Artificial Ventricle Research Articles

Modern strategy for the treatment of myocarditis in children

The article presents data on the current strategy for the treatment of myocarditis in children. The authors discuss the tactics of treatment of patients with unstable hemodynamics requiring emergency medical care using inotropic support. The possibilities of surgical methods of treatment of decompensated heart failure in myocarditis (artificial left ventricle, extracorporeal membrane oxygenation, heart transplantation) are clarified. Current approaches to the treatment of myocarditis with stable hemodynamics are described. Data on the effectiveness of angiotensin enzyme inhibitors and beta-blockers for the treatment of myocarditis in children are presented. Indications for immunosuppressive and immunomodulatory therapy are discussed

Hemodynamic characterization of the Realheart® total artificial heart with a hybrid cardiovascular simulator.

Heart failure is a growing health problem worldwide. Due to the lack of donor hearts there is a need for alternative therapies, such as total artificial hearts (TAHs). The aim of this study is to evaluate the hemodynamic performance of the Realheart® TAH, a new 4-chamber cardiac prosthesis device. The Realheart® TAH was connected to a hybrid cardiovascular simulator with inflow connections at the left/right atrium, and outflow connections at the ascending aorta/pulmonary artery. The Realheart® TAH was tested at different pumping rates and stroke volumes. Different systemic resistances (20.0-16.7-13.3-10.0 Wood units), pulmonary resistances (6.7-3.3-1.7 Wood units), and pulmonary/systemic arterial compliances (1.4-0.6ml/mmHg) were simulated. Tests were also conducted in static conditions, by imposing predefined values of preload-afterload across the artificial ventricle. The Realheart® TAH allows the operator to finely tune the delivered flow by regulating the pumping rate and stroke volume of the artificial ventricles. For a systemic resistance of 16.7 Wood units, the TAH flow ranges from 2.7±0.1 to 6.9±0.1L/min. For a pulmonary resistance of 3.3 Wood units, the TAH flow ranges from 3.1±0.0 to 8.2±0.3L/min. The Realheart® TAH delivered a pulse pressure ranging between ~25mmHg and ~50mmHg for the tested conditions. The Realheart® TAH offers great flexibility to adjust the output flow and delivers good pressure pulsatility in the vessels. Low sensitivity of device flow to the pressure drop across it was identified and a new version is under development to counteract this.

Development of an electrode system for continuous measurement of the volume of an AHV

Mechanical circulatory assistance devices are vital for the patients with end-stage heart failure, who require heart transplantation but are in a waiting list due to the shortage of donor organs. This makes the development of the advanced MCS devices and artificial heart ventricles a crucial task. The systems for the dynamic and adaptive control of circulation parameters are required. AHV liquid volume measurement units must be developed to create such systems. Objective – Determination of the optimal electrode system for the AHV liquid volume measurement unit based on the electrical impedance measurements. The most significant geometrical parameters of the electrode systems for the impedance based AHV liquid volume measurement are determined. The optimal values of the geometrical parameters were found for the system of dynamic AHV liquid volume measurement. Results were confirmed by the numerical and experimental studies. The obtained values of the optimal geometrical parameters of electrode systems will be used in development of biotechnical system of adaptive AHV control.

Abstract 16945: Total Artificial Heart Implantation in Patients With Intractable Ventricular Arrhythmias

Ventricular arrhythmias (VAs) are pathological rhythms that are often incompatible with life and require decisive intervention. If the rhythm is refractory to treatment or causes hemodynamic compromise, mechanical support devices may be required. Oftentimes, patients with underlying heart failure do very poorly with VAs, requiring a higher level of support than can be achieved by most devices, with the exception of LVADs and TAHs. Mechanistically, a TAH is an orthotopic pneumatic biventricular mechanical support device that requires removal of the native cardiac ventricles and replacement with two artificial ventricles. Due to the nature of the procedure, the ventricular substrate, which causes VAs, is removed and the patient receives biventricular mechanical support. This case series retrospectively follows eight patients requiring implantation of a TAH due to intractable VAs between 06/2008 and 03/2017 at VCU Health. On arrival, all patients were in multiorgan failure and requiring hemodynamic support, including a varied combination of support devices, inotropes, and/or pressors. The median time of admission to implantation was 12.6 days. Major adverse events included cerebral vascular attack (CVA), significant bleeding requiring surgical intervention, and surgical site infection. Three patients had ischemic CVAs, three had significant mediastinal hematoma resulting in tamponade requiring intervention, and two had significant operative site infections requiring antibiotics and surgery. Of the original eight patients, six went on to undergo an orthotopic heart transplant, all were alive at one year follow-up. While adverse events can be serious and should be considered when evaluating for implantation, the use of a TAH can be beneficial in patients with intractable VAs and can be used to successfully stabilize patients who would otherwise perish.

