Review of facilitated approaches to vascular anastomosis surgery

Compression of the vascular wall to create a friction fit in a vascular anastomotic coupler

A previously reported microvascular coupler was shown to effectively create vascular anastomoses, but was too large for practical clinical use. To safely reduce coupler size, certain failure modes needed to be better understood. The coupler functions, in part, by compressing the vessel wall between two concentric rings, creating a friction fit that anchors the device to the vessel. This work investigates the relationship between vessel wall compression and resulting friction fit strength to ensure reducing coupler size will not unduly increase the risk that this friction fit might fail. Vascular walls were compressed to a specified strain and the tensile force required to overcome the resulting friction was measured. Experiments were conducted with various vessel types (Porcine common carotid artery, splenic artery, and jugular vein), across a range of compressive strains (55-95%), and by using either PEEK or HDPE to compress the vessel. Tensile force was increased at a rate of 5 g/min or held constant for 24 h. For experiments with incrementally increasing force, the force at failure varied with compressive strain via a power function. At 70% compression, PEEK produced 4.6 times stronger friction fits than HDPE, and common carotid arteries and splenic arteries produced 1.8 and 1.3 times stronger fits than jugular veins respectively. For experiments where tensile force was applied for 24 h, much lower forces were required to overcome friction. These results were compared to friction fit failure in a coupler prototype and it was found that the prototypes failed at just 30% of the force required to cause vessel slip under the other test conditions. These results were used to develop a model that predicts the probability of device failure via vessel slipping (one design, smaller than previously reported, was estimated to fail at maximum in vivo axial stress once in 500 anastomoses, a potentially safe level of risk).

3D-Printed Sugar-Based Stents Facilitating Vascular Anastomosis

Microvascular anastomosis is a common part of many reconstructive and transplant surgical procedures. While venous anastomosis can be achieved using microvascular anastomotic coupling devices, surgical suturing is the main method for arterial anastomosis. Suture-based microanastomosis is time-consuming and challenging. Here, dissolvable sugar-based stents are fabricated as an assistive tool for facilitating surgical anastomosis. The nonbrittle sugar-based stent holds the vessels together during the procedure and are dissolved upon the restoration of the blood flow. The incorporation of sodium citrate minimizes the chance of thrombosis. The dissolution rate and the mechanical properties of the sugar-based stent can be tailored between 4 and 8 min. To enable the fabrication of stents with desirable geometries and dimensions, 3D printing is utilized to fabricate the stents. The effectiveness of the printed sugar-based stent is assessed ex vivo. The fabrication procedure is fast and can be performed in the operating room.

Thermal denaturation behavior of collagen fibrils in wet and dry environment

We have developed a new minimally invasive technique--integrated low-level energy adhesion technique (ILEAT)--which uses heat, pressure, and low-frequency vibrations for binding living tissues. Because the adhesion mechanism of the living tissues is not fully understood, we investigated the effect of thermal energy on the collagen structure in living tissues using ILEAT. To study the effect of thermal energy and heating time on the structure of the collagen fibril, samples were divided in two categories-wet and dry. Further, atomic force microscopy was used to analyze the collagen fibril structure before and after heating. Results showed that collagen fibrils in water denatured after 1 minute at temperatures higher than 80 °C, while partial denaturation was observed at temperatures of 80 °C and a heating time of 1 min. Furthermore, complete denaturation was achieved after 90 min, suggesting that the denaturation rate is temperature and time dependent. Moreover, the collagen fibrils in dry condition maintained their native structure even after being heated to 120 °C for 90 min in the absence of water, which specifically suppressed denaturation. However, partial denaturation of collagen fibrils could not be prevented, because this determines the adhesion between the collagen molecules, and stabilizes tissue bonding.

Magnetic ring anastomosis of suprahepatic vena cava: novel technique for liver transplantation in rat

To improve the technique of suprahepatic vena cava (SHVC) reconstruction in rat OLT, novel magnetic rings were designed and manufactured to facilitate reconstruction of SHVC and shorten the anhepatic time. One-hundred and twenty adult male Wistar rats were randomly divided into two groups: rings group (n = 30), using magnetic rings for SHVC reconstruction; suture group (n = 30), 7/0 prolene suture was used for SHVC running anastomosis as control. Cuff techniques were used for portal vein and infrahepatic vena cava reconstruction as Kamada and Calne described. The bile duct was reconnected with a stent. The hepatic re-arterialization was omitted. In the rings group, the SHVC reconstruction took 0.91 ± 0.24 (mean ± SD) min; the anhepatic phase and the recipient operation time were 5.63 ± 0.65 min and 36.02 ± 8.02 min, respectively. In suture group, the anastomotic time of SHVC was 10.40 ± 2.11 min; the anhepatic phase and the recipient operation time were 17.76 ± 2.51 and 49.38 ± 12.06 min, respectively, and there was statistically significant difference between the two groups. The ALT levels reached peak at 24 h post-OLT (186.2 ± 32.5 IU/l) and restored to normal level at 96 h gradually. In the rings group, 29 of 30 rats survived at day 7 and 28 of 30 rats survived at day 30. In contrast, only 25 of 30 recipients in suture group remained alive at day 7 and 22 of 30 remained alive at day 30 (P < 0.05). Better anastomotic healing was founded in rings group by pathology and scanning electron microscope. The magnetic rings technique provides a novel, simple method for SHVC reconstruction of OLT in rat. It significantly shortens anhepatic phase, while the success rate of the operation is satisfactory.

Preparation of well-defined poly(ether-ester) macromers: photogelation and biodegradability

Two series of poly(ether-ester)-based bis-functional macromers terminated with acrylate groups and a well-defined number of ester bonds were synthesized. One series had a chain of 1, 3 or 5 ester bonds at both ends of the central poly(ethylene glycol) block (molecular weight, about 1000), while the other had an alternating structure of oligo(ethylene glycol) each of them linked to two ester bonds, in which 6 or 10 ester bonds were incorporated equally in the macromer molecules and the total molecular weight was adjusted by about 1000. Irradiation of all poly(ether-ester) macromers mixed with camphorquinone resulted in the formation of gels. Gel yield increased and hydrophilic properties of the gels produced decreased with irradiation time. The elastic modulus of the gels decreased with the number of ester bonds. Upon incubation in a PBS solution (pH 8.04), all gels were gradually degraded with time. At 3 weeks of incubation, the degradation ratio increased linearly with the number of ester bonds per unit of molecular weight of the macromers. The order of in vivo degradation rates determined from weight loss was similar to that of the in vitro study. Thus, these poly(ether-ester) macromers may be useful for biodegradable biomaterials or tissue engineering scaffolds.

Demonstration of the histopathological and immunohistochemical effects of a novel hemostatic agent, Ankaferd Blood Stopper, on vascular tissue in a rat aortic bleeding model

Background

Ankaferd Blood Stopper^® (ABS) is a folkloric medicinal plant extract used as a hemostatic agent in traditional Turkish medicine. This experimental study investigated the histopathological and immunohistochemical effects of ABS on vascular tissue in a rat model of aortic bleeding.

