Iontophoretic Catheter Research Articles

Silver Cannula in Main Right Bronchus

A silver iontophoretic catheter was designed consisting of two silver wires connected to an electric power source and disposed in a parallel and helical manner around the proximal subcutaneous segment of a silicone catheter. In an in vitro tunnelled bridge model the silver iontophoretic catheter prevented the migration of Staphylococcus epidermidis from the highly contaminated hub to the sterile tip over a 40-d period. The silver impregnated cuff and electrically charged wires made of aluminium or iron delayed migration for only 72 h. A modified Kirby-Bauer technique, used to test the inhibitory activity of antimicrobial catheters, showed that the silver iontophoretic catheter has a broad spectrum inhibitory activity against Gram-positive bacteria, Gram-negative bacteria and Candida albicans. The silver iontophoretic catheter provides a long-term electrochemical barrier against the migration of organisms from the external contaminated environment into the sterile intravascular compartment.

Evaluation of the silver iontophoretic catheter in an animal model

Silver iontophoretic catheters (SIC) were shown to be highly efficacious in preventing catheter infections in vitro and in a rabbit model (J. Infect. Dis. 173 (1996) 495). Furthermore, we sought to determine the safety and durability of SIC prior to use in humans. A total of 30 New Zealand white rabbits (3–4 kg) were randomly assigned to one of three groups whereby SIC or Arrow Guard (AG) catheters were tunneled and inserted in the jugular vein. All animals were followed for 2–12 weeks after catheter implantation. Blood was collected from each rabbit for assessment of toxicity and determination of silver levels. The electrical current generated by each SIC was measured once daily. At the end of the follow-up period, tissue samples were collected from the skin surrounding the catheter, the lungs, spleen, and liver. Microscopically, none of the tissues examined from any of the animals showed evidence of silver deposits, silver toxicity, thermal or electrical injury. The silver levels in the animals that received the SIC ranged from 0.1 to 2.23 μg/l with a mean of 0.62 (±0.44 SD). In conclusion SIC were safe with normal serum silver levels and were not associated with any local or systemic toxicity.

Iontophoresis as a new method of delivering local anesthesia to the urethra: a pilot study

Objectives. To test the feasibility of using the iontophoretic catheter as a means of delivering local anesthetic (lidocaine hydrochloride) to the urethra for periurethral injection of collagen. Methods. Eight women with urodynamically proven genuine stress incontinence underwent periurethral collagen injections. Local anesthesia was provided by 4% lidocaine with 1 in 100,000 epinephrine administered over 10 minutes using an iontophoretic catheter. Pain was assessed by Likert and visual analogue scales. Cystoscopic appearance of the urethra was noted. Results. The periurethral bulking procedure was completed without further anesthetic in 7 women, 1 of whom had no pain. There was no evidence of urethral damage from the iontophoresis. Conclusions. Iontophoresis shows promise as a method of providing analgesia to the urethra. However, the degree of analgesia is variable, and further research is needed on catheter design to ensure transport of anesthetic agent into the periurethral tissues.

Local Delivery of 125I-labeled ReoPro to Baboon Brachial Arteries Using an Iontophoretic Balloon Catheter

Local Delivery of 125I-labeled ReoPro to Baboon Brachial Arteries Using an Iontophoretic Balloon Catheter

Pharmacokinetics and tissue localization of antisense oligonucleotides in balloon-injured pig coronary arteries after local delivery with an iontophoretic balloon catheter.

When delivered locally to the arterial wall by passive fluid transfer systems such as perforated balloons, water-soluble compounds in aqueous solution are not readily taken up by tissue, show low levels of cellular localization, and are quickly lost by wash-out. One approach to improve delivery is addition of an "active" component to the catheter system to change the nature of the drug-to-tissue interaction. Using an iontophoretic balloon catheter to deliver antisense oligonucleotide (ODN) to pig coronary arteries after balloon angioplasty, we determined the quantity and localization of ODN in the tissue. By radiolabeling, 7.3 +/- 2.4 micrograms ODN was present at 30 min, 1.5 +/- 0.6 at 2 h, 0.52 +/- 0.35 at 24 h, and 0.26 +/- 0.11 at 7 d. By fluorescent labeling, circumferential medial uptake and adventitial delivery at the site of medial injury was observed, with primarily cellular localization. The iontophoretic catheter thus appears to be a useful device for ODN delivery to arterial tissue.

Localized delivery of heparin to angioplasty sites with iontophoresis.

