Increased phagocytosis of platelets from patients with secondary dengue virus infection by human macrophages.

The relationship between the percent phagocytosis of platelets by differentiated THP-1 cells was examined using flowcytometry and the peripheral platelet counts as well as platelet-associated IgG (PAIgG) in 36 patients with secondary dengue virus (DV) infections. The percent phagocytosis and the levels of PAIgG were significantly increased in these patients during the acute phase compared with the healthy volunteers. The increased percent phagocytosis and PAIgG found during the acute phase significantly decreased during the convalescent phase. An inverse correlation between platelet count and the percent phagocytosis (P = 0.011) and the levels of PAIgG (P = 0.041) was found among these patients during the acute phase. No correlation was found, however, between the percent phagocytosis and the levels of PAIgG. Our present data suggest that accelerated platelet phagocytosis occurs during the acute phase of secondary DV infections, and it is one of the mechanisms of thrombocytopenia in this disease.

Embolic protection devices.

The limiting factor in coronary artery bypass surgery is the relatively rapid progression of atheromatous disease in the saphenous vein grafts. Greater than one-half of these vein grafts will fail by 10 years, and the risks associated with repeat coronary artery bypass surgery are significantly greater than that of the initial surgery. Yet, catheter-based interventional treatment of saphenous vein grafts is hindered by distal embolization of friable lipidrich plaque. This is one mechanism responsible for reduced antegrade flow (i.e., "no-reflow" phenomenon), including spasm of the distal microcirculation and platelet clumping. This complication increases the risk of a major adverse clinical event (i.e., myocardial infarction or late mortality). Distal protection devices are designed to provide protection of the distal microcirculation during percutaneous intervention. One device type is a balloon occlusive system that temporarily occludes the distal vessel during the intervention followed by the aspiration of liberated atheromatous and thrombotic material before it reaches the arteriolar and capillary bed. The other device type is a nonocclusive, filter-based system that preserves coronary blood flow through tiny pores, as low as 100 microns. Atheromatous and thrombotic material is trapped in the filter-based systems and then removed with the retrieval of the device through a retrieval catheter. This article discusses the current distal protective devices.

Guiding catheter aspiration to prevent embolic events during saphenous vein graft intervention.

UNLABELLED: Percutaneous coronary interventions (PCI) in saphenous vein graft (SVG) stenosis carries 10%-20% risk of major adverse clinical events (MACE) or reduced antigrade flow (No-reflow Phenomena). The PercuSurge device is not available at all United States hospitals and sometimes anatomically cannot be placed (distal stenosis). We developed a simple technique for use in patients who could not have the PercuSurge device placed during PCI of SVG. METHODS: The basic concept of this technique is the use of guiding catheter aspiration during PCI. Over a two-year period, seven patients underwent PCI in SVG, using this technique for symptomatic stenosis. They were all males, average SVG age was 14 +/- 6 years, 43% were degenerated SVG's, four (57%) had new stents placed, and three (43%) had percutaneous transluminal coronary angioplasty (PTCA) or cutting balloon therapy. All patients were pretreated with aspirin and clopidogrel and had baseline preprocedure serum creatine kinase (CK) and ECG. Following the procedure, patients had repeat serum CK and ECG eights hours post-procedure. No patients received glycoprotein platelets inhibitors. RESULTS: Twenty to 60 mL of blood with gross macroscopic material was recovered during aspiration. None of the patients experienced no-reflow phenomena or had major elevated CKs during the procedure as defined as 5 x normal baseline. Thirty-day MACE in all patients was zero. CONCLUSION: The pilot study suggests that guiding catheter aspiration may be effective in reducing MACE is some patients undergoing PCA in SVG.