Methods

Four groups of 11 Wistar albino rats were used. The abdominal aortas of the rats were wounded; an ABS-soaked tampon was applied to rats in Groups 1 and 3, and a plain gauze tampon was applied to rats in Groups 2 and 4 until the bleeding stopped. The bleeding time was recorded. Immediately following sacrificing, the arteriotomy sites from Groups 1 and 2 were removed. The abdominal incisions in Groups 3 and 4 were closed following hemostasis. On Day 7 of the study, Group 3 and 4 rats were sacrificed and the abdominal aorta arteriotomy sites were removed for histopathological and immunohistochemical evaluation.

Results

The mean bleeding time in 15 animals in Groups 2 and 4 was 4.9 ± 0.6 s, and in 22 animals in Groups 1 and 3 was 3.1 ± 0.6 s. Distal aortic occlusion was not observed on either Day 1 or 7 in any group. Significantly more widespread and dense endothelial nitric oxide synthase (eNOS) staining was observed in Group 1 animals than Group 2. On Days 1 and 7 after application of ABS, histopathological changes, consisting of necrosis, inflammation, and endothelial cell loss, in the rat abdominal aortas did not differ between Groups 1 and 2. The basophilic discoloration in the ABS group on the operation day was a result of a foreign body reaction and hemosiderin-loaded histiocyte accumulation, which occurred on Day 7.

Conclusions

In this study, hemostasis was successfully achieved with ABS in rat abdominal aortas. No histopathological change was found in the rat abdominal aortas between the ABS and control groups on Days 1 and 7. Further studies on the long-term effects of foreign body reactions and hemosiderin-loaded histiocyte accumulation are required.

Suture-free technique of extravesical ureteroneocystostomy with ring pin stapler: experimental study of canines. I. Preliminary results

OBJECTIVES

To compare the mechanical and sutured ureteroneocystostomy in a canine model.

METHODS

In 18 dogs, extravesical ureteroneocystostomy on 1 side was randomly assigned to end-to-side anastomosis performed with a titanium ring-pin stapler or interrupted absorbable sutures. To create the antireflux tunnel, the longitudinal line of the muscle layer was closed over the implanted ureter with titanium clips or sutures. At 3 months postoperatively, renal ultrasonography, intravenous urography, ascending cystography, the Whitaker test, and the macroscopic and microscopic results were assessed.

RESULTS

The ureteroneocystostomy with the ring pin stapler and the antireflux tunnel construction with titanium clips had a 100% technical success rate. Compared with manual suturing anastomosis, the suture-free technique took a significantly shorter time and resulted in slightly, but not significantly, less ureteral obstruction after 3 months. One dog in group 2 had evidence of ureteral dilation and hydronephrosis compared with the normal contralateral side. No signs of stone formation, urinary cyst, or fistulas were found after either closure method. None of the 18 dogs demonstrated vesicoureteral reflux. Histologic examination showed no signs of acute inflammation or marked fibrosis in any of the 18 specimens. Moreover, the intrapelvic pressure in group 1 was approximately similar to that of the normal contralateral side.

CONCLUSIONS

Ureteroneocystostomy performed with a titanium ring-pin stapler is feasible and faster than using conventional sutures. This suture-free technique is simple and safe, with possibly lower complication rates than a nonstented suture technique. Additional studies with a longer follow-up duration are needed to confirm these results.

Laser-assisted end-to-end BioWeld anastomosis in an ovine model

The BioWeld tube, an albumin-based exovascular stent, has been used for microsurgical anastomoses and compared to conventional sutures. The study presented investigated the potential of the BioWeld tube for vascular anastomosis in larger vessels. Laser-assisted BioWeld anastomoses were compared to conventional-sutured anatomoses of the carotid artery of Merino-x ewes. The BioWeld procedure resulted in 100% survival and 100% patency at 1 and 6 week post-operative periods, with no noticeable foreign body response. Sutured animals showed 100% survival and patency. The ischemic time for BioWeld anastomosis averaged 15 minutes compared with 10 minutes for sutures. This study indicates that the BioWeld tube is an easy to use anastomotic technique with equivalent success rates and comparable anastomotic times.

Vein graft anastomoses with magnets

BACKGROUND

Performing vascular anastomoses requires complete circumferential access and is time-consuming and technically challenging. The purpose of our study was to assess a sutureless magnetic device for anastomosing vein grafts.

METHODS AND RESULTS

Oval magnets with a lumen were placed in six male foxhounds. The femoral artery was ligated and an 8 cm length of femoral vein was harvested and reversed. After a 4 mm venotomy or arteriotomy, one magnet was inserted into each vessel lumen and a second magnet was placed outside the vessel but aligned directly over the intraluminal magnet, forming a magnetic port in each vessel. The graft and target vessels were then allowed to self-align and seal, creating a side-to-side anastomosis. Patency was confirmed with duplex Doppler ultrasound scans after 6 and 13 weeks and during explantation after 14 weeks. At that time, the contralateral femoral vein was harvested and an acute graft was created as a control. Macroscopically there was no sign of stenoses or aneurysms. After explant, saline was perfused through all grafts and the hydrodynamic resistance was quantified. There was no significant difference in resistance between the acute and 14-week grafts indicating stenosis. Microscopic examination of 14-week anastomoses showed that all blood-contacting surfaces were well-endothelialised.

CONCLUSIONS

The magnetic vascular coupler allowed sutureless anastomoses between blood arteries and veins. This device might prove useful for anastomosis of large and small vessels, as well as for anastomosis or approximation of non-vascular structures such as peripheral nerves, fallopian tubes or ureters.

Sutureless Vascular Anastomoses by N-Butyl-2 Cyanoacrylate Adhesive: An Experimental Animal Study

BACKGROUND

The purpose of this animal study was to find out whether sutureless anastomoses using N-butyl-2-cyanoacrylate were effective in the suppression of neointimal hyperplasia or not.

MATERIAL AND METHODS

Ten male adult mongrel dogs were used in this animal study. The animals were randomly divided into a control group (n = 5) and a study group (n = 5). The study group underwent sutureless anastomoses using N-buthyl-2-cyanoacrylate adhesive. Infrarenal aortoaortic graft was interposed using polytetrafluoroethylene.

RESULTS

In the study group, the mean intimal thickness at the proximal anastomosis was 27.4 +/- 1.94 microm and 27.4 +/- 1.51 microm at the distal anastomosis. In the control group, the mean intimal thickness was 138.4 +/- 5.02 mum at the proximal anastomosis and 67.6 +/- 6.42 microm at the distal anastomosis. Intimal thickness at the proximal and distal anastomoses in the control group was significantly (p < 0.001) greater than in the study group. Also, perianastomotic inflammation was more obvious in the control group compared to the study group (p < 0.01).

CONCLUSION

Sutureless anastomoses using with N-butyl-2-cyanoacrylate adhesive might be a good alternative to conventional suture technique.

