Pulmonary Homograft Research Articles

Long-term results of aortic arch reconstruction with branch pulmonary artery homograft patches.

Homograft tissue is an important reconstructive material used in the surgical correction of a variety of congenital heart defects. The aim of this study is to evaluate the long-term outcome of pulmonary artery(PA) branch patches used in the reconstruction of the thoracic aorta in children. Retrospective review of 124 consecutive pediatric patients undergoing corrective surgery for their congenital heart defects between 2001 and 2016. Survival, reoperation, and reintervention data were collected, as well as imaging data to assess for presence of recoarctation, dilation, or aneurysm formation in the area of patch reconstruction. Overall 15-year survival was 83.9% and 15-year freedom from reintervention in the area of patch reconstruction was 89.2%. Rates of mortality (0%), cardiac transplantation (0%), and reoperation (0.8%) attributable to the area of patch reconstruction were low. The frequency of catheter-based intervention in the area of patch reconstruction was 9.7%; such interventions were successful in all but one patient, who ultimately underwent successful surgical aortoplasty. Homograft patches harvested from PA branches are an effective reconstructive material used for reconstruction of the aorta in small children. Long-term results show no risk of aneurysm formation and low rates of stenosis formation.

TRANSCATHETER TREATMENT OF FAILED PULMONARY HOMOGRAFT

Aortic valve (AV) replacement with a pulmonary autograft (ROSS Procedure) has been used for treatment of aortic stenosis (AS), but degeneration of the aortic position pulmonary autograft and pulmonary position homograft often requires repeat surgical intervention. 63 year old male presented with

Pulmonary Artery Reconstruction After Failed Pulmonary Artery Stents

Pulmonary artery stents are widely deployed in patients with stenoses in the branch pulmonary arteries. However, stents do not address more peripheral sites of stenosis and invariably develop in-stent restenosis. The purpose of this study was to review our experience with pulmonary artery reconstruction after failed pulmonary artery stents. This was a retrospective study of 56 patients who underwent pulmonary artery reconstruction after failed pulmonary artery stents. These patients had undergone a median of 2 (range, 0-5) previous surgical procedures and 2 (range, 1-4) pulmonary artery stents. The median age at stent surgery was 5 (range, 0.3-23.6) years. The majority of stents (79%) were completely removed and patch augmented. The minority of stents (21%) were felt to be unremovable and thus were split longitudinally and reconstructed using a pulmonary artery homograft. There was 1 (1.8%) operative mortality. The mean pulmonary artery-to-aortic pressure ratio decreased from a preoperative value of 0.91 ± 0.21 to a postoperative value of 0.31 ± 0.07 (P < .001). The median hospital length of stay was 10 days. The median durationof follow-up was 1.8 years. There has been no midterm mortality. Six patients have undergone balloon dilation postoperatively for residual pulmonary artery stenosis. Pulmonary artery reconstruction resulted in a significant decrease in pulmonary artery-to-aortic pressure ratios. The subsequent need for reintervention on the pulmonary arteries has been relatively low (11% to date). These results suggest that patients with pulmonary artery stents can be successfully treated with surgical reconstruction.

Right Ventricular Outflow Tract Reconstruction in Infant Truncus Arteriosus: A 37-year Experience

