OBJECTIVE--To evaluate the safety and efficacy of a prototype temporary stent (RX Flow Support Catheter, Advanced Cardiovascular Systems) in maintaining coronary perfusion and improving vessel patency in the event of acutely compromised flow complicating percutaneous transluminal coronary angioplasty. DESIGN--Prospective clinical study as part of a multicentre trial. SETTING--Regional cardiac centre catheterisation laboratory. PATIENTS--Eight patients undergoing routine percutaneous transluminal balloon coronary angioplasty in whom coronary artery dissection resulted in impaired coronary artery flow with angina or electrocardiographic ST segment shift, needing bail-out treatment at the time of the procedure. RESULTS--The RX Flow Support Catheter was successfully used and improved coronary flow in all cases, with a reduction in luminal stenosis and resolution of symptoms. The temporary stent was expanded for an average of 85 (range 30-209) minutes. In six patients it was used as a bridge to further treatment (permanent stent in four and coronary artery surgery in two) and two patients did not need further treatment. CONCLUSION--The temporary stent was safe and effective in the acute management of coronary dissection. The main advantages are its ease and speed of use, and successful restoration of coronary flow both to the distal artery and to affected side branches pending definitive treatment.