First experience in implantation of a mechanical circulatory support device based on a disk-type pump: an acute experiment

Objective: to carry out the implantation of an artificial left ventricle of the heart based on a disk-type pump in an acute experiment on a large mammal (mini-pig). Materials and methods. To test the surgical technique of implantation and assess the biocompatibility of the apparatus for mechanical support of blood circulation based on a viscous friction pump, an acute experiment was conducted on an animal. A large mammal (mini-pig weighing 90 kg) was used as an experimental model. The implantation of the pump was performed extracorporeally according to the scheme «the apex of the left ventricle – the descending thoracic aorta». During the experiment, invasive blood pressure, central venous pressure, cardiac arrhythmias, body temperature, blood gas composition, activated coagulation time were monitored. Under the control of transesophageal echocardiography, the pump operation mode was set with parameters – speed 2400–2600, productivity 4 ± 0.5 l/min, average IAD – 70–80 mm Hg. Results. In the course of the experiment, the fundamental possibility of using the developed disk-type pump as a device for supporting blood circulation was proved. For 4 hours, the pump provided adequate hemodynamic parameters with an average productivity of 4 ± 0.5 l/min and 2500 rpm. After 4 hours of operation of the pump in the conditions of inactivated heparin (AST – 114 sec), no blood clots were found between the pump disks. Conclusion The hemodynamics feature of the disk pump allows you to develop sufficient performance parameters to ensure adequate blood circulation. The mechanism of action of the «boundary layer» minimizes the risk of blood clots in the pump cavity. However, the topographic and anatomical features of the pig’s body do not allow experiments with a long observation period.

P239 Total artificial heart implantation as a bridge to candidacy - an approach to treating primary cardiac sarcoma?

Abstract Background Primary cardiac tumors are rare entities, only 25% of them are malignant. Most common malignant neoplasms of the heart are sarcomas - aggressive tumors with a high rate of local recurrence and systemic metastases. They may lead to a rapid clinical deterioration and sudden circulatory collapse due to obstruction of the intracardiac outflow tract. Most patients affected are younger than 65 years of age. Early diagnosis of cardiac tumors is challenging, echocardiography remains a mainstay of their evaluation. The prognosis is very poor, most patients succumb to disease within months of diagnosis. Complete surgical resection and adjuvant chemotherapy offers palliation and improves survival. Total artificial heart implantation (TAH) allows through, radical resection of large tumors yielding the best possible outcome. Case presentation A 58-year-old male patient with a history of hypertension was admitted to our hospital with a chief complaint of worsening dyspnea and fatigue for last several weeks. Echocardiogram demonstrated a large cardiac mass with abundant vascular supply that incorporated the whole right ventricle and intraventricular septum, extended to the tricuspid valve, infiltrated the left ventricle apex and the base of posterior tricuspid leaflet. The right ventricle cavity was slit-like with small gradient in the outflow track. Cardiac magnetic resonance suggested angiosarcoma or lymphoma. PET-CT did not reveal any extracardiac metastases at that time. The case was discussed at our multidisciplinary cardio-oncology conference. The radical resection of the mass with subsequent TAH implantation was decided upon in high-risk setting, with feasible long-term survival, including eventual consideration for cardiac transplantation (HTX). Native ventricles were excised at the atrioventricular level down to the annulus of the mitral and tricuspid valves. The artificial ventricles were connected to the atrial remnants. The ascending aorta and the main pulmonary artery were dissected close to the valves and connected to outflow grafts. Histopathologic examination of the mass demonstrated angiosarcoma. The patient was started on paklitaksel. After completion of his chemotherapy regimen his eligibility for HTX will be reevaluated. Conclusion Diagnosis and therapy of sarcomas are challenging. Their rarity makes it difficult to standardize therapy. There is few evidence available in literature to guide the treatment of such patients. Case-specific, heart-team-based strategy must be adopted to aid decision making in this rare cases. Sarcomas are lethal, develop rapidly and affect fairly young patients. Prompt surgical resection with subsequent TAH implantation and adjuvant chemotherapy seems ideal in this situation as it offers a possible cure. It gives a slim chance of long-term survival after consecutive HTX for chemotherapy responders. Abstract P239 Figure. Angiosarcoma in TTE, MRI and TEE.