Multiple conduits for right ventricular outflow tract reconstruction exist, although the ideal conduit that maximizes outcomes remains controversial. We evaluated long-term outcomes and compared conduits for right ventricular outflow tract reconstruction in children with truncus arteriosus. Records of patients who underwent truncus arteriosus repair at our institution between 1981 and 2018 were retrospectively reviewed. Primary outcomes included survival and freedom from catheter reintervention or reoperation. Secondary analyses evaluated the effect of comorbidity, operation era, conduit type, and conduit size. One hundred patients met inclusion criteria. Median follow-up time was 15.6 years (interquartile range, 5.3-22.2). Actuarial survival at 30 days, 5 years, 10 years, and 15 years was 85%, 72%, 72%, and 68%, respectively. Early mortality was associated with concomitant interrupted aortic arch (hazard ratio, 5.4; 95% confidence interval, 1.7-17.4; P= .005). Median time to surgical reoperation was 4.6 years (interquartile range, 2.9-6.8; n=58). Right ventricle to pulmonary artery continuity was established with an aortic homograft (n= 14), pulmonary homograft (n= 41), or bovine jugular vein conduit (n= 36) in most cases. Multivariate analysis revealed longer freedom from reoperation with the bovine jugular vein conduit compared with the aortic homograft (hazard ratio, 3.1; 95% confidence interval, 1.3-7.7; P= .02) with no difference compared with the pulmonary homograft. Larger conduit size was associated with longer freedom from reoperation (hazard ratio, 0.7; 95% confidence interval, 0.6-0.9; P < .001). The bovine jugular vein conduit is a favorable conduit for right ventricular outflow tract reconstruction in patients with truncus arteriosus. Concomitant interrupted aortic arch is a risk factor for early mortality.

Infective Endocarditis 2 Decades After Pulmonary Autograft Ross Procedure

Pulmonary autograft, or Ross procedure, is performed by supplanting a diseased aortic valve with the patient’s own pulmonary valve. Reconstruction of the right ventricular outflow tract is then completed using a pulmonary homograft. To our knowledge, infective endocarditis occurring decades after the Ross procedure has not been reported. Diligent echocardiographic examination can be crucial to ensure prompt treatment and avoid the 25% mortality rate associated with infective endocarditis. Clinical suspicion should remain high in those with a pulmonary autograft history. In this article, we report the case of a 39-year-old patient with infective endocarditis presenting 22 years after Ross procedure.

Mycobacterium chimaera in a post thaw pulmonary valve homograft as a result of contaminated heater cooler unit in use during the implant surgery.

Mycobacterium chimaera in a post thaw pulmonary valve homograft as a result of contaminated heater cooler unit in use during the implant surgery.

Sustained Total All-Region (STAR) Perfusion for Norwood Reconstruction

The acute phase of recovery following the Norwood procedure can be complicated by considerable instability due in part to bleeding, acute kidney injury, systemic inflammatory response, and low cardiac function. The traditional conduct of cardiopulmonary bypass with cooling, re-warming, myocardial ischemia, and upper or lower body ischemia likely exacerbates these problems. Total body perfusion during Norwood reconstruction, without significant cooling or ischemic time to any organs, may improve postoperative recovery by reducing coagulopathy and end-organ injury. Here, we introduce a novel technique for sustained total all-region perfusion of the heart, upper body, and lower body throughout the Norwood operation.

More Than 25 Years of Experience With the Ross Procedure in Children: A Single-Center Experience

Aortic valve replacement in children represents an important challenge. Concerns regarding pulmonary autograft and homograft longevity requiring reoperations are well recognized. Very long-term outcomes after the Ross procedure are still unknown. We reviewed our experience with the Ross procedure, aiming to define very long-term survival rate and freedom from reintervention. This was a single-center retrospective cohort including 63 consecutive children who underwent the Ross procedure. Median follow-up duration was 20.5 years. Time-related events were assessed using Kaplan-Meier estimator. There were 51 (81%) boys, mean age 10.1 ± 5.8 years. Isolated aortic stenosis was the most common diagnosis (n= 29, 46%) and 34 (54%) patients previously underwent cardiac surgery. There was 1 (1.6%) in-hospital death. Overall survival at 5, 15, and 25 years was 96.7%, 94.4%, and 94.4%, respectively. Freedom from any autograft-related reintervention was 98.1%, 86.4%, and 61.2% at 5, 15, and 25 years, respectively. Fifteen (24%) patients underwent autograft reoperations. Among them, 10 (67%) patients underwent valve-sparing autograft reoperation. Freedom from any pulmonary conduit reintervention was 93.2%, 58.2%, and 28.3% at 5, 15, and 25 years, respectively. Thirty (46.6%) patients underwent conduit reintervention (8 percutaneous, 22 surgical replacements). The pediatric Ross procedure is associated with excellent long-term survival. Ross-related reinterventions are more than twice as common on the pulmonary homograft than on the autograft.