Development of biotube vascular grafts incorporating cuffs for easy implantation

We are developing functional autologous tubular tissues, called biotubes, as ideal small-caliber vascular grafts that have growth potential without immunological rejection. In this study, to improve surgical handling, a novel biotube reinforced at the anastomosis regions was designed. Silicone rods, 2 mm in diameter and used as a mold, were covered with two pieces of short polyurethane sponge tubing as anastomotic reinforcement cuffs at both ends. After the assembly was placed into dorsal subcutaneous pouches in rabbits for 1 month, seamless biotubes incorporating the cuffs were obtained. The interstices and surfaces of the cuffs were impregnated and covered with connective tissues similar to those of the biotubes, mainly consisting of collagen and fibroblasts. Since the tubular shape of both ends was rigidly maintained, end-to-end anastomosis by conventional microsurgery techniques between biotubes and native carotid arteries was very easy. In preliminary autoimplantation studies, angiographic observation of up to 2 months duration showed no formation of aneurysms or rupturing.

In vitro toxicity test of ethyl 2-cyanoacrylate, a tissue adhesive used in cardiovascular surgery, by fibroblast cell culture method

BACKGROUND

The aim of this study was to evaluate the cytotoxicity of cyanoacrylate polymers (ethyl 2-cyanoacrylate) by an elution test system. In such systems, the material is extracted with a cell culture medium, which is subsequently added onto cultured cells, resulting in an indirect contact between the biomaterial and cells.

METHODS

A cell line commonly utilized for cytotoxicity experiments; L929 mouse fibroblasts were used in this study. The effects of extract dilutions on cells were evaluated by two experiments: (a) The cells were suspended and seeded in a medium containing the extract, followed by a short incubation to observe the effects on cell attachment; (b) cells were seeded in a normal medium. Following cell attachment, this was replaced with a medium containing the extract and long-term effects on cell proliferation were measured. The cytotoxicity was quantified using a cell viability assay, well established for use in the evaluation of cell-biomaterial interactions.

RESULTS

These results indicate that, in the test system utilized, a tenfold dilution of the extract results in an approximately 10% decrease in cells; this increases to between 30% and 45% in a 1:1 dilution. When a large number of cells (3000/well) were used, proliferation of cells overcame the cytotoxic effect and consistent results could not be observed.

CONCLUSIONS

In this study, the observed outcomes follow a similar trend on cell attachment and proliferation with acute effects (4 hours incubation) of the extracts on the cells, producing slightly higher toxicity. Our findings are parallel with the literature findings.

Long-term effects in distal coronary anastomoses using different adhesives in a porcine off-pump model

OBJECTIVE

Adhesives are useful supplements to seal distal coronary anastomoses, particularly in patients who receive less-invasive coupling techniques. Information regarding long-term structural effects after application, however, is limited. The purpose of this large animal study was to examine the effects of 3 different commercially available surgical adhesives.

METHODS

Twelve end-to-side anastomoses were created between the left internal thoracic artery and the left anterior descending coronary artery in a porcine beating heart model. Three different adhesives were applied externally and circumferentially to the anastomosis site. In group I (n = 4) gelatin-resorcinol-formaldehyde glue (Cardial, Technopole, Sainte-Etienne, France), in group II (n = 4) n-butyl-2-cyanoacrylate glue, and in group III (n = 4) albumin-glutaraldehyde glue were used. All anastomoses were examined intraoperatively by flow measurement. After 3 months the anastomoses were reassessed for patency and the vessels were evaluated histologically.

RESULTS

By means of 4 stay sutures and subsequent glue application, anastomoses could be created successfully on the first attempt in all animals. Perioperative flow through the left internal thoracic artery was similar in all groups. In 4 animals an additional suture was placed to control bleeding. After 3 months, the patency rate was 83.3% (10/12). In group I all anastomoses were patent whereas in both groups II and III one anastomosis was occluded. None of the adhesives caused impaired vessel wall healing but they did demonstrate moderate-to-dense adhesions to the surrounding tissue. On histologic examination, gelantin-resorcinol-formaldehyde glue exhibited minimal tissue reaction (foreign-body granuloma) whereas n-butyl-2-cyanoacrylate glue showed moderate reaction. In contrast, albumin-glutaraldehyde glue caused severe inflammatory reaction with extensive fibroblastic proliferation.

CONCLUSION

Construction of an end-to-side internal thoracic artery-coronary artery sleeve anastomosis using adhesives was feasible in the pig. Among the tissue adhesives used in this study, gelantin-resorcinol-formaldehyde glue appeared to be superior to cyanoacrylate and albumin-glutaraldehyde glue. The latter one, however, caused severe adverse histologic effects and thus cannot be recommended for bonding coronary anastomoses.

Clinical experience with the Heartflotrade mark System in coronary surgery

In coronary artery bypass grafting (CABG), distal graft to coronary anastomoses are currently performed with running sutures or, to a limited extent, interrupted techniques, which are more time-consuming. The Heartflotrade mark anastomotic device, introduced in 2000, automates the suturing process via simultaneous delivery of ten standard polypropylene sutures through the graft and the coronary vessel wall to construct the anastomosis. Clinical testing was performed after extensive animal studies in several centers in Europe and Canada. After the foot shape of the device had been changed in conjunction with a reduction of its diameter, coronary arteries of 1.5 mm were successfully grafted. During the clinical studies and early follow-up, no device related injuries were reported. However, as suture management was still time-consuming with the newest versions of the device, development of automated knot tying systems or - at least - a facilitated suture management is mandatory as the next development step.

Arterial Anastomosis Without Sutures Using Ring Pin Stapler for Clinical Renal Transplantation: Comparison With Suture Anastomosis

PURPOSE

The metal ring pin stapler was initially developed for microvascular surgery and there has been little experience of their use in larger vessels. We determined if the titanium ring pin coupling system could be safely and rapidly applied for arterial reconstruction in clinical renal transplantation.

MATERIALS AND METHODS

The donor renal artery was end-to-end anastomosed to the internal iliac artery with titanium ring pin staplers in 36 patients. Anastomotic, clamp and total operative time and vascular problems were compared with those in the control group of sutured anastomosis in 39 transplant recipients.

RESULTS

The completion of mechanical anastomosis required half the time of suture anastomosis. Mean clamp time was 17.8 minutes in the nonsuture group and 28.1 minutes in the control group. There was no significant difference in total operative time between the 2 groups. A small anastomotic line leak was noted in each group, which was temporary and self-limited. There were no postoperative anastomotic failures, postoperative bleeding episodes or need to revise the anastomosis (100% patency rate) in the 2 groups. Of the patients 61 were followed for 2 to 5 years. Transplant renal artery stenosis was observed in 1 patient in the nonsuture group but 3 in the control group.

CONCLUSIONS

The anastomotic technique with the ring pin system is safe and simple, permitting an expeditious and everting anastomosis with a smooth intima-to-intima junction. Application of this technique may decrease warm ischemia time and the incidence of anastomotic artery stenosis, thus, improving outcomes.

