Bilateral orthotopic lung transplant via a clamshell thoracosternotomy from a donor with extended cold static lung preservation.

In this video tutorial, we present a comprehensive step-by-step operative technique for a bilateral orthotopic lung transplant using a bilateral transverse thoracosternotomy in a patient with idiopathic pulmonary fibrosis lung disease. The donor lungs were exposed to extended cold static ischaemic storage at 10° C for the semi-elective operation.

Dual lumen venopulmonary extracorporeal membrane oxygenation cannulation technique using the ProtekDuo.

In this video tutorial, we present the cannulation technique for venopulmonary extracorporeal membrane oxygenation using the ProtekDuo dual-lumen cannula in a patient with acute respiratory distress syndrome.

MerTK-dependent efferocytosis by monocytic-MDSCs mediates resolution of post-lung transplant injury.

Rationale: Patients with end stage lung diseases require lung transplantation (LTx) that can be impeded by ischemia-reperfusion injury (IRI) leading to subsequent chronic lung allograft dysfunction (CLAD) and inadequate outcomes. Objectives: We examined the undefined role of MerTK (receptor Mer tyrosine kinase) on monocytic myeloid-derived suppressor cells (M-MDSCs) in efferocytosis (phagocytosis of apoptotic cells) to facilitate resolution of lung IRI. Methods: Single-cell RNA sequencing of lung tissue and BAL from post-LTx patients was analyzed. Murine lung hilar ligation and allogeneic orthotopic LTx models of IRI were used with Balb/c (WT), cebpb -/- (MDSC-deficient), Mertk -/- or MerTK-CR (cleavage resistant) mice. Lung function, IRI (inflammatory cytokine and myeloperoxidase expression, immunohistology for neutrophil infiltration), and flow cytometry of lung tissue for efferocytosis of apoptotic neutrophils were assessed in mice. Measurements and Main Results: A significant downregulation in MerTK-related efferocytosis genes in M-MDSC populations of CLAD patients compared to healthy subjects was observed. In the murine IRI model, significant increase in M-MDSCs, MerTK expression and efferocytosis was observed in WT mice during resolution phase that was absent in cebpb -/- Land Mertk -/- mice. Adoptive transfer of M-MDSCs in cebpb -/- mice significantly attenuated lung dysfunction, and inflammation leading to resolution of IRI. Additionally, in a preclinical murine orthotopic LTx model, increases in M-MDSCs were associated with resolution of lung IRI in the transplant recipients. In vitro studies demonstrated the ability of M-MDSCs to efferocytose apoptotic neutrophils in a MerTK-dependent manner. Conclusions: Our results suggest that MerTK-dependent efferocytosis by M-MDSCs can significantly contribute to the resolution of post-LTx IRI.

Thoracoliths in Pleural Space Mimicking Lung Cancer: A Case Report.

Pulmonary nodules often present a diagnostic challenge due to their diverse etiology, ranging from benign to malignant conditions. We discuss the diagnostic journey of a 71-year-old female patient with a history of kidney stones, who was incidentally found to have a pleural-based pulmonary nodule during a CT urogram. Subsequent imaging showed nodule growth, prompting further investigations, including a PET/CT scan and CT-guided biopsy, which yielded inconclusive results. A multidisciplinary approach recommended surgical resection, revealing three mobile calcified-like nodules within the pleural space, later identified as hyalinized nodules. The absence of malignancy was reassuring. These benign, mobile pleural bodies, known as thoracoliths, are challenging to differentiate from pulmonary nodules. This case underscores the importance of considering rare benign entities in pulmonary nodule differentials and highlights the need for a multidisciplinary approach, surgical intervention, and open-mindedness in complex diagnostic scenarios.

Intralobar pulmonary sequestration presenting as recurrent left lower lobe pneumonia.

This case discusses the diagnosis and management of pulmonary sequestration. Typically discovered incidentally on imaging, it can be a cause of recurrent pulmonary infections causing severe morbidity to the patient. Surgical management is indicated when found to prevent the complications of recurrent infections, including pulmonary necrosis, abscess, or fistula formation.

