Alterations in Coronary Blood Flow and the Risk of Left Ventricular Distension in Venoarterial Extracorporeal Membrane Oxygenation.

Previous theoretical studies have suggested that veno-arterial extracorporeal membrane oxygenation (VA-ECMO) ought to consistently result in markedly increased left ventricular (LV) intracavitary pressures and volumes because of increased LV afterload. However, this phenomenon of LV distension does not universally occur and occurs only in a minority of cases. We sought to explain this discrepancy by considering the potential implications of VA-ECMO support on coronary blood flow and consequently improved LV contractility (the "Gregg" effect), in addition to the effects of VA-ECMO support upon LV loading conditions, in a lumped parameter-based theoretical circulatory model.

Experimental Investigation of the Anisotropic Mechanical Response of the Porcine Thoracic Aorta.

Knowledge of the mechanical properties of blood vessels and determining appropriate constitutive relations are essential in developing methodologies for accurate prognosis of vascular diseases. We examine the directional variation of the mechanical properties of the porcine thoracic aorta by performing uniaxial extension tests on dumbbell-shaped specimens cut at five different orientations with respect to the circumferential direction of the aorta. Specimens in all the orientations considered exhibit a nonlinear constitutive response that is typical of collagenous soft tissues.

Structure-Processing-Property Relationships of 3D Printed Porous Polymeric Materials.

Imparting porosity to 3D printed polymeric materials is an attractive option for producing lightweight, flexible, customizable objects such as sensors and garments. Although methods currently exist to introduce pores into 3D printed objects, little work has explored the structure-processing-property relationships of these materials. In this study, photopolymer/sacrificial paraffin filler composite inks were produced and printed by a direct ink writing (DIW) technique that leveraged paraffin particles as sacrificial viscosity modifiers in a matrix of commercial elastomer photocurable resin.

Segmental Variations in the Peel Characteristics of the Porcine Thoracic Aorta.

Aortic dissection occurs predominantly in the thoracic aorta and the mechanisms for the initiation and propagation of the tear in aortic dissection are not well understood. We study the tearing characteristics of the porcine thoracic aorta using a peeling test and we estimate the peeling energy per unit area in the ascending and the descending segments. The stretch and the peel force per unit width undergone by the peeled halves of a rectangular specimen are measured.