Development of sutureless vascular connecting system for easy implantation of small-caliber artificial grafts

A novel sutureless vascular connecting system, an assembly with a delivery rod, an introducing sheath, and a connecting device, was developed for easy implantation of small-caliber vascular grafts less than 2 mm in internal diameter. A microporous stainless tube (length 2 mm, external diameter 1.6 mm, wall thickness 65 microm, pore diameter 400 microm, pore-to-pore distance 500 microm) was designed to serve as a connecting device. The feasibility of the system was tested using two types of preliminary animal experiments. One animal model consisted of graft implantation into the rat abdominal aorta (1.5 mm in diameter). The connecting device was inserted into the proximal and distal ends of the aorta through the introducing sheath by pushing the delivery rod with the connecting device placed over it. Subsequently, the aortic segments were inserted into both ends of model grafts made of segmented polyurethane (1.8 mm in internal diameter) and were fixed with banding silk threads from the exterior. The procedure was completed within 20 min without requiring specialized microsurgery techniques. Blood leakage and obstruction did not occur. The second model consisted of an end-to-end anastomosis between rabbit common carotid arteries (2 mm in diameter), which was performed within several minutes of blood flow interruption. Scanning electron microscopy demonstrated that the luminal surface of the device was fully covered with endothelial cells (ECs) after 1 week as a result of transluminal ingrowth of native ECs through the micropores in the device. This endothelialization may prevent early thrombus-induced occlusion. This simple and "easy-to-learn" technique will promote the development of small-caliber arterial grafts, and furthermore, it may have potential for clinical application.

Side-to-side sutureless vascular anastomosis with magnets

OBJECTIVE

Abbe and Payr introduced vascular techniques and devices to facilitate vessel anastomosis over a century ago. Obora published the idea of a sutureless vascular anastomosis with use of magnetic rings in 1978. The purpose of this study was to assess the performance of a new magnetic device to perform a side-to-side arteriovenous anastomosis in a dog model.

MATERIAL AND METHODS

Male fox hounds (25 kg) were treated preoperatively and daily postoperatively with clopidogrel bisulfate (Plavix) and aspirin. The femoral artery and vein were exposed unilaterally in 3 dogs and bilaterally in 4 dogs (n = 11 anastomoses). A 4-mm arteriotomy was performed, and 1 oval magnet 0.5 mm thick was inserted into the lumen of the artery and a second magnet was applied external to the artery, compressing and stabilizing the arterial wall to create a magnetic port. An identical venous magnetic port was created with another pair of oval magnets. When the 2 ports were allowed to approach each other, they self-aligned and magnetically coupled to complete the arteriovenous anastomosis. Patency was assessed for the first hour with direct observation, again after 9 weeks with duplex ultrasound scanning, and at 10 weeks under direct open observation. The anastomoses were explanted after 10 weeks. Hydrodynamic resistance was measured ex vivo on the final 8 anastomoses by measuring the pressure drop across an anastomosis with a known flow rate.

RESULTS

After implantation, very high flow created visible turbulence and palpable vibration. All 11 anastomoses were patent under direct observation and palpation. Ten of 11 anastomoses were clearly patent on duplex scans, and patency of 1 anastomosis was questionable. Hydrodynamic resistance averaged 0.73 +/- 0.33 mm Hg min/mL (mean +/- SEM).

CONCLUSIONS

Vascular anastomoses performed with magnets demonstrated feasibility; exhibited 100% patency after 10 weeks in a dog arteriovenous shunt model; lacked apparent aneurysm or other potentially catastrophic failure; demonstrated remodeling of the vessel wall after several weeks to incorporate the magnets, making the magnetic force unnecessary; and warrants further study in vessels with different sizes, flow rates, and locations.

CLINICAL RELEVANCE

We present a magnet-based device used to perform side-to-side peripheral vascular anastomoses. Its advantages include the ability to anastomose vessels without requiring circumferential surgical exposure. Vascular anastomosis performed with these magnets demonstrated 100% patency in the dog, lacked apparent aneurysm or other potentially catastrophic failure, and demonstrated remodeling of the vessel wall after several weeks, to incorporate the magnets, making indefinite retention of field strength unnecessary. This technique could enable minimally invasive procedures, such as complex reconstructive and revascularizing surgery, and warrants further study in vessels with different sizes, flow rates, and locations.

Absorption of ethyl 2-cyanoacrylate tissue adhesive

The aim of this study was to investigate absorption of ethyl 2-cyanoacrylate glue when used as a tissue adhesive. Ethyl 2-cyanoacrylate was applied subcutaneously to four rats; its presence in blood and urine was investigated by using High Pressure Liquid Chromatography. Blood samples were drawn at baseline and after 2, 4, 6, 24, 48, 54, 78, 96 hours following application. Urine samples were obtained at baseline and after 4, 24, 48, 72, 96 hours. Administration of ethyl 2-cyanoacrylate resulted in its absorption of unchanged ethyl 2-cyanoacrylate and unknown metabolites, in plasma and urine.

Bipolar Anastomosis Technique with Removable Instruments: An Easy, Fast, and Reliable Technique for Vascular Anastomosis

The interrupted suture technique is most commonly used for microsurgical vascular anastomosis. For several reasons (e.g., exposure of suture material to blood, time needed), many attempts have been made to find other solutions. This article describes a new means of performing a microsurgical vascular anastomosis. The aim of this study was to show the feasibility and possible advantages of this new technique. The basic components at work here are a modified cuff and electrically generated heat used to unite the vessel walls. In this way, both endothelial layers are adapted without manipulating the inside of the vessel or leaving behind foreign matter. Various energy/coagulation time settings were used to perform arterial anastomoses (n = 42) in an isogeneic abdominal aorta interposition model in the rat. The quality of anastomosis was evaluated at days 1, 10, 21, and 120. Immediately after the welding process all anastomoses (n = 42) were patent. No stenosis was found at any observation time. Anastomosis time ranged from 3 to 18 minutes (average, 11 minutes). This new technique permits a vascular anastomosis to be performed easily and reliably with a high patency rate. With this technique, the authors are convinced that a skilled surgeon can create a high-quality anastomosis in a fraction of the time needed to sew an anastomosis.

Initial experience with sutureless proximal anastomoses performed with a mechanical connector leading to clampless off-pump coronary artery bypass surgery

BACKGROUND

We report our early experience with the Symmetry Aortic Connector (St. Jude Medical, St. Paul, MN) used for sutureless proximal aortosaphenous vein graft anastomoses without any cross clamp during coronary bypass procedures.

METHODS

Between November 2001 and August 2002, 206 saphenous vein to aorta proximal anastomoses were created in 132 patients using the Symmetry device. All procedures were performed as part of off-pump coronary artery bypass surgery without any aortic clamping. Intraoperative variables and postoperative data were collected and analyzed retrospectively.

RESULTS

All 206 anastomoses (100%) were successfully completed with the connector. Severe atherosclerotic disease of the aorta was documented in 16 patients (12%). Four anastomoses (2%) required additional suture placement. Predeployment problems occurred with 3 grafts (2.5%) during loading of the connector. Average number of distal bypasses was 3.2 per patient. One patient (0.7%) required reoperation for bleeding from a proximal anastomosis. Six patients (4.5%) had perioperative myocardial infarction documented by electrocardiographic changes. Thirty-day operative mortality was 3% (4 patients). Intraoperative transit time flow measurement was performed in all cases (100%). Postoperative angiography in 43 patients at a median 3 months postoperatively revealed occlusion of 9 of the 81 saphenous vein grafts (11%).