Intraoperative Hemi-Diaphragm Electrical Stimulation Demonstrates Attenuated Mitochondrial Function without Change in Oxidative Stress in Cardiothoracic Surgery Patients.

Mechanical ventilation during cardiothoracic surgery is life-saving but can lead to ventilator-induced diaphragm dysfunction (VIDD) and prolong ventilator weaning and hospital length of stay. Intraoperative phrenic nerve stimulation may preserve diaphragm force production to offset VIDD; we also investigated changes in mitochondrial function after stimulation. During cardiothoracic surgeries (n = 21), supramaximal, unilateral phrenic nerve stimulation was performed every 30 min for 1 min. Diaphragm biopsies were collected after the last stimulation and analyzed for mitochondrial respiration in permeabilized fibers and protein expression and enzymatic activity of biomarkers of oxidative stress and mitophagy. Patients received, on average, 6.2 ± 1.9 stimulation bouts. Stimulated hemidiaphragms showed lower leak respiration, maximum electron transport system (ETS) capacities, oxidative phosphorylation (OXPHOS), and spare capacity compared with unstimulated sides. There were no significant differences between mitochondrial enzyme activities and oxidative stress and mitophagy protein expression levels. Intraoperative phrenic nerve electrical stimulation led to an acute decrease of mitochondrial respiration in the stimulated hemidiaphragm, without differences in biomarkers of mitophagy or oxidative stress. Future studies warrant investigating optimal stimulation doses and testing post-operative chronic stimulation effects on weaning from the ventilator and rehabilitation outcomes.

Reproducing extracellular matrix adverse remodelling of non-ST myocardial infarction in a large animal model.

The rising incidence of non-ST-segment elevation myocardial infarction (NSTEMI) and associated long-term high mortality constitutes an urgent clinical issue. Unfortunately, the study of possible interventions to treat this pathology lacks a reproducible pre-clinical model. Indeed, currently adopted small and large animal models of MI mimic only full-thickness, ST-segment-elevation (STEMI) infarcts, and hence cater only for an investigation into therapeutics and interventions directed at this subset of MI. Thus, we develop an ovine model of NSTEMI by ligating the myocardial muscle at precise intervals parallel to the left anterior descending coronary artery. Upon histological and functional investigation to validate the proposed model and comparison with STEMI full ligation model, RNA-seq and proteomics show the distinctive features of post-NSTEMI tissue remodelling. Transcriptome and proteome-derived pathway analyses at acute (7 days) and late (28 days) post-NSTEMI pinpoint specific alterations in cardiac post-ischaemic extracellular matrix. Together with the rise of well-known markers of inflammation and fibrosis, NSTEMI ischaemic regions show distinctive patterns of complex galactosylated and sialylated N-glycans in cellular membranes and extracellular matrix. Identifying such changes in molecular moieties accessible to infusible and intra-myocardial injectable drugs sheds light on developing targeted pharmacological solutions to contrast adverse fibrotic remodelling.

Survival After Lung Transplantation for Chronic Hypersensitivity Pneumonitis: Results From a Large International Cohort Study.

Repeated exposure to antigens via inhalation is the primary cause of hypersensitivity pneumonitis, a form of interstitial pneumonia. The chronic form of hypersensitivity pneumonitis leads to progressive loss of respiratory function; lung transplantation is the only therapeutic option for chronically ill patients. The ESTS Lung Transplantation Working Group conducted a retrospective multicentred cohort study to increase the body of knowledge available on this rare indication for lung transplantation. Data were collected for every patient who underwent lung transplant for hypersensitivity pneumonitis in participating centres between December 1996 and October 2019. Primary outcome was overall survival; secondary outcome was freedom from chronic lung allograft dysfunction. A total of 114 patients were enrolled from 9 centres. Almost 90% of patients were diagnosed with hypersensitivity pneumonitis before transplantation, yet the antigen responsible for the infection was identified in only 25% of cases. Eighty per cent of the recipients received induction therapy. Survival at 1, 3, and 5 years was 85%, 75%, and 70%, respectively. 85% of the patients who survived 90 days after transplantation were free from chronic lung allograft dysfunction after 3 years. The given study presents a large cohort of HP patients who underwent lung transplants. Overall survival rate is higher in transplanted hypersensitivity pneumonitis patients than in those suffering from any other interstitial lung diseases. Hypersensitivity pneumonitis patients are good candidates for lung transplantation.

