ABSTRACTWe tested a new rotational thrombectomy catheter in acute thrombi formed both in vitro and in vivo. The catheter consisted of a rounded platinum tip, 0.025 inch diameter by 0.08 inch long, attached to a flexible steel guidewire supported by an external sheath. In vitro, the force required penetrate thrombus was reduced fivefold by rotation of the catheter at 4000 rpm (0.75 + 1.2 g rotating vs 3.9 ± 2.1 g static; p < .001). Fibrin was extracted selectively from the thrombus and tightly wound about the shaft (3.8 ± 1.5 mg rotating vs 0.75 ± 0.4 mg static; p < .001). In vivo, subtotal complete thrombosis of the canine femoral artery was created. Thrombectomy by catheter rotation always produced tightly wound adherent fibrin on the catheter shaft. Angiographic patency was restored in 20 of 22 (91%) arteries, totally in seven of 22 (32%) and partially (>20% increase in lumen diameter) in 13 of 22 (59%). There was one arterial perforation (5%). We conclude that this new mechanical catheter device reduces the force required to penetrate thrombus. Additionally, by winding fibrin about its shaft, the catheter is able to selectively remove the fibrin matrix of thrombus. Thus both the ease of initial thrombus recanalization as well as physical removal of thrombus are promoted by new approach. Such an approach may be relevant to the treatment of recent thrombosis in acute myocardial infarction.