231 ESTABLISHING AN INTERVENTIONS BUNDLE TO IMPROVE INPATIENT CARE FOR PATIENTS WITH PARKINSON’S DISEASE: A MULTIDISCIPLINARY QUALITY IMPROVEMENT PROJECT

Background

Patients with Parkinson’s (PwP) are at a higher risk of complications once admited to hospital compared to their age-matched peers. Medication mismanagement is a well-known obstacle, which puts PwP at risk of sub-optimal treatment leading to an unnecessary deterioration of baseline and potentially increases risk of adverse sequelae.

Methods

Retrospective electronic patient records (EPR)/chart review of 47 admissions was conducted, across three hospital sites.

Data attaining to correct prescribing of medication on admission and discharge, prescribing of contraindicated medications, reasons for medication lapses and complications of inpatient stay were collected. EPR of 17 patients’ were reviewed to assess if Parkinson’s disease (PD) medication administrations occurred within 30 minutes of patient schedule, as recommended by NICE guidelines. Key areas for improvement were identified based on the results.

Results

47 charts (30 Males, 17 Females) with mean age 72 (range:57–90), were reviewed. Average number of co-morbidities:4.5 and Clinical Frailty Scale ranged 5–9 (n = 30). LOS averaged 12.4 days and 43% of patients had ≥2 hospital admissions in the preceeding year.

38% (17/44) of admissions correctly documented patient specific medication times. Only 48% of patients (n = 638) received their medications within 30 minutes of the scheduled time. 47% (22/47) experienced complications attributable to PD. Contraindicated medications were noted in 5 cases. 84% of discharging prescriptions did not mention timing of PD medication and 3 prescriptions had errors with regards to dosage/omission of medication.

Conclusion

We implemented across two sites: 1) Care protocol flag in patient’s chart highlighting simple avoidable complications. 2) Laminated over the bed signpost alerting ‘time critical medication’. 3) ‘Time critical medication’ stickers in drug kardex 4) Education sessions for Medical, Nursing and Ward staff. 6) Establishing out of hours access to PD medications and protocols for NPO/poor swallow. We plan to reassess significance of efforts post intervention.

The Role the Frailty Syndrome Can Play in Advocacy and Resource Allocation for Our Ageing Population - Findings in a Dublin Day Hospital

Frail individuals are at higher risk of adverse outcomes, and need identification and priority access to Comprehensive Geriatric Assessment (CGA). We prospectively collected data on new referrals to our day hospital. Levels of frailty were measured with the SHARE Frailty Instrument for Primary Care (SHARE-FI). Of 257 patients assessed (90 men, 167 women), 110 (43%) were non-frail, 66 (26%) pre-frail and 81 (32%) frail. Mean age was 82 years for the non-frail, 83 for the pre-frail and 84 for the frail. Forty-one percent of the frail reported two or more falls in the preceding year, compared to 38% of the pre-frail and 21% of the non-frail (P for trend = 0.003). Of 27 patients who were referred for ongoing multidisciplinary assessment and rehabilitation, 16 (59%) were frail. The frailty syndrome has the potential to become an advocacy tool for older people and help target effective, but finite, CGA resources.

Rheumatic heart disease in pregnancy: cardiac and obstetric outcomes

BACKGROUND

Rheumatic heart disease (RHD) remains an important health issue for indigenous women of child-bearing age in northern Australia. However, the influence of RHD on maternal outcomes with current clinical practice is unclear.

AIMS

To determine maternal cardiac complications and obstetric outcomes in patients with RHD.

METHODS

Retrospective case note analysis of women with RHD who received obstetric care between July 1999 and May 2010 at Cairns Base Hospital in north Queensland. Outcome measures were obstetric interventions and outcomes, cardiac interventions and complications, stratified according to a cardiac risk score (CRS).

RESULTS

Ninety-five confinements occurred in 54 patients, of whom 52 were Indigenous Australians. There were no maternal or neonatal deaths. With a CRS of 0, cardiac complications occurred in 0 of 70 confinements; with a CRS of 1, complications occurred in 5 of 17 confinements (29%); with a CRS of >1, complications occurred in 2 of 4 confinements (50%). Another four patients were first diagnosed with RHD after developing acute pulmonary oedema during the peripartum period.

CONCLUSIONS

  RHD has a major impact on maternal cardiac outcomes. However, with current management practices, maternal and fetal mortality are low, and the incidence of complications is predictable based on known risk factors.

In vitro and in vivo evaluation of the safety and stability of the TAXUS Paclitaxel-Eluting Coronary Stent

Functional aspects of the styrene-b-isobutylene-b-styrene triblock copolymer (SIBS) which is incorporated into a drug-eluting stent (DES) coating are described. The SIBS copolymer is employed on the TAXUS Paclitaxel-Eluting Coronary Stent as a carrier for paclitaxel (PTx). Optical and scanning electron microscopic analysis of stents explanted from rabbit and porcine models after 2 years and 6 months, respectively, showed that the SIBS coating maintained physical integrity. Gel permeation chromatography (GPC) of the copolymer extracted from the coating verified that no polymer degradation occurred over the same period of time. The coating on TAXUS Stents was shown to maintain physical integrity after 400 million cycles of pulsatile or mechanical (tensile) fatigue, simulating 10 years real time use. Inspection of the samples compared to untested controls showed no change in the coating under these cyclic simulated conditions. Films prepared with the same formulation found on TAXUS Stents maintained mechanical strength and resistance throughout the time of testing. Intentional defects introduced into the stent coating were shown to have only a minimal impact on PTx release. These data support the suitability of the SIBS copolymer as a drug carrier for DES applications.

Intravenous oxytocin bolus of 2 units is superior to 5 units during elective Caesarean section

BACKGROUND

The optimal dose of oxytocin at Caesarean section is unclear. Oxytocin may cause adverse cardiovascular effects, including tachycardia and hypotension, whereas an inadequate dose can result in increased uterine bleeding. We compared the effects of two doses of oxytocin in a randomized double-blind trial.

METHODS

Eighty patients undergoing elective Caesarean section received an i.v. bolus of either 2 or 5 units (u) of oxytocin after delivery, followed by an oxytocin infusion of 10 u h(-1). All received combined spinal-epidural anaesthesia with arterial pressure maintained by a phenylephrine infusion. We compared changes in heart rate (HR), mean arterial pressure (MAP), blood loss, uterine tone, the need for additional uterotonic drugs, and emetic symptoms.

RESULTS

There was a greater increase in mean (sd) HR in patients who received 5 u of oxytocin [32 (17) beats min(-1)] than in those who received 2 u [24 (13) beats min(-1)] (P=0.015). There was a larger decrease in MAP in patients who received 5 u [13 (15) mm Hg] than in those who received 2 u [6 (10) mm Hg] (P=0.030). The frequency of nausea and antiemetic use was higher after 5 u (32.5%) than 2 u (5%) (P=0.003). There were no differences in blood loss, uterine tone, or requests for additional uterotonic drugs (17.5% in both groups).

CONCLUSIONS

In elective Caesarean section, a 2 u bolus of oxytocin results in less haemodynamic change than 5 u, with less nausea and no difference in the need for additional uterotonics.

