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Back to Annual Meeting Program
TUESDAY MORNING, APRIL 27, 2004
7:00 a.m. CARDIAC SURGERY FORUM SESSION
(5 minutes presentation, 7 minutes discussion) North Bldg., Rm 206C, Metro Toronto Convention Centre Moderators: W. Randolph Chitwood, Jr. Pedro J. del Nido
F1. Preliminary Results of Fetal Cardiac Bypass Using Non-human Primates Akio Ikai*, R. Kirk Riemer*, Chandra Ramamoorthy*, Frank L. Hanley, V. Mohan Reddy; Stanford, CA
OBJECTIVE: Fetal cardiac surgery has potential benefits for treatment of some congenital heart defects. We have already established successful implementation of cardiac bypass in the ovine fetus, however, the presence of fetal stress induced by cardiac bypass resulted in placental dysfunction. In this study, we evaluated the technical feasibility of cardiac bypass in the fetal baboon to advance to human surgical intervention and evaluate the efficacy of different anesthetic approaches in reducing fetal stress.
METHODS: A total of twelve baboon fetuses, average gestation 142±8 days and weight 736±185 grams, were used. Three fetuses were excluded from the study because of nuchal cord presentations. The animals were separated into two anesthesia groups: fentanyl/midazolam anesthesia (n=3), and Isoflurane anesthesia (n=6). All fetuses were placed on a miniature conventional roller pump circuit (priming volume <20 ml) without oxygenator for 30 minutes and returned to normal fetal circulation for an hour. No blood transfusion was performed. Blood gas samples for evaluating placental dysfunction and fetal stress were collected pre-bypass, and 15, 30, and 60 min- post-bypass.
RESULTS: All fetuses were successfully placed on the cardiac bypass circuit. All maternal baboons survived. Five of six fetuses in Isoflurane group survived for 60 minutes, whereas all three fetuses in fentanyl group did not survive for 60 min post-bypass. However, placental dysfunction resulting in the decline of blood gas was not prevented in either anesthetic group. (Pa02 pre-bypass, post 15 min, and post 60 min: Isoflurane 33±3, 23±6, and 18±9 mmHg, fentanyl; 21±9, and 17±6 mmHg). Maternal baboons exhibited an extremely high tolerance to fentanyl compared with normal human subjects and uterine tone was sustained with fentanyl anesthesia compared with Isoflurane anesthesia
CONCLUSIONS: The technical feasibility of cardiac bypass in non-human primate fetus, even with extremely low body weight, including no maternal mortality, was confirmed. Isoflurene anesthesia appears to be superior to Fentanyl anesthesia with better uterine relaxation and better fetal-placental gas exchange.
*By Invitation F2. Tissue Oxygenation Index is a Useful Monitor of Histological and Neurological Outcome after Cardiopulmonary Bypass in Piglets Ikuo Hagino*, Vesa Anttila*, David Zurakowski*, Hart G. W. Lidov*, Richard A. Jonas; Boston, MA
OBJECTIVE: Tissue oxygenation index (TOI) is a novel monitoring function derived from near infrared spectroscopy (NIRS). Measurement over three path lengths allows calculation of an absolute value in contrast to percent change from baseline as for previous NIRS monitoring functions. We hypothesized that TOI could predict a minimum safe flow rate for specific bypass conditions.
METHODS: Thirty-six piglets (43 ± 5 days, 9.0 ± 1.1 kg) underwent CPB with cerebral NIRS (NIRO-300). Animals were cooled for 40 min to 15, 25, or 34°C (pH-stat, Hct 20 or 30%, pump flow 100 ml/min/kg), followed by 120 minutes of low flow perfusion (10, 25, or 50 ml/ mm/kg). Neurological deficit score (NDS) and behavioral evaluations were performed daily for 4 days. The brain was then fixed for histological assessment. Analysis employed repeated-measures ANOVA and logistic regression.
RESULTS: During low flow bypass, average TOI, minimum TOI and TOI at 15 minutes after the beginning of low flow were highly correlated (all Spearman rho = 0.98, p<0.001). Animals with TOI greater than 60% had no histological or functional evidence of cerebral injury while all animals with TOI less than 55% had evidence of injury. An inverse correlation was found between average TOI during low flow and NDS on first postop day (Spearman rho = -0.55, p<0.01). Temperature (p<0.001), flow rate (p<0.001), and hematocrit (p=0.02) were significant multi-variable predictors of TOI based on logistic regression using a cutoff of < 55% for TOI.
CONCLUSIONS: TOI is a useful monitor of cerebral oxygenation during CPB and can therefore be used to define the safety and adequacy of perfusion by CPB. Minimum safe flow rate is influenced by hematocrit as well as temperature.
*By Invitation F3. Identification of a Set of Genes that Enable Clustering of Individuals with Bicuspid and Tricuspid Aortic Valves into Separate Groups Marineh Yagubyan*, Thoralf M. Sundt HI, Mark E. Bolander*, Gobiada Sarkar*, Alok Srivastava*, Jay W. Ellison*, Kenton J. Zehr*, Joseph A. Dearani, Richard C. Daly, Thomas A. Orszulak, Charles J. Mullany, Hartzell V. Schaff; Rochester, MN
OBJECTIVE: Patients with bicuspid aortic valves (BAY) have an increased risk of ascending aortic dissection and aneurysm compared to those with tricuspid aortic valves (TAV). Identification of the genes responsible for BAY may provide insights into this phenomenon. Pursuant to this end, we have applied genomic technologies including gene expression arrays and bioinformatics analysis software to investigate clinical specimens of ascending aorta.
METHODS: Total RNA was extracted from ascending aortic tissue of 11 patients (4 BAY with aneurysm, 1 BAY without aneurysm, 3 TAV with aneurysms and 3 TAV without aneurysm) undergoing cardiac operations and subjected to in-situ micro array hybridization to 22,283 probe sets of the Affymetrix® Ul33A DNA chips. After normalization and data filtering, patients were grouped according to gene expression patterns using unsupervised hierarchical clustering (dChip software). The method of nearest centroid analysis was applied to the results of the clustering procedure. A summary of genes whose expression pattern best contributed to the classification of patients into the different dusters was determined using PAM (Prediction Analysis for Micro arrays, Stanford University Labs) software. The latter analysis was performed at a threshold choice of 3.5. The findings were examined in the light of clinical phenotype.
RESULTS: The hierarchical cluster analysis grouped the patients into 2 major clusters and multiple minor clusters as illustrated by the dendrogram (figure). There was apparent correlation between the major clusters (1 & 2) and valve morphology (BAV vs. TAV) but not other patient characteristics, including age, gender, presence or absence of aneurysm, functional pathology or hypertension. Nearest centroid analysis identified a set of 45 genes out of 22,283 (0.2%) that were responsible for the clustering pattern of the 11 samples.
CONCLUSIONS: These results demonstrate two basic gene expression profiles in the ascending aorta, one characteristic of patients with BAV, and the other of those with TAV. This suggests that the biological abnormality responsible for BAV is manifested in the aorta as well as the valve. Investigation of the set of genes responsible for such a classification of the studied patients as well as gene expression analysis of additional patients is in progress.
