Cardiac Assist Devices Research Articles

MRI in Patients with Cardiovascular Implantable Electronic Devices and Fractured or Abandoned Leads.

Purpose To examine the clinical effect of lead length and lead orientation in patients with cardiac implantable electronic devices (CIEDs) and lead fragments or abandoned leads undergoing 1.5-T MRI. Materials and Methods This Health Insurance Portability and Accountability Act-compliant retrospective study included patients with CIEDs and abandoned leads or lead fragments undergoing 1.5-T MRI from March 2014 through July 2020. CIED settings before and after MRI were reviewed, with clinically significant variations defined as a composite of the change in capture threshold of at least 50%, in sensing of at least 40%, or in lead impedance of at least 30% between before MRI and after MRI interrogation. Adverse clinical events were assessed at MRI and up to 30 days after. Univariable and multivariable analysis was performed. Results Eighty patients with 126 abandoned CIED leads or lead fragments underwent 107 1.5-T MRI examinations. Sixty-seven patients (median age, 74 years; IQR, 66-78 years; 44 male patients, 23 female patients) had abandoned leads, and 13 (median age, 66 years; IQR, 52-74 years; nine male patients, four female patients) had lead fragments. There were no reported deaths, clinically significant arrhythmias, or adverse clinical events within 30 days of MRI. Three patients with abandoned leads had a significant change in the composite of capture threshold, sensing, or lead impedance. In a multivariable generalized estimating equation analysis, lead orientation, lead length, MRI type, and MRI duration were not associated with a significant change in the composite outcome. Conclusion Use of 1.5-T MRI in patients with abandoned CIED leads or lead fragments of varying length and orientation was not associated with adverse clinical events. Keywords: Cardiac Assist Devices, MRI, Cardiac Implantable Electronic Device Supplemental material is available for this article. © RSNA, 2024.

Echocardiography in Cardiac Assist Devices.

In patients with medically refractory heart failure or cardiogenic shock, both temporary and durable mechanical circulatory support devices can be used to support cardiac circulation. Both transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) are widely available, relatively noninvasive, and avoid radiation exposure. Thus, echocardiography is an invaluable tool that provides vital information aiding in preprocedure evaluation, placement, management, and weaning of cardiac assist devices. The purpose of this article is to review the utility of both TTE and TEE in managing patients with cardiac assist devices.

Radiology of Intra-Aortic Balloon Pump Catheters.

Radiographs play an important role in ascertaining appropriate placement of the intra-aortic balloon pump catheter. This imaging essay highlights correct and incorrect positioning of these catheters, with emphasis on the variability of radiopaque markers used with different catheter models and on axillary versus femoral catheter placement routes. Keywords: Conventional Radiography, CT, Percutaneous, Cardiac, Vascular, Aorta, Anatomy, Cardiac Assist Devices, Catheters © RSNA, 2022.

Control-Oriented Modeling and Analysis of Tubular Dielectric Elastomer Actuators Dedicated to Cardiac Assist Devices

This letter deals with the control-oriented modeling of a multilayered dielectric elastomer actuator based tube. The actuator is clamped at both sides and performs a radial displacement. The hyperelastic deformation and the viscoelastic performance, together with the electro-mechanical coupling are considered in the model. With the chosen Yeoh’s model for the Helmholtz free energy function, we aim to model the snap-through effect of this tubular actuator at high applied voltage. Simulation results of the nonlinear dynamic model are later compared with experimental ones in order to identify unknown parameters of the dielectric elastomer, especially to fit the snap-through effect and the high frequency performance. With proper identification process, our model has a good accuracy to fit the physical system (more than 90.27% for a ramp input and more than 82.7% for a step input) and is ready for the future controller design.

Transcutaneous Energy Transfer System for Cardiac-Assist Devices by Use of Inhomogeneous Biocompatible Core Material

A novel magnetic liquid silicone rubber composite core design applicable to wireless power transfer (WPT) for medical applications is presented. As a case study, the integration of WPT, including the proposed cores for the coils, with ventricular-assist devices (VADs) was investigated. This facilitates transferring 4.6 W of power wirelessly through the skin layer, which, thus, allows to disposal of the transcutaneous cable that connects the extracorporal batteries to the implanted blood pump. To enhance the coupling coefficient and consequently increase the WPT efficiency, the geometry of the cores was optimized. This reduces the temperature increase in the implant area. The field and thermal simulations were carried out with CST software. The electrical properties of the proposed design as obtained by simulation were validated by measurements. The simulation results perfectly coincide with the measured results. Finally, a new optimized design with additional high permeability core inserts is introduced to further increase the coupling coefficient. The results indicate that the coupling coefficient is increased from 0.31 to 0.52 with the optimized design compared to the case without cores. Moreover, by fixing the initial temperature as 37 °C, the maximum temperature is decreased from 38.19 °C to 37.27 °C while keeping the transferred power fixed. Its high magnetic conductivity, biocompatibility, low-loss property, flexibility, and Qi-standard compatibility make the proposed WPT design an excellent candidate for the wireless powering of heart-assist devices, such as VADs.