Drug delivery by iontophoresis involves the application of an electric field to move selectively charged drug molecules across biological membranes. The purpose of this study was to assess the efficacy of intravascular iontophoresis in the local delivery of heparin to balloon angioplasty sites by using a recently designed iontophoretic catheter. In vivo heparin iontophoresis was assessed in 33 rats and 21 pigs in four protocols designed to measure the technical determinants of intramural drug deposition, the pharmacokinetics and localization of coronary delivery, and the effect of this technique on platelet deposition following balloon injury. First, iontophoresis of 3H-heparin into the aorta of 33 rats was performed to determine the effects of iontophoretic current, iontophoretic membrane balloon initiation pressure, iontophoresis time, and heparin concentration on intramural drug deposition. Second, iontophoresis of 3H-heparin was performed in 16 porcine coronary arteries to quantitate immediate drug delivery and subsequent wash-out over 24 h. Third, iontophoresis of fluorescent heparin was performed in 8 porcine coronary arteries to define intramural localization of locally delivered drug. Fourth, 111In-labeled platelet deposition was measured 1 h following balloon angioplasty and local iontophoretic heparin delivery in 16 porcine carotid and iliac vessels. Contralateral control vessels that were dilated with the same size balloon and treated with iontophoresis of saline served as controls. Rat aortic studies demonstrated that iontophoresis resulted in 13 times more intramural heparin deposition than passive delivery (passive: 0.3 +/- 0.4 microgram, iontophoresis: 4.6 +/- 1.6 micrograms, P < 0.0004). Iontophoretic membrane balloon inflation pressure had no significant effect on intramural drug deposition, but longer iontophoresis times and higher heparin concentrations resulted in higher levels of intramural heparin (P < 0.05). Porcine coronary studies demonstrated successful intramural deposition of heparin in all arteries without adverse electrical or hemodynamic sequelae, with persistence of the drug for at least 24 h. Localization studies demonstrated immediate deposition of fluorescent heparin in the intima and internal elastic lamina, with subsequent rapid diffusion of the drug into the media. Porcine platelet studies demonstrated that heparin iontophoresis decreased platelet deposition following balloon injury by approximately 66% compared with saline-treated control vessels (heparin-treated: 1.46 +/- 2.51 x 10(8), control: 4.27 +/- 7.02 x 10(8), P = 0.001). This study has demonstrated that local intramural heparin delivery is feasible with an intravascular iontophoretic catheter. Following intracoronary heparin iontophoresis in the porcine model, intramural drug is detected for at least 24 h. Local delivery of heparin with this technique significantly decreases early platelet deposition following balloon injury in peripheral porcine arteries.

Pharmacokinetics and tissue localization of antisense oligonucleotides in balloon‐injured pig coronary arteries after local delivery with an iontophoretic balloon catheter

Pharmacokinetics and tissue localization of antisense oligonucleotides in balloon‐injured pig coronary arteries after local delivery with an iontophoretic balloon catheter

In vitro antimicrobial efficacy of silver iontophoretic catheter

A silver iontophoretic catheter was designed consisting of two silver wires connected to an electric power source and disposed in a parallel and helical manner around the proximal subcutaneous segment of a silicone catheter. In an in vitro tunnelled bridge model the silver iontophoretic catheter prevented the migration of Staphylococcus epidermidis from the highly contaminated hub to the sterile tip over a 40-d period. The silver impregnated cuff and electrically charged wires made of aluminium or iron delayed migration for only 72 h. A modified Kirby-Bauer technique, used to test the inhibitory activity of antimicrobial catheters, showed that the silver iontophoretic catheter has a broad spectrum inhibitory activity against Gram-positive bacteria, Gram-negative bacteria and Candida albicans. The silver iontophoretic catheter provides a long-term electrochemical barrier against the migration of organisms from the external contaminated environment into the sterile intravascular compartment.

Silver Iontophoretic Catheter: A Prototype of a Long-Term Antiinfective Vascular Access Device

A silver iontophoretic catheter (SIC) was developed consisting of two electrically charged parallel silver wires helically wrapped around the proximal segment of a vascular catheter. In vitro and in vivo activities of this catheter were compared with those of an aseptic catheter coated with chlorhexidine and silver sulfadiazine (CH/SS). The SIC demonstrated broad-spectrum in vitro inhibitory activity against bacteria and Candida albicans comparable to that of the CH/SS-coated catheter. The durability of activity was determined by incubating catheters in serum at 37 degrees C for various time intervals. After 30 days, the antimicrobial activity of the SIC did not change significantly, while that of the CH/SS-coated catheter was reduced to a suboptimal level. In a rabbit model, the SIC was safe and significantly more efficacious than the CH/SS-coated catheter in preventing colonization with Staphylococcus aureus (P < .05). The SIC has broad-spectrum inhibitory activity of long durability and is highly efficacious in preventing colonization in vivo.

