Pulsatile Pump Research Articles

Fluid-dynamic effect of pannus formation around the prosthetic heart valve: in vitro demonstration using a heart-mimic pulsatile pump and particle image velocimetry

The abnormal growth of tissue, called pannus, is frequently found in patients who have an implanted prosthetic heart valve. Its growth is related to the valve dysfunction and disturbed blood flow in the aorta. We performed in vitro experiments to demonstrate the effects of pannus formation on hemodynamics and valvular function. The results showed that the opening angle of the heart valve changes depending on the size and shape of the pannus. The circular pannus decreased the maximum opening angle of the heart valve. Although the opening motion of the valve was not affected by the semi-circular pannus, one of the valve leaflets obstructed by the semi-circular pannus had a closing dysfunction during the cardiac cycle, implying aortic insufficiency and regurgitation in the patients with this type of pannus formation. The experimentally measured pressure gradient and velocity-based transvalvular pressure gradient estimation increased with the growth of the pannus, although a discrepancy between the two estimations was observed.

Reversal of renal tissue hypoxia during experimental cardiopulmonary bypass in sheep by increased pump flow and arterial pressure.

Renal tissue hypoxia during cardiopulmonary bypass could contribute to the pathophysiology of acute kidney injury. We tested whether renal tissue hypoxia can be alleviated during cardiopulmonary bypass by the combined increase in target pump flow and mean arterial pressure. Cardiopulmonary bypass was established in eight instrumented sheep under isoflurane anaesthesia, at a target continuous pump flow of 80mL·kg-1min-1 and mean arterial pressure of 65mmHg. We then tested the effects of simultaneously increasing target pump flow to 104mL·kg-1min-1 and mean arterial pressure to 80mmHg with metaraminol (total dose 0.25-3.75mg). We also tested the effects of transitioning from continuous flow to partially pulsatile flow (pulse pressure ~15mmHg). Compared with conscious sheep, at the lower target pump flow and mean arterial pressure, cardiopulmonary bypass was accompanied by reduced renal blood flow (6.8±1.2 to 1.95±0.76mL·min-1kg-1) and renal oxygen delivery (0.91±0.18 to 0.24±0.11mL·O2 min-1kg-1). There were profound reductions in cortical oxygen tension (PO2) (33±13 to 6±6mmHg) and medullary PO2 (31±12 to 8±8mmHg). Increasing target pump flow and mean arterial pressure increased renal blood flow (to 2.6±1.0mL·min-1kg-1) and renal oxygen delivery (to 0.32±0.13mL·O2 min-1kg-1) and returned cortical PO2 to 58±60mmHg and medullary PO2 to 28±16mmHg; levels similar to those of conscious sheep. Partially pulsatile pump flow had no significant effects on renal perfusion or oxygenation. Renal hypoxia during experimental CPB can be corrected by increasing target pump flow and mean arterial pressure within a clinically feasible range.

Sleep Quality after Coronary Artery Bypass Graft Surgery: Comparing Pulsatile and Nonpulsatile Pump Flow

Poor postoperative sleep quality is a common problem in patients undergoing coronary artery bypass graft surgery (CABG). The purpose of this study was to compare the effect of pulsatile and nonpulsatile pump flow on sleep quality of these patients. In this clinical trial, 52 patients undergoing on pump CABG surgery with the roller pump were randomly divided into two equal groups of 26 patients: group 1 using pulsatile pump flow and group 2 nonpulsatile pump flow while the heart was arrested. Sleep score of both groups was evaluated by Pittsburgh Sleep Quality Index questionnaire 2 days before operation and 1 month after operation, and they were compared with each other. Analysis was performed with SPSS software version 22 (SPSS for Windows Inc., Chicago, IL) using the independentt-test, chi-square test, and Fisher exact test. Both groups were the same in demographic characteristics and risk factors such as age, gender, diabetes mellitus, hypertension, hyperlipidemia, smoking, body mass index, and preoperative ejection fraction. Operation data showed no difference between two groups considering cardiopulmonary bypass time and cardiac arrest time. Preoperative sleep quality score of both groups had no significant difference (p= .84). One month postoperative sleep quality score of the pulsatile group was significantly better than that of the nonpulsatile group (p= .04). Using pulsatile flow cardiopulmonary bypass can effectively decrease postoperative sleep disorders in comparison to nonpulsatile flow.

Sleep Quality after Coronary Artery Bypass Graft Surgery: Comparing Pulsatile and Nonpulsatile Pump Flow.

