LABORATORY INVESTIGATION THROMBOLYSIS Mechanical thrombolysis: a new rotational catheter approach for acute thrombi

We 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 to 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 or 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 this new approach. Such an approach may be relevant to the treatment of recent thrombosis in acute myocardial infarction. Circulation 73, No. 5, 1006-1012, 1986. THROMB3OSIS is the precipitating event in most transmural acute myocardial infarctions. ' Recently, intense interest in chemical and mechanical means for dissolving or disrupting such thrombi has developed.26 Prior mechanical approaches to recanalization have involved simple penetration of the thrombus by a guidewire. In this study, we report a new approach to the mechanical penetration and removal of recently formed thrombi by a rotational thrombectomy catheter. Through rotation, two novel results are achieved. First, the force required to penetrate thrombus is markedly reduced. Second, the fibrin matrix of the thrombus is selectively and tightly wound about the catheter shaft. After removal of the fibrin scaffold by retraction through the catheter, the thrombus is liquefied by release of the cellular elements into the circulation. In this study, we report on thrombus penetration and disFrom the Departments of Medicine and Pathology, University of Washington and the Seattle Veterans Administration Hospital, Seattle, and Squibb Medical Systems, Bellevue, WA. Supported by the Medical Research Service of the Veterans Administration and a grant from Squibb Medical Systems. Dr. Hansen was supported by a fellowship from the American Heart Association of Washington, Seattle. Address for correspondence: James L. Ritchie, M.D., Veterans Administration Hospital, Department of Cardiology (11 1C), 1660 South Columbian Way, Seattle, WA 98108. Received Aug. 1, 1985; revision accepted Feb. 6, 1986. 1006 solution both in vitro and in vivo in the canine femoral artery. This approach may also be applicable to the coronary circulation.