Macrophage activating syndrome causing decompensated right heart failure.

BACKGROUND: Macrophage activating syndrome (MAS) is a form of hemophagocytic lymphohistiocytosis (HLH), a rare complication of autoimmune disease that is characterized by cytokine storm and multiorgan failure. CASE SUMMARY: A 32-year-old male presented with acutely decompensated pulmonary arterial hypertension and right heart failure secondary to MAS. The patient was immediately started on inhaled and intravenous epoprostenol, vasopressors and dexamethasone and anakinra were administered. Despite the therapies given, the patient's condition continued to decline, and he was placed on veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support. Over a few days, his clinical condition improved, and he was decannulated from VA-ECMO and later transitioned oral treprositinil and was discharged home. Due to its non-specific clinical manifestations, the diagnosis of MAS depends on high clinical suspicion and initial laboratory work up such as thrombocytopenia, transaminitis, hyperferritinemia, hypertriglyceridemia, hypofibrinogenemia, etc. In our patient, MAS led to decompensated Pulmonary Arterial Hypertension (PAH) leading to right heart failure that was refractory to inhaled and intravenous epoprostenol and vasopressors and required VA-ECMO as a bridge to recovery while his MAS was managed by anakinra and dexamethasone. CONCLUSION: MAS can result in acute decompensation of PAH and right heart failure. Besides RV failure management, immunosuppressants such as anakinra, etoposide, etc. should be utilized early in the management of MAS. In refractory right heart failure, VA-ECMO can be considered as a bridge to recovery. There is a paucity of literature supporting the utilization of VA-ECMO in the management of refractory right heart failure caused by MAS in adults and much of the data stems from pediatric studies. This case serves as a fine example of successful use of VA-ECMO in adult population.

Early outcomes after lung transplantation for severe COVID-19: a series of the first consecutive cases from four countries.

BACKGROUND: Lung transplantation is a life-saving treatment for patients with end-stage lung disease; however, it is infrequently considered for patients with acute respiratory distress syndrome (ARDS) attributable to infectious causes. We aimed to describe the course of disease and early post-transplantation outcomes in critically ill patients with COVID-19 who failed to show lung recovery despite optimal medical management and were deemed to be at imminent risk of dying due to pulmonary complications. METHODS: We established a multi-institutional case series that included the first consecutive transplants for severe COVID-19-associated ARDS known to us in the USA, Italy, Austria, and India. De-identified data from participating centres-including information relating to patient demographics and pre-COVID-19 characteristics, pretransplantation disease course, perioperative challenges, pathology of explanted lungs, and post-transplantation outcomes-were collected by Northwestern University (Chicago, IL, USA) and analysed. FINDINGS: Between May 1 and Sept 30, 2020, 12 patients with COVID-19-associated ARDS underwent bilateral lung transplantation at six high-volume transplant centres in the USA (eight recipients at three centres), Italy (two recipients at one centre), Austria (one recipient), and India (one recipient). The median age of recipients was 48 years (IQR 41-51); three of the 12 patients were female. Chest imaging before transplantation showed severe lung damage that did not improve despite prolonged mechanical ventilation and extracorporeal membrane oxygenation. The lung transplant procedure was technically challenging, with severe pleural adhesions, hilar lymphadenopathy, and increased intraoperative transfusion requirements. Pathology of the explanted lungs showed extensive, ongoing acute lung injury with features of lung fibrosis. There was no recurrence of SARS-CoV-2 in the allografts. All patients with COVID-19 could be weaned off extracorporeal support and showed short-term survival similar to that of transplant recipients without COVID-19. INTERPRETATION: The findings from our report show that lung transplantation is the only option for survival in some patients with severe, unresolving COVID-19-associated ARDS, and that the procedure can be done successfully, with good early post-transplantation outcomes, in carefully selected patients. FUNDING: National Institutes of Health. VIDEO ABSTRACT.

Deceased-donor lobar lung transplant: A successful strategy for small-sized recipients.