Bovine jugular vein conduit versus pulmonary homograft in the Ross operation.

The Ross procedure involves using the native pulmonary valve for aortic valve replacement then replacing the pulmonary valve with an allograft or xenograft. We aimed to compare our age-matched experience with the bovine jugular vein conduit and the pulmonary homograft for pulmonary valve replacement during the Ross procedure in children. Between 1998 and 2016, 15 patients <18 years of age underwent a Ross procedure using the bovine jugular vein conduit (Ross-Bovine Jugular Vein Conduit) at our institution. These patients were age-matched with 15 patients who had the Ross operation with a standard pulmonary homograft for right ventricular outflow tract reconstruction (Ross-Pulmonary Homograft). Paper and electronic medical records were retrospectively reviewed. The median age of the Ross-Bovine Jugular Vein Conduit and Ross-Pulmonary Homograft patients were 4.8 years (interquartile range 1.1-6.6) and 3.3 years (interquartile 1.2-7.6), respectively (p = 0.6). The median follow-up time for the Ross-Bovine Jugular Vein Conduit and Ross-Pulmonary Homograft groups were 1.7 years (interquartile range 0.5-4.9) and 6.8 years (interquartile range 1.9-13.4), respectively (p = 0.03). Overall, 5-year survival, freedom from redo aortic valve replacement, and freedom from pulmonary valve replacement were similar between groups. The bovine jugular vein conduit and pulmonary homograft have favourable mid-term durability when used for right ventricular outflow tract reconstruction for the Ross operation. The bovine jugular vein conduit may be a suitable replacement for appropriately sized patients undergoing a Ross aortic valve replacement, though longer follow-up is needed.

IL-22 is required for the induction of bronchus-associated lymphoid tissue in tolerant lung allografts.

Long-term survival after lung transplantation remains profoundly limited by graft rejection. Recent work has shown that bronchus-associated lymphoid tissue (BALT), characterized by the development of peripheral nodal addressin (PNAd)-expressing high endothelial venules and enriched in B and Foxp3+ T cells, is important for the maintenance of allograft tolerance. Mechanisms underlying BALT induction in tolerant pulmonary allografts, however, remain poorly understood. Here, we show that the development of PNAd-expressing high endothelial venules within intragraft lymphoid follicles and the recruitment of B cells, but not Foxp3+ cells depends on IL-22. We identify graft-infiltrating gamma-delta (γδ) T cells and Type 3 innate lymphoid cells (ILC3s) as important producers of IL-22. Reconstitution of IL-22 at late time points through retransplantation into wildtype hosts mediates B cell recruitment into lymphoid follicles within the allograft, resulting in a significant increase in their size, but does not induce PNAd expression. Our work has identified cellular and molecular requirements for the induction of BALT in pulmonary allografts during tolerance induction and may provide a platform for the development of new therapies for lung transplant patients.

Ultrastructural changes in pulmonary allografts with antibody-mediated rejection

Antibody-mediated rejection (AMR) is an important cause of lung allograft loss in some patients. Challenges with current diagnostic criteria limit timely detection. Ultrastructural studies of endothelia allow the early detection of AMR in kidney allografts. This study aimed to define the ultrastructural changes of the endothelium in lung allografts in the setting of AMR and determine its specificity for AMR. Ultrastuctural studies were performed on lung allograft biopsies of 12 patients using glutaraldehyde-fixed or paraffin-embedded material. AMR had been classified according to the International Society of Heart and Lung Transplant 2016 consensus report criteria. Endothelial changes (swelling [ES], vacuolization [EV], surface irregularity, detachment, neutrophil margination [NM]) and basement membrane changes were graded semi quantitatively using electron microscopy (EM). Grades were compared between AMR, acute cellular rejection, and non-transplant controls. Significant differences were found between AMR and acute cellular reaction biopsies, particularly in ES (p = 0.006), EV (p = 0.023) and NM (p = 0.038). Using a combined score of all categories of assessment, the total EM score was significantly higher in AMR (p = 0.007) and provided excellent sensitivity and specificity with a receiver operator characteristic curve of 1.0. C4d did not correlate with EM changes associated with AMR. The use of paraffin-embedded material samples did not significantly affect the analysis compared with glutaraldehyde-fixed tissue, although ES was reduced in the former. Endothelial structural analysis using EM can facilitate improved diagnostic accuracy of AMR and needs to be validated in larger cohorts, but it also allows retrospective studies to be performed.

