Objectives: Little is known about the performance of re - used pacemakers and implantable cardioverter defibrillators (ICDs) in Africa. We sought to compare the risk of infection and the rate of malfunction of re - used pacemakers and ICDs with new devices at Groote Schuur Hospital in Cape Town, South Africa. Methods: This was a retrospective case comparison study of performance of re - used pacemakers and ICDs in comparison with new devices at Groote Schuur hospital over a 10 year period. The outcomes were incidence of device infection, device malfunction, early battery depletion, and device removal due to infection, malfunction, or early battery depletion. Results: Data for 126 devices implanted in 126 patients between 2003 and 2013 were analysed, of which 102 (81%) were pacemakers (51 re - used and 51 new) and 24 (19%) were ICDs (12 re - used and 12 new). There was no device infection, malfunction, early battery depletion or device removal in either the re - used or new pacemaker groups ov er the median follow up of 15.1 months (interquartile range (IQR), 1.3 - 36.24 months) for re - used pacemakers and 55.8 months (IQR, 20.3 - 77.8 months) for new pacemakers. In the ICD group, no device infection occurred over a median follow up of 35.9 months (I QR, 17.0 - 70.9 months) for re - used ICDs and 45.7 months (IQR, 37.6 - 53.7 months) for new ICDs. One device delivered inappropriate shocks which resolved without intervention and no harm to the patient, this re - used ICD subsequently needed generator replacement 14 months later. In both, the pacemaker and ICD groups, there were no procedure non related infections documented for the respective follow up periods. Conclusion: No significant differences were found in performance between re - used and new pacemakers and ICDs with respect to infection rates, device malfunction, and battery life and device removal for complications. Pacemaker and ICD reusee is feasible and safe and is a viable option for patients with bradyarrhythmias and tachyarrthythmias.

Includes abstract. / Includes bibliographical references.

Bibliography: leaves 76-81.

Includes abstract. / Includes bibliographical references. / Aortic valve replacement in humans may be needed due to pathology leading to valve stenosis and regurgitation. Replacement is by either mechanical or soft tissue prosthetic valves. Before new valves are medically approved and introduced into the market they are required to undergo rigorous testing to verify performance and product life expectancy. Performance testing is done in a hydrodynamic test apparatus and life expectancy verified in an accelerated test apparatus. The Cardiology Department at Tygerberg Hospital has proposed a project for the design and implementation of a prosthetic aortic valve test apparatus. This device is to be used primarily for fatigue, but also limited hydrodynamic, testing of prosthetic heart valves. The design of the test apparatus was based on the four-element Windkessel model of the arterial system. This simple lumped parameter electrical analogy of the arterial system takes aortic and arterial resistance, arterial compliance, and blood inertance into account to simulate total arterial impedance. This model was developed with physiological reference and thus the element parameters only hold for physiological simulation as the equation governing impedance is speed sensitive. The model was adapted to provide theoretidal, physiological loads from physiological speeds of 60BPM through to accelerated speeds up to 1OOOBPM through mathematical optimisation of the Windkessel.The test apparatus was designed and built taking into account the varying Windkessel parameters where possible. Both compliance and resistance could be varied within an acceptable range, inertance however, could not be varied due to the limitations of the project. The apparatus was controlled and pressures on either side of the valve monitored with a LabView® graphical user interface. The apparatus was able to mimic in vivo closely and satisfied the ISO requirements for valve testing up to speeds of 230BPM. Various modifications are proposed to both the Windkessel model and the physical apparatus to compensate for hydrodynamic effects at high testing speeds in improve performance, as well as increase the maximum testing speed.

Includes bibliographical references.

Bibliography: leaves 91-98. / Patients with peripheral vascular disease (PVD) suffer from the symptom of intermittent claudication and are walking intolerant. However, it is not clear what contributes to walking intolerance in patients with PVD.

Includes abstract. Includes bibliographical references.

Bibliography: leaves 109-118. / Since there is a major scarcity of donor organs world-wide, the experimental search for human organs has focused on two alternatives; mechanical devices and cross-species transplants. The use of mechanical devices as substitute organs is understandably limited due to complications from trying to duplicate the function of complex organs such as the liver. This has resulted in a renewed interest in xenotransplantation. Organs from non-human primates would arguably be the organs of choice but ethical consideration prevents this. The transplantation of organs from pigs or sheep to humans i.e. xenotransplants, results in hyperacute rejection. The development of immunosuppressive agents such as Cyc1osporine A and Tacrolimus have significantly improved the survival of organ transplants. However, although there is a good 1-5 year survival, the recurrent problem of chronic rejection still remains, and unresponsiveness to allografts has never been induced by these immunosuppressive agents. More importantly, the presence of adverse side effects including immunological complications and drug toxicity e.g. nephrotoxicity, remains a serious problem. Since the drugs currently available for allotransplantation preferably target T -cells, and are therefore unlikely to be sufficient for xenotransplantation where there is a strong B-cell driven response, there is a need for new immunosuppressive agents. FTY720 (2 amino-2-(2-[ 4-octylphenyl] ethyl)-1,3-propanediol hydrochloride), a novel, immunosuppressive drug active in rodent and dog transplantation models, has shown no toxic side effects in pre-clinical studies although no long-term patient studies exist.

Includes bibliographical references (leaves 96-[100]). / The HIV/AIDS epidemic in South Africa is more severe than almost anywhere else in the world and continues to grow. Here, and elsewhere in southern Africa, it is now a generalized epidemic, largely heterosexually spread. This is very different from the more limited epidemic in the United States of America and other developed countries. It was in the USA in the five years after the first cases of AIDS that the understandings and explanations of HIV/AIDS were constructed. HIVIAIDS was defined as a transmittable infection causing a progressive deterioration of the immune system, leaving it vulnerable to opportunistic infections and disease of increasing severity resulting in inevitable death. Virology identified the virus that is the infectious agent and provided explanations of how it had its effect on the host, reproduced and was transmitted. Influenced by the early association of AIDS with homosexuals, the social construction of HIVIAIDS has focused on risk groups and risk behaviours. These are now central components of a dominant paradigm that has informed but also limited research. This paradigm also informs and limits responses to and strategies to prevent the spread of the virus.

Includes abstract. Includes bibliographical references.