A Novel Bioresorbable Film Reduces Postoperative Adhesions After Infant Cardiac Surgery

Experimental Study of Products Based on Biocompatible Polymer Material from Methacrylic Oligomers as a Potential Barrier for Preventing Adhesions in Cardiac Surgery

The effectiveness and safety of two types of samples based on a biocompatible polymer material made of methacrylic oligomers (Reperen) as a potential antiadhesion pericardial barrier were evaluated in in vitro and in vivo experiments. Two kinds of samples, reinforced with a polyamide mesh and without reinforcement, were used. In in vitro experiments, no adhesion and aggregation of human fibroblasts to the test samples were detected. In in vivo experiments, the samples implanted to rats into the thigh muscles were easily separated from the surrounding tissues 1, 2, and 3 weeks after implantation, being weakly fixed only in the area of the edges. Histological examination at week 2 after implantation revealed no differences between the experimental and control groups. At week 1 and 3, fibrosis and inflammation were more pronounced in animals of the control group (with simulated implantation). The properties demonstrated by both samples of Reperen barriers (with and without polyamide mesh reinforcement) in vivo and in vitro allow considering them as a potential antiadhesion pericardial barrier for clinical use.

PMMA-induced biofilm promotes Schwann cells migration and proliferation mediated by EGF/Tnc/FN1 to improve sciatic nerve defect

Objective

The purpose of this study is to investigate the role of PMMA-induced biofilm in nerve regeneration compared with silicone-induced biofilm involved in the mechanism.

Methods

PMMA or silicon rods were placed next to the sciatic nerve to induce a biological membrane which was assayed by PCR, Western blot, immunohistochemistry, immunofluorescence and proteomics. A 10 mm sciatic nerve gaps were repaired with the autologous nerve wrapped in an induced biological membrane. The repair effects were observed through general observation, functional evaluation of nerve regeneration, ultrasound examination, neural electrophysiology, the wet weight ratio of bilateral pretibial muscle and histological evaluation. Cell proliferation and migration of Schwann cells co-cultured with EGF-treated fibroblasts combined with siRNA were investigated.

Results

The results indicated that expression of GDNF, NGF and VEGF along with neovascularization was similar in the silicone and PMMA group and as the highest at 6 weeks after operation. Nerve injury repair mediated by toluidine blue and S100β/NF200 expression, the sensory and motor function evaluation, ultrasound, target organ muscle wet-weight ratio, percentage of collagen fiber, electromyography and histochemical staining were not different between the two groups and better than blank group. EGF-treated fibroblasts promoted proliferation and migration may be Tnc expression dependently.

Conclusion

Our study suggested that PMMA similar to silicon induced biofilm may promote autogenous nerve transplantation to repair nerve defects through EGF/Tnc/FN1 to increase Schwann cells proliferation and migration.

Postsurgical Adhesions: Is There Any Prophylactic Strategy Really Working?

Postoperative adhesions are a frequent complication encountered after surgical procedures, mainly after intraperitoneal interventions. To this day, the pathophysiological mechanism behind the process of adhesions formation is not completely known. There are many strategies proposed as prophylaxis methods, involving surgical techniques, drugs or materials that prevent adhesions and even state of the art technologies such as nanoparticles or gene therapy. The aim of our review is to present these innovative approaches and techniques for postoperative adhesions prevention. After a thorough scientific database query, we selected 84 articles published in the past 15 years that were relevant to our topic. Despite all the recent groundbreaking discoveries, we are at an early stage of understanding the complexity of the adhesion formation mechanism. Further investigations should be made in order to create an ideal product for safe clinical use for prevention.

Outcomes of expanded polytetrafluoroethylene pericardial membrane implantation in left ventricular assist device explantation and heart transplantation

OBJECTIVES

Redo sternotomy and explantation of left ventricular assist devices (LVAD) for heart transplantation (HT) involve prolonged dissection, potential injury to mediastinal structures and/or bleeding. Our study compared a complete expanded polytetrafluoroethylene (ePTFE) wrap versus minimal or no ePTFE during LVAD implantation, on outcomes of subsequent HT.

METHODS

Between July 2005 and July 2018, 84 patients underwent a LVAD implant and later underwent HT. Thirty patients received a complete ePTFE wrap during LVAD implantation (Group 1), and 54 patients received either a sheet of ePTFE placed in the anterior mediastinum or no ePTFE (Group 2).