*By Invitation F4. Surgical Treatment of Ischemic Mitral Regurgitation Will Not Influence Infarction Induced Ventricular Remodeling Sina L. Moainie*, Joseph H. Gorman III*, Yoshiharu Enomoto*, Benjamin M. Jackson*, Theodore Plappert*, Martin G. St. john-Sutton*, Robert C. Gorman; Philadelphia, PA
OBJECTIVE: Surgical treatment for ischemic mitral regurgitation (IMR) has become more aggressive. However, no clinical study has conclusively demonstrated that the surgical correction of IMR improves survival beyond that expected from medical management and revascularization. We used four well-developed ovine models of post infarction left ventricular (LV) remodeling to test the hypothesis that IMR does not significantly contribute to post infarction LV remodeling.
METHODS: Infarction of 21% to 24% of the LV mass was induced by coronary ligation in 77 sheep. Infarctions varied only by anatomic location in the LV: anteroapical (AA), n=26; anterobasal (AB), n=16; laterobasal (LB), n=9 and posterobasal (PB) n=20. Six additional sheep had ring annuloplasty prior to PB infarction. End systolic volume (ESV), end diastolic volume, end systolic muscle to cavity area ratio (ESMCAR), LV sphericity, ejection fraction (EF) and degree of IMR as determined by quantitative echocardiography were assessed before infarction and at 2, 5 and 8 weeks after infarction to evaluate the extent of LV remodeling.
RESULTS: All infarcts resulted in significant post infarction remodeling and decreased EF (table). AA infarcts lead to LV aneurysms and resulted in more severe remodeling than the three other infarct locations. Only PB infarcts caused severe and progressive IMR. Remodeling due to PB infarcts was not more severe than that caused by infarcts at other locations. Furthermore, prophylactic annuloplasty prevented the development of MR after PB infarction but had no effect on remodeling.
*ESV significantly greater for AA infarcts than all other infarct locations at 8 wks ** IMR significantly greater for PB infarcts than all other infarct locations at 8 wks
CONCLUSIONS: The extent of post infarction remodeling is determined by infarct size and location. The development of IMR does not contribute to adverse remodeling. IMR is a manifestation rather than a cause of post infarction remodeling. The current aggressive surgical approach to IMR should be reassessed.
*By Invitation F5. Optimal Temperature for Selective Cerebral Perfusion Justus T. Strauch*, David Spielvogel*, Alexander Lauten*, Ning Zhang*, Sindy Rinke*, Donald Weisz*, Carol A. Bodian*, Randall B. Griepp; New York, NY
OBJECTIVE: Although combinations of hypothermic circulatory arrest (HCA) and ante grade selective cerebral perfusion (SCP) are widely utilized for cerebral protection during aortic arch surgery, there is no consensus regarding optimal temperature during SCP. This study explored the impact of different temperatures during SCP on cerebral metabolism and neurologic outcome.
METHODS: In this blinded study, 40 pigs (20-22 kg) were randomized into 4 groups after 30 minutes of HCA at 20°C. During a subsequent 60-minute interval of SCP, with flow regulated to maintain a perfusion pressure of 50 mm Hg, pigs were per fused at 10°C, 15°C, 20°C and 25°C. Fluorescent micro spheres enabled calculation of cerebral blood flow (CBF) during perfusion and recovery. Hemodynamics, intracranial pressure (ICP), cerebrovascular resistance (CVR), and oxygen consumption (CMR02) were also monitored. Behavioral scores (in which 12 is normal and 0 indicates coma or death) were obtained for 7 days postoperatively.
RESULTS: CBF decreased significantly (p<0.002) during cooling in all groups: it was significantly higher throughout SCP in the 20-25°C vs the 10-15°C groups (p=0.0001), and remained higher during recovery (p=0.0001). As seen below, CMR02 fell significantly with cooling (p=0.0001), remained low during perfusion, and rebounded with rewarming, but was significantly lower with 10-15°C than with 20-25°C throughout SCP (p=0.003), and after CPB was discontinued (p=0.001). Postoperative behavioral scores, also shown below, were significantly higher following SCP at 10-15°C than at 20-25°C, (p = 0.001).
CONCLUSIONS: This study suggests that SCP at 10-15°C provides better global cerebral protection than SCP at 20-25°C, even though CMR02 remains low for several hours after SCP at 10-15°C. Prompt return of metabolism to baseline levels after HCA/ SCP does not necessarily predict superior behavioral outcome.
*By Invitation F6. Systemic Delivery is Superior to Regional Retrograde Perftision of an Adenosine Analogue for Attenuating Injury and Inflammation, and for Cytoarchitecture Preservation After Spinal Cord Ischemia-Reperfusion T. Brett Reece*, Curtis G. Tribble, David O. Okonkwo*, Patrick S. Warren*, Peter I. Ellman*, Randall Woodford*, Joel Linden*, Irving L. Kron, John A. Kern; Charlottesville, VA
OBJECTIVE: Spinal cord (s.c.) injury is a devastating complication of thoracic aortic surgery. Systemic therapy with a selective adenosine AM agonist, ATL-146e, during reperfusion attenuates ischemic s.c. injury. In theory, retrograde regional delivery has the advantage of more potent local effects. We hypothesized that not only does retrograde venous perfusion of ATL-46e reach the s.c. parenchyma, but when compared to systemic therapy it produces superior preservation of function and cytoarchitecture( histology and microtubule associated protein-2 or MAP-2), while reducing neutrophil sequestration.
METHODS: Thirty-five pigs underwent s.c. ischemia with reperfusion by 30min thoracic aortic cross-clamping. Pigs received: retrograde saline (control); retrograde ATL-l46e (GroupII); systemic ATL-146e (GroupIII); systemic ATI-146e+retrograde saline (GroupIV); or systemic ATI-146e+retrograde ATI-146e (GroupV). Retrograde therapies were via accessory hemiazygous vein during ischemia. Systemic ATL-146e (0.06mg/kg/min) was given intravenously for 3h beginning 10min before reperfusion. At 24h, motor function was assessed (Tarlov scores: 0 paralyzed-5 normal gait). Tissue was analyzed for neuronal viability, MAP-2 immunostaining, and neutrophil sequestration (myeloperoxidase activityor MPO, DOD/mg/min).
RESULTS: Two pigs received retrograde barium prefusion showing both radiographic and histologic spinal cord perfusion. Tarlov Scores at 24h were significantly improved vs. control in Groups II, III, IV (control: 1.33±0.8; GroupII: 5.00±0.00; GroupIII: 4.83±0.17; GroupIV: 5.00±0.00; p<0.05). Neuronal viability (viable neurons/hpf) was significantly preserved compared to controls in all systemic ATI groups (control:7.20±0.47; GroupIII: 8.52±0.46; GroupIV: 9.27±0.58; p<0.05). MAP-2 immunoreactivity in gray matter was likewise significantly preserved vs. controls in all systemic ATL groups (control: 16.49±1.71%; GroupIII: 34.80±2.04%; GroupIV: 39.78±2.26%; GroupV: 29.87±1.65%; p<0.003). Systemic ATL administration significantly lowered MPO activity versus controls (control: 7.20±0.47; GroupIII: 8.52±0.46; GroupIV: 9.27±0.58; GroupV: 6.69±0.51; p<0.01).
CONCLUSIONS: Although retrograde perfusion of ATL-146e delivers drug to the spinal cord, systemic therapy provides significantly better preservation of function and neuronal cytoarchitecture, while limiting s.c. neutrophil sequestration. The attenuation of ischemic spinal cord injury by ATL-146e is optimal with systemic therapy, possibly through enhanced treatment of systemic inflammatory cells usually absent in spinal tissue.
