Patch Implantation Research Articles

Alternative method of patch implantation and creation for postinfarction ventricular septal defect repair by the infarct exclusion technique

Alternative method of patch implantation and creation for postinfarction ventricular septal defect repair by the infarct exclusion technique

Abstract 360: Implantation of an Induced Pluripotent Stem Cell Derived Cardiomyocyte Tissue Engineered Patch Improves Left Ventricular Function and Electro-mechanical Coupling in Rats With Heart Failure

Background: Chronic Heart Failure (CHF) is the leading cause of hospital readmissions and mortality in the US. Here we report the effects of surgically delivering a human bioengineered patch of human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) and fibroblasts on left ventricular (LV) function in rats with CHF. We evaluate improvements in LV systolic and diastolic function, electromechanical coupling and gene expression after patch implantation. Methods: Adult male Sprague-Dawley rats underwent left coronary artery ligation and were randomized to Sham (N=8), CHF (N=8-21), and CHF+hiPSC-CM patch (N=20-24). Heterogeneous hiPSC-CMs were seeded and co-cultured onto a vicryl matrix embedded with human dermal fibroblasts. Echocardiography was performed at 3 and 6 weeks post-randomization. Hemodynamic pressure measurements were performed at 6 weeks post-ligation with Millar solid state micromanometer pressure catheters. Open chest Electrophysiologic (EP) mapping was performed at 6 weeks post ligation. Gene expression was evaluated through qRT-PCR. Results: 48 hours into culture hiPSC-CMs patches displayed synchronized and spontaneous contractions which developed in robustness over time. At maximal robustness, contractions were visualized across the full thickness of the construct. Contractions were recorded at 36 + 5 beats BPM. Three weeks after patch implantation (6 weeks post ligation) the hiPSC-CM patch decreased (P<0.05) LV EDP (45%), Tau (29%), E/e’ (23%) and increased (P<0.05), e’/a’ (36%) with trending improvements in EF (14%) and e’ (20%). EP studies show electro-mechanical coupling between the patch and the native myocardium with normal activation through the patch and increases (P<0.05) voltage amplitude in CHF versus hiPSC-CM patch treated rats (1±0.5 mV vs 6±1.5mV). Rats treated with the hiPSC-CM patch showed significant (P<0.05) fold expression of Cx43 (3.3), ANG-1 (13.63), VEGF (3.8), βMYH7 (6.4) and IGF-1 (22.9) versus control. Conclusion: Cardiac patch implantation with hiPSC derived cardiomyocytes is an effective and feasible method of treating CHF with improvements in systolic function, diastolic function, and electro-mechanical coupling in rats with CHF.

Barrier Patch Implantation during Redo Surgery for Varicose Vein Recurrences in the Groin: 1-Year Results

Rerecurrences after redo surgery for recurrent varicose veins in the groin are a common problem. The present report looks at the efficacy of an additional barrier patch implantation in reducing these rerecurrences. A retrospective review of a prospectively collected database was conducted. This included 67 patients with 86 legs who underwent redo-groin surgery for symptomatic recurrences. In addition, a polytetrafluoroethylene-barrier patch was placed at the former saphenofemoral junction. All patients had undergone ligation and stripping of the great saphenous vein a mean of 13.9years earlier. All patients were examined by duplex ultrasound before and 1 year after the procedure. Perioperatively, minor complications occurred in 5.8% of cases, the groin infection rate was 2.4%. In 85 of 86 legs, the duplex follow-up examination was performed after 1 year. This revealed an overall rerecurrence rate of 12%, of which only 2.4% were caused by recurrent neovascularization in the groin bypassing the barrier patch. The remaining 9.6% were caused by different sites of reflux (pelvic veins and perforators). Redo-groin surgery with additional barrier patch implantation seems to be a safe and effective way to prevent rerecurrences in the groin. In our experience, it provided very promising 1-year results with a very low rate of recurrent neovascularization.

Application of the CardioCel bovine pericardial patch - a preliminary report.

