A comparison of para-anastomotic compliance profiles after vascular anastomosis: nonpenetrating clips versus standard sutures

PURPOSE: Anastomotic compliance is an important predictive factor for long-term patency of small diameter vascular reconstruction. In this experimental study we compare the compliance of continuous and interrupted sutured vascular anastomoses with those using nonpenetrating clips. METHODS: Both common carotid arteries in nine goats (average weight, 57 +/- 5.7 kg) were transected, and end-to-end anastomoses were constructed with nonpenetrating clips or polypropylene sutures. The latter were applied with both interrupted and continuous techniques. Intraluminal pressure was measured with a Millar Mikro-tip transducer, and vessel wall motion was determined with duplex ultrasound equipped with an echo-locked wall-tracking system. Diametrical compliance was determined. Environmental scanning electron microscopy was performed on explanted anastomoses. RESULTS: There was a reduction in anastomotic compliance and associated proximal and distal para-anastomotic hypercompliant zones with the use of all techniques. However, compliance loss was significantly less in those anastomoses with clips and interrupted sutures when compared with continuous suture (P <.001). Furthermore, the total compliance mismatch across anastomoses with continuous sutures was significantly greater than those with clips or interrupted sutures (P <.05). The mean time for constructing clipped anastomoses was 5.7 +/- 1.4 minutes, which was significantly less than either continuous (P <.0001) or interrupted sutures (P <.0001). Furthermore, environmental scanning electron microscopy demonstrated minimal intimal damage with good intimal apposition in the clip group. CONCLUSION: Anastomoses performed with nonpenetrating clips resulted in improved para-anastomotic compliance profiles and reduced intimal damage when compared with those with polypropylene sutures. These benefits may enhance long-term graft patency by reducing the risk of anastomotic intimal hyperplasia.     

Anastomotic tissue response associated with expanded polytetrafluoroethylene access grafts constructed by using nonpenetrating clips.

PURPOSE: The gross, light microscopic, and scanning microscopic appearance of arterial and venous anastomoses in expanded polytetrafluoroethylene (ePTFE) access grafts constructed with nonpenetrating clips were compared with that of those constructed with polypropylene suture. We hypothesized that clip-constructed anastomoses would provide controlled approximation of native vessel intimal and medial components with the ePTFE grafts. We further hypothesized that anastomotic healing with clips would involve primarily an intimal cellular response, as compared with suture-constructed anastomoses in which cells within the media and adventitia walls participate. METHODS: Femoral artery to femoral vein arteriovenous (AV) grafts were constructed in five dogs using 4-mm internal diameter ePTFE graft material. Each animal received one AV graft with anastomoses constructed by using polypropylene sutures in one leg and one AV graft with anastomoses constructed with Vascular Closure System clips in the contralateral leg. Animals were given aspirin for the duration of the study, and grafts were explanted at 5 weeks. At the time of explantation, graft segments were grossly evaluated and then underwent light and scanning electron microscopic analysis. RESULTS: At the time of explantation, all access grafts were patent. Joining the ePTFE grafts to the native vessels with clips resulted in minimal vessel wall damage. The lumenal contours of the discontinuous approximation were smooth and without gross endothelial disruption. These observations are in contrast to the lumenal compromise and endothelial disturbance associated with the sutured anastomoses. Furthermore, hemostasis was achieved immediately in the clipped grafts, decreasing the incidence of perianastomic hematoma. Finally, cellular reconstitution occurred at the anastomotic cleft in both the sutured and the clipped junctions. The neointima exhibited an endothelial cell lining on the lumenal surface and the presence of alpha-smooth muscle cell actin positive cells within the subendothelial layer. CONCLUSION: Vascular Closure System clips are a viable alternative to suture for the approximation of ePTFE AV access grafts to native blood vessels. The use of the clips resulted in a more streamlined anastomosis, with decreased vessel wall damage, immediate hemostasis, and a trend toward shorter procedure times.     

