Postoperative management and nursing care after implantation of a total artificial heart: Scoping review

INTRODUCTION

End-stage heart failure (HF) is a condition whose only successful long-term treatment, with a survival of more than 10 years, is heart transplantation. However, limited organ availability and the progressive increase in the number of patients with advanced HF have served as an impetus for the development of implantable mechanical assistive devices.

AIM

To provide an overview of postoperative management and nursing care after the implementation of a Total Artificial Heart (TAH).

METHODS

A scoping review was carried out by consulting the PUBMED, CINAHL, and COCHRANE databases. From all the documents located, information was extracted on the date of publication, country of publication, type of study, and results of interest to answer the research question. In addition, the degree of recommendation was identified.

RESULTS

Twenty-three documents were included in the scoping review. Results were classified in relation to: 1) description of the CAT SynCardia®; 2) nursing care in the immediate postoperative period (management of the device and management of hematological, infectious, nephrological, nutritional complications, related to immobilization, sleep-rest disturbances, psychological disorders, and patient and family education); and 3) follow-up at home.

CONCLUSIONS

The complexity of implantation of the TAH, the multiple related complications that can arise during this process, both in the immediate post-operative and late, require a standardised and multidisciplinary management. The absence of standardised protocols raises the need for future studies to measure the effectiveness of care in patients with TAH. A multidisciplinary approach is crucial. Nurses must acquire autonomy and involvement in decision-making and develop competencies to address the patient's and family's physiological and psychosocial needs.

In-hospital complications associated with total artificial heart implantation in the United States between 2004 to 2011

OBJECTIVE

Total artificial heart (TAH) utilization has increased over the recent years. The goal of this study was to evaluate the trend of artificial hearts used in the USA with its associated morbidity and mortality based on a large in-hospital database.

MATERIALS AND METHODS

Using a very large nationwide inpatient samples (NIS) database, we used ICD-9 code for a total artificial heart. We evaluated the utilization of this device over the years studied. Furthermore, we evaluated any associated complications and mortality in patients receiving this device.

RESULTS

From 2004 until 2011, the rate of total artificial heart implants increased over the years from 5 in 2004 to the highest of 26 in 2011 across the United State. TAH was insesrted in 75 patients. Death was reported in 22 patients (29.3%). Acute renal failure was the most common complication (69.3%). This is followed by post-operative infectious complications (28.0%), acute renal failure requiring dialysis (16%), bleeding complications requiring blood transfusion (14.7%) respiratory complications (6.7%), and stroke/TIA (4.0%). There was no post-operative deep vein thrmobosis or pulmonary embolism.

CONCLUSIONS

The use of total artificial heart has increased in the United State steadily with substantial morbidity and mortality associated with this device.

Biomechanical properties of erythrocytes circulating in artificial hearts measured by dielectrophoretic method

Blood damage is recognized as one of the major problems caused by non-physiological shear force induced by artificial hearts. At present, the generally accepted manifestation of mechanical blood damage is the amount of free hemoglobin released into the blood. However, there is little research on the changes of blood cell state after circulating in artificial hearts at the single-cell level. It is well known that the mechanical properties of cells are of enormous relevance in the regulation of cellular physiological and pathological processes. In this regard, it is highly needed to study the mechanical properties of blood cells affected by non-physiological shear force. In this paper, a dielectrophoresis-based method of measuring the mechanical properties of erythrocytes circulating in artificial hearts was proposed, which was quantified with some crucial parameters such as strain, elongation index (EI), and Young's modulus. Experimental results indicated that with the increase of the working time of artificial hearts, the deformability of erythrocytes decreased, the stiffness substantially increased, and the mechanical stability decreased, particularly at long exposure times. The proposed method provides a deep insight into the mechanism of subhemolytic damage at the single-cell level and has a great potential to serve as a new tool for in vitro evaluation of potential blood damage in artificial hearts.

On the understanding of dielectric elastomer and its application for all-soft artificial heart

Although dielectric elastomer (DE) with substantial actuated strain (AS) has been reported 20 years ago, its scientific understanding remains unclear. The most accepted theory of DE, which is proposed in 2000, holds the view that AS of DE is induced by the Maxwell stress. According to this theory, materials have similar ratios of permittivity and Young's modulus should have similar AS, while the experimental results are on contrary to this theory, and the experimental AS has no relationship with ideal AS. Here, a new dipole-conformation-actuated strain cross-scale model is proposed, which can be generally applied to explain the AS of DE without pre-strain. According to this model, several characteristics of an ideal DE are listed in this work and a new DE based on polyphosphazene (PPZ) is synthesized. The AS of PPZ can reach 84% without any pre-strain. At last, a PPZ-based all soft artificial heart (ASAH) is built, which works in the similar way with natural myocardium, indicating that this material has great application potential and possibility in the construction of an ASAH for heart failure (HF) patients.

