Heart failure is a great threat to human health. When conventional drug treatments have limitations and transplantation confronts problems of immunoreaction and lacking donors, the ventricular assist device (VAD) has irreplaceable importance. The VAD substitutes total or part of the heart as a blood pump by using mechanical or biologicmechanical method. Since its clinical application from the 1960s, after a long time of research and application practice, it has been applied to postoperative cardiovascular recovery, heart transplantation and replacement, myocardiac recovery and permanent therapy for heart failure. In the future, VAD will develop toward such characteristics as miniaturization, high efficiency, low noise, low power consumption, fewer complications, wireless energy transmission and easy implantation, which will surely make it one of the major treatments for heart failure. This article will have a comprehensive review on the development of VAD, its clinical application, current problems and future development direction of VAD.
Ventricular assist device can provide the heart with a nonload circumstance and improve hemodynamics and energy metabolism of ischemic myocardium.With ventricular assistance,not only multiple organ failure is improved but also cardiac function and myocardial injury are resumed. In recent years, studies found that ventricular assistance have an impact on the myocardial interstitium on its structural protein-typeⅠ,Ⅲcollagens and their metabolism conditioning systems.It reverse adverse myocardial remodeling and improve cardiac function by changing myocardial collagen content and distribution.
Heart failure is a leading cause of death in human populations. Because of the insufficient numbers of donor hearts, ventricular assist as a way for the treatment of heart failure and its clinical use is increasing. Initially ventricular assist devices were approved as a bridge-to-recovery indication, and these systems are now increasingly being used as a bridge-to-transplant (BTT) , destination therapy (DT) or permanent support. According to the different structure and working mechanism, ventricular assist device is generally divided into three generation. This review makes a summary on the type of blood pump and its research progress in clinical application.
The implantation of biventricular assist device (BiVAD) is more challenging than that of left ventricular assist device for the interaction in the process of multiple input and output. Besides, ventricular assist device (VAD) often runs in constant speed (CS) mode in clinical use and thus BiVAD also faces the problems of low pulsation and imbalance of blood volume between systemic circulation and pulmonary circulation. In this paper, a delay assist mode for a VAD by shortening the support time of VAD was put forward. Then, the effect of the delay mode on cardiac output, pulsation and the function of the aortic valve was observed by numerical method and the rules of hemodynamics were revealed. The research showed that compared with VAD supported in CS mode, the VAD using delay mode in systolic and diastolic period proposed in this paper could meet the demand of cardiac output perfusion and restore the function of the arterial valves. The open ratio of aortic valve (AV) and pulmonary valve (PV) increased with the time set in delay mode, and the blood through the AV/PV helped to balance the left and the right cardiac volume. Besides, delay mode also improved the pulsation index of arterial blood flow, which is conducive to the recovery of the ventricular pulse function of patients.