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.
We propose a control model of the cardiovascular system coupled with a rotary blood pump in the present paper. A new mathematical model of the rotary heart pump is presented considering the hydraulic characteristics and the similarity principle of pumps. A seven-order nonlinear spatial state equation adopting lumped parameter is used to describe the combined cardiovascular-pump model. Pump speed is used as the control variable. To achieve sufficient perfusion and to avoid suction, a feedback strategy based on minimum (diastolic) pump flow is used in the control model. The results showed that left ventricular assist device (LVAD) could improve hemodynamics of the cardiovascular system of the patient with heart failure in open loop. When rotation speed was 9,000 r/min, cardiac output reached 82 mL/s while the initial cardiac output was only 34 mL/s without the LVAD support. When the rotation speed was above 12 800 r/min, suction was found because the high rotating speed resulted in insufficient venous return volume. Suction was avoided by adopting the feedback control. The model reveals the interaction of LVAD and the cardiovascular system, which provides theoretical basis for the therapy of heart failure in the left ventricular and for the design of a physiological control strategy.
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.
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.
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.
Objective To compare the early outcomes of domestic third-generation magnetically levitated left ventricular assist device (LVAD) with or without concomitant mitral valvuloplasty (MVP). Methods The clinical data of 17 end-stage heart failure patients who underwent LVAD implantation combined with preoperative moderate to severe mitral regurgitation in Fuwai Central China Cardiovascular Hospital from May 2018 to March 2023 were retrospectively analyzed. The patients were divided into a LVAD group and a LVAD+MVP group based on whether MVP was performed simultaneously, and early outcomes were compared between the two groups. Results There were 4 patients in the LVAD group, all males, aged (43.5±5.9) years, and 13 patients in the LVAD+MVP group, including 10 males and 3 females, aged (46.8±16.7) years. All the patients were successful in concomitant MVP without mitral reguragitation occurrence. Compared with the LVAD group, the LVAD+MVP group had a lower pulmonary artery systolic pressure and pulmonary artery mean pressure 72 h after operation, but the difference was not statistically different (P>0.05). Pulmonary artery systolic pressure was significantly lower 1 week after operation, as well as pulmonary artery systolic blood pressure and pulmonary artery mean pressure at 1 month after operation (P<0.01). There was no statistically significant difference in blood loss, operation time, cardiopulmonary bypass time, aortic cross-clamping time, mechanical ventilation time, or ICU stay time between the two groups (P>0.05). The differences in 1-month postoperative mortality, acute kidney injury, reoperation, gastrointestinal bleeding, and thrombosis and other complications between the two groups were not statistically significant (P>0.05). Conclusion Concomitant MVP with implantation of domestic third-generation magnetically levitated LVAD is safe and feasible, and concomitant MVP may improve postoperative hemodynamics without significantly increasing perioperative mortality and complication rates.
Objective To investigate the efficacy and safety of the Corheart 6 left ventricular assist system in patients with end-stage heart failure. Methods A retrospective study was conducted on patients with end-stage heart failure who were treated with Corheart 6 left ventricular assist system from March 2022 to June 2024 in 4 hospitals in Jiangsu Province. The efficacy of the device was evaluated by comparing changes in clinical indicators at preoperative, discharge, 3-month postoperative, and 6-month postoperative timepoints, including the New York Heart Association (NYHA) functional classification, left ventricular ejection fraction (LVEF), and left ventricular end-diastolic diameter (LVEDD). The safety of the device was assessed by analyzing the intraoperative position and orientation of the blood pump inlet cannula, as well as the incidence of adverse events. Results In this study, 39 patients were collected, including 34 males and 5 females with a mean age of (56.4±12.5) years, ranging from 20 to 75 years. There was no operative death. There was no death in postoperative 3 months with a survival rate of 100.0%. There were 3 deaths in 6 months postoperatively, with a survival rate of 92.3%. All patients had a preoperative NYHA cardiac function classification of class Ⅳ. The NYHA cardiac function class of the patients improved (P<0.05) at discharge, 3 and 6 months after surgery when compared to the preoperative period. LVEF was significantly higher at 3 months after surgery than that during the preoperative period (P<0.05). LVEDD was significantly smaller at discharge, 3 and 6 months after surgery than that during the preoperative period (P<0.05). The safety evaluation's findings demonstrated that all 39 patients' intraoperative blood pump inlet tubes were oriented correctly, the artificial blood vessel suture sites were appropriate, there were no instances of device malfunction or pump thrombosis, or instances of bleeding or hemolysis, and the rate of the remaining adverse events was low. Conclusion With a low rate of adverse events and an excellent safety profile, the Corheart 6 left ventricular assist system can efficiently enhance cardiac function in patients with end-stage heart failure. It also has considerable clinical uses.
In China, more than half of heart failure patients are ischemic heart failure patients. And a large proportion of left ventricular assist device implantation patients are also ischemic heart failure patients. However, left ventricular assist device implantation in ischemic heart failure patients is facing with problems such as patient screening, coronary artery disease, small left ventricle, mitral insufficiency, and ventricular aneurysm. There are only a few retrospective studies with small sample sizes abroad trying to provide solutions to these problems. While there is a lack of systematic understanding of this issue in China. Therefore, we provide an overview of the application and progress of left ventricular assist devices in ischemic heart failure patients, aiming to help clinicians have a comprehensive understanding of this issue and provide some guidance.
A 56-year male patient was implanted with a third generation magnetic levitation HeartCon left ventricular assist device (LVAD) for refractory heart failure through a left antero-lateral thoracotomy. Inflow cannula of the HeartCon blood pump was inserted via the left apex and outflow tract with the artificial blood vessel was sutured to the descending aorta. The operation process was smooth, the LVAD worked stably, and results of left ventricular assist was good. Implantation of HeartCon LVAD through the left antero-lateral thoracotomy is an alternative technique with less surgical complications, less trauma and satisfactory results.
As a global disease, heart failure affects at least 26 million people, and its prevalence is still rising. Besides, the mortality rate and readmission rate remain high. Advanced heart failure is the terminal stage of various heart diseases, and often requires some treatments other than drug intervention, such as heart transplantation which is the gold standard for treatment of heart failure. However, limited by the number of donors, the number of heart transplants in the world has reached a bottleneck. There is a huge gap between the number of patients who need heart transplants and patients who get hearts for survival successfully in reality. With the exploration and development of mechanical circulation support devices for more than half a century, they have become a wonderful treatment for patients with advanced heart failure. This article will introduce the latest progress of mechanical circulatory support devices at home and abroad from the aspects of temporary and long-term devices.