Personer med hjärtsvikt överlever idag längre än tidigare och allt fler utvecklar grav hjärtsvikt. Mekaniska hjälphjärtan kan bli ett alternativ för personer med långt framskriden hjärtsvikt. Insättning av mekaniska hjälphjärtan ger positiva effekter i form av minskad symtombörda, bättre fysisk funktion samt ökad livslängd. Insättningen av ett mekaniskt hjälphjärta kan dock påverka livskvaliteten negativt. Identifiering av upplevelser som påverkar livskvaliteten hos personer med ett mekaniskt hjälphjärta är av vikt för att kartlägga relevanta omvårdnadsåtgärder. Syftet med studien var att belysa upplevelser av livskvalitet hos personer med hjärtsvikt i samband med behandling av ett mekaniskt hjälphjärta. En allmän litteraturstudie med induktiv ansats genomfördes och resultatet baserades på nio resultatartiklar. Resultatet visade att personers livslängd ökade liksom deras fysiska funktion. Dock påverkas livskvaliteten negativt av restriktioner och känslor som påverkar synen på sig själv. Personerna upplevde känslor som minskad autonomi, förlorad identitet, förlorad kontroll och känslor av att vara bunden i vardagen. Psykiskt och praktiskt stöd ansågs som viktigt. Personer upplevde även brist på information i beslutsfattandeprocessen och innan utskrivning. Med ståndpunkt i denna studiens resultat kan personer med mekaniska hjälphjärtan gagna från mer information och patientutbildning samt erbjudas psykologiskt-, socialt- och praktiskt stöd. / People with heart failure are now surviving longer than before and several people develop severe heart failure. Ventricular assist devices can be an option for people with advanced heart failure. Implantation of a ventricular assist device has positive effects in the form of reduced symptom burden, improved physical function and increased life expectancy. However, life with a ventricular assist device can adversely affect the quality of life. Identifying experiences that affect the quality of life of people with a ventricular assist device is important to identify relevant nursing interventions. The purpose of this study was to illustrate experiences of quality of life in people with heart failure in correlation with the treatment of a ventricular assist device. A general literature study with an inductive approach was conducted and the results were based on nine resultarticles. Results showed that people’s life expectancy increased as did their physical function. However, the quality of life is negatively affected by restrictions and emotions that affect the view of oneself. Individuals experienced feelings such as reduced autonomy, lost identity, lost control and feelings of being bound in everyday life. Psychological and practical support was considered important. People also experienced a lack of information in the decision-making process and before discharge. Based on the results of this study, people with ventricular assist devices can benefit from more information and patient education and also be offered psychological-, social- and practical support.

No description available.

A left ventricular assist device is a mechanical pump implanted in patients with heart failure that continuously takes blood from the left ventricle and delivers it to the aorta, thus decreasing ventricular load. The device is typically considered as a ‘bridge to transplant’, i.e. as a temporary therapy, and involves several risks. Modified ventricular hemodynamics due to a heart pump implantation is studied in-vitro using an elastic ventricle. The ventricle is incorporated into a pulse duplicator setup, which prescribes realistic pulsatile inflow/outflow to mimic a weak ejection fraction. A continuous axial pump mimics a ventricular assist device and its effect on the ventricular hemodynamics is investigated as a function of the pump flow suction. Using particle image velocimetry, pump flow effectiveness at providing unloading on the ventricle and increasing ejection is observed and understanding if proper recirculation of the myocardium down to the apex is restored under varying flow rate.

