Nonsuture microvascular anastomosis--experimental arterial end-to-end anastomosis using plastic adhesive and a soluble PVA tube (author's transl)

Microvascular anastomosis is now widely applied and many improved methods of the nonsuture anastomosis have been developed instead of the suture anastomosis for the purpose of saving time and making the reconstruction easier. We introduced a new nonsuture method of microvascular anastomosis using plastic adhesive and a soluble tube made of polyvinylalcohol (PVA). PVA, which had been utilized as a plasma expander, is a water-soluble polymer and its solubility is changeable depending on the degree of polimerization and percent saponification. We have made two kinds of soluble PVA tubes, the one has monolayer wall and the other double layered wall. The inner wall of the latter is more soluble than the outer wall. As plastic adhesives, we employed ethyl 2--cyanoacrylate, isopropyl 2--cyanoacrylate, and isobutyl 2--cyanoacrylate which were much superior to methyl 2--cyanoacrylate. Common carotid arteries of rats of 1.0 to 1.3 mm external diameter range were reconstructed and re-exploration was carried out at intervals of more than 7 days after operation. The anastomotic technique was very easy and it took about five minutes to reconstruct. In our last series, approximately 98 percent patency rate was achieved. The advantage of our method is that the blood stream is regained in the small soluble at the anastomotic site immediately after the release of hemostatic clamps.     

The influence of inner wall filamentousness on the performance of small- and large-caliber arterial grafts

Dacron prostheses with differing degrees of inner wall filamentousness were implanted in the canine descending thoracic aorta for 56 days (n = 14) and the carotid arteries for 21 days (n = 40). In the thoracic aorta the healed inner capsule of 8 mm internal velour grafts was approximately three times as thick as the inner capsule of external velour knitted prostheses. However, the early patency and rapidity of healing of these two types of prostheses were essentially the same. In the carotid arteries the patency of the 4 mm external velour prostheses was greater than that of the internal velour prostheses and the mean thrombus-free surface area of the external velour grafts was significantly greater than that of the internal velour grafts. These observations suggest that an internal velour surface is not deleterious to early patency in a large-caliber, high-flow artery but that it may be in a small-caliber, low-flow artery.     

Results of experimental implantation of microvascular prostheses in three recipient animal species

A total of 286 knitted vascular prostheses made of polyethylene terephthalate and surface-treated with polyurethane, polylactide, or both were implanted over the past 6 years. Of this total number, 224 prostheses were implanted in rats, nine in dogs, and 53 in pigs. We developed 39 types of knitted prostheses. The best results were obtained with prosthesis no. 36, which was surface-treated with polyurethane and polylactide. Prostheses 10 mm in length with a diameter of 2 mm implanted into rat aortas showed 100% patency during the observation periods of 2 months (ten implants) and 1 year (40 implants). Although various antithrombotic treatment schemes were tested, implantations of 5-cm- to 10-cm-long no. 36 prostheses in dogs were unsuccessful. The results of implantation of 3-mm caliber no. 36 prostheses to pigs were comparable with those obtained with Gore-Tex prostheses. Intensive antithrombotic treatment with heparin and Rheomacrodex intraoperatively followed by Fraxiparine (0.3 ml/12 h), was necessary to ensure early patency of the implants. Lower dosage of antithrombotic drugs resulted in transient incomplete occlusion of the implant. Full patency resumed after 1 month.     

Double-donor, single-lumen, end-to-side anastomosis

One of the major problems in extracranial-intracranial bypass procedure is the inadequate caliber of the superficial temporal artery branches. In this study, a new end-to-side anastomosis technique that permits two small caliber arteries to be used as a single donor vessel is presented. The external and internal branches of the right common carotid artery were modified to provide a single lumen, and an end-to-side anastomosis was performed between these vessels and the contralateral common carotid artery in 10 rats. One week after the operation, angiography was performed and the patency of anastomoses was demonstrated in 9 of 10 rats.     