*By Invitation F7. Early Ischemic Preconditioning Is Superior To Late Ischemic Preconditioning In Spinal Cord Protection After Descending Thoracic Aortic Occlusion Ioannis K. Toumpoulis*, John C. Papakostas*, Miltiadis I. Matsagas*, Vassiliki D. Malamou-Mitsi*, Lina S. Pappa*, Constantine E. Anagnostopoulos; loannina, Greece, New York, NY
OBJECTIVE: We previously showed that both early and late ischemic preconditioning (IPC) significantly reduced spinal cord injury caused by 35-minute descending thoracic aortic occlusion (DTAO) in a porcine experimental model. In this study we investigated the effect of IPC on ischemic spinal cord injury after 45-minute DTAO.
METHODS: Thirty-two pigs (28 to 32 kg) were divided into five groups: group 1 (n=6) underwent a sham operation, group 2 (n=6) underwent DTAO for 20 minutes, group 3 (n=6) underwent DTAO for 45 minutes, all without IPC. Group 4 (n=6) underwent DTAO for 20 minutes and 48 hours later DTAO for 45 minutes (late IPC) and group 5 (n=8) underwent DTAO for 20 minutes and 80 minutes later DTAO for 45 minutes (early IPC). DTAO was accomplished by using 2 balloon occlusion catheters placed Duoroscopically beyond the origin of the left subclavian artery and at the aortic bifurcation. Neurologic evaluation was performed by an independent observer according to Tarlov's score (0-4, 4=normal). The lower thoracic and lumbar spinal cords were harvested at 120 hours and examined histologically with hematoxylin-and-eosin stain. The number of neurons was counted and the grade of inflammation was scored (0-4, 4=no inflammation). Results were expressed as the mean ± standard deviation and statistical analysis was by means of the Kruskal-Wallis (Tarlov score and grade of inflammation) and 1-Way ANOVA test (number of neurons).
RESULTS: Results are summarized in table. Group 5 (early IPC) had better Tarlov score by comparison to group 3 (control, no IPC; P=0.001) as well as to group 4 (late IPC; P=0.001).The histologic changes were propotional to the Tarlov scores, with the least histologic damage in the animals of group 5 as compared to group 3 (number of neurons, P<0.001 and grade of inflammation, P=0.004) or group 4 (number of neurons, P<0.001 and grade of inflammation, P=0.006).
CONCLUSIONS: Early IPC is superior to late IPC in reducing spinal cord injury even after the extreme ischemia of 45 minutes DTAO. This was confirmed by Tarlov score and histopathology.
*By Invitation F8. Cardioprotective Stress Response in the Human Fetal Heart John G. Coles, Mark Takahashi*, Diane Grant*, Xiaojing Dai*, Changqing Du*, Cathy Boscarino*, Gregory Hannigan*; Toronto, ON, Canada
OBJECTIVE: We propose that the fetal heart is highly resilient to hypoxic stress, on the basis of a robust stress-inducible gene repertoire. Our objective was to elucidate the human fetal gene expression profile in response ischemia/ reperfusion (I/R), in order to identify targets which confer innate cardio protection.
METHODS: Primary cultures of human fetal cardiac myocytes (HFCM) (gestational age 15-20 weeks) were exposed to simulated I/R in vitro using ischemic buffer and anoxic conditions. Total RNA from treated and baseline cells were isolated, reverse transcribed, and labeled with Cy3 or Cy5, and hybridized to a human cDNA micro array. Significance of changes in sequential gene expression was determined by repeated permutation of MIAME-compliant data using Significance Analysis for Micro array (SAM). Results from the SAM analysis were visualized as hierarchical clusters and significant (false discovery rate < 3%) genes classified by their differential response to ischemia and/or reperfusion. Post-translational changes in the protein kinase B (PKB) signaling pathway was determined based on phosphorylation of PKB, mitogenactivated protein kinase (MAPK), and glycogen synthase kinase-3β (GSK-3 β).
RESULTS: HFCM exhibited no detectable apoptosis induction after 4 hr I with or without R, in comparison to >3-fold increase over baseline in neonatal rat CM, as measured in situ using TUNEL or Hoechst staining (p<0.05). Hierarchical gene-wise clustering revealed 4 temporally distinct expression strata: A: Repression during I and R; B: Repression during I; C: Activation during I and/or R; and D: Activation during I; repression during R. The fetal response included suppression of IL-6, MAPK, and the zinc finger transcription factor, ERF-1, implying a transcriptional response dominated by anti-inflammatory and anti-proliferative properties during I and R. This prediction is supported by rapid (de-activating) de-phosphorylation of PKB and MAPK, and a concordant (activating) de-phosphorylation of GSK-3β.
CONCLUSIONS: HFCM exposed to I/R exhibit a uniquely adaptive transcriptional response. The "fetal" response includes a limited number of functional clusters dominated by predicted anti-inflammatory properties. The de-induction of the MAPK and PKB signaling cascade in HFCM may serve the energetically beneficial purpose of dampening agonist-induced, pro-inflammatory and pro-proliferative signaling during I/R. The stress-inducible fetal CM gene repertoire is a useful platform for identification of targets relevant to the mitigation of cardiac ischemic injury, and highlights a novel mechanism of action (IL-6 transcription blockade) for preventing cardiac myocyte injury associated with ischemia and reperfusion.
*By Invitation F9. Aprotinin Decreases Ischemic Damage During Coronary Revascularization Harold L. Lazar, Yusheng Bao*, Leslie Tanzillo*, Paul O'Gara*, Deborah Reardon*, David Price*, Richard Crowley*; Boston, MA
OBJECTIVE: Aprotinin decreases blood loss and limits the use of blood products during cardiac surgery. Aprotinin may also limit the inflammatory response during cardiopulmonary bypass. This study sought to determine whether the favorable anti-inflammatory effects of aprotinin might limit ischemic damage during the revascularization of ischemic myocardium.
METHODS: Twenty pigs underwent 90 minutes of coronary occlusion followed by 45 minutes of blood cardioplegic arrest and 180 minutes of reperfusion. Ten animals received a loading dose of aprotinin (40,000 IU/kg) during the start of coronary occlusion followed by an infusion of 20,000 IU/kg/hour. Ten animals received no aprotinin. Parameters assessed included the incidence of cardio versions for ventricular arrhythmias, the percent (%) increase of lung water (H2O), endothelial function using % coronary artery relaxation to bradykinin, and infarct size using Area Necrosis/Area Risk (AN/AR).
RESULTS: All values represent the mean+/_ standard error.
CONCLUSIONS: Aprotinin limits ischemic injury during acute coronary revascularization by decreasing ventricular arrhythmias and lung edema, preserving endothelial coronary function, and minimizing myocardial necrosis.
*By Invitation F10. Normalization of Coronary Micro vascular Reactivity and Improvement in Myocardial Perfusion by Surgical VEGF Therapy Combined With Oral Supplementation of L-Arginine in a Porcine Model of Endothelial Dysfunction Pierre Voisine*, Cesario Bianchi*, Tanveer A. Khan*, Marc Ruel*, Shu-Hua Xu*, Jun Feng*, Jianyi Li*, Tamer Malik*, Audrey Rosinberg, Frank W. Sellke; Boston, MA, Ottawa, ON, Canada
OBJECTIVE: The angiogenic effects of VEGF are mediated in part through NO release, whose availability is decreased in endothelial dysfunction associated with advanced coronary artery disease. This is a possible explanation for the poor results of VEGF therapy in clinical trials compared to animal models. We sought to evaluate the influence of L-arginine supplementation to VEGF therapy on coronary micro vascular reactivity and myocardial perfusion in a porcine model of endothelial dysfunction.