Favorable Outcome of Lung Transplantation for Severe Pulmonary Graft Versus Host Disease: An Australian Multicenter Case Series.

Severe pulmonary chronic graft versus host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic stem cell transplantation. Few treatments influence outcome, with 5-year overall survival as low as 13%. Lung transplantation (LTx) has been reported in small numbers of patients worldwide. We investigated the outcomes of LTx performed for this indication at 2 large Australian LTx centers. Eighteen patients (aged 10-64 y; median, 29.6 y) received bilateral deceased lung transplants for pulmonary chronic GVHD between 2002 and 2017. LTx was performed at a median of 8.6 years after allogeneic stem cell transplantation (range, 2-23 y) with a median interval of 16 months from the time of transplant unit review to LTx. There were 2 early infective deaths and 3 further deaths from pulmonary infection and lung allograft rejection. There were no primary disease relapses. At a median follow-up of 5 years, the 5-year overall survival post-LTx is 80% and comparable to the Australia and New Zealand registry data of 64% for LTx performed for all indications. From one of the largest series of deceased LTx for this indication, we conclude that it is a feasible option for selected patients with severe pulmonary GVHD. The outcomes appear superior to that of non-LTx-based therapies and similar to the survival of the general LTx population. Establishing guidance on referral triggers, patient eligibility, organ selection, prophylaxis of allograft rejection, and supportive care would assist hematopoietic and lung transplant units in optimizing resource allocation and patient outcomes.

Pulmonary Valve Function Late After Ross Procedure in 443 Adult Patients

Limited data exist on long-term pulmonary valve function after the Ross procedure. This study sought to determine the long-term function of the pulmonary valve in 443 consecutive adult patients who underwent a Ross procedure. All 443 patients who underwent a Ross procedure between November 1992 and March 2018 were reviewed retrospectively. All underwent pulmonary valve replacement using a cryopreserved pulmonary allograft. Freedom from the study's outcomes were calculated using Kaplan Meier survival. Risk factors for valve failure were analyzed using Cox regression. Mean age at time of operation was 39 years (range: 15-66 years). There was 1 (0.2%, 1 of 443) operative mortality. Nine patients required reintervention on the pulmonary allograft at a mean 6.1 years (range: 1-12 years) after Ross procedure. Patients required pulmonary allograft reintervention for infective endocarditis (n= 4), severe pulmonary stenosis (n= 4), or severe pulmonary regurgitation (n= 1). Freedom from pulmonary allograft reintervention was 98.9% (95% confidence interval [CI] 97.1%-99.6%), 97.7% (95% CI 95.1%-98.9%), 96.6% (95% CI 93.3%-98.3%), and 96.6% (95% CI 93.3%-98.3%) at 5, 10, 15, and 20 years, respectively. Freedom from pulmonary allograft dysfunction (at least moderate pulmonary regurgitation and/or mean systolic gradient ≥ 25 mm Hg and/or reintervention) was 94.5% (95% CI 91.6%-96.4%), 88.1% (95% CI 83.6%-91.4%), 84.9% (95% CI 79.6%-88.9%), and 78.3% (95% CI 69.5%-84.9%) at 5, 10, 15, and 20 years, respectively. No risk factors were identified to influence pulmonary valve durability. The pulmonary valve allograft gives excellent long-term function when used in adults undergoing the Ross procedure. Reintervention on the pulmonary valve is rare and significant pulmonary allograft dysfunction is uncommon.

Outcome of 40 consecutive cases of modified Ross procedure using novel Dacron valved conduit.