Mock circulatory loops used for testing cardiac assist devices: A review of computational and experimental models.

Heart failure is a major health risk, and with limited availability of donor organs, there is an increasing need for developing cardiac assist devices (CADs). Mock circulatory loops (MCL) are an important in-vitro test platform for CAD's performance assessment and optimisation. The MCL is a lumped parameter model constructed out of hydraulic and mechanical components aiming to simulate the native cardiovascular system (CVS) as closely as possible. Further development merged MCLs and numerical circulatory models to improve flexibility and accuracy of the system; commonly known as hybrid MCLs. A total of 128 MCLs were identified in a literature research until 25 September 2020. It was found that the complexity of the MCLs rose over the years, recent MCLs are not only capable of mimicking the healthy and pathological conditions, but also implemented cerebral, renal and coronary circulations and autoregulatory responses. Moreover, the development of anatomical models made flow visualisation studies possible. Mechanical MCLs showed excellent controllability and repeatability, however, often the CVS was overly simplified or lacked autoregulatory responses. In numerical MCLs the CVS is represented with a higher order of lumped parameters compared to mechanical test rigs, however, complex physiological aspects are often simplified. In hybrid MCLs complex physiological aspects are implemented in the hydraulic part of the system, whilst the numerical model represents parts of the CVS that are too difficult to represent by mechanical components per se. This review aims to describe the advances, limitations and future directions of the three types of MCLs.

Trends in the Use of Cardiac Assist Devices in Heart Failure Patients with Cardiogenic Shock

Introduction Currently, the most frequently used mechanical assist device for cardiogenic shock is the intra-aortic balloon pump (IABP). IABPSHOCK II trial in 2012 failed to show any benefits, therefore, the use of an IABP was downgraded to a Class IIA recommendation in the 2013 AHA/ACC guidelines. With recent innovations, the use of percutaneous ventricular assist devices (pVADs) is becoming common. We have looked at the recent trends in the use of pVADS and IABP in patients of heart failure with cardiogenic shock. Methods Data from national inpatient from the year 2002 to 2016 was used for temporal trends. ICD 9 and ICD 10 codes were used to identify patients of heart failure with cardiogenic shock and the use of heart assist devices. Pearson Chi-square was used for categorical variables and the t-test was used for continuous variables. Results We identified 319, 696 patient encounters. Median age was 68 (interquartile range 58-78) years. Mortality was very high at 27.0% (86,360). 30.8% (98,570) patients underwent left heart catheterization. Percutaneous coronary intervention (PCI) was done in 14.4% (45,914) patients. In 4.4%(13,977) external Left ventricular assist device (LVAD), in 3.0% (9525) percutaneous Ventricular assist devices (pVADs), in 20.3% (64,807) intra-aortic balloon pump (IABP) and in 9.3 (29,861) vasopressors were used. There has been an increasing trend in the use of pVADs while a decreasing trend was noticed in the use of IABP. Vasopressin and LVADs have shown a variable trend (Figure). Conclusion Use of IABP has decreased while the use of pVADs has increased over the years in patients with cardiogenic shock.

Improving In vitro Evaluation Capabilities of Cardiac Assist Devices through a Validated Exercise Simulation.

Cardiac assist devices require thorough in vitro evaluation prior to in vivo animal trials, which is often undertaken in mock circulatory loops. To allow for best possible device development, mock circulatory loops need to be able to simulate a variety of patient scenarios. Transition from rest to exercise is one of the most commonly simulated patient scenarios, however, to validate in vitro exercise test beds, baseline data on how the healthy heart and circulatory system responds to exercise is required. Steady state and time response data for heart rate (HR), stroke volume (SV) and cardiac output (CO) was continuously recorded using impedance cardiography in 50 healthy subjects (27 male / 23 female) during exercise on a recumbent exercise ergometer. This data was then used to implement an exercise simulation in a mock circulatory loop and both the steady state and transient results were compared with the mean response of subjects transitioning from rest to 60 W exercise. When transitioning from rest to exercise the time constant (τ) and rise time (tr) for HR, SV and CO were between 10.6-19.3s and 24.7-44.3s respectively for both sexes. No significant differences between the genders were found for τ and tr (p>0.05). Mock circulatory loop results of HR, SV and CO were in good accordance with human data. The present data was used to successfully validate in vitro exercise simulations and may be used to validate in silico numerical simulations of exercise, thus further improving the evaluation capabilities for existing and under development cardiac assist devices.

