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Title: Experimental and computational investigations for the development of intro-aortic balloon pump therapy
Authors: Bruti, Gianpaolo
Advisors: Khir, A
Keywords: Left venricular assist device;Cardiovascular system;Counter pulsation;Coronary disease;Hemodynamics
Issue Date: 2016
Publisher: Brunel University London
Abstract: Heart failure (HF) is a widely prevalent state in developing countries, especially among people over 65, with percentages up to 10% of the population in the US. In all developed countries the expenditure related to congestive heart failure consists of a high percentage of the total health care expenditure, reaching 60% in the UK (1991 1). One of the main strategies for dealing with HF is the use of cardiac assist devices. Among these the most widely used device is the Intra-Aortic balloon pump (IABP). The IABP has as the main aims to increase coronary flow during inflation, and decrease end diastolic pressure and ventricular afterload during deflation. The device was introduced for the first time into clinical practice over 40 years ago, but open issues still remain with the performance of the device. In fact, both inflation and deflation effectiveness are compromised when the balloon operates at an angle to the horizontal, which is often the operating position of the device in intensive care units. The main aim of the work described in this thesis is to investigate the IABP in order to improve the efficacy of this therapy, in terms of IAB design and IABP timing effectiveness. For this purpose the balloon was first filmed in an experimental set-up to visualize its wall-motion with a high speed camera. The results of this investigation were the input for the development of different designs of balloon, tested at horizontal and angled positions. Both, inflation and deflation effectiveness were augmented using different shaped balloons in an experimental set-up characterized by static pressure as well as in one characterized by physiological pressure waveform. The improved performance was associated to an improved clinical outcome on a PV diagram. In addition different pumps and pump settings were studied in an experimental set-up, characterized by physiological aortic pressure waveform, in order to estimate the influence of different pump manufacturers and triggers on the performance of the device. In this case one of the pumps (Teleflex), with the new technology for pressure measurement via a fibre optic sensor, showed to best trigger the IAB after inflation onset, while the highest number of assisted beats was obtained when this pump was set on electrocardiogram (ECG) triggering. Nonetheless a first development of multi-dimensional computational model of the IAB counterpulsation was realized with the aim of establishing the effect of this therapy on relevant areas, such as aortic root, and in order to have an insight on the 3-D flow field in the surrounding of IAB: these information can be crucial for the optimisation of the balloon’s shape. In conclusion, the key finding was that a change in balloon shape influences both, inflation and deflation mechanics at horizontal and semi-recumbent positions, and this strategy can be used for maximising the IABP clinical benefits. With the aid of the computational model it will be possible to further develop the already tested balloon different shapes. Not less important, IABP therapy was demonstrated to be crucially influenced by the pump setting and mode (triggering inflation and deflation onsets), hence the clinical operator is addressed to change the pump mode of operation according to the patient’s condition to maximise the potential benefit of this therapy.
Description: This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London.
Appears in Collections:Mechanical and Aerospace Engineering
Dept of Mechanical Aerospace and Civil Engineering Theses

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