We thank the entire surgical staff for excellent technical assistance.

The study conforms to the Declaration of Helsinki. The protocol follows the guidelines of an independent institutional ethics committee, and human biomaterials were obtained after informed written consent (ethics committee approval: A 2018-0037).
1. Positioning of the legs
NOTE: Patient inclusion criteria included a history of coronary artery disease with elective/urgent indication for CABG surgery and the need for harvesting of at least one venous bypass graft for complete revascularization. Patients with debilitating chronic disease, emergency operations, status post-deep vein thrombosis, and active wet gangrene were excluded. Pre- and post-operative procedures were comparable with previously described clinical studies12,13. 28 patients undergoing CABG were included for antegrade endoscopic vessel harvesting of 30 great saphenous veins from the lower leg after informed written consent. A cardiac surgeon certified and experienced with the technique (&#62;200 cases) for the upper leg executed the antegrade EVH of the great saphenous veins from the lower leg.
<ol>
	<li>Organization of the surgical theatre
	<ol>
		<li>Before surgery, ensure supine position of the anesthetized patient on the surgical table following institutional standard procedures for CABG surgery.</li>
		<li>Place the vein harvester on the right side of the patient. Place the surgical team and instrumental set-up for cardiac surgery on the left side of the patient. Place the instrumental set-up for EVH near the end of the table (Figure 1, Figure 2; see Table of Materials).</li>
	</ol>
	</li>
	<li>Specific positioning of the legs
	<ol>
		<li>Place two foam rollers (length: 60 cm, diameter: 12 cm) below the extended legs. Place one half-cylindrical foam roller just above the knee in order to avoid overstretched knees and common peroneal nerve lesions. Then, place another full cylindrical foam roller below the Achilles tendon for lifted and outward rotated foot position (Figure 1A-D).</li>
	</ol>
	</li>
</ol>
2. Minimally invasive surgical access to the vein graft
<ol>
	<li>Access site
	<ol>
		<li>Use institutional standard disinfection procedures with Octenidindihydrochlorid followed by standard sterile covering for aseptic surgical conditions.</li>
		<li>Make one longitudinal skin incision (length: 1.5-2 cm) with a curved scalpel (size 10) on the lower leg. Start the incision with the distance of approximately one index finger above the imagined ankle joint and proceed upwards parallel to the medial margin of the tibia bone (Figure 2C).</li>
	</ol>
	</li>
	<li>Bridging vein harvesting technique
	<ol>
		<li>Obtain minimally invasive access to the great saphenous vein with surgical forceps, dissecting surgical scissors, and an electrosurgical pencil, if necessary. Starting from the skin incision, isolate the vessel 4 cm in each direction using a vessel loop, dissecting scissors, small soft tissue retractor, and Langenbeck hook, applying the standard bridging vein harvesting technique (Figure 2C).</li>
		<li>Continuously check vein quality status and surrounding subcutaneous tissue in the working channel. Visualize in order to avoid injury to the saphenous nerve. Avoid harvesting of progressive varicose veins.</li>
	</ol>
	</li>
	<li>Practical hints
	<ol>
		<li>Make sure that one small finger can easily access the working channel (antegrade). Avoid surgical clipping of side branches at this time.</li>
	</ol>
	</li>
</ol>
3. Antegrade EVH with the optical dissector
<ol>
	<li>Insertion of optical dissector
	<ol>
		<li>Assemble the optical dissector by connecting an extended length endoscope (diameter: 7 mm, length: 48 cm) to an optical camera and dissection tip from the endoscopic vessel harvesting system, according to the manufacturer&#39;s instructions. Moisturize the optical dissector with saline containing heparin (i.e., NaCl + Hep: 5.000 per 200 mL).</li>
		<li>Put the inflatable blocker balloon (also provided by the endoscopic vessel harvesting system and moisturized with NaCl + Hep) over the optical dissector. Gently insert the optical dissector (antegrade) and, after, the inflatable blocker balloon into the wound under permanent optical control of the vein (Figure 2D-F).</li>
	</ol>
	</li>
	<li>Dissection of the vein
	<ol>
		<li>Block the inflatable blocker balloon with room air (10 mL). Flood the working channel with CO2 (flow: 5 L/min, pressure: 15 cm H2O) and indicate to the anesthetic medical staff. Make sure that the working channel is extended by the gas pressure.</li>
		<li>Move antegrade until reaching the imagined proximal medial end of tibial diaphysis using the optical dissector, following the manufacturer&#180;s instructions. Gently dissect the main vessel from a majority of subcutaneous tissue until achieving clear identification of side branches.</li>