New treatment strategy for severe heart failure: combination of ventricular assist device and regenerative therapy

Heart transplantation and ventricular assist device for the patients with end-stage heart failure are limited by availability and durability due to limited donor or device-related complication. Thus, complementation or a new alternative is needed for the treatment of severe heart failure. Based on the results of basic experiments, we applied skeletal myoblast cell sheet transplantation in a clinical setting using cell-sheet methods with temperature-responsive dish for the treatment of heart failure patient from 2007. After confirming the safety of this treatment, we started a clinical trial of myoblast cell sheet transplantation as sole therapy. According to these results, in 2015, myoblast cell sheet transplantation with ischemic cardiomyopathy was approved by the Japanese government and now this treatment was covered by Japanese health insurance. Here we report our approach and future perspective of cardiac regenerative therapy using this new treatment method for severe heart failure including new strategy incorporating regenerative therapy in the conventional treatment of heart failure including VAD and heart transplantation.

A case of left ventricular assist device application for chemotherapy-related cardiomyopathy caused by trastuzumab and anthracycline

Left ventricular assist device (LVAD) is an established therapy for patients with severe heart failure. Because the incidence of cardiotoxicity owing to anticancer agents is low, it is difficult to predict the recovery prospects when the cause of heart failure is due to anticancer agents. In this context, cancer patients who present with severe symptoms of heart failure and who fail medical therapy for heart failure may pose a dilemma, especially in countries such as Japan where implantable LVADs are not approved for purposes other than bridging to transplant. Recently, we encountered a 32-year-old woman with chemotherapy-related cardiomyopathy that developed after anticancer treatment using trastuzumab and anthracycline. LVAD therapy was the only option to save the young woman. The patient received an extracorporeal LVAD, her cardiac function gradually recovered while on support, and the device was successfully removed.

In Vitro Study on the Dynamics of Blood Flow Impelled by an Alternating Current Magnetohydrodynamic Blood Pump

Artificial hearts are effective devices to treat heart failure in clinical practice and can be divided into two categories: artificial hearts and ventricular assist devices. The goal of this work was to investigate the fluidity and biological changes of in vitro sheep blood using a novel alternating current (AC) magnetohydrodynamic blood pump (central magnetic intensity: 0.9 T, alternating current frequency of the electric motor: 0-80 Hz). Blood samples were collected from five sheep and were divided into two groups: the control group (no exposure to an external magnetic field) and the exposed group (3 h of exposure to an alternating magnetic field). The blood cell counts, changes in blood viscosity, and ultrastructural changes of the blood cells under transmission electron microscopy were investigated. This study demonstrated several findings: (i) Continuous sheep blood flow can be achieved; (ii) The blood cell counts remained unchanged after 3 h of exposure to an alternating magnetic field; (iii) Compared with the control group, the high- and low-shear viscosities of the whole blood from the sheep significantly decreased after 3 h of exposure to an alternating magnetic field (P < 0.05 and P < 0.01, respectively). Plasma viscosity was significantly reduced after exposure to high-intensity alternating magnetic fields (P < 0.001); (iv) The cytoplasm of blood cells (especially erythrocytes) became lighter in color in the exposure group compared to the control group, and "beads-on-string" aggregations of black particles appeared. This work provides detailed and reliable scientific research data for the development of this type of blood pump, which may serve as a transition to the clinical artificial heart.

Additive manufacturing applications in cardiology: A review

BACKGROUND

Additive manufacturing (AM) has emerged as a serious planning, strategy, and education tool in cardiovascular medicine. This review describes and illustrates the application, development and associated limitation of additive manufacturing in the field of cardiology by studying research papers on AM in medicine/cardiology.

METHODS

Relevant research papers till August 2018 were identified through Scopus and examined for strength, benefits, limitation, contribution and future potential of AM. With the help of the existing literature & bibliometric analysis, different applications of AM in cardiology are investigated.

RESULTS

AM creates an accurate three-dimensional anatomical model to explain, understand and prepare for complex medical procedures. A prior study of patient's 3D heart model can help doctors understand the anatomy of the individual patient, which may also be used create training modules for institutions and surgeons for medical training.

CONCLUSION

AM has the potential to be of immense help to the cardiologists and cardiac surgeons for intervention and surgical planning, monitoring and analysis. Additive manufacturing creates a 3D model of the heart of a specific patient in lesser time and cost. This technology is used to create and analyse 3D model before starting actual surgery on the patient. It can improve the treatment outcomes for patients, besides saving their lives. Paper summarised additive manufacturing applications particularly in the area of cardiology, especially manufacturing of a patient-specific artificial heart or its component. Model printed by this technology reduces risk, improves the quality of diagnosis and preoperative planning and also enhanced team communication. In cardiology, patient data of heart varies from patient to patient, so AM technologies efficiently produce 3D models, through converting the predesigned virtual model into a tangible object. Companies explore additive manufacturing for commercial medical applications.

