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Recent Innovative Technologies in Heart and Lung Transplantation

Anitha Chandrasekhar, Clinical Lead- Lung Bioengineering and Organ Procurement, Northwestern Medicine

Transplantation is a highly specialized area of medicine and often the only treatment option to improve the quality of life for individuals with serious and complex terminal organ failure. It is an ever-evolving field and the technological advancements made in the field of heart and lung transplantation have been phenomenal over the last 50 years. Artificial intelligence and machine learning are increasingly being used to assist clinicians in decision-making for the care of these high-risk transplant patients. This field is tantalizingly poised to enter a new era of smart science applications where sensational expert systems and staggering expert minds would co-create the patient management strategy.

1. Can you provide an overview of the most significant technological advancements in heart and lung transplantation over the past decade?

During the past decade, transplantation has undergone significant developments, including the expansion of donor criteria, changes in allocation systems, and implementation of novel therapeutic interventions, leading to broader indications and improved long-term survival. There has been a mammoth evolution of every aspect of transplantation including surgical techniques, mechanical circulatory support, organ preservation and perfusion, organ transport devices, immunosuppression, personalized medicine via pharmacogenomics, non-invasive biomarkers, use of artificial intelligence in prognosticating outcomes, monitoring of allograft function and rejection surveillance. The use of extended criteria donors, donation after circulatory death (DCD), and assessment and optimization of previously unsuitable donor hearts and lungs using ex vivo perfusion have revolutionized thoracic organ transplantation.

2. Organ preservation and perfusion technologies have seen substantial advancements. Could you explain the latest techniques and their impact on transplant success rates?

The heart and lung perfusion systems offer extended preservation of the respective organs and have reshaped the transplantation domain. The heart perfusion system helps shorten the heart waitlist by increasing the donor pool and translates to better outcomes and fewer patient deaths while awaiting a heart.     

Recently, there has been a substantial increase in the number of heart transplants due to machine-perfused hearts. These were more commonly allocated to lower urgency status patients, indicating improved access to transplantation with the Organ Care System.  Similarly, EVLP technology has led to an increase in transplantation numbers, with comparable allograft survival and no significant difference in chronic lung allograft dysfunction compared to standard donors.

3. What are the key developments in mechanical circulatory support devices for transplant patients, and how have they improved patient outcomes?

Mechanical circulatory support (MCS) devices are innovative treatment options designed to re-establish systemic perfusion and support heart/ lung in terminal organ failure patients. MCS can be used as a bridge to transplant, bridge to decision, bridge to recovery, or in some cases as destination therapy. They can be broadly classified into short-term support devices such as Intra-aortic Balloon Pump (IABP), Extra-corporeal Membrane Oxygenation (ECMO), and Impella or long-term support devices such as Ventricular Assist Device (VAD) or Total Artificial Heart (TAH). These devices are proven to improve survival to hospital discharge in end-stage heart failure patients. Their use has expanded beyond short-term prophylactic support to include procedures in the catheterization laboratory, electrophysiology suite, operating room, and intensive care unit. As the waiting time for heart transplantation has increased, ventricular assist devices have become critical for “bridging” patients with end-stage heart failure. In recent times, increased use of biventricular assist devices has led to the survival of the sickest of patients, and the outcomes have been compelling.

4. The use of AI and machine learning in transplant medicine has been mentioned. Can you elaborate on how these technologies are being utilized in prognosticating outcomes and decision-making for transplant patients?

Artificial intelligence (AI) and machine learning (ML) can enhance a patient's transplantation journey by predicting the potential benefits of transplantation based on initial lab investigations and imaging. They also help identify potential graft failure and mortality after transplantation, assist patients with medication adherence, and encourage positive behavioral changes to minimize further cardiovascular risk. The use of ML models in cardiac transplantation has allowed clinicians to explore a greater number of variables, including those that were previously thought to be of limited use. By analyzing these variables, clinicians can accurately predict the prognosis of patients after transplantation, quantify the risk of rejection, and estimate waitlist mortality for those who may not survive long enough to receive an organ.

5. Personalized medicine through pharmacogenomics is becoming increasingly important in transplantation. How is genetic information used to tailor immunosuppressive treatments for individual patients?

Pharmacogenomics is the practice of creating personalized pharmacological therapy with the highest therapeutic index, based on an individual's genomic composition. In transplantation, pharmacogenomics allows immunosuppressive drug therapy to be specifically tailored to each patient. By matching the drug to the individual's genomic makeup, clinicians can choose the best immunosuppressive drug for any given clinical condition, thereby reducing morbidity and prolonging survival.