		<li>For optimal results, dissect the main vessel through antegrade movement of the optical dissector 1) above of, then 2) below, the main vessel. Then, selectively dissect the side branches, with one side of the vein preserving the perivascular tissue as far as possible, followed by the other side (Figure 2G-I).</li>
		<li>Continuously check vein quality status and mechanical stress in the working channel. Visualize in order to avoid injury to the saphenous nerve. Avoid harvesting of progressive varicose veins.</li>
	</ol>
	</li>
</ol>
4. Antegrade EVH with the optical retractor
<ol>
	<li>Insertion of optical retractor
	<ol>
		<li>Remove the optical dissector from the wound and disconnect the dissection tip.</li>
		<li>Adapt the blocker balloon for the optical retractor and block the working channel with a 5 mL syringe. Assemble the optical retractor by connecting the extended length endoscope to the optical camera and retractor device from the endoscopic vessel harvesting system, which is provided with an internal bipolar electrocoagulation device (power output: level 3-4).</li>
		<li>Use anti-fog fluid for the tip of the endoscope (Figure 3A-C). Again, moisturize the optical retractor with NaCl + Hep before antegrade insertion through the blocked balloon.</li>
	</ol>
	</li>
	<li>Isolation of the vein
	<ol>
		<li>Advance the optical retractor antegrade to the end of the working channel. Release the vein from the surrounding subcutaneous tissue with the retractor device and selectively interrupt side branches with the bipolar electrocoagulation device in a retrograde fashion (Figure 3D-F). Here, the bipolar electrocoagulation device must be positioned with the convex ending away from the main vessel.</li>
		<li>Continuously check vein quality status and mechanical stress in the working channel. Visualize in order to avoid injury to the saphenous nerve.</li>
	</ol>
	</li>
</ol>
5. Vein graft retrieval
<ol>
	<li>Finishing of EVH
	<ol>
		<li>Execute a stab incision in the skin with a sharp scalpel (size 11) at the distal end of the dissected vein (regarding venous flow direction). Insert a smooth (anatomical) clamp through the stab incision and clamp the vein under optical control with the optical retractor.</li>
		<li>Gently retrieve the clamped vein through the stab incision and cut it off proximally (regarding venous flow direction). Thereafter, gently remove the optical retractor through the blocked balloon simultaneously relieving the distal portion of the vein (Figure 3G). Deflate the blocker balloon and remove it from the wound.</li>
		<li>Switch off CO2 and indicate it to the anesthetic medical staff. At this time, use surgical clips and interrupt the remaining side branches before retrieval of the vein graft, if necessary.</li>
	</ol>
	</li>
	<li>Finishing of bridging vein harvesting
	<ol>
		<li>Execute a stab incision in the skin with a sharp scalpel (size 11) at the proximal end of the isolated vein approximately 3 cm above imagined ankle joint. Insert an anatomical clamp through the stab incision and retrieve the vein though the skin incision under digital and optical control. Visualize and avoid injury to the saphenous nerve.</li>
		<li>Then, clamp the vein under direct vision and cut off distally (regarding venous flow direction). Thereafter, gently relieve the entire vein graft through the initial minimally-invasive surgical access site and cannulate the proximal end with a 3.0 mm flexible vessel cannula (Figure 3H).</li>
	</ol>
	</li>
</ol>
6. Final preparation of the vein graft
<ol>
	<li>Gently flush the released venous graft with NaCl + Hep (in a 10 mL syringe) alternating with double-clipping of all side branches (Figure 3H). Continuously check vein quality status and repair injuries, if necessary, with polypropylene sutures (7-0 or 8-0). Finally, the vein harvester and primary surgeon must evaluate graft quality of the endoscopic vein, applying the same criteria as is executed for veins harvested by the open technique.</li>
	<li>If necessary, store the vein graft in a NaCl + Hep-moisturized compress at room temperature (RT) for short-term storage. However, avoid longer time periods of storage. Transfer the vein graft into heparinized blood as soon as arterial cannulation for cardiopulmonary bypass is accomplished.</li>
</ol>
7. Wound closure
<ol>
	<li>Ligate the main vessel at both clamped vein ends, each with a 4-0 polyglactin 910 suture. Remove the clamps.</li>
	<li>Insert a 10Fr Redon drain into the wound (Figure 3I). Fixate the Redon drain with 2-0 poly ethylene terephthalate suture at the skin.</li>
	<li>Execute subcutaneous and intracutaneous wound closures at the minimally invasive access site with 2-0 and 4-0 polyglactin 910 sutures, respectively. Close the two small stab incisions at the proximal and distal ends, with one U-suture each, stitched intracutaneously (4-0 polyglactin 910). Drape the wounds with sterile plasters.</li>
	<li>Wrap the leg, except in peripheral artery disease patients.</li>
</ol>