Poor postoperative sleep quality is a common problem in patients undergoing coronary artery bypass graft surgery (CABG). The purpose of this study was to compare the effect of pulsatile and nonpulsatile pump flow on sleep quality of these patients. In this clinical trial, 52 patients undergoing on pump CABG surgery with the roller pump were randomly divided into two equal groups of 26 patients: group 1 using pulsatile pump flow and group 2 nonpulsatile pump flow while the heart was arrested. Sleep score of both groups was evaluated by Pittsburgh Sleep Quality Index questionnaire 2 days before operation and 1 month after operation, and they were compared with each other. Analysis was performed with SPSS software version 22 (SPSS for Windows Inc., Chicago, IL) using the independent t-test, chi-square test, and Fisher exact test. Both groups were the same in demographic characteristics and risk factors such as age, gender, diabetes mellitus, hypertension, hyperlipidemia, smoking, body mass index, and preoperative ejection fraction. Operation data showed no difference between two groups considering cardiopulmonary bypass time and cardiac arrest time. Preoperative sleep quality score of both groups had no significant difference (p = .84). One month postoperative sleep quality score of the pulsatile group was significantly better than that of the nonpulsatile group (p = .04). Using pulsatile flow cardiopulmonary bypass can effectively decrease postoperative sleep disorders in comparison to nonpulsatile flow.

Tomographic PIV analysis of physiological flow conditions in a patient-specific arteriovenous fistula

The arteriovenous fistula (AVF), which is a vasculature created for end-stage renal disease patients who require haemodialysis, is susceptible to many vascular diseases. It is well known that disturbed hemodynamics is a factor in the initiation of vascular disease; however, only a limited number of experimental studies have been conducted to assess the flow behaviour within the AVF. The current study is an investigation of the complex three-dimensional flow within a physiological AVF geometry, using tomographic particle image velocimetry. To this end, a benchtop model of a patient-specific geometry was created by casting silicone around a soluble 3D print of the vessels. The patient-specific boundary conditions were reproduced by driving a refractive-index matched working fluid from a pulsatile pump, which was connected to the model via a tubing network inclusive of valves and compliance chambers. The seeded working fluid was illuminated with a 1 kHz double-pulsed laser, and four high-speed cameras placed at optimised locations were used to capture the particle images, with the volume reconstructions refined by a 3D internal mask created using morphological operations. The velocity magnitude contour plots of the resulting vector field revealed two zones of low velocity in the anastomosis, while locations of high turbulent kinetic energy are observed in the anastomosis and venous regions. These results suggested that the collision of the two opposing inlet flows and the curvature at the anastomosis cause disturbance in the flow that is carried downstream.

Fourth Annual Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs) Report

The Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs), originally a National Institutes of Health-sponsored U.S. database, provides a platform to understand the population of children supported with ventricular assist devices (VADs) during this time of increasing numbers, new devices, expanding indications, and improved outcomes. Between September 19, 2012, and December 31, 2019, 44 hospitals implanted 1031 devices in 856 patients under 19 years of age. Overall, diagnosis was cardiomyopathy in 497 (58%) patients, congenital heart disease (CHD) in 216 (25%), myocarditis in 85 (10%), and other in 58 (7%). Positive outcome (alive on device or bridge to transplantation and recovery) occurred in 82% at 6 months. The patient cohort for implantable continuous (IC) pumps (n= 365) (age 13.2 ± 3.9 years, 18% Interagency Registry for Mechanically Assisted Circulatory Support [Intermacs] profile 1, 23% intubated at implantation, 16% with CHD) was significantly different from the paracorporeal continuous (PC) pump cohort (n= 212) (age 3.6 ± 4.9 years, 46% Intermacs profile 1, 81% intubated, 42% CHD) and the paracorporeal pulsatile (PP) pump cohort (n= 230) (age 2.7 ± 3.5 years, 31% Intermacs profile 1, 76% intubated, 26% CHD). Consistent with their cohort composition, positive outcomes at 6 months based on device type were the following: IC, 92%; PC, 68%; and PP,81%. The incidence of cerebrovascular accidents in the IC, PC, and PP cohorts was 7%, 14%, and 15%, respectively. IC VADs, the most common VAD type placed in children, are associated with improved outcomes compared with PP and PC devices, though PP and PC devices are limited to supporting our most challenging patients. Noteworthy, the incidence of cerebrovascular accidents for pediatric VADs has significantly decreased and is now 11% overall. This report demonstrates again that although often attributed to age, size, or device type, much of the burden in mortality and adverse events is correlated to the patient's overall state at VAD implantation.