The natural history of intimal flaps in a canine model

The natural history of arterial intimal flaps has not been well defined. This study characterizes the natural history of unrepaired intimal flaps. Thirty-nine 1-, 2-, and 3-mm hemispheric, distally based intimal flaps were made in 4- to 5-mm diameter canine femoral and carotid arteries. Twenty arteries had 2- and 3-mm intimal flaps and were monitored for short-term arterial thrombosis and flap extension. Nineteen had 1- and 2-mm intimal flaps and were monitored for thrombosis, long-term development of neointimal hyperplasia, arterial stenosis, and persistence of the flap. While 40% of the arteries with 3-mm intimal flaps developed thrombosis in 3 to 5 days, only 3% of the arteries with 1- or 2-mm intimal flaps developed thrombosis. Most 1- to 2-mm intimal flaps resolved and the subsequent development of neointimal hyperplasia or arterial stenosis was minimal. Arteries with hemodynamically significant stenoses from intimal flaps warrant repair, while arteries with smaller intimal flaps may not require repair.     

Arterial reconstruction with vascular clips is safe and quicker than sutured repair.

BACKGROUND: Non-penetrating, arcuate-legged vascular-closure staple clips made of titanium were initially developed for microvascular anastomoses with little experience of their use in larger vessels. The purpose of this study was to compare vascular-closure staple clips to sutured anastomoses in common iliac arteries in a porcine model. METHODS: In an experimental study, transected iliac arteries on both sides of 11 pigs were randomly assigned to end-to-end anastomosis performed with vascular-closure staple clips or interrupted 6-0 polypropylene sutures. Angiographic, macroscopic and microscopic results were assessed after 2 months. RESULTS: There was no significant difference in the patency rate, tensile strength of the anastomoses, vessel diameter at the repair site, intimal thickness or wall thickness of the arteries after either method of closure. The mean (s.d.) clamp time was 19.8 (6.1) minutes for clip repair, and 36.0 (6.9) seconds for suture repair (P < 0.001). The times required for the reconstruction of the anastomoses were 17.4 (6.1) and 35.5 (7.1) minutes, respectively (P < 0.001). CONCLUSIONS: Arterial anastomoses performed with vascular-closure staple clips are faster than sutured anastomoses, and result in comparable wound healing when assessed for patency, tensile strength, degree of narrowing and intimal reaction.     

An alternative system for cerebrovascular reconstructions: non-penetrating arcuate-legged clips

Non-penetrating, arcuate-legged titanium clips (VCS) have been utilized successfully over the past five years for a variety of cerebrovascular reconstructions. These applications, including both micro and macrovascular reconstructions, their clinical outcomes and technical considerations are described. Applications include patch angioplasty of cervical carotid endarterectomies, superficial temporal to middle cerebral artery 'bypass' procedures, Takayasu's arteritis and cavernous carotid reconstructions. The non-penetrating clip has proven to be a safe and reliable alternative to suture for these demanding reconstructions. Clips provide the advantages of improved anastomotic compliance, reduced operative time, and reduced incidence of post-operative anastomotic intimal hyperplasia and stenosis. Clip related pitfalls are discussed with recommendations regarding usage.     

Laser radiation in the treatment of prosthetic graft stenosis. A preliminary study of prosthesis damage by laser energy

Transluminal laser recanalization is potentially an important new treatment of anastomotic intimal hyperplasia. However, currently used grafts or sutures may be damaged by laser radiation at power and energy levels required for plaque removal. To investigate this problem, two commonly used grafts (Dacron and polytetrafluoroethylene [PTFE]) and two types of vascular suture (polypropylene and PTFE) were exposed to argon laser radiation in vitro. Dacron and PTFE grafts recovered from amputations were also studied to determine whether graft "healing" affected graft resistance to laser damage. Power and energy levels required to perforate atherosclerotic superficial femoral arteries were determined for comparison. PTFE grafts were significantly (1.5 to 7 times) more resistant to perforation by laser energy than atherosclerotic arteries under all conditions. In contrast, Dacron grafts perforated at power and energy levels one half to one third of that required for vaporization of atherosclerotic plaque. PTFE sutures remained intact at power and energy levels above the levels that perforated atherosclerotic arteries, whereas polypropylene sutures were destroyed by very low levels of power and energy (0.5 joules at 0.5 watts). Because of the variable levels of power and energy that damage different types of prosthetic grafts and sutures, laser angioplasty should only be investigated clinically as a therapy for anastomotic intimal hyperplasia when PTFE grafts and sutures are present.     