CONCLUSIONS

The initial experience with a proximal saphenous vein graft to aorta anastomosis using the Symmetry connector demonstrates safety and ease of use. There is however some concern with early graft closure. A prospective randomized study is needed to clarify these concerns.

Stapled coronary anastomosis with minimal intraluminal artifact: The S2 Anastomotic System in the off-pump porcine model

OBJECTIVE

A reliable, easy-to-use, 1-shot anastomotic device will significantly push the barrier for less invasive coronary bypass surgery. The current study was designed to test the safety, efficacy, and early patency of a novel distal anastomotic device.

METHODS

The S2 Anastomotic System (iiTech BV, Amsterdam, The Netherlands) was used in 10 consecutive pigs (73 kg) on a mild antiplatelet regimen. In each animal, the device was used to create an internal thoracic artery to left anterior descending bypass on the beating heart. The anastomoses were evaluated intraoperatively (n = 10), at 2 days (n = 2), and at 5 weeks (n = 8) by functional flow measurements, postmortem angiography, and histomorphologic examination.

RESULTS

In all pigs, the S2 Anastomotic System rapidly created successful anastomoses at the first attempt (graft loading and coronary ischemia time: 1.2 +/- 0.3 minutes and 3.0 +/- 0.6 minutes) on target vessels of 1.6 to 2 mm inner diameter. There were no technical failures or anastomotic leaks requiring additional sutures. Both intraoperatively and at the time of death, ischemically induced peak hyperemic flow responses demonstrated widely patent bypasses, which were confirmed by postmortem angiography (FitzGibbon grade A, n = 10) and macroscopic evaluation (anastomotic orifice: 2 mm). Histomorphologic evaluation showed a normal healing response with negligible neointima covering the connector and limited streamlining repair tissue formation between the staple-like elements of the connector.

CONCLUSIONS

The S2 Anastomotic System consistently created automated, fast, and reliable internal thoracic to coronary artery anastomoses on the porcine beating heart with excellent graft patency and healing characteristics at the 5-week follow-up.

Coronary anastomotic devices: blood-exposed non-intimal surface and coronary wall stress

OBJECTIVE

This study compares the area of blood-exposed non-intimal surface in device-constructed anastomoses with the conventionally sutured anastomosis and examines the technical feasibility of 0 blood-exposed non-intimal surface anastomosis configurations.

METHODS

In the device-constructed anastomosis, blood-exposed non-intimal surface was estimated in all anastomosis configurations identified in truly new (ie, nonduplicate and nonrelated) patent applications and in anastomotic devices recently introduced by several institutions. In the sutured anastomosis, blood-exposed non-intimal surface area was estimated by analysis of previously investigated anastomoses. In 0 blood-exposed non-intimal surface anastomosis configurations, finite element modeling was used to calculate coronary wall stress.

RESULTS

By the end of 2001, 57 truly new applications for the distal coronary anastomosis had been published, categorized in 11 types of anastomosis configurations. The tissue blood-exposed non-intimal surface area (ie, non-intimal tissue surface area) ranged from 0 to 6 mm(2). Approximate total blood-exposed non-intimal surface areas (ie, sum of tissue blood-exposed non-intimal surface and foreign body surface area) in recent devices are 80 mm(2) (GraftConnector, Jomed, Helsingborg, Sweden); 33 mm(2) (Magnetic Vascular Positioner rings, Ventrica, Inc, Fremont, Calif); 4.3 mm(2) (distal connector of St Jude Medical, Inc, St Paul, Minn); and 0.3 mm(2) (Crinoline frame, University Medical Center Utrecht/Delft University of Technology, The Netherlands). The sutured anastomoses, in contrast, contained approximately 1.3 mm(2) blood-exposed non-intimal surface area. The mean peak porcine coronary wall stress in 0 blood-exposed non-intimal surface anastomosis configurations with greater than 90 degrees arteriotomy edge eversion ranges from 0.4 to 0.8 N/mm(2) compared with the mean porcine coronary tear stress of 0.8 N/mm(2).

CONCLUSIONS

In recently introduced devices for clinical use, the total blood-exposed non-intimal surface area ranges from 4.3 to 80 mm(2) compared with 1.3 mm(2) in sutured anastomoses. The blood-exposed non-intimal surface area depends on anastomotic orifice size, wall thickness, and bonding components' location and size. Deforming the coronary wall to most of the 0 blood-exposed non-intimal surface anastomosis configurations leads to dangerously high stress concentrations in the coronary arteriotomy corners.

Assessment of an aortosaphenous vein graft anastomotic device in coronary surgery: clinical experience and early angiographic results

BACKGROUND

Until now technologic evolution in coronary bypass surgery has focused on extracorporeal circulation, on operation without extracorporeal circulation, and on the exposure of the operative site. Recently a one-shot anastomotic device for the proximal anastomosis in coronary surgery was developed. We investigated whether the use of the aortic connector system (ACS) could facilitate the creation of aortosaphenous vein graft anastomoses in myocardial revascularization.

METHODS

From November 2000, 40 ACS devices were used in 36 consecutive patients (mean age 70.7 +/- 8.9 years); 12 patients (33.3%) underwent surgery on pump and 24 patients (66.6%) off pump; 50 distal anastomoses were performed. In all cases the connection with the ascending aorta was created before the distal anastomoses because of the necessity to slide the saphenous vein graft (SVG) over the vein transfer sheath. Intraoperative graft function was tested measuring blood flow by Doppler analysis. Postoperative evaluation of the anastomotic patency was carried out by early angiography in 34 patients (94.7%) but was excluded in 5 patients (5.3%) with extensive extracardiac vascular occlusive disease.

RESULTS

Of 38 AC (95%) evaluated, 36 (94.7%) functioned properly. The end-to-side proximal anastomosis without aortic clamping is instantaneous, the quality of anastomoses was highly rated, no additional stitches were required, and all coronary arteries could be reached. Intraoperative quantity flow was measured by Doppler analysis and all but one showed good flow. Early postoperative angiography demonstrated good patency of the grafts in all cases but 2 (5.3%). At 1-year follow-up, 1 patient died of stroke; all other patients remained free of symptoms and no reoperation was required.

CONCLUSIONS

The use of ACS makes end-to-side anastomosis rapid, effective, and reproducible while eliminating aortic cross clamping; it opens a new era in beating or nonbeating coronary surgery. Long-term results are mandatory to confirm our favorable preliminary results.

The Heartflo device for distal coronary anastomoses: clinical experiences in 60 patients

BACKGROUND

The Heartflo anastomotic device automates the suturing process with simultaneous delivery of 10 standard polypropylene sutures through the graft and the coronary vessel wall to construct the anastomosis. We performed clinical testing in 60 patients undergoing coronary artery bypass grafting.