RESULTS

Baseline characteristics were similar between Groups 1 and 2. Surgeons reported subjective improvements in speed, predictability, and safety of dissection with complete ePTFE compared with minimal or no ePTFE. Time from incision to initiation of cardiopulmonary bypass (CPB) were similar between groups (97 ± 38 vs. 89 ± 29 min, p = .3). Injury to mediastinal structures during the dissection was similar between groups (10% vs. 11%, p > .9). While surgeons reported less intraoperative bleeding in Group 1 (43% vs. 61%), this trend did not reach significance (p = .1). In-hospital mortality, intensive care unit length of stay and hospital length of stay were similar between both groups.

CONCLUSIONS

In patients undergoing LVAD explant-HT, there was a trend toward reduced surgeon reported intraoperative bleeding with ePTFE placement. Despite qualitatively reported greater ease and speed of mediastinal dissection with ePTFE membrane placement, time to initiation of CPB did not differ, likely because surgeons remained cautious, allowing extra time for unanticipated difficulties.

Significant adhesion reduction and time saving in pediatric heart surgery with 4DryField PH: A retrospective, controlled study

Adhesions formation after surgery for congenital heart defects can complicate follow-up procedures due to bleeding from detached adhesion bands, injury to cardiac structures or large vessels, all of which do prolong operation times. The problem is enhanced by the fact that detached adhesions are predilection sites for new adhesions setting off a downward spiral. 4DryField® PH gel barrier has demonstrated high efficacy in reducing postoperative adhesions in general surgical and gynecological studies. This retrospective controlled study of 22 patients evaluates whether these positive results can be confirmed in pediatric cardiac surgery. Adhesions were scored from photographs of follow-up interventions by an independent cardiac surgeon blinded to group assignment. The publication provides not only score numbers but also original photographs of all sites for better traceability and transparency. In addition, timesaving due to reduced adhesions was evaluated. Results show a significantly reduced adhesion score for the 4DryField® group. Importantly, this resulted in a significantly shorter period between skin incision and start of cardiopulmonary bypass. In addition, timesaving due reduced adhesion formation was evaluated. The use of 4DryField® was safe, although higher doses per kg were used than in adults.

Barrier materials for prevention of surgical adhesions: systematic review

BACKGROUND

Postoperative surgical adhesions constitute a major health burden internationally. A wide range of materials have been evaluated, but despite constructive efforts and the obvious necessity, there remains no specific barrier widely utilized to prevent postoperative adhesion formation. The aim of this study was to highlight and characterize materials used for prevention of postoperative surgical adhesions in both animal and human studies.

METHODS

A systematic review was performed of all original research articles presenting data related to the prevention of postoperative adhesions using a barrier agent. All available observational studies and randomized trials using animal models or human participants were included, with no restrictions related to type of surgery. PubMed and Embase databases were searched using key terms from inception to August 2019. Standardized data collection forms were used to extract details for each study and assess desirable characteristics of each barrier and success in animal and/or human studies.

RESULTS

A total of 185 articles were identified for inclusion in the review, with a total of 67 unique adhesion barrier agents (37 natural and 30 synthetic materials). Desirable barrier characteristics of an ideal barrier were identified on review of the literature. Ten barriers achieved the primary outcome of reducing the incidence of postoperative adhesions in animal studies followed with positive outputs in human participants. A further 48 materials had successful results from animal studies, but with no human study performed to date.

DISCUSSION

Multiple barriers showed promise in animal studies, with several progressing to success, and fulfilment of desirable qualities, in human trials. No barrier is currently utilized commonly worldwide, but potential barriers have been identified to reduce the burden of postoperative adhesions and associated sequelae.

A Modfied Nuss Procedure for Recurrent Pectus Excavatum of Adults

Background

Limited data exist for adults with recurrent pectus excavatum (PE) treated with minimally invasive surgical repair.

Methods

Between July 2008 and December 2020, forty-two adult patients with recurrent PE underwent a modified Nuss procedure with a newly designed bar in our center. A small vertical subxiphoid incision was used to separate severe adhesions when necessary. Multiple steel wires were sutured, and the rib space was narrowed to firmly fix the bar. The primary end point was Haller index change after operation. The secondary end points included length of stay after operation, short-term and long-term complications.

