Regional and arterial localization of radioactive microparticles after local delivery by unsupported or supported porous balloon catheters

• Published in: The American heart journal 1995-05, Vol.129 (5), p.852-859
• Main Authors: Wilensky, Robert L., March, Keith L., Gradus-Pizlo, Irmina, Schauwecker, Donald, Michaels, MaryBeth, Robinson, Janine, Carlson, Kathy, Hathaway, David R.
• Format: Article
• Language: English
• Subjects: Angioplasty, Balloon; Animals; Arteries - diagnostic imaging; Arteries - metabolism; Arteriosclerosis - metabolism; Arteriosclerosis - therapy; Biological and medical sciences; Cardiovascular system; Catheterization - instrumentation; Catheterization - methods; Cerium Radioisotopes - administration & dosage; Cerium Radioisotopes - pharmacokinetics; Drug Delivery Systems - instrumentation; Drug Delivery Systems - methods; Equipment Design; Gamma Cameras; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Microspheres; Porosity; Rabbits; Radionuclide Imaging; Radionuclide investigations; Recurrence; Time Factors; Tissue Distribution
• ISSN: 0002-8703; 1097-6744
• DOI: 10.1016/0002-8703(95)90103-5

Catheter-mediated intramural delivery of pharmaceutical agents after angioplasty is a potential method to reduce postangioplasty restenosis. The efficacy of such delivery has been limited both by an incomplete initial intramural deposition of delivered agents and by rapid diffusion of soluble agents from the site of delivery. The local delivery of microparticulate agents results in prolonged retention of material at the delivery site. Accordingly this study was designed to evaluate the complementary issue of the initial delivery efficiency and pattern of localization of microparticles after local catheter-mediated delivery with two types of porous balloons. These two types were a “standard” porous balloon (PB) in which hydraulic pressure both inflated the balloon and infused the agents and a porous balloon with a mechanical undergirding that permitted mechanical expansion (PB/ME) before agent infusion. Radioactive cerium 141-labeled microparticles (11.4 μm diameter) were locally delivered into atherosclerotic rabbit femoral arteries after angioplasty to test the hypothesis that use of the PB/ME apparatus would yield enhanced intramural particle deposition and decreased systemic administration by increased balloon-wall contact before microparticle infusion. Six animals underwent infusion with the PB catheter, and seven animals underwent infusion with the PB/ME catheter. An image of the in vivo particle distribution was obtained with a gamma camera during infusion, immediately after infusion, and 1, 3, and 7 days after infusion. Tissue samples from the artery, periadventitia, thigh, calf, and foot musculature, and liver were obtained at animal death, and retained radioactivity was measured with a well counter. Microparticle delivery was evaluated according to two parameters: (1) the fractional regional delivery, which is the fraction of microparticles delivered into the region surrounding the balloon in the upper leg as measured by the γ camera, and (2) the fractional intramural delivery, which is the fraction of microparticles specifically delivered into the vascular tissue as measured by direct tissue counting. The fractional regional delivery was 99.9% ± 0.1% with the PB/ME and 84.2% ± 4.2% with the standard PB ( p = 0.008). Distal delivery of microparticles was accordingly lower after infusion with the PB/ME catheter; radioactivity at 7 days in the foot averaged 9 ± 4.5 counts/min/mg tissue versus 186 ± 67 counts/min/mg after infusion with the PB cathete