The idea behind "personalized medicine" is that each patient is unique and should receive treatment that is tailored to their specific needs, based on factors such as their medical history, metabolism, genetic background, and epigenetic factors. The ultimate goal of precision medicine for immunosuppression in transplantation is to optimize drug effectiveness and minimize negative side effects for each patient. This means avoiding overdosing that can lead to serious problems like infections, organ toxicity, or nephrotoxicity, as well as underdosing which can result in graft rejection.

6. Non-invasive biomarkers have gained attention in monitoring allograft function and rejection surveillance. Could you discuss the latest advancements in this area and their clinical applications?

There is an increased use of non-invasive biomarkers to predict rejection due to the limitations of endomyocardial biopsy. The allograft injury is characterized by two biomarkers. Troponin and donor-derived cell-free DNA (dd-cfDNA). Additionally, two circulating biomarkers, AlloMap, and microRNA (miRNA), reflect the inflammatory and alloimmune processes associated with allograft rejection. Out of these, the two most promising non-invasive alternatives that are in clinical use in North America include assessment of peripheral gene expression profiling and dd-cfDNA. Gene-expression profiling (AlloMap assay) involves the quantification of 11 genes in peripheral blood mononuclear cells that are involved in various pathways such as lymphocyte activation, cell migration, T-cell priming, hematopoietic proliferation, steroid sensitivity, and platelet activation. There is a significant and growing body of literature that supports the use of dd-cfDNA as a reliable marker of cardiac allograft injury. Not only is there a clear biological rationale for this, but the test is also highly reproducible, with well-known kinetics following transplantation, and has been linked to allograft rejection in both case-control studies and multicenter cross-sectional studies.

7. Organ transport devices play a critical role in transplantation. What innovations have been introduced to enhance organ transportation safety and efficiency?

Rapid advances in organ preservation and transport technologies make it possible for organs to travel further to reach the sickest patients in need of a transplant. The transport system can monitor the heart's hemodynamic parameters every 15 to 30 minutes as if it were a patient in the ICU. The advantages of transport devices are that they allow a heart to travel distances up to 1,000 miles or six hours and enable the use of hearts from older donors and those that would have been rejected.

During organ transport, various parameters are closely monitored to ensure the organ's viability such as oxygen levels, temperature, pH, perfusion pressure, and organ function. Perfusion systems provide optimized preservation conditions and extended preservation time, allowing for greater flexibility in logistics.

8. How do you envision the future of heart and lung transplantation in terms of smart science applications and expert systems collaborating in patient management strategies?

Medical decision support systems have become increasingly important in healthcare in recent years. Expert systems have three main applications in the treatment and management of heart failure patients namely classification of various stages of heart disease, early detection, and patient surveillance after heart transplantation. AI is employed effectively in chronic care management, which is paramount in dictating the outcome and quality of life of high-risk patients undergoing heart and lung transplantation. Clinical applications include the detection of acute cellular rejection in heart and lung biopsies, prediction of post-heart transplant graft function, re-transplantation, graft survival, cardiac allograft vasculopathy, and assessment of blood levels of immunosuppressive medications. Digital therapeutics is another smart science application wherein a ‘virtual doctor’ with an interactive physician avatar interface is being created for self-care at home to guide the safe prescribing of medications and management of co-morbidities in heart failure patients.

9. Are there any ethical or regulatory challenges associated with the integration of advanced technologies in heart and lung transplantation, and how are they being addressed?

The development and implementation of AI and Bio-printed organs raise important regulatory and ethical considerations. AI has the potential to exacerbate existing inequalities if not appropriately designed and implemented. It is crucial to ensure that AI systems used in healthcare are accurate and reliable. When AI is used for diagnosis or treatment without robust validation, ethical concerns arise as errors can result in incorrect medical decisions. A distinct challenge in the field of AI ethics is the need for constant monitoring, review, and auditability to ensure that the systems perform impartially and reliably.

Regulatory bodies are being formed to establish guidelines and standards to ensure the safety, efficacy, and quality of these innovations for clinical use. Effective governance of organ procurement and bio-printing requires legal frameworks and regulations. Achieving a balance between innovation, patient safety, and ethical concerns is crucial for the responsible advancement and adoption of these technologies in transplantation.

10. Can you provide examples of successful cases or outcomes where these innovative technologies have made a significant difference in the lives of transplant patients?

The EXPAND trial, which is a prospective, multi-center trial to evaluate the effectiveness of the Organ Care System, assessed high-risk transplants with prolonged ischemic times (>4 hours) or marginal donor heart features such as left ventricular hypertrophy, an ejection fraction of 40-50%, donor downtime >20 minutes, and donor age >55 years, and found excellent short-term outcomes. Ex vivo heart perfusion can thus expand the donor pool by using hearts that are otherwise considered unsuitable for transplantation.

