Tenacity Of Adhesions Research Articles

Aortic Valve Replacement for Aortic Stenosis During Orthotopic Cardiac Transplant

Although concomitant coronary bypass, and mitral and tricuspid valve surgery have been used to expand the donor pool for cardiac transplantation, aortic valve disease is considered an absolute contraindication for use of an offered organ. A case is presented with the successful use of an organ requiring concomitant aortic valve replacement for calcific aortic stenosis on a congenitally bicuspid valve. Eighteen-month follow-up documented excellent allograft function with a normally functioning mechanical aortic prosthesis. Aortic valve disease in offered organs can be successfully treated with aortic valve replacement at the time of transplantation and should not preclude the use of the organ in the setting of a recipient who is a candidate for a marginal allograft.

QS69. Two Experimental Models for Generating Abdominal Adhesions

Purpose: Students of experimental adhesion methodology have regularly noted discrepant results between laboratories, probably attributable to variable Methods for inducing adhesions and to different criteria for quantifying results. The purpose of these experiments was to develop dependable rat models for generating abdominal adhesions that allow for objective evaluation and quantification. Methods: Two new adhesion models were compared with classical side-wall models involving cecal abrasion and peritoneal excision or abrasion. Cecal Abrasion: The cecum was exteriorized and the medial surface abraded with dry gauze over a 1 by 2 centimeter area. A similar area of the adjacent side-wall peritoneum was abraded or was excised, leaving the underlying muscle exposed. MODEL T (tissue): a 2.5 by 2.5 cm segment of full-thickness abdominal wall was excised and the overlying skin incision closed, exposing the viscera to subcutaneous tissue; MODEL M (mesh): involved removal of an identical segment, replacing the defect with a 2.5 by 2.5 cm polypropylene mesh sewn to the cut edges. This exposed the viscera directly to the mesh surface. Seven days after operation the character and extent of the adhesions were assessed at autopsy. Results were expressed as the percent area of subcutaneous tissue involved (T) or of mesh surface involved (M). For model T the percent involvement of the circumference of the defect edge was also recorded. The extent of omental and intestinal adhesions were evaluated individually. Results: The classical side-wall models showed inconsistent patterns of adhesion formation and were difficult to evaluate. Every animal from both models M and T developed extensive adhesions. The mean coverage of mesh surface (M) was 93 percent and subcutaneous surface (T) 82 percent. In model T the mean involvement of the defect cut edge was 80 percent of the circumference. All model T animals had both intestinal and omental adhesions. Tenacity of adhesions did not differ significantly between animals or models. Conclusions: Adhesion models M and T are consistent and predictable. Each yields extensive adhesion coverage of a defined two dimensional site which allows for standardized measurement. Adhesion quality varies little among animals with these preparations. The relative ease of preparation and of assessment should make for ready comparison among laboratories and credible results regarding prevention strategies. Tabled 1Adhesion Involvement Adhesions to abdominal wall Adhesions to cecum Mean mesh or SQ surface, % area Mean cut edge, % circumference Structure(s) adhered Small bowel Omentum Cecal Abrasion + Peritoneal Abrasion 50% (7/14) 50% (7/14) NA NA 4 5 Cecal Abrasion + Peritoneal Excision 59% (13/22) 73% (16/22) NA NA 5 14 Model M NA NA 93% (39/39) NA 0 39 Model T NA NA 82% (15/15) 80% 15 15 SQ: subcutaneous, NA: not applicable. Open table in a new tab SQ: subcutaneous, NA: not applicable.

