BACKGROUND In vivo studies have shown that valves in veins are paired in an orthogonal configuration. The aim of this study is to characterize the flow interaction of paired valves under controlled in vitro bench conditions. METHODS A bench top in vitro experiment was set up at physiological flow conditions to simulate the flow inside a venous valve. Two bicuspid bioprosthetic valves paired i...

The Doppler echocardiographic characteristics of 70 prosthetic valves in 35 patients are reported. Twenty nine patients had a Björk-Shiley prosthesis in both mitral and tricuspid positions and six had Carpentier-Edwards valves in both sites. Five of the patients had abnormal tricuspid prostheses on the basis of clinical and echocardiographic criteria. Pulsed wave Doppler echocardiography was us...

Conventional electro-hydraulic precision motion control systems are controlled by either servo valves or proportional directional control valves. Neither of the valves are able to control the pressures at the two cylinder chambers independently or to use the regeneration flow. The result is that while precision motion control is possible, significant energy saving is not. In order to save energ...

2542 B ioprosthetic valves are increasingly used in patients with aortic stenosis. Compared with mechanical valves, bio-prosthetic valves are associated with a lower risk of thrombo-embolic events and do not require long-term anticoagulation. 1,2 However, bioprosthetic valves have limited durability; the best current valves can be expected to degenerate within 10 to 20 years, resulting in steno...

In this rebuttal, I will provide an empirically supported deconstruction of Dan’s primary lines of reasoning, in order to assess the validity of his underlying assumptions. My goal in presenting this counter-perspective is not to push back against Dan (in fact, I appreciate the discussion he has stimulated as a “devil’s advocate”), but rather to give fellow advisors a framework for assessing th...