Results

The mean patient age was 22.02 ± 3.49 years. The mean Haller index was 4.59 ± 1.09. A subxiphoid incision was performed in 12 patients. Thirty-nine patients had one bar placed, and 3 patients required two bars. Sixteen patients had 3 or more wires fixation, and 4 patients needed to have their intercostal space narrowed. There was no perioperative death, and the mean hospitalization was 5.57 ± 2.47 days. The Haller index reduced to 3.03 ± 0.41 after the operation (t = 11.85, p < 0.001). During the follow-up, there were 3 patients who developed non-infective wound effusion; bar rotations occurred in 3 patients. Twenty patients had the bar removed, post-bar removal Haller index was significantly reduced compared to the preoperative Haller index (2.89 ± 0.37 vs. 4.72 ± 1.05, t = 8.96, p < 0.001).

Conclusions

The modified Nuss procedure with a new titanium alloy bar can achieve good results for adult patients with recurrent PE.

4-Arm PEG-Functionalized Decellularized Pericardium for Effective Prevention of Postoperative Adhesion in Cardiac Surgery

Postoperative adhesions are a very common and serious complication in cardiac surgery, and the development of an effective anti-adhesion membrane showing resistance to the physical stimulus generated by the pulsation of the heart is desirable. In this study, an anti-adhesion material was developed through amine coupling between decellularized bovine pericardia (dBPCs) and 4-arm poly(ethylene glycol) succinimidyl glutarate (4-arm PEG-NHS) for the postoperative care of cardiac surgical patients. The efficacy of the 4-arm PEG-functionalized dBPCs in the prevention of adhesions after cardiac surgery was investigated in a rabbit heart adhesion model. The dBPCs meet the requirements for biocompatibility, flexibility, and sufficient suturable strength, and the 4-arm PEG moieties provide an anti-adhesion effect by the high excluded volume interactions of the PEG chains with proteins. The 4-arm PEG-functionalized dBPCs had a significantly greater anti-adhesion effect than the other materials tested and showed re-establishment of the mesothelial monolayer. These results suggested that the 4-arm PEG-functionalized dBPCs are a favorable material for an anti-adhesion membrane.

Adhesion barriers in cardiac surgery: A systematic review of efficacy

BACKGROUND

Postoperative pericardial adhesions have been associated with increased morbidity, mortality, and surgical difficulty. Barriers exist to limit adhesion formation, yet little is known about their use in cardiac surgery. The study presented here provides the first major systematic review of adhesion barriers in cardiac surgery.

METHODS

Scopus and PubMed were assessed on November 20, 2020. Inclusion criteria were clinical studies on human subjects, and exclusion criteria were studies not published in English and case reports. Risk of bias was evaluated with the Cochrane Risk of Bias Tool. Barrier efficacy data was assessed with Excel and GraphPad Prism 5.

RESULTS

Twenty-five studies were identified with a total of 13 barriers and 2928 patients. Polytetrafluoroethylene (PTFE) was the most frequently evaluated barrier (13 studies, 67% of patients) with adhesion formation rate of 37.31% and standardized tenacity score of 26.50. Several barriers had improved efficacy. In particular, Cova CARD had a standardized tenacity score of 15.00.

CONCLUSIONS

Overall, the data varied considerably in terms of study design and reporting bias. The amount of data was also limited for the non-PTFE studies. PTFE has historically been effective in preventing adhesions. More recent barriers may be superior, yet the current data is nonconfirmatory. No ideal adhesion barrier currently exists, and future barriers must focus on the requirements unique to operating in and around the heart.

Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

Preventing post-surgical cardiac adhesions with a catechol-functionalized oxime hydrogel

Post-surgical cardiac adhesions represent a significant problem during routine cardiothoracic procedures. This fibrous tissue can impair heart function and inhibit surgical access in reoperation procedures. Here, we propose a hydrogel barrier composed of oxime crosslinked poly(ethylene glycol) (PEG) with the inclusion of a catechol (Cat) group to improve retention on the heart for pericardial adhesion prevention. This three component system is comprised of aldehyde (Ald), aminooxy (AO), and Cat functionalized PEG mixed to form the final gel (Ald-AO-Cat). Ald-AO-Cat has favorable mechanical properties, degradation kinetics, and minimal swelling, as well as superior tissue retention compared to an initial Ald-AO gel formulation. We show that the material is cytocompatible, resists cell adhesion, and led to a reduction in the severity of adhesions in an in vivo rat model. We further show feasibility in a pilot porcine study. The Ald-AO-Cat hydrogel barrier may therefore serve as a promising solution for preventing post-surgical cardiac adhesions.

Novel Trilaminar Polymeric Antiadhesion Membrane Prevents Postoperative Pericardial Adhesion

BACKGROUND

Postoperative pericardial adhesion formation is a prominent cause of morbidity and death in cardiovascular surgery, but there is still no ideal prevention method, especially in redo cases. This study investigated a novel antiadhesion trilaminar polymeric film compared with the Gore PRECLUDE Pericardial Membrane (W. L. Gore & Associates, Flagstaff, AZ) and a negative control.