Cardiac Assist Devices: Early Concepts, Current Technologies, and Future Innovations.

Congestive heart failure (CHF) is a debilitating condition that afflicts tens of millions of people worldwide and is responsible for more deaths each year than all cancers combined. Because donor hearts for transplantation are in short supply, a safe and durable means of mechanical circulatory support could extend the lives and reduce the suffering of millions. But while the profusion of blood pumps available to clinicians in 2019 tend to work extremely well in the short term (hours to weeks/months), every long-term cardiac assist device on the market today is limited by the same two problems: infections caused by percutaneous drivelines and thrombotic events associated with the use of blood-contacting surfaces. A fundamental change in device design is needed to address both these problems and ultimately make a device that can support the heart indefinitely. Toward that end, several groups are currently developing devices without blood-contacting surfaces and/or extracorporeal power sources with the aim of providing a safe, tether-free means to support the failing heart over extended periods of time.

Cardiac Assist Devices: From Emergency Procedures to Regained Quality of Life:

Cardiac Assist Devices: From Emergency Procedures to Regained Quality of Life:

(1004) - Cardiac Rotational Mechanics as a Predictor of Favorable Functional Response Induced by Cardiac Assist Devices in Advanced Heart Failure

(1004) - Cardiac Rotational Mechanics as a Predictor of Favorable Functional Response Induced by Cardiac Assist Devices in Advanced Heart Failure

Work up for Advanced Therapies: Cardiac Transplantation and Left Ventricular Assist Devices

Work up for Advanced Therapies: Cardiac Transplantation and Left Ventricular Assist Devices

Time-Varying Hemodynamic Characteristics Simulation using Computerized Mock Circulatory Loop System with Servo Flow Regulator

A mock circulatory loop system has been developed to construct a simulator for trainees in cardiopulmonary bypass systems or to simulate a test environment for cardiac-assist devices. This paper proposes a computerized mock circulatory loop system whose node is modularized by using a servo control flow regulator to simulate dynamic change of the hemodynamic status. To observe the effect of time-varying resistance, one with hemodynamic properties, the proposed system replicates the planned cross-sectional areas of the outlet of a ventricular assist device in terms of voltage input of a servo valve. The experiment is performed (1) for steady-input commands of selected area sizes and (2) for dynamic commands such as monotonous increase and decrease, and oscillatory functions of the voltage input, and a computer program based on LabVIEW (National Instruments, Austin, USA) processes every measured data and control command to the servo valve. The results show that the pressure and flow at the target points with respect to time-varying resistance match intuitive estimation: the pressure at the outlet and the pressure drop between both sides of the valve increased and the flow at the outlet decreased for increased resistance.

Cardiac Rotational Mechanics as a Predictor of Favorable Functional and Structural Response After Mechanical Unloading With Cardiac Assist Devices in Advanced Heart Failure Patients

Cardiac Rotational Mechanics as a Predictor of Favorable Functional and Structural Response After Mechanical Unloading With Cardiac Assist Devices in Advanced Heart Failure Patients

Cardiac Assist Devices and Hemodialysis Catheter Procedures - What Do the Nephrologists Need to Know?

The use of ventricular assist devices (VAD) and total artificial heart (TAH) is increasing rapidly, and a large proportion of these device recipients already have or will develop severe renal dysfunction at the time of device implantation. As a consequence, nephrologists are becoming more and more involved in the care of this challenging population. As nephrologists take upon themselves many aspects of dialysis vascular access care, they need to be familiar with the special circumstances of performing hemodialysis catheter procedures in these patients. This review describes the important characteristics of these devices that have serious implications for the technique of placing or replacing dialysis catheters. These implications apply for both tunneled and nontunneled dialysis catheters and so concern all nephrologists, not only the interventionalists. We describe the important anatomical factors, anticoagulation management, device management, vascular access management and technical considerations of placing or replacing tunneled and nontunneled hemodialysis catheters from the perspective of a nephrologist establishing and maintaining lifesaving dialysis vascular access. Without a good understanding of these devices, serious consequences such as VAD rotor damage or blockage, or artificial heart valve blockage or damage can occur. These artificial devices are lifesaving, and any such complication is unacceptable. This review describes steps to minimize the risks.

Building a bridge to save a failing ventricle: radiologic evaluation of short- and long-term cardiac assist devices.