METHODS: Twenty-four pigs were fed either a normal (NORM, n=8) or high cholesterol diet, with (CHOL-ARG, n=8) or without (CHOL, n=8) L-arginine. All pigs underwent ameroid placement on the circumflex artery, then were randomized 3 weeks later to receive surgical VEGF-or placebo- treatment (n=4 each per diet group) in the ischemic territory. Four weeks post-treatment, endothelial-dependent coronary micro vascular responses to ADP, FGF-2 and VEGF were assessed by video microscopy. Lateral myocardial perfusion was quantified by isotope-labeled micro spheres at baseline and after treatment. VEGF and eNOS protein levels were determined by Western blotting.
RESULTS: Pigs from the 3 placebo groups showed endothelial dysfunction in the circumflex territory, with decreased micro vascular relaxation to ADP (all p<0.05 vs non-ischemic LAD territory). VEGF therapy normalized the endothelial-dependent relaxation to ADP in both the NORM and the CHOL-ARG groups, but not in the CHOL group. VEGF treatment also improved myocardial perfusion in the NORM group (Post- vs pre-treatment ratios of lateral/anterior wall blood flow were 0.77 (placebo) and 1.38 (VEGF), p= 0.002) but was ineffective in the CHOL group (ratios 0.71 (placebo) vs 0.80 (VEGF), p=NS). Addition of L-arginine to VEGF resulted in restoration of its angiogenic effect despite the high cholesterol diet (ratios 1.08 (placebo) vs 1.25 (VEGF) for CHOL-ARG group, p=0.01). L-arginine treatment was also associated with an increase in both VEGF and eNOS protein levels in the ischemic territory, in contrast to the 2 other diet groups where both were decreased.
CONCLUSIONS: Hypercholesterolemia-induced endothelial dysfunction results in resistance to the effects of exogenous VEGF on coronary micro vascular reactivity and angiogenesis in a swine model of chronic myocardial ischemia. L-arginine supplementation can restore the normal response to endothelium-dependentvasorelaxants as well as the angiogenic response to VEGF treatment, and is associated with increased expression of VEGF and eNOS. These findings suggest a putative role for L-arginine in combination with VEGF therapy for end-stage coronary disease.
*By Invitation TUESDAY MORNING, APRIL 27, 2004
7:00 a.m. GENERAL THORACIC FORUM SESSION (5 minutes presentation, 7 minutes discussion) North Bldg., Rm 206D, Metro Toronto Convention CentreModerators: 1Yolanda Colson* Thomas A. D'Amico
F11. Experimental Generation of a Tissue Engineered Functional and Vascularized Trachea Thorsten Walks*, Heike Mertsching*, Bettina Giere*, Paolo Macchiarinl*, Hannover, Germany
OBJECTIVE: To establish methods to grow smooth muscle cells (SMC), chondrocytes (CC) and respiratory epithelium (RE) on a vascularized biological matrix (BioVaM) as a scaffold for tracheal tissue engineering.
METHODS: We obtained tracheal, costal and auricular cartilage, SMC, RE and endothelial progenitor cells (EPC) from porcine donor animals (n= 10). SMC were cultured in vitro till the 3rd passage and disseminated on a tubular a cellular biological scaffold with a preserved capillary system (BioVaM). CCs were cultured in brooch shape on the BioVaM. The luminal surface was cultured with RE. We applied HE and azan staining to determine tissue formation. Life-dead and MTT assay to determine cell viability and proliferation. Quantitative western blots and immunhistochemical methods served as protein chemical markers of cellular differentiation and function.
RESULTS: Autologous reendothelialization of the BioVaM with EPC resulted in a vascularized scaffold. SMC seeding resulted in muscular tube formation. The fibrillating RE showed a viability of >80% and was successfully cultured on the luminal surface. CC grew encapsulated solitary in lacunas producing extra cellular cartilaginous matrix already after 2 weeks in culture. Life-Dead staining and MTT assay documented viability and proliferation in vitro. Rib and tracheal CC showed a similar growth pattern. Amplified collagen production paralleled high cellular viability and proliferation.
CONCLUSIONS: For the first time we generated and combined all tissues required for a functional bioartificial tracheal graft. The BioVaM offers an extra cellular matrix composition that facilitates i)functional respiratory epithelialization, ii)growth of viable and functional chondrocytes iii)co-cultivation of chondrocytes with muscle cells and leads to viable tracheobronchial grafts. Clinical applicability has to be tested in a large animal model.
*By Invitation 12002-04 Research Scholar F12. Cisplatin-mediated Enhancement of Cytotoxicity of Tumor-selective Adenovirus expressing GFP-TRAIL (Green Fluorescence Protein-TNF-Related Apoptosis Inducing Ligand) Fusion Protein in Cultured Cancer Cells of the Lung, Esophagus, and Pleura Rishindra M. Reddy*, Justin B. Maxhimer*, George W. Cole, Jr.*, Alexander Chua*, Binglang Fang*, David S. Schrump, Dao M. Nguyen*; Bethesda, MD, Houston, TX
OBJECTIVE: Cancer cells frequently exhibit resistance to TRAIL cytotoxicity despite the expression of functional receptors (DR4/DR5). Pretreatment of TRAIL-refractory cells with cisplatin (CDDP) sensitizes them to this ligand. TRAIL can be delivered to cancer cells either as soluble protein or via adenoviral vectors. Moreover, it is well recognized that CDDP enhances adenoviral transgene expression. This study aims to evaluate: 1/ cytotoxic potency of the tumor-specific adenoviral vector expressing the GFP/TRAIL fusion protein driven by the human telomerase reverse transcriptase promoter (Ad/gTRAIL) and 2/the ability of CDDP to enhance the cytotoxic effect of this novel adenoviral vector in cultured lung (NSCLC), esophageal (EsC) and malignant pleural mesothelioma (MPM) cancer cells.
METHODS: NSCLC ( H322), EsC (TE2, TE12) and MPM (H513, H2373, H28) cells and primary normal cells (human endothelial cells and fibroblasts) were infected with Ad/gTRAIL or control vector Ad/GFP at MOI of 3 - 60 pfu/cell with or without CDDP (0.5 to 2 _g/ml x 24hrs) pretreatment. Adenoviral transgene expression was determined by GFP fluorescence intensity using flow cytometry. Treatment-mediated cytotoxicity was measured by MTT assays and DNA fragmentation EL1SA kits. Ad/gTRAIL IC50 values were estimated from dose-response curves.
RESULTS: GFP-TRAIL fusion protein expression was detected in cancer cells but not normal cells. CDDP enhanced GFP-TRAIL fusion protein expression by 2- to 12-fold. While Ad/gTRAIL induced mild cytotoxicity (IC50 values > 500 pfu/cell), CDDP pretreatment resulted in dose-dependent enhancement of Ad/gTRAIL-mediated cytotoxicity as indicated by drastic reduction of Ad/gTRAIL IC50 values in all cancer cell lines (4 ± 0.1 to 42 ± 1.7 phi/cell, n=4). CDDP + Ad/gTRAIL combination mediated a 8- to 14-fold increase of DNA fragmentation (versus <5-fold in cells treated with CDDP or Ad/gTRAIL alone). There was no cytotoxicity mediated by the Ad/GFP control vector on cancer cells, nor was there cytotoxicity in normal cells treated with the CDDP + Ad/gTRAIL combinations.
