Heart-lung transplantation: current indications, prognosis and specific considerations

Optimization of photon counting CT for cardiac imaging in patients with left ventricular assist devices: An in-depth assessment of metal artifacts

PURPOSE

Photon counting CT (PCCT) holds promise for mitigating metal artifacts and can produce virtual mono-energetic images (VMI), while maintaining temporal resolution, making it a valuable tool for characterizing the heart. This study aimed to evaluate and optimize PCCT for cardiac imaging in patients during left ventricular assistance device (LVAD) therapy by conducting an in-depth objective assessment of metal artifacts and visual grading.

METHODS

Various scan and reconstruction settings were tested on a phantom and further evaluated on a patient acquisition to identify the optimal protocol settings. The phantom comprised an empty thoracic cavity, supplemented with heart and lungs from a cadaveric lamb. The heart was implanted with an LVAD (HeartMate 3) and iodine contrast. Scans were performed on a PCCT (NAEOTOM Alpha, Siemens Healthcare). Metal artifacts were assessed by three objective methods: Hounsfield units (HU)/SD measurements (DiffHU and SDARTIFACT), Fourier analysis (AmplitudeLowFreq), and depicted LVAD volume in the images (BloomVol). Radiologists graded metal artifacts and the diagnostic interpretability in the LVAD lumen, cardiac tissue, lung tissue, and spinal cord using a 5-point rating scale. Regression and correlation analysis were conducted to determine the assessment method most closely associated with acquisition and reconstruction parameters, as well as the objective method demonstrating the highest correlation with visual grading.

RESULTS

Due to blooming artifacts, the LVAD volume fluctuated between 27.0 and 92.7 cm3. This variance was primarily influenced by kVp, kernel, keV, and iMAR (R2 = 0.989). Radiologists favored pacemaker iMAR, 3 mm slice thickness, and T3D keV and kernel Bv56f for minimal metal artifacts in cardiac tissue assessment, and 110 keV and Qr40f for lung tissue interpretation. The model adequacy for DiffHU SDARTIFACT, AmplitueLowFreq, and BloomVol was 0.28, 0.76, 0.29, and 0.99 respectively for phantom data, and 0.95, 0.98, 1.00, and 0.99 for in-vivo data. For in-vivo data, the correlation between visual grading (VGSUM) and DiffHU SDARTIFACT, AmplitueLowFreq, and BloomVol was -0.16, -0.01, -0.48, and -0.40 respectively.

CONCLUSION

We found that optimal scan settings for LVAD imaging involved using 120 kVp and IQ level 80. Employing T3D with pacemaker iMAR, the sharpest allowed vascular kernel (Bv56f), and VMI at 110 keV with kernel Qr40 yields images suitable for cardiac imaging during LVAD-therapy. Volumetric measurements of the LVAD for determination of the extent of blooming artifacts was shown to be the best objective method to assess metal artifacts.

Four decades of progress in heart-lung transplantation: Two hundred seventy-one cases at a single institution

OBJECTIVE

The objective of this study is to evaluate survival for combined heart-lung transplant (HLTx) recipients across 4 decades at a single institution. We aim to summarize our contemporary practice based on more than 271 HLTx procedures over 40 years.

METHODS

Data were collected from a departmental database and the United Network for Organ Sharing. Recipients younger than age 18 years, those undergoing redo HLTx, or triple-organ system transplantation were excluded, leaving 271 patients for analysis. The pioneering era was defined by date of transplant between 1981 and 2000 (n = 155), and the modern era between 2001 and 2022 (n = 116). Survival analysis was performed using cardinality matching of populations based on donor and recipient age, donor and recipient sex, ischemic time, and sex matching.

RESULTS

Between 1981 and 2022, 271 HLTx were performed at a single institution. Recipients in the modern era were older (age 42 vs 34 y; P < .001) and had shorter waitlist times (78 vs 234 days; P < .001). Allografts from female donors were more common in the modern era (59% vs 39%; P = .002). In the matched survival analysis, 30-day survival (97% vs 84%; P = .005), 1-year survival (89% vs 77%; P = .041), and 10-year survival (53% vs 26%; P = .012) significantly improved in the modern era relative to the pioneering era, respectively.