Group therapy for patients with psychogenic nonepileptic seizures: a pilot study

Great advances have been made in the diagnosis of people with psychogenic nonepileptic seizures (PNES) since the advent of video/EEG monitoring. However, treatment options for this population have lagged significantly. This pilot study was undertaken to evaluate whether group therapy done with a psychodynamic focus would offer a useful intervention. Twelve patients entered the study and seven completed at least 75% of the 32 weekly sessions. The Beck Depression Inventory and the Global Severity Index of the Symptom Checklist-90 showed improvement as well as an overall decrease in PNES frequency. The data suggest that group therapy focusing on interpersonal issues may benefit patients with PNES.

Cytostatic activity of paclitaxel in coronary artery smooth muscle cells is mediated through transient mitotic arrest followed by permanent post-mitotic arrest: comparison with cancer cells

The anti-cancer agent paclitaxel (PTX) is an effective anti-restenosis agent on drug eluting stents, primarily due to growth inhibition of coronary artery smooth muscle cells (CASMC) across a wide dose range. In this study, we compared the effects of PTX on CASMC to apoptotic-prone HL60 leukemia cells and apoptotic-reluctant A549 lung cancer cells to assess cell survival mechanisms. In comparison to HL60 and A549 cells, CASMC had a shorter mitotic arrest and a lower mitotic index. While CASMC and A549 cells did not become apoptotic and displayed a multi-nucleated phenotype, HL60 cells showed prolonged mitotic arrest followed by apoptosis. CASMC exiting mitosis were arrested in G1 as MN tetraploid cells, with decreased levels of cyclin B1 and PCNA. CASMC remained metabolically active, becoming permanently arrested as evidenced by increased levels of beta-galactosidase activity. These cells did not demonstrate elevated levels of inflammatory markers. Our findings suggest that a weak mitotic checkpoint or inhibited apoptotic cascade, or a combination of both, determine cell survival following PTX treatment. These in vitro findings suggest a mechanism for the cytostatic activity of PTX in CASMC for the inhibition of restenosis.

The Taxus drug-eluting stent: a new paradigm in controlled drug delivery

The advent of drug-eluting stents (DES) has provided the medical community with a technology that is transforming the treatment of coronary artery disease. As the newest treatment modality available to the interventional cardiologist, drug-eluting stents have not only significantly reduced the risk of restenosis, but they are also allowing the interventionalists to treat more complex lesions in patients that would otherwise require more invasive bypass surgery. Development of these drug-device combination products has presented considerable challenges to the device industry because it involves a multi-disciplinary approach that combines conventional device design and manufacturing with the principles of controlled local drug delivery. This review article provides an in-depth discussion of the key elements of drug-eluting stents, focusing on the TAXUS paclitaxel-eluting stent as an example of this new class of product. Specific sections will review the drug and polymer matrix components, formulation development and evaluation, pre-clinical studies and clinical trial results.

Local administration of NF-kappa B decoy oligonucleotides to prevent restenosis after balloon angioplasty: an experimental study in New Zealand white rabbits

PURPOSE

To evaluate the efficacy of NF-kappa B oligonucleotides (ODN) administered by local administration with the channeled balloon catheter to prevent restenosis after balloon angioplasty in restenotic iliac arteries of New Zealand white rabbits.

MATERIALS AND METHODS

In vitro, 8000 rabbit vascular smooth muscle cells (rVSMC) where transfected with a liposomal carrier (TfX50) with 100 ng of decoy and scrambled ODN. Inhibition of proliferation was measured using a MTT assay after 24 hours in comparison to control. In vivo, 22 male New Zealand White rabbits were fed a 1% cholesterol diet and received denudation of both common iliac arteries with a 3 mm balloon catheter to induce an arterial stenosis. Four weeks after stenosis induction, local application of NF-kappa B in two different concentrations (1 mug: n = 14; 10 mug: n = 8) was performed randomly on one common iliac artery. Scrambled oligonucleotides without specific binding capacities were injected into the contralateral side. The channeled balloon catheter allows simultaneous balloon dilation (8 atm) of the stenosis and local application of a drug solution (2 atm). Four weeks after local drug delivery the animals were killed and the vessels were excised and computerized morphometric measurements were performed.

RESULTS

NF-kappa B decoy ODN but not scrambled ODN inhibited proliferation of rVSMC in vitro. Following local ODN application in the animals, no acute vascular complications were seen. NF-kappa B ODN resulted in a statistically non significant reduction of neointimal area compared to the control group. The neointimal area was 0.97 mm(2) using 1 mug NF-kappa B ODN compared to 0.98 mm(2) in the control group. The higher dose resulted in a neointimal area of 0.97 mm(2) compared to 1.07 mm(2) at the control side.

CONCLUSIONS

Local drug delivery of NF-kappa B ODN using the "channeled balloon" catheter could not reduce neointimal hyperplasia in stenostic rabbit iliac arteries. Application modalities have to be improved to enhance the effect of the local application to prevent restenosis after balloon angioplasty.

Paclitaxel induces primary and postmitotic G1 arrest in human arterial smooth muscle cells

Paclitaxel (PTX), a microtubule-active drug, causes mitotic arrest leading to apoptosis in certain tumor cell lines. Here we investigated the effects of PTX on human arterial smooth muscle cell (SMC) cells. In SMC, PTX caused both (a) primary arrest in G(1) and (b) post-mitotic arrest in G(1). Post-mitotic cells were multinucleated (MN) with either 2C (near-diploid) or 4C (tetraploid) DNA content. At PTX concentrations above 12 ng/ml, MN cells had 4C DNA content consistent with the lack of cytokinesis during abortive mitosis. Treatment with 6-12 ng/ml PTX yielded MN cells with 2C DNA content. Finally, 1-6 ng/ml of PTX, the lowest concentrations that affected cell proliferation, caused G(1) arrest without multinucleation. It is important that PTX did not cause apoptosis in SMC. The absence of apoptosis could be explained by mitotic exit and G(1) arrest as well as by low constitutive levels of caspase expression and by p53 and p21 induction. Thus, following transient mitotic arrest, SMC exit mitosis to form MN cells. These post-mitotic cells were subsequently arrested in G(1) but maintained normal elongated morphology and were viable for at least 21 days. We conclude that in SMC PTX causes post-mitotic cell cycle arrest rather than cell death.

Effect of ionizing radiation on the stability and performance of the TAXUS Express2 paclitaxel-eluting stent

BACKGROUND

The advent of drug-eluting stents has provided the interventional cardiologist an effective new tool in treating coronary restenosis. There remains, however, a small group of patients that still require intervention following drug-eluting stent therapy. Currently, intravascular brachytherapy (IVBT) is approved for use in the treatment of in-stent restenosis (ISR). This study investigated the effect of gamma and beta radiation doses typically used in IVBT on the performance of the TAXUS Express(2) paclitaxel-eluting stent.