IntroductionAnimal pericardial patches are widely used in adult and pediatric cardiac surgery. A search is ongoing for a new material with optimal surgical properties that will reduce intraoperative bleeding and the occurrence of restenosis, calcification, and pseudoaneurysms in long-term observation. One product of interest is the CardioCel bovine pericardial patch.AimEvaluation of the short-term results of CardioCel bovine pericardial patch implantation during pediatric cardiac surgery.Material and methodsThe study included 8 patients who underwent surgical correction of congenital cardiac defects between January 2015 and February 2016. Pericardial patches were used to repair supravalvular aortic stenosis and reconstruct the aortic arch and pulmonary arteries. The age of the patients ranged from 10 days to 14 years.ResultsThere were no hospital deaths. The new material exhibited satisfactory durability and elasticity during surgery, facilitating optimal adaptation of the patch to the patient's tissues. No significant bleeding was reported from the suture site. The median duration of follow-up was 58 days. During the follow-up, there were no symptoms of pseudoaneurysm formation, patch thickening, or calcification in the areas where the pericardial patches were implanted. No clinical or laboratory symptoms of infection were observed in locations where the new material was applied.ConclusionsSatisfactory surgical properties of the patch were observed intraoperatively. Positive results using the new pericardial patch were obtained in short-term follow-up.

Bioengineered epicardial patch regenerates the adult mammalian heart

Event Abstract Back to Event Bioengineered epicardial patch regenerates the adult mammalian heart Vahid Serpooshan1, Ke Wei2, 3, Mark Mercola2, 3 and Pilar Ruiz-Lozano1 1 Stanford University School of Medicine, Stanford Cardiovascular Institute and Department of Pediatrics, United States 2 University of California, San Diego, Department of Bioengineering, United States 3 Sanford-Burnham-Prebys Medical Discovery Institute, United States Adult mammals, unlike lower vertebrates, cannot effectively regenerate heart tissue, and myocyte loss following myocardial infarction (MI) is an important cause of human heart failure. Therefore, the elucidation of endogenous factors that control regeneration is of major scientific and therapeutic importance. Recent evidence suggests that the epicardium promotes myocardial regeneration; however, the mechanism remains largely unknown. In this study, we discovered that conditioned media from epicardial-like cultures enhance cardiomyogenesis in vitro[1]. We subsequently demonstrated that epicardial secreted factors embedded in a biomimetic type I collagen scaffold activate cardiomyocyte proliferation after ischemic heart injury (MI) in the mouse model (Figure1)[1]. An acellular type I collagen scaffold, endowed with specific physiomechanical properties approaching those of the embryonic epicardium, was generated utilizing plastic compression technique and used as cardiac patch (Figure 1a,b)[1]-[3]. Mass Spectrometry analysis identified Follistatin-like 1 (FSTL1) protein as a main component of the epicardial-derived cardiogenic activity. Fstl1 is expressed in the adult epicardium but declines strikingly following MI[1]. Application of FSTL1 to the epicardial surface of the heart by a compressed collagen patch recapitulated the activity of epicardial-conditioned media and restored cardiac function in the mouse model (Figure 2). The engineered patch-FSTL1 treatment diminished pathological remodeling (ventricular dilation and fibrosis), restored vascularization, and induced cell cycle entry of pre-existing αMHC+ cells after MI, consequently improving long-term cardiac function (Figure 2)[1]. The epicardial patch-FSTL1 function was also evaluated in the swine model of ischemia-reperfusion (I/R) injury[1]. As determined by delayed enhancement MRI, application of the patch to the epicardium over the injured tissue at week 1 post-I/R stimulated recovery of contractile function (%EF) in 2 weeks. The recovery remained stable for an additional two weeks and was in contrast to the steady decline seen without treatment or following treatment with patch alone (Figure 3b). FSTL1-treated pigs demonstrated the least scar size of all treatments (green lines in Figure 3c-d). Immunostaining 4 weeks after patch implantation demonstrated cardiomyocytes in the border zone and ischemic area with evident EdU labelling and midbody-localized aurora B kinase (indicative of cytokinesis) (Figure 3e-j)[1].

Progression of Aortic Regurgitation After Different Repair Techniques for Congenital Aortic Valve Stenosis.

