A thrombus can be removed mechanically or dissolved chemically. Dissolving it means using a drug that breaks down fibrin. Those drugs cause bleeding wherever else a clot happens to be doing useful work. Given into a vein, the dose needed to clear a leg or a lung puts the whole patient at risk.
Catheter-directed thrombolysis narrows that exposure. The drug is delivered inside the clot itself, so a much smaller dose achieves a much higher local concentration. Systemic levels stay low. The technique is used for acute limb ischaemia, for extensive deep vein thrombosis, and for pulmonary embolism. It typically runs over many hours, with the patient monitored closely. Bleeding remains the principal risk throughout.
Delivery along the whole clot is what makes it work. Infusing at a single point treats only the near end. The operator would then have to reposition repeatedly as that end cleared. A perforated segment laid through the thrombus treats it all at once. That is why multi-sidehole catheters displaced single-hole ones here. Two things then determine whether the drug goes where intended. The tip must be sealed, or the agent runs out of the end and past the clot. The segment must also be positioned accurately across the thrombus. That is why these catheters conventionally mark each end of the perforated section with a radiopaque band.
Infusion typically continues overnight, with repeat imaging afterwards to judge whether enough clot has cleared. A second run is sometimes needed. Medigear.uk supplies the instructions for use with every order.