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Manuscript publication was funded by Getinge Group (Germany). Alexander Kaminski is a consultant to Getinge Group and receives speaker honoraria from Getinge Group. All authors declare study conduction and entire scientific analyses were executed independently from industrial partners. All authors declare responsibility for the integrity of the work as a whole and have given final approval to the version to be published. All authors declare that there are no conflicts of interest.

It should be stated that we prefer complete arterial coronary revascularization in our department. There is rising evidence that CABG using bilateral internal mammary artery (IMA) grafts can significantly improve long-term survival of patients14,15,16,17. However, there are valid reasons for a &#34;single IMA plus vein grafts&#34; strategy, especially in patients at advanced ages, patients with high risks for surgical site infection, patients in which the radial artery graft is not available, and in cases with chronically occluded coronary target vessels. In these scenarios, this protocol offers a standardized technique for safe antegrade EVH from the lower leg. Optimal vein grafts for CABG will reduce short-term wound complications and improve long-term outcomes with diminished revascularization and higher quality of life1,2,8.
The protocol is based on three essential pillars: (1) specific positioning of the leg, (2) bridging vein harvesting technique for minimally invasive access site, and (3) antegrade EVH in a tensionless working channel. Sufficient leg positioning prevented interference of optical dissector and retractor with the food, guaranteed undisturbed EVH in the surgical theatre, allowed for easy graft preparation through forward-downward movement of the endoscope in the working channel, and reduced the risk of common peroneal nerve lesions. Sufficient bridging vein harvest technique simplified the insertion of endoscopic devices, reduced the tension in the working channel especially near the access site, and minimized the possibility of vein graft damage through improved movability of optical dissector and retractor. Moisturizing the EVH equipment with heparinized saline further simplified antegrade insertion of the EVH equipment as well as allowed for unimpeded endoscope movements. Instead of systemic heparin infiltration, heparin was administered locally in the working channel, which was sufficient here to prevent from both thrombus formation and bleeding. Most importantly, the tensionless working channel allowed for antegrade EVH with minimal risk for graft injury.
In this procedure, the surgeon&#39;s attention must be concentrated on several aspects. The working channel must be extended by gas pressure before graft preparation. The optical dissector and retractor must be utilized to enlarge the working channel, and the vein harvester may need to enlarge the minimally invasive access site. To the greatest extent possible, the harvester should preserve perivascular tissue (especially near side branches of the vein graft) and be able to use the precise and tissue-protective bipolar electrocoagulation device for interruption of side branches through free movability of the endoscopic vessel harvesting system. In any case, it is recommended to avoid clips in the working channel before EVH. Harvesting beyond the imagined tibial metaphysis requires a higher level of experience, because the working channel becomes progressively narrow and the graft may be damaged.
Some specific tips for successful antegrade EVH include: Avoid bleeding. It is recommended to avoid a narrow working channel. If necessary, the surgeon should use fine surgical forceps to retract the skin incision during material insertion or enlarge the skin incision with the curved scalpel (and fixate the blocker balloon with an additional intracutaneous U-suture). It should be repetitively evaluated if the working channel is extended by the gas pressure and tension-free. The working channel should be enlarged with the optical dissector or retractor, if necessary. The side branches should be sufficiently dissected with the optical dissector. The integrity of the subcutaneous (especially the perivascular) tissue should be preserved as much as possible, addressing both graft injury prevention and maximal reduction of mechanical stress in the working channel. Surgeons should be aware of sufficient interruption of all side branches from the main vessel with the optical retractor. Additional skin incisions will be required if interruption of side branches was incomplete. Surgeons should be &#34;tissue-gentle&#34; through avoidance of extensive traction forces affecting the vein, especially in chronic venous insufficiency, diabetes, peripheral artery disease, obese, and elderly female patients. Antegrade EVH from the lower leg should be stopped, at the furthest, next to the imagined tibial metaphysis.
Following this protocol, the antegrade EVH approach enables &#34;tissue-gentle&#34; vein preparation at the lower leg, with adequate vein graft quality and low risk of wound complication, even in chronic venous insufficiency, diabetes, peripheral artery disease, obese, and elderly female patients3,8,9,10. Initial randomized histological analyses of vein grafts illustrated completely preserved endothelial and vessel wall integrity after all harvesting techniques in the department (open vein harvesting, bridging vein harvesting, antegrade EVH). Moreover, antegrade EVH from the lower leg illustrated vein grafts with low side-branching and adequate matching of conduit and target vessels during CABG. Therefore, it was hypothesized that this approach may be advantageous compared to the antegrade EVH approach from the upper leg in follow-up studies. Vein grafts harvested from the knee and upper leg usually show frequent side branching and occasional mismatching of dilated conduit vessels (diameters above 5 mm) with coronary target vessels, which can create more turbulent intraluminal flow conditions and lead to an increased risk for graft occlusion after CABG11.