We sought to characterize the incidence of AR progression and determine risk factors for AR progression in a consecutive series of infants and children after surgical correction of congenital aortic valvular and supravalvular stenosis. N = 30 patients underwent repair of the aortic valve for isolated congenital aortic valve stenosis (n = 14, 47 %) or combined with aortic regurgitation (AR, n = 16, 53%). N = 27 (90%) had a valvular and n = 3 patients (10%) presented with supravalvular pathology of their aortic valve. In n = 16 patients (53%) a bicuspid and in n = 2 (6%) patients, a unicuspid valve was present. Comparative survival was analyzed using the Cox model and log-rank calculations. Log-rank calculations were performed for variables reaching statistical significance in order to identify differences in survival between groups. Commissurotomy was performed in n = 20 patients, patch implantation in n = 4, cusp shaving in n = 8, cusp prolapse correction in n = 3, and cusp augmentation in n = 4 patients. In patients with combined dysfunction and preoperative AR, AR was successfully reduced by the initial procedure, and postoperatively the overall median AR grade was 1+ (range 0-2.5+, p = 0.001, for AR reduction among patients with any grade of preoperative AR). By the time of follow-up echocardiography, the median AR grade had significantly progressed toward 1.5+ (p = 0.004). At the time of mid-term follow-up at 3.2 years, none of the patients had moderate or severe AR grades >2.5+. Patients with a monocuspid aortic valve and patients who had some kind of patch implantation into their cusps or commissures or shaving of thickened cusps were more likely to present with progression of aortic regurgitation. Monocuspid aortic valve and patch implantation, as well as cusp shaving, are probably linked to AR progression. The standard procedure of commissurotomy results in an absolute rate of AR progression of 40 % over a medium-term follow-up period.

Abstract 425: Induced Pluripotent Stem Cell Derived Cardiomyocyte Tissue Engineered Scaffold Improves Left Ventricular Function and Electro-Mechanical Coupling in Rats with Heart Failure

Background: Chronic Heart Failure (CHF) is the leading cause of hospital readmissions in the United States. It may result from systolic or diastolic dysfunction, which often coexists. Here we report the effects of delivering human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) via a bioengineered patch on left ventricular function in rats with CHF. Methods: Adult male Sprague-Dawley rats underwent left coronary artery ligation and were randomized to Sham, CHF, and hiPSC-CM patch. High purity human hiPSC-CMs were obtained from Cellular Dynamics International, seeded and co-cultured onto a vicryl matrix embedded with human dermal fibroblasts. Echocardiography was performed at 3 and 6 weeks post-randomization. Hemodynamic pressure measurements were performed at 6 weeks post-ligation with Millar solid state micromanometer catheters. Open chest Electrophysiologic (EP) mapping was performed at 6 weeks post ligation. Results: Patches constructed with hiPSC-CMs displayed synchronized and spontaneous contractions within 48hrs of culture which developed in robustness over time. At maximal robustness, contractions were visualized across the full thickness of the construct. Contractions were recorded at 36+5 beats BPM. Three weeks after implantation, the hiPSC-CM patch decreased LV EDP (45%), Tau (29%), E/e’ (23%) and increased, EF (14%), e’ (20%), and e’/a’ (36%) versus CHF. EP studies show electro-mechanical coupling between the patch and the native myocardium with normal activation through the patch and increases (P<0.05) voltage amplitude in CHF versus hiPSC-CM patch treated rats (1±0.5 mV vs 6±1.5mV). Conclusion: Cardiac patch implantation with human iPSC derived cardiomyocytes is an effective and feasible method of treating CHF with improvements in systolic function, diastolic function, and electro-mechanical coupling in rats with CHF.

Repair effect of human acellular dermal matrix on filtering blebs leakage in rabbit eye