The Left Ventricular Assist Device (LVAD) is a rotary mechanical pump that is implanted in patients with congestive heart failure to help the left ventricle in pumping blood in the circulatory system. The rotary type pumps are controlled by varying the pump motor current to adjust the amount of blood flowing through the LVAD. One important challenge in using such a device is the desire to provide the patient with as close to a normal lifestyle as possible until a donor heart becomes available. The development of an appropriate feedback controller that is capable of automatically adjusting the pump current is therefore a crucial step in meeting this challenge. In addition to being able to adapt to changes in the patient's daily activities, the controller must be able to prevent the occurrence of excessive pumping of blood from the left ventricle (a phenomenon known as ventricular suction) that may cause collapse of the left ventricle and damage to the heart muscle and tissues. In this dissertation, we present a new suction detection system that can precisely classify pump flow patterns, based on a Lagrangian Support Vector Machine (LSVM) model that combines six suction indices extracted from the pump flow signal to make a decision about whether the pump is not in suction, approaching suction, or in suction. The proposed method has been tested using in vivo experimental data based on two different LVAD pumps. The results show that the system can produce superior performance in terms of classification accuracy, stability, learning speed, iv and good robustness compared to three other existing suction detection methods and the original SVM-based algorithm. The ability of the proposed algorithm to detect suction provides a reliable platform for the development of a feedback control system to control the current of the pump (input variable) while at the same time ensuring that suction is avoided. Based on the proposed suction detector, a new control system for the rotary LVAD was developed to automatically regulate the pump current of the device to avoid ventricular suction. The control system consists of an LSVM suction detector and a feedback controller. The LSVM suction detector is activated first so as to correctly classify the pump status as No Suction (NS) or Suction (S). When the detection is “No Suction”, the feedback controller is activated so as to automatically adjust the pump current in order that the blood flow requirements of the patient’s body at different physiological states are met according to the patient’s activity level. When the detection is “Suction”, the pump current is immediately decreased in order to drive the pump back to a normal No Suction operating condition. The performance of the control system was tested in simulations over a wide range of physiological conditions.

The aim of this retrospective study was to investigate whether there would be an association between periodontal disease parameters and positive bacterial findings at the driveline of patients with a left ventricular assist device (LVAD). Patients with an LVAD, who underwent a full oral and microbiological examination between 2016 and 2018, were included. During oral examination, periodontitis severity (stage and grade) and the periodontal inflamed surface area (PISA) were evaluated. A microbiological analysis was performed from swabs of the driveline, whereby different bacterial species were cultivated and analyzed. A total of 73 patients were included in the current study. The majority of participants (80.8%) had at least one positive bacterial finding during the study period. Most patients had a periodontitis stage of III-IV (80.9%). The determined PISA of the total group was 284.78 ± 352.29 mm2. No associations were found between the periodontal disease parameters and the bacterial findings in general, the bacterial findings on the day of oral examination or the bacterial findings 12 months prior to/after the oral examination (p > 0.05). Periodontitis is not associated with cultivated microbiological findings at the driveline of patients with an LVAD and thus appears not to be a risk indicator for driveline colonization. Nevertheless, the high periodontal burden in LVAD patients underlines the need for their improved periodontal care.

The rotary Left Ventricular Assist Device (LVAD) is a mechanical pump surgically implanted in patients with end-stage congestive heart failure to help maintain the flow of blood from the sick heart. The rotary type pumps are controlled by varying the impeller speed to control the amount of blood flowing through the LVAD. One important challenge in using these devices is to prevent the occurrence of excessive pumping of blood from the left ventricle (known as suction) that may cause it to collapse due to the high pump speed. The development of a proper feedback controller for the pump speed is therefore crucial to meet this challenge. In this thesis, some theoretical and practical issues related to the development of such a controller are discussed. First, a basic nonlinear, time-varying cardiovascular-LVAD circuit model that will be used to develop the controller is reviewed. Using this model, a suction index is tested to detect suction. Finally we propose a feedback controller that uses the pump flow signal to regulate the pump speed based on the suction index and an associated threshold. The objective of this controller is to continuously update the pump speed to adapt to the physiological changes of the patient while at the same time avoiding suction. Simulation results are presented under different conditions of the patient activities. Robustness of the controller to measurement noise is also discussed.

No description available.

No description available.