Design and Physical Properties of 3-Dimensional Printed Models Used for Neurointervention: A Systematic Review of the Literature.

Three-dimensional (3D) printing has revolutionized training, education, and device testing. Understanding the design and physical properties of 3D-printed models is important. To systematically review the design, physical properties, accuracy, and experimental outcomes of 3D-printed vascular models used in neurointervention. We conducted a systematic review of the literature between January 1, 2000 and September 30, 2018. Public/Publisher MEDLINE (PubMed), Web of Science, Compendex, Cochrane, and Inspec databases were searched using Medical Subject Heading terms for design and physical attributes of 3D-printed models for neurointervention. Information on design and physical properties like compliance, lubricity, flow system, accuracy, and outcome measures were collected. A total of 23 articles were included. Nine studies described 3D-printed models for stroke intervention. Tango Plus (Stratasys) was the most common material used to develop these models. Four studies described a population-representative geometry model. All other studies reported patient-specific vascular geometry. Eight studies reported complete reconstruction of the circle of Willis, anterior, and posterior circulation. Four studies reported a model with extracranial vasculature. One prototype study reported compliance and lubricity. Reported circulation systems included manual flushing, programmable pistons, peristaltic, and pulsatile pumps. Outcomes included thrombolysis in cerebral infarction, post-thrombectomy flow restoration, surgical performance, and qualitative feedback. Variations exist in the material, design, and extent of reconstruction of vasculature of 3D-printed models. There is a need for objective characterization of 3D-printed vascular models. We propose the development of population representative 3D-printed models for skill improvement or device testing.

Design, Implementation, and Validation of a Pulsatile Heart Phantom Pump

The developments in Computed Tomography (CT) and Magnetic Resonance allow visualization of blood flow in vivo using these techniques. However, validation tests are needed to determine a gold standard. For the validation tests, controllable systems that can generate pulsatile flow are needed. In this study, we aimed to develop an affordable pulsatile pump and an artificial circulatory system to simulate the blood flow for validation purposes. Initially, the prerequisites for the phantom were pulsating flow output equal to that of the human cardiac pulse pattern; the flow pattern of the mimicked cardiac output should be equal to that of a human, a variable stroke volume (40–120 ml/beat), and a variable heart rate (60–170 bpm). The developed phantom setup was tested with CT scanner. A washout profile was created based on the image intensity of the selected slice. The test was successful for a heart rate of 70 bpm and a stroke volume of 68 ml, but the system failed to work at various heartbeats and stroke volumes. This was due to the problems with software of the microcontroller. As conclusion in this study, we present a proof of concept for a pulsatile heart phantom pump that can be used in validation tests.

Novel Polydimethylsiloxane (PDMS) Pulsatile Vascular Tissue Phantoms for the In-Vitro Investigation of Light Tissue Interaction in Photoplethysmography.

Currently there exists little knowledge or work in phantoms for the in-vitro evaluation of photoplethysmography (PPG), and its’ relationship with vascular mechanics. Such phantoms are needed to provide robust, basic scientific knowledge, which will underpin the current efforts in developing new PPG technologies for measuring or estimating blood pressure, blood flow and arterial stiffness, to name but a few. This work describes the design, fabrication and evaluation of finger tissue-simulating pulsatile phantoms with integrated custom vessels. A novel technique has been developed to produce custom polydimethylsiloxane (PDMS) vessels by a continuous dip-coating process. This process can accommodate the production of different sized vessel diameters (1400–2500 µm) and wall thicknesses (56–80 µm). These vessels were embedded into a mould with a solution of PDMS and India ink surrounding them. A pulsatile pump experimental rig was set up to test the phantoms, where flow rate (1–12 L·min−1), heart rate (40–120 bpm), and total resistance (0–100% resistance clamps) could be controlled on demand. The resulting flow profiles approximates human blood flow, and the detected contact PPG signal (red and infrared) from the phantom closely resembles the morphology of in-vivo PPG waveforms with signal-to-noise ratios of 38.16 and 40.59 dB, for the red and infrared wavelengths, respectively. The progress made by this phantom development will help in obtaining new knowledge in the behaviour of PPG’s under differing flow conditions, optical tissue properties and differing vessel stiffness.

Shear stress evaluation on blood cells using computational fluid dynamics.

