ABSTRACT Stringent NOx and particulate emission constraints require high levels of exhaust gas recirculation. In this paper we model and analyze a Variable Valve Timing methodology that in steady-state achieves large levels of internal Exhaust Gas Recirculation (iEGR) or residual charge in Compression Ignition Direct Injection (CIDI) engines. Current external Exhaust Gas Recirculation (eEGR) te...

Aortic stenosis is the most frequent valvular heart disease. In aortic stenosis, therapeutic decision essentially depends on symptomatic status, stenosis severity, and status of left ventricular systolic function. Surgical aortic valve replacement or transcatheter aortic valve implantation is the sole effective therapy in symptomatic patients with severe aortic stenosis, whereas the management ...

The timing of surgery for chronic severe mitral regurgitation (MR) in asymptomatic patients with normal left ventricular (LV) function remains controversial. On the one hand, the natural history of chronic severe MR indicates a high likelihood of eventual progression to symptoms or LV dysfunction (1–3). In addition, hemodynamic compensation may allow LV size and ejection fraction to remain norm...

Introduction The timing of valve surgery in asymptomatic patients with significant aortic regurgitation can be challenging. Current indications focus on symptoms and left ventricular (LV) dilation/dysfunction, but prognosis is already reduced by this time. Quantification of the regurgitation has not previously been used to guide management, likely due to the difficulty of achieving this with ec...

Although infective endocarditis is primarily treated conservatively with antimicrobial therapy, early surgical intervention is often mandatory when various complications arise. These include intractable heart failure, persistent uncontrollable infection, large mobile vegetations, peripheral embolism and prosthetic valve endocarditis. Optimal timing of surgical intervention in patients with infe...

The objective of this study is to describe the mechanism of production of the first heart sound (S). The temporal relation between the major components of S, and (1) cessation of flow across the mitral valve, (2) closure of the valve, and (3) time of peak rate of rise of left ventricular pressure (peak LV dP/dt), were investigated in open-chest dogs. Phasic flow across the mitral valve was reco...

In conventional internal combustion (IC) engines, engine valve displacements are fixed relative to crankshaft position. If these valves are actuated as a variable function of crankshaft angle, significant improvements in fuel economy can be achieved. Existing electromagnetically actuated variable-valve-timing (VVT) systems characteristically use springs to provide the large inertial power to mo...

The appropriateness and timing of mitral valve surgery in patients with advanced heart failure and severe mitral regurgitation remains controversial. Recent surgical results provide evidence for beneficial effects on left ventricular remodeling and functional capacity. Given the absence of randomized trials comparing the outcomes of mitral valve surgery to medical therapy, however, clinical dec...