METHODS

One automated distal coronary anastomosis was initially placed in each patient, the other anastomoses were created with standard running sutures. After a "flat foot"-shaped prototype was deployed in 30 patients (group I), the design of the foot was modified and deployment of the new device performed in the next 30 patients (group II).

RESULTS

In group I, automated anastomoses were completed in 16 patients (53%) using 1.7 +/- 1 additional stitches. In 26 group II patients (86%), a hemostatic anastomosis using 1.2 +/- 1 additional stitches was achieved. Anastomoses were completed in 19.0 +/- 3 minutes in group I and in 15.6 +/- 2 minutes in group II.

CONCLUSIONS

We have shown the feasability of coronary anastomoses using the Heartflo device. The modified version improved tissue capture, resulting in a higher rate of completed anastomoses. Because anastomotic time is still prolonged, an easier suture management is mandatory in the next developmental step.

Two generations of the St. Jude Medical ATG coronary connector systems for coronary artery anastomoses in coronary artery bypass grafting

BACKGROUND

In the past, coronary anastomoses have been performed using running and, occasionally, interrupted non-resorbable sutures. Recently, special interest has developed in mechanical anastomotic devices to facilitate minimal invasive techniques or limited access surgery. The experience with two series of patients undergoing coronary artery bypass grafting (CABG) using the St. Jude Medical ATG coronary connector systems (investigational stainless steel device, not yet commercially available) for vein-to-coronary artery anastomoses is reported here.

METHODS

Between November 2000 and April 2002, we evaluated two generations of distal coronary connector systems in 19 patients who were scheduled for multivessel CABG. One vein graft-to-coronary artery anastomosis per patient was performed with a stainless steel mechanical connector, in an ongoing investigational study. Although these two generations of the St. Jude Medical ATG coronary connectors have the same underlying construction, somewhat cumbersome loading of the first-generation system led to simplification of the second-generation system, which is currently evaluated.

RESULTS

With the first generation of distal connector, hemostasis was instantaneous in all cases, and all anastomoses were patent at the end of the procedure. However, retrograde flow to the native coronary artery was restricted in 1 patient. The connector was removed, and the anastomosis was performed with a running suture at the same site. Three-month angiography or magnetic resonance imaging angiography was available in 11 patients with 10 patent connector grafts. With the second-generation connectors one of five had to be removed because of leakage, and the anastomosis could be sutured at the same site. The other four connector anastomoses were patent and hemostatic at the end of the procedure.

CONCLUSIONS

The St. Jude Medical ATG coronary connector system is an effective device for sutureless vein graft to coronary artery anastomoses in CABG. The second-generation system presents a further development eliminating some drawbacks of the first generation such as cumbersome, time-consuming loading as well as suitability for smaller coronary arteries. These connectors allow construction of geometrically round anastomoses and theoretically may also be suitable for sequential anastomoses. After tremendous research and development efforts, an optimized mechanical connection system for small vessel anastomoses has been introduced into clinical investigation. This represents a major step in the era of sutureless vascular connections in cardiac surgery.

Avoiding aortic clamping during coronary artery bypass using an automated anastomotic device

In its current application, off-pump coronary artery bypass grafting (OPCAB) requires clamping of the aorta to perform the proximal anastomosis. One of the important theoretical advantages of OPCAB is to avoid the undesirable effects of cross-clamping of the aorta. We report our early experience with a technique of no aortic clamping using the St. Jude aortic connector system in 11 patients.

Unconventional vessel wall apposition in off-pump porcine coronary artery bypass grafting: low versus high graft flow

OBJECTIVE

Facilitated coronary anastomosis techniques may involve unconventional vessel wall apposition in contrast to standard intima-intima apposition. We assessed the patency, anastomotic thrombus formation, and intimal hyperplasia of unconventional intima-adventitia apposition versus conventional suturing techniques in beating heart coronary bypass grafting under low versus high graft flow conditions.

METHODS

The intima-adventitia (n = 28) and conventional anastomoses (n = 28) were evaluated intraoperatively (n = 56), at 4 hours (n = 20), and at 5 weeks (n = 36) in a new off-pump low-flow (n = 28) and high-flow (n = 28) porcine bypass model (< or = 15 mL/min and about 60 mL/min, respectively). The anastomoses were assigned to the animals by means of randomized stratification and examined by means of flow measurements, angiography, and histology.

RESULTS

Mean graft flows in intima-adventitia and in conventional anastomoses were similar (P =.709). All but 1 of 56 anastomoses (low flow conventional) were fully patent at the time of death. At 4 hours, only small platelet depositions were found at the exposed media and adventitia in the unconventional anastomoses. At 5 weeks, little streamlining intimal hyperplasia was found, which was comparable between the anastomoses (P =.600).

CONCLUSIONS

In low-flow conditions (< or = 15 mL/min) unconventional intima-adventitia apposition was not detrimental to the internal thoracic-coronary artery anastomosis in the pig. This finding may expand design strategies of facilitated coronary artery bypass anastomosis techniques.

Early clinical experience with a new sutureless anastomotic device for proximal anastomosis of the saphenous vein to the aorta

BACKGROUND

Avoiding aortic side clamping is useful to avoid local particulate embolization. A device that allows a saphenous vein graft to be anastomosed to the aorta without aortic manipulation is clinically evaluated.

METHODS AND RESULTS

From July 1999 to March 2000, 17 patients who underwent myocardial revascularization had an aorta-saphenous vein graft anastomosis performed by means of an aortic anastomotic device. Eight were operated on with cardiopulmonary bypass and 9 without. The proximal anastomoses created by the aortic anastomotic device were performed before the institution of cardiopulmonary bypass or before the related distal anastomosis was performed. In 11 patients transcranial Doppler ultrasound was used. In 1 (6%) patient the saphenous vein graft was not deployed, and in 2 (12%) a single suture was added for minor bleeding. None of the 11 patients evaluated with transcranial Doppler ultrasound had evidence of particulate embolization during the procedure. No patient died or was reoperated on for bleeding. Six (35%) patients had a postoperative angiogram 48 +/- 26 days after the operation that showed widely patent proximal anastomoses.

CONCLUSIONS

Use of an aortic anastomotic device allows a sutureless anastomosis to be created between the aorta and saphenous vein graft. The device could be used in totally endoscopic myocardial revascularization. A second-generation device is ready to solve the problems encountered and to increase the ease in handling the device.

Sutureless mechanical anastomosis of a saphenous vein graft to a coronary artery with a new connector device

Construction of vascular anastomoses by manual suturing is a highly skilled and time-consuming procedure. The St Jude Medical Anastomotic Technology Group has developed a sutureless mechanical anastomosis device, which, when tested in animals, produced anastomoses in less than 3 min and with little training. Here we present the results of the first clinical saphenous-vein to coronary-artery anastomosis by means of this device.