Carotid artery end-to-end anastomosis in the rat using the argon laser

Microvascular end-to-end anastomoses of rat common carotid arteries measuring 0.6 to 0.7 mm in diameter were performed using an argon surgical laser system. Vascular bonding with the argon laser was accomplished in all cases. The anastomosed carotid artery segments were evaluated both angiographically and histologically at 1 day, 1 week, and 1 month after laser bonding. With increasing time after anastomosis, there was a trend toward increasing angiographically proven stenosis of the anastomotic segment and histologically demonstrated pseudoaneurysm formation of the vessel wall at the bonded site. Pseudoaneurysm formation was associated with a dense inflammatory response in the anastomotic vessel segment. In spite of excellent initial tissue bonding and vessel patency, the delayed results of progressive vessel wall disruption and segmental stenosis indicate that further experience in using the argon laser for vessel welding is needed before this method can be accepted as an alternative to current microvascular suture technique.     

Versatility of a posterior-wall-first anastomotic technique using a short-thread double-needle microsuture for atherosclerotic arterial anastomosis

To perform safe anastomosis for atherosclerotic arteries, we employed a posterior-wall-first anastomotic technique with a short-thread double-needle microsuture. Between October 2005 and September 2007, we performed 17 free flap transfers to the head and neck regions with this technique. Fifteen of 17 patients had one or more risk factors for atherosclerosis. In all patients except one, the superior thyroid artery was employed as a recipient artery and end-to-end anastomosis was performed close to its origin with the external carotid artery. Postoperatively, no anastomotic thrombosis occurred in any patients. The greatest advantage of the double-needle microsuture is that each stitch can be placed from the inner side of the arterial wall to the outer side. This "inner-to-outer" stitch secures full-thickness bite and minimizes intimal damage. Safe and reliable anastomosis could be carried out in an unfavorable setting because the double-needle suture offers a high degree of freedom in suture placement.     

Quantitative analysis of anastomotic intimal hyperplasia in paired Dacron and PTFE grafts

The purpose of this investigation was to compare and contrast the occurrence and progression of anastomotic intimal hyperplasia in two commonly used prosthetic arterial grafts. Twenty paired carotid artery interposition grafts of Dacron and PTFE (polytetrafluoroethylene) were implanted in a canine model. The grafts were electively removed at intervals from one week to seven months or at the time of thrombosis. Areas of hyperplastic growth were determined at each anastomosis using a quantitative histologic technique. The number of grafts quantitatively evaluated was 16 Dacron and 12 PTFE, excluding all thrombosed grafts. In both materials, hyperplasia occurred to a significantly greater degree at the distal or downstream anastomosis as compared with the proximal or upstream anastomosis (Dacron P less than 0.001, PTFE P less than 0.05). Quantitative and qualitative evaluation of these two commonly used but different arterial grafts did not demonstrate a significant difference in the occurrence of anastomotic hyperplasia.     

External carotid-basilar anastomosis: case report (author's transl)]

The occipital-vertebral anastomosis is one of the anastomotic channels between the external carotid system and the intracranial vessels. In this paper, we have reported a large, left external carotid-basilar anastomosis which was incidentally revealed in a patient with left hemiparesis due to arteriosclerotic occlusion of the right internal carotid artery. A 55-year-old man suddenly developed left hemiparesis without headache, unconsciousness or vomiting on the morning of January 15, 1973. When he was referred to our service on April 11, the noticeable neurological findings were left hemiparesis and left homonymous hemianopsia. The right carotid angiogram revealed occlusion of the internal carotid artery associated with collateral channels from the external carotid artery. Also a segment of the vertebral artery was visualized via the muscular branch of the occipital artery. In the left carotid angiogram, the posterior circulation was markedly visualized throught the left vertebral artery originating from the external carotid artery trunk. This anastomotic vessel had a large branch with constant caliber leading to the occipital fossa. But the posterior cerebral artery was directly visualized from the internal carotid artery without connection to the basilar artery. Repeated bilateral brachial angiograms revealed hypoplasis of the vertebral arteries. It was suggested that the persistent external carotid-basilar anastomosis might be constantly associated with hypoplasia or aplasia of the bilateral vertebral arteries.     

