Mechanical circulatory support is necessary when heart failure becomes refractory to medical support. It is typically instituted when organ dysfunction occurs as a result of hypoperfusion. Enthusiasm has recently developed for the role of mechanical circulatory support in the ever-growing population of heart failure patients. Indeed, efforts in developing this technology have allowed for the relatively recent development of a variety of complete circulatory support devices. The use of left ventricular assist devices (LVADs) in patients with advanced heart failure results in a clinically meaningful survival benefit and an improved quality of life, and LVADs could be an acceptable alternative therapy for selected patients who are not candidates for cardiac transplantation.
Assisted Circulation ; Heart ; Heart Failure ; Heart Transplantation ; Heart-Assist Devices ; Humans ; Life Support Systems ; Quality of Life

The impeller profile, which is one of the most important factors, determines the creation of shear stress which leads to blood hemolysis in the internal flow of centrifugal blood pump. The investigation of the internal flow field in centrifugal blood pump and the estimation of the hemolysis within different impeller profiles will provide information to improve the performance of centrifugal blood pump. The SST kappa-omega with low Reynolds correction was used in our laboratory to study the internal flow fields for four kinds of impellers of centrifugal blood pump. The flow fields included distributions of pressure field, velocity field and shear stress field. In addition, a fast numerical hemolysis approximation was adopted to calculate the normalized index of hemolysis (NIH). The results indicated that the pressure field distribution in all kinds of blood pump were reasonable, but for the log spiral impeller pump, the vortex and backflow were much lower than those of the other pumps, and the high shear stress zone was just about 0.004%, and the NIH was 0.0089.
Assisted Circulation ; Heart-Assist Devices ; Hemolysis ; Humans ; Models, Theoretical ; Stress, Mechanical

The purpose of this paper is to report the research and design of control system of magnetic coupling centrifugal blood pump in our laboratory, and to briefly describe the structure of the magnetic coupling centrifugal blood pump and principles of the body circulation model. The performance of blood pump is not only related to materials and structure, but also depends on the control algorithm. We studied the algorithm about motor current double-loop control for brushless DC motor. In order to make the algorithm adjust parameter change in different situations, we used the self-tuning fuzzy PI control algorithm and gave the details about how to design fuzzy rules. We mainly used Matlab Simulink to simulate the motor control system to test the performance of algorithm, and briefly introduced how to implement these algorithms in hardware system. Finally, by building the platform and conducting experiments, we proved that self-tuning fuzzy PI control algorithm could greatly improve both dynamic and static performance of blood pump and make the motor speed and the blood pump flow stable and adjustable.
Algorithms ; Assisted Circulation ; instrumentation ; Fuzzy Logic ; Heart-Assist Devices ; Magnetic Phenomena ; Magnetics

Artificial heart is an effective device in solving insufficient native heart supply for heart transplant, and the research and application of novel actuators play an important role in the development of artificial heart. In this paper, artificial muscle is introduced as the actuators of direct cardiac compression assist, and some of its parameters are compared with those of native heart muscle. The open problems are also discussed.
Artificial Organs ; Assisted Circulation ; instrumentation ; Biocompatible Materials ; Equipment Design ; Heart-Assist Devices ; Humans ; Muscles

AIMTo evaluate the therapeutic effects of a left ventricular assist device (LVAD) on pump failure caused by acute myocardial infarction (AMI) in dogs.

METHODSThe pump failure caused by AMI was established in 18 dogs, 9 of them were treated with a LVAD that could expel the autoblood from the left ventricle into the aorta and named the experimental group, and the rest of them were treated with intravenous infusion and served as the control group. The changes of arrhythmia, mortality, pulmonary capillary wedge pressure (PCWP), left ventricular end-diastolic pressure (LVEDP), peripheral artery pressure and the diameter of left ventricular chamber were observed.

RESULTSThe ratio of ventricular extrasystole and the mortality resulted from ventricular fibrillation of the experimental group were lower than that of the control group. The systolic blood pressure of peripheral artery of the control group was significantly lower (< 100 mmHg) than that of the experimental group (>100 mmHg, P < 0.01). The PCWP and LVEDP of the experimental group during all the stages 45 minutes after the procedures were significantly lower than that of the control group (P < 0.01). The left ventricular end-diastolic diameter of the control group was larger than that of the experimental groups (P < 0.01).

CONCLUSIONTo assist circulation by expelling autoblood from left ventricle into aorta in dogs with AMI could reduce the frequency of ventricular fibrillation, improve hemodynamics, and prevent the enlargement of left ventricle. Therefore, it could play an important role in assisting the left ventricular functions.