Thrombus formation and hemolysis are important factors in developing blood pumps and mechanical heart valve prostheses. These phenomena are induced by flow properties. High shear stress induces platelet and red cell damage. Computational fluid dynamics (CFD) analysis calculates shear stress of fluid and particle pathlines of blood cells. We studied blood cell damage in a blood pump by using CFD analysis and proposed a method for estimating blood damage. We analyzed a pulsatile blood pump that was developed as a totally implantable left ventricular assist system at Tokai University. Shear stress on blood cells throughout pulsatile blood pumps were analyzed using CFD software. Based on the assumption that the effect of shear stress on platelets is accumulated along the trace, we proposed a method for estimating blood damage using the damage parameter D. Platelet damage parameter is calculated regardless of the division time 𝛥t which is dependent on the calculation time step. The results of the simulations are in good agreement with Giersiepen's equation obtained from the experiments. The history of shear stress on a particle was calculated using CFD analysis. The new damage parameter D yields a value close to that of Giersiepen's equation with small errors.

Fabricating Novel PDMS Vessels for Phantoms in Photoplethysmography Investigations.

This paper introduces a novel technique for the development of custom polydimethylsiloxane (PDMS) vessels for use in phantom technologies. The method involves continuous dip coating of commercial silicone tubes with rapid curation in a single controlled process. The technique accommodates the production of different vessel diameters, wall thicknesses (56 µm-80 µm) and mechanical properties. Clear phantoms were fabricated to compare the commercial silicone tubes against the customs vessels. A pulsatile fluidic pump (BDCLabs, CO, USA) driven by a computer controlled linear motor generated the pulsatile flow through the phantom. The resulting flow profile, using the custom vessels, simulates human blood flow and the detected contact PPG signal from the phantom closely resembles the morphology of in vivo PPG waveforms with signal-to-noise ratios of 38.16 dB and 40.59 dB, compared to the closest commercially-available tubing at 5.38 dB and 10.59 dB for the red and infrared wavelengths respectively. The rigidity and thick walls of commercial silicone tubes impede the expansion of the tubing under systolic pressure. This technique eliminates this common limitation in phantom development.

The effect of pulsatile pump perfusion on hepatitis C transmission in kidney transplantation: A prospective pilot study.

With increasing utilization of hepatitis C (HCV) viremic donor organs, there may be a role for kidney pump perfusion to reduce viral load and prevent HCV transmission. We performed a prospective pilot study of HCV viremic donors; one kidney from each donor pair was pumped with perfusate exchanges and viral load testing at least every 4hours. Donor, recipient, and transplant characteristics were obtained with clinical outcomes. Linear regression was performed to quantify the association between pump time and perfusate viral load. Six HCV viremic donors for six pairs of aviremic recipients were included. Perfusate of the pumped kidneys showed detectable virus throughout the pump cycles. Although perfusate viral levels decreased with increasing pump times, this was not statistically significant (β=-.48, P=.36). All recipients had detectable HCV RNA postoperatively. The pumped cohort had an insignificantly reduced mean viral load compared to pumped recipients (1352±2006 vs 26170±61211, P=.09). Time to initiation of direct-acting antiviral was 32±12 vs 26±7days (P=.17) and to undetectable levels was 66±27 vs 55±22days (P=.82) for the pumped and unpumped cohorts, respectively. Pulsatile perfusion alone does not appear adequate to decrease HCV transmission. Future studies will need to explore additional ex vivo interventions to pumping.

Patient-specific 3D-printed coronary models based on coronary computed tomography angiography volumes to investigate flow conditions in coronary artery disease

Background: 3D printed patient-specific coronary models have the ability to enable repeatable benchtop experiments under controlled blood flow conditions. This approach can be applied to CT-derived patient geometries to emulate coronary flow and related parameters such as Fractional Flow Reserve (FFR). Methods: This study uses 3D printing to compare such benchtop FFR results with a non-invasive CT-FFR research software algorithm and catheter based invasive FFR (I-FFR) measurements. Fifty-two patients with a clinical indication for I-FFR underwent a research Coronary CT Angiography (CCTA) prior to catheterization. CT images were used to measure CT-FFR and to generate patient-specific 3D printed models of the aortic root and three main coronary arteries. Each patient-specific model was connected to a programmable pulsatile pump and benchtop FFR (B-FFR) was derived from pressures measured proximal and distal to coronary stenosis using pressure transducers. B-FFR was measured for two coronary outflow rates (‘normal’, 250 ml min−1; and ‘hyperemic’, 500 ml min−1) by adjusting the model’s distal coronary resistance. Results: Pearson correlations and ROC AUC were calculated using invasive I-FFR as reference. The Pearson correlation factor of CT-FFR and B-FFR-500 was 0.75 and 0.71, respectively. Areas under the ROCs for CT-FFR and B-FFR-500 were 0.80 (95%CI: 0.70–0.87) and 0.81 (95%CI: 0.64–0.91) respectively. Conclusion: Benchtop flow simulations with 3D printed models provide the capability to measure pressure changes at any location in the model, for ultimately emulating the FFR at several simulated physiological blood flow conditions. Clinical Trial Registration: https://clinicaltrials.gov/show/NCT03149042