Bioabsorbable device for small‐caliber vessel anastomosis

Although the devices for large‐caliber vessel (>2‐mm diameter) anastomosis are available, there are no devices for performing anastomosis of small‐caliber vessels. We designed a hooked device composed of a bioabsorbable polymer for sutureless anastomosis of small‐caliber vessels. The efficacy of this device was evaluated by in vitro degradation and arterial‐fixation strength tests as well as in vivo transplantation experiments with common carotid arteries of growing SD rats. A nonabsorbable device without hooks served as the control in the fixation strength and animal experiments. The tensile strength of the bioabsorbable device decreased to 27 and 9% of the initial value after 8‐ and 24‐week incubation, respectively. The fixation strength was greater and the anastomotic time was shorter with this device than with the control. The transplantation experiments showed complete endothelial bridging in both devices at 2 weeks after surgery (n = 6). The control device created a considerable protrusion into the arterial lumen at 8 postoperative weeks, whereas the experimental device did not (n = 6). Arterial diameter measurements detected a significant difference between the inner diameters at the respective anastomotic sites (n = 6, P < 0.05) and demonstrated that the control device hindered the vessel growth while the experimental device did not. Therefore, the bioabsorbable hooked device was an effective tool for anastomosis of small‐caliber arteries (ca. 1‐mm diameter). © 2010 Wiley‐Liss, Inc. Microsurgery 30:494–501, 2010.     

Experimental laser-assisted end-to-side microvascular anastomosis

The authors present a new technique of end-to-side microvascular anastomosis in a rat carotid artery model, employing a milliwatt CO2 laser. Both carotid arteries were isolated and approximated in an end-to-side fashion by the placement of four 10-0 nylon stay sutures. The milliwatt CO2 laser was used to effect vessel anastomosis between the sutures, using 70-100 mW of power. Animals were killed 8 weeks postoperatively. Angiography of each anastomosis was performed in all animals. All anastomoses were then harvested, and submitted for histological analysis. Anastomotic patency was 100%, both intraoperatively and angiographically. There was no evidence of intravascular thrombus, anastomotic stenosis, or pseudoaneurysm formation. Early in the experiment, some anastomoses showed localized dilatation at the anastomotic site. The histologic changes at the anastomotic site are described. Laser-assisted microvascular anastomosis is a feasible technique, and a potential alternative to conventional suture techniques.     

Favorable scanning electron microscopic findings of stapled saphenous vein-carotid artery anastomoses

BACKGROUND: In the progress toward "off-pump" endoscopic coronary artery surgical procedures, new techniques for coronary artery anastomoses are being developed. One such approach is the use of nonpenetrating titanium clips. We evaluated the quality of anastomoses achieved using this technique in a porcine model of saphenous vein-carotid artery grafting using scanning electron microscopy. METHODS: Bilateral saphenous vein-carotid artery interposition grafts were implanted in 10 "white race" pigs, using the nonpenetrating clips in one side of the neck and conventional hand suturing on the opposite side. One week after operation, the grafts were harvested. RESULTS: All grafts were patent 7 days after operation, and 40 anastomoses underwent scanning electron microscopic study. In all samples, the luminal surfaces of both the carotid artery and vein graft were covered by a continuous layer of endothelial cells up to the anastomosis. Anastomotic sites in all clipped samples and most of the sutured anastomoses were completely endothelialized, and anastomotic clefts were indistinguishable. However, in 25% of sutured specimens, the suture material remained clearly visible inside the lumen of the vessel, and the subendothelial matrix remained exposed, with extensive fibrin, red blood cells, and platelet deposition on its surface. CONCLUSIONS: Because the endothelial coverage consistently appeared to be complete and the subendothelial matrix was not exposed, it is likely that the risk of early anastomotic thrombosis is reduced by using the nonpenetrating titanium clips.     