Asistencia mecánica circulatoria II Ventrículos artificiales

Asistencia mecánica circulatoria II Ventrículos artificiales

Numerical Approach to Study the Behavior of an Artificial Ventricle: Fluid-Structure Interaction Followed By Fluid Dynamics With Moving Boundaries.

Heart failure is a progressive and often fatal pathology among the main causes of death in the world. An implantable total artificial heart (TAH) is an alternative to heart transplantation. Blood damage quantification is imperative to assess the behavior of an artificial ventricle and is strictly related to the hemodynamics, which can be investigated through numerical simulations. The aim of this study is to develop a computational model that can accurately reproduce the hemodynamics inside the left pumping chamber of an existing TAH (Carmat-TAH) together with the displacement of the leaflets of the biological aortic and mitral valves and the displacement of the pericardium-made membrane. The proposed modeling workflow combines fluid-structure interaction (FSI) simulations based on a fixed grid method with computational fluid dynamics (CFD). In particular, the kinematics of the valves is accounted for by means of a dynamic mesh technique in the CFD. The comparison between FSI- and CFD-calculated velocity fields confirmed that the presence of the valves in the CFD model is essential for realistically mimicking blood dynamics, with a percentage difference of 2% during systole phase and 13% during the diastole. The percentage of blood volume in the CFD simulation with a shear stress above the threshold of 50Pa is less than 0.001%. In conclusion, the application of this workflow to the Carmat-TAH provided consistent results with previous clinical studies demonstrating its utility in calculating local hemodynamic quantities in the presence of complex moving boundaries.

Measurement of shape mapping accuracy of a flaccid membrane of a heart assist pump

The paper presents the research results which are a continuation of work on the use of image processing techniques to determine the membrane shape of the artificial ventricle. The studies were focused on developing a technique for measuring the accuracy of the membrane shape mapping. It is important in view of ensuring the required accuracy of determining the instantaneous stroke volume of controlled pneumatic artificial ventricular. Experiments were carried out on the models of convex, concave, and flat membranes. The purpose of the research was to obtain a numerical indicator, which will be used to evaluate the options to improve mapping techniques of the membrane shape. Keywords: accuracy measurement, membrane shape mapping, optical sensor

Optical distortion compensation in the visual measurement with the new Depth From Defocus method

The paper presents new approach to compensation the inaccuracy of shape mapping of the flaccid membrane used in the extracorporeal pneumatic heart assist pump. The original shape of the membrane was determined using specially developed DFD type method. The major problems affecting the inaccuracy of mapping the membrane result from the phenomenon of optical distortion. The invented approach to compensate for optical distortion in the process of visual measurement as well as the results obtained were presented. Full Text: PDF ReferencesK. Murawski, Method of measuring the distance using one camera, Patent Application No P.408076 (2014) - in Polish. DirectLink K. Murawski, M. Murawska, T. Pustelny, The system and method of determining the shape of the membrane pneumatic pump of extracorporeal heart assist device, Patent Application No P.414104 (2015) - in Polish. DirectLink M. Gawlikowski, T. Pustelny, R. Kustosz, "The physical parameters estimation of physiologically worked heart prosthesis", Journal de Physique IV France 137, 73 (2006). CrossRef K. Murawski, "Measurement of Membrane Displacement Using a Motionless Camera", Acta Phys. Pol. A 128(1), 10 (2015). CrossRef K. Murawski, "Measurement of Membrane Displacement with a Motionless Camera Equipped with a Fixed Focus Lens", Metrology and Measurement Systems 22(1), 69 (2015). CrossRef K. Murawski, A. Arciuch, T. Pustelny, "Study of distance range visual measurement in the new Depth From Defocus method", Phot. Lett. Poland 8, 2 (2016). CrossRef L. Grad, K. Murawski, W. Sulej, "Research to improve the accuracy of determining the stroke volume of an artificial ventricle using the wavelet transform", Proc. SPIE 10455, 1045509 (2017). CrossRef W. Sulej, K. Murawski, "The membrane shape mapping of the artificial ventricle in the actual dimensions", Proc. FedCSIS ACSIS 11, 675 (2017). CrossRef W. Sulej, L. Grad, K. Murawski, "The technique of accuracy measurement of membrane shape mapping of an artificial ventricle", Proc. SPIE 10455, 104550B (2017). CrossRef