Two Experimental Models for Generating Abdominal Adhesions

To develop dependable rat models for generating abdominal adhesions that allow for objective evaluation and quantification. Two adhesion models were devised and compared with conventional side-wall models involving cecal abrasion and peritoneal excision or abrasion. model T (tissue): removal of a 2.5 by 2.5 cm segment of full-thickness abdominal wall with overlying skin closure, exposing the viscera to subcutaneous tissue; model M (mesh): removal of an identical segment, replacing the defect with a 2.5 by 2.5 cm polypropylene mesh sewn to the cut edges. This exposed the viscera directly to the mesh surface. Seven days after operation, the character and extent of the adhesions were assessed at autopsy. Results were expressed as the percent area of subcutaneous tissue involved (T) or of mesh surface involved (M). For model T the percent involvement of the circumference of the defect edge was also recorded. The extent of omental and intestinal adhesions were evaluated individually. The classical side-wall models showed inconsistent patterns of adhesion formation and were difficult to evaluate. Every animal from both models M and T developed extensive adhesions. The mean coverage of mesh surface (M) was 93% and subcutaneous surface (T) 82%. In model T the mean involvement of the defect cut edge was 80% of the circumference. All model T animals had both intestinal and omental adhesions whereas there were no intestinal attachments in model M. Tenacity of adhesions did not differ significantly between animals or models. Adhesion models M and T are consistent, predictable, and dependable. They each yield extensive adhesion coverage to a defined site, which allow for standardized measurement.

Polyglycolic Acid Glue Does Not Prevent Intrapericardial Adhesions in a Short-Term Follow-Up

Pericardial adhesions are a significant challenge for reoperative cardiac surgery. There are no established means of prevention. Lately, sprayable glues have been suggested to inhibit and reduce adhesion formation in congenital heart surgery, where repeated cardiac operations are often needed. In this study, we tested a novel, synthetic, sprayable, and resorbable polyglycolic acid glue (DuraSeal; Confluent Surgical, Inc., Waltham, MA) that has been approved by the United States Food and Drug Administration as a dural sealant. A standard sternotomy and longitudinal pericardiotomy was performed in seven pigs, and polyglycolic acid glue (DuraSeal) was administered randomly on either side of the heart. The pericardium was sutured and autologous blood was instilled into pericardium to augment adhesion formation. After 6 wk, the hearts were photographed and examined in terms of adhesion formation (tenacity, extension, and strength), and visibility of the coronary vessels. A semiquantitative scale 0-3 was used. All animals produced significant pericardial adhesions. There were no statistically significant differences in tenacity, extension, or strength of adhesions between glued and non-glued sides of the hearts, nor was there any significant variation in the visibility of the coronary vessels between the sides. The DuraSeal polyglycolic acid glue did not reduce the development of pericardial adhesions in pigs.

Evaluation of adhesion formation, mesh fixation strength, and hydroxyproline content after intraabdominal placement of polytetrafluoroethylene mesh secured using titanium spiral tacks, nitinol anchors, and polypropylene suture or polyglactin 910 suture

The purpose of this study is to evaluate fixation methods for polytetrafluoroethylene (ePTFE) mesh with an in vivo model of laparoscopic ventral hernia repair. In 40 New Zealand white rabbits, a 4 x 4-cm ePTFE mesh (n = 80, two per animal) was attached to an intact peritoneum with polyglactin 910 (PG 910) (n = 20) or polypropylene (PP) (n = 20) suture, titanium spiral tacks (TS) (n = 20), or nitinol anchors (NA) (n = 20). Mesh was harvested at 8 and 16 weeks for fixation strength testing, adhesion assessment, and collagen (hydroxyproline) content. Fixation strength on day 0 was determined with mesh attached to harvested abdominal wall. Statistical significance was determined as p < 0.05. There was no difference in fixation strength between PP (39.1 N) and PG 910 (40.0 N) sutures at time zero. At week 8, PP (25.7 N) was significantly stronger (p < 0.05) than PG 910 (11.4 N) suture, but not at week 16. The fixation strength of TS and NA (day 0, 15.4 vs 7.4 N; week 8, 17.5 vs 15.3 N; week 16, 19.1 vs 13.8 N) was not significantly different. Fixation with PP suture was significantly (p < 0.05) stronger than that with TS and NA at day 0 (39.1, 15.4, and 7.4 N, respectively) but not at weeks 8 or 16. The fixation strength of suture decreased significantly (p < 0.05) from day 0 to week 16 (PP: day 0 = 39.1 N, week 8 = 25.7 N, week 16 = 21.4 N; PG 910: day 0 = 40.0 N, week 8 = 11.4 N, week 16 = 12.8 N). The fixation strength of NA and TS did not change significantly (NA: day 0 = 7.4 N, week 8 = 15.3 N, week 16 = 13.8 N; TS: week 0 = 15.4 N, week 8 = 17.5 N, week 16 = 19.1 N). There were no differences in adhesion area based on fixation device used; however, there were more (p < 0.05) mesh samples using NA with adhesions compared to TS and adhesion tenacity was greater (p < 0.05) compared to that of TS, PP, and PG. Hydroxyproline content at weeks 8 and 16 was similar for all fixation devices. The initial fixation strength for nonabsorbable suture is significantly greater than that of the metallic fixation devices, but after 8 weeks there is no difference. Laparoscopic ventral hernia repair without transabdominal suture fixation may be predisposed to acute failure. The metallic devices have similar fixation strength, although the incidence of adhesions and tenacity of adhesions appear to be greater with the nitinol anchors. Since these devices have similar fixation strengths and most likely provide adequate supplementation to transabdominal sutures for mesh fixation after laparoscopic ventral hernia repair, their use should be based on other factors, such as their propensity for adhesions, ease of application, and cost.