The Ross procedure is an established option for aortic valve disease in children. Due to limited availability of pulmonary homograft, we devised a novel technique for right ventricular outflow tract (RVOT) reconstruction by preparing indigenous Dacron valved conduit. Forty consecutive cases of modified Ross procedure done at our center (2013-2018) were analyzed. Thirty-seven patients (95%) were followed up with median duration of 2.5 (0.08-5.5) years. Median age was 12 (5-39) years. Nineteen (47.5%) patients had rheumatic aortic valve disease, while 19 (47.5%) had congenital aortic valve disease. Aortic root replacement with pulmonary autograft was performed in all patients. Dacron conduit for RVOT reconstruction was used with on table sewn bileaflet valve using Dacron patch (n = 22), expanded polytetrafluoroethylene (ePTFE) membrane (n = 10), bioprosthetic valve (n = 4), and pericardium (n = 4). Additional surgical procedures included mitral valve repair (n = 10), septal myectomy (n = 2), ascending aorta replacement (n = 1), ruptured sinus of valsalva (RSOV) repair (n = 1), and ventricular septal defect (VSD) closure (n = 1). There was one in-hospital mortality while one late death occurred at 3.5years postoperatively. The neo-aortic valve regurgitation on echocardiographic evaluation at last follow-up was trivial (n = 28), mild (n = 7), and moderate (n = 2). Mild RVOT obstruction was present in 8 patients while 18 patients had mild pulmonary regurgitation. No patient required reintervention during follow-up. Our early results of modified Ross procedure are encouraging, however, long-term follow-up is required.

Impact of the Opioid Epidemic on Lung Transplantation: Donor, Recipient, and Discard Characteristics

The national opioid epidemic may have expanded the donor pool for lung transplant, but concerns remain regarding infectious risks and allograft function. This study compared donor and recipient characteristics, outcomes, and reasons for organ discard between overdose death donors (ODDs) and all other mechanism-of-death donors. Data on adult lung transplants from 2000 to 2017 were provided by the Scientific Registry of Transplant Recipients. Pulmonary allografts used in multiple organ transplants were excluded. Donor and recipient demographics, outcomes, and organ discard were analyzed with regards to ODDs since 2010. Discard analysis was limited to donors who had at least 1 organ transplanted but their pulmonary allografts discarded. From 2010 to 2017, 7.3% of lung transplants (962/13,196) were from ODDs, over a 3-fold increase from the 2.1% (164/7969) in 2000 to 2007. ODDs were younger but more likely to have a history of smoking and hepatitis C or an abnormal bronchoscopy finding. Overall survival was similar between ODD and non-ODD groups. ODDs of discarded pulmonary allografts were younger and more likely to be hepatitis C positive but were less likely to have a history of smoking than their non-ODD counterparts. Rates of ODD use in lung transplant have increased in accordance with the opioid epidemic, but there remains a significant pool of ODD pulmonary allografts with favorable characteristics that are discarded. With no significant difference in survival between ODD and non-ODD recipients, further expansion of this donor pool may be appropriate, and pulmonary allografts should not be discarded based solely on ODD status.

Aortic or Pulmonary Valved Homograft Right Ventricle to Pulmonary Artery Conduit in the Norwood Procedure.

Several modifications of the Norwood procedure utilizing valved right ventricle to pulmonary artery conduits have recently been reported. Our group has been using aortic or pulmonary valved homografts combined with PTFE tube grafts for now 16 years. In this report, we review our technique in detail and describe any changes that have occurred over the years. We provide detailed illustrations of our preferred surgical technique, report outcome data, and compare it to the other conduit options available. Between 2006 and 2015, 130 stage I Norwood procedures were performed at our institution, 100 of them using valved conduits. Our technique is described and illustrated in detail. Early mortality was 15%. Postoperative percutaneous intervention on the conduit was required in 29% of cases. While a randomized trial comparing different valved conduits is lacking, we believe a composite conduit made from homograft aortic or pulmonary valves and PTFE tube grafts is an excellent choice in stage I Norwood procedure.

