In-vivo evaluation of a reinforced ovine biologic: a comparative study to available hernia mesh repair materials.

PURPOSE: Two innovative reinforced biologic materials were studied in a non-human primate hernia repair model. The test articles, which combine layers of ovine decellularized extracellular matrix with minimal amounts of synthetic polymer, were evaluated for their biologic performance as measured by inflammatory response, healing kinetics, integration, and remodeling into functional host tissue. For comparison, seven clinically used biologic and synthetic meshes were also studied. METHODS: Animals were implanted with test articles in surgically created full-thickness midline abdominal wall defects, and evaluated macroscopically and histologically at 4, 12, and 24 weeks. RESULTS: Macroscopically, biologics resorbed and remodeled into naturally appearing tissue; the reinforced biologics appeared similar, but remodeled earlier and were less prone to stretch. Synthetics developed a layer of reactive tissue above and separate from the contracted mesh structure. At early time points, the collagen networks of biologics and reinforced biologics were infiltrated by host cells primarily as a peripheral layer on the biologics. As early as 12 weeks, the collagen networks associated with the reinforced biologics remodeled into organized host collagen. By 24 weeks, both reinforced biologics and biologics had low levels of inflammation. In contrast, a foreign body response persisted at 24 weeks with the synthetics, which had developed less organized collagen, separate in space from the actual mesh. CONCLUSIONS: The current study shows a favorable response to reinforced biologics, which were associated with an initial inflammatory response, resolving by later time points, followed by active remodeling, and the formation of new morphologically functional collagen.

Dynamic aortomyoplasty: clinical experience and thoracoscopic surgery feasibility study.

BACKGROUND: Surgical procedures using the latissimus dorsi (LD) muscle to assist chronic heart failure inflict major trauma on severely sick patients. A less invasive approach may prove beneficial. The aim of this article is to review our clinical and experimental approaches of dynamic aortomyoplasty (AMP) and emphasize the necessity to reorient surgical technique towards new directions and a less invasive thoracoscopic approach. MATERIALS AND METHODS: A clinical pilot study on dynamic descending AMP started in June 1995 and included four patients. Two of them could benefit from LD counterpulsation, surviving 6 months and 18 months. Following this clinical experience, we investigated, on an animal model, minimally invasive thoracoscopic surgery for this procedure. Twelve goats underwent endoscopic LD harvest and video-assisted aortic wrap, and were studied after surgical recovery from an anatomical and functional standpoint. RESULTS: Clinical AMP using open techniques provided extraaortic counterpulsation in NYHA Class IV patients contraindicated for other surgical therapies. However, surgical technique and strategy needed improvements for optimal cardiac assistance and better patient outcome. Minimally invasive thoracoscopic surgery was feasible and reproducible in goats, achieving improved anatomy and physiology as compared to the open technique in humans. When appropriate the wrapping technique and stimulation protocol were used, an optimal counterpulsation was demonstrated. We concluded that thoracoscopic AMP may provide a minimally invasive approach to cardiac assistance and thus, a new surgical option for patients presenting with chronic heart failure.

Innovative techniques in skeletal muscle cardiac assistance: first experimental study on minimally invasive aortomyoplasty and cardiomyoplasty.

Skeletal muscle cardiac assistance as a treatment modality for heart failure is considered a high-risk procedure subject to strict patient selection. The aim here is to develop minimally invasive techniques to improve surgical outcomes and increase clinical indications. Ten goats (45-55 kg) were studied. In six, the latissimus dorsi muscle (LDM) was harvested via an open technique on one side vs a minimally invasive technique on the other using video assistance through two 3 cm incisions. Surgical maneuvers and length of procedures were noted. Animals were recovered, observed daily for local complications, and killed after 1 week for comparative anatomic and histopathologic studies. In four other goats, minimally invasive aortomyoplasty or cardiomyoplasty was performed using video assistance (2 aortomyoplasty, 2 cardiomyoplasty). In this experimental series, there were no surgical complications. The minimally invasive LDM harvest required a mean of 81 min (range 55-116 mn) with no gross evidence of muscle damage. The technique of LDM harvesting was standardized and is reproducible. Aortic and cardiac wraping were also achieved through three ports and a left minithoracotomy of 4 cm, using the right or left LDM. A scarf technique for the descending aortomyoplasty using the left LDM, and an anterior wrapping for cardiomyoplasty using the left or right LDM was technically feasible with video assistance. This study suggests future clinical applicability.

Extent of smooth muscle resection during mucosectomy and ileal pouch-anal anastomosis affects anorectal physiology and functional outcome.