CONCLUSIONS: CDDP pretreatment enhances Ad/gTRAIL cytotoxicity in malignant but not normal cells. The mechanisms underlying this salutary effect may involve both enhancement of the susceptibility of CDDP-treated cells to TRAIL as well as CDDP-mediated enhancement of TRAIL expression in Ad/gTRAIL infected cells. These findings provide rationale for development of Ad/gTRAIL-based therapy for thoracic malignancies.
*By Invitation F13. Proteasome Inhibition Sensitizes Non-Small Cell Lung Cancer to Histone Deacetylase Inhibitor-Induced Apoptosis Through the Generation of Reactive Oxygen Species Chadrick E. Denlinger*, Brian K. Rundall*, David R. Jones*; Charlottesville, VA
OBJECTIVE: Non-small cell lung cancer (NSCLC) remains resistant to both traditional and novel forms of chemotherapy including histone deacetylase (HDAC) inhibitors. The HDAC inhibitor, SAHA induces apoptosis other malignancies, in part, through the generation of reactive oxygen species (ROS). In NSCLC, HDAC inhibitors potently activate the anti-apoptotic transcription factor NF-KB which is known to protect cells from the ROS generation. Pharmacological proteasome inhibition with Velcade suppresses NF-KB transcriptional activity and sensitizes NSCLC to apoptosis. We hypothesize that proteasomes inhibition will enhance SAHA-induced generation of ROS and induce apoptosis in NSCLC.
METHODS: Four tumorigenic NSCLC cell lines (H157, H358, H460 and A549) were treated with nothing, SAHA (5 μM), Velcade (50 nM) or both SAHA and Velcade. NF-κB transcriptional activity was determined by a 3x-κB-luciferase reporter gene and by transcription of the endogenous gene IL-8. ROS generation was quantified by flow cytometery using the ROS sensitive fluorophore, H2DCFDA. Cell viability was determined following sequential or concomitant treatment by clonogenic assays, and apoptosis determined by a nucleosome ELISA and by activation of caspase-3. Finally, apoptosis assays were repeated in similarly treated cells incubated in the presence or absence of the free radical scavenger, N-acetyl cysteine.
RESULTS: SAHA significantly enhanced 3x-κB-luciferase reporter gene and endogenous IL-8 transcription, and these effects were significantly inhibited by Velcade (p = 0.001). Combined HDAC and proteasome inhibition induced significantly greater ROS generation compared to all other treatments. Concomitant therapy dramatically suppressed clonogenitity relative to single drug or sequential drug administration. Combined treatment with SAHA and Velcade significantly enhanced apoptosis relative to all other treatment groups (p = 0.0003). The free radical scavenger N-acetyl cysteine rescued cell death in NSCLC cells treated with combined therapy (p = 0.004).
CONCLUSIONS: SAHA and Velcade synergistically induce the generation of ROS in NSCLC cells, and this plays a critical role in the induction of tumor apoptosis following treatment. Combined HDAC and proteasome inhibition may be an effective treatment strategy for NSCLC.
*By Invitation F14. Profound Induction of Apoptosis of Lung and Esophageal Cancer Cells by the Histone Deacetylase Inhibitor Trichostatin A/Protein Kinase C Inhibitor Calphostin C Combination Justin B. Maxhimer*, Rishindra M. Reddy*, George W. Cole, Jr.*, David S. Schrump, Dao M. Nguyen*; Bethesda, MD
OBJECTIVE: Histone deacetylase inhibitors (HDACi) are pharmacologic agents with potent antitumor activities which are currently in clinical trials. It is well recognized that HDACi induce profound up regulation of NF-kB transcription and p21 protein levels, both of which have been shown to impede the ability of HDACi to induce apoptosis in cancer cells. Signaling via the protein kinase C (PKC) has been implicated as an upstream event of HDACi-induced p21 and possibly NF-kB modulation. This study aims to determine if pharmacologic inhibition of PKC using Calphostin C (CC) would result in enhancement of apoptosis in nonsmall cell lung cancer (NSCLC) and esophageal cancer (EsC) cells treated with the HDACi, Trichostatin A (TSA).
METHODS: NSCLC (H460, H322) and EsC (TE2, TE12) cells were concurrendy treated with CC (0.1 to 4 μM) and TSA (0.1 to 2 μM). NF-kB transcriptional activity was quantitated by NF-kB-Luciferase assay. Transcription of the p21 gene and p21 protein levels were evaluated by p21 promoter-Luciferase assay and p21 ELISA respectively. Apoptosis was evaluated by the TUNEL-based ApoBrdU assay.
RESULTS: Exposure of NSCLC and EsC cells to TSA (0.1 and 1.0 µM) resulted in dose- and cell-dependent 2- to >20-fold increase of NF-kB as well as p21 transcriptional activity. Concurrent treatment with TSA and CC (1 or 2 μM) led to a 50% to 90% decrease in NF-kB and p21 transcriptional activity. Similarly, TSA-mediated 2- to >20-fold dose-dependant elevation of p21 protein levels was profoundly (60% to > 90%) diminished by CC. Inhibition NF-kB activity by either adenovirally mediated expression of the super repressor IkB or by the pharmacologic inhibitor Parthenolide resulted in significant dose-dependant reduction (30% to >99%) of TSA-mediated up regulation of p21 transcription. This indicates that NF-kB may serve as a major transcriptional regulator of increased p21 expression in TSA-treated cancer cells. Most importandy, while exposure of cultured cancer cells to either CC or TSA alone resulted in <10% cell death, 60% to 95% of NSCLC or EsC cells treated with the CC+TSA combination underwent apoptosis.
CONCLUSIONS: Pharmacologic inhibition of PKC abrogates TSA-mediated up regulation of NF-kB transcriptional activity and p21 expression coinciding with profound induction of apoptosis in NSCLC and EsC cells. PKC may be a novel target for enhancing the efficacy of HDACi in cancer therapy.
*By Invitation F15. Epidermal Growth Factor Is Important to Malignant Mesothelioma Cell Growth and Survival and Mediates Its Effects via the PI3 Kinase Pathway Philip A. Rascoe*, Xiaobo Cao*, Jonathan C. Daniel*, Steven D. Miller*, W. Roy Smythe; Houston, TX
OBJECTIVE: The PI3 kinase (PI3K) pathway is important to cell growth and survival and is deregulated in some malignancies. We have previously shown high levels of the PI3K downstream mediator phosphorylated ART (pAKT) in human malignant mesothelioma (MM) tumor specimens, as well as a decrease in pAKT, MM apoptosis in vitro and reduced tumor burden in vivo with exposure to LY249002, a PI3K inhibitor. It is known that PI3K is recruited by cell surface receptors for peptide growth factors that directly activate cell survival pathways. We sought to determine which receptor reactions play a role in regulating the PI3K pathway in MM and how their overall contribution effects cell survival.
METHODS: The human MM cell lines REN and 1-45 were maintained in culture. Cells were treated with varying doses of receptor inhibitors of epidermal growth factor (EOF - AG1478), platelet derived growth factor (PDGF - AG1295), and insulin-like growth factor (IGF - AG538) with DMSO vehicle as control. At 72 hours following treatment, a cell viability assay (XTT) was performed to determine the survival fraction, and Western blot for pAKT. To assess the effects of EGF on the PI3K-AKT pathway, cells were treated with or without one-hour exposure of IY294002 and then exposed to 10nM of EGF followed by pAKT Western blot analysis at 15,30 and 60 minutes.