Subcoronary Technique for Orthotopic Implantation of Aortic Scaffold Reinforced with Polytetrafluoroethylene Strips in Sheep: A pilot Study

Over the time, numerous studies have been reported describing successful pulmonary valve replacement, either with xenografts or allografts, performed in sheep model. In contrast, comparable results have not been achieved yet for aortic valve replacement in orthotopic position, which involves a more difficult surgical technique, high hemodynamic demands for the implanted valve and poor survival of animals undergoing this kind of surgery. To our knowledge, in Romania, these were the first orthotopic allogeneic aortic root implantations using the subcoronary technique, carried out by our team. We established feasible perioperative, anesthetic and surgical protocols, which will be used in future studies to evaluate the in vivo functional performances of decellularized valves compared with autologous adipose derived stem cells seeded valves. Therefore, a unique research core was created, which is currently the only center of this kind in our country, by joining a multidisciplinary team consisting of biomedical engineers, cardiovascular surgeons, anesthesiologists, cardiologists, pathologists, microbiologists and veterinarians, who will continue the research activity in the field of tissue engineering and translate experimental results into clinical activity.

Lung transplantation : Histomorphological diagnosis and clinical aspects

The function of pulmonary allografts is regularly impaired by alloimmune reactions with quite variable clinical outcomes, different involved effector cells and molecules, as well as affected anatomical compartments. Acute rejection of grafts after lung transplantation (LuTx) is not only associated with the subsequent development of acute graft dysfunction, but can also contribute - among other immunological and nonimmunological factors - to the development of chronic lung allograft dysfunction (CLAD), which is the main reason for the limited long-term survival after LuTx. In addition to ACR and analogous to other solid organ transplants, the importance of antibody-mediated (humoral) rejection (AMR) in LuTx has also been recognized. There are currently no specific laboratory, radiological, or clinical tests available for either ACR or AMR. Only by the synoptic examination of histopathological changes and interpretation against the background of microbiological, virological, serological, and functional findings, can adequate sensitivity and specificity be achieved in the diagnostics of rejection. In this article, the current criteria for histopathological diagnostics of rejection following LuTx are summarized and the most important differential diagnoses are discussed.

Audit of homograft valve bank.

Even today, the search for the ideal cardiac valve continues. With advantages of having superior flow dynamics, avoidance of anticoagulation, and resistance to infection, homograft has been shown to have an edge over conventional prosthetic and bioprosthetic valves. But they suffer from disadvantages of limited availability and durability. Our center operates one of the oldest functioning valve banks in the country. We present our experience with homograft valve banking with antibiotic and cryopreserved homografts spread over a quarter century. For donor selection, procurement, sterilization, and preservation, the recommendations of the American Association of Tissue Banks are being followed in accordance with statutory provisions of the Transplantation of Human Organs Act, 1994. During 25-year period (1993-2017), 777 hearts were procured. Age of the donors ranged from 2 to 60years and hearts were procured within 24h of death. A total of 1646 homografts (774 pulmonary, 774 aortic, 60 mitral valves, 20 descending thoracic aortae, and 18 monocusps) were harvested. A total of 546 (32%) homografts were rejected for various reasons. Nine hundred sixty-seven (56.7%) homografts were used in different procedures. Of these, 478 were pulmonary homografts, 425 were aortic homografts, 39 mitral homografts, 18 monocusps, and 7 descending thoracic aorta homografts. One hundred fifty-four (16%) homografts were antibiotic preserved and the rest 813 (84%) were cryopreserved. It is possible to run a homograft valve bank with minimum costs. Though, cryopreservation is more expensive, it provides an opportunity to store the valves for an indefinite period and maintain an uninterrupted supply of homografts.

Performance of Decellularized and Non-decellularized Cryopreserved Pulmonary Homografts Used for the Reconstruction of the Right Ventricular Outflow Tract in the Ross Procedure: A Comparison

Objective: Structural degeneration is the main cause of hemodynamic deterioration and failure of homografts. Immune-mediated processes seem to have a key role. The decellularization of homografts a...