Automated distal coronary bypass with a novel magnetic coupler (MVP system)

OBJECTIVE: We sought to assess the feasibility of performing sutureless distal coronary artery bypass anastomoses with a novel magnetic coupling device. METHODS: From May 2000 to April 2001, single-vessel side-to-side coronary artery bypass grafting on a beating heart was performed in 39 domestic white pigs (35-60 kg) without the use of mechanical stabilization, shunts, or perfusion bridges. Animals were divided into 2 groups. Seventeen pigs underwent right internal thoracic artery to right coronary artery bypass grafting through a median sternotomy (group 1) with a novel magnetic vascular positioning system (MVP system; Ventrica, Inc, Fremont, Calif). Twenty-two pigs underwent left internal thoracic artery to left anterior descending artery grafting with the MVP anastomotic device through a left anterior minithoracotomy (group 2). This system consists of 2 pairs of elliptical magnetic implants and a deployment device. One pair of magnets forms the anastomotic docking port within the graft; the other pair forms an identical anastomotic docking port within the target vessel. The anastomosis is created when the 2 docking ports magnetically couple. Anastomotic patency was evaluated by means of angiography during the first postoperative week and at 1 month. Histologic studies were performed at different time points as late as 6 months. RESULTS: Right internal thoracic artery to right coronary artery anastomoses and left internal thoracic artery to left anterior descending artery anastomoses were successfully performed with the system in all animals. The self-adherent and self-aligning properties of the implants allowed for immediate and secure approximation of the arteries (total anastomotic time between 2-3 minutes). Anastomoses were constructed without a stabilization platform. Five nondevice-related deaths occurred postoperatively. One-week angiography, performed in 35 surviving animals, showed a patent graft and anastomosis in all cases. The patency rate at 1 month was 97% (33/34). Histologic studies as late as 6 months demonstrated neointimal coverage of the magnets without any significant luminal obstruction. Histology also confirmed the presence of viable tissue between magnets. CONCLUSION: The MVP anastomotic system uses magnetic force to create rapid and secure distal coronary artery anastomoses, which might facilitate minimally invasive and totally endoscopic coronary artery bypass surgery.     

"One-knot" microvascular anastomosis using glutide as an external splint--experimental arterio-arterial anastomosis in rats

Experimental microvascular anastomosis using a glutide copolymer (lactide: glycolide = 80: 20) as an external splint was undertaken in rats between the left and the right carotid arteries. Both arteries were dissected free over a 1-cm length, the left carotid artery was transected at the cranial end, and the right carotid artery was cut at the caudal end. The left carotid artery was then introduced into a glutide pipe-splint. The arterial wall was turned back 180 degrees over the edge of the splint. The reflected part of the artery and the glutide were covered with the freed-up right carotid artery. One stitch was made around the two arteries and the glutide in a manner similar to that of binding a barrel with steel wire. The "One-knot anastomosis" was then complete. We call this type of anastomosis "antegrade anastomosis". If, on the other hand, the right carotid artery is introduced into the pipe, turned back at the edge of the glutide, covered with the left carotid artery and secured with one stitch, the technique is known as "retrograde anastomosis". The patency rates of the resulting vessels were as follows: antegrade anastomosis, 83% (15/18); and retrograde anastomosis, 92% (23/25); so that the average patency rate was 88% (38/43). We measured the anastomosing time that is the time between the transection of one of the two arteries and the completion of the anastomosis. The average anastomosing time was 21 minutes for antegrade anastomosis and 14 minutes for retrograde anastomosis. But the 'pure anastomosing time' (the time taken to connect the two already prepared arteries) was 2-3 minutes. We believe that one-knot anastomosis technique for future clinical application is promising.     

Agenesis of the right internal carotid artery associated with complicated anastomosis of middle cerebral artery: a case report

A 57-year-old female was admitted to our hospital because of headache, nausea, and vomiting. Head CT scan demonstrated subarachnoid hemorrhage. Cerebral angiography showed the absence of the right internal carotid artery, and skull base CT of the bone window level revealed the absence of the right carotid canal. The right middle cerebral artery (MCA) and anterior cerebral artery (ACA) were opacified from the left internal carotid artery. The right A1 portion was hypoplastic and the distal portion of the right M1 portion was replaced by several minute complicated anastomotic vessels connected to the right M2 portion. The right MCA territory was mainly supplied by collateral flow from the right ACA and the right posterior cerebral artery via the leptomeningeal anastomosis. These was neither aneurysm nor arteriovenous malformation. The second angiography, 1 week after the initial angiography, showed the same hemodynamic pattern and aneurysms were not found. We diagnosed the patient as agenesis of the right internal carotid artery and the etiology of subarachnoid hemorrhage was suspected to be a rupture of the anastomotic vessels between the right M1 and M2. She was discharged on the 21st hospital day without any neurological deficit.     