A novel adhesion barrier facilitates reoperations in complex congenital cardiac surgery

Reoperations are associated with an increased surgical risk due to adhesions. We prospectively evaluated a bioresorbable membrane after surgery for congenital heart defects over a 3.5-year period. The surgical membrane (CV Seprafilm, Genzyme, Cambridge, Mass) was applied in 350 of 1024 patients; 30 of them underwent reoperation and were evaluated in comparison to 10 random reoperated patients. Adhesions were evaluated using a subjective scoring system [1 (lowest tenacity) to 5 (highest tenacity)] and extent in percent at different regions of the heart. Patients were operated for atrioventricular septal defect (69), tetralogy of Fallot (65), functional single ventricle (75), valve surgery (48), ventricular septal defect (20), subaortic stenosis (17), hypoplastic left heart syndrome (17), and other diagnoses (39). Application of the surgical membrane was safe in all patients, without any infections. At reoperation patients received Glenn (14), total cavopulmonary connection (6), and others (10). Overall mortality was 2/350 (0.57%). There was a remarkable reduction in tenacity score (3.3 vs 4.3) and in the extent of adhesions (77.7% vs 86%). Duration of reoperation was significantly reduced. A bioresorbable surgical membrane leads to a significant reduction in the tenacity and amount of adhesions. It is recommended for general use whenever repeat operation is anticipated in congenital as well as in adult cardiac surgery.

Next-generation hydrogel films as tissue sealants and adhesion barriers.

The development of conveniently sprayed, tissue-adherent, inert hydrogel films has made possible the creation of novel products that can serve a dual function, as a surgical sealant to achieve immediate hemostasis, and as a barrier to prevent adhesion formation over time. A sprayable, in situ formed absorbable hydrogel film was evaluated as a tissue sealant in a heparinized canine carotid artery graft model. PTFE grafts with leaking end-to-side anastomoses were treated with the synthetic sealant, and hemostasis was evaluated upon restoration of blood flow. Also, the hydrogel films were evaluated as an adhesion barrier in a rabbit pericardial abrasion model. The sprayable, in situ forming hydrogel film was shown to immediately seal carotid-PTFE anastomoses in six of six applications. Hydrogel application in a rabbit pericardial abrasion model resulted in a statistically significant reduction in the number and tenacity of adhesions. This novel in situ formed sprayable hydrogel film has demonstrated a dual function as an effective tissue sealant and as an adhesion barrier in cardiovascular preclinical models. These next generation synthetic biomaterials are currently undergoing clinical investigations.

