The Effect of Mechanical Agitator Geometry on Catheter Directed Thrombectomy

Venous thromboembolism (VTE) is a vascular disease in which a blood clot forms inside of a vein, most often deep in the legs, groin, or arm. Two types of VTE exist, deep vein thrombosis (DVT) and pulmonary embolism (PE). DVT occurs when a clot in a deep vein forms, risking embolism and causing swelling as the clot obstructs blood flow. An embolism occurs when a part or all the thrombus breaks off and travels in the circulation, getting lodged in the lungs. A pulmonary embolism is a very serious medical condition and can be fatal if not treated immediately. Current guidelines for treatment recommend oral administration of blood thinners, but in cases where alternative measures are needed, intervention with catheter directed thrombolysis (CDT) is commonly attempted. Methods for catheter directed thrombolysis vary greatly, but a regular feature is the option for mechanical agitation. The most commonly seen mechanic for mechanical agitation involves an expanding mesh geometry that is expanded either behind or within the thrombus. The issue with mesh geometries lies in the delicate cell lining of the vessel. Any injury to the vessel lining can cause the recurrence of a VTE as a post treatment complication. Mesh geometries risk breakage, and the expanding radial size can risk contact with the vessel lining. To overcome this disadvantage, we present a novel design for mechanical agitation in catheter directed thrombolysis. In this novel method, a rail mounted fin geometry that is constrained to the centerline is advanced and retracted through a sample thrombus to break up the thrombus and restore flow through the vessel. To this end to study this geometry performance, three performance objectives were outlined. The objectives were peak penetration force, average forward movement force, and average mass of sample removed. 3D printed geometries varying in two angles were tested on porcine thrombus samples for the three objectives. Results suggest that the angle of pitch relative to the front face of the geometry, is very impactful on penetration and forward movement

The Surgical Release of Dupuytren's Contracture Using Multiple Transverse Incisions.

Dupuytren's contracture is a condition commonly encountered by hand surgeons, although it is rare in the Asian population. Various surgical procedures for Dupuytren's contracture have been reported, and the outcomes vary according to the treatment modalities. We report the treatment results of segmental fasciectomies with multiple transverse incisions for patients with Dupuytren's contracture. The cases of seven patients who underwent multiple segmental fasciectomies with multiple transverse incisions for Dupuytren's contracture from 2006 to 2011 were reviewed retrospectively. Multiple transverse incisions to the severe contracture sites were performed initially, and additional incisions to the metacarpophalangeal (MCP) joints, and the proximal interphalangeal (PIP) joints were performed if necessary. Segmental fasciectomies by removing the fibromatous nodules or cords between the incision lines were performed and the wound margins were approximated. The mean range of motion of the involved MCP joints and PIP joints was fully recovered. During the follow-up periods, there was no evidence of recurrence or progression of disease. Multiple transverse incisions for Dupuytren's contracture are technically challenging, and require a high skill level of hand surgeons. However, we achieved excellent correction of contractures with no associated complications. Therefore, segmental fasciectomies with multiple transverse incisions can be a good treatment option for Dupuytren's contracture

Iron construction and transformation of architectural ideals in nineteenth century France, 1830-1889

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture and Planning, 1996.Includes bibliographical references (leaves 317-339).This dissertation investigates the transformation of architectural ideals brought about by the development of iron construction during the nineteenth century in France. The emergence of iron construction paralleled the crisis of neoclassicism, in which an ambiguous compromise between classical formal norms and modem science and technology was already manifest in the iron reinforced lintel. In the crisis of neoclassicism, iron, with its impact on both technological and formal aspects of architecture, emerged as a symbolic material to create a new style of modem architecture among utopians and rationalists. However, iron construction could not create a new style on its own; nor did there exist absolute formal aesthetic principles to impose on the construction. This is a fundamental dilemma of modem architecture, an inherent contradiction of bourgeois culture. Structural rationalists during the second half of the nineteenth century tried to resolve this contradiction by attempting to create a new style of architecture based on material and constructional rationality and reason. However, their inability to create a new style was finally proved in the last decade of the nineteenth century when the Art Nouveau exploitation of iron became a passion for individual fantasies, while engineers declared the triumph of their iron construction. Subsequent rationalists' change of the material signifier of architectural modernity from iron to reinforced concrete testified to the fundamental gap between technology and form, and the dilemma of bourgeois rationalism. Early twentieth century modernist historians rediscovered nineteenth century iron construction as a precursor of modem architecture, constructing an evolutionary history of modem architecture based on the rationalist constructive tradition, from iron construction to reinforced concrete architecture. However, their "discovery" of iron construction was purely an aesthetic invention of the twentieth century based on modernist avant garde aesthetics. Behind their apparent reconciliation of modem technology and architecture lay the aestheticization of material and construction, and the subjectivization of architecture. Thus, this dissertation analyzes the displacement of architectural discourses on iron construction from an objective construction to a subjective aesthetics. This shift characterized the further development of modem architecture and its mode of existence in modem society in relation to the development of modem technology.Sanghun LeePh.D