Improved vascular tissue fusion using new light-activated surgical adhesive on a canine model

Newly developed light-activated surgical adhesives have been investigated as a substitute to traditional protein solders for vascular tissue fusion without the need for sutures. Canine femoral arteries (n = 14), femoral veins (n = 14), and carotid arteries (n = 10) were exposed, and a 0.3-0.6 cm longitudinal incision was made in the vessel walls. The surgical adhesive, composed of a poly(L-lactic-co-glycolic acid) scaffold doped with the traditional protein solder mix of bovine serum albumin and indocyanine green dye, was used to close the incisions in conjunction with an 805 nm diode laser. Blood flow was restored to the vessels immediately after the procedure and the incision sites were checked for patency. The new adhesives were flexible enough to be wrapped around the vessels while their solid nature avoided the problems associated with "runaway" of the less viscous liquid protein solders widely used by researchers. Assessment parameters included measurement of the ex vivo intraluminal bursting pressure 1-2 h after surgery, as well as histology. The acute intraluminal bursting pressures were significantly higher in the laser-solder group (>300 mmHg) compared to the suture control group (<150 mmHg) where four evenly spaced sutures were used to repair the vessel (n = 4). Histological analysis showed negligible evidence of collateral thermal damage to the underlying tissue in the laser-solder repair group. These initial results indicated that laser-assisted vascular repair using the new adhesives is safe, easy to perform, and contrary to conventional suturing, provides an immediate leak-free closure. In addition, the flexible and moldable nature of the new adhesives should allow them to be tailored to a wide range of tissue geometries, thus greatly improving the clinical applicability of laser-assisted tissue repair.

Comparison of titanium vascular closure staples with suture repair of the thoracic aorta in swine

OBJECTIVE

Devices that reduce technical difficulty and anastigmatic time when repairing large vessels such as the thoracic aorta would be beneficial. The aim of this study was to determine if titanium vascular closure staples (3 mm) could be safely and quickly applied in the repair of large vessels such as the thoracic aorta.

DESIGN

Through a left thoracotomy in 10 female swine (110 to 130 lb), an interposition graft (14 to 16 mm textile) was placed into the aorta distal to the left subclavian artery. Animals were randomized at the time of repair to either running sutures (n = 5; 6-0 polypropylene) or vascular closure staples (n = 5; 3 mm). The anastomosis was evaluated after 2 months with aortograms, and the aorta was harvested to evaluate healing.

RESULTS

The clamp times (mean +/- SD) were 30.8 +/- 8.2 min for suture repair and 24.8 +/- 5.1 min for vascular closure staple repair (p = 0.2). Anastomosis times were 20. 0 +/- 6.2 min for the suture group and 16.4 +/- 6.4 min for the vascular closure staple group (p = 0.4). Arch aortograms at 2 months revealed no significant difference in luminal narrowing between the two groups. Gross and microscopic examination revealed no thrombosis, well-healed wounds with a continuous intimal layer, and no differences in intimal thickness or inflammation between the two groups.

CONCLUSION

Vascular closure staples were equivalent to sutures in terms of durability, graft patency, and wound healing at 2 months. Vascular closure staples may offer the trauma surgeon a quick and easy alternative when repairing large vessels such as the thoracic aorta.

Coronary anastomotic devices: theory and patented ideas on micromechanical fastening

Coronary anastomotic devices are being designed to reduce the laborious, complex suturing approach to endoscopic coronary surgery. An anastomotic device should be safe and reliable, it should allow full view of the vessel parts to be bonded, it must provide a simple and rapid deployment, and should be hemodynamically adequate. Three anastomotic device categories found in the (patent) literature are discussed that use micromechanical fastening techniques. First, devices using individual bonding elements; second, devices using bonding elements anchored to extra-luminal frames; third, devices using an internal frame, often a stent-like structure. Anastomotic devices described in the (patent) literature to date fail to meet all requirements for endoscopic coronary application.

Arteriotomy closure by glued patch in the porcine carotid artery

BACKGROUND

A thoracoscopic approach to coronary bypass grafting warrants renewed search for facilitated vascular anastomosis methods. We reassessed tissue adhesion, sealing properties, and histotoxicity of iso-butyl-cyanoacrylate, in a simplified anastomosis model.

METHODS

In 12 Dutch landrace pigs, five arteriotomies were made in each carotid artery. The arteriotomies were closed by conventional microvascular suturing or by pericardial patch (Peri-Strips) and iso-butyl-cyanoacrylate. The animals were sacrificed at 2 hours (n = 2), 2 days (n = 5), and 4 weeks (n = 5). The arteries were examined by flow measurement, angiography, and histologic analysis.

RESULTS

The time required to close arteriotomies by conventional suturing was 257 +/- 43 seconds (mean +/- SD) and by glued patch 51 +/- 27 seconds (p < 0.001). In all arteriotomies covered by glued patch, complete hemostasis was obtained. At 2 days and 4 weeks, with both methods the same histologic results were observed. At follow-up, all carotid arteries were patent without stenoses.

CONCLUSIONS

Arteriotomy closure by glued patch was simple, fast, reliable, and without signs of histotoxicity. Adhesives deserve to be reconsidered as an alternative to suturing in closed chest beating-heart coronary surgery.

Assessment of patented coronary end-to-side anastomotic devices using micromechanical bonding

BACKGROUND

Despite multiple patented ideas for vascular end-to-side anastomotic devices, and the growing need for them in minimally invasive coronary bypass procedures, no device has been evaluated clinically yet. This study assessed patents of micromechanical end-to-side anastomotic devices with respect to application in coronary artery bypass grafting.

METHODS

Patents were categorized with respect to their micromechanical bonding principle. Calculated values for the wall strain during the construction of an anastomosis were compared with the allowable strain for human coronary arteries.

RESULTS

From 51 patents describing vascular anastomotic devices, 11 ideas, categorized into four groups (staples, clips, mounting systems, and intraluminal stent structures), are serious candidates for coronary end-to-side anastomoses. Most ideas use an anvil for proper application of the bonding elements. For small (1.5 mm) coronary arteries, the calculated wall strain was 0.87, exceeding the breaking strain (0.45) in 60- to 79-year-old patients.

CONCLUSIONS

In a coronary anastomotic device, the concept of using an anvil for the application of micromechanical bonding elements is not attractive, because excessive wall strain is likely to occur.

Evaluation of a new device for quick sutureless coronary artery anastomosis in surviving sheep

OBJECTIVE

A new device for performing quick sutureless vascular anastomosis by means of stent technology has recently been developed by Jomed International, Helsingborg, Sweden. The efficacy of this GraftConnector was studied in a sheep model.

METHODS

In adult sheep, a left anterior thoracotomy under the fourth rib extended across the sternum gave good access to the left anterior descending branch (LAD) and the right internal mammary artery (RIMA). On beating hearts, the GraftConnector group had the RIMA connected to the LAD by means of the new device, while the control animals had the same anastomoses sutured with continuous 7-0 polypropylene sutures. The time for completing the anastomosis (ischemic time) was recorded and the blood flow in the RIMA was recorded with the proximal LAD open and closed, respectively. An intra-operative fluoroscopy with contrast injection directly into the graft was done. Finally the proximal LAD was ligated. The surviving animals are to be followed up.