Background Package and tissue patch implantation are common methods for repair of filtering bleb leaking after anti-glaucoma surgery.But the scarring or re-leakage of filtering bleb probably occur again. Objective This study was to investigate the repair effect of acellular dermal matrix (ADM) on filtering bleb leaking in rabbit model and compare the effectiveness among ADM, amniotic membrane and conjunctival overlap. Methods Trabeculectomy was performed on 48 eyes of 24 New Zealand rabbits, and models of filtering bleb leaking were established.The models were randomized into ADM group, amniotic membrane group and conjunctival covering group based on randomized number table.ADM patches with 4 mm×4 mm were implanted across lamellar cornea and sclera at a bridge in the ADM group, and the same size of amniotic membranes were used in the amniotic membrane group, and conjunctiva was sutured to limbus in the conjunctiva overlap group.The intraocular pressure (IOP) was measured before surgery and 1 day, 1 week, 1 month, 3 months and 6 months after surgery.The biocompatibility of materials above was assessed under the slit lamp microscope, and the status of filtering bleb was evaluated and compared with anterior segment optical coherent tomography (AS-OCT) 1 day, 1 week, 1 month, 3 months and 6 months after surgery. Results Before surgery and 1 day, 1 week, 1 month, 3 months and 6 months after surgery, the IOP was (26.9±4.3), (16.6±5.1), (22.1±6.2), (18.3±6.5), (22.7±2.5), (23.4±1.4) mmHg in the AMD group, (29.9±5.4), (14.9±6.4), (21.6±7.8), (26.3±4.1), (26.0±4.2) and (23.0±5.3) mmHg in the amniotic membrane group, and (28.7±4.3), (15.7±7.0), (22.0±6.3), (28.2±4.1), (24.7±4.1), (23.0±2.7) mmHg in the conjunctival overlap group, showing significant differences among different groups and various time points (Fgroup=8.419, P=0.011; Ftime=15.543, P=0.000). The IOPs were significantly lower from 1 day through 3 months after operation than those before operation in the AMD group (P=0.000, 0.000, 0.006, 0.045); while the IOPs were reduced only from 1 day through 1 week after operation in comparison with before operation in the amniotic membrane group and the conjunctival overlap group (P=0.000, 0.001). One month after surgery, the IOPs were significantly declined in the ADM group compared with the amniotic membrane group and the conjunctival overlap group (P=0.001, 0.000). The grafts were clear under the slit lamp microscope and exhibited the valid filtering bleb until 3 months after operation under the AS-OCT in the ADM group.However, the valid filtering bleb remained only 1 month after surgery in the amniotic membrane group and the conjunctival overlap group.Neovascularization on the filtering bleb was found 3 months in the AMD group but 1 month in the amniotic membrane group and the conjunctival overlap group. Conclusions Compared with amniotic membrane and conjunctival tissue, ADM patch for the repair of filtering bleb leakage can increase the survival duration of filtering bleb and remain lower IOP. Key words: Human acellular dermal matrix; Trabeculectomy/complication; Filtering blebs; Leakage; Repair; Amniotic membrane; Intraocular pressure; Rabbit

Comparison of the efficacy of early transabdominal preperitoneal patch implantation and open tension-free repair in the treatment of adult inguinal hernia

Objective To compare the efficacy and complications of early transabdominal preperitoneal patch （TAPP） implantation and open tension-free repair in the treatment of adult inguinal hernia .Methods 84 adult patients with inguinal hernia were divided into two groups by random number table ,and 42 cases in each group .The control group was given Lichtenstein technique ,while the observation group underwent TAPP .The surgery situation, postoperative visual analogue scale （VAS） scores,postoperative morbidity and recurrence rate were compared between the two groups.Results The operative time,ambulation time,average length staying hospital and postoperative VAS scores of the observation group were （42.21 ±3.13） min,（1.13 ±0.21） d,（4.28 ±0.62） d and （2.28 ±0.22） points,which were significantly less than （65.72 ±3.62）min,（2.03 ±0.30）d,（7.87 ±0.83）d and （4.56 ±0.31） points of the control group（t=7.29,8.02,8.32,9.29,all P〈0.05）.The incidence rate of postoperative complica-tions and recurrence rate of the observation group were 11.90% and 2.38%,which were significantly lower than 26.19%and 16.66%of the control group（χ2 =12.52,14.39,all P〈0.05）.Conclusion The effect of TAPP in the treatment of adult inguinal hernia is remarkable ,and it is safe and minimally invasive ,which is easy to operate ,it has low recurrence rate ,rapid postoperative recovery and has better clinical value . Key words: Hernia; inguinal; Surgical procedures

Plasma-functionalized electrospun matrix for biograft development and cardiac function stabilization