METHODS AND RESULTS

It was determined that there were no statistically significant changes to in vitro paclitaxel release from stent exposed to radiation compared to controls subjected to the same conditions except for the radiation exposure. The molecular weight of the Translute polymer carrier matrix and the level of paclitaxel degradants were not changed following exposure to radiation doses up to twice what is typically used in IVBT. Beta and gamma radiation doses typically used in IVBT had no significant effect on the Translute polymer carrier, paclitaxel degradation, or paclitaxel release in this in vitro model.

CONCLUSION

The data are encouraging and support further evaluation of the use of IVBT in the treatment of ISR in the presence of drug-eluting stents.

Effects of altering infusion parameters on intimal hyperplasia following local catheter-based delivery into the rabbit iliac artery

BACKGROUND

Efficient local gene or drug therapy requires optimized application modalities to avoid vessel damage, which might lead to increased neointimal hyperplasia. Aim of the study was to evaluate different application parameters for local delivery using the channeled balloon catheter in order to minimize vessel trauma induced by local application.

METHODS AND RESULTS

Sixty cholesterol fed rabbits were randomly enrolled into twelve groups of different local application parameters: group I, application pressure 2atm/application volume 1ml physiologic saline; group II, 2atm/2ml; group III, 2atm/5ml; group IV, 4atm/1ml; group V, 4atm/2ml; group VI, 4atm/5ml. The other six groups received Ringer's solution instead of saline. Administration of the solution was randomly performed in one iliac artery using the channeled balloon catheter with simultaneous balloon angioplasty (8atm). The contralateral iliac artery served as a control and was treated with balloon angioplasty only. Four weeks after local therapy, calibrated angiography was performed; the animals were sacrificed, vessel segments were excised and quantitative morphometric measurements were obtained. In none of the animals acute complications, e.g. dissection, thrombosis or perforation of the vessel, was noted. Up to an application pressure of 4atm and an application volume of 5ml, no significant neointima formation was seen compared to arteries which underwent angioplasty only. Additionally, no significant differences between saline and Ringer's solution were detected. In a multivariate analysis, neither application pressure nor volume were found to have a statistically significant influence on the amount of neointimal hyperplasia.

CONCLUSIONS

Local application of "drugs" using the channeled balloon catheter is safe and feasible without significant induction of neointimal hyperplasia compared to angioplasty, if an application volume of 5ml and a pressure of 4atm is not exceeded.

Fetal heart rate decelerations during ECT-induced seizures: is it important?

Electroconvulsive therapy (ECT) is sometimes indicated during pregnancy and may offer advantages over pharmacotherapy for the patient and the fetus (1,2). However, very little data is available on the impact of epileptic or ECT-induced seizures on the fetus. We report a case of brief fetal heart rate decelerations in a fetus associated with maternal ECT-induced convulsions.

Incomplete retention after direct myocardial injection

Direct intramyocardial injection may permit local delivery of protein and gene therapy agents for myocardial and coronary artery disease. Little is known about the immediate fate of materials administered via percutaneous endomyocardial catheters or via surgical epicardial injection. In this study, we use a novel method to evaluate the acute retention of agents injected directly into the myocardium, compare epicardial with the percutaneous endocardial and postmortem delivery, and evaluate the influence of injectate volume on myocardial retention. Fifteen 40-50 kg pigs underwent overlapping myocardial injections using a percutaneous endomyocardial catheter, an epicardial needle via an open chest, and epicardial needle postmortem. Multiple distinct 15 micro neutron-activated microsphere species were used as tracers. Two or three myocardial walls were injected in each animal using 3.5 mm, 27-28 gauge needles at varying injectate volumes. Animals were sacrificed immediately. Myocardial walls were divided and multiple microsphere species were quantified. In an additional study, nine 70 kg pigs underwent percutaneous endomyocardial injections with replication-deficient adenovirus encoding for the production of lac-Z. The injectate volume was varied, while the viral particle number remained constant. The animals were sacrificed 5 days after the percutaneous injections; the heart, liver, and spleen were collected for beta-galactosidase activity. Endomyocardial injection was associated with 43% +/- 15% microsphere retention, compared with 15% +/- 21% (P < 0.01) retention of open chest epicardial injection and 89% +/- 60% (P < 0.01) for postmortem injection. Reducing the injectate volume from 100 to 10 microL improved microsphere retention (P = 0.01). There was a trend toward improved viral transfection associated with smaller injection volumes. Despite direct intramyocardial administration, a significant fraction of injectate is not retained locally. Catheter-based needle endomyocardial injection is associated with equivalent or superior injectate retention compared with open chest epicardial injection. Proportionately, more injectate may be retained at lower volumes. Loss may involve a combination of channel leakage, venous, and lymphatic return.

Nonepileptic seizures: an overview

Since before the time of Charcot, nonepileptic seizures (NES) have intrigued and perplexed physicians. With the advent of the electroencephalogram, particularly with the addition of continuous video monitoring, the diagnosis of NES has received increasing evaluation. Characteristic historical features and clinical signs of NES, coupled with new diagnostic techniques, have progressively refined our understanding of the disorder. The treatment of patients who have NES has received much less attention and the prognosis of these patients illustrates the need for a more comprehensive, systematic, and validated intervention. These issues are discussed with an emphasis on the need for future research.

Etiology, diagnosis, and treatment of nonepileptic seizures

Psychogenic nonepileptic seizures (NES) can be classified into five categories. This review focuses on NES associated with emotional conflict, by far the most common and important group. Etiology is speculative, but the background histories of these patients are often similar. The presence of a trauma history, depression, post-traumatic stress symptoms, and the use of dissociation plus cognitive dysfunction possibly point to an organic etiology. The presentation of NES in children and adults is discussed, along with the differential diagnosis. The diagnostic differential is lengthy, with epileptic seizures of frontal lobe origin presenting a unique challenge. Diagnostic procedures are reviewed with an emphasis on the utility of hypnosis with seizure induction. Presenting the diagnosis to the patient, the role of the neurologist, and the role of the mental health consultant are reviewed. Issues in the doctor-patient relationship are also addressed, as well as the overall prognosis.

Comparative Trial of Local Pharmacotherapy withl-Arginine, r-Hirudin, and Molsidomine to Reduce Restenosis after Balloon Angioplasty of Stenotic Rabbit Iliac Arteries

PURPOSE

To determine if local application of L-arginine, r-hirudin, or molsidomine significantly reduces restenosis after balloon angioplasty in stenotic rabbit iliac arteries.

MATERIALS AND METHODS

Thirty-one male cholesterol-fed New Zealand white rabbits underwent balloon dilation of both common iliac arteries to induce arterial stenosis. Four weeks later, one stenotic iliac artery was simultaneously dilated and received local application of L-arginine (210 mg/mL, n = 7), r-hirudin (0.5 mg/mL, n = 8), or molsidomine (0.2 mg/mL, n = 8) with a channeled balloon catheter. On the contralateral side, 0.9% saline was injected as a control. In eight sham animals, saline was applied to one iliac artery and balloon dilation to only the contralateral artery. Six weeks after local treatment, vessels were harvested, and computerized morphometric and immunohistologic analyses were performed.