RECONSTRUCTIVE ONE- AND TWO STEP JEJUNOGASTROPLASTY AFTER TOTAL GASTRECTOMY IN BLEEDING GASTRIC CANCER

Relevance. Modern and topical questions of surgical treatment of acute bleeding gastric cancer are considered with the use of innovative hardware technologies of operative interventions with the formation of an artificial ventricle (jejunogastroplasty) after total gastrectomy (GE).
 Objective. Development and introduction of new technologies and methods of one-stage and two-stage reconstructive jejunogastroplasty (JGP), which can improve the functional results of total gastrectomy for acute bleeding gastric cancer.
 Materials and methods. Are analyzed 30 patients after the GE in conjunction with jejunogastroplasty (JGP) for bleeding gastric cancer. Men were 22 (73 %), women – 8 (27 %). In 68 % of patients who underwent JGP verified III st. and IV st. neoplastic process. When forming an artificial stomach (reconstructive JGP) used a variety of options and technologies: JGP manually performed in 3 (10 %), hardware – in 27 (90 %).
 Results. JGP by Roux loop applied in 6 (20 %), Ω-loop JGP with Brownian anastomosis – in 16 (53 %), and in 8 (27 %) performed reconstructive hardware JGP in a functionally advantageous embodiment including of the duodenum. In 28 patients lymph node dissection performed in the amount of D2, two – D1 using an ultrasonic scalpel and the machine welding of biological tissues. Deaths were not. Developed and implemented the concept two-step JGP after total GE at bleeding gastric cancer. In the first phase, the GE with lymph node dissection. In developing dumping syndrome, nongastric fatigue, weight loss, violation digestiv tract function in the postoperative period and in the absence of data on the progression of the tumor process in the second phase after 4-6 months (sometimes 1-1,5 years) after total GE undertaken reconstructive JGP with the creation of artificial jejunum reservoir. Developed sixteen variants hardware reconstructive JGP without including and with the including of the duodenum in the digestive transit. The best functional results obtained after reconstructive JGP including of the duodenum.
 Conclusions. In patients young and middle age after total GE at bleeding gastric cancer it is advisable to complement perfoming JGP including of the duodenum. The use of one- and two step JGP after total GE improves the quality of life of the patients in the late postoperative period.

Mechanical circulation support of the treatment for children with end-stage chronic heart failure

Over the last decades mechanical circulation support has become one of the most effective treatment methods for patients with terminal heart failure. Unfortunately, in pediatrics this method is generally used on a short-term basis and includes, first of all, extracorporeal membranous oxygenation and left ventricular bypass by means of the extracorporeal centrifugal pumps. Nevertheless, using of these methods in children allowed considerably reducing mortality on the waiting list for heart transplant. Today, practically the only method of long term mechanical circulatory support in newborns and children at an early age being used is the system of paracorporeal artificial ventricles EXCOR, the usage of which results in larger problems of thrombosis. There is little clinical experience in using of the fully implanted systems developed for adults in older children. Therefore, as shown in the present review, the problem of creating long term circulatory support systems for newborns and younger children on the basis of the implanted pumps continues to be relevant.