Cardiac tissue engineering approaches can deliver large numbers of cells to the damaged myocardium and have thus increasingly been considered as a possible curative treatment to counteract the high prevalence of progressive heart failure after myocardial infarction (MI). Optimal scaffold architecture and mechanical and chemical properties, as well as immune- and bio-compatibility, need to be addressed. We demonstrated that radio-frequency plasma surface functionalized electrospun poly(ɛ-caprolactone) (PCL) fibres provide a suitable matrix for bone-marrow-derived mesenchymal stem cell (MSC) cardiac implantation. Using a rat model of chronic MI, we showed that MSC-seeded plasma-coated PCL grafts stabilized cardiac function and attenuated dilatation. Significant relative decreases of 13% of the ejection fraction (EF) and 15% of the fractional shortening (FS) were observed in sham treated animals; respective decreases of 20% and 25% were measured 4weeks after acellular patch implantation, whereas a steadied function was observed 4weeks after MSC-patch implantation (relative decreases of 6% for both EF and FS).

Half-dose enoxaparin vs. full-dose enoxaparin for postoperative bridging therapy in patients after cardiac surgery: Which dose regimen should be preferred?

Patients who require oral anticoagulation (OAC) after cardiac surgery due to an increased risk for thromboembolic events should receive bridging therapy with heparin until the INR is in a therapeutic range. For this purpose, unfractionated heparin (UFH) or low molecular weight heparin (LMWH) can be used. Recently published studies have demonstrated the safety and efficiency of therapeutic dose LMWH as bridging anticoagulant in cardiac surgery. The present study compares a full-therapeutic dose regimen with a half-therapeutic dose regimen of LMWH looking for safety and efficiency. This study represents a retrospective, single-center cohort study. In a period of 19 months all patients in whom a postoperative bridging therapy after cardiac surgery was necessary (atrial fibrillation, mechanical heart valve replacement, tricuspid valve repair, intracardiac patch implantation, excision of intracardiac tumors) were selected. In the first part of the study, patients received full-dose (FD = 1 mg/kg bodyweight twice daily) LMWH (Enoxaparin). Analogously, patients in the second part of the study were treated with half-dose (HD = 0.5 mg/kg bodyweight twice daily) LMWH. In case of renal insufficiency (GFR <30 ml/min) the dose was adjusted to one daily application. The duration of follow-up was the patients' entire stay in hospital. Main outcome parameters were bleeding, thromboembolic events, and death. The first dose of LMWH was given on the morning of the first postoperative day, considered that the bleeding risk was acceptable. OAC (Phenprocoumon) was started on the evening of the first postoperative day. Altogether 402 out of 3133 patients met the inclusion criteria (201 patients in each group). Despite a reduced renal function in the HD-group (p = 0.002) both groups were well matched. Mortality was significantly higher in the HD-group than in the FD-group (5.5% vs. 0.5%, p = 0.003) but not related to the anticoagulation regimen. We observed more bleeding events in the FD-group (11 vs. 5, p = 0.126) but vice versa more thromboembolic events in the HD-group (9 vs. 5, p = 0.277). In the HD-group postoperative dialysis was required more often (29 vs. 12, p = 0.011) and there was a higher incidence of patients who were psychic disorientated (42 vs. 26, p = 0.033). The hospital stay was longer in the FD-group (FD: 15.1 ± 9.3 days, HD 12.5 ± 8.1 days, p = 0.003). This study shows that a bridging therapy with LMWH is feasible and safe no matter which dose-regimen is used. The differences observed seem not to be related to the anticoagulation. The decision of using a full-dose or half-dose LMWH bridging regimen should be determined by the individual risk of the patient and the general bleeding risk of the procedure.

Biodegradable elastic patch plasty ameliorates left ventricular adverse remodeling after ischemia–reperfusion injury: A preclinical study of a porous polyurethane material in a porcine model

