Liquid embolic agents such as ethylene vinyl alcohol copolymer (EVOH) formulations are dissolved in dimethyl sulfoxide, or DMSO, a solvent that keeps the polymer in liquid form until it is injected into the target vessel. This solvent is highly effective at its job, but it is also chemically aggressive toward many common plastics — which means the microcatheter used to deliver a liquid embolic agent cannot be an ordinary catheter. DMSO-compatible microcatheters are purpose-built devices, and understanding why materials matter here helps explain a critical safety layer in liquid embolic procedures.
Why Is DMSO So Demanding on Catheter Materials?
DMSO is a powerful solvent capable of dissolving or degrading many polymers used in standard catheter construction, including some materials commonly used in general-purpose microcatheters. If an incompatible catheter is used to deliver a DMSO-based liquid embolic, the solvent can compromise the catheter's structural integrity during the injection, potentially leading to catheter rupture, material failure, or unpredictable embolic delivery. This risk is precisely why DMSO-compatible microcatheters exist as a distinct device category, engineered specifically to withstand prolonged solvent exposure during injection.
What Materials Make a Microcatheter DMSO-Resistant?
DMSO-compatible microcatheters are typically constructed using solvent-resistant materials for the catheter's inner lining and outer jacket, such as polytetrafluoroethylene (PTFE) for the inner lumen, combined with a reinforced shaft design that maintains its integrity when exposed to DMSO over the duration of a liquid embolic injection. The catheter's hub and any connecting components must also be rated for DMSO exposure, since the entire delivery pathway is in contact with the solvent during the procedure.
How Does Catheter Design Affect Injection Control?
Beyond solvent resistance, the physical design of a DMSO-compatible microcatheter influences how precisely an operator can control the injection of liquid embolic material. A variable-stiffness shaft — softer at the distal tip for navigating small, tortuous vessels, and stiffer proximally for pushability and control — helps the catheter reach distal targets while still transmitting the operator's injection technique accurately. Reinforcement, such as a stainless-steel braid extending through much of the shaft, supports kink resistance during navigation through tortuous vascular anatomy without compromising the inner lumen's compatibility with the solvent.
What Role Does Distal Tip Design Play?
The distal segment of a DMSO-compatible microcatheter often incorporates a variable-pitch coil or similar reinforcement near the tip to maintain kink resistance in tight turns while preserving flexibility for navigation into small distal vessels. A hydrophilic coating on the outer surface is commonly used to reduce friction as the catheter is advanced through the vascular system, and tungsten-based markers near the tip aid visualization under fluoroscopy so the operator can confirm precise positioning before beginning the liquid embolic injection.
Why Does This Matter Beyond Liquid Embolics?
While DMSO compatibility is specifically relevant to liquid embolic delivery, the same microcatheters are often designed to also accommodate embolization coils, mechanical embolic devices, and contrast injection, making them versatile tools within a single embolization procedure. This multi-purpose design means operators do not necessarily need to exchange catheters if a procedure plan shifts between different embolic agents, provided the catheter selected is appropriately compatible and sized for the anatomy.
MicroDELIVERY Embolization Catheter
INVAMED manufactures the MicroDELIVERY Embolization Catheter, a microcatheter built with a composite variable-stiffness shaft, stainless-steel braid reinforcement extending through the proximal shaft, a triple-layer Pebax outer sheath, and a PTFE inner lining, designed for compatibility with DMSO-based liquid embolic agents in addition to coils and other mechanical embolic devices. Full specifications are available on the MicroDELIVERY Embolization Catheter product page. Availability and indications vary by country, and the Instructions for Use (IFU) should always be consulted.
Device availability and regulatory status vary by country. Please contact INVAMED or your authorized local distributor for current regulatory information applicable to your region.