Comparison of laser-welded and sutured arteriotomies

We compared the histologic features, tensile strength, and collagen synthesis of laser-welded and sutured arteriotomies. Four bilateral canine femoral or carotid arteries, 2 cm long, were studied at one through four weeks postoperatively, with one vessel (control) closed with interrupted 6-0 polypropylene sutures and the contralateral vessel (experimental) welded with an argon laser (0.5 W [1417 J/cm2], four-minute exposure per 1-cm length of incision). Histologic examination revealed that laser-welded arteriotomies had less inflammatory reaction, more normal collagen and elastin reorientation, and similar endothelial continuity when compared with the control, sutured wounds. The tensile strength of the one- and two-week laser-welded specimens was less than that of sutured wounds and became approximately equal to sutured repairs at three and four weeks. There were no significant differences in the rate of collagen synthesis. There was no evidence of abnormal healing in the laser-welded specimens, suggesting that argon laser welding may be an alternative to suture repair of arteriotomies.     

Impact of nonpenetrating clips on intimal hyperplasia of vascular anastomoses

Non-penetrating, arcuate-legged titanium clips create an interrupted, non-penetrated, yet compliant vascular anastomoses that is associated with significantly reduced anastomotic neointimal hyperplasia. Recent experimental and clinical studies provide evidence that the non-suture alternative changes the biology of vessel-to-vessel and graft-to-vessel connections that reduces the stimulus for hyperplasia at a number of critical points in the response to injury schema. The compliant, "blood-tight" characteristics of clipped vascular reconstructions are associated with no endothelial injury or intraluminal foreign body, minimal platelet aggregation and laminal flow. Clinical applications including vascular access, femoropopliteal bypass, and closure of carotid endarterectomies are remarkable for the absence of restenosis and preserved anastomotic patency.     

Facilitated coronary anastomosis using a nitinol U-Clip device: bovine model

OBJECTIVE: The coronary anastomosis is the most difficult part of the coronary bypass procedure, particularly when using a minimally invasive technique. Methods to facilitate coronary anastomosis will make the minimally invasive approach to coronary bypass feasible. We sought preclinical validation and testing of the design and efficacy of a self-closing penetrating clip that can be used to facilitate the creation of graft-to-coronary end-to-side anastomosis. METHODS: The nitinol U-Clip device (Coalescent Surgical, Inc, Sunnyvale, Calif) was used in 13 consecutive calves (63-118 kg). In each animal, the device was (1) used to create an anastomosis of the right internal thoracic artery to a coronary artery with the heart beating and (2) compared to polypropylene suture when used to repair two carotid arteriotomies. Intraoperative, 1-week, 8-week, and 26-week postoperative angiograms and detailed histopathologic examinations were used to evaluate anastomotic patency and healing characteristics. RESULTS: The nitinol U-Clip device successfully created right internal thoracic artery-coronary artery anastomoses and repaired carotid arteriotomy sites in 13 consecutive calves. The clip was precisely placed by means of the integrated suture and needle in a fashion similar to that used for conventional suture. The clip met design specifications by reliable release and automatic closure, thereby eliminating knot tying and assisted suture management. At the time of harvest, angiography showed widely patent coronary anastomoses (FitzGibbon grade A criteria, n = 13) and carotid arteriotomy repair sites (n = 13). Histopathologic evaluation confirmed normal healing with smooth circumferential neointimal resurfacing at the anastomotic and repair sites. CONCLUSIONS: The nitinol U-Clip design and function was validated in the formation of bovine coronary anastomoses on the beating bovine heart with excellent graft patency and healing characteristics. The nitinol U-Clip device tests favorably when compared with conventional sutures in carotid artery repair.     