Myocardial infarction (MI) can lead to irreversible adverse left ventricular remodeling resulting in subsequent severe dysfunction. The objective of this study was to investigate the potential for biodegradable, elastomeric patch implantation to positively alter the remodeling process after MI in a porcine model. Yorkshire pigs underwent a 60-minute catheter balloon occlusion of the left circumflex artery. Two weeks after MI animals underwent epicardial placement of a biodegradable, porous polyurethane (poly(ester urethane)urea; PEUU) patch (MI+PEUU, n = 7) or sham surgery (MI+sham, n = 8). Echocardiography before surgery and at 4 and 8 weeks after surgery measured the end-diastolic area (EDA) and fractional area change (%FAC). All animals were humanely killed 8 weeks after surgery and hearts were histologically assessed. At 8 weeks, echocardiography revealed greater EDA values in the MI+sham group (23.6 ± 6.6 cm(2), mean ± standard deviaation) than in the MI+PEUU group (15.9 ± 2.5 cm(2)) (P < .05) and a lower %FAC in the MI+sham group (24.8 ± 7.6) than in the MI+PEUU group (35.9 ± 7.8) (P < .05). The infarcted ventricular wall was thicker in the MI+PEUU group (1.56 ± 0.5 cm) than in the MI+sham group (0.91 ± 0.24 cm) (P < .01). Biodegradable elastomeric PEUU patch implantation onto the porcine heart 2 weeks post-MI attenuated left ventricular adverse remodeling and functional deterioration and was accompanied by increased neovascularization. These findings, although limited to a 2-month follow-up, may suggest an attractive clinical option to moderate post-MI cardiac failure.

579 Aged Human Cells Rejuvenated by Cytokine-Enhancement of Biomaterials for Surgical Ventricular Restoration

579 Aged Human Cells Rejuvenated by Cytokine-Enhancement of Biomaterials for Surgical Ventricular Restoration

Placement of an Elastic Biodegradable Cardiac Patch on a Subacute Infarcted Heart Leads to Cellularization With Early Developmental Cardiomyocyte Characteristics

BackgroundPlacement of an elastic biodegradable patch onto a subacute myocardial infarct (MI) provides temporary elastic support that may act to effectively alter adverse left ventricular (LV) remodeling processes. MethodsTwo weeks after permanent left coronary ligation in Lewis rats, the infarcted anterior wall was covered with polyester urethane urea (MI + PEUU; n = 15) or expanded polytetrafluoroethylene (MI + ePTFE; n = 15) patches, or had no implantation (MI + sham; n = 12). Eight weeks after surgery, cardiac function and histology were assessed. ResultsThe ventricular wall in the MI + ePTFE and MI + sham groups was composed of fibrous tissue, whereas PEUU implantation induced α-smooth muscle actin–positive muscle bundles coexpressing sarcomeric α-actinin and cardiac-specific troponin-T. This pattern of colocalization was also found in developing embryonic myocardium. Cardiac transcription factors Nkx-2.5 and GATA-4 were strongly expressed in the muscle bundles. In the MI + sham group, end-diastolic LV cavity area (EDA) increased and the percentage of fractional area change (%FAC) decreased. For ePTFE patched animals, both EDA and %FAC decreased. In contrast, with MI + PEUU patching, %FAC increased and EDA was maintained. With dobutamine-stress echocardiography, MI + PEUU patched LVs possessed contractile reserve significantly larger than the MI + sham group. ConclusionsMI + PEUU patch implantation onto subacute infarcted myocardium induced muscle cellularization with characteristics of early developmental cardiomyocytes as well as providing a functional reserve.

Pericardial Patch Angioplasty Heals via an Ephrin-B2 and CD34 Positive Cell Mediated Mechanism

ObjectivePericardial patches are commonly used in vascular surgery to close arteriotomies. The mechanism of early healing after patch implantation is still not well defined. We used a rat aortic patch model to assess pericardial patch healing and examined Ephrin-B2, a marker of arterial identity, expression within the post-implantation patch. We also determined whether endothelial progenitor cells (EPC) are associated with early patch healing in the arterial environment.MethodsWistar rats (200–250 grams) underwent infrarenal aortic arteriotomy and then closure via bovine or porcine pericardial patch angioplasty. Control groups included subcutaneously implanted patches. Patches were harvested at 0–30 days and analyzed by histology, immunohistochemistry, immunofluorescence and Western blot as well as quantitative PCR.ResultsPrior to implantation, pericardial patches are largely composed of collagen and are acellular. Following arterial implantation, increasing numbers of CD68-positive cells as well as Ephrin-B2 and CD34 dual-positive cells are found within both bovine and porcine pericardial patches, whereas the infiltrating cells are negative for vWF and α-actin. Porcine patches have a luminal monolayer of cells at day 7, compared to bovine patches that have fewer luminal cells. Subcutaneously implanted patches do not attract Ephrin-B2/CD34-positive cells. By day 30, both bovine and porcine pericardial patches develop a neointima that contains Ephrin-B2, CD34, and VEGFR2-positive cells.ConclusionBoth CD68-positive and Ephrin-B2 and CD34 dual-positive cells infiltrate the pericardial patch early after implantation. Arteriotomy closure via pericardial patch angioplasty shows patch adaptation to the arterial environment that may involve a foreign body response as well as localization of EPC. Arterial remodeling of pericardial patches support endothelialization and may represent a paradigm of healing of scaffolds used for tissue engineering.