Further, the proposed technique may eliminate a majority of wound complications, especially after open vein isolation in the region of the knee where wound healing can be compromised due to tissue tension during post-operative mobilization of the patient. The manuscript lacks a systematic in-depth analysis of vein graft histology and its endothelial functionality. However, initial data point to possible non-inferiority of antegrade EVH compared to other harvesting techniques. The protocol emphasizes maximal protection of the surrounding subcutaneous (especially perivascular) tissue, addressing both preserved graft integrity and reduced mechanical stress in the working channel. Further studies are required on controlling the graft long-term patency. The small sample of patients may implicate that the learning curve is not finished. Therefore, the protocol for antegrade EVH from the lower leg was established and performed by surgeons experienced with the technique for the upper leg, which should guarantee sufficient vein graft quality18,19. Further investigation is warranted.
Antegrade EVH with the endoscopic vessel harvesting system produced additional peri-operative procedural costs during CABG and is not reusable. However, cost efficiency was proven, and the closed tunnel EVH system demonstrates multiple highly appreciated advantages over existing reusable or open EVH techniques2,20. In this set-up, a closed tunnel EVH system was chosen because it offers a long (maximum 35-40 cm), small lumen working channel and allows for antegrade EVH from the lower leg with only one minimally invasive skin incision. A single switch from optical dissector to optical retractor and the integration of directed, precise, and graft-protective electrocauterisation enabled a short time expenditure and optimized cost efficiency, quality of life, and vein graft histology2. Moreover, the antegrade approach can be applied for the full length of the leg if a second small incision (standard incision, recommended by the manufacturer) is added next to the imagined tibial metaphysis. As shown, antegrade EVH of the great saphenous vein can be repeated in the second lower leg. Apart from that, antegrade EVH of the small saphenous vein was enabled through specific positioning of the leg with lifted and inward-rotated foot position and lateral minimally invasive access site in two patients (unpublished data by A. Kaminski, 2018), comparable with the work of Rustenbach et al.21
The introduced antegrade EVH concept for the great saphenous vein from the lower leg illustrates feasibility for straightforward graft dissection and adequate graft quality, indicating a promising clinical perspective for routine use in CABG. The protocol has a steep learning curve in experienced cardiac surgeons. Besides the explained benefits, the antegrade EVH approach for the great saphenous vein from the lower leg displayed low risks for blood stasis, thrombus formation, bleeding, and graft injury, which was previously seen with the conventional retrograde approach. For these reasons, we had cancelled the retrograde approach earlier in patients before starting this study. However, there is a lack of data supporting a general assumption of superiority of the antegrade over the retrograde approach.
Absence of blood stasis (with augmented intravenous blood pressure because of closed venous valves) and limited mechanical stress on the vein may reduce the risk for graft injury and thrombosis as well as improve long-term patency of bypass grafts18,22. The data showed that all great saphenous veins isolated by antegrade EVH were adequate grafts for CABG surgery with respect to general macroscopic and randomly selected microscopic evaluations. However, we discarded distal vein graft parts with major injuries resulting from EVH preparation in an inadequately narrow working channel in the early phase of the learning curve. There were no graft injuries during the last 21 EVH procedures. The cardiac surgeon should not accept inadequate bypass graft material, because in these cases, graft occlusion is more frequent and could worsen clinical outcomes23.
A study by Kodia et al. underlined that currently applied EVH protocols should be advanced in order to improve vein graft quality5. Nonetheless, a recent prospective randomized controlled trial clearly depicted that closed tunnel EVH demonstrated gains in quality of life, superior cost-effectiveness, and minor differences in graft integrity compared to open vein harvesting without affecting major adverse cardiac event (MACE) rate after CABG surgery2. Another prospective pilot study similarly showed improved post-operative physical recovery, better quality of life, and equal MACE rates after CABG with EVH compared to open vein harvesting24. Moreover, the question arises whether or not post-operative outcome after CABG with vein grafts isolated by conventional EVH (in clear majority from the upper leg) may be further enhanced with the described antegrade EVH approach for the lower leg. Follow-up studies are warranted. Experienced surgeons and a structural, protocol-based education of inexperienced colleagues may help maintenance of a higher vein graft quality standard isolated by antegrade EVH and broadening of the technique. Besides isolated and combined CABG scenarios, EVH was also shown to be feasible in elective and high-urgency peripheral bypass grafting scenarios25,26. However, caution should be taken. In high-urgency CABG scenarios, a higher level of experience in EVH is required in order to minimize the time exposure and guaranty adequate vein graft quality.
In conclusion, antegrade EVH from the lower leg is a safe method for the isolation of venous graft material for CABG. Macroscopic evaluation and initial histological analyses demonstrated excellent graft quality with preserved endothelial integrity, and this leads to promising clinical results underlining that the method may be a valid alternative to conventional antegrade EVH from the upper leg. Also illustrated is a steep learning curve in experienced cardiac surgeons and low risks for graft-associated complications. The protocol offers a specific institutional step-by-step procedure for antegrade EVH from the lower leg with practical hints, troubleshooting, and possible solutions. Three essential pillars for success were highlighted: (1) specific positioning of the leg, (2) synergizing with bridging vein harvesting technique for minimally invasive access site, and (3) antegrade EVH in a tensionless working channel under continuously optical control of vein graft quality. Therefore, it is proposed that this protocol may help both cardiac and vascular surgeons in developing optimal approaches for high-quality vein graft isolation.