RESULTS

Application of drugs resulted in a significant reduction of neointimal area as follows: 53% with L-arginine (1.01 mm(2) vs. 2.17 mm(2), P <.05), 43% with molsidomine (1.04 mm(2) vs. 1.89 mm(2), P <.05), and 20% with r-hirudin (1.79 mm(2) vs. 2.24 mm(2), P <.05). Infusion of saline led to a significant increase (50%, 1.21 mm(2) vs. 1.93 mm(2), P <.05) in neointimal area compared with balloon dilation alone. Immunohistologic findings showed a significant reduction of macrophages (5.0% vs. 10.2%, P <.05) and proliferating cells (6.2% vs. 10.6%, P <.05) in the neointima after local application of L-arginine.

CONCLUSION

Reduction of neointimal area was significant for L-arginine and molsidomine but not for r-hirudin. Saline infusion caused significant arterial trauma, resulting in additional neointimal proliferation.

Transcytosis of gastrointestinal epithelial cells by Escherichia coli K1

Escherichia coli K1 is an important neonatal pathogen that is usually transferred from maternal to infant gastrointestinal tract at the time of parturition. Approximately 20% of neonates are colonized, and a proportion of colonized infants goes on to have systemic infection. Entry into the bloodstream from the gastrointestinal tract is hypothesized to occur via epithelial cell invasion. Invasion of multiple epithelial cell lines was studied using gentamicin protection assays and transcytosis of polarized monolayers. Electron microscopy was used to confirm cellular invasion. Cell lines used include two human gastrointestinal lines, Caco-2 and T84; a human respiratory cell line, A549; a human laryngeal cell line, HEp-2; and a canine kidney cell line, MDCK. A virulent E. coli K1 strain, RS218, readily invaded HEp-2, A549, and T84 cell lines in gentamicin protection assays, but was less invasive into MDCK and Caco-2 cells. RS218 also demonstrated transcytosis of both T84 and Caco-2 cells. Four clinical isolates of E. coli K1 demonstrated levels of transcytosis of T84 cells similar to RS218. Caco-2 invasiveness correlated with length of time in tissue culture with maximum invasiveness demonstrated at 11 d in culture, when cells were polarized and differentiated.

Analysis of adenoviral transport mechanisms in the vessel wall and optimization of gene transfer using local delivery catheters

Local delivery devices have been used for adenovirus-mediated gene transfer to the arterial wall for the potential treatment of vascular proliferative diseases. However, low levels of adenoviral gene expression in vascular smooth muscle cells may pose a serious limitation to the success of these procedures in the clinic. In this study, we examined the mechanisms controlling adenoviral transport to the vessel wall, using both hydrogel-coated and infusion-based local delivery catheters, with the goal of enhancing in vivo gene transfer under clinically relevant delivery conditions. The following delivery parameters were tested in vivo: applied transmural pressure, viral solution volume and concentration, and delivery time. We found that viral particles are transported into the vessel wall in a manner consistent with diffusion rather than pressure-driven convection. Consistent with diffusion, viral concentration was shown to be the key variable for viral transport in the vessel wall and thus gene expression in vascular smooth muscle cells. A transduction level of 17.8+/-3.2% was achieved by delivering a low volume of concentrated adenoviral beta-galactosidase solution through an infusion balloon catheter at low pressure without an adverse effect on medial cellularity. Under these conditions, effective gene transfer was accomplished within a clinically relevant time frame of 2 min, indicating that longer delivery times may not be necessary to achieve efficient gene transfer.

Local delivery of nadroparin via hydrogel-coated angioplasty balloon: effect on platelet deposition and smooth muscle cell proliferation--an experimental study

PURPOSE

To assess the feasibility of intravascular delivery of nadroparin, a low-molecular-weight heparin, via hydrogel-coated angioplasty balloons, and the effects of nadroparin delivered in this manner on platelet deposition and smooth muscle cell (SMC) proliferation.

MATERIALS AND METHODS

Tritiated nadroparin was used to determine the nadroparin-carrying capacity of the hydrogel-coating, kinetics of release from the balloons, and, in four pigs, delivery of the nadroparin to the iliac arterial wall. Platelet deposition in nadroparin-treated iliac arteries versus contralateral iliac arteries dilated with saline-loaded, hydrogel-coated balloons was quantified in seven pigs using 111Indium-labeled platelets. Smooth muscle cell proliferation in nadroparin and saline-treated iliac arteries in 10 pigs was evaluated 7 days after angioplasty with use of proliferating cell nuclear antigen.

RESULTS

Approximately 98 international units of nadroparin were delivered by the hydrogel-coated balloon, the majority to the angioplasty site and distal vessel. There was a trend toward decreased platelet deposition in nadroparin-treated arteries, but statistical significance was not achieved (P = .1563). Medial SMC proliferation was decreased in the nadroparin-treated arteries in nine of 10 pigs (P = .0137).

CONCLUSIONS

Hydrogel-coated balloons may be used to deliver nadroparin to the arterial wall, with measurable levels of the drug delivered to the site of angioplasty, and with resultant decrease in SMC proliferation.

Discriminating between epileptic and nonepileptic events: the utility of hypnotic seizure induction

PURPOSE

To determine the validity of the Hypnotic Induction Profile (HIP) followed by seizure induction during continuous video-electroencephalographic (EEG) monitoring to discriminate between epileptic (EE) and nonepileptic events (NEE).

METHODS

Eighty-two patients admitted to the Stanford Comprehensive Epilepsy Center for differential diagnosis of seizure-like events were evaluated. Exclusion criteria included inability or refusal to complete the HIP, lack of a "typical" event, an IQ <70, present evidence of psychosis, or a physiological cause for NEE. Sixty-nine patients met these criteria. While undergoing continuous video-EEG monitoring, the patient completed an HIP, an inventory designed to measure the degree of hypnotizability. An attempt was then made to induce the patient's typical events under hypnosis by using a split-screen technique. An event without an EEG correlate was thought to represent an NEE. A diagnosis of NEE was made independently by the neurology team and was compared with results obtained with the hypnotic evaluation.

RESULTS

Results for patients with EE were compared with those with NEE and a group consisting of both EE/NEE. All patients with NEE were then contrasted with the EE group. HIP scores for the EE patients indicated lower hypnotizability than the NEE group and were statistically significant when NEE patients and those with NEE/EE were combined. The sensitivity of seizure induction in the diagnosis of NEE was 77%, with a specificity of 95%.

CONCLUSIONS

The HIP coupled with seizure induction is a useful technique to aid in the diagnosis of patients with NEE. It is sensitive and specific, and it may provide the patient with a useful behavioral tool to control NEEs. It may also furnish a conduit for long-term treatment.

