Polyvinyl Alcohol:

Don’t Forget About Me!

Keigo Osuga, MD, PhD Department of Diagnostic and Interventional Radiology, Osaka University Graduate School of Medicine

Keigo Osuga, M.D., Ph.D. • No relevant financial relationship reported

PVA Products in Our Life  Synthetic polymer  Biocompatible  Chemical resistant  Elastic and tensile  Water-soluble

Cleaning sponges

Drying towel

Textile fiber

Glue

Chemical Structure • n+m = Degree of polymelization • n/n+m = Degree of saponification

Hydroxyl group (Hydrophilic) Acetate group (Hydrophobic)

 PVA is obtained by first polymerizing vinyl acetate, and second by saponification of polyvinyl acetate.  The extent of hydroxylation determines the physical, chemical and mechanical properties of PVA.

Formalized PVA

 Most PVA embolic particles undergo formalization to bridge between hydroxyl groups to give insolubility, and can be used as a permanent embolic material.  Contour® PVA, Contour SE™, Cook Medical® PVA

PVA for Medical Applications  Non-implant devices  Surgical sponges  Soft contact lenses  Eye drops  Implantable devices  Artificial cartilage  Patch grafts in cardiac surgery  Skin grafts in burns  Embolic agents

Early History of PVA as Embolic  Compressed PVA plug as a closure of PDA Porstmann W, et al. Radiol Clin North Am 1971

Early History of PVA as Embolic  Compressed PVA plug as a closure of PDA Porstmann W, et al. Radiol Clin North Am 1971

 Compressed PVA sponge for postsurgical pelvic bleeding, vascular tumors and spinal AVM Tadavarthy SM, et al. Radiology 1974 Tadavarthy SM, et al. AJR 1975

PVA plug in pre-loaded polyethylene tubes for gas sterilization

Early History of PVA as Embolic  Compressed PVA plug as a closure of PDA Porstmann W, et al. Radiol Clin North Am 1971

 Compressed PVA sponge for postsurgical pelvic bleeding, vascular tumors and spinal AVM Tadavarthy SM, et al. Radiology 1974 Tadavarthy SM, et al. AJR 1975

 PVA shavings for hypervascular tumors and AVMs Herrera M, et al. Radiology 1982

Rotating rasp to prepare shavings from PVA block

Vibrating sieve for separating shavings into different sizes

Non-spherical PVA Products  Ready-to-use dry particles  Contained in a sterilized vial  Color-coded vials according to size (50-1,200 μm)

Contour

PVA Bearing nsPVA

A PVA Particle in Microscope Dry

In contrast

 Irregular shape  Size increases in contrast by 20-40%  Rarely, small fragments