RESULTS: The PDGF inhibitor did not influence MM cell viability or pAKT levels. IGF inhibition led to a decrease in cell viability (p<. 01 AG538 vs. DMSO) but did not affect pAKT levels. Only the EGF inhibitor resulted in a combined reduction in pAKT and cell viability in both cell lines (p<. 01 AG1478 vs. DMSO). Following serum starvation, baseline expression of pAKT was negligible. Cells stimulated by EGF showed significant increases in pAKT levels, however, those cells in the presence of LY294002 showed minimal or zero expression.
CONCLUSIONS: In MM,constitutive phosophorylation of AKT results in cell survival and contributes to the malignant phenotype. We have shown that EGF inhibition leads to cell death via down-regulation of pAKT levels in MM cell lines. In addition, EGF can be shown to activate phosphorylation of AKT and likely drives PI3K mediated inhibition in MM. Both PI3K and EGF inhibition in MM may be clinically relevant.
*By Invitation F16. Suppression of Prometastasis Phenotypes Expression in Malignant Pleural Mesothelioma Cells by the Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor PD 153035 George W. Cole, Jr.*, Rishindra M. Reddy*, Justin B. Maxhimer*, Annette Alleva*, David S. Schrump, Dao M. Nguyen*; Bethesda, MD
OBJECTIVE: Malignant pleural mesothelioma (MPM) is notorious for loco-regional recurrence despite aggressive multi-modality therapy. EGFR expression has been observed on MPM cells. EGFR-mediated signaling plays important roles in proliferation and metastasis of cancer cells. At the cellular level, metastasis is a multi step process that involves cell proliferation, angiogenesis, cell motility and invasion through extra cellular matrix. This study aims to evaluate the ability of the EGFR tyrosine kinase inhibitor PD153035 (PD) to modulate the expression of prometastasis phenotypes in MPM cells in vitro.
METHODS: EGFR expression was quantitated by flow cytometry and compared to levels expressed on primary normal cells (skin keratinocytes). Cultured MPM cells were treated with PD (0.5 to 5 _M); cell growth was determined by MTT, VEGF levels in conditioned media were measured by ELJSA, cell motility and invasion of extra cellular matrix were determined by in vitro wound healing and Matrigel invasion assays respectively.
RESULTS: EGFR expression was detected on all 6 cultured MPM cells with 4/6 having normal (< 2-fold) and 2/6 over expressing this receptor (> 4-fold the level of primary keratinocytes). PD inhibited proliferation and VEGF production only in MPM cells expressing high levels of EGFR (H513 and H2595). On the other hand, PD profoundly suppressed motility and invasion through extra cellular matrix of all MPM cells regardless of their EGFR expression status (Table 1; *Mean fluorescence intensity normalized for IgG isotype control; Keratinocytes = 8.** 2.5 microM PD153035 x 4 days; Mean ± SD, n=4. #Semiquantitative analysis of cell motility, 5.0 _M PD vs control media, n=3.## 2.5 _M PD vs control media, n=3;¶ p<0.03,¶¶ p= Non significant, Student's t-test).
CONCLUSIONS: EGFR inhibitor PD 153035 significantly inhibited motility and invasion of MPM cells in vitro. Inhibition of EGFR-dependent signaling may be a useful strategy to diminish MPM recurrence following aggressive cytoreductive therapy.
*By Invitation F17. Facilitating Cell-mediated Alloengraftment is Dependent on an FcεRIγ Signaling Pathway Kendra N. Taylor*, Rahilya Napoli*, Renee Wright*, 1Yolonda L. Colson*; Boston, MA
OBJECTIVE: The facilitating cell (FC) is a bone marrow-derived cell population that promotes allogeneic stem cell (SC) engraftment and donor-specific transplantation across complete MHC-disparities. This function is dependent on the expression of a unique heterodimer on the cell surface of the FC, which consists of the T cell receptor beta chain (TCRβ) and a novel 33kD protein, FCp33. All known TCRβ effect or functions are mediated through a group of related proteins within the CD3ζ family. The two predominant members are CD3ζ, which is utilized by conventional αβTcells for induction of proliferative and cytotoxic responses, and FcεRIγ, which has been shown to play a role in the regulation of T cell and natural killer cell development and differentiation. We hypothesized that the dependence of FC-mediated alloengraftment on TCRβα-FCp33 expression was the result of required TCRβ signaling within the FC. Therefore, the objective of the current study was to identify whether a CD3ζ or FcεRIγ dependent signaling pathway was required for FCp33-mediated alloengraftment in vivo.
METHODS: FC were isolated by flow cytometric cell sorting as CD8+/αβγδTCR-, from donor bone marrow of CD3ζ-/- or FcεRIγ/- C57B1/6 (B6) knock out mice. Lethally irradiated B10.BR recipients were reconstituted with 50,000 FC and 10,000 purified SC obtained as Sca+ ckit+ Lin- from normal B6 mice. Allogeneic SC engraftment was confirmed by flowcytometric peripheral blood lymphocyte typing of donor MHC antigen expression 28 days post-transplant.
RESULTS: Recipients reconstituted with SC and FC either isolated from control B6 or CD3ζ-/- donors survived and exhibited >90% donor chimerism, demonstrating that the FC does not mediate facilitation via CD3ζ signaling. In marked contrast, all recipients reconstituted with SC but with FC from FcεRIγ/- donors (n=9), failed to engraft resulting in a 40-day mortality of 100%.
CONCLUSIONS: This is the first report of a TCRβ-FCp33 receptor-signaling pathway that is critical for FC-mediated alloengraftment in vivo. The dependence of FC function has previously been shown to require TCRβ-FCp33 expression and the current data suggests that the necessary signaling through this receptor is dependent on a non-conventional Tcell signaling pathway that involves FcεRIγ. Approaches to induce tolerance through the FCp33 receptor and /or FcεRIγ signaling offer new direction and insight into alloreactivity and immunomodulation, with the potential to revolutionize clinical organ transplantation in the future.
*By invitation 22002-04 Research Scholar F18. Adenosine A2A Receptor Activation Attenuates Lung Reperfusion Injury Independent of Circulating Leukocytes Victor E. Laubach*, Thomas Maxey*, Joel Linden*, Allan Doctor*, Carlos Tache Leon*, Curtis Tribble, Irving L. Kron; Charlottesville, VA
OBJECTIVE: Reperfusion injury is a major cause of mortality after lung transplantation. Activation of adenosine A2A receptors, found mainly on neutrophils, monocytes, macrophages, platelets, and mast cells, produces anti-inflammatory responses. We have previously shown that A2A receptor activation reduces lung reperfusion injury in a blood-perfused model. In this study, we investigated the effects of an A2A agonist in buffer-perfused lungs to ascertain if tissue protection is still noted in the absence of blood.
METHODS: A model of ischemia-reperfusion injury in a murine, buffer-perfused, isolated lung system (Hugo Sachs Elektronik, Germany) was utilized. Three groups of C57BL6 mice were studied. All lungs underwent 10 min equilibration on the apparatus. Lungs from the Control group underwent 60 min ischemia and hypoxic ventilation followed by 60 min constant flow reperfusion under normoxia. The A2A agonist group (ATL) was identical to Control except that ATL-303, a novel, specific and potent A2A receptor agonist, was included in the perfusate buffer at 100 nM. A Sham group was perfused for 120 min without ischemia. Lung compliance (LC), airway resistance (AR), mean pulmonary artery pressure (PAP) were measured throughout reperfusion and histology was assessed at the end of reperfusion.