RESULTS

Seven (46%) of the 15 animals operated on with the traditional suturing technique and seven (63%) of the 11 GraftConnector sheep survived the procedures and are to be followed up. The 11 anastomoses done with the GraftConnector were completed in 2.41+/-0.2 min, and the 14 anastomoses sutured with continuous suture were completed in 6.93+/-0.419 min (P<0.0001). The RIMA blood-flows in the two groups were comparable and are presented. All the surviving animals had open anastomoses at fluoroscopy.

CONCLUSIONS

Quick coronary artery anastomoses without suturing on beating hearts can be completed with the new GraftConnector. The GraftConnector creates reproducible anastomoses in much less time than suturing, the per-operative mortality in the GraftConnector Group was accordingly lower. Long-time follow-up of the patency in surviving animals is pending. The presented device may ultimately permit quick anastomoses endoscopically.

Video-assisted replacement or bypass grafting of the descending thoracic aorta with a new sutureless vascular prosthesis: an experimental study

PURPOSE

The feasibility of the video-assisted insertion of a new sutureless vascular prosthesis was studied.

METHODS

Seven sheep, weighing 25 to 35 kg, were operated on under general anesthesia. The animals were intubated with a single-lumen endotracheal tube and placed in the right lateral decubitus position. A thoracoscope was introduced in the 11th intercostal space, and a minithoracotomy (4 to 5 cm) was performed in the seventh intercostal space. After retraction of the lung, a short segment (10 cm) of the descending thoracic aorta was exposed. Our prosthesis was made of Dacron and was specifically designed to be inserted without a suture. After systemic heparinization, the aorta was cross-clamped with two vascular clamps introduced into the thoracic cavity through two 5-mm thoracic incisions. The aorta was either replaced (five cases) or bypass grafted (two cases). At the completion of the procedure, blood pressure was pharmacologically increased (5 mg intravenous bolus of epinephrine), and each anastomosis was checked for bleeding. All animals were killed, and the prosthesis was retrieved for macroscopic examination.

RESULTS

The procedure was completed in each case without extension of the minithoracotomy. Insertion of the prosthesis was easy and fast, and completion of each anastomosis required 10 to 15 minutes. A 3- to 4-mm space between each clip was sufficient for proper attachment. All procedures were performed in less than 120 minutes. No bleeding was observed at the level of each anastomosis, even when a sustained high blood pressure was induced. The proper insertion of the prosthesis and the absence of any anastomotic stenosis was confirmed by means of macroscopic examination.

CONCLUSION

Video-thoracoscopic replacement or bypass grafting of the descending thoracic aorta was easy with this new sutureless vascular prosthesis. Minimally invasive vascular surgery might be facilitated with such a prosthesis. However, long-term animal studies are required before human implantation can be undertaken.

Comparison of Arcuate-Legged Clipped versus Sutured Hepatic Artery, Portal Vein, and Bile Duct Anastomoses

Attempts at improving anastomoses have included the development of stapling techniques. Our purpose was to evaluate arcuate-legged clipped versus standard sutured anastomoses of the hepatic artery (HA), portal vein (PV), and bile duct in a porcine liver transplantation model. Two groups of pigs were studied intraoperatively and 1 day after liver transplantation. A control group underwent sutured anastomosis of PV and HA with polypropylene and of bile duct with polydioxanone (n = 8). An experimental group underwent anastomoses with arcuate-legged clips (n = 8). We analyzed the time to perform anastomosis and flows before and at various time points after anastomosis. In addition, patency and histology of the anastomoses were evaluated 1 day after operation, including a fibrin-thrombosis score, medial injury, and inflammation score. Times to complete HA and PV anastomoses were not different between clipped and sutured groups. However, the time was shorter to complete bile duct anastomosis with clips than with sutures (6.3 ± 1.1 minutes and 13.3 ± 2.0 minutes, respectively). Flows through HA anastomoses were not different between groups, but flow through the PV was higher in clipped compared with sutured anastomosis (P = 0.06). Patency was 100 per cent with no leaks for all three anastomoses in both groups. Histologic data were similar between vascular anastomotic groups. Sutured bile duct anastomoses revealed mild smooth muscle injury in 75 per cent whereas clipped bile duct anastomoses displayed no smooth muscle injury. We conclude that arcuate-legged clipped anastomosis represents a viable option to sutured anastomoses of the PV, HA, and bile duct anastomoses. Bile duct anastomoses were completed in less than half the time and with less tissue damage documented histologically.

A novel one-shot anastomotic stapler prototype for coronary bypass grafting on the beating heart: feasibility in the pig

OBJECTIVE

The nonpenetrating, arcuate-legged clip has proved its ability to provide a high-quality microvascular anastomosis. This study assessed the feasibility of constructing a coronary end-to-side anastomosis on the beating heart with a novel mechanical, sutureless anastomotic device that applies 12 circumferential clips simultaneously.

METHODS

In 14 consecutive pigs (70-90 kg), the left internal thoracic artery (diameter, 3 mm) was grafted to the left anterior descending coronary artery (diameter, 3 mm) by means of a one-shot anastomotic stapler prototype. Endothelial denudation, medial necrosis, and intimal hyperplasia were analyzed quantitatively and compared with those seen in conventionally sutured anastomoses (n = 4).

RESULTS

In 8 of 14 anastomoses, the one-shot anastomotic stapler successfully applied all 12 clips circumferentially across the everted arteriotomy edges. In the remaining, either 1 (n = 4) or 3 and 4 adjoining malaligned clips had to be replaced manually with a single-clip applicator. Coronary occlusion was limited to approximately 3 minutes. At follow-up, all anastomoses were patent angiographically. At 2 days, in 2 of 7 cases, a local coronary dissection was observed, and there was a considerable loss of endothelial cells and medial damage. At 28 days, however, minimal intimal hyperplasia was seen at the anastomotic lining, although more pronounced when compared with conventionally sutured anastomoses.

CONCLUSIONS

The one-shot anastomotic stapler prototype enabled short-occlusive (3 minutes), sutureless end-to-side grafting on the beating porcine heart. In spite of early endothelial and medial damage and 2 local dissections, all anastomoses remained patent with minimal intimal hyperplasia at 4 weeks.

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.

Minimally invasive coronary artery bypass grafting: on the beating heart and via limited access

Minimally invasive coronary artery bypass grafting (MICABG) may be achieved by arterial grafting on the beating heart, without cardiopulmonary bypass, and by operations via limited access. The Second Utrecht MICABG Workshop held October 4-5, 1996, focused on beating-heart coronary immobilization, limited-access thoracoscopic and direct-vision mobilization of the internal mammary artery, limited-access left anterior descending coronary artery grafting, and, finally, facilitated distal anastomosis techniques. It has yielded 33 reports in this supplement. The combined, cumulative experience of a number of participants exceeded 3,000 beating-heart cases, including more than 1,000 with arterial grafting through limited access. The average number of anastomoses per patient ranged from 1.0 to 2.0. Therapeutic strategies are evolving, and dedicated instrumentation is being developed. Randomized clinical trials with angiographic follow-up are required to establish that the reduction in invasiveness of coronary bypass grafting is not achieved at the expense of suboptimal quality of the arterial graft and the distal anastomosis.