Arterial repair with synthetic patch by using titanium clips

BACKGROUND: Vascular closure staple (VCS) clips made of titanium were originally developed for microvascular anastomoses. There is limited experience with their applicability to vascular reconstruction in larger vessels. This study compares VCS clips to standard sutures in arterial repair using a synthetic patch. METHODS: In an experimental study with pigs, two sequential 10-mm abdominal aortotomies were allocated randomly to synthetic patch (polytetrafluoroethylene) repair with VCS clips or continuous 6-0 polypropylene sutures. Angiographic, macroscopic, and microscopic results were assessed after 2 months. RESULTS: There were no significant differences in the patency rate, vessel diameter at the repair site, or healing indices. The mean (SD) clamp time was 8.7 (3.0) minutes for clip repair and 14.3 (7.4) minutes for suture repair (p = 0.04), and the times required for the vessel reconstruction were 5.3 (1.3) and 9.3 (3.0) minutes, respectively (p = 0.009). CONCLUSION: Patched arterial repair with VCS clips is faster than sutured reconstruction with comparable results after 2 months of follow up.     

Vascular Closure Stapler Clip Anastomosis Decreases Aortic Cross-Clamping Time Compared to Interrupted Nonabsorbable and Running Absorbable Sutures in Growing Pigs

The latest generation in titanium clip application systems, the vascular closure staples (VCS) system avoids intimal lesions and therefore minimizes the subsequent hyperplastic reaction, while at the same time enhancing distensibility and vascular growth. Moreover, VCS clips allow the surgeon to perform vascular anastomosis easily and faster than conventional suture. This system may become the option of choice for vascular reconstruction in pediatric surgery where, as in the case of aortic and transplant surgery, decreasing vascular occlusion times may influence the outcomes. The aim of this study was to determine whether VCS metallic clips would allow shorter anastomosis times than conventional interrupted polypropylene or running Dexon suturing in end-to-end anastomosis performed in the abdominal aorta of young pigs. Twenty-four domestic swine, 45 days old, were used for this study. All animals were subjected to an end-to-end anastomosis in the abdominal aorta using VCS clips, interrupted polypropylene, or running Dexon suture. Aortic cross-clamping time was significantly shorter in the VCS clips group (4.02 ± 0.72 min), compared to interrupted polypropylene (21.89 ± 1.93 min) or running Dexon (9.82 ± 3.97 min) suture. VCS clips are easy to use, and therefore may aid surgeons to significantly decrease the time needed for performing an end-to-end anastomosis in the abdominal aorta, thus decreasing cross-clamping time when compared to interrupted polypropylene or running Dexon sutures.     

Clinical experience with non-penetrating vascular clips in free-flap reconstructions.