Reducing the incidence and severity of pericardial adhesions with a sprayable polymeric matrix

Purpose This study was undertaken to evaluate the antiadhesive properties of a polymeric agent in infants undergoing staged surgical correction of congenital heart abnormalities. Description Sixteen infants having staged surgical repair were treated with a polymeric matrix at the completion of the initial surgery. There were 5 untreated controls. The tenacity and extent of adhesions at five separate regions of the heart were evaluated at the follow-up surgery. Evaluation For all sites combined, there was a threefold difference in median tenacity scores in favor of the experimental treatment (1.0 vs 3.0, p < 0.01). Significant differences were achieved separately at the right ventricle and the anterior surface of the great vessels ( p = 0.02 for both comparisons). Analysis of adhesion scores reflecting the extent of adhesions similarly favored the experimental treatment for all sites (80 vs 270, p < 0.01), with significant differences persisting at the right atrium ( p < 0.01) and the anterior surface of the great vessels ( p = 0.04). There were no treatment-related adverse events. Conclusions Use of this polymeric agent at the completion of open cardiac surgery may prevent the occurrence or reduce the severity of pericardial adhesions.

Experimental study of adhesion formation in open and laparoscopic fundoplication.

The extent of adhesion formation following both open and laparoscopic surgery remains unclear. This study aimed to evaluate the extent of postoperative adhesion formation after laparoscopic and open fundoplication in a rat model. Fifty-two male Sprague-Dawley rats were randomized into four groups: laparoscopic fundoplication (n = 20), open fundoplication (n = 20), laparoscopy (n = 6) and laparotomy (n = 6). Blood as well as intraperitoneal fluid was sampled for tumour necrosis factor (TNF) alpha measurement by enzyme-linked immunosorbent assay. All the rats were killed 3 weeks after operation, and adhesion formation was evaluated using a standardized scoring system. There were no intergroup differences in body-weight gain after surgery. The overall mortality rate was 19 per cent and death was observed only in the fundoplication groups. Animals that had open fundoplication developed significantly more adhesions than those that underwent laparoscopic fundoplication (34 versus 21). Laparoscopic surgery induced predominantly parietal adhesions, whereas open surgery was more associated with visceral adhesions. The adhesions observed in the laparoscopic groups were significant thinner than those after open surgery and the tenacity of adhesions was decreased in laparoscopic compared with open surgery. The peak plasma level of TNF-alpha was reached during laparoscopic fundoplication, whereas the peak level was observed 3 h after open fundoplication. Intraperitoneal TNF-alpha levels showed no significant differences at 3 h. These findings indicate that laparoscopic fundoplication in rats leads to less severe adhesions of a different type (parietal) compared with those seen in the open controls.

Role of a hyaluronate-based membrane in the prevention of peritonitis-induced adhesions

Adhesions remain a significant postoperative complication of abdominal surgery; however, recent evidence suggests that physical barriers may reduce their incidence. Although these adhesion prevention barriers are efficacious when used under aseptic conditions, little is known about their use in the presence of peritonitis, which is associated with an increased incidence of abdominal adhesions. A sodium hyaluronate and carboxymethylcellulose bioresorbable membrane (HA membrane) has been shown recently to reduce postoperative adhesions in several animal models and in two clinical trials. To investigate the efficacy of HA membrane in the presence of peritonitis, generalized peritonitis was induced in rats by either cecal ligation and puncture (CLP) or cecal ligation (CL) alone. The ceca were resected after 12 hours, and animals were randomly assigned to receive or not receive HA membrane applied to the cecum. At day 7, abdominal adhesions and abscesses were scored. In the presence of peritonitis, HA membrane did not significantly reduce the number or tenacity of adhesions. A trend toward increased abscess formation was associated with HA membrane in the CL group. Although HA membrane has been shown to reduce the incidence and severity of abdominal adhesions under aseptic conditions, this study demonstrates that it is not efficacious in preventing abdominal adhesions in the presence of peritonitis. The association between HA membrane and abscess formation in the presence of experimental peritonitis requires further investigation.