OBJECTIVES: Lobar lung transplantation (LLTx) from deceased donors is a potential solution for donor-recipient size mismatch for small sized recipients. We reviewed our institutional experience to compare outcomes after LLTx to standard lung transplantation (LTx). METHODS: We retrospectively reviewed transplants in our institution from January 2000 to December 2017. LLTx early- and long-term outcomes were compared with LTx. Additional analysis of outcomes was performed after dividing the cohort into 2 eras (era 1, 2000-2012; era 2, 2013-2017). RESULTS: Among the entire cohort (1665), 75 were LLTx (4.5%). Compared with LTx, LLTx were more frequently bridged to transplant with extracorporeal life support or mechanical ventilation and were transplanted in a rapidly deteriorating status (respectively, 20% vs 4.4%, P = .001; 22.7% vs 7.9, P < .001; and 41.3% vs 26.5%, P = .013). LLTx had longer intensive care unit and hospital lengths of stay (respectively, median 17 vs 4 days, and 45 vs 23, both P < .001), and greater 30-day mortality (13.3% vs 4.3%, P = .001) and 90-day mortality (17.3% vs 7.2%, P = .003). In era 2, despite a significantly greater 30-day mortality (10.8% vs 2.8%, P = .026), there was no significant difference in 90-day mortality between LLTx and LTx (13.5% vs 5.1%, P = .070). Overall survival at 1, 3, and 5 years was not significantly different between LLTx and LTx (73.2% vs 84.4%, 56.9% vs 68.4% and 50.4% vs 55.8, P = .088). CONCLUSIONS: Although LLTx is a high-risk procedure, both mid- and long-term survival are comparable with LTx in all cohorts in the modern era. LLTx therefore represents a valuable surgical option for small-sized recipients.

Rare indications for a lung transplant. A European Society of Thoracic Surgeons survey.

OBJECTIVES: The European Society of Thoracic Surgeons Lung Transplantation Working Group promoted a survey to evaluate overall survival in a large cohort of patients receiving lung transplants for rare pulmonary diseases. METHODS: We conducted a retrospective multicentre study. The primary end point was overall survival; secondary end points were survival of patients with the most common diagnoses in the context of rare pulmonary diseases and chronic lung allograft dysfunction (CLAD)-free survival. Finally, we analysed risk factors for overall survival and CLAD-free survival. RESULTS: Clinical records of 674 patients were extracted and collected from 13 lung transplant centres; diagnoses included 46 rare pulmonary diseases. Patients were followed for a median of 3.1 years. The median survival after a lung transplant was 8.5 years. The median CLAD-free survival was 8 years. The multivariable analysis for mortality identified CLAD as a strong negative predictor [hazard ratio (HR) 6.73)], whereas induction therapy was a protective factor (HR 0.68). The multivariable analysis for CLAD occurrence identified induction therapy as a protective factor (HR 0.51). When we stratified patients by CLAD occurrence in a Kaplan-Meier plot, the survival curves diverged significantly (log-rank test: P < 0.001). Patients with rare diseases who received transplants had chronic rejection rates similar to those of the general population who received transplants. CONCLUSIONS: We observed that overall survival and CLAD-free survival were excellent. We support the practice of allocating lungs to patients with rare pulmonary diseases because a lung transplant is both effective and ethically acceptable.

Exogenous connexin43-expressing autologous skeletal myoblasts ameliorate mechanical function and electrical activity of the rabbit heart after experimental infarction.