Open atraumatic &#34;low-touch&#34; and &#34;no-touch&#34; techniques have been developed over the years for harvesting saphenous veins in coronary artery bypass graft (CABG) surgery or peripheral bypass grafting, producing grafts with excellent endothelial integrity and long-term patency. However, wound complications remain a major problem when using the open technique, especially in obese, diabetic, and chronic venous insufficiency patients1,2,3,4. The question arises of how physicians can harvest the saphenous vein with optimal graft quality and reduced risk for wound complications. Endoscopic vein harvesting (EVH) techniques have been proven to be cost-effective, and clinical outcome parameters are comparable with the open technique. However, strategies protecting endothelial integrity, histological structure, and physiological function of vein grafts during EVH are highly appreciated in order to preserve optimal graft quality2. Recent studies have presented superior graft patency after open harvesting compared to endoscopic techniques5. It has also been shown that bridging vein harvest techniques can directly improve vein quality6. Therefore, it is hypothesized that vein graft harvesting may be advanced through synergizing antegrade EVH with minimally invasive bridging vein harvesting, specific leg positioning, and vein isolation in a tensionless working channel.
To date, conventional EVH techniques for harvesting great saphenous veins have used antegrade approaches for the upper leg and retrograde approaches for the lower leg. However, we have experienced limitations of these techniques and hold concerns about graft quality. The great saphenous vein from the knee and upper leg frequently have revealed numerous side branches and occasionally shown dilated vessel diameter, leading to impaired vessel quality and mismatching of conduit and target vessels that can negatively affect long-term graft patency after CABG and re-revascularization rate7,8,9,10,11. In our experience, the retrograde EVH approach for the lower leg has repetitively resulted in prolonged blood stasis inside the vessel (with augmented intravenous blood pressure due to closed venous valves), increased mechanical stress on the tissue, bleeding, thrombus formations, graft damage, and impaired graft quality. Consequently, this standardized protocol was developed for safe antegrade EVH from the lower leg, combining the bridging vein harvest technique for minimally invasive access site with antegrade EVH in a tensionless working channel for adequate vein graft quality.

