Regurgitation is an abnormal condition happens when left ventricular assist devices (LVADs) operated at a low speed, which causes LVAD to fail to assist natural blood-pumping by heart and thus affects patients’ health. According to the degree of regurgitation, three LVAD’s regurgitation states were identified in this paper: no regurgitation, slight regurgitation and severe regurgitation. Regurgitation index (RI), which is presented based on the theory of dynamic closed cavity, is used to grade the regurgitation of LVAD. Numerical results showed that when patients are in exercising, resting and sleeping state, the critical speed between slight regurgitation and no regurgitation are 6 650 r/min, 7 000 r/min and 7 250 r/min, respectively, with corresponding RI of 0.401, 0.300 and 0.238, respectively. And the critical speed between slight regurgitation and severe regurgitation are 5 500 r/min, 6 000 r/min and 6 450 r/min, with corresponding RI of 0.488, 0.359 and 0.284 respectively. In addition, there is a negative relation correction between RI and rotational speed, so that grading the LVAD’s regurgitation can be achieved by determining the corresponding critical speed. Therefore, the detective parameter RI based on the signal of flow is proved to be able to grade LVAD’s regurgitation states effectively and contribute to the detection of LVAD’s regurgitation, which provides theoretical basis and technology support for developing a LVADs controlling system with high reliability.
Objective To investigate the feasibility of a long-term left ventricular assist device placed in the aortic valve annulus for terminal cardiopathy. Methods An implantable aortic valve pump （23ram outer diameter, weighing 31g） was developed. There were a central rotor and a stator in the device. The rotor was consisted of driven magnets and an impeller, the stator was consisted of a motor coil with an iron core and outflow guide vanes. The device was implanted identical to an aortic valve replacement, occupying no additional anatomic space. The blood was delivered directly from left ventricle to the aortic root by aortic valve pump like natural ventricle, neither connecting conduits nor ＂bypass＂ circuits were necessary, therefore physiologic disturbances of natural circulation was less. Results Aortic valve pump was designed to cycle between a peak flow and zero net flow to approximate systole and diastole. Bench testing indicated that a blood flow of 7L/min with 50 mmHg（1kPa = 7.5mmHg） pressure could be produced by aortic valve pump at 15 000r/min. A diastole aortic pressure of 80mmHg could be maintained by aortic valve pump at 0L/min and the same rotating speed. Conclusions This paper exhibits the possibility that an aortic valve pump with sufficient hemodynamic capacity could be made in 23mm outer diameter, 31g and it could be implantable. This achievement is a great progress to extend the applications of aortic valve pump in clinic and finally in replacing the natural donor heart for heart transplantation. Meanwhile, this is only a little step, because many important problems, such as blood compatibility and durability, require further investigation.
The implantation of left ventricular assist device (LVAD) has significantly improved the quality of life for patients with end-stage heart failure. However, it is associated with the risk of complications, with unplanned readmissions gaining increasing attention. This article reviews the influencing factors, prediction methods and models, and intervention measures for unplanned readmissions in LVAD patients, aiming to provide scientific guidance for clinical practice, assist healthcare professionals in accurately assessing patients' conditions, and develop rational care plans.
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.
ObjectiveTo compare the perioperative renal function changes in patients undergoing heart transplantation (HT) and left ventricular assist device (LVAD) implantation. MethodsPatients with end-stage heart failure who underwent surgical treatment at Beijing Anzhen Hospital, Capital Medical University from January 2019 to April 2024 were included. According to the surgical method, patients were divided into a HT group and a LVAD group, and the estimated glomerular filtration rate (eGFR) of patients before surgery and postoperative 1, 7, 30, 60 days was compared between the two groups. The patients with preoperative renal dysfunction were subdivided into subgroups for comparison of eGFR changes before surgery and 30 days after surgery between the two groups. ResultsA total of 112 patients were enrolled. There were 78 patients in the HT group, including 61 males and 17 females, aged (44.42±18.51) years. There were 34 patients in the LVAD group, including 30 males and 4 females, aged (54.94±11.37) years. Compared with the HT group, the average age of patients in the LVAD group was greater (P<0.001), body mass index was higher (P=0.008), preoperative eGFR was lower (P=0.009), and the proportions of smokers (P=0.017), alcohol drinkers (P=0.041), and diabetes mellitus (P=0.028) patients were higher. Among patients with preoperative renal dysfunction [eGFR<90 mL/(min·1.73 m2)], compared with the HT group, the postoperative eGFR of the LVAD group was significantly higher than that of the HT group, and it was significantly increased compared with that before surgery; the postoperative eGFR of the HT group was comparable to that before surgery, and more than half of the patients had a lower eGFR than before surgery. Among patients with preoperative renal dysfunction, 11 patients in the HT group received continuous renal replacement therapy, and 8 died early; 2 patients in the LVAD group received continuous renal replacement therapy, and 1 died early. ConclusionFor end-stage heart failure patients with combined renal dysfunction, compared with HT, LVAD implantation enables patients to obtain better renal function benefits.
Although heart transplantation remains to be the optimal treatment for advanced heart failure, its use has been largely limited due to shortage of available donor organs. Over the past two decades, left ventricular assist device (LVAD) has been significantly modified in size, durability and hemocompatibility. In addition to the bridge to transplantation, LVAD has become an attractive alternative to heart transplantation for end-stage heart failure as destination therapy for unsuitable candidates. Although the performance of LVAD has been improving greatly in recent years, there are still great challenges in the management of device complications and low quality of life after implantation. This review will summarize the types of LVAD, indications for implantation, postoperative management and adverse events.
Heart failure is one kind of cardiovascular disease with high risk and high incidence. As an effective treatment of heart failure, artificial heart is gradually used in clinical treatment. Blood compatibility is an important parameter or index of artificial heart, and how to evaluate it through hemodynamic design and in vitro hemolysis test is a research hotspot in the industry. This paper first reviews the research progress in hemodynamic optimization and in vitro hemolysis evaluation of artificial heart, and then introduces the research achievements and progress of the team in related fields. The hemodynamic performance of the blood pump optimized in this paper can meet the needs of use. The normalized index of hemolysis obtained by in standard vitro hemolysis test is less than 0.1 g/100 L, which has good hemolysis performance in vitro. The optimization method described in this paper is suitable for most of the development of blood pump and can provide reference for related research work.
Implantable left ventricular assist device (LVAD) has become an essential treatment for end-stage heart failure, and its effect has been continuously improved. In the world, magnetic levitation LVAD has become mainstream and is increasingly used as a destination treatment. China has also entered the era of ventricular assist device. The continuous improvement of the ventricular assist device will further improve the treatment effect. This article reviews the current situation and development trend of LVAD treatment in China and abroad.