RESULTS: The lungs which received ATL-303 displayed significantly increased LC and significantly decreased PAP and AR throughout reperfusion compared to Controls (p<0.001). At the end of reperfusion, LC for ATL (13.2 ± 1.4 ul/cm H2O) was significantly higher than Control (8.3 ± 0.7) (p<0.001). At the end of reperfusion, PAP for ATL (19.3 ± 2.1 cm H2O) was significantly lower than Control (36.8 ± 4.7) (p<0.001). At the end of reperfusion, AR for ATL (1.67 ± 0.25 cmH20(sec)/ul) was significantly lower than Control (3.38 ± 0.43) (p<0.001). In addition, ATL-303-treated lungs displayed reduced evidence of lung injury by histology (see Figure).
CONCLUSIONS: These results suggest that specific activation of A2A receptors improves lung reperfusion injury even in a non-blood perfused system, indicating the importance of resident, parenchymal lung cells such as macrophages and endothelial cells, and not just circulating leukocytes such as neutrophils.
*By Invitation F19. Early Development of Bronchiolitis Obliterans Syndrome After Lung Transplantation is Associated With Bile Acid Aspiration Frank D'Ovidio*, Marco Mura*, Melanie Tsang*, Thomas K. Waddell*, Michael Hutcheon*, Lianne G. Singer*, Andrew Pierre*, Dennis Hadjiliadis*, Ceciha Chaparro*, Carlos Gutierrez*, Gail Darling*, Mingyao Liu*, Shaf Keshavjee; Toronto, ON, Canada
OBJECTIVE: Gastro-esophageal reflux disease with associated aspiration is currently being investigated as a potential contributor to BOS following lung transplantation. We prospectively investigated aspiration by assessing presence of bile acids in surveillance broncho-alveolar lavage fluid (BALF) and determined its role towards development of BOS.
METHODS: Ninety-three consecutive lung transplant patients followed with surveillance PFT, and bronchoscopies were evaluated. Diagnosis of BOS (grade Op-3) was formulated after at least 6-months of follow-up from transplant. Time from transplant to BOS development was defined as early or late whether or not BOS occurred within 12 months of the transplant. BALF samples were collected at each surveillance bronchoscopy and were assayed for differential cell count, bile acids, IL-8 (neutrophil chemokine) and IL-15 (lymphocyte stimulator). The BALF bile acids levels were considered elevated when greater than normal serum levels (= 8 μmol/L). Bile acids were concurrently tested in serum samples from 20 patients collected within 24-hrs of the BAL.
RESULTS: There was no correlation between bile acid levels in serum and BALF. Elevated bile acids were measured in BALF from 19/93 (20%) of patients. BOS was diagnosed in 30/93 (32%) of patients, and judged early in 17/30 (57%). BALF bile acids in BOS pts (median 2 μmol/L, range 0-71) were greater than in non BOS pts (0 μmol/L, range 0-31) (Mann-Whitney test p=0.004). Bile acids in early BOS pts (6.5 μmol/L, range 0-71) were greater than in late BOS pts (0 μmol/L, range 0-8.6) (p=0.006). Bile acids levels in early BOS pts correlated with IL-8 and alveolar neutrophilia (Spearman Rank Correlation, r = 0.4, p = 0.02, and r = 0.6, p = 0.02, respectively) but not with IL-15. No correlation was observed in late BOS pts. The figure shows the actuarial curves relative to freedom from BOS in all patients sub-grouped according to the bile acids levels (Logrank Mantel Cox p=0.0001).
CONCLUSIONS: Duodeno-gastro-esophageal reflux related pulmonary aspiration is highly prevalent in lung transplant patients as evidenced by bile acid detection in the BAL. Furthermore elevated broncho-alveolar bile acids levels promote early development of bronchiolitis obliterans syndrome likely by contributing to an inflammatory process mediated by IL-8 and alveolar neutrophilia. These findings strongly support the role of gastro-esophageal reflux disease within the development of bronchiolitis obliterans syndrome.
*By Invitation F20. Safety and Feasibility of Airway Bypass Stent Placement and Influence of Topical Mitomycin on Stent Patency 1Cliff K. Choong*, Fabio J. Haddad*, Joel D. Cooper; St. Louis, MO
OBJECTIVE: Airway bypass via trans bronchial fenestration has been shown to improve forced expiratory volume and flow in explanted human emphysematous lungs. The aim of this study was to evaluate the feasibility and safety of in vivo airway bypass stent placement using a canine model and to assess the influence of topical mitomycin (MMC), an anti-inflammatory and antifibrotic agent, on prolongation of stent patency.
METHODS: Twelve specially bred research mongrel dogs were utilized for the study. Under general anesthesia, suitable segmental and sub segmental bronchial wall sites were selected by direct visualization using a flexible bronchoscope. The absence of adjacent peribronchial blood vessels was confirmed using a Doppler probe passed through the bronchoscope channel. Trans bronchial fenestrations were formed by puncture with a 22 gauge trans bronchial needle and dilatation of the needle track using a 2.5mm angioplasty balloon. A 3 mm long by 3 mm wide balloon expandable stainless steel stent covered with a sleeve of silicone rubber was placed within the fenestration. Seventy stents were placed in 12 dogs. Animals were bronchoscoped weekly to assess stent patency and for topical MMC application. Control stents were placed in all 12 dogs and were untreated (n=35). Stents treated with MMC (n=35) had topical application of 0.2mls of MMC (concentration 1 mg/ml). All MMC stents were treated at the time of stent placement and subsequently at weekly intervals as shown in Table.
RESULTS: Four instances of minor bleeding (< 20mls of bleeding) occurred and were easily controlled with topical diluted epinephrine solution. One pneumothorax occurred and was treated by chest tube placement without any adverse sequelae. There was no mortality associated with stent placement. No delayed hemorrhage or pneumothorax occurred. Patency results are shown in Table.
CONCLUSIONS: Airway bypass stent placement can be performed safely. In an animal model, the majority of the stents become occluded within 1 week but topical mitomycin application results in significant prolongation of patency.
9:00 a.m. BASIC SCIENCE LECTURE A Shortage of Oxygen: Lessons from the Summit of Mt. Everest John B.West, M.D. North Bldg., Hall C, Metro Toronto Convention Centre Introduced By: Joel D. Cooper
*By invitation 12002-03 Graham Fellow TUESDAY MORNING, APRIL 27, 2004
9:45 a.m. SCIENTIFIC SESSION (8 minute presentation, 12 minutes discussion) North Bldg., Hall C, Metro Toronto Convention Centre Moderators: Joel D. Cooper and Irving L. Kron
32. Single-stage Repair of Extensive Thoracic Aortic Aneurysms: Experience With The Arch-first Technique And Bilateral Anterior Thoracotomy Nicholas T. Kouchoukos, Michael C. Mauney*, Paolo Masetti*, Catherine F. Castner*; St. Louis, MO Discussant: R. Scott Mitchell
OBJECTIVE: Staged procedures for extensive aneurysmal disease of the thoracic aorta are associated with a substantial cumulative mortality (>20%) that includes hospital mortality for the two procedures and death (often from aortic rupture) in the interval between the two procedures. We have utilized a single-stage technique for operative repair of most or all of the thoracic aorta.