To date, the gold standard for performing a microvascular anastomosis has been the penetrating suture with attached needle. During the last two decades, non-penetrating techniques have been introduced, including the Unilink system for end-to-end anastomoses, and the VCS clip-applier system for both end-to-end and end-to-side anastomoses. The aim of this study was to compare the results of different techniques used to create microvascular anastomoses in free-flap reconstructions. Between January 1995 and October 1999, we performed 474 microvascular anastomoses in 216 consecutive free-tissue transfers. The anastomosis techniques included manual sutures (42%), Unilink rings (34%) and VCS clips (24%). Seven combined sutured-clipped anastomoses were excluded from further analysis. The mean anastomotic time when rings were applied was significantly shorter than when using clips (P 0.0001) or sutures (P 0.0001). Venous anastomoses using clips took less time than those using sutures (P 0.05). There were 19 anastomotic failures, all of which lead to early flap failure. Ten flaps were salvaged by early reoperation; nine flaps were lost. Three more flaps were lost as a result of other causes, bringing the flap survival rate down to 94.4%. Early flap failure was caused by failure of the arterial anastomosis in eight cases; all of them were sutured (these represented 5% of all arterial anastomoses with sutures). None of the clipped arterial anastomoses failed. Early flap failure was caused by failure of the venous anastomosis in 11 patients. Three of these anastomoses were sutured (representing 6% of all venous anastomoses with sutures), seven were anastomosed with rings (representing 5% of all venous anastomoses with rings) and one was clipped (representing 2% of all venous anastomoses with clips). Both the VCS clip-applier system and the Unilink system are easy to handle and allow fast microvascular anastomoses without intraluminal penetration. The patency rate of clipped vessels is at least as good as the patency rates of vessels anastomosed using sutures or rings.     

手术缝线携载反义基因预防血管吻合口内膜增生的实验研究

目的：探讨预防血管吻合口内膜增生的新方法。了解手术缝线携载反义基因对吻合口内膜增生的影响。方法：用分别浸泡过反义，正义及错配c-myc基因溶液的保护薇乔缝线行兔颈外静脉间置于同侧颈总动脉的血管吻合。实验动物24只随机分为对照组，反义组，正义组和错配组，每组6只，4周后血管造影观察吻合口通畅情况，同时取材制片显微镜下观察其内膜增生情况，计算机图像分析测量其内膜，中膜厚度及两者比值；内膜，中膜面积及两者比值。结果：所有吻合口通畅，未见闭塞，扩张或动脉瘤，反义组的内膜厚度，内膜／中膜厚度比值及内膜面积，内膜／中膜面积比值较其他组均低（P＜0．05），其他3组间比较差异均无显著意义（P＞0．05）；各组间的中膜厚度及中膜面积间差异无显著意义（P＞0．05），结论：用浸泡过反义 c-myc溶液的保护薇乔缝线进行血管吻合，能有效地抑制血管吻合口内膜增生。     

In search of the "perfect" anastomosis

Forty-five end-to-side microvascular anastomoses were completed in rat carotid arteries of 0.7-0.8 mm diameter (anastomosing the distal end of the left common carotid to the side of the right common carotid). For comparison both 10-0 and 11-0 sutures were utilized in different anastomotic techniques: interrupted, direct-continuous, and diagonal-continuous sutures, plus total mural thickness vs. partial mural thickness (piercing only the adventitia and outer media, excluding the intima). Anastomoses were evaluated for patency and scanning electron microscopic appearance after 10 to 12 weeks. The results indicate complete patency in all anastomoses. Ultrastructural observations revealed nearly normal intimal appearance in the partial medial technique and only minimal evidence of intimal injury in the other techniques. It is concluded that 100% patency can be obtained regardless of suture size or anastomotic technique. The most important factor in anastomotic patency is the operator's technical skill.     

Nonpenetrating vascular clips for small-caliber anastomosis

In the search for better anastomosing techniques, an improved vascular stapler device (VCS clip applier system(R)) has been introduced. The system uses nonpenetrating clips to approximate everted vessel walls. The objective of this study was to determine the effects of nonpenetrating vascular clips on endothelial wound healing. Aortic end-to-end anastomoses were performed in male Wistar rats. A comparison was made between clipped (n = 12) and conventional hand-sewn (n = 6) anastomoses. Patency rates were verified at different time intervals (after 1, 4, and 8 weeks), after which the anastomotic sites were removed. Morphological evaluation was carried out using scanning electron microscopy. All rats survived the procedure. Closure with clips took less time than closure with conventional sutures, with decreasing aortic clamping times for the clipped procedures during the course of the experiments. Patency rates were 100% in both the "clipped" and "sutured" groups. Microscopic examination showed favorable endothelial healing at the clipped anastomotic sites, with less inflammatory reaction at 1 week, and a more complete endothelial regeneration at 4 and 8 weeks follow-up, as compared with the sutured anastomoses. The clip applier holds the promise of a useful device in anastomosing small-caliber vessels, since clip closure takes less time than suturing, while patency rates are identical, and morphological results are favorable. Training is mandatory to obtain technical skills and to achieve optimal results.     