The impact of an acute pain service on postoperative pain management

An audit of postoperative pain management was conducted before and after the introduction of an Acute Pain Service (APS) run entirely by medical staff. The ability of patients to complete two pain-scoring systems, a verbal rating score (VRS) and a numerical rating score (NRS, where 0 = no pain, 10 = worst pain) was compared. We surveyed 605 adults 24 hours postoperatively. For major operations, the incidence of "severe" or "unbearable" pain at rest (VRS) over the first 24 hours decreased from 18.1% before to 3.5% after the APS (P = 0.0002) and severe/unbearable pain with movement decreased from 50% to 31% (P = 0.0037). The average NRS pain scores fell from 4.65 to 3.37 at rest (P < 0.0001) and from 6.77 to 6.19 with movement (P = 0.046). The incidence of severe/unbearable pain at rest with patient-controlled analgesia (PCA) decreased from 19.7% to 3.2% after the APS (P = 0.0012) and with movement from 51.3% to 35.1% (P = 0.049). For epidural analgesia, severe/unbearable pain at rest was 18.8% prior to the APS and 4.4% after (P = 0.14), and with movement was 43.8% before and 19.1% after (P = 0.079). The NRS pain-scoring system was unsuitable for Aboriginal or Torres Strait Islander patients. Patient satisfaction was high both before and after the introduction of the APS, and was an unreliable indicator of effective pain relief. We conclude that an APS can improve postoperative pain control with PCA and epidural analgesia.

Site-specific delivery of iloprost during experimental angioplasty suppresses smooth muscle cell proliferation

PURPOSE

The authors have previously reported that intramural delivery of iloprost during angioplasty suppresses local platelet aggregation at 1 hour in undiseased porcine arteries. In this study, the authors sought to quantify the effect of such treatment on medial vascular smooth muscle cell proliferation, an event implicated in the development of intimal hyperplasia.

MATERIALS AND METHODS

Three Yorkshire pigs underwent percutaneous transluminal angioplasty with hydrogel-coated balloons for a total of 10 iloprost-treated (experimental) and 10 saline-treated (control) arterial sites. The balloons were prepared with previously reported techniques and loaded with 2.25 microg of iloprost for the experimental sites. On the eighth day after angioplasty, these sites were harvested and prepared for immunohistochemical staining. Thin (4 microm) sections of the specimens were stained with use of monoclonal antibody to proliferating cell nuclear antigen (PCNA). Appropriate positive and negative controls were used. Approximately 350-500 vascular smooth muscle cells were randomly counted under high power (100x) by an experienced physician who was blinded to the origin of the specimen. A PCNA index (%) was calculated as follows: [(#PCNA [+] cells)/(#PCNA [+] cells + #PCNA [-] cells)]x 100. A paired t test was used for statistical comparison.

RESULTS

The PCNA indices for eight (n = 8) paired large vessels (iliac, carotid, subclavian) were 7.98 (+/- 1.8)%, for the iloprost-treated experimental sites, and 14.58 (+/- 3.8)% for the saline-treated control sites. This difference was statistically significant (P = .003). One large vessel pair was not available for analysis. When the pair of renal arteries of animal 3 were included (n = 9), the PCNA indices were 8.32 (+/- 2.3)% for the experimental sites, and 13.79 (+/- 4.2)% for the control sites. The differences were again significant (P = .01).

CONCLUSION

Intraarterial site-specific delivery of iloprost during angioplasty with drug-loaded, hydrogel-coated balloons significantly suppresses medial smooth muscle cells in swine at the expected peak period of proliferation of 7 days after angioplasty.

Mural delivery of iloprost with use of hydrogel-coated balloon catheters suppresses local platelet aggregation

PURPOSE

To develop reproducible and quantifiable methods for mural delivery of iloprost, a potent agent against platelet aggregation, with use of hydrogel-coated angioplasty balloons, and to determine the in vivo effect of direct iloprost delivery on platelet aggregation at the angioplasty site.

MATERIALS AND METHODS

Drug loading of tritiated iloprost from an immersion solution onto hydrogel-coated balloons was evaluated as a function of balloon size (3 mm x 2 cm, 6 mm x 2 cm, 8 mm x 3 cm; n = 4 each), drug concentration (0.0715 mg/mL, 0.1072 mg/mL, 0.1430 mg/mL; n = 3 each), and duration of immersion (40 seconds, 60 seconds, 120 seconds; n = 3 each). In another set of experiments, optimal drying methods were tested to minimize drug loss within a protective delivery sheath (n = 3 each). Ex vivo angioplasty was performed on excised swine arteries to estimate how much of the drug present on the balloon could be delivered to the wall (n = 3 iliac segments). Finally, in vivo angioplasty was performed in three Yorkshire pigs (n = 6 iloprost-treated and 6 control arteries) and indium-111-labeled platelet aggregation was measured at these sites, which were harvested 1 hour after the procedure.

RESULTS

In the initial set of experiments, the authors found that the volume of drug loaded is determined by the wet-volume of the hydrogel coating, that the majority of volume loading occurs within the first 2 minutes, and that the volume uptake is independent of the drug concentration. The optimal drying method resulting in the least loss of iloprost within the sheath (only 4%) was prolonged drying (5 hours) under ambient conditions. Ex vivo angioplasty experiments showed that approximately 33% of the drug present on the balloon can be delivered to the wall. Finally, in vivo experiments showed that platelet aggregation is significantly suppressed at treated sites (by approximately 33% compared to control sites; P = .03) by minuscule mural doses of iloprost (roughly estimated at under 1 microg).

CONCLUSION

Quantifiable and reproducible methods for loading iloprost onto hydrogel-coated angioplasty balloons were developed. The best of these methods was able to deliver enough iloprost into the wall to significantly reduce local platelet aggregation.

Percutaneous delivery of the gax gene inhibits vessel stenosis in a rabbit model of balloon angioplasty

OBJECTIVES

The expression of gax, an anti-proliferative homeobox gene, is rapidly downregulated in vascular smooth muscle cells (VSMCs) following arterial injury. Here we performed percutaneous adenovirus-mediated gene transfer into the iliac arteries of normal rabbits using a channel balloon catheter to assess the effects of gax overexpression on neointima formation, lumen diameter, reendothelialization and functional vasomotion.

METHODS

A channel balloon catheter was used to perform both the arterial injury and local gene delivery. In each animal both iliac arteries were randomly assigned to receive either an adenovirus expressing the gax gene (Ad-Gax) or the beta-galactosidase gene (Ad-beta gal). In a second group of animals arteries were randomly assigned to receive either Ad-beta gal or saline.

RESULTS

At one month, angiography revealed 36% less luminal narrowing in the Ad-Gax-treated arteries relative to the Ad-beta gal-treated control arteries. Histological analysis revealed that the intimal/medial ratio (I/M) was reduced by 56% in the Ad-Gax group. Endothelium-dependent vasomotion was not affected by the gax gene transfer. In the second group, no statistically significant differences were found between the saline and the Ad-beta gal-treated vessels for any of these parameters.

CONCLUSIONS

Percutaneous adenovirus delivery of the gax gene to rabbit iliac arteries following endothelial denudation and vessel wall injury reduces neointimal hyperplasia and luminal stenosis, but does not affect endothelium-dependent vasomotion. This study demonstrates that a VSMC transcription factor can potentially be utilized for the development of a molecular therapy for vascular disorders.

