Prolonged intracoronary urokinase infusion for acute stent thrombosis

Stent placement is effective on both postoperative hepatic arterial pseudoaneurysm and subsequent portal vein stricture: A case report

To treat postoperative bleeding after hepato-pancreato-biliary surgery, interventional radiology has become essential. We report a case of coincidental pseudoaneurysm and jejunal varices that were both successfully treated by stent-grafts. After a pancreaticoduodenectomy, the patient developed a pseudoaneurysm in the hepatic artery and a stenosis in its periphery. After establishing hepatic arterial flow by placing stent-grafts over both the pseudoaneurysm and the stenosis, the pseudoaneurysm was embolized with microcoils. Nine months later, the patient developed jejunal varices caused by a severe stricture in the main trunk of the portal vein. Percutaneous transhepatic portography was performed and stent-grafts were placed over the stenotic segment. A venoplasty using stent-grafts normalized the portal blood flow and the jejunal varices vanished. Although stenosis occurred due to scarred tissues from leakage after pancreaticoduodenectomy, stent-grafts were useful for managing jejunal bleeding post-operatively.

Stent thrombosis in a patient receiving chemotherapy

Intravascular stents are successfully used during coronary revascularization. Subacute stent thrombosis is a rare complication, associated with a 40-60% risk of myocardial infarction, and occurs 5-10 days after implantation. We describe a case of late stent thrombosis potentially due to delayed endothelialization from cancer chemotherapy.

Porcine model of stent thrombosis: platelets are the primary component of acute stent closure

Acute stent thrombosis remains a major concern of coronary stent implantation. Animal studies using stents do not adequately mimic this clinical problem, since stent placement is rarely associated with acute closure. The purpose of this study was to develop and characterize a porcine model of stent thrombosis. Improved understanding through such a model may be useful toward preventing and treating acute stent closure. Whole blood was drawn from domestic crossbred swine one day before study. Platelets were isolated, labeled with 111-In tropolone, and reinjected within 18 hr of the study. Bilateral carotid arteries were exposed, and severe injury induced by a series of mechanical crushes. This method produced histologic injury similar to human coronary angioplasty, with medial disruption and large dissections protruding into the lumen. Stenting was performed in standard fashion with 3.5-mm JJIS stents. Local platelet deposition was measured and recorded as 111-In radioactivity using a miniaturized scintillation detector (Dosimeter Corp.) mounted directly at the artery injury site. This measurement was made in real time at 1-min intervals. Similarly, volumetric blood flow was measured in real time by Doppler flowmeter. Eighteen arteries of nine pigs were studied. In nine arteries from nine pigs, crush injury only was performed and monitored. In the contralateral artery, crush injury was followed immediately by placement of a 3.5-mm Palmaz-Schatz (coronary) stent. Blood flow decreased rapidly following injury in both groups and followed a cyclic pattern. Eight arteries of the crush alone and two arteries of the crush plus stent groups were totally occluded 1 hr after crush. 111-In counts normalized to baseline were significantly higher at 1 hr in both groups compared to baseline; in the stented group, counts were higher than in the unstented group. Blood flow was higher in the stented group than in unstented group for 1 hr. Histopathologic observation of the thrombi forming in both crush-only and crush-stent injuries showed severe medial dissections with obstructing medial flap formation. The thrombi forming in both groups were highly platelet rich. This model of stent and arterial thrombosis showed rapid formation of platelet-rich thrombus, cyclic blood flow variations, and acute occlusion in 20% of cases. Stent placement at arterial injury sites is associated with thrombus that is predominantly platelet rich. Stent placement at injury sites enhances platelet deposition over crush injury alone. Despite greater numbers of platelets, as shown by increased 111-In counts, stenting improved vessel patency. These were likely due to higher volumetric blood flow, continuous deposition, and embolization of labeled platelets.

Treatment of acute stent thrombosis with local urokinase therapy using catheter-based, drug delivery systems: a case report

Abrupt thrombotic stent closure remains a difficult problem to treat in the cardiac catheterization laboratory. A 63-yr-old white female initially underwent successful placement of a Palmaz-Schatz biliary stent in the proximal RCA following failed coronary angioplasty. One week later, the patient represented with an acute inferior infarction and thrombotic occlusion of the stent site in spite of adequate anticoagulation. A new, local drug infusion catheter (the Dispatch catheter) was placed at the angioplasty site and 150,000 units of urokinase were locally infused, with immediate restoration of normal distal flow and a subsequent marked decrease in angiographic thrombus. A small, residual thrombotic filling defect was further treated with a urokinase-coated hydrogel balloon (Hydro Plus). Following local urokinase delivery with the Dispatch catheter and hydrogel balloon, there was complete resolution of angiographic thrombus with TIMI 3 flow and no evidence of distal embolization or no-reflow. Local urokinase delivery directly to the site of thrombus with catheter-based drug delivery systems may be a useful technique for rapidly lysing intracoronary clot and re-establishing coronary flow in the setting of acute stent thrombosis.