Histological investigation of the titanium fiber mesh with one side sealed with non-porous material for its application to the artificial heart system

In this study, we investigated tissue-inducing characteristics of a titanium fiber mesh disk with one surface sealed with a non-porous material. We used sintered titanium fiber mesh (Hi-Lex Co., Zellez™, Hyogo, Japan) having a titanium fiber diameter of 50 µm and volumetric porosity of the titanium fiber mesh of 87% with an average pore size of 200 µm. The titanium fiber mesh is disk-shaped with a dimeter of 5 mm and a thickness of 1.5 mm. One side of the titanium fiber mesh disk was sealed with silicone rubber adhesive that has no venomousness and the sealed titanium fiber mesh disks were implanted in rats under the skin of the dorsal region, and they were extracted in the 4th and 12th postoperative weeks. We investigated the distribution of capillaries; also we estimated the extent of the spread of oxygen from capillaries using the diffusion equation. Microscopic observation showed that the distribution of capillaries was mainly confined to the area around the sealed titanium fiber mesh disk and that connective tissue inside the sealed titanium fiber mesh disk seemed to be in a poor condition. From estimation of the extent of the spread of oxygen from capillaries, an area in which oxygen was poorly supplied may exist in the center of the sealed titanium fiber mesh disk. In conclusion, for application of the sealed titanium fiber mesh to an artificial heart system, the thickness of the titanium fiber mesh is an important factor for keeping the inside tissue in a healthy condition.

Measurement of hemodynamic changes with the axial flow blood pump installed in descending aorta

We have developed various axial flow blood pumps to realize the concept of the Valvo pump, and we have studied hemodynamic changes under cardiac assistance using an axial flow blood pump in series with the natural heart. In this study, we measured hemodynamic changes of not only systemic circulation but also cerebral circulation and coronary circulation under cardiac support using our latest axial flow blood pump placed in the descending aorta in an acute animal experiment. The axial flow blood pump was installed at the thoracic descending aorta through a left thoracotomy of a goat (43.8 kg, female). When the pump was on, the aortic pressure and aortic flow downstream of the pump increased with preservation of pulsatilities. The pressure drop upstream of the pump caused reduction of afterload pressure, and it may lead to reduction of left ventricular wall stress. However, cerebral blood flow and coronary blood flow were decreased when the pump was on. The axial flow blood pump enables more effective blood perfusion into systemic circulation, but it has the potential risk of blood perfusion disturbance into cerebral circulation and coronary circulation. The results indicate that the position before the coronary ostia might be suitable for implantation of the axial flow blood pump in series with the natural heart to avoid blood perfusion disturbances.

Novel technique for airless connection of artificial heart to vascular conduits

Successful implantation of a total artificial heart relies on multiple standardized procedures, primarily the resection of the native heart, and exacting preparation of the atrial and vascular conduits for pump implant and activation. Achieving secure pump connections to inflow/outflow conduits is critical to a successful outcome. During the connection process, however, air may be introduced into the circulation, traveling to the brain and multiple organs. Such air emboli block blood flow to these areas and are detrimental to long-term survival. A correctly managed pump-to-conduit connection prevents air from collecting in the pump and conduits. To further optimize pump-connection techniques, we have developed a novel connecting sleeve that enables airless connection of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) to the conduits. In this brief report, we describe the connecting sleeve design and our initial results from two acute in vivo implantations using a scaled-down version of the CFTAH.

Electrical characteristic of the titanium mesh electrode for transcutaneous intrabody communication to monitor implantable artificial organs

We have developed a tissue-inducing electrode using titanium mesh to obtain mechanically and electrically stable contact with the tissue for a new transcutaneous communication system using the human body as a conductive medium. In this study, we investigated the electrical properties of the titanium mesh electrode by measuring electrode-tissue interface resistance in vivo. The titanium mesh electrode (Hi-Lex Co., Zellez, Hyogo, Japan) consisted of titanium fibers (diameter of 50 μm), and it has an average pore size of 200 μm and 87 % porosity. The titanium mesh electrode has a diameter of 5 mm and thickness of 1.5 mm. Three titanium mesh electrodes were implanted separately into the dorsal region of the rat. We measured the electrode-electrode impedance using an LCR meter for 12 weeks, and we calculated the tissue resistivity and electrode-tissue interface resistance. The electrode-tissue interface resistance of the titanium mesh electrode decreased slightly until the third POD and then continuously increased to 75 Ω. The electrode-tissue interface resistance of the titanium mesh electrode is stable and it has lower electrode-tissue interface resistance than that of a titanium disk electrode. The extracted titanium mesh electrode after 12 weeks implantation was fixed in 10 % buffered formalin solution and stained with hematoxylin-eosin. Light microscopic observation showed that the titanium mesh electrode was filled with connective tissue, inflammatory cells and fibroblasts with some capillaries in the pores of the titanium mesh. The results indicate that the titanium mesh electrode is a promising electrode for the new transcutaneous communication system.