Clinical trials have conclusively demonstrated that Ex-Vivo Lung Perfusion (EVLP) is a reliable and beneficial technology. The INSPIRE trial conducted for TransMedics OCS recruited standard donor lungs for bilateral lung transplant and showed a 50% lower cumulative incidence of primary graft dysfunction. The HELP trial, which evaluated the XVIVO system, showed a 15% incidence of primary graft dysfunction at 72 hours, compared to 30% in the non-EVLP group, with no significant difference in survival. The NOVEL trial studied EVLP for extended criteria donors and revealed that 50.9% of initially unsuitable grafts were successfully transplanted.

11. What ongoing research and development efforts are taking place in the field of heart and lung transplantation technology, and what breakthroughs can we anticipate in the near future?

Presently, the major hurdles in transplantation are devising personalized approaches, which can potentially eliminate the need for lifelong immunosuppression, and expand the pool of donors feasible for human transplantation. Three emerging technologies tackle these challenges. Single-cell RNA sequencing technology is evolving rapidly and has revealed new molecular signatures involved in alloimmune responses. Sophisticated nanotechnology platforms enable the delivery of immune-modulating agents that can precisely target the host immune response, leading to donor-specific tolerance. CRISPR/Cas9 gene editing technology has the potential to remove immunogenic molecules while inserting desirable regulatory ones with great precision. This technology can generate genetically modified pigs for xenotransplantation, which can solve the issue of the shortage of human organs.

Another futuristic ground-breaking innovation in the field of organ transplantation is bioprinting. Bioprinting involves creating three-dimensional structures using living cells, which can be used to generate functional organs and eliminate the shortage of donor organs. By using a patient's cells, organs can be created in the lab, making transplants more readily available and reducing the risk of rejection.

12. How do you see the collaboration between healthcare professionals, engineers, and data scientists evolving to further advance the field of heart and lung transplantation?

With AI assuming a pivotal role in the coming years in heart and lung transplantation, the importance of collaborations between clinicians, system experts and data scientists cannot be overstated. Partnerships allow for the exchange of expertise, resources, and technologies. Engineers bring real-world applications, commercialization capabilities, and funding, while healthcare professionals contribute clinical knowledge, specialized facilities, and research capabilities. Data scientists develop algorithms to learn patterns from clinical data to generate predictive models using AI. These collaborations foster the translation of clinical research into practical solutions, accelerating the development of innovative technologies and their applications.

13. Are there any specific challenges or limitations that you foresee in the continued adoption of these technologies in heart and lung transplantation?

The key challenges of incorporating AI into transplant include obtaining relevant data with good quality, incorporating algorithms into decision-making processes, and identifying criteria for adoption. Collaboration among organizations, cross-functional teams, and international partnerships are crucial for driving innovation in organ care technology. Such partnerships help in sharing knowledge, resources, and expertise, leading to the development of effective regulatory frameworks and responsible innovation practices. It can help overcome challenges, improve outcomes, address organ shortages, and transform healthcare.

14. Could you share insights into the cost-effectiveness and accessibility of these advanced technologies for patients in need of heart and lung transplants?

AI techniques can reduce inaccuracies in data, resulting in reliable outcomes and reduced expenses associated with errors. It can be cost-effective as hospitals can reduce the time and resources spent on manual processes by automating repetitive tasks and freeing employees to focus on more strategic objectives. Automation also helps minimize errors and increase consistency, leading to improved decision-making and better patient experiences. It has been estimated that the implementation of AI across healthcare could result in savings of around $200 billion to $360 billion per year, equivalent to a 5-10% reduction in healthcare spending.

15. Finally, what advice or recommendations do you have for healthcare institutions and practitioners looking to incorporate these innovations into their transplantation programs effectively?

For implementing any new technology into clinical practice, it is imperative to have thorough training, structured protocols, robust validation, and regulatory checks to avoid causing harm to patients and to effectively advance the standard of care. Maintaining safe, reliable systems and infrastructure, enhancing oversight and increasing transparency of the peer-review process can help effective implementation of newer technology into clinical practice.

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Author Bio

Anitha Chandrasekhar

Dr. Anitha Chandrasekhar is a Cardiothoracic surgical professional with over 2 decades of involvement in cardiac surgeries including the entire spectrum of congenital, coronary, valvular, aortic, heart and lung transplantation, and ventricular assist device implantation procedures. She has presented scientific papers extensively in national and international surgical conferences and published articles in indexed journals. She has held leadership positions in various associations and carved a unique pathway in the cardiac surgical domain. As a passionate ‘Surgical Scientist’, she is currently serving a hybrid surgical plus research role as a Clinical Lead- Lung Bioengineering and Organ Procurement at Northwestern Medicine, Chicago, IL, USA.

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