METHODS

Our novel trilaminar membrane is composed of polyvinyl alcohol (PVA) and carboxymethylcellulose (CMC). An established pericardial adhesion rabbit model was used to test the property of the membrane. After sternotomy, a portion of pericardium was resected and the epicardium was abraded. Rabbits (n = 24) were randomly assigned to 3 groups: control group, no trilaminar membrane or expanded polytetrafluoroethylene (ePTFE); ePTFE group, or trilaminar membrane group (PVA-CMC group). Evaluation of adhesion formation was performed by resternotomy 4 weeks after the operation.

RESULTS

The degree of tissue adhesion surrounding the heart in the PVA-CMC group was significantly less than in the control (P < .01) and ePTFE (P < .05) groups. The inflammation score in group PVA-CMC was significantly lower than that in the ePTFE (P < .01) and control (P < .01) groups. The fibrosis score was significantly lower in group PVA-CMC than that in the ePTFE (P < .05) and control (P < .01) groups.

CONCLUSIONS

The novel trilaminar membrane effectively reduced postoperative pericardial adhesions. The placement of the trilaminar membrane at the time of sternal closure provides a novel combination to minimize the extent and severity of pericardial adhesions while providing a physical barrier between the sternum and the cardiac structures.

Management of retrosternal adhesion after median sternotomy by controlling degradation speed of a dextran and ε-poly (L-lysine)-based biocompatible glue

OBJECTIVE

Retrosternal adhesion after median sternotomy possibly raises the risk of cardiac injury at resternotomy. A biodegradable glue "Lydex" is composed of food additives, dextran and ε-poly (L-lysine), and the degradation speed can be controlled by the composition. In the present study, we evaluated the preventative effect of Lydex on retrosternal adhesion and the relationship between degradation speed and the progression of retrosternal fibrosis.

METHODS

Japanese white rabbits are subjected to median sternotomy. Lydex 1, 2 and 3 were loaded at the retrosternal space of rabbits in allocated groups before sternal closure, respectively (n = 11 for each group). Retrosternal adhesion was macroscopically evaluated after surgery. Retainment of Lydex, retrosternal fibrosis and the infiltration of macrophages are histologically evaluated, respectively.

RESULTS

All Lydex groups exhibited less retrosternal adhesion at 4 weeks after loading compared to unloaded control. The degradation speed of Lydex varied according to the compositions. Lydex with faster degradation (Lydex 2 or Lydex 3) showed lower progression of retrosternal fibrosis compared to that with slower degradation (Lydex 1) [fibrosis ratio: control vs Lydex 1 vs Lydex 2 vs Lydex 3: 0.60 ± 0.15 vs 0.18 ± 0.17 vs 0.00 ± 0.00 vs 0.00 ± 0.00, P = 0.0005 (Lydex 1 vs Lydex 2), P = 0.0005 (Lydex 1 vs Lydex 3)]. Retrosternal infiltrations of macrophages in Lydex 1 and Lydex 3 groups are not higher compared to that in unloaded control.

CONCLUSIONS

The degradation speed of Lydex could be controlled according to the compositions. The degradation speed affected the progression of retrosternal fibrosis.

Bioresorbable electrospun gelatin/polycaprolactone nanofibrous membrane as a barrier to prevent cardiac postoperative adhesion

