Prevention of postoperative pericardial adhesions in children with hypoplastic left heart syndrome

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.

Prospects for prevention of adhesion process during cardiac surgical interventions

The article is devoted to the problem of prevention of adhesions in cardiac surgery. It was determined that the problem is urgent due to the increase in the number of heart surgeries. The formation of adhesions is a reaction of the body after surgery, which is a stage of healing and partly performs a protective function. Nevertheless, the presence of adhesions violates the mechanical properties of the heart, negatively affects central hemodynamics, complicates the surgeon’s task during repeated surgical interventions and increases the risk of repeated operations.It has been shown that at present, for the prevention of adhesions, researchers tend to use biodegradable barrier materials with biocompatibility and the ability to dissolve after performing the barrier function. The main anti-adhesion agents used in cardiac surgery are membranes and gels. The requirements for an “ideal” agent for the prevention of adhesion were determined: biocompatibility, no irritating effect, no effect on wound healing, suppression of the growth of connective tissue in the pericardium.Conclusions. Until now, none of the funds has all the necessary qualities to prevent adhesion in the pericardium. Therefore, the search for effective methods for the prevention of postoperative adhesions remains relevant for cardiac surgery.

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.

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.

Battling adhesions: from understanding to prevention

Adhesions represent a major burden in clinical practice, particularly following abdominal, intrauterine, pericardial and tendon surgical procedures. Adhesions are initiated by a disruption in the epithelial or mesothelial layer of tissue, which leads to fibrin adhesion sites due to the downregulation of fibrinolytic activity and an increase in fibrin deposition. Hence, the metabolic events involved in tissue healing, coagulation, inflammation, fibrinolysis and angiogenesis play a pivotal role in adhesion formation. Understanding these events, their interactions and their influence on the development of post-surgical adhesion is crucial for the development of effective therapies to prevent them. Mechanical barriers, antiadhesive agents and combination thereof are customarily used in the battle against adhesions. Although these systems seem to be effective at reducing adhesions in clinical procedures, their prevention remains still elusive, imposing the need for new antiadhesive strategies.

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.

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.

Longer-term issues for young adults with hypoplastic left heart syndrome: contraception, pregnancy, transition, transfer, counselling, and re-operation

Hypoplastic left heart syndrome remained a largely untreated lesion until the 1980s. In the current era, 75-80% of patients who are managed at "centres of excellence" can be expected to survive into young adulthood after staged palliation. This improved survival has led to an emerging population of patients now entering adulthood with a new set of concerns. We discuss the realised and potential issues that will be faced by these patients, including family planning, transition, and re-operation.