The concept/phenomenon of valve prosthesis/patient mismatch (VP–PM), described in 1978, has stood the test of time. From that time to 2011, VP–PM has received a great deal of attention but studies have come to varying conclusions. This is largely because of the determination of prosthetic heart valve area [called effective orifice area index (EOAi)] by projection rather than by actual measureme...

This study proposes both replenishing type and leaking type valve-pump parallel controlled systems, and then establishes their mathematical principle models and simulated numerical models. Comparative analysis of performances and parameters of the pump controlled system and valve-pump parallel controlled system indicate that the proposed systems can respond faster with high efficiency than the ...

Standard echocardiographic evaluation of aortic stenosis (AS) severity includes measurement of aortic velocity, mean transaortic pressure gradient, and continuity equation valve area. Although these measures are adequate for decision making in most patients, there is no single value that defines severe stenosis. Aortic stenosis affects not just the valve, but the entire vascular system, includi...

Valve surgery is very different from coronary artery bypass grafting (CABG). Over the natural history of valvular heart disease (VHD), the physiologic characteristics change markedly and, in the operating room, physiologic and hemodynamic conditions are quite variable and are readily influenced by anesthetic interventions. For some types of valve lesions it can be relatively difficult to predic...

To increase the efficiency of hydraulic systems by eliminating valve throttling losses, a direct displacement open circuit is proposed to control a single rod hydraulic actuator. The circuit provides three control inputs, including the displacement of a variable displacement pump, the opening area of a proportional valve, and the position of a directional valve. Pump control has a low bandwidth...

OBJECTIVES We studied the rate of thromboembolism in patients undergoing bioprosthetic replacement of the aortic or mitral valve, or both, at serial intervals after operation and the effects of anticoagulant or antiplatelet treatment and risk factors. BACKGROUND Thromboembolism appears to occur early after operation, but the incidence, timing and risk factors for thromboembolism and the role,...