In vitro laser recanalization of chronically occluded prosthetic grafts.

Polytetrafluoroethylene (PTFE) and Dacron grafts were implanted in canine femoral and carotid arteries using PTFE and Prolene suture, respectively. Arteries containing occluded grafts were explanted and laser recanalization was attempted in vitro. Laser recanalization was successful in 78% of PTFE grafts compared to 30% of Dacron grafts. Recanalization was complete (residual stenosis less than 5%) in opened PTFE grafts, whereas residual stenosis averaged 60% in recanalized Dacron grafts. PTFE graft/PTFE suture anastomotic tensile strength was unchanged after recanalization, while Dacron graft/Prolene suture anastomotic tensile strength decreased significantly. In addition, anastomotic bursting pressure was significantly higher for lased PTFE grafts with PTFE sutures (300 mg Hg) compared to lased Dacron grafts with Prolene sutures (70 mm Hg). Chronically occluded PTFE grafts with PTFE suture can be safely and effectively opened by laser recanalization. In contrast, attempted laser recanalization of Dacron grafts sutured with Prolene suture is seldom successful, significantly weakens the graft artery anastomosis, and should be avoided.     

Basic fibroblast growth factor released from a platinum coil with a polyvinyl alcohol core enhances cellular proliferation and vascular wall thickness: an in vitro and in vivo study

OBJECTIVE: We developed a new type of platinum coil that has a polyvinyl alcohol (PVA) core to absorb and release various biologically active materials for the endovascular treatment of intracranial aneurysms. We evaluated its efficacy as an embolic material with basic fibroblast growth factor (bFGF) in an in vitro and in vivo study. METHODS: A small PVA thread was inserted into the central space of the primary coil. This coil was named the PVA-core coil. Ten-millimeter segments of the PVA-core coil were used in this study. PVA-core coils were immersed in a bFGF solution for 1 hour. The PVA-core coil, which absorbed bFGF in the PVA-core, was named the FGF-core coil. Initially, the dose of bFGF released from the PVA core into saline was measured by performing an enzyme-linked immunosorbent assay. In the in vitro study, FGF-core coils, PVA-core coils, and unmodified coils were cultured with fibroblasts (NIH3T3), and then their surfaces were observed with electron microscopy. In the in vivo study, each coil was implanted into a rat common carotid artery. The rats were killed, and the arterial lumen was histologically examined at 14 and 28 days after coil implantation. RESULTS: BFGF was released from the PVA core into saline within 24 hours by performing an enzyme-linked immunosorbent assay. Electron microscopic findings demonstrated remarkable cellular adhesion to the surfaces of the FGF-core coils, but no adhesion to the surfaces of the PVA-core coils and the unmodified coils was found. Histologically, remarkable cell proliferation in the vascular lumen was demonstrated in the common carotid arteries of the FGF-core coil implantation group at the 14th and 28th days. Cellular components proliferated around the implanted coil, and these components mainly stained blue with Masson trichrome. These changes did not occur in the PVA-core coil group and the unmodified coil group. CONCLUSION: We suggest that FGF-core coils may be effective in inducing fibrotic changes inside aneurysms. These coils may be used as an embolic material to cure cerebral aneurysms.     

Arterial anastomosis using the telescoping method and an elastomeric adhesive

We experimentally studied a new technique for anastomosis of small arteries which involves the telescoping method and a surgical adhesive with the objective of examining its clinical potential. This technique was applied to the unilateral femoral arteries of 27 mongrel dogs. After division of the artery, the distal artery was incised longitudinally, and the proximal end was invaginated into the opened artery. One stay suture and the elastomeric adhesive PUP201 were placed in the anastomotic site. The bursting and tensile strength and the patency were examined, and a histopathological study was performed at various intervals up to 1 year after the operation. The bursting strength exceeded 500 mm Hg. The patency rate of the anastomosed arteries was 100%. The mean percentage of stenosis to diameter of the proximal normal lumen was 20% one year after operation. The luminal surface of the anastomosed line was healed smoothly, and thrombi between the telescoped arteries were replaced by elastofibrotic union. In conclusion, small arterial anastomosis using the telescoping method and an elastomeric adhesive is easy and safe and provides good patency.     