METHODS: Forty-three patients with extensive disease of the thoracic aorta were managed by a single-stage procedure using a bilateral anterior thoracotomy, circulatory arrest and reperfusion of the aortic arch vessels first to minimize brain ischemia. Twenty-six patients with chronic, expanding type A aortic dissections had previous operations for acute type A dissection (18), aortic valve replacement (5), or CABG (3). The remaining 17 patients had degenerative aneurysms (13) or chronic dissection (4). The ascending aorta and aortic arch were replaced in all patients combined with resection of various lengths of descending aorta (proximal 1/3 [9], proximal 2/3 [30], or all [4]). CABG and /or valve replacement were performed concomitantly in 17 patients.
RESULTS: Thirty day mortality was 7% (3 patients). Morbidity included reoperaton for bleeding (19%), assisted ventilation >48 hours (47%), tracheostomy (12%), and temporary renal dialysis (9%). No patient sustained a stroke. There have been 4 late deaths (2,18,34, and 79 months postoperatively). Two patients have undergone reoperation (false aneurysm, progression of disease).
CONCLUSIONS: The single stage, arch-first technique is a safe and suitable alternative to the two-stage procedure for repair of extensive thoracic aortic disease.
10:05 a.m. C. WALTON LILLEHEI RESIDENT FORUM AWARD PRESENTATION North Bldg., Hall C, Metro Toronto Convention Centre
10:10 a.m. INTERMISSION - VISIT EXHIBITS Exhibit Hall
10:55 a.m. SCIENTIFIC SESSION (8 minute presentation, 12 minutes discussion) North Bldg., Hall C, Metro Toronto Convention Centre Moderators: Joel D. CooperIrving L. Kron
33. Risk Factors Associated With Mortality and Reinterventions in 474 Neonates with Interruption of the Aortic Arch: A Congenital Heart Surgeons Society Study Brian W. McCrindle*, Christo I. Tchervenkov, Igor E. Konstantinov*, William G. Williams, Rodolfo A. Neirotti, Marshall L. Jacobs, Eugene H. Blackstone; Toronto, ON, Canada, Montreal, PQ, Canada, Grand Rapids, MI, Philadelphia, PA, Clevaland, OH Discussant: Ralph S. Mosca
OBJECTIVE: To determine outcomes and associated patient and management factors for neonates with interruption of the aortic arch (IAA).
METHODS: From 1987 to 1997, 474 neonates were enrolled prospectively from 33 institutions. Medical record data were submitted and abstracted. Competing risks methodology was used to determine demographic, morphologic, institutional and procedural risk factors for the time-related events of death and reintervention for left heart outflow and arch obstruction.
RESULTS: The majority had Type B IAA (71%), with 27% having associated anomalies other than VSD, including 51 patients with truncus arteriosus. Nineteen patients died without intervention and 3 had primary transplantation. The remaining 452 had IAA repair, with biventricular repair of all defects achieved in a single stage in 291 and multiple stages in 93, univentricular repair in 10, heart transplantation in 1, with 52 dying and 5 survivors without complete repair. Overall, there were 167 deaths after repair. During follow-up 55 patients had balloon dilation and 56 had reoperation for aortic arch obstruction. In addition, 138 patients had procedures for LV outflow obstruction either before, during (including 52 aortopulmonary connections) or after IAA repair (with reinterventions in 21), 72 of which were for subaortic obstruction. Procedures for both were performed in 23 patients. Competing risks at 15 years after IAA repair showed 42% alive with no arch reintervention. At least one arch reintervention had been performed in 29% (prolonged early hazard phase), with incremental risk factors including earlier date of birth, younger age at admission, presence of truncus arteriosus or aortopulmonary window or double outlet RV, failure to close the VSD at IAA repair, and 6 institutions (2 protective) and institutions entering less than 10 patients. None of the procedural characteristics of the arch repair were significant. Death without an arch reintervention was noted in 29% (steep early hazard phase), with incremental risk factors including earlier date of birth, male gender, lower birth weight, non-Type A IAA, presence of truncus arteriosus or multiple VSD's, smaller size VSD, need for dopamine at presentation, prostaglandins not used at presentation, lower weight at IAA repair, aortopulmonary connection (DKS) performed at IAA repair, arch augmentation not performed at IAA repair, and 5 institutions (1 protective).
CONCLUSIONS: Mortality is high for neonates with IAA, with an important risk of ongoing reinterventions in survivors after IAA repair, particularly those with associated truncus arteriosus. Risk of death and reinterventions improved over the study period.
*By Invitation 34. Pretransplant T-Cell Depletion and Tacrolimus Near-Monotherapy in Human Lung Transplantation Kenneth R. McCurry*, Adrianna Zeevi*, Diana B. Zaldonis*, Aldo lacono*, Thomas E. Starzl*; Pittsburgh, PA Discussant: 1Bruce K. Rosengard
OBJECTIVE: Lung transplantation remains plagued by poor outcomes from rejection as well as toxicities of immunosuppression. Current international results of one-year survival of 70-75% and 5-year survival of 45% remain significantly below those of other organs. We postulated that a strategy consisting of profound T-cell depletion prior to transplantation followed by minimization of post transplant immunosuppression (tacrolimus near-monotherapy) would result in improved outcomes and facilitate variable acquired tolerance.
METHODS: Between 6/02 and 10/03, 50 unselected patients (pts) underwent cadaveric lung transplantation. T-cell depletion was accomplished prior to allograft reperfusion with either high dose polyclonal anti-thymocyte globulin (Thymoglobulin (Thymo) 4-7 mg/kg iv, n=37) or the monoclonal agent Campath (30 mg, n=13). Post transplant immunosuppression consisted of tacrolimus (tac) in all pts and, in some pts, prednisone 5 mg/day (37/37 Thymo pts, 7/13 Campath pts). Weaning of tac was considered 4-6 months post transplant.
RESUITS: Pretreatment with either agent resulted in profound T-cell depletion. T-cell repopulation began and recovered, however, much faster following Thymo (CDS cells recovered by 3-4 months, CD4 cells returned to near normal by 6 months) than Campath. One-year actuarial survival for Thymo-treated pts was 82% (30-day survival 97%) (follow-up 288±99 days, range 115-465) while overall survival is 92% (12/13) for Campath-treated pts (follow-up 88±58 days, range 3-269). Twenty-seven percent (10/37) of thymo-treated pts required additional anti-T cell therapy for early rejection while there has been no rejection in Campath-treated pts. There have been 2 cases of CMV pneumonia's and 4 pts with opportunistic infections among Thymo-treated pts and 1 opportunistic infection in Campath-treated pts (all successfully treated). Of the 24 Thymo-treated pts more than 6 months from transplant, 17 are receiving tac only once a day (n=7) or a few times/wk (n=10) while both Campath-treated pts more than 6 months from transplant are weaning (1 pt on once a day tac and the other 4 times per wk).
CONCLUSIONS: These results demonstrate that our novel approach results in excellent outcomes following lung transplantation with variable ability to wean immunosuppression. There was less early rejection with Campath but whether lymphoid depletion with Thymo or Campath provides an advantage remains to be determined. This approach has the potential to significantly improve global outcomes following lung transplantation.
11:35 a.m. ADDRESS BY HONORED SPEAKER Leadership and Surgery: A View from Inside the Ocean Joseph Macinnis, M.D. North Bldg., Hall C, Metro Toronto Convention Centre Introduced By: Joel D. Cooper
12:20 p.m. ADJOURN FOR LUNCH - VISIT EXHIBITS North Bldg., Exhibit Hall Metro Toronto Convention Centre CARDIOTHORACIC RESIDENTS' LUNCHEON North Bldg., Suite 205, Metro Toronto Convention Centre
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