Feasibility and efficacy of locally delivered enoxaparin via the Channeled Balloon catheter on smooth muscle cell proliferation following balloon injury in rabbits

To determine the potential utility of local treatment of enoxaparin on restenosis, four groups of rabbits underwent balloon injury of bilateral iliac arteries with the Channeled Balloon (balloon/artery = 1.1), followed by assigned treatment (5 controls received local saline, 7 local-treatment rabbits received a one-time local delivery of 10 mg/kg of enoxaparin, 5 systemic-treatment rabbits received 10 mg/kg of enoxaparin subcutaneously once daily for 1 wk, and 5 combined-treatment rabbits received both local and systemic enoxaparin). The percentage of nuclei positive for proliferating cell nuclear antigen/microns2 of media 1 wk later was 1.97 +/- 2.01 for the control group, 2.68 +/- 2.52 for the local group, 0.22 +/- 0.32 for the systemic group, and 0.07 +/- 0.09 for the combined group (P < 0.0001 by Kruskal-Wallis test, with P < 0.05 for combined treatment group vs. controls or local treatment group and systemic vs. local groups). Feasibility study with 3H-enoxaparin showed intramural retention of 0.1-0.2% of locally delivered amount for 24 h. We conclude that one-time local delivery of enoxaparin following angioplasty is ineffective in inhibiting medial smooth muscle cell proliferation, most likely due to low efficiency. Only sustained treatment resulted in significant reduction.

Local urokinase delivery with the Channel balloon: device safety, pharmacokinetics of intracoronary drug delivery, and efficacy of thrombolysis

The Channel balloon is a new local drug-delivery catheter that has the dual capability of high-pressure lesion dilation and low-pressure drug infusion. The purpose of this study was to assess the safety and efficacy of this device in the local delivery of urokinase in the porcine model. Three in vivo protocols were performed in 57 anesthetized swine to assess the safety of Channel balloon use in the coronary vasculature, the pharmacokinetics of local urokinase delivery, and the ability of the catheter to lyse intraluminal thrombus. First, safety studies were performed in 18 coronary vessels in 13 pigs to compare angiographic and histologic changes following use of the Channel balloon with conventional balloon angioplasty. Second, intramural deposition of 123I-labeled urokinase was measured in 24 coronary arteries in 20 pigs to assess the efficiency and technical determinants of urokinase delivery and the time course of intramural drug retention. Finally, an in vivo thrombus model was used in 24 pigs to compare the thrombolytic capacity of local urokinase delivery with the Channel balloon in comparison with conventional urokinase infusion techniques. All balloon inflations and drug infusions with the Channel balloon were well tolerated in all animals without adverse angiographic, hemodynamic, or electrical sequelae. Comparative histologic studies with the Channel balloon demonstrated no additional vessel trauma beyond that seen with conventional balloon angioplasty. Between 0.09 and 0.35% of infused urokinase was intramurally deposited, with intracoronary persistence for at least 5 h. Drug infusion pressure did not significantly affect drug deposition, although larger amounts of urokinase were deposited with larger balloon:artery ratios and higher urokinase concentrations. In comparison to conventional systemic and guiding catheter infusions, local delivery of urokinase with the Channel balloon resulted in higher levels of clot dissolution. These studies have demonstrated safe intracoronary use of the Channel balloon in the porcine model. Local infusion of urokinase with this device results in significant intramural drug deposition that persists for at least 5 h. In comparison with conventional thrombolytic techniques, local urokinase delivery with the Channel balloon may result in enhanced intravascular thrombolysis.

Nucleotide sequence analysis of a gene from Burkholderia (Pseudomonas) cepacia encoding an outer membrane lipoprotein involved in multiple antibiotic resistance

Antibiotic-resistant Burkholderia (Pseudomonas) cepacia is an important etiologic agent of nosocomial and cystic fibrosis infections. The primary resistance mechanism which has been reported is decreased outer membrane permeability. We previously reported the cloning and characterization of a chloramphenicol resistance determinant from an isolate of B. cepacia from a patient with cystic fibrosis that resulted in decreased drug accumulation. In the present studies we subcloned and sequenced the resistance determinant and identified gene products related to decreased drug accumulation. Additional drug resistances encoded by the determinant include resistances to trimethoprim and ciprofloxacin. Sequence analysis of a 3.4-kb subcloned fragment identified one complete and one partial open reading frame which are homologous with two of three components of a potential antibiotic efflux operon from Pseudomonas aeruginosa (mexA-mexB-oprM). On the basis of sequence data, outer membrane protein analysis, protein expression systems, and a lipoprotein labelling assay, the complete open reading frame encodes an outer membrane lipoprotein which is homologous with OprM. The partial open reading frame shows homology at the protein level with the C terminus of the protein product of mexB. DNA hybridization studies demonstrated homology of an internal mexA probe with a larger subcloned fragment from B. cepacia. The finding of multiple antibiotic resistance in B. cepacia as a result of an antibiotic efflux pump is surprising because it has long been believed that resistance in this organism is caused by impermeability to antibiotics.

Inhibition of platelet-dependent thrombosis by local delivery of heparin with a hydrogel-coated balloon

BACKGROUND

Systemic administration of heparin can decrease mortality and morbidity of acute ischemic coronary syndromes such as unstable angina and myocardial infarction. Hemorrhage is the major limiting factor in the clinical use of systemic heparin. The objective of the present study was to determine whether local delivery of heparin could inhibit platelet-dependent thrombosis without altering systemic bleeding parameters.

METHODS AND RESULTS

Hydrogel-coated angioplasty balloon catheters were dipped in a heparin solution, dried, and applied to a platelet-rich mural thrombus in a chronic ex vivo porcine arteriovenous shunt. 111In-labeled platelet deposition was quantified by gamma camera imaging. In a separate series of experiments, 3H-heparin was used to estimate the amount of heparin delivered to the thrombus with the coated balloon. Systemic heparin administration produced a dose-dependent decrease in platelet-dependent thrombus formation that was maximal at 200 units/kg. Bleeding times and activated partial thromboplastin times were prolonged at this dose. An equal inhibition of thrombus formation was achieved after the coated balloon was dipped in a heparin solution (10,000 units/mL) and deployed at the mural thrombus. In contrast to systemic heparin administration, there was no alteration in bleeding parameters associated with local heparin delivery. The estimated amount of heparin delivered with the coated balloon was 40 units.

CONCLUSIONS

Local delivery of heparin in amounts sufficient to inhibit platelet-dependent thrombosis can be accomplished with a hydrogel-coated coronary angioplasty balloon catheter. Local heparin delivery can inhibit thrombus formation in amounts that are several orders of magnitude lower than the required systemic dose. Local delivery of heparin was not associated with prolongation of bleeding parameters.