In Vivo Reduction of Bacterial Populations in the Urinary Tract of Catheterized Sheep by Iontophoresis

Purpose Iontophoresis kills microbes in vitro and, therefore, may be a useful method for eliminating microbial populations associated with catheter-induced urinary tract infections in vivo. Materials and Methods Catheters were modified to deliver current to platinum electrodes in the catheter tip. Female sheep were catheterized with this iontophoretic catheter and left ambulatory. In 5 sheep (experimental group) 400 microampere was applied to the catheter and withheld in 4 sheep (control group) for 20 to 21 days. The animals were then sacrificed. During the study, types and concentrations of bacteria, and physical and chemical characteristics of the urine samples were determined. Results Throughout the study, bacteria levels were reduced in urinary tracts of the experimental group (10 3 to 10 4 microbes per ml.) compared with the control group (10 7 microbes per ml.), without extensive alterations to urine chemistry or the sheep urinary tract. Conclusions Since iontophoresis safely reduced bacterial populations in catheterized sheep, this technology may reduce or eliminate nosocomial, catheter-induced urinary tract infections in humans.

996-11 Direct Gene Transfer and Expression with Arterial Iontophoretic Catheter Delivery

Iontophoresis is a technique of molecular delivery which uses electric current to enhance movement of charged molecules into tissues. A porous balloon catheter was tested with a central silver chloride electrode capable of generating a potential gradient across the arterial wall using an adhesive patch placed on the skin to serve as the anode. We hypothesized that this catheter delivery system might effectively transfer negatively charged plasmid DNA into arterial cells in vivo. To localize plasmid DNA arterial delivery, a 7 Fr iontophoretic porous balloon catheterwast,’aced into porcine carotid arteries underflouroscopic guidance. 15 μg of 35S-Iabeled plasmid DNA (1.4 × 106 cpm/μg) expressing the heat stable human alkaline phosphatase (hAP) gene with an RSV promoter was infused through the balloon at 6 atm pressure. A constant current density of 2.5 mA/cm2 was maintained for 10 minutes. The ;35S-labeled plasmid DNA delivery was repeated on the contralateral carotid artery under identical conditions with the absence of electric current. 20 minutes after gene transfer, the arteries were fixed in situ and processed for autoradiography. To analyze gene transfer and expression, 8 porcine carotid arterial segments were subject to iontophoretic gene delivery for 10 minutes at 6 atm with a current density of 2.5 mA/cm2 using the RSV hAP plasmid (n = 6) or control plasmid (n = 2). Animals were sacrificed 5 days after gene delivery and the transfected arteries analyzed by PCR and heat stable alkaline phosphatase histochemistry. Autoradiography of the arteries which underwent ;35S-labeled plasmid delivery revealed minimal radiolabel in the luminal cells of the control artery in which current was not delivered. In contrast, significant amounts of radiolabel were present in the media and adventitia of the artery subject to current delivery. PCR analysis of the arterial segments studied 5 days after delivery confirmed gene transfer in all hAP segments and was negative in control arteries. Staining for heat stable recombinant alkaline phosphatase activity demonstrated recombinant protein expression in 5% of medial cells and 10% of adventitial cells in arteries which underwent hAP gene transfer. Control arteries were negative for hAP staining. Iontophoretic catheter gone delivery can be used to perform direct plasmid DNA delivery with expression of recombinant protein in medial and adventitial cells.

Electrode and Bacterial Survival with Iontophoresis in Synthetic Urine

Urinary catheters, especially in patients with long-term catheter requirements, frequently are a source of infection. Iontophoresis has been proposed as a method to decrease or eliminate such infections. Several types of material were examined for their potential use as electrodes in an iontophoretic catheter system. Silver, copper and nickel electrodes did kill microorganisms but did not show longevity. Carbon and gold electrodes showed longevity and killing of microorganisms. Gold proved to be somewhat better than carbon in killing Klebsiella pneumoniae in a broth. Few organisms survived iontophoresis. Those few that survived (mainly Klebsiella in broth), when rechallenged by iontophoresis, did not show any striking resistance to iontophoresis. Our data support the proposition that inclusion of electrodes, depending on the electrode type, in a catheter probably will decrease or eliminate a bacterial population in urine and, thus, may help prevent catheter-related infections and their sequelae.