Experimental microvenous reconstructions with Gore-Tex polytetrafluoroethylene prosthesis implanted by means of the sleeve anastomotic technique

Polytetrafluoroethylene (PTFE) prostheses (Gore-Tex; ID, 1 mm; length, 5-7 mm; wall thickness, 0.2 mm; fibril length, 30 microns, n = 28) were implanted into the rat femoral vein by means of the sleeve anastomotic technique to enhance the patency rate. In the control group, PTFE prostheses (n = 8) were implanted by means of the end-to-end technique. In the experimental group patency and healing of the PTFE prostheses were evaluated at 1 day (n = 4), 1 week (n = 6), 3 weeks (n = 6), 6 weeks (n = 6), and 12 weeks (n = 6) after implantation by means of macroscopic inspection and routine light and scanning electron microscopy. All prostheses, except one at 1 week after implantation, were patent at the time of removal. All of the microvenous prostheses were completely covered by an endothelial layer at 3, 6, and 12 weeks after implantation. Occasionally some smooth muscle-like cells could be found underneath this endothelial layer, but stenosis was never observed at the anastomotic sites. Only scarce tissue ingrowth was observed in the wall of the PTFE prostheses. In the control group, all prostheses, except one prosthesis after 3 weeks, were found to be occluded. An occlusive mural thrombus was found firmly attached at the anastomoses at 1 day, and an organized thrombus at 3 weeks after implantation. The patent prosthesis demonstrated complete endothelial healing. These results demonstrate the importance of the sleeve anastomotic technique and the potential of PTFE prostheses as a microvenous conduit when implanted by means of the sleeve anastomotic technique in experimental reconstructive microvascular procedures.     

Plasma polymerized tetrafluoroethylene/polyethylene terephthalate vascular prostheses

Tetrafluoroethylene (TFE) was discharged onto woven polyethylene terephthalate (PET) prostheses, and the PET prostheses (50 mm long) with or without TFE were implanted into canine carotid arteries and aortas. Additional controls included polytetrafluoroethylene and Dacron. Specimens were explanted after one to 12 months, photographed, and sectioned for light and scanning and transmission electron microscopy, and thrombus-free surface areas calculated by computerized planimetry. Results showed no significant patency differences among carotid or aortic groups. However, both PET carotid groups had significantly greater thrombus-free surface areas. Histologically, both PET groups appeared identical. An endothelialized neointima covered PET carotid specimens by six months, compared with three months in the aortic position, with greater pannus ingrowth in both PET groups. Plasma polymerized TFE offered no additional advantage in these long-term experiments.     

大鼠颈总动脉端端吻合术后的血流动力学动态观察

研究小动脉端端吻合术后血流动力学变化，为进一步的研究提供依据。选用ＳＤ大鼠１０只，切断左侧颈总动脉行端端吻合。术后６，１２，２４，４８，７２和１２０小时，用彩色多普勒血流仪经皮连续测定实验侧颈总动脉吻合口近端、吻合口、吻合口远端，以及对照侧颈总动脉的收缩期最高血流速度，计算吻合口横切面的狭窄面积百分比。结果显示，术后各个时间段，吻合口收缩期最高血流速度均明显高于吻合口近端、吻合口和对照侧颈总动脉的血流速度（Ｐ＜０．０５）；吻合口远端的收缩期血流速度均低于吻合口近端和对照侧颈总动脉的血流速度（Ｐ＜０．０５），血流速度分别降低３３．１８％和３３．３３％。术后６小时～１２０小时均出现不同程度的狭窄，平均减少４２．４８％。认为，小动脉端端吻合术后６小时～１２０小时，吻合口血流速度均明显高于吻合口近端和吻合口远端的血流速度；吻合口远端的流速均明显低于吻合口近端的流速；吻合口及其近、远端的血流速度变化不一致。