Animals ; Assisted Circulation ; methods ; Disease Models, Animal ; Dogs ; Heart-Assist Devices ; Hemodynamics ; Myocardial Infarction ; physiopathology ; therapy ; Ventricular Function, Left

Mechanical circulatory support (MCS) has been used for myocardium failure, but moreover, it may be essential for the life support in cardiac arrest or cardiogenic shock. Many commercial devices can be used effectively for the long-term support. However, there are some limitations in the aspects of the cost and technical support by production company. Short-term support with centrifugal type has been reported numerously with the purpose of bridging to heart transplantation or recovery. We successfully treated 5 patitents who were in the status of cardiogenic shock (n=3) or arrest (n=2) with the technique of extracorporeal life support system (ECLS) or left ventricular assist device (LVAD) using the centrifugal type pump. The MCS were performed emergently (n=2) under cardiac arrest caused by ischemic heart disease, and urgently (n=3) under cardiogenic shock with ischemic heart disease (n=1) or acute fulminant viral myocarditis (n=2). All patients were weaned from MCS. Complications related to the use of MCS were bleeding and acute renal failure, but there were no major complications related to femoral cannulations. Mechanical circulatory support may be essential for the life support and rescue in cardiac arrest or cardiogenic shock.
Acute Kidney Injury ; Assisted Circulation ; Cardiopulmonary Bypass ; Catheterization ; Heart Arrest* ; Heart Transplantation ; Heart-Assist Devices ; Hemorrhage ; Humans ; Life Support Systems ; Myocardial Ischemia ; Myocarditis ; Myocardium ; Shock, Cardiogenic*

OBJECTIVETo establish a pig model of chronic external counterpulsation.

METHODSTwelve pigs were anaesthetized with sodium pentobarbital (< or =30 mg/kg.b.w.) and 846 mixture (< or =0.1 ml/kg.b.w.) and counterpulsed in a lateral position for 2 h every two days (totally 36 h) with 0.025 to 0.04 MPa/cm(2) pressure.

RESULTSExternal counterpulsation was successfully completed in all the animals. Combined administration of sodium pentobarbital and 846 mixture resulted in good anesthetic effect with reduced anesthetic dosage and minimal side effect on the viscera (the liver, kidney and heart, etc).

CONCLUSIONThe pig model of chronic external counterpulsation has been successfully established. Combined use of sodium pentobarbital and 846 mixture is recommended for chronic external counterpulsation.

Anesthesia, General ; methods ; Animals ; Animals, Newborn ; Assisted Circulation ; Counterpulsation ; methods ; Models, Animal ; Pentobarbital ; administration & dosage ; Swine

A new-designed axial flow blood pump, dived by magnetic coupling and using internal hollow brushless DC motor and inlet and outlet in line with impeller, was tested in mimic circuit. The results showed good performance of the new pump and indicated that its hydrodynamic characteristic can meet the demands of clinical extracorporeal circulation and auxiliary circulation.
Assisted Circulation ; instrumentation ; Equipment Design ; Extracorporeal Circulation ; instrumentation ; Hydrodynamics ; Magnetics

This study was directed at estimating the value of platelet count in the course of in-vitro hemolytic tests by roller pump. Five paired in-vitro tests were conducted using the POLYSTAN pump(group A) and COBE pump(group B). The pumps ran 16 hours. The samples for platelet count and plasma-free hemoglobin were taken before pumping, and every 2 hours after 4 hours of pumping. The 2 groups' platelet count and plasma-free hemoglobin levels were found to be linearly increasing with the hours of pumping and linear regression analysis showed the platelet count and plasma-free hemoglobin were positively correlated. These data suggested that platelet count could be used as an index in evaluating the in-vitro hemolytic properties of blood pumps.
Assisted Circulation ; Hemoglobins ; analysis ; Hemolysis ; Humans ; Linear Models ; Platelet Count

OBJECTIVETo explore the clinical application of Intra-aortic balloon pump (IABP) and centrifugal pump in low cardiac output syndrome (LCOS) after coronary artery bypass grafting (CABG).

METHODSFrom April 2000 to January 2004, 5 patients suffered serious LCOS after CABG in our department. Because maximum vasoactive agent had no significant effect, we supported these 5 patients with IABP and centrifugal pumps. The centrifugal pumps were connected with cannulas of right superior pulmonary vein and ascending aorta. The flow rate of the centrifugal pumps were increased to 3-4 L/min gradually. The dosage of vasoactive agent and flow rate of the centrifugal pumps were decreased gradually after hemodynamics stabilized.

RESULTSAll 5 patients' hemodynamics were improved significantly after the left ventricular assist by IABP and centrifugal pumps. Five patients were weaned from the centrifugal pumps after 4 to 7 days successfully. But some degree damage to blood cells and renal function were detected. Renal function of 3 patients were recovered gradually after centrifugal pumps removed and discharged successfully, One patient died of acute renal failure, 1 patient died of multiple organ failure, 5 patients need transfusion of whole blood or concentrated erythrocytes and 4 patients need transfusion of platelets.

CONCLUSIONSThere were significant improvements in hemodynamics after support with IABP and centrifugal pumps in the patients who suffered serious LCOS with less effect of maximum vasoactive agent after CABG. Some complications on blood cells and renal function should be paid more attention.

Aged ; Cardiac Output, Low ; etiology ; surgery ; Coronary Artery Bypass ; adverse effects ; Heart-Assist Devices ; Humans ; Intra-Aortic Balloon Pumping ; Male ; Middle Aged ; Retrospective Studies ; Treatment Outcome