CONCLUSIONS

Long-term survival in HLTx is achievable with institutional experience and may continue to improve in the coming decades. Advances in mechanical circulatory support, improved maintenance immunosuppression, and early recognition and management of acute complications such as primary graft dysfunction and acute rejection have dramatically improved the prognosis for recipients of HLTx in our contemporary institutional experience.

Prognosis factors in heart-lung transplantation: 30 years experience in a reference center

INTRODUCTION

Heart-lung transplantation has shown a progressive decrease in the number of procedures. There is a lack of information about this field in Spain. The main goal of this study is to analyze the experience of a national reference hospital.

METHODS

We performed a retrospective study of a historical cohort of heart-lung transplanted patients in a single center, during a 30 years period (from 1990 to 2021). The associations between variables were evaluated using the χ2 test or Fisher's exact test. Survival was analyzed using the Kaplan-Meier method. Differences were evaluated using the log-rank test and multivariate analysis with the Cox method.

RESULTS

A decrease in the number of procedures performed in the last decade was observed [2000-2009: 19 procedures (44.2%); 2010-2021: 15 procedures (34.8%)]. Early postoperative mortality was 23.3%, falling to 13.3% from 2010. In-hospital mortality was 41%, falling to 33% from 2010. Main factors related to higher mortality: previous thoracic surgery, corticosteroid therapy, extracorporeal circulation (ECLS) greater than 200 min, ischemia time greater than 300 min, and tracheal dehiscence (p < 0.005). Overall survival at one, five, and ten years was 58%, 44.7%, and 36.1%, respectively. Factors associated with lower survival rates: previous thoracic surgery, male donor, extracorporeal circulation greater than 200 min, ischemia time greater than 300 min, tracheal dehiscence and weight difference (p < 0.005).

CONCLUSIONS

There has been a progressive decrease in the number of heart-lung transplantations, being more evident in the last decade, but showing an improvement in both mortality and survival.

Lung Transplantation for Pulmonary Artery Hypertension

This manuscript discusses the role of lung transplantation in patients with pulmonary hypertension. The indications and timing for referral to a transplant unit and timing for wait-listing for lung transplantation are discussed. The type of transplantation—isolated (single or double) lung transplantation and situations when combined heart and double lung transplantation is indicated—will be elaborated. Escalation of medical therapy with the need and timing for bridging therapies such as extracorporeal membrane oxygenation until an appropriate organ becomes available will be discussed. Challenges in the postoperative period, specific to lung transplantation for pulmonary artery hypertension, will be reviewed. The outcomes following lung transplantation will also be considered in greater detail.

Lung Transplantation for Pulmonary Arterial Hypertension: Optimized Referral and Listing Based on an Evolving Disease Concept

Pulmonary hypertension (PH) was once a devastating and fatal disease entity, the outlook of which has been significantly improved by the continued progress of medical treatment algorithms. However, some patients still ultimately fail to achieve an adequate clinical response despite receiving maximal medical treatment. Historically, lung transplantation (LTx) has been the only effective therapeutic option that could lead to satisfactory outcomes and save these advanced patients' lives. However, patients with PH tend to have the highest mortality rates on the transplant waiting list; especially after comprehensive medical treatment, they continue to deteriorate very rapidly, eventually missing optimal transplantation windows. Balancing optimized medical treatment with the appropriate timing of referral and listing has been highly controversial in LTx for patients with PH. The 2021 consensus document for the selection of lung transplant candidates from the International Society for Heart and Lung Transplantation (ISHLT) updated the specific recommendations for the LTx referral and listing time for patients with PH based on objective risk stratification. Herein, we review the evolving PH-related concepts and highlight the optimization of LTx referral and listing for patients with PH, as well as their management on the waiting list.