<table><tbody><tr><td>disposable scalpel (size 11, Pr&amp;auml;zisa Plus)</td><td>Dahlhausen, Germany</td><td></td><td>a</td></tr><tr><td>small curved smooth (anatomical) clamps </td><td>B. Braun Aesculap, Germany</td><td></td><td>b</td></tr><tr><td>toothed (surgical) forceps</td><td>B. Braun Aesculap, Germany</td><td></td><td>c</td></tr><tr><td>surgical scissors </td><td>B. Braun Aesculap, Germany</td><td></td><td>d</td></tr><tr><td>holder for scalpel blade (size 10)</td><td>B. Braun Aesculap, Germany</td><td></td><td>e</td></tr><tr><td>fine smoth (anatomical) forcep</td><td>B. Braun Aesculap, Germany</td><td></td><td>f</td></tr><tr><td>sponge-holding clamp</td><td>B. Braun Aesculap, Germany</td><td></td><td>g</td></tr><tr><td>clipping device</td><td>Fumedica, Switzerland</td><td></td><td>h</td></tr><tr><td>18 Gauge cannula (Sterican)</td><td>B. Braun, Germany</td><td></td><td>i</td></tr><tr><td>light handle</td><td>Simeon Medical, Germany</td><td></td><td>j</td></tr><tr><td>needle holder</td><td>B. Braun Aesculap, Germany</td><td></td><td>k</td></tr><tr><td>tissue retractor</td><td>B. Braun Aesculap, Germany</td><td></td><td>l</td></tr><tr><td>Redon needle</td><td>B. Braun Aesculap, Germany</td><td></td><td>m</td></tr><tr><td>adhesive hook and loop fastener</td><td>M&amp;ouml;lnlycke, Germany</td><td></td><td>n</td></tr><tr><td>extended length endoscope </td><td>Karl Storz, Germany</td><td></td><td>o</td></tr><tr><td>optical cable</td><td>Karl Storz, Germany</td><td></td><td>p</td></tr><tr><td>transparent drap camera cover</td><td>ECOLAB Healthcare, Germany</td><td></td><td>q</td></tr><tr><td>connection cable for electrocauterisation</td><td>Maquet, Getinge Group, Germany </td><td></td><td>r</td></tr><tr><td>gas insufflation set</td><td>Dahlhausen, Germany</td><td></td><td>s</td></tr><tr><td>Fred Anti-Fog Solution </td><td>Medtronic, USA</td><td></td><td>t</td></tr><tr><td>bipolar electrocoagulation device </td><td>Maquet, Getinge Group, Germany </td><td></td><td>u</td></tr><tr><td>monitor (WideView)</td><td>Karl Storz, Germany</td><td></td><td>v</td></tr><tr><td>light source (xenon 300)</td><td>Karl Storz, Germany</td><td></td><td>w</td></tr><tr><td>gas insufflation controller (Endoflator)</td><td>Karl Storz, Germany</td><td></td><td>x</td></tr><tr><td>half-cylindrical foam roller</td><td>Almatros, Gebr. Albrecht KG, Germany</td><td></td><td>y</td></tr><tr><td>full-cylindrical foam roller</td><td>Almatros, Gebr. Albrecht KG, Germany</td><td></td><td>z</td></tr><tr><td>bulldog clamp</td><td>B. Braun Aesculap, Germany</td><td></td><td>aa</td></tr><tr><td>flexible vessel cannula</td><td>Medtronic, USA</td><td></td><td>ab</td></tr><tr><td>vessel loop (Mediloops)</td><td>Dispomedica, Germany</td><td></td><td>ac</td></tr><tr><td>Heparin-Natrium (5000 U) in 200ml saline</td><td>B. Braun, Germany</td><td></td><td>ad</td></tr><tr><td>Langenbeck hooks</td><td>B. Braun Aesculap, Germany</td><td></td><td>ae</td></tr><tr><td>sutures (polygalctin 910, Vicryl 2-0, 4-0; poly ethylene terephthalate, Ethibond 2-0)</td><td>Ethicon, Johnson &amp;amp; Johnson, USA</td><td></td><td>af</td></tr><tr><td>Endoscopic vessel harvesting system, Vasoview Hemopro II</td><td>Maquet, Getinge Group, Germany </td><td></td><td>ag</td></tr><tr><td>Octenidindihydrochloride, Octeniderm</td><td>Schuelke &amp;amp; Mayr GmbH, Germany</td><td></td><td></td></tr></tbody></table>

synergizing antegrade endoscopic with bridging vein harvesting for improvement of great saphenous vein graft quality from the lower leg