PURPOSE: In patients undergoing colectomy with ileal pouch-anal anastomosis, controversy exists regarding the necessity for and appropriate extent of rectal mucosal resection. Our aim was to assess histologically the extent of anorectal smooth muscle resected at the time of mucosal proctectomy and to correlate this with postoperative bowel and anal sphincter function. METHODS: Surgical specimens of 79 patients undergoing colectomy, mucosal proctectomy, and ileal pouch-anal anastomosis were examined histologically in a blinded fashion, and the content of smooth muscle in the mucosal proctectomy specimens was scored. Degree of smooth muscle resection was correlated with postoperative anorectal manometry and with functional outcomes, including stool frequency and nocturnal leakage of stool after 3 and 12 months of follow-up. RESULTS: Degree of smooth muscle loss correlated with decreased resting pressure of the internal anal sphincter as early as three months after surgery (r = -0.26; P = 0.03), and the correlation was even stronger after 12 months (r = -0.37; P = 0.005). Decreases in resting pressure were related, in turn, to increased stool frequency at 12 months (r = 0.32; P = 0.02), but stool frequency was also inversely related to volume of the ileal pouch (r = -0.27; P = 0.05). Multivariate analysis confirmed that resting pressure and pouch volume were both significant determinants of stool frequency. The likelihood of nocturnal stool leakage at 12 months was primarily a function of stool frequency (P < 0.01) but also increased with patient age (P < 0.02). CONCLUSIONS: These findings indicate that loss of resting pressure of the internal anal sphincter can be correlated with the extent of smooth muscle resection during rectal mucosectomy and that these factors, in turn, correlate with increased stool frequency and a greater likelihood of nocturnal stool leakage. Consequently, an optimum functional result requires care in identifying and preserving maximum anorectal smooth muscle during mucosectomy.

Does aggressive medical therapy for acute ulcerative colitis result in a higher incidence of staged colectomy?

BACKGROUND: Colectomy with ileal pouch-anal anastomosis is the operation of choice in patients with medically refractory ulcerative colitis. However, aggressive or prolonged medical treatment may result in the patient's needing an urgent operation in which a staged subtotal colectomy is necessary. OBJECTIVE: Our hypothesis is that the incidence of patients requiring a staged approach has increased, along with an increase in hospital stay and total hospital costs. DESIGN: We examined the medical records of 250 consecutive patients with ulcerative colitis who underwent ileal pouch-anal anastomosis between 1984 and 1993. RESULTS: Simultaneous colectomy and ileal pouch-anal anastomosis were performed in 196 patients (78%), while 54 patients (21.6%) required staged subtotal (78%) or partial colectomy (22%). Indications for initial colectomy included failure of medical therapy (42 patients [77.8%]), undifferentiated colitis (five patients [9.3%]), and perforation (six patients [11.1%]). An increase in the incidence of patients requiring staged colectomy during this period was observed (P < .05). Staged procedures led to a prolonged hospital course at a significantly greater total cost. CONCLUSION: We conclude that aggressive medical therapy of acute ulcerative colitis has increased the incidence of urgent staged colectomy with a resulting increase in morbidity, hospital stay, and cost and a less-optimal functional result.

Counterregulation of a prokinetic calcium-dependent mechanism by cAMP-dependent agents in isolated segments of terminal ileum.

The ill-understood complex of the irritable bowel syndrome comprises a group of intestinal motility disorders characterized by increased intraluminal pressures and decreased transit times. Elucidation of mechanisms which modulate gut motility may lead to the development of rational therapy for this prevalent problem. The purpose of this study was firstly to evaluate the interaction of cAMP-dependent agents (vasoactive intestinal polypeptide (VIP), norepinephrine (NE), and forskolin (FK)) on carbachol (Ca2+)-initiated motility and secondly to determine if a neural component of motility modulation existed by testing if the effect of cAMP-dependent agents was reversed by tetrodotoxin-induced neural blockade. Motility was measured in isolated segments of terminal ileum harvested from rabbits using perfusion manometry and quantitated by integration, expressed as mm Hg/min. Carbachol caused a concentration-dependent increase in measured motor activity (half-effective dose = 10(-7) M). VIP, NE, and FK each caused a concentration-dependent inhibition of carbachol-stimulated phasic contractions. TTX 10(-6) M failed to block the inhibitory actions of NE. In conclusion, these results suggest that cAMP-dependent mechanisms may inhibit gut motility induced by a cholinergic (Ca2+)-mediated agonist and that this process is mediated by a nonneural mechanism.