Echocardiography has become within the last years the main tool in the evaluation of the valvulopathies. Surgery plays a key role in the management of the valvular disorders, but it must be underlined that the surgical timing, planning and indication are all widely based on echocardiography. All the guidelines use the echocardiographic criteria to manage the valvular patients. Echocardiography ...

Medical and engineering technologies have developed the surgical simulators, which allow users to train for surgical skills. To perform the aortic valve replacement, which is one of the cardiovascular surgeries, it is necessary to examine not only the timing of the heart pulsating but also the stress distribution on the aortic valve. For pre-operative planning, we have visualized the stress on ...

CHEST, 77: 3, MARCH, 1980 obstructive hypertrophic cardiomyopathy and discrete subaortic stenosis, since this abnormality is seen commonly in both conditions. As pointed out by Dr. Glaser, a recent article by Krajcer et al describes a consistent difference in the timing of midsystolic closure of the aortic valve: in each of 22 patients with obstructive hypertrophic cardiomyopathy, midsystolic a...

Survival in young adult patients after mechanical aortic valve replacement is reported to be significantly reduced compared with the general ageand gender-matched population, whereas survival after the Ross procedure is excellent and comparable to that in the general population. There is ongoing debate about whether the excellent survival rates observed in Ross patients are a consequence of a h...

This paper presents a model of an electric variable valve timing (EVVT) system and its closed-loop control design with experimental validation. The studied EVVT uses a planetary gear system to control the engine cam timing. The main motivation of utilizing the EVVT system is its fast response time and the accurate timing control capability. This is critical for the combustion mode transition co...

The association of early systolic sounds with aortic valve disease has long been recognized (Potain, 1900; Oria's and Braun-Menendez, 1939). The genesis of this sound and indeed the timing in relation to aortic valve opening has been disputed. Some authors (Wolferth and Margolies, 1945; Wiggers, 1949; Minhas and Gasul, 1959) suggest that they occur at the time of aortic valve opening, while oth...

OBJECTIVES N-terminal B‑type natriuretic peptide (NT-proBNP) is an important biomarker for the detection of heart failure. Adults with congenital heart disease (ACHD) and a prosthetic heart valve are at risk for heart failure. This study aimed to determine the value of NT-proBNP in ACHD patients with a prosthetic valve and investigate its relationship with cardiac function and exercise capacity...

Research has shown that variable valve timing (VVT) can improve significantly the performance of internal combustion (IC) engines, including higher fuel efficiencies, lower emissions, and larger torque outputs at each point of the engine map. To achieve independent and continuous VVT for each valve, an electromechanical valve drive (EMV) system was proposed previously, whose feasibility with lo...

BACKGROUND Normal left ventricular myocardium demonstrates distinct spikes in the velocity trace before and after left ventricular ejection. We tested the hypothesis that the preejection and postejection velocity spikes reflect early systolic shortening and late systolic lengthening that are interrupted by mitral and aortic valve closure, respectively. METHODS AND RESULTS In 11 anesthetized d...

Substantial improvements in engine fuel e ciency torque and reduction of emissions are available with cam less actuation capable of continuous control of engine valve lift duration and timing A phenomenological model has been developed for an unthrottled operation that is key to e ciency gain An adaptive nonlinear controller has been designed to coordinate intake valve lift and duration by usin...