Animal model to compare the effects of suture technique on cross-sectional compliance on end-to-side anastomoses.

OBJECTIVE: An animal model has been developed to compare the effects of suture technique on the luminal dimensions and compliance of end-to-side vascular anastomoses. METHODS: Carotid and internal mammalian arteries (IMAs) were exposed in three pigs (90 kg). IMAs were sectioned distally to perform end-to-side anastomoses on carotid arteries. One anastomosis was performed with 7/0 polypropylene running suture. The other was performed with the automated suture delivery device (Perclose/Abbott Labs Inc.) that makes a 7/0 polypropylene interrupted suture. Four piezoelectric crystals were sutured on toe, heel and both lateral sides of each anastomosis to measure anastomotic axes. Anastomotic cross-sectional area (CSAA) was calculated with: CSAA = pi x mM/4 where m and M are the minor and major axes of the elliptical anastomosis. Cross-sectional anastomotic compliance (CSAC) was calculated as CSAC=Delta CSAA/Delta P where Delta P is the mean pulse pressure and Delta CSAA is the mean CSAA during cardiac cycle. RESULTS: We collected a total of 1200000 pressure-length data per animal. For running suture we had a mean systolic CSAA of 26.94+/-0.4 mm(2) and a mean CSAA in diastole of 26.30+/-0.5 mm(2) (mean Delta CSAA was 0.64 mm(2)). CSAC for running suture was 4.5 x 10(-6)m(2)/kPa. For interrupted suture we had a mean CSAA in systole of 21.98+/-0.2 mm(2) and a mean CSAA in diastole of 17.38+/-0.3 mm(2) (mean Delta CSAA was 4.6+/-0.1 mm(2)). CSAC for interrupted suture was 11 x 10(-6) m(2)/kPa. CONCLUSIONS: This model, even with some limitations, can be a reliable source of information improving the outcome of vascular anastomoses. The study demonstrates that suture technique has a substantial effect on cross-sectional anastomotic compliance of end-to-side anastomoses. Interrupted suture may maximise the anastomotic lumen and provides a considerably higher CSAC than continuous suture, that reduces flow turbulence, shear stress and intimal hyperplasia. The Heartflo anastomosis device is a reliable instrument that facilitates performance of interrupted suture anastomoses.     

Vascular clips have no significant effect on the cellular proliferation, intimal changes, or peak systolic velocity at anastomoses in rabbit vein grafts

OBJECTIVE: This study compares vascular closure staples (VCSs) with conventional sutures in the rabbit carotid vein graft model to determine whether anastomotic technique affects cellular proliferation, blood velocity, or intimal changes when measured over a period of 3 months postoperatively. METHODS: Twenty-six New Zealand White rabbits weighing 3.0-3.2 kg underwent interposition of jugular vein grafts in left carotid arteries. Half of the animals had anastomoses performed with small VCSs (n = 13) and half had anastomoses performed with 8-O interrupted polypropylene suture. Animals were allowed to survive for 1 week (n = 4, VCS; n = 4, suture), 2 weeks (n = 4, VCS; n = 4, suture), and 3 months (n = 5, VCS; n = 5, suture). The peak systolic velocity (PSV) at the distal anastomosis was measured after completion of the graft and again at sacrifice in the 3-month survival groups. At sacrifice, sections were taken from the middle and distal end of the vein graft and the distal carotid artery. Vascular cell proliferation was measured using 5-bromo-2'-deoxyuridine labeling and intimal changes were measured using digitized microscopic images. RESULTS: All 26 grafts were open at the time of sacrifice. PSV at the distal clipped anastomosis was 40.52 cm/s (t = 0) and 34.3 cm/s (t = 3 months, P = 0.31). PSV at the distal sutured anastomosis was 38.30 cm/s (t = 0) and 39.23 cm/s (t = 3 months, P = 0.82). There was no difference between the two techniques at either t = 0 or t = 3 months (P = 0.51 and P = 0.31, respectively). Endothelial cell proliferation and smooth muscle cell proliferation at the anastomosis was highest during the 2 weeks after the procedure, then returned to baseline levels by 3 months. But there was no significant difference between the clipped and sutured groups with respect to vascular cell proliferation postoperatively. The intimal thickness changed significantly in the vein graft at the anastomosis for both the clipped and sutured groups (P = 0.0007 and P = 0.002). But there was no difference when the intimal changes for each technique were compared (P = 0.94). CONCLUSION: No differences were observed when peak systolic velocity, vascular cell proliferation, and intimal changes were compared between sutured and stapled anastomoses in rabbit vein interposition grafts over a period of 3 months after surgery.     

