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Medical Biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
It was the advent of cyclosporine that altered transplants from research surgery to life-saving treatment. In 1968, surgical pioneer Denton Cooley performed 17 transplants, including the first heart–lung transplant. Fourteen of his patients were dead within 6 months. By 1984, two-thirds of all heart transplant patients survived for 5 years or more. With organ transplants becoming commonplace, limited only by donors, surgeons moved onto more risky fields—multiple organ transplants on humans and whole-body transplant research on animals. On March 9, 1981, the first successful heart–lung transplant took place at Stanford University Hospital. The head surgeon, Bruce Reitz, credited the patient’s recovery to cyclosporine A. In most countries, there is a shortage of suitable organs for transplantation. Countries often have formal systems in place to manage the allocation and reduce the risk of rejection. Some countries are associated with international organizations like Eurotransplant to increase the supply of appropriate donor organs and allocate organs to recipients. Transplantation also raises several bioethical issues, including the definition of death, when and how consent should be given for an organ to be transplanted, and payment for organs for transplantation.
Medical biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
It was the advent of cyclosporine that altered transplants from research surgery to life-saving treatment. In 1968, surgical pioneer Denton Cooley performed 17 transplants, including the first heart–lung transplant. Fourteen of his patients were dead within 6 months. By 1984, two-thirds of all heart transplant patients survived for 5 years or more. With organ transplants becoming commonplace, limited only by donors, surgeons moved onto more risky fields—multiple organ transplants on humans and whole-body transplant research on animals. On March 9, 1981, the first successful heart–lung transplant took place at Stanford University Hospital. The head surgeon, Bruce Reitz, credited the patient’s recovery to cyclosporine-A. As the rising success rate of transplants and modern immunosuppressants make transplants more common, the need for more organs has become critical. Advances in living related-donor transplants have made that increasingly common Additionally, there is substantive research into xenotransplantation or transgenic organs. Although these forms of transplant are not yet being used in humans, clinical trials involving the use of specific cell types, such as using porcine islets of Langerhans to treat type 1 diabetes, have been conducted with promising results. However, there are still many problems that need to be solved before these would be feasible options in patients requiring transplants.
Medical Applications of Ultrasonic Energy
Published in Dale Ensminger, Leonard J. Bond, Ultrasonics, 2011
Dale Ensminger, Leonard J. Bond
Ultrasonic diagnostic procedures have generated considerable interest and application in the study of cardiac functions. Major causes of death following heart transplants have been acute rejection and infection. A-scan techniques have been used at the Stanford University Medical Center [106] in an effort to detect early signs of rejection. When rejection is indicated, dosages of immunosuppressive agents are lowered and active therapy of the rejection is begun. The method consists of measuring the dimensions of the heart as it fills with fluid. As the heart fills at the onset of rejection, the muscle walls swell and stiffen. Measurements are made using a 19.0-mm-diameter, 2.25-MHz transducer at a pulse repetition rate of 1000/s. Echo indications from the anterior wall and the posterior-wall surfaces provide the measurement information, with the distance from the anterior wall to the posterior wall indicating the overall heart size.
Mechanical circulatory support device selection for bridging to cardiac transplantation: a clinical guide
Published in Expert Review of Medical Devices, 2023
Tamari Miller, Veli K. Topkara
Right ventricular support devices may be necessary for isolated right ventricular failure or biventricular failure. Impella RP (Abiomed Inc, Danvers, MA) is a percutaneous axial flow device inserted through the femoral artery that proves up to 4 L/min of flow to support the RV. Its hemodynamic consequences include increased cardiac output, decreased right atrial pressure, but increased mean PA and pulmonary capillary wedge pressures. Data supporting the use of Impella RP is limited but suggests a 70% 30-day survival in small studies [43,44]. Impella RP® may be combined with Impella CP® or Impella 5.5® to provide biventricular support. Its use as a bridging device for heart transplant has not been adequately studied. TandemHeart® RVAD is an extracorporeal centrifugal flow pump that uses femoral or internal jugular vein access with an inflow cannula in right atrium pumping blood to the outflow cannula in the main pulmonary artery providing up to 4 L/min of support. Protek Duo uses a dual-lumen cannula in the internal jugular configuration with inflow in the right atrium and outflow in the main pulmonary artery providing similar support to the TandemHeart® RVAD. Both Tandem RVAD and Protek Duo can be connected to an oxygenator to improve systemic oxygenation in a configuration referred to as Oxy-RVAD. While these options exist for isolated right ventricular support, often pre-transplant patients require biventricular support and VA-ECMO is most frequently used to provide this support. Still, there is a paucity of data to support their use in bridging to heart transplant.
Overset meshing in combination with novel blended weak-strong fluid-structure interactions for simulations of a translating valve in series with a second valve
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
J. Bornoff, H.S. Gill, A. Najar, I.L. Perkins, A.N. Cookson, K.H. Fraser
Heart failure (HF) currently affects 64.35 million patients worldwide (Lippi and Sanchis-Gomar 2020). Treatments for HF range from healthy lifestyle changes and medication to heart transplant surgery, which is considered the gold standard in treating end-stage HF. However, the number of available donors is limited. Since 2011, the number of patients on the heart transplant waiting list in the UK has increased by 85%, but there are only half the number of donors available (NHS BaT 2021). To alleviate the shortfall, doctors can turn to mechanical circulatory support devices to bridge the gap to transplant. These devices include ventricular assist devices, used in cases of ventricular failure to partially assist in cardiac function, and total artificial hearts (TAHs), which fully replace the native heart in cases of biventricular HF.
Device profile of the Impella 5.0 and 5.5 system for mechanical circulatory support for patients with cardiogenic shock: overview of its safety and efficacy
Published in Expert Review of Medical Devices, 2022
Mohit Pahuja, Jaime Hernandez-Montfort, Evan H. Whitehead, Masashi Kawabori, Navin K. Kapur
For patients whose hemodynamics and cardiac index remains stable, slow weaning of the Impella device can be initiated by decreasing the P-level in 2-level steps [for example: P-6 to P-4 to P-2]. Continue to monitor hemodynamics and cardiac index closely as the P-levels are decreased. When P-2 level is reached, maintain the patient on this support until hemodynamics remain stable. Then the Impella catheter can be decreased further to P-1 level and pulled into the aorta either in the catheterization lab or the operating room under fluoroscopy or echocardiogram. The Impella device can then be decreased to P-0 before explantation. Vascular closure is performed after the removal. Impella 5.0 and 5.5 require surgical exposure, and after the device removal appropriate graft explantation is optional based on the surgeon’s preference, the vascular graft can be shortened and buried under the pectoralis muscles (the vascular graft explantation with a vessel reconstruction is indicated in case of infection), and vascular closure are required. In cases where weaning is unsuccessful, patients can be considered for bridge to advanced heart failure therapies such as LVAD and heart transplant.