Growing up with Idiopathic Pulmonary Arterial Hypertension: An Arduous Journey

Idiopathic pulmonary arterial hypertension (IPAH) is an uncommon and severe disease. We report the case of a 7-year-old boy investigated for cardiac murmur and exercise intolerance. Pulmonary hypertension (PH) was suspected at clinical examination and confirmed by echocardiography and cardiac catheterization. This case of pulmonary hypertension was classified as idiopathic given the negative etiological investigation. Vasoreactive testing with oxygen and nitric oxide was negative. Therefore, treatment with sildenafil (1.4 mg/kg/d) and bosentan (3 mg/kg/d) was initiated. This allowed the stabilization of, but not a decrease in, pulmonary artery pressure for the next 5 years, during which the patient's quality of life was significantly reduced. At a later follow-up, the estimated pulmonary pressure was found to have increased and become supra-systemic, with a consequent deterioration in the child's condition. This led to the decision to enter him into a clinical trial that is still ongoing. Idiopathic pulmonary arterial hypertension is a severe disease that can present with non-specific symptoms, such as asthenia and exercise limitation, which are important not to trivialize. The disease is associated with significantly decreased quality of life in affected children and carries a high burden in terms of mortality and morbidity. The current knowledge about IPAH in children is reviewed, with a particular focus on the future prospects for its treatment and the related quality of life of patients.

2022 Update of indications and contraindications for lung transplantation in France

Lung transplantation (LTx) is a steadily expanding field. The considerable developments have been driven over the years by indefatigable work conducted at LTx centers to improve donor and recipient selection, combined with multifaceted efforts to overcome challenges raised by the surgical procedure, perioperative care, and long-term medical complications. One consequence has been a pruning away of contraindications over time, which has, in some ways, complicated the patient selection process. The Francophone Pulmonology Society (Société de Pneumology de Langue Française, SPLF) set up a task force to produce up-to-date working guidelines designed to assist pulmonologists in managing end-stage respiratory insufficiency, determining which patients may be eligible for LTx, and appropriately timing LTx-center referral. The task force examined the most recent literature and evaluated the risk factors that limit patient survival after LTx. Ideally, the objectives of LTx are to prolong life while also improving quality of life. The guidelines developed by the task force apply to a limited resource and are consistent with the ethical principles described below.

Technical Aspects of Combined Heart-Lung Transplantation

Although organ transplants have become quite common, combined heart-lung transplantation (CHLTx) is unfamiliar at most institutions. While the remarkable rate of development in treatment options, such as drugs and mechanical circulatory support, have reduced the need for CHLTx, it remains the sole treatment option for a subset of patients with end-stage cardiopulmonary failure. For many cardiothoracic surgeons, CHLTx is not technically new or difficult, but it does pose challenges due to its low frequency and relative complexity. Thus, this review aims to describe the CHLTx technique in technical detail using the existing literature.

Donor selection for multiorgan transplantation

PURPOSE OF REVIEW

There is limited data and guidance on donor selection for multiorgan transplantation. In this article, we review the current Organ Procurement and Transplantation Network policy on multiorgan allocation and the ideal donor criteria for each specific organ, in order to provide a framework to guide donor selection for various scenarios of multiorgan transplantation, including heart-kidney, heart-lung, heart-liver and heart-kidney-liver transplant procedures.

RECENT FINDINGS

Combined heart-kidney transplantation is the most common multiorgan transplant procedure and requires the most stringent HLA matching to ensure optimal graft survival. Using the virtual crossmatch and desensitization therapies can shorten waitlist times without increasing posttransplant rejection or mortality rates. The ideal heart-lung donor tends to be younger than other multiorgan transplants, and more tolerant to HLA mismatch, but ideally requires donors with no prior history of smoking, a short period of time on mechanical ventilation, adequate oxygenation and absence of pulmonary infection. The ideal heart-liver donor is often driven by criteria specific to the donor heart. Finally, several observational studies suggest that livers are more tolerant to HLA mismatch than other organs, and offer some degree of immune protection in combined organ transplants.

SUMMARY

Multiorgan transplantation is a steadily growing field. The required short ischemic time for the donor heart is often the limiting factor, as well as the scarcity of appropriate donors available within geographical confines. In general, as with single organ transplantation, younger age, size matching, few medical comorbidities and HLA compatibility confer the best posttransplant outcomes.

