Comparative study of suture and laser-assisted anastomoses in rat sciatic nerves

Conventional suture repair of peripheral nerves results in a fibrotic reaction that is detrimental to nerve regeneration. As an alternative procedure known as "laser-assisted" repair, a laser can be used, along with a reduced number of sutures, to reanastomose served peripheral nerves. To explore the long-term implications of this technique, the right sciatic nerves of Sprague-Dawley rats were surgically cut and reanastomosed either by means of four epineurial sutures or two epineurial sutures and CO2 laser welds. Tensile strength, electrophysiology, histology, and functional studies were performed up to 11 months postoperatively. Tensile strength measurements indicate no long-term disadvantage with the laser-assisted technique, although the short-term tensile strength is lower than with conventional suture repair. The conduction velocities of the repaired nerves were similar for both techniques; however, laser-assisted repaired nerves were found to have lower stimulation thresholds and reduced branching compared to the suture repaired nerves. The measured functional recovery was similar for both repair techniques.     

A controlled comparison one- and two-layer techniques of suture for high and low colorectal anastomoses.

A controlled trial of one- and two-layer inverting techniques of sutures for the contruction of high and low colorectal anastomoses was conducted on 137 patients, the integrity of the suture lines being assessed clinically and by routine radiological examination after a small Gastrografin enema. A clinical diagnosis of anastomotic leakage was made in 9 patients (or perhaps more accurately in 5 only), but subclinical dehiscence was demonstrated radiologically in a further 39 patients (or perhaps 43). There was a slightly greater incidence of dehiscence after the one-layer technique of suture for both high and low anterior resection.     

CO2 and Nd:YAG laser systems in microsurgical venous anastomoses

Summary A comparative study was undertaken in 81 rats to investigate a CO₂ and Nd:YAG laser system for laserwelded anastomosis of the femoral vein. Conventionally sutured anastomoses (CMSA) served as controls. Laserwelded anastomosis (LAMA) was easier and could be performed 30% faster than CMSA. Postoperative investigations included patency tests, postmortem examinations and light and electron microscopy. Aneurysms were not seen. Foreign-body reaction was more pronounced in CMSA. Patency rates for CO₂-LAMA and CMSA were equal, whereas Nd:YAG-LAMA resulted in significantly higher rate of early postoperative thrombosis (P<0.01). Because of its physical properties, the CO₂-laser system seems to be better suited for laser welding of delicate structures such as the rat femoral vein.     

Bursting strength of the rat aorta: comparison of suture and laser anastomoses

The bursting strength of sutured and laser-welded vascular anastomoses were assessed in a rat aorta model. Postoperative investigations included postmortems, light and scanning electron microscopy and measurements of bursting strength at set intervals (30 min, 3, 14 and 28 days postoperatively, p.o.). Laser-bonded anastomoses consistently demonstrated lower bursting strengths than suture controls, with statistically significant differences at 30 min and 3 days p.o. (p less than 0.01). Laser anastomosis was easier and faster to perform, the foreign body reaction was markedly lower than in sutured controls. Formation of aneurysms was not observed.     

CO2 and argon laser vascular welding: acute histologic and thermodynamic comparison

CO2 and argon lasers have been used successfully for vascular welding in both experimental and clinical settings. This study compared the thermodynamics during CO2 and argon laser welding of 1-cm longitudinal arteriotomies in a canine model. Continuous recordings using an AGA 782 digital thermographic system with spatial and thermal resolution of +/-0.2 mm and +/-0.2 degree C, respectively, were analyzed. A HGM argon laser using a 300-microns optic fiber held at 1 cm from the vessel edges (spot diameter = 2.8 mm) with concomitant room temperature saline irrigation (1 drop/sec) was used for argon welds. Total exposure time was 150 sec/cm. CO2 welds were performed with a Sharplan CO2 laser (spot diameter = 0.22 mm) with no irrigation for total exposure time of 10 sec/cm. Thermodynamic results and laser parameters are summarized as follows: Argon-n = 20; power = 500 mW; energy fluence = 1,400 J/cm2; Tmax = 48.8 degrees C; T mean +/- S.D. = 45.1 +/- 2.7 degrees C; CO2-n = 20; power = 150 mW; energy fluence = 3,000 J/cm2; Tmax 84.0 degrees C; T mean +/- S.D. = 60.7 +/- 9.8 degrees C. There was a significant difference (P less than .05) in thermal measurements between successful CO2 and argon vascular welds. Temperature rise during the argon welds was limited by saline irrigation. In contrast, during CO2 laser welding, the temperature rose quickly to its maximum and was maintained at a relatively high level as the laser progressed (0.1 cm/sec) along the anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Absorbable polydioxanone suture for venous anastomoses: experimental studies using venography and transluminal angioscopy