Synergetic Control of Magnetic Bearings in Artificial Heart Ventricle Rotor

This article reviews the problem of centering the rotor of an axial pump of the artificial heart ventricle (AHV) in a magnetic suspension. The small gap of the flowing part, high rotor speed, necessary service life of the AHV device, and its reliability and functionality introduce high demands on the control system of the rotor with magnetic bearings. This article proposes a synthesis of the control laws of the AHV with magnetic bearings based on the ADAR method (analytical design of aggregated regulators) of synergetic control theory and presents possibilities and prospects of applying the proposed control scheme.

Newly Shaped Intra-Aortic Balloons Improve the Performance of Counterpulsation at the Semirecumbent Position: An In Vitro Study.

The major hemodynamic benefits of intra‐aortic balloon pump (IABP) counterpulsation are augmentation in diastolic aortic pressure (P aug) during inflation, and decrease in end‐diastolic aortic pressure (ΔedP) during deflation. When the patient is nursed in the semirecumbent position these benefits are diminished. Attempts to change the shape of the IAB in order to limit or prevent this deterioration have been scarce. The aim of the present study was to investigate the hemodynamic performance of six new IAB shapes, and compare it to that of a traditional cylindrical IAB. A mock circulation system, featuring an artificial left ventricle and an aortic model with 11 branches and physiological resistance and compliance, was used to test one cylindrical and six newly shaped IABs at angles 0, 10, 20, 30, and 40°. Pressure was measured continuously at the aortic root during 1:1 and 1:4 IABP support. Shape 2 was found to consistently achieve, in terms of absolute magnitude, larger ΔedP at angles than the cylindrical IAB. Although ΔedP was gradually diminished with angle, it did so to a lesser degree than the cylindrical IAB; this diminishment was only 53% (with frequency 1:1) and 40% (with frequency 1:4) of that of the cylindrical IAB, when angle increased from 0 to 40°. During inflation Shape 1 displayed a more stable behavior with increasing angle compared to the cylindrical IAB; with an increase in angle from 0 to 40°, diastolic aortic pressure augmentation dropped only by 45% (with frequency 1:1) and by 33% (with frequency 1:4) of the drop reached with the cylindrical IAB. After compensating for differences in nominal IAB volume, Shape 1 generally achieved higher P aug over most angles. Newly shaped IABs could allow for IABP therapy to become more efficient for patients nursed at the semirecumbent position. The findings promote the idea of personalized rather than generalized patient therapy for the achievement of higher IABP therapeutic efficiency, with a choice of IAB shape that prioritizes the recovery of those hemodynamic indices that are more in need of support in the unassisted circulation.

Development of Artificial Ventricles for Modeling the Cardiovascular System

The article presents the results of development and experimental studies of artificial ventricles used for modeling the cardiovascular system. The ventricle is divided into two hemispheres separated by a membrane, ensuring the necessary level of contractility of the artificial ventricle and separating its hydraulic and pneumatic components. The study considered two versions of the ventricle, with mechanical check valves (Vesta Trading, Shcherbinka, Moscow, Russia) and bicuspid artificial valves (ZAO NPP MedEng, Penza, Russia) as aortic and mitral valves. The designed ventricles were compared with a reference, which was represented by a Medos VAD membranous artificial ventricle (Medos Medizintechnik AG, Stolberg, Germany).

Simulator for Modeling the Cardiovascular System for Testing Circulatory Assist Devices

A simulator of the human cardiovascular system intended for testing circulatory assist devices is described. The device is a hydraulic circuit that simulates the greater and lesser circulation. It consists of two artificial ventricles, four closed reservoirs, a pneumatic control system, a flow sensor, ten liquid pressure sensors, and two inductors to provide vascular resistance. The device has hydrodynamic characteristics comparable to that of the human heart. It can be used for preclinical testing of circulatory assist devices of the left ventricle, right ventricle, or both ventricles of the heart, and of the completely artificial heart.

The Research of Influence of Blood upon the Dynamics of Artificial Ventricle Rotor on Active Magnetic Bearings

The Research of Influence of Blood upon the Dynamics of Artificial Ventricle Rotor on Active Magnetic Bearings

Surgical implantation of the CardioWest Total Artificial Heart.