Antegrade endoscopic harvesting of autografts for bypass grafting may be an optimal strategy addressing excellent graft quality and reduced post-operative wound complications. This standardized protocol for antegrade endoscopic vein harvesting (EVH) from the lower leg has the potential to be introduced to routine coronary artery bypass grafting (CABG). Patients undergoing CABG surgery are positioned on a surgical table with two additional foam rollers below the extended legs, enabling antegrade EVH from the lower leg. Following minimally invasive surgical access through a bridging vein harvest technique, an endoscopic optical dissector is inserted antegrade into the wound. The main vessel and side branches are dissected under continuous optical control of vein quality status and the working channel. After, an endoscopic optical retractor is inserted with an internal bipolar electrocoagulation device for precise, safe, and tissue-protective interruption of side branches. After release of the vein, the vessel is cut off at the proximal and distal ends under optical control, retrieved from the wound, then cannulated and flushed with heparinized saline. Finally, all side branches of the vein graft are double-clipped. Vascular histology is analyzed in a randomized selection of vein samples. After applying this standardized EVH protocol, the learning curve was shown to be steep, and graft quality was sufficient for coronary artery bypass grafting in every case. There was no conversion to surgical harvesting and low risks for tissue damage and bleeding. Leg positioning and synergizing EVH with bridging vein harvesting improved procedural success and vein graft quality. In our hands, antegrade EVH from the lower leg was feasible, demonstrating straightforward graft dissection as well as adequate macroscopic and microscopic graft quality with preserved endothelial integrity. In conclusion, the introduced technique is safe, shows excellent vein autograft quality, and illustrates feasibility for elective and urgent isolated CABG and combined CABG scenarios.