In Full Flow: Left Ventricular Assist Device Infections in the Modern Era.

With the rising prevalence of heart disease in the United States, there is increasing reliance on durable mechanical circulatory support (MCS) to treat patients with end-stage heart failure. Left ventricular assist devices (LVADs), the most common form of durable MCS, are implanted mechanical pumps that connect to an external power source through a transcutaneous driveline. First-generation LVADs were bulky, pulsatile pumps that were frequently complicated by infection. Second-generation LVADs have an improved design, though infection remains a common and serious complication due to the inherent nature of implanted MCS. Infections can affect any component of the LVAD, with driveline infections being the most common. LVAD infections carry significant morbidity and mortality for LVAD patients. Therefore, it is paramount for the multidisciplinary team of clinicians caring for these patients to be familiar with this complication. We review the epidemiology, prevention, diagnosis, treatment, and outcomes of LVAD infections.

A Valveless Pulsatile Pump for Heart Failure with Preserved Ejection Fraction: Hemo- and Fluid Dynamic Feasibility

Treatment of heart failure with preserved ejection fraction (HFpEF) remains a major unmet medical need. An implantable valveless pulsatile pump with a single cannula—the CoPulse pump—may provide beneficial hemodynamic support for select HFpEF patients when connected to the failing ventricle. We aimed to demonstrate hemodynamic efficacy and hemocompatible design feasibility for this novel assist device. The hemodynamic effect of the pump was investigated with an in vitro circulatory mock loop and an ex vivo isolated porcine heart model. The hydraulic design was optimized using computational fluid dynamics (CFD), and validated by 4D-flow magnetic resonance imaging (MRI). The pump reduced left atrial pressure (> 27%) and increased cardiac output (> 14%) in vitro. Ex vivo experiments revealed elevated total stroke volume at increased end-systolic volume during pump support. Asymmetric cannula positioning indicated superior washout, decreased stagnation (8.06 mm2 vs. 31.42 mm2), and marginal blood trauma potential with moderate shear stresses (< 24 Pa) in silico. Good agreement in flow velocities was evident among CFD and 4D-flow MRI data (r > 0.76). The CoPulse pump proved hemodynamically effective. Hemocompatibility metrics were comparable to those of a previously reported, typical pulsatile pump with two cannulae. The encouraging in vitro, ex vivo, and hemocompatibility results substantiate further development of the CoPulse pump.

Biologically Inspired, Open, Helicoid Impeller Design for Mechanical Circulatory Assist.

Rotating impeller actuated by electromagnet has been a key technological innovation which surpassed earlier limitations of pulsatile pumps. Current impeller design, however, is alien to the functional unit of the human circulatory system and remains a potential cause of adverse prothrombotic events such as hemolysis or pump thrombosis by forcing blood cells to pass over a narrow space available within the rapidly alternating blades attached along its central hub, creating fundamentally a nonphysiologic flow, especially for miniaturized percutaneous blood pumps. Here, we present a biologically inspired, open, helicoid (BiO-H) impeller design for a circulatory assist device that has a fundamentally different footprint from the conventional Archimedean screw-based impeller designs by implementing new design features inspired by an avian right atrioventricular valve. Design parameters including an inner diameter, helix height, overall height, helix revolutions/pitch, blade length, blade thickness, introductory blade angle, number of blades, and blade shape were optimized for maximum output volumetric flow rate through the parametric analysis in computational fluid dynamics simulation. BiO-H shows an improved flow path with 2.25-fold less cross-sectional area loss than the conventional impeller designs. BiO-H with a diameter of 15 mm resulted in a maximum flow rate of 25 L/min at 15,000 revolutions per minute in simulation and showed further improved pressure-flow relationship in benchtop experiments. The design shows promise in increasing flow and could serve as a new impeller design for future blood pumps.

