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Browsing by Author "Howard, Brian"

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    Extending Function and Applications of Isolated Cardiopulmonary Systems
    (2016-11) Howard, Brian
    The use of isolated mammalian hearts has a history that is responsible for a staggering amount of the basic physiological knowledge we have about the cardiovascular system and is a primary gateway between ideas and clinical treatment. Advances in cardiac physiology, surgery, transplantation, pacing, defibrillation, ablation, and pharmacology are derived from this area of research. The work outlined here takes identified issues with experimental preparations, as well as clinical applications, to investigate solutions and directions for their systematic address. Extending the utility and window of viability of the isolated heart and lungs has resulted in clinically applicable advances in drug treatments and assessment tools. Most importantly though, it has the potential to expand the population of acceptable donor organs where there is immediate need and continuous shortfall in supply. My thesis consists of chapters which progress in translational application, making use of novel and comprehensive ways of controlling and investigating isolated cardiovascular systems. In the first chapter, the Visible Heart® preparation is used to replicate and extend a classic temperature experiment in the large isolated porcine heart. This chapter also addresses the clinical applications of optimizing heart function with emerging isolated heart transportation devices; making the best use of efforts to assess and maintain the heart for transplantation. This is followed in chapters 2 using the Visible Heart® system to assess therapeutic drug delivery for treating atrial fibrillation and again preserving a heart’s function for transplantation. The advancement of the isolated heart preparation is further driven by procedural concerns with cryo-ablation technologies to include functional lungs. This comprehensive system is used on actual human heart lung-bloc combinations for investigative purposes and required its own set of unique engineering solutions to produce a viable test platform. It is also this evolution of the isolated heart preparation that was a significant factor in bringing the Lung Organ Care System (OCS™) to the Visible Heart Laboratory as a unique research tool. As a commercial device, the OCS™ device seeks to replace the storage-on-ice standard of care with warm and ventilated perfusion of the lungs independent of the heart. As a laboratory instrument it has allowed new opportunities for investigating both basic lung physiology as well as providing lessons that are clinically applicable. The completely novel thermal monitoring of the lungs in this isolated state are discussed in Chapter 5 which investigates thermal tools and profiling of lung damage for the first time. This provides a whole new paradigm for emerging lung and general organ assessment directly relating identified injury states, overall lung function, and recovery/damage profiles that may help physicians make better use of precious donor lungs. In extending the use of the isolated lungs to an underutilized population of donors, the final chapter, Chapter 6, demonstrates for the first time a controlled study and injury model for donation after cardiac death (DCD). With modification to the current clinical use protocol for the OCS™ device, the viability window for injured lungs is shown to be nearly tripled. The impact of demonstrating viable DCD lungs on this system is the potential to greatly expand the number of lungs for transplantation, which would be invaluable to many currently on a long wait list. My thesis work has produced stable isolated cardio-vasculature systems with direct impact on the design of devices, investigation, therapy and monitoring in the pursuit of bettering the standard of care and expanding the availability of the organs for transplantation. It provides new and unique combinations of heart and lungs tailored to the investigative necessity in human anatomy and a more comprehensively described large mammalian model for anatomy, physiology and acute injury.