The CardioWest Total Artificial Heart (CW-TAH) is a pneumatically driven pump that completely replaces the patient’s native ventricles orthotopically. The device weighs 160 g and consists of two artificial ventricles, four Medtronic Hall tilting disk valves, two membranes, and two drivelines tunneled through the skin, which connect the ventricles to an external console generating pulsatile flow (1). At maximum stroke volume (close to 70 mL), it delivers a cardiac output between seven and nine litres per minute. Variations in cardiac output are determined by variations in venous return and peripheral resistance linked to the patient’s position and level of physical activity (2). The CW-TAH is indicated for use in patients with refractory cardiac failure as a bridge to transplantation, and when used for this indication, improves survival to transplant (3). Portable drivers have been approved in both Europe and the United States to allow stable patients to be discharged home while awaiting their transplant (4).

System overview of the fully implantable destination therapy--ReinHeart-total artificial heart.

Owing to the lack of suitable allografts, the demand for long-term mechanical circulatory support in patients with biventricular end-stage heart failure is rising. Currently available Total Artificial Heart (TAH) systems consist of pump units with only limited durability, percutaneous tubes and bulky external equipment that limit the quality of life. Therefore we are focusing on the development of a fully implantable, highly durable destination therapy total artificial heart. The ReinHeart-TAH system consists of a passively filling pump unit driven by a low-wear linear drive between two artificial ventricles, an implantable control unit and a compliance chamber. The TAH is powered by a transcutaneous energy transmission system. The flow distribution inside the ventricles was analysed by fluid structure interaction simulation and particle image velocimetry measurements. Along with durability tests, the hydrodynamic performance and flow balance capability were evaluated in a mock circulation loop. Animal trials are ongoing. Based on fluid structure interaction simulation and particle image velocimetry, blood stagnation areas have been significantly reduced. In the mock circulation loop the ReinHeart-TAH generated a cardiac output of 5 l/min at an operating frequency of 120 bpm and an aortic pressure of 120/80 mmHg. The highly effective preload sensitivity of the passively filling ventricles allowed the sensorless integration of the Frank Starling mechanism. The ReinHeart-TAH effectively replaced the native heart's function in animals for up to 2 days. In vitro and in vivo testing showed a safe and effective function of the ReinHeart-TAH system. This has the potential to become an alternative to transplantation. However, before a first-in-man implant, chronic animal trials still have to be completed.

Mechanical Circulatory Support for Advanced Heart Failure

After nearly 50 years of clinical development, durable mechanical circulatory support (MCS) devices are widely available for patients with advanced heart failure. The field of circulatory support has matured dramatically in recent years, thanks to the advent of smaller, rotary pumps. The resulting transition away from older pulsatile devices has been swift. Accelerated use of continuous-flow left ventricular assist devices (LVADs) for long-term support has changed the face of advanced heart failure care. MCS candidate selection, risk stratification, and management strategies are evolving in tandem with new pump technology, producing a shift in the profiles of patients being considered for MCS. Timely referral for MCS evaluation and appropriate implantation now depends on familiarity with recent advances in pump design and clinical outcomes. This review, the first in a series on Advances in Mechanical Circulatory Support , will focus on durable intracorporeal LVADs used in adults with advanced heart failure, and highlight the evolution in both patients and technology. The modern era of cardiac surgery began in 1953 with the first clinical use of cardiopulmonary bypass, allowing increasingly complex operations and laying the foundation for circulatory assist devices.1 Shortly after its invention, the heart-lung machine began to be used to support patients with postcardiotomy cardiogenic shock to facilitate recovery after failed operations. By the 1960s, simple cardiac assist devices began to replace cardiopulmonary bypass for the treatment of postcardiotomy shock (Figure 1). The first clinical use of an implantable artificial ventricle was reported by Liotta et al2 in 1963. This primitive ventricular assist device (VAD) consisted of a pneumatically driven, tubular displacement pump with a valved conduit connecting the left atrium to the descending thoracic aorta. The pump provided partial left ventricular bypass for 4 days after postoperative cardiac arrest before the patient died of multiorgan failure. Inspired by …