Collateral flow and restenosis: appreciating hydraulics and outcomes of percutaneous coronary intervention.

methods (balloons with jets, leaks or even needles, coated stents, etc.) are too rough for the tiny endothelial and subendothelial tissues. Despite reports about the feasibility and safety of different local drug delivery devices, their clinical effectiveness has yet to be proved. Increased risk of arterial thrombosis after local delivery of some drugs is one major issue, but probably the most important limitation is the greater extent of tissue injury by local drug delivery devices. This additional injury may stimulate more neointimal hyperplasia and thus counterbalance the potential benefit of locally delivered drug. The fight against restenosis is a 20-year viscious circle. Up to now, local intracoronary drug delivery seems not to have broken this circle. New, entirely different approaches — intrapericardial drug delivery, radioactive stents and intracoronary radiation therapy may help break this circle in near future. P. WIDIMSKYu Cardiocenter University Hospital Vinohrady, Prague, Czech Republic