Low-efficiency of percutaneous adenovirus-mediated arterial gene transfer in the atherosclerotic rabbit

Recombinant adenoviruses are the most efficient vectors with which to perform arterial gene transfer. Previous in vivo studies of adenovirus-mediated arterial transfection, however, have been performed using normal or endothelium-denuded arteries. It is unclear whether these results can be extended to atherosclerotic arteries. Accordingly, this study was designed to (a) assess the feasibility of adenovirus-mediated gene transfer to atherosclerotic lesions, and (b) compare the transfection efficiency, anatomic distribution of transfected cells, and duration of transgene expression achieved in normal versus atherosclerotic arteries. A recombinant adenovirus including a nuclear-targeted beta-galactosidase gene was percutaneously delivered to the iliac artery of normal (n = 25) and atherosclerotic (n = 25) rabbits. Transgene expression, assessed by morphometric as well as chemiluminescent analyses, was documented in all normal and atherosclerotic arteries between 3 and 14 d after gene transfer, but was undetectable at later time points. Transfected cells were identified as smooth muscle cells located in the media of normal arteries, and in the neointima and the vasa-vasora of atherosclerotic arteries. Two percent of medial cells, but only 0.2% of medial and neointimal cells expressed the transgene in normal and atherosclerotic arteries, respectively (P = 0.0001). Similarly, nuclear beta-galactosidase activity was higher in normal than in atherosclerotic arteries (3.2 vs. 0.8 mU/mg protein, P = 0.02). These findings indicate that atherosclerosis reduces the transfection efficiency which can be achieved with adenoviral vectors, and thus constitutes a potential limitation to adenovirus-based, arterial gene therapy.

Localized drug delivery in atherosclerotic arteries via a new balloon angioplasty catheter with intramural channels for simultaneous local drug delivery

A dual-purpose angioplasty catheter with intramural channels and exterior pores for local drug delivery ("channeled balloon") was studied in eight atherosclerotic human necropsy arteries and in 22 rabbits with atherosclerotic peripheral arteries, in which markers (0.005 microns to 15 microns) were infused locally at 2 atmospheres during simultaneous angioplasty at 6 atmospheres. Thirteen of the rabbits were sacrificed at 4 or 24 h after procedure to determine the intramural retention over time. Histology confirmed effective angioplasty and revealed presence of markers in the arterial wall in 29 of 43 treated arteries (67%), whereas all control segments without local delivery had no marker staining. majority of the ineffective local delivery (12/14) occurred when 15 micron particles were infused (12/13 arteries without intramural markers), especially when examined 4 or 24 h later. Thus, in atherosclerotic arteries, the channeled balloon enabled simultaneous local drug delivery at low pressure during effective angioplasty, although particle size may play a role in successful intramural impregnation and retention.

Arterial gene transfer to rabbit endothelial and smooth muscle cells using percutaneous delivery of an adenoviral vector

BACKGROUND

Previous investigations in live animals convincingly established that arterial gene transfer, while feasible, was compromised by a low transfection efficiency. More recent studies have shown that transfection efficiency may be substantially augmented by the use of recombinant adenoviral vectors. Most in vivo transfections reported to date, however, have used direct (operative) administration of the adenoviral vector. Clinical applications of arterial gene transfer (such as prevention of restenosis), however, would require local percutaneous delivery of the transgene. The present study was designed to extend in vivo intraoperative findings to percutaneous delivery system and to assess whether gene transfer remains site specific.

METHODS AND RESULTS

A recombinant, replication-defective adenovirus modified to include an expression cassette for nucleus-targeted beta-galactosidase was introduced into rabbit iliac arteries in vivo using either a double-balloon catheter (DBC, n = 27) or a hydrogel-coated balloon catheter (HBC, n = 27). Contralateral arteries-normal, endothelium-denuded, or sham-transfected with a control adenoviral vector-served as controls. beta-Galactosidase expression was assessed by X-Gal staining. Cell-transduction efficiency was measured by morphometric analysis. Polymerase chain reaction (PCR) and histochemistry were used to detect the presence and/or expression of viral DNA in remote organs. Transgene expression was detected in all cases (46 of 46) between 3 and 14 days after transfection but was in no case detectable 28 days after transfection. In the DBC group, transgene expression was limited to endothelial cells when the endothelium was left intact and to rare medial cells (< 2.2%) when it had been removed. In contrast, HBC delivery resulted in transduction of up to 9.6% of medial smooth muscle cells (P = .0001). Optimized PCR and histochemistry failed to detect evidence of extra-arterial transfection except in a small number of cells (between 1 in 3 x 10(2) and 1 in 3 x 10(5) cells) in the livers of 2 animals in the DBC group.

CONCLUSIONS

(1) Efficient, adenovirus-mediated, arterial gene transfer to endothelial and/or smooth muscle cells is feasible by percutaneous, clinically applicable techniques. (2) Consistent transfection of medial smooth muscle cells may be achieved when the endothelial layer is abraded. (3) Medial transfection is more efficient when an HBC, rather than a DBC, is used. (4) Percutaneous delivery of the adenoviral vector via HBC results in site-specific arterial gene transfer. Very-low-level extra-arterial transfection may occur, however, when the DBC is used.

Inhibition of platelet deposition and lysis of intracoronary thrombus during balloon angioplasty using urokinase-coated hydrogel balloons

BACKGROUND

Conventional balloon angioplasty of intracoronary thrombus is associated with a high incidence of abrupt closure, distal embolization, and no-reflow phenomenon. The purpose of this study was to assess a new technique for treating intracoronary thrombus consisting of the local delivery of urokinase directly to the angioplasty site with urokinase-coated hydrogel balloons.

METHODS AND RESULTS

We assessed local urokinase delivery using hydrogel balloons in four protocols. First, we evaluated the pharmacokinetics of urokinase delivery in vitro using 125I-labeled urokinase to measure drug loading onto hydrogel balloons, drug retention by the hydrogel polymer during blood exposure, and drug transfer from the balloon surface to the arterial wall during balloon dilatation. Second, we measured 125I-urokinase washoff from the hydrogel balloon in the intact circulation and intramural drug delivery during in vivo balloon angioplasty in 10 anesthetized New Zealand rabbits. Third, we assessed the effect of local urokinase delivery on 111In-labeled platelet deposition after balloon angioplasty in vivo in 13 porcine carotid or iliac arteries dilated with urokinase-coated balloons and compared them with contralateral control arteries dilated with saline-coated balloons. Finally, we determined the clinical efficacy of urokinase-coated balloons in 15 patients with intracoronary thrombus, including 7 who demonstrated abrupt thrombotic closure after conventional angioplasty. Between 241 and 1509 U urokinase could be loaded onto hydrogel balloons ranging in size from 2 to 8 mm. In vitro and in vivo studies demonstrated that hydrogel balloons absorbed significantly more urokinase and demonstrated less drug wash-off than nonhydrogel balloons (P < .01). Similarly, both in vitro and in vivo studies demonstrated urokinase transfer from the hydrogel to the arterial wall during balloon angioplasty, with greater intramural drug deposition with larger balloons (P < .01). Local urokinase delivery after in vivo porcine angioplasty decreased 111In-labeled platelet deposition by 47% compared with contralateral control vessels (P = .03). Use of urokinase-coated balloons in patients with intracoronary thrombus resulted in thrombus dissolution and reversal of abrupt closure in all cases, without evidence of distal embolization.

CONCLUSIONS

With the use of hydrogel-coated balloons, urokinase can be delivered locally to an angioplasty site. This technique decreases platelet deposition after in vivo balloon angioplasty and is efficacious in treating intracoronary thrombus in patients, including those with abrupt thrombotic closure.