Randomized clinical trial of continuous sutures or non-penetrating clips for radiocephalic arteriovenous fistula

BACKGROUND: Despite several modifications to the original design, patency rates of radiocephalic arteriovenous fistulas have changed little since the first report in 1966. The use of non-penetrating clips for vascular anastomosis on the outcome of such fistulas was studied. METHODS: Between January 2000 and August 2003, 107 primary radiocephalic fistulas were constructed in 98 patients. The vascular anastomoses were performed at random with either sutures (n = 56) or clips (n = 51). RESULTS: Although there were trends for better primary and primary assisted patency of clipped fistulas, the differences were not statistically significant. The 6-month primary patency rate was 61 per cent with sutures and 69 per cent with clips (P = 0.393). The mean(s.d.) primary patency was 315(306) and 285(285) days for clipped and sutured fistulas respectively. With regard to secondary patency, clipped fistulas were better (P = 0.009). The mean(s.d.) secondary patency was 435(376) and 344(316) days for clipped and sutured fistulas, respectively. There were no significant differences in flow characteristics, number of revisions or other morbidity. CONCLUSION: This randomized clinical trial provided further evidence that the use of vascular clips may improve the patency rate of radiocephalic arteriovenous fistulas for haemodialysis.     

Expandable intraluminal vascular graft: a feasibility study

An expandable intraluminal graft mounted coaxially over an angioplasty balloon catheter was used in dog arteries. The graft, a wire mesh tube that has the ability to retain its expanded shape, opposes elastic recoil of the arterial wall after maximum balloon inflation. Eighteen grafts were placed in the abdominal aorta and iliac femoral, renal, superior mesenteric, and carotid arteries of eight dogs through femoral or carotid arteriotomies. Two grafts were placed in areas of artificially induced stenosis, completely restoring the lumen. Overall patency rate at 35 weeks was 77%. Histopathologic examination of patent grafts showed complete endothelialization at 3 weeks. The smaller caliber grafts and those that had outflow obstruction showed significant degrees of intimal hyperplasia.     

The effects of suturing technique and vessel size on patency after microarterial repair.

According to most of the literature, sutures for microarterial repair must include the intima to prevent an "intimal flap" and occlusion of the anastomosis. Some authors have said that vessel diameter affects patency rate. This study was designed to evaluate these two statements. The femoral arteries (about 1.0 mm in diameter), the epigastric arteries (about 0.5 mm), and the central ear arteries (about 0.5 mm) of rabbits were studied. Alternate arteries were repaired using conventional suturing techniques or sutures which included the adventitia and media but excluded the intima. The patency rate in the 1 mm or 0.5 mm vessels was not affected by inclusion or exclusion of the intima from the microarterial repair. The patency rate for conventionally repaired arteries 1 mm in diameter was significantly higher than that for 0.5 mm arteries.