Recanalization and thrombectomy of internal anastomosis in a patient with tetralogy of Fallot using the AngioJet rheolytic catheter.

The modified Blalock-Taussig shunt is the palliative treatment of choice for tetralogy of Fallot. Shunt thrombosis is a potential complication, requiring high-risk reoperation. The use of percutaneous rheolytic devices for thrombus removal in such occluded shunts has not been previously reported. We describe a case in which use of a rheolytic catheter resulted in significant thrombus removal and rapid reversal of cyanosis and dyspnea in a 5-year-old patient. The patient remains free of symptoms at 30-day follow-up.

Rheolytic thrombectomy during percutaneous revascularization for acute myocardial infarction: experience with the AngioJet catheter.

BACKGROUND: Although balloon angioplasty and stenting are effective in the treatment of acute myocardial infarction (MI), reduced coronary flow and distal embolization frequently complicate interventions when thrombus is present. Adjunctive treatment with mechanical thrombectomy devices may reduce these complications. METHODS AND RESULTS: We evaluated the angiographic and clinical outcomes of 70 patients with acute MI (16% with cardiogenic shock) and with angiographically evident thrombus who were treated with AngioJet rheolytic thrombectomy followed by immediate definitive treatment. Procedure success (residual diameter stenosis <50% and Thrombolysis in Myocardial Infarction [TIMI] flow > or =2 after final treatment) was achieved in 93.8%. Clinical success (procedure success without major in-hospital cardiac events) was achieved in 87.5%, with an in-hospital mortality rate of 7.1%. Final TIMI 3 flow was achieved in 87.7%. AngioJet treatment resulted in a mean thrombus area reduction from 73.2 +/- 64.6 mm(2) at baseline to 15.5 +/- 30.1 post-thrombectomy (P <.001). Subsequent definitive treatment included stenting in 67% and balloon angioplasty alone in 26% of patients. Procedural complications included distal embolization in six patients and perforation in two patients. There were no further major adverse events during 30-day follow-up. CONCLUSION: Rheolytic thrombectomy can be performed safely and effectively in patients with acute MI, allowing for immediate definitive treatment in thrombus-containing lesions.

Preclinical evaluation of a rheolytic catheter for percutaneous coronary artery/saphenous vein graft thrombectomy.

The presence of thrombus increases the rate of acute complications and restenosis in percutaneous revascularization of native coronary arteries and saphenous vein grafts. Rheolytic thrombectomy uses high velocity saline jets to create a Bernoulli effect for thrombus entrainment, dissociation, and evacuation of debris, providing a novel approach to the treatment of thrombotic lesions. The study objective was to determine the preclinical safety and effectiveness of a 5 French rheolytic thrombectomy catheter designed for use in coronary arteries and saphenous vein grafts. In vitro testing was performed to evaluate catheter effectiveness (clot removal rate) and safety (particle generation and hemolysis). This was followed by acute (n = 6) and chronic (n = 6) canine studies to determine hemodynamic, angiographic, and histopathologic effects of the catheter. The results showed effective clot removal with minimal embolization: 99.4% of the total clot volume was removed with only 0.1% proximal embolization and 0.5% distal embolization. 98.4% of the embolic particles were less than 10 microm. Canine studies revealed no significant angiographic, hemodynamic, histopathologic, or electrocardiographic abnormalities with the exception of transient heart block in one animal. There was transient hemolysis which normalized within 24 hours with no adverse effects. These results demonstrate the effectiveness and safety of coronary rheolytic thrombectomy and provided the basis for clinical trials to further evaluate this promising new approach for coronary thrombectomy.

Dendritic cell/lymphocyte clustering: morphologic analysis by transmission electron microscopy and distribution of gold-labeled MHC class II antigens by high-resolution scanning electron microscopy.

Dendritic cells (DCs) are potent antigen-presenting cells for a variety of immune responses; however, their mechanism of action has not been established. It is known that DCs can cluster with one another and with other cell types during in vitro immune responses, and clustering may be essential for the activation of resting lymphocytes. In this study, ultrastructural examination of clusters that form during extended culture of enriched rat splenic DCs (approximately 70% DCs) is reported. DCs were readily distinguished from other cell types, which included lymphocytes and macrophages. DCs displayed characteristic veils and/or dendritic processes that intertwined with processes of other cells within the cluster, or extended from the cluster periphery. Occasional DCs contained large vacuoles lined with small vesicles. A paramount feature of DCs is their constitutive expression of high levels of surface major histocompatibility complex class II antigens. The surface distribution of class II antigens on clustering DCs was examined using 10 nm immunogold labeling techniques and high-resolution scanning electron microscopy. DCs were readily distinguished by morphologic criteria, and examination of various surface membrane regions revealed a differential distribution of class II antigens. Gold label was frequently distributed in linear arrays and clusters, suggesting a cytoskeletal role in the recycling/redistribution of Class II antigens. These morphologic findings further an understanding of basic DC biology and their mechanism of action as antigen-presenting cells.

Comparative analysis of potency of splenic dendritic and adherent cells (macrophages) as alloantigen presenters in vivo.

Dendritic cells and macrophages have been attributed with stimulatory capacity for in vivo and in vitro immune responses. However, the relative contribution of each of these cell types has long been in dispute. Therefore, the differential ability of dendritic cells and macrophages (splenic adherent cells [SACs]) to stimulate pancreatic islet allograft rejection in reversed alloxan-induced diabetic rats was examined. Rats bearing established allografts were challenged with various dosages of donor-strain dendritic cells or SACs, and graft rejection was assessed by analysis of plasma glucose levels and/or histological criteria. Marked differences in the ability to stimulate allograft rejection were observed at the 10(5)-cell dosage; 10(5) dendritic cells induced graft rejection in five of six rats (1 rat required 2 injections), whereas 10(5) SACs failed to induce rejection in four of four rats (P less than 0.10, chi 2 test). Challenge stimuli consisting of less than or equal to 10(5) SACs or less than or equal to 10(4) dendritic cells failed to induce graft rejection. These findings indicate that dendritic cells are potent stimulator cells for in vivo immune responses. Previous studies indicated that as few as 10(3) dendritic cells initiate allograft rejection in nondiabetic recipients. That more dendritic cells were required to stimulate rejection in reversed diabetic recipients compared with nondiabetic recipients suggests that other factors, such as the diabetic state and the production of a tolerant status achieved by larger amounts of grafted tissue, may influence graft survival.