Post-cardiac surgical sternal and epicardial adhesions increase the risk and complexity of cardiac re-operative surgeries, which represent a significant challenge for patients with the congenital cardiac disease. Bioresorbable membranes can serve as barriers to prevent postoperative adhesions. Herein, we fabricated a bioresorbable gelatin/polycaprolactone (GT/PCL) composite membrane via electrospinning. The membrane was characterized in terms of morphology, mechanical properties, and biocompatibility. We then evaluated its efficacy as a physical barrier to prevent cardiac operative adhesions in a rabbit model. Our results showed that the membrane had a nanofibrous structure and was sturdy enough to be handled for the surgical procedures. In vitro studies with rabbit cardiac fibroblasts demonstrated that the membrane was biocompatible and inhibited cell infiltration. Further application of the membrane in a rabbit cardiac adhesion model revealed that the membrane was resorbed gradually and effectively resisted the sternal and epicardial adhesions. Interestingly, six months after the operation, the GT/PCL membrane was completely resorbed with simultaneous ingrowth of host cells to form a natural barrier. Collectively, these results indicated that the GT/PCL membrane might be a suitable barrier to prevent sternal and epicardial adhesions and might be utilized as a novel pericardial substitute for cardiac surgery. STATEMENT OF SIGNIFICANCE: Electrospinning is a versatile method to prepare nanofibrous membranes for tissue engineering and regenerative medicine applications. However, with the micro-/nano-scale structure and high porosity, the electrospun membrane might be an excellent candidate as a barrier to prevent postoperative adhesion. Here we prepared an electropun GT/PCL nanofibrous membrane and applied it as a barrier to prevent sternal and epicardial adhesions. Our results showed that the membrane had sufficient mechanical strength, good biocompatibility, and effectively resisted the sternal and epicardial adhesions. What's more, the membrane was bioresorbable and allowed simultaneous ingrowth of host cells to form a natural barrier. We believe that the current will inspire more research on nanomaterials to prevent postoperative adhesion applications.

A fibrin-coated pericardial extracellular matrix prevented heart adhesion in a rat model

As most surgical treatments pose a risk of tissue adhesion, methods to prevent adhesion are needed across various surgical fields. In this study, we investigated the use of a decellularized pericardium with fibrin glue to prevent rat heart adhesion. Porcine pericardia were decellularized by a high-hydrostatic pressure method. Cells adhered to the resulting pericardial extracellular matrix (ECM) during an in vitro cell-seeding test, but fibrin-coated pericardial ECM showed reduced cell adhesion. In a rat surgical model of heart adhesion, the fibrin-coated pericardial ECM did not adhere to the heart and mesothelial cell adhesion was observed on the ECM surface. Notably, the anti-adhesion effect of fibrin-coated pericardial ECM was observed 4 weeks after surgery. These results support the utility of fibrin-coated pericardial ECM as an adhesion prevention material for cardiovascular surgery. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1088-1094, 2019.

Postoperative Pericardial Adhesion Prevention Using Collagen Membrane in Pigs: A Pilot Study

Objective:

The operating procedure of a resternotomy in open-heart surgery is a complicated procedure with potentially problematic outcomes partly due to potential adhesions in the pericardial cavity and retrosternal space. Use of a collagen membrane has shown encouraging results in adhesion prevention in several regions of the body. This study was designed to evaluate the effectiveness of the use of this collagen membrane in the prevention of pericardial adhesions.

Materials and methods:

A total of 12 pigs were divided randomly into 2 groups: an experimental group in which collagen membranes were used and a control group. After sternotomy and an anterior pericardiectomy, the epicardial surface was exposed to room air and irrigated with saline, and an epicardial abrasion was performed using a sponge. The pericardial defect was repaired using a collagen membrane in the experimental group or left uncovered in the control group. After 8 to 12 weeks, the pigs were killed, and a resternotomy was performed by a single-blinded surgeon enabling the evaluation of adhesions. The heart was then removed and sent for microscopic assessment conducted by a single-blinded pathologist.

Results:

The resternotomy operations performed using a collagen membrane demonstrated a nonstatistically significant trend of fewer macroscopic and microscopic adhesions in all regions (P > .05), particularly in the retrosternal and defect regions.

Conclusions:

This study showed nonstatistically significant differences between the outcomes in the collagen membrane group and the control group in both macroscopic and microscopic adhesion prevention. Due to the many limitations in animal study design, further studies in human models will be needed before the true value of this procedure can be evaluated.

Combinatorial release of dexamethasone and amiodarone from a nano-structured parylene-C film to reduce perioperative inflammation and atrial fibrillation