Lung and heart-lung transplantation for children with PAH: Dramatic benefits from the implementation of a high-priority allocation program in France

PURPOSE

Pulmonary arterial hypertension (PAH) is rare but remains fatal in infants and children despite the advance of targeted therapies. Lung transplantation (LTx), first performed in pediatric patients in the 1980s, is, with the Potts shunt, the only potentially life-extending option in patients with end-stage PAH but is possible only in tightly selected patients. Size-matching challenges severely restrict the donor organ pool, resulting-together with peculiarities of PAH in infants-in high waitlist mortality. We aimed to investigate survival when using a high-priority allocation program (HPAP) in children with PAH listed for double-LTx or heart-LTx.

METHODS

We conducted a single-center, retrospective, before-after study of consecutive children with severe Group 1 PAH listed for double-LTx or heart-LTx between 1988 and 2019. The HPAP was implemented in France in 2006 and 2007 for heart-LTx and double-LTx, respectively.

RESULTS

Fifty-five children with PAH were listed for transplantation. Mean age at transplantation was 15.8±2.8 years and 72% had heart-lung transplantation. PAH was usually idiopathic (65%) or due to congenital heart disease (25%). HPAP implementation resulted in the following significant benefits: Decreased cumulative incidence of waitlist death within 1 and 2 years (p < 0.0001); increased cumulative incidence of transplantation within 6 months, from 44% to 67% (p < 0.01); and improved survival after listing (at 1, 3, and 5 years: 61%, 50%, and 44% vs. 92%, 84%, and 72% before and after HPAP implementation, respectively; p = 0.02).

CONCLUSION

HPAP implementation was associated with significant improvements in access to transplantation and in survival after listing in children with end-stage PAH.

Immunosuppression considerations in simultaneous organ transplant

Solid organ transplantation is a life-saving procedure for patients in the end stage of heart, lung, kidney, and liver failure. For patients with more than one failing organ, simultaneous organ transplantation has emerged as a viable treatment option. Immunosuppression strategies and outcomes for simultaneous organ transplant recipients have been reported, but often involve limited populations. Transplanting dual organs poses challenges in terms of balancing immunosuppression with immunologic risk and allograft damage from surgical complications. Furthermore, transplanting certain organs can impose considerations on the management of immunosuppression. For example, liver allografts may confer immunologic privilege and lower rates of rejection of other allografts. This review article evaluates immunosuppression strategies for simultaneous kidney-pancreas, liver-kidney, heart-kidney, heart-liver, heart-lung, lung-liver, and lung-kidney transplants. To date, no comprehensive review exists to address immunosuppressive strategies in simultaneous organ transplant populations. Our review summarizes the available literature and provides evidence-based recommendations regarding immunosuppression strategies in simultaneous organ transplant recipients.

Focused Update on Pulmonary Hypertension in Children-Selected Topics of Interest for the Adult Cardiologist

Pulmonary hypertensive vascular disease (PHVD), and pulmonary hypertension (PH), which is a broader term, are severe conditions associated with high morbidity and mortality at all ages. Treatment guidelines in childhood are widely adopted from adult data and experience, though big differences may exist regarding aetiology, concomitant conditions and presentation. Over the past few years, paediatric aspects have been incorporated into the common guidelines, which currently address both children and adults with pulmonary hypertension (PH). There are multiple facets of PH in the context of cardiac conditions in childhood. Apart from Eisenmenger syndrome (ES), the broad spectrum of congenital heart disease (CHD) comprises PH in failing Fontan physiology, as well as segmental PH. In this review we provide current data and novel aspects on the pathophysiological background and individual management concepts of these conditions. Moreover, we focus on paediatric left heart failure with PH and its challenging issues, including end stage treatment options, such as mechanical support and paediatric transplantation. PH in the context of rare congenital disorders, such as Scimitar Syndrome and sickle cell disease is discussed. Based on current data, we provide an overview on multiple underlying mechanisms of PH involved in these conditions, and different management strategies in children and adulthood. In addition, we summarize the paediatric aspects and the pros and cons of the recently updated definitions of PH. This review provides deeper insights into some challenging conditions of paediatric PH in order to improve current knowledge and care for children and young adults.