Because of their increased tendency to stenosis and spasm and thrombosis, results after venous anastomoses are often unsatisfactory. Nonabsorbable sutures and a continuous suture technique have been suggested to have a negative effect on the compliance of vascular anastomoses. Eighty venous anastomoses were performed with either an interrupted or continuous suture technique, using polypropylene or polydioxanone (PDS) sutures, according to a randomised experimental model. The anastomoses were divided in four groups: (1) Nonabsorbable suture material, continuous suture technique; (2) Nonabsorbable suture material, interrupted suture technique; (3) Absorbable suture material, continuous suture technique; and (4) Absorbable suture material, interrupted suture technique. The morphology of the anastomoses was controlled by venography directly after closure of the wound and at weekly intervals for 2 months and monthly intervals thereafter until 2 years had passed. In 10 cases venography was followed by transluminal angioscopy in the early postoperative period and after 1, 2, 4, 8 and 12 weeks. In the first 2 months moderate and high degree stenoses were found in all 4 groups by venography. After 8 weeks there was a significant decrease in the incidence of stenosis in all groups with the exception of the group, in which continuous nonabsorbable suture had been used. Using angioscopy a marked swelling of the intima at the site of the anastomoses could be detected in the early postoperative period in all experimental groups. After 2 months no significant narrowing could be identified in groups 2, 3 and 4.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative study of microepineurial anastomoses with the use of CO2 laser and suture techniques in rat sciatic nerves: Part 1. Surgical technique, nerve action potentials, and morphological studies

The possibility of utilizing the CO2 laser for neural anastomoses was investigated in a rat sciatic nerve model. One nerve in each animal was acutely divided and anastomosed using 10-0 nylon epineurial sutures, while the opposite side was joined by "welding" the opposed nerve ends together with CO2 laser pulses. The surgical incisions were reexplored 60 days postoperatively, action potentials were recorded across the anastomoses, and the nerves were removed for light and electron microscopy. The operative patency rate in the suture group was 100%, compared to 87% in the laser group. Among those animals with bilaterally intact nerves, action potentials could be recorded across the anastomotic site in 78% of the sutured preparations and in 85% of nerves spot-welded with the CO2 laser. Morphological studies showed a greater degree of scar tissue formation and constriction in the anastomotic zone of the nerves joined by sutures than was present in laser-treated animals. We believe these preliminary observations suggest that the CO2 laser may have a role to play in peripheral nerve surgery. Further study of this technique is warranted.     

The morphology and patency of arterial and venous microvascular anastomoses throughout the first post-operative year. A histological study

End-to-end microvascular suture anastomoses, 40 arterial and 41 venous, from the rabbits carotid artery and posterior facial vein were harvested at 5 different time intervals (1, 2, 3, 6 and 12 months) post surgery and evaluated with light microscopy. A 100% long-term patency was noted both in arteries and veins. Quantitative measurements of the width of the vessel wall components indicated that a statistically significant temporary hypertrophic response occurred in the arterial intima, culminating in the third month when the width of the vessel wall at the anastomotic level almost doubled the normal. After that the width of the vessel wall again declined but it remained thicker than the adjacent vessel wall at one year post surgery. Among the venous anastomoses, however, the wall thickness at the anastomotic level remained thinner than the adjacent vessel wall throughout the evaluation period. The original vessel wall characteristics are not restored at the anastomotic site with intimal hyperplasia compensating for medial necrosis. Despite these events a technically satisfactory microvascular anastomosis should remain patent for years.     

Single or double layer? A controlled prospective study on the comparison of 2 suture technics in gastrointestinal anastomoses

In a controlled clinical trial in 165 patients single layer anastomoses (n = 103) were compared to two layer anastomoses (n = 62). All anastomoses were controlled radiologically. The rate of dehiscence was 7.7% (n = 8) for the single layer group, 6.5% (n = 4) for the two layer group. Six patients died, 3 of both groups (2.9%:4.8%). There was no significant difference. However, for gastrectomies and anastomoses of small and large bowel single layer anastomoses seem to be preferable, for partial gastric resection two layer anastomoses. Factors predisposing for anastomotic breakdown are: age beyond 50, colo-rectal anastomoses, protein levels beyond 6 mg%, carcinosis peritonei.     

2-octylcyanoacrylate-assisted microvascular anastomosis: comparison with a conventional suture technique in rat femoral arteries

Standard microvascular anastomosis using only sutures is a well-established and successful technique; however, it is time-consuming and may cause vessel narrowing, needle trauma, and tissue reaction. The authors' hypothesis was that 2-octylcyanoacrylate could simplify microvascular anastomosis and reduce wall trauma and reaction. End-to-end anastomoses of the femoral arteries were performed in 20 adult rats. Each animal served as its own control. The time taken for each anastomosis (from first stitch to release of clamps) was noted, and the patency assessed. At day 7, the anastomoses were reassessed for patency, and the vessels evaluated histologically. 2-octylcyanoacrylate reduced the need to insert more sutures. Anastomotic time in the study group was statistically significantly shorter (p < 0.001), and the patency rate was 90 percent, compared to 85 percent with the standard suture technique. There was also less intense inflammatory reaction, with fewer foreign-body granulomata. This is the first report on the use of 2-octylcyanocrylate, currently approved for cutaneous use, for vessel anastomosis. Further work on the biomechanics and long-term histologic effects will be carried out. 2-octylcyanoacrylate has the potential for simplifying and improving the patency rates of arterial microanastomosis.     

CO2 laser-assisted microvascular anastomosis: biomechanical studies and clinical applications

Experiments have been performed using CO2 laser-assisted microvascular anastomoses, and they demonstrated the following features, in comparison with conventional anastomoses: ease in technique; less time consumption; less tissue inflammation; early wound healing; equivalency of patency rate and inner pressure tolerance; but only about 50 percent of the tensile strength of manual-suture anastomosis. Six clinical applications in 16 vessels are reported, using this procedure. The preliminary results of these cases would appear to be the first successful replantations and free tissue transfers using CO2 laser-assisted microvascular anastomoses in man. The procedure offers increased safety and speed in microvascular anastomoses.