Acute myocardial infarction is one of the major causes of mortality worldwide. For regeneration of the rabbit heart after experimentally induced infarction we used autologous skeletal myoblasts (SMs) due to their high proliferative potential, resistance to ischaemia and absence of immunological and ethical concerns. The cells were characterized with muscle-specific and myogenic markers. Cell transplantation was performed by injection of cell suspension (0.5 ml) containing approximately 6 million myoblasts into the infarction zone. The animals were divided into four groups: (i) no injection; (ii) sham injected; (iii) injected with wild-type SMs; and (iv) injected with SMs expressing connexin43 fused with green fluorescent protein (Cx43EGFP). Left ventricular ejection fraction (LVEF) was evaluated by 2D echocardiography in vivo before infarction, when myocardium has stabilized after infarction, and 3 months after infarction. Electrical activity in the healthy and infarction zones of the heart was examined ex vivo in Langendorff-perfused hearts by optical mapping using di-4-ANEPPS, a potential sensitive fluorescent dye. We demonstrate that SMs in the coculture can couple electrically not only to abutted but also to remote acutely isolated allogenic cardiac myocytes through membranous tunnelling tubes. The beneficial effect of cellular therapy on LVEF and electrical activity was observed in the group of animals injected with Cx43EGFP-expressing SMs. L-type Ca(2+) current amplitude was approximately fivefold smaller in the isolated SMs compared to healthy myocytes suggesting that limited recovery of LVEF may be related to inadequate expression or function of L-type Ca(2+) channels in transplanted differentiating SMs.

Surgical treatment of non-malignant laryngotracheal stenosis.

The objectives of this study were the following: (1) to analyze the results of surgical treatment of non-malignant subglottic laryngeal and tracheal stenosis, (2) to evaluate the feasibility and technical aspects of the video mediastinoscopy for the mobilization of the mediastinal trachea, (3) to evaluate the influence of the early internal condition of the anastomosis on the development of restenosis. From 1996 up to 2013, 75 patients aged 11-78 years underwent surgery for post-intubation/tracheostomy (71 patients), post-traumatic (3 patients), and idiopathic (1 patient) subglottic laryngeal and tracheal stenosis. Twenty-three (30.7 %) patients with subglottic laryngeal and upper tracheal stenosis underwent cricotracheal resection and thyrotracheal anastomosis (group A), while 52 (69.3 %) patients with tracheal stenosis underwent tracheal resection and cricotracheal or tracheotracheal anastomosis (group B). The length of the resected segment in patients of groups A and B was 28-55 (42 ± 11) mm and 18-65 (36 ± 14) mm, respectively, (p = 0.22). Perioperative complications within 30 days occurred in eight (34.8 %) patients of group A, and in six (11.5 %) patients of group B (p = 0.04). There was one intraoperative and one postoperative death on the third day due to heart failure. The excellent results were achieved in 63 (86.3 %), satisfactory in 8 (11.0 %), and unsatisfactory in 2 (2.7 %) patients. The incidence rate of perioperative complications is related to the location of the stenosis and the type of the resection and anastomosis. Video mediastinoscopy simplifies the mobilization of the mediastinal trachea, which allows for carrying out the anastomosis with minimal tension. Early internal abnormalities of the anastomosis predict its restenosis.

Diversity and properties of connexin gap junction channels.

Gap junction channels are composed of two apposing hemichannels (connexons) in the contiguous cells and provide a direct pathway for electrical and metabolic signaling between adjacent cells. The family of connexin genes comprises 20 members in the mouse and 21 genes in the human genome. Connexins are expressed in all tissues except differentiated skeletal muscle, erythrocytes, and mature sperm cells. Various tissues express more than one type of connexins; therefore, homotypic, heterotypic, and heteromeric gap junction channels may form between cells. In this article, we briefly review basic gating and permeability properties of homotypic and heterotypic gap junction channels as well as recent achievements in the research of their regulation by transjunctional voltage, intracellular calcium, pH, and phosphorylation.

The conditional connexin43G138R mouse mutant represents a new model of hereditary oculodentodigital dysplasia in humans.