<p>Respiratory distress syndrome is a major cause of mortality among pre-term and term neonatal population. To overcome the limitations of current therapies, a new form of respiratory support termed the, “Artificial Placenta” has been proposed. The Artificial Placenta is a type of oxygenator that is attached postnatally via the umbilical vessels to provide pumpless respiratory support to pre-term and term neonates. To develop this concept, our group previously reported on a novel polycarbonate membrane lung assist device (LAD). To build upon its development, the objectives of this thesis are to determine the optimal interface for gas exchange, and characterize the gas exchange properties of the LAD under ambient and oxygen rich atmosphere. Subsequently, its feasibility was determined by studying the effects of extracorporeal flow rates on cardiovascular parameters and gas exchange performance was assessed in a newborn piglet model.</p> <p>In vitro testing demonstrated that PDMS based membrane is the optimal interface for gas exchange in the LAD. In vitro testing of the LAD demonstrated 2.4 µL/min/cm² -3.8 µL/min/cm² and 6.4 µL/min/cm²- 10.1 µL/min/cm² of O₂ and CO₂ transfer respectively under ambient air and oxygen rich atmospheric conditions. Based on these results, the LAD theoretically could provide 6-11% of metabolic O₂ while eliminating 18-26% of CO₂in a newborn healthy pre term infant. Experiments in newborn piglet models achieved pumpless configuration with flow rates up to 60.9ml/kg/min without presenting decompensation. Preliminary, in vivo gas exchange experiments demonstrated O₂ transfer of 3ul/min/cm², which matches closely to in vitro data.</p> <p>A novel pumpless LAD is reported, which provides sufficient respiratory support. High extracorporeal flow rates with stable cardiovascular parameters demonstrate feasibility of the artificial placenta concept. This novel LAD could potentially serve as a rescue device when all other therapies such as nasal continuous positive airway and mechanical ventilation fail.</p> / Master of Applied Science (MASc)

Various congenital heart defects (CHDs) are characterized by the existence of a single functional ventricle, which perfuses both the systemic and pulmonary circulation in parallel. A three-stage palliation procedure, including the final Fontan Completion, is often adopted by surgeons to treat patients with such CHDs. However, the most common outcome of this surgery, an extra-cardiac total cavopulmonary connection (TCPC), formed by suturing the inferior vena cava (IVC) and superior vena cava (SVC) to the pulmonary arteries (PAs), results in non-physiological flow conditions, systemic venous hypertension, reduced cardiac output, and pressure losses, which ultimately calls for a heart transplantation. A modest pressure rise of 5-6 mm Hg would correct the abnormal flow dynamics in these patients. To achieve this, a novel conceptual design of a percutaneous dual propeller pump inserted and mounted inside the TCPC is developed and studied. The designed blood pump is percutaneously inserted via the Femoral vein and deployed at the center of Total Cavopulmonary Connection (TCPC). The two propellers, each placed in the Superior Vena Cava (SVC) and the Inferior Vena Cava (IVC) are connected by a single shaft and motor, and thus rotate at same speed. The device is supported with the help of a self-expanding stent which would be anchored to the walls of the IVC and the SVC. An inverse design methodology implementing Blade Element Momentum theory and Goldstein's radial momentum loss theory was employed to generate the blade profiles for the studied propeller pumps. The propeller blade profiles generated from the inverse design optimization code were examined for hydraulic performance, blood flow pattern and potential for hemolysis inside the TCPC using 3-D computational fluid dynamics (CFD) analysis. The Lagrangian particle tracking approach in conjunction with a non-linear mathematical power law model was used for predicting the blood damage potential of the analysed blood pump designs by calculating the scalar shear stress history sustained by the red blood cells (RBC). The study demonstrated that the IVC and SVC propeller pumps could provide a pressure rise of 1-20 mm Hg at flow rates ranging from 0.5 to 5 lpm while rotating at speeds of 6,000-12,000 rpm. Moreover, the average Blood Damage Index (BDI), quantifying the level of blood trauma sustained by the RBCs for the analyzed propeller pump designs, was found to be around 3e-04% to 4e-04% which is within the acceptable limits for an axial flow heart assist device. Thus, such a dual propeller blood pump configuration could potentially provide assistance to Fontan patients by unloading the single functional ventricle thereby acting as a bridge to transplantation and recovery until a donor heart is available. / Master of Science