Surgical treatment of right ventricular outflow tract obstruction after Tetralogy of Fallot repair

Situs solitus of viscera and atria, D-looped ventricle with atrioventricular concordance, and inverted normally related great arteries with ventriculoarterial concordance characterize the segmental anatomy of an extremely rare {S,D,I} variant of Tetralogy of Fallot. The main pulmonary artery is rightward of the aorta and the right coronary artery crosses over the right ventricular outflow tract from left to right to reach the right atrioventricular groove. Our patient had undergone a neonatal repair due to persistent cyanosis with the implantation of a pericardial infundibular patch after the diagnosis of Tetralogy of Fallot {S,D,I}. He presented with an annular right ventricular outflow tract obstruction at 19 months of age. We describe the surgical approach employing a transannular patch implantation for the relief of the annular right ventricular outflow tract obstruction.

Metabolic pathway and distribution of superparamagnetic iron oxide nanoparticles: in vivo study

Background:Experimental tissue fusion benefits from the selective heating of superparamagnetic iron oxide nanoparticles (SPIONs) under high frequency irradiation. However, the metabolic pathways of SPIONs for tissue fusion remain unknown. Hence, the goal of this in vivo study was to analyze the distribution of SPIONs in different organs by means of magnetic resonance imaging (MRI) and histological analysis after a SPION-containing patch implantation.Methods:SPION-containing patches were implanted in rats. Three animal groups were studied histologically over six months. Degradation assessment of the SPION-albumin patch was performed in vivo using MRI for iron content localization and biodistribution.Results:No SPION degradation or accumulation into the reticuloendothelial system was detected by MRI, MRI relaxometry, or histology, outside the area of the implantation patch. Concentrations from 0.01 μg/mL to 25 μg/mL were found to be hyperintense in T1-like gradient echo sequences. The best differentiation of concentrations was found in T2 relaxometry, susceptibility-sensitive gradient echo sequences, and in high repetition time T2 images. Qualitative and semiquantitative visualization of small concentrations and accumulation of SPIONs by MRI are feasible. In histological liver samples, Kupffer cells were significantly correlated with postimplantation time, but no differences were observed between sham-treated and induction/no induction groups. Transmission electron microscopy showed local uptake of SPIONs in macrophages and cells of the reticuloendothelial system. Apoptosis staining using caspase showed no increased toxicity compared with sham-treated tissue. Implanted SPION patches were relatively inert with slow, progressive local degradation over the six-month period. No distant structural alterations in the studied tissue could be observed.Conclusion:Systemic bioavailability may play a role in specific SPION implant toxicity and therefore the local degradation process is a further aspect to be assessed in future studies.

Modification of a Hybrid Technique for Closure of Muscular Ventricular Septal Defects in a Pig Model

Closure of muscular ventricular septal defects (mVSDs) beyond the moderator band is still a challenge for both surgeons and interventional cardiologists. We evaluated a new technique in a pig model for hybrid patch closure of mVSDs via 2 stab wound incisions in the left ventricle (LV) without cardiopulmonary bypass. Ten pigs underwent left anterolateral thoracotomy to expose the LV. mVSDs were created via a stab wound incision of the lateral wall of the LV under epicardial echocardiographic control. The patch system was forwarded through a second puncture of the LV apex and positioned in front of the mVSD. The stapler for fixation of the patch was introduced through the same incision as used for VSD creation. Finally, the patch was attached to the septum with nitinol anchors under epicardial echocardiographic and fluoroscopic guidance. Finally, detailed echocardiographic evaluation was done. All hearts were explanted, and macroscopic evaluation was done, either immediately after patch implantation (n = 4) or after 90 days (n = 6). mVSD creation was successful in all pigs. Closure of mVSDs was successful in 8 of 10 pigs, as confirmed by echocardiography, hemodynamic measurements, and macroscopic examination. One patch embolized through the mVSD into the pulmonary artery because of insecure fixation, and 1 animal died during the procedure because of ventricular fibrillation. The final echocardiographic evaluation revealed good LV function and no damage to the valves. Closure of mVSDs can be successfully performed in a hybrid technique on the beating heart with 2 stab wound incisions; however, further modifications need to be developed before clinical application.

