedure that facilitates the diagnosis and treatment of abnormal circulatory states and is most useful when related to other data, such as history, physical findings, urinary output, systemic blood pressure, pulse pressure, blood volumes, and cardiac output.