Heart failure is recognized with increasing frequency worldwide and often progresses to an advanced refractory state. Although the reference standard for treatment of advanced heart failure remains cardiac transplantation, the increasing shortage of donor organs and the unsuitability of many patients for transplantation surgery has led to a search for alternative therapies. One such therapy is mechanical circulatory support, which helps relieve the load on the ventricle and thereby allows it to recover function. In addition, there is increasing evidence supporting the use of mechanical devices as a bridge to recovery in patients with acute refractory heart failure. In this article, the imaging evaluation of various commonly used short- and long-term cardiac assist devices is discussed, and their relevant mechanisms of action and physiology are described. Imaging, particularly computed tomography (CT), plays a crucial role in preoperative evaluation for assessment of candidacy for implantation of a left ventricular assist device (LVAD) or total artificial heart (TAH). Also, echocardiography and CT are indispensable in assessment of complications associated with cardiac devices. Complications commonly associated with short-term assist devices include bleeding and malpositioning, whereas long-term devices such as LVADs may be associated with infection, pump thrombosis, and cannula malfunction, as well as bleeding. CT is also commonly performed for preoperative planning before LVAD or TAH explantation, replacement of a device or one of its components, and cardiac transplantation. Online supplemental material is available for this article.

Establishing the Framework for Tissue Engineered Heart Pumps.

Development of a natural alternative to cardiac assist devices (CADs) will pave the way to a heart failure therapy which overcomes the disadvantages of current mechanical devices. This work provides the framework for fabrication of a tissue engineered heart pump (TEHP). Artificial heart muscle (AHM) was first fabricated by culturing 4 million rat neonatal cardiac cells on the surface of a fibrin gel. To form a TEHP, AHM was wrapped around an acellular goat carotid artery (GCA) and a chitosan hollow cylinder (CHC) scaffold with either the cardiac cells directly contacting the construct periphery or separated by the fibrin gel. Histology revealed the presence of cardiac cell layer cohesion and adhesion to the fibrin gel scaffold, acellular GCA, and synthesized CHC. Expression of myocytes markers, connexin43 and α-actinin, was also noted. Biopotential measurements revealed the presence of ~2.5 Hz rhythmic propagation of action potential throughout the TEHP. Degradation of the fibrin gel scaffold of the AHM via endogenous proteases may be used as a means of delivering the cardiac cells to cylindrical scaffolds. Further development of the TEHP model by use of multi-stimulus bioreactors may lead to the application of bioengineered CADs.

Video Capsule Endoscopy is Safe and Effective in Hospitalized Patients With Implantable Cardiac Devices and Left Ventricular Assist Devices

Video Capsule Endoscopy is Safe and Effective in Hospitalized Patients With Implantable Cardiac Devices and Left Ventricular Assist Devices

(557) - In Vivo Testing of a New Permanent Atrial Connector for Cardiac Assist Devices

s S207 finding diminishes by 12 months. This suggests hemodynamic differences between axial flow and centrifugal flow may correspond with differences in functional capacity. Patient Demographics Gender (N)MaleFemale 21 (81%)5 ( 19%) Age (Average , Range) 51 (22-72) Etiology (N)Non-ischemic cardiomyopathyIschemic cardiomyopathy 19(73%) 7 (27%) Device (N)HMIIHW 18 (69%)8 (31%) Indication for Support (N)Bridge to TransplantDestination Therapy 20 (77%)6 (23%) Duration of Support in Months (Average, range) 27.7 (9-43.4)

Shear Stress, Energy Losses, and Costs: A Resolved Dilemma of Pulsatile Cardiac Assist Devices

Cardiac assist devices (CAD) cause endothelial dysfunction with considerable morbidity. Employment of pulsatile CAD remains controversial due to inadequate perfusion curves and costs. Alternatively, we are proposing a new concept of pulsatile CAD based on a fundamental revision of the entire circulatory system in correspondence with the physiopathology and law of physics. It concerns a double lumen disposable tube device that could be adapted to conventional cardiopulmonary bypass (CPB) and/or CAD, for inducing a homogenous, downstream pulsatile perfusion mode with lower energy losses. In this study, the device's prototypes were tested in a simulated conventional pediatric CPB circuit for energy losses and as a left ventricular assist device (LVAD) in ischemic piglets model for endothelial shear stress (ESS) evaluations. In conclusion and according to the study results the pulsatile tube was successfully capable of transforming a conventional CPB and/or CAD steady flow into a pulsatile perfusion mode, with nearly physiologic pulse pressure and lower energy losses. This represents a cost-effective promising method with low mortality and morbidity, especially in fragile cardiac patients.