Attenuation of Left Ventricular Adverse Remodeling With Epicardial Patching After Myocardial Infarction

Background Previous studies suggested that epicardial patch applied to the infarcted site after acute myocardial infarction (MI) can alleviate left ventricular (LV) remodeling and improve cardiac performance; however, the effects of regional epicardial patch on chronic phase of LV remodeling remain unclear. Methods and Results We studied 20 pigs with MI induced by distal embolization and impaired LV ejection fraction (LVEF <45%) as detected by gadolinium-enhanced cardiac magnetic resonance imaging (MRI). Eight weeks post-MI, all animal underwent open chest procedure for sham surgery (control, n = 12) or patch implantation over the infarcted lateral LV wall (patch group, n = 12). In the patch group, +dP/dt increased and LV end-diastolic pressure decreased at 20 weeks compared with immediately post-MI and at 8 weeks ( P < .05), but not in the control group ( P > .05). As determined by cardiac MRI, LV end-diastolic and end-systolic volumes increased at 20 weeks compared with 8 weeks in both groups ( P < .05). However, the increase in LV end-diastolic volume (+14.1 ± 1.8% vs. +6.6 ± 2.1%, P = .015) and LV end-systolic volume (+12.1 ± 2.4% vs. −4.7 ± 3.7%, P = .0015) were significantly greater in the control group compared with the patch group. Furthermore, the percentage increase in LVEF (+17.3 ± 4.9% vs. +4.1 ± 3.9%, P = .048) from 8 to 20 weeks was significantly greater in the patch group compared with the control group. Histological examination showed that LV wall thickness at the infarct region and adjacent peri-infarct regions were significantly greater in the patch group compared with the control group ( P < .05). Conclusion Regional application of a simple, passive synthetic epicardial patch increased LV wall thickness at the infarct region, attenuated LV dilation, and improved LVEF and +dP/dt in a large animal model of MI.

Glutaraldehyde treatment of allograft tissue decreases allosensitization after the Norwood procedure

Cryopreserved allograft tissue used in the Norwood procedure for infants with hypoplastic left heart syndrome causes a marked immunologic sensitization that may complicate future heart transplantation. Treatment of the allograft tissue before implantation may prevent this sensitization. The purpose of this study was to assess the anti-human leukocyte antigen antibody response to glutaraldehyde-treated allograft tissue used in the repair of hypoplastic left heart syndrome. Since June 2005, the University of Alberta has subjected allograft vascular tissue used in the Norwood procedure to glutaraldehyde treatment. An observational study was designed to assess whether glutaraldehyde treatment of the allograft tissue affected subsequent panel reactive antibody after patch implantation. Panel reactive antibodies for class I (human leukocyte antigen-A, B, C) and class II (human leukocyte antigen-DR, DQ) antibodies were measured 4 months postoperatively using flow cytometry. Fourteen patients underwent a Norwood procedure using glutaraldehyde-treated allograft tissue. Historical controls consisted of 12 patients who underwent a Norwood procedure using untreated allograft tissue. At 4 months, infants who had received glutaraldehyde-treated allograft tissue had lower class I panel reactive antibody (7.3% +/- 17.4% [median, 0%] vs 61.9% [median, 73%] +/- 39.9%; P = .0005) and class II panel reactive antibody (6.1% [median, 0%] +/- 22.7% vs 49.3% [median, 63%] +/- 41.9%, P = .001) compared with the historical controls. Intraoperative glutaraldehyde treatment of allograft tissue used in hypoplastic left heart syndrome repair prevents the profound immunologic sensitization that occurs in the majority of infants undergoing surgical palliation. In patients requiring subsequent heart transplantation, this decreases the risk of antibody-mediated rejection and increases the likelihood of finding a suitable donor, thus improving access to transplantation.