A steep learning curve was demonstrated for an experienced cardiac surgeon performing antegrade EVH of the great saphenous vein from the lower leg (Figure 4). There were no conversions to surgical harvesting. However, there were four cases of vein injury in the beginning of the learning curve. In three of the four cases, major injuries occurred at the distal portion of the vein because of an inadequately narrow working channel when the surgeon isolated the vein above the tibial metaphysis. Disruption of a major side branch in two cases and dilaceration of the distal vein in one case were observed, leading to discarding of the distal portion of the vein. The remaining vein grafts were adequate for CABG in every case. In one of the four cases, minor injury was observed at two small side branches at the proximal portion of the vein, when surgical clipping of side branches was executed in the working channel before antegrade EVH. These injuries were repaired with polypropylene sutures. Final vein graft quality was macroscopically sufficient for CABG in every case regarding graft length, graft diameter, absence of injury, and vessel wall integrity.
In three randomly selected patients, antegrade EVH (as explained above) was extended by additional open vein harvesting from imagined tibial metaphysis upwards to the distal third of the upper leg. Vein samples (about 3 mm in diameter) used for these studies were taken from excess material near the ankle joint (bridging vein harvesting technique), imagined tibial metaphysis (open harvesting technique), and proximal medial end of the imagined tibial diaphysis (antegrade EVH technique). The samples were blinded to the participating pathologist, fixed in formalin, sectioned transversely, and embedded in paraffin by routine procedures. Hematoxylin and eosin-stained 5 &#181;m sections were prepared for light microscopy, and CD31 immunostains were obtained to demonstrate further that endothelial cells and integrity remained intact.
These randomized blind microscopic analyses revealed an intact vascular morphology (Figure 5A,B) and completely preserved endothelial integrity (Figure 5C) in all analyzed vein samples after antegrade EVH as well as employed conventional alternatives. However, lack of experience and negligence for tissue preservation and vein quality can increase the risk for bleeding and graft injury. Therefore, a continuously optical vein quality control is highly recommended, as well as &#8220;tissue-gentle&#8221; vein isolation and preservation of especially perivascular tissue. In this regard, it should be noted that the lifted and outward-rotated foot position and a prolonged distance from the minimally-invasive access point to the ankle joint (one index finger) remarkably improved forward-downward movability of the endoscope. Consequently, synergizing antegrade EVH with bridging vein harvesting reduced mechanical stress and enhanced vein graft quality during antegrade EVH of the great saphenous vein from the lower leg.
Antegrade EVH from the lower leg was feasible, demonstrating straightforward graft dissection and adequate graft quality. No blood stasis, no thrombus formation, and low risk for bleeding and tissue damage were observed. Leg positioning and synergizing the antegrade EVH with bridging vein harvest technique were the two main factors leading to procedural success. Great saphenous vein grafts from the lower leg showed normal diameters (approximately 3-4 mm). After graft retrieval, veins usually demonstrated slight spasms, comparable to our institutional experiences for conventional vein harvesting techniques. Therefore, matching of vein grafts from the lower leg with cardiac target vessels was deemed appropriate for CABG. Thus, the introduced antegrade approach was applicable for both legs. In two cases, antegrade EVH from both lower legs was successfully executed. No wound complications were experienced in this small initial series. Patient acceptance of the method was high.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/59009/59009fig1.jpg" /> 
Figure 1: Organization of surgical theatre and specific positioning of legs. (A-C) The instrumental set-up for EVH was prepared and placed near the end of the surgical table. (D) The instrumental set-up for cardiac surgery was placed on the left side of the anesthetized patient. Two foam rollers (dotted line, one half-cylindrical foam roller just above the knee, one full-cylindrical foam roller below the Achilles tendon) were placed below the extended legs. Foot position was lifted and outward-rotated for direct vision on imagined ankle joint (short line), expected minimally invasive access site (bold line), and medial margin of the tibial metaphysis (dashed line). a-z are described in the Table of Materials. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59009/59009fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/59009/59009fig2a.jpg" /> 
Figure 2: Minimally invasive surgical access and antegrade EVH allowed safe and unimpeded dissection of the great saphenous vein. (A-C) Following sterile draping of patients, the great saphenous vein from the lower leg was isolated and (C) looped through minimally invasive surgical access via the bridging vein harvesting technique. (D-F) The optical dissector was assembled under sterile conditions (D) and inserted antegrade through the inflatable blocker balloon (solid arrow) into the wound (E,F). (G-I) The protocol allowed for a simplified forward-downward movement (dotted arrow) of the optical dissector during EVH (G,H) without impeding the work of the primary surgeon and surgical nurse (I). aa-af are described in the Table of Materials. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59009/59009fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/59009/59009fig3.jpg" /> 
Figure 3: Following antegrade EVH, all isolated vein grafts demonstrated adequate quality for CABG. (A-E) After removal of the optical dissector the working channel was blocked with a 5 mL syringe (A, arrow), the optical retractor was assembled, prepared with anti-fog fluid (B), and inserted antegrade through the inflatable blocker balloon into the wound (C). Again, the protocol allowed for a simplified and unimpeded forward-downward movement of the optical retractor during EVH (D,E). (F-I) An anatomical clamp was inserted into a stab incision (F, dotted arrow) and used to clamp the main vessel under endoscopic control before retrieval of the distal portion of the vein (G). Thereafter, another anatomical clamp was inserted into a stab incision at the proximal end of the isolated vein (G) followed by complete retrieval of the vein, proximal venous cannulation, clipping of side branches (H, dashed arrow), and wound closure (I). ag is described in the Table of Materials. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59009/59009fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/59009/59009fig4a.jpg" /> 
Figure 4: Learning curve for antegrade EVH from the lower leg. A total of 30 great saphenous veins from the lower leg were isolated from 28 CABG patients using antegrade EVH. The graph illustrates an immediate dynamic reduction in time expenditure (min) starting from insertion of the optical dissector until termination of vein graft retrieval. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59009/59009fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/59009/59009fig5a.jpg" /> 
Figure 5: Antegrade EVH preserved integrity of endothelium and vascular wall. (A-C) Representative images from vein cross sections after antegrade EVH for hematoxylin/eosin staining (A,B), as well as for CD31 immunostaining (C), illustrated normal morphology of vascular wall and completely preserved endothelial integrity, respectively. No differences in histology were detected after comparing all harvesting techniques in the department (open vein harvesting, bridging vein harvesting, antegrade EVH). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59009/59009fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Synergizing Antegrade Endoscopic with Bridging Vein Harvesting for Improvement of Great Saphenous Vein Graft Quality from the Lower Leg at JoVE.com

Synergizing Antegrade Endoscopic with Bridging Vein Harvesting for Improvement of Great Saphenous Vein Graft Quality from the Lower Leg

Presented here is a protocol for antegrade endoscopic vein harvesting from the lower leg, which can safely be introduced in routine coronary artery bypass grafting. Vein grafts present excellent graft quality following this standardized protocol with positioning of the legs, minimally invasive access to the vein, and antegrade endoscopic vein harvesting.

Antegrade endoscopic harvesting of autografts for bypass grafting may be an optimal strategy addressing excellent graft quality and reduced post-operative ...

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Nanyang Technological University

Research

JoVE Journal

Medicine

8.6K Views.  University of Rostock. Ons protocol