Future Prospects for the Total Artificial Heart

A total artificial heart (TAH) is the sole remaining option for patients with biventricular failure who cannot be rescued by left ventricular assist devices (LVADs) alone. However, the pulsatile TAH in clinical use today has limitations: large pump size, unknown durability, required complex anticoagulation regimen, and association with significant postsurgical complications. That pump is noisy; its large pneumatic driving lines traverse the body, with bulky external components for its drivers. Continuous-flow pumps, which caused a paradigm shift in the LVAD field, have already contributed to the rapidly evolving development of TAHs. Novel continuous-flow TAHs are only in preclinical testing or developmental stages. We here review the current state of TAHs, with recommended requirements for the TAH of the future.

Implantation technique of the 50-cm3 SynCardia Total Artificial Heart: does size make a difference?

Despite downsizing, implantation technique of the 50-cm(3) SynCardia Total Artificial Heart and settings of the Companion driver remain unchanged. Owing to the absence of de-airing nipples, de-airing procedure is even more crucial and has to be performed carefully.

Primary side control of load voltage for transcutaneous energy transmission

Transcutaneous energy transmission (TET) is considered as a good way to wirelessly power the implanted devices in human bodies. The load voltage provided from the TET to the implanted device should be kept stable to ensure the device working well, which however, is easily affected by the required power variation for different body movements and coil-couple malposition accompanying skin peristalsis. Commonly, the load voltage applied onto the device should be measured and feedback for power is regulated by implanting sensing and communication units into the body, which causes additional energy cost, increased size and weight of the implanted device. This paper takes the TET for artificial heart as an example to propose a novel primary side control method of the load voltage for TET, which does not require any additional implanted components. In the method, sensing coils are used to measure the malposition between the transmitter coil (TC) and receiver coil, and the magnitude of the TC current outside the human body. The measurement results are used to estimate the load voltage inside the body through calculation, whose value provide a base to develop a PI control system to regulate the input power of TET for the load voltage stability. The proposed method is experimentally validated on an actual TET for artificial heart by varying its load in a wide range under serious coil-couple malposition. With applying the primary side control, the variation of the load voltage is reduced to only 25 % of that without the control.

Percutaneous dilatational tracheostomy following total artificial heart implantation

Coagulation disorders and an immune-altered state are common among total artificial heart patients. In this context, we sought to evaluate the safety of percutaneous dilatational tracheostomy in cases of prolonged need for mechanical ventilatory support. We retrospectively analysed the charts of 11 total artificial heart patients who received percutaneous dilatational tracheostomy. We focused on early and late complications. We observed no major complications and no procedure-related deaths. Early minor complications included venous oozing (45.4%) and one case of local infection. Late complications, including subglottic stenosis, stomal infection or infections of the lower respiratory tract, were not observed. In conclusion, percutaneous dilatational tracheostomy in total artificial heart patients is safe. Considering the well-known benefits of early tracheotomy over prolonged translaryngeal intubation, we advocate early timing of therapy in cases of prolonged mechanical ventilation.

Optimal design of the hydrodynamic multi-arc bearing in a centrifugal blood pump for the improvement of bearing stiffness and hemolysis level

The purpose of the present study is to establish an optimal design of the multi-arc hydrodynamic bearing in a centrifugal blood pump for the improvement of bearing stiffness and hemolysis level. The multi-arc bearing was designed to fulfill the required specifications: (i) ensuring the uniform bearing stiffness for various bearing angles; (ii) ensuring a higher bearing stiffness than the centrifugal force to prevent impeller whirl; and (iii) adjusting the bearing clearance as much as possible to reduce hemolysis. First, a numerical analysis was performed to optimize three design parameters of the multi-arc bearing: number of arcs N, bearing clearance C, and groove depth H. To validate the accuracy of the numerical analysis, the impeller trajectories for six pump models were measured. Finally, an in vitro hemolysis test was conducted to evaluate the hemolytic property of the multi-arc bearing. As a result of the numerical analysis, the optimal parameter combination was determined as follows: N=4, C=100 μm, and H ≥ 100 μm. In the measurements of the impeller trajectory, the optimal parameter combination was found to be as follows: N=4, C=90 μm, and H=100 μm. This result demonstrated the high reliability of the numerical analysis. In the hemolysis test, the parameter combination that achieved the smallest hemolysis was obtained as follows: N=4, C=90 μm, and H=100 μm. In conclusion, the multi-arc bearing could be optimized for the improvement of bearing stiffness and hemolysis level.