Local delivery of an antiproliferative drug with use of hydrogel-coated angioplasty balloons

PURPOSE

To determine the feasibility of using hydrogel-coated angioplasty balloons to deliver drugs that inhibit vascular smooth muscle cell (VSMC) proliferation.

MATERIALS AND METHODS

In initial experiments, the tyrphostin RG-50872 (1 mumol/L) completely inhibited VSMC proliferation induced by platelet-derived growth factor (PDGF) in vitro when RG-50872 treatment preceeded PDGF exposure by 15 minutes. This inhibition was reversible and was not due to cell toxicity. In further experiments, hydrogel-coated and silicone-coated angioplasty balloons (2.5 mm in diameter by 20 mm in length) were coated with either 10 microL of RG-50872 (40 mmol/L in dimethyl sulfoxide [DMSO]) or DMSO vehicle, or were left uncoated. Afterward, each angioplasty balloon was inflated, submerged in 50 mL of culture media, and agitated for 2 minutes to promote drug release. Dilutions of this media were tested for their ability to inhibit VSMC proliferation.

RESULTS

All hydrogel-coated balloons (n = 5) released sufficient RG-50872 to inhibit PDGF-induced VSMC proliferation by 95% or more, whereas none of the silicone-coated balloons (n = 4) did. DMSO-treated and untreated balloons had no effect on proliferation.

CONCLUSION

These findings demonstrate that the hydrogel-coating on angioplasty balloons can take up and release sufficient RG-50872 to significantly inhibit smooth muscle cell proliferation. Further in vivo experiments are needed to determine if hydrogel-coated balloons can deliver sufficient RG-50872 to the arterial wall to affect VSMC proliferation.

Decreased platelet deposition and smooth muscle cell proliferation after intramural heparin delivery with hydrogel-coated balloons

BACKGROUND

In vitro and in vivo studies have demonstrated both anticoagulant and antiproliferative effects of heparin. The purpose of this study was to assess the effect of local intramural delivery of heparin, using heparin-coated hydrogel balloons, on platelet deposition and early smooth muscle cell proliferation after in vivo balloon angioplasty.

METHODS AND RESULTS

The effects of local heparin delivery were assessed during balloon angioplasty of porcine peripheral arteries. All balloon dilatations were performed with oversized hydrogel balloons coated with a known quantity of heparin. Balloon dilatations in contralateral vessels with uncoated hydrogel balloons served as study controls. The pharmacokinetics of heparin delivery were assessed using 3H-heparin to quantitate heparin wash-off from the balloon surface, heparin delivery to the arterial wall, and intramural persistence of drug. Platelet deposition at 1 hour after balloon injury was quantified using 111In-labeled platelets. Smooth muscle cell proliferation was assessed 6 to 7 days after angioplasty with immunohistochemical staining for proliferating cell nuclear antigen. 3H-heparin wash-off from the hydrogel balloon surface occurred rapidly, with approximately 95% of the heparin coating disappearing within 10 seconds in the intact circulation. Approximately 2% of heparin on the balloon surface was delivered intramurally at the time of angioplasty. Intramural heparin dissipated rapidly, although small amounts of intramural heparin could still be detected for at least 48 hours. In comparison to control vessels, there was less 111In-platelet deposition (P = .002) and less medial smooth muscle cell proliferation (P = .03) in heparin-treated vessels.

CONCLUSIONS

Local intraluminal delivery of heparin at the time of balloon angioplasty with heparin-coated hydrogel balloons results in intramural deposition of drug that persists for at least 48 hours. This in vivo technique significantly decreases platelet deposition and early smooth muscle cell proliferation after angioplasty injury.

Arterial gene transfer using pure DNA applied directly to a hydrogel-coated angioplasty balloon

Direct arterial gene transfer has been previously achieved using double-balloon catheters and perforated balloons, in most cases facilitated by the use of cationic liposomes or viral vectors. These gene delivery systems, however, have been compromised by issues relating to efficacy and/or safety, and furthermore require that angioplasty be performed independent of gene transfer. We investigated the possibility that arterial gene transfer might be performed during balloon angioplasty by delivery of naked genetic material from a thin coat of hydrogel polymer applied to a standard angioplasty balloon. Transfections with luciferase DNA applied to a hydrogel balloon were performed in rabbit arteries. Luciferase expression 3 days after transfection was tested in three different models: (i) an organ culture model (n = 10); (ii) surgically exposed carotid arteries (n = 14); and (iii) external iliac arteries using a percutaneous approach (n = 13). Supplementary transfections (n = 3), intended to identify the site of arterial transfection, were performed using the gene encoding for nuclear-specific beta-galactosidase (beta-gal). All rabbit arteries transfected with the luciferase gene (37/37; 100%) expressed luciferase activity. Gene expression achieved in vivo, either in the surgically exposed carotid arteries or in the external iliac arteries transfected percutaneously, was quantitatively similar to that achieved in the organ culture model. Reduction in the duration of inflation from 30 min to 1 min had no statistically significant impact on transfection efficiency. Gene expression was documented to persist up to 14 days post percutaneous transfection. Analysis of arteries transfected with nuclear-specific beta-gal showed the presence of the transgene in intimal and subintimal sites. These results demonstrate that vascular gene transfer can be performed successfully without liposomes or viral vectors using DNA applied to a standard angioplasty catheter balloon coated with hydrogel. Percutaneous transfection with a hydrogel-coated balloon permits gene transfer coincident with the angioplasty procedure itself, even with inflations as short as 1 min.

Feasibility and drug delivery efficiency of a new balloon angioplasty catheter capable of performing simultaneous local drug delivery

BACKGROUND

Local drug delivery at angioplasty treatment sites may improve acute and long-term results after angioplasty. A new dual-purpose balloon angioplasty catheter containing intramural channels and exterior pores ('channeled balloon') was designed to allow local drug delivery at low pressure without jet streams during simultaneous balloon angioplasty.

METHODS

Acute feasibility studies were performed in normal ex-vivo and in-vivo arteries (three canine arteries and three rabbits with normal iliac arteries), in which 2 ml of marker agents were locally infused at 2 atm during simultaneous angioplasty at 6 atm with the channeled balloon. Histology, radioactive counting, and autoradiography were performed to determine the intramural localization of the delivered markers. The in-vitro efficiency of acute local drug delivery was estimated in seven normal canine arteries by infusing 3H-heparin and radioactive counting.

RESULTS

Histology revealed the presence of markers in the inner third of the media in all ex-vivo samples, and markers in all in-vivo iliac arteries except for one, whereas control segments had no intramural staining. Autoradiography documented transmural radioactive granules. Radioactive counts were 40- to 263-fold higher in those locally treated with the radioactive marker agent. Efficiency of the acute local delivery was estimated by dividing the actual counts by the expected counts; it ranged from 24 to 48%.

CONCLUSION

This study demonstrates that the channeled balloon is capable of delivering drugs locally at low pressure in adequate concentrations during simultaneous high-pressure balloon angioplasty in normal arteries.