Pulsatile flow pump based on an iterative controlled piston pump actuator as an in-vitro cardiovascular flow model

In-vitro cardiovascular experiments provide an effective means for characterizing structural or hemodynamic features of medical devices before they are tested on animals or used in clinical practice. In-vitro experiments simulate complicated cardiovascular systems with blood pumps, vessels and valves, but without human or animal subjects. Therefore, such experiments are free from ethical issues and present large cost savings in comparison to in-vivo experiments. In this study, we aimed to design a fully programmable pulsatile flow pump that can consistently and accurately reproduce a wide range of physiological flow waveforms without costly transient flowmeter in the system. An iterative control algorithm (ICA) was used to minimize the differences between the desired and produced flow waveforms. Our results confirm that the developed pulsatile pump can replicate flow waveforms accurately, with root mean square errors (RMSEs) of 0.64 L/min and 0.52 mL for the flow rate and stroke volume, respectively.

A physiological control system for ECG-synchronized pulsatile pediatric ventricular assist devices

Ventricular assist devices (VADs) are mechanical pumps used to provide support to the circulatory system of patients with ventricular dysfunction that are waiting for heart transplantation. The majority of pulsatile VADs are used in the fill-to-empty mode or the asynchronous mode at a fixed rate. However, when this support lasts for weeks or months, physiological control systems can improve the treatment by changing VAD operation in response to changes in the cardiovascular system. In this work, a physiological control system was developed to adjust the pump ejection pressure at each cardiac cycle to keep the mean arterial pressure at a specified reference value. A polynomial controller was used, and the optimum parameters for this controller were determined by using the interior-point method to solve a constrained minimization problem. A heartbeat detection algorithm based on electrocardiogram signals (ECG) is used in such a way the control system works in synchronization with the physiological heartbeat. Mathematical models of the pediatric cardiovascular system (pCVS) and a pulsatile pediatric pump were used to evaluate the cardiovascular response under ventricular assistance. Computational simulation results were analyzed, and based on them one may conclude that the synchronous physiological control system adapted the cardiovascular response to the changes in references values, defined in accordance with the patient clinical status.

Biocompatible materials of pulsatile and rotary blood pumps: A brief review

AbstractThe biomedical materials that have been used in the structure of heart pumps are classified as biocompatible, and these can be metals, polymers, ceramics, and composites. Their positions in the pump vary according to the part’s function. Whereas various materials have different properties, all biomaterials chosen for cardiovascular applications should have excellent blood biocompatibility to reduce the likelihood of hemolysis and thrombosis. There are two major categories of the heart pumps; pulsatile and rotary blood pumps (axial and centrifugal) and the features of some of these materials allow them to be used in both. Rotary and pulsatile blood pump devices have to be fabricated from materials that do not result in adverse biological responses. The purpose of this review is to study the available biocompatible materials for the pulsatile and rotary blood pumps as clinically-approved materials and prototype heart pump materials. The current state of bio-compatible materials of rotary and pulsatile blood pump construction is presented. Some recent applications of surface amendment technology on the materials for heart assist devices were also reviewed for better understanding. The limitations of heart assist devices, and the future direction of artificial heart elements have been considered. This review will be considered as a comprehensive reference to rapidly understanding the necessary research in the field of biocompatible materials of pulsatile and blood rotary pumps.

Intrinsic Investigations of Physiological Interaction for Pulsatile Rotary Blood Pumps

Background and Aim: One of the major concerns with the use of circulatory assist devices (CADs) is their performance during the transition from supine to standing position. In standing position, vasodilatation of veins occurs in the legs, which decreases left ventricular end-diastolic pressure, and, in turn, the preload to the CAD. This research numerically studies the physiological interaction of pulse left ventricular assist devices (LVADs) in relation to cardiac output and stroke volume under systolic and diastolic situations. Methods: A cardiovascular system (CVS) model was used to configure the output of heart failure (HF) status by changing system parameters in one cardiac cycle, whereas LVAD pump was configured to change the fixed rotational speed. The terms of the pump cannulae model, real-time detection of aortic valve status, left ventricular stroke volume analysis, and LVAD control method were designed and analyzed. Results: The results showed that end-diastolic left and right ventricular volumes – pressures in heart failure condition were reduced from 183 mL to 164 mL with continuous fixed speed RBP support, Alongside with a corresponding increase in ejection fraction (16%). Conclusions: The results show that LVADs are more sensitive to preload than afterload when operating at a fixed speed.