Oculodentodigital dysplasia (ODDD) is a dominant negatively inherited disorder with variable but characteristic anomalies of the fingers and toes, eyes, face and teeth, which are caused by mutations in the connexin 43 (Cx43) gene. All mutations analyzed so far have a negative influence on the conductance through gap junctional channels and hemichannels, as well as trafficking of Cx43 protein in transfected cells. In this study, we inserted the human Cx43G138R point mutation into the mouse Cx43 gene and generated mice conditionally expressing this mutation. All ODDD phenotypic manifestations observed in humans, including syndactyly and enamel hypoplasia as well as craniofacial, bone and heart anomalies, were also observed with significant penetrance in Cx43G138R mice. When this mutation was specifically expressed in cardiomyocytes, characteristic alterations in the electrocardiogram and spontaneous arrhythmias were recorded. In vitro studies with Cx43G138R-expressing cells revealed loss of the Cx43 P2 phosphorylation state, which was also absent in the mutated hearts. This loss has previously been associated with gap junctional dysfunction and increased cellular ATP release. The Cx43G138R mutated mice show significantly increased arrhythmogeneity ex vivo in Langendorff experiments with explanted hearts and in vivo in particular under hypoxic conditions. Our results suggest that the increased activity of ATP-releasing channels in Cx43G138R mutated cardiomyocytes may further reduce the already decreased gap junctional communication and thus aggravate arrhythmogenesis in the mouse mutant.

Permeability of homotypic and heterotypic gap junction channels formed of cardiac connexins mCx30.2, Cx40, Cx43, and Cx45.

We examined the permeabilities of homotypic and heterotypic gap junction (GJ) channels formed of rodent connexins (Cx) 30.2, 40, 43, and 45, which are expressed in the heart and other tissues, using fluorescent dyes differing in net charge and molecular mass. Combining fluorescent imaging and electrophysiological recordings in the same cell pairs, we evaluated the single-channel permeability (P(gamma)). All homotypic channels were permeable to the anionic monovalent dye Alexa Fluor-350 (AF(350)), but mCx30.2 channels exhibited a significantly lower P(gamma) than the others. The anionic divalent dye Lucifer yellow (LY) remained permeant in Cx40, Cx43, and Cx45 channels, but transfer through mCx30.2 channels was not detected. Heterotypic channels generally exhibited P(gamma) values that were intermediate to the corresponding homotypic channels. P(gamma) values of mCx30.2/Cx40, mCx30.2/Cx43, or mCx30.2/Cx45 heterotypic channels for AF(350) were similar and approximately twofold higher than P(gamma) values of mCx30.2 homotypic channels. Permeabilities for cationic dyes were assessed only qualitatively because of their binding to nucleic acids. All homotypic and heterotypic channel configurations were permeable to ethidium bromide and 4,6-diamidino-2-phenylindole. Permeability for propidium iodide was limited only for GJ channels that contain at least one mCx30.2 hemichannel. In summary, we have demonstrated that Cx40, Cx43, and Cx45 are permeant to all examined cationic and anionic dyes, whereas mCx30.2 demonstrates permeation restrictions for molecules with molecular mass over approximately 400 Da. The ratio of single-channel conductance to permeability for AF(350) was approximately 40- to 170-fold higher for mCx30.2 than for Cx40, Cx43, and Cx45, suggesting that mCx30.2 GJs are notably more adapted to perform electrical rather than metabolic cell-cell communication.

Gating properties of heterotypic gap junction channels formed of connexins 40, 43, and 45.

Connexins (Cxs) 40, 43, and 45 are expressed in many different tissues, but most abundantly in the heart, blood vessels, and the nervous system. We examined formation and gating properties of heterotypic gap junction (GJ) channels assembled between cells expressing wild-type Cx40, Cx43, or Cx45 and their fusion forms tagged with color variants of green fluorescent protein. We show that these Cxs, with exception of Cxs 40 and 43, are compatible to form functional heterotypic GJ channels. Cx40 and Cx43 hemichannels are unable or effectively impaired in their ability to dock and/or assemble into junctional plaques. When cells expressing Cx45 contacted those expressing Cx40 or Cx43 they readily formed junctional plaques with cell-cell coupling characterized by asymmetric junctional conductance dependence on transjunctional voltage, V(j). Cx40/Cx45 heterotypic GJ channels preferentially exhibit V(j)-dependent gating transitions between open and residual states with a conductance of approximately 42 pS; transitions between fully open and closed states with conductance of approximately 52 pS in magnitude occur at substantially lower ( approximately 10-fold) frequency. Cx40/Cx45 junctions demonstrate electrical signal transfer asymmetry that can be modulated between unidirectional and bidirectional by small changes in the difference between holding potentials of the coupled cells. Furthermore, both fast and slow gating mechanisms of Cx40 exhibit a negative gating polarity.