Suppressing perioperative inflammation and post-operative atrial fibrillation requires effective drug delivery platforms (DDP). Localized anti-inflammatory and anti-arrhythmic agent release may be more effective than intravenous treatment to improve patient outcomes. This study utilized a dexamethasone (DEX) and amiodarone (AMIO)-loaded Parylene-C (PPX) nano-structured film to inhibit inflammation and atrial fibrillation. The PPX film was tested in an established pericardial adhesion rabbit model. Following sternotomy, the anterior pericardium was resected and the epicardium was abraded. Rabbits were randomly assigned to five treatment groups: control, oxidized PPX (PPX-Oxd), PPX-Oxd infused with DEX (PPX-Oxd[DEX]), native PPX (PPX), and PPX infused with DEX and AMIO (PPX[AMIO, DEX]). 4 weeks post-sternotomy, pericardial adhesions were evaluated for gross adhesions using a 4-point grading system and histological evaluation for epicardial neotissue fibrosis (NTF). Atrial fibrillation duration and time per induction were measured. The PPX[AMIO, DEX] group had a significant reduction in mean adhesion score compared with the control group (control 2.75 ± 0.42 vs. PPX[AMIO, DEX] 0.25 ± 0.42, P < 0.001). The PPX[AMIO, DEX] group was similar to native PPX (PPX 0.38 ± 0.48 vs. PPX[AMIO, DEX] 0.25 ± 0.42, P=NS). PPX-Oxd group adhesions were indistinguishable from controls (PPX-Oxd 2.83 ± 0.41 vs. control 2.75 ± 0.42, P=NS). NTF was reduced in the PPX[AMIO, DEX] group (0.80 ± 0.10 mm) compared to control (1.78 ± 0.13 mm, P < 0.001). Total duration of atrial fibrillation was decreased in rabbits with PPX[AMIO, DEX] films compared to control (9.5 ± 6.8 s vs. 187.6 ± 174.7 s, p = 0.003). Time of atrial fibrillation per successful induction decreased among PPX[AMIO, DEX] films compared to control (2.8 ± 1.2 s vs. 103.2 ± 178 s, p = 0.004). DEX/AMIO-loaded PPX films are associated with reduced perioperative inflammation and a diminished atrial fibrillation duration. Epicardial application of AMIO, DEX films is a promising strategy to prevent post-operative cardiac complications.

Effect analysis of repeat sternotomy in pediatric cardiac operations

BACKGROUND

Reoperation for congenital heart disease may be associated with cardiac or vascular injuries during repeat sternotomy, resulting in increased mortality and/or morbidity rates. The aim of this study was to determine the frequency of these cardiac injuries and the associated outcome.

METHODS

Between January 2012 and December 2013, 4256 sternotomy procedures were performed at the Pediatric Cardiac Center in Fuwai Hospital, including 195 repeat sternotomy procedures (RS). We retrospectively studied the clinical data of 195 RS patients and 250 randomly selected primary sternotomy (PS) patients. Demographic and operative details, major injures (MI), and clinical outcomes were compared between the two groups. We also assessed the risk factors for major injury and in-hospital mortality and morbidity.

RESULTS

Significant differences were observed between the RS and PS groups in terms of skin incision to cardiopulmonary bypass(CPB) time, overall CPB time, cross-clamp time and blood requirement, and ventilation time (p < 0.001). MI during RS occurred in 7 of the 195 patients (3.6 %), while operative mortality was 1.0 % (2/195). However, in the RS patients, mortality and morbidity rates were not significantly different between the MI subgroup and the non-MI subgroup (p = 1.000 and 0.556, respectively). Additionally, no significant difference was found between the RS and PS groups in terms of mortality (p = 1.000) and morbidity (p = 0.125).

CONCLUSIONS

Both RS and MI are not associated with increased risk of operative mortality and morbidity. Outcomes for reoperative pediatric operations in contemporary practice are similar with those for primary operations.

Binding of Anticell Adhesive Oxime-Crosslinked PEG Hydrogels to Cardiac Tissues

Postsurgical cardiac adhesions increase the number of surgeries as well as patient mortality and morbidity. A fast gelling oxime-crosslinked PEG hydrogel with tunable gelation time, degradation, and mechanical properties is presented. This material is cytocompatible and prevents cellular adhesion. Material retention on different cardiac tissues is demonstrated ex vivo over time and that functional group ratio alters material retention on different cardiac tissues.

Is Seprafilm valuable in infant cardiac redo procedures?

BACKGROUND

Morbidity and mortality are higher for cardiac reoperations than first operation due to the presence of post-operative adhesions. We retrospectively evaluated the efficacy of the bioresorbable membrane Seprafilm to prevent pericardial adhesions after cardiac surgery in a paediatric congenital heart disease population.

METHODS

Seventy-one children undergoing reoperations with sternotomy redo and cardiopulmonary bypass for congenital malformations were included. Twenty-nine of these patients were reoperated after previous application of Seprafilm (treatment group). The duration of dissection, aortic cross clamping and total surgery were recorded. A tenacity score was established for each intervention from the surgeon's description in the operating report.

RESULTS

In multivariate analysis, the duration of dissection and the tenacity score were lower in the treatment than control group (p < 0.01), independent of age and interval since preceding surgery.

CONCLUSION

Our results suggest that Seprafilm is effective in reducing the post-operative adhesions associated with infant cardiac surgery. We recommend the use of Seprafilm in paediatric cardiac surgery when staged surgical interventions are necessary.

Modified Nuss procedure in the treatment of recurrent pectus excavatum after open repair

OBJECTIVES

The purpose of this study was to evaluate the efficacy of the modified Nuss procedure with a subxiphoid incision in correcting recurrent pectus excavatum.

METHODS

From August 2006 to July 2010, 28 patients with recurrent pectus excavatum underwent a secondary repair using the modified Nuss procedure with a subxiphoid incision and bilateral thoracoscopy. Data concerning symptoms, operative course, complications, pulmonary function and early outcome were recorded.

RESULTS

Prior repairs of the reoperation patients included 16 Ravitch, 9 modified Ravitch and 3 sterno-turnover procedures. The median Haller index was 4.52 for the redo patients. Presenting symptoms included decreased endurance, dyspnoea on exertion, chest pain, frequent respiratory infections and palpitations. The median duration of reoperation was slightly longer than that of the primary surgeries. Blood loss and postoperative hospitalization were similar between groups. Complications from pectus reoperations included pneumothorax, pleural effusion, postoperative pain and wound infection in the lateral incision. There were no perioperative deaths or cardiac perforations. Initial postoperative results varied from excellent to good. The patients were followed up for 24-74 months. No steel bar malposition or stabilizer displacement was found in any case.

CONCLUSIONS

The modified Nuss procedure with subxiphoid incision and bilateral thoracoscopy can avoid cardiac injury to the greatest degree. It would be a minimally invasive and safe approach for patients with recurrent pectus excavatum after failed open repair.

A review of the current status of pericardial closure following cardiac surgery

Some cardiac surgeons prefer to close the pericardium whenever possible following surgery, others specifically avoid this practice, and still others believe that neither alternative has any meaningful influence on clinical outcomes. Unfortunately, scientific evidence supporting either approach is scarce, making a consensus regarding best practice impossible. In this article, the known functions of the native intact pericardium are summarized, and the arguments for and against pericardial closure after surgery are examined. In addition, the techniques and materials that have been utilized for pericardial closure previously, as well as those that are currently being developed, are assessed.

Adhesion barrier reduces postoperative adhesions after cardiac surgery

Reoperation in cardiac surgery is associated with increased risk due to surgical adhesions. Application of a bioresorbable material could theoretically reduce adhesions and allow later development of a free dissection plane for cardiac reoperation. Twenty-one patients in whom a bioresorbable hyaluronic acid-carboxymethylcellulose adhesion barrier had been applied in a preceding surgery underwent reoperations, while 23 patients underwent reoperations during the same period without a prior adhesion barrier. Blinded observers graded the tenacity of the adhesions from surgical video recordings of the reoperations. No excessive bleeding requiring wound reexploration, mediastinal infection, or other complication attributable to the adhesion barrier occurred. Multiple regression analysis showed that shorter duration of the preceding surgery, non-use of cardiopulmonary bypass in the preceding surgery, and use of the adhesion barrier were significantly associated with less tenacious surgical adhesions. The use of a bioresorbable material in cardiac surgery reduced postoperative adhesions, facilitated reoperation, and did not promote complications. The use of adhesion barrier is recommended in planned staged procedures and those in which future reoperation is likely.

Prevention of postcardiopulmonary bypass pericardial adhesions by a new resorbable collagen membrane

Reduction in mediastinal adhesions is an issue in cardiac surgery. To evaluate a porcine-bioengineered collagen membrane (Cova™ CARD) intended to promote tissue regeneration, 18 sheep underwent a sternotomy and a 30 min period of cardiopulmonary bypass. They were divided into three equal groups: pericardium left open, placement of an e-polytetrafluoroethylene membrane (Preclude(®)) taken as a non-absorbable substitute comparator and placement of the absorbable Cova™ CARD membrane. Four months thereafter, the study animals underwent repeat sternotomy and were macroscopically assessed for the degree of material resorption and the intensity of adhesions. Explanted hearts were evaluated blindly for the magnitude of the inflammatory response, fibrosis and epicardial re-mesothelialization. The bioengineered membrane was absorbed by 4 months and replaced by a loosely adherent tissue leading to the best adhesion score. There was no inflammatory reaction (except for a minimal one in an animal). Fibrosis was minimal (P = 0.041 vs Preclude(®)). The highest degree of epicardial re-mesothelialization, albeit limited, was achieved by the bioengineered group in which five of six sheep demonstrated a new lining of mesothelial cells in contrast to two animals in each of the other groups. This collagen membrane might thus represent an attractive pericardial substitute for preventing post-operative adhesions.

Bioresorbable adhesion barrier for reducing the severity of postoperative cardiac adhesions: Focus on REPEL-CV(®)

Treatment of a number of congenital heart defects often necessitates staged surgical intervention. In addition, substantial improvements in postoperative cardiac care and more liberal use of biological valve substitutes have resulted in many adult patients surviving to become potential candidates for reoperations to repair or replace valves or to undergo additional revascularization procedures. In all these scenarios, surgeons are confronted with cardiac adhesions, leading to an increased surgical risk. Thus, bioresorbable adhesion barriers had become of increasing interest because they are easy to use, and safe and effective. This review focuses on the mechanisms by which REPEL-CV^® prevents adhesive processes, as well as the development, design, and materials used, and also summarizes efficacy studies, clinical data, safety, and current role in therapy.

Is resternotomy in cardiac surgery still a problem?

Multiple factors contribute to the growing number of reoperations for congenital and acquired cardiovascular diseases in the United States. Although the hazards are well-recognized, the health economic burden of resternotomy (RS) remains unclear and may be difficult to quantify. Contrary to published studies citing low frequencies of catastrophic hemorrhage and mortality, survey responses from practicing surgeons disclose higher rates of complications. Safety strategies in cardiac reoperation have generally involved efforts to maximize visualization during dissection, specialized surgical maneuvers and instrumentation, customized methods for establishing extracorporeal circulation, and techniques to prevent or avoid retrosternal adhesions. Yet, the relative cost-effectiveness of these strategies is largely unexplored. With the ongoing constraints in healthcare budgets, differentiating the value of existing and future approaches in terms of relative clinical benefits, costs, and impact on resource utilization will become increasingly important. We reviewed the relevant published literature in order to survey the morbidity and resource utilization associated with RS in cardiac reoperation and to identify key issues relevant for future studies.

Retrospective review of reoperative pectus excavatum repairs

BACKGROUND/PURPOSE

Despite success of several techniques described for pectus excavatum repair, a minority of patients require multiple reoperations for recurrence or other complications. We aimed to review our experience in reoperative pectus excavatum repairs and to identify features correlating with need for additional reoperations.

METHODS

Charts were reviewed of all patients undergoing reoperative pectus excavatum repair for 3 years at a university-based children's hospital. Number and type of previous repairs, time between operations, lengths of stay, analgesia, and complications were recorded.

RESULTS

From February 2004 to December 2007, 170 pectus excavatum repairs were performed. Among these, 27 were reoperative. Overall, 18.2% of reoperative patients required subsequent additional reoperations. 21.1% of patients undergoing repeat open repairs and 33.3% of patients undergoing repeat minimally invasive repairs required further operative interventions. There was no need for additional repairs among patients who had open repairs after minimally invasive repairs, nor for any patients who had minimally invasive repairs after open repairs.

CONCLUSIONS

We conclude that patients with failed open repairs will have better success with minimally invasive reoperations, whereas patients with failed minimally invasive repairs will have better success with open reoperations. When faced with reoperative pectus excavatum, we recommend consideration of an alternative operative approach from the initial procedure.

A new absorbable collagen membrane to reduce adhesions in cardiac surgery

Reduction of sternal adhesions is still an issue in cardiac surgery. To evaluate a new fibrillar porcine collagen absorbable membrane (Cova CARD), 16 sheep underwent a sternotomy followed by scratching of surface of the heart. They were then divided into three groups: pericardium left opened (n=4), placement of Seprafilm), the reference absorbable substitute (hyaluronic acid and carboxymethylcellulose, n=6) or of Cova CARD membrane (n=6). Four months thereafter, the animals underwent repeat sternotomy and were macroscopically assessed for the degree of resorption of the material and the intensity of adhesions. Explanted hearts were blindly evaluated for the magnitude of the inflammatory response and fibrosis. The Cova CARD membrane was almost totally absorbed by four months and replaced by a loosely adherent tissue. There was no inflammatory reaction and both the extent and density of fibrosis were minimal. The composite score (median [min;max]) integrating tightness of adhesions and histological findings of inflammation and fibrosis was two-fold lower in the Cova CARD than in the Seprafilm) group (2.0 [0;3.5] vs. 5.5 [3;7], P=0.01 by Wilcoxon test). The Cova CARD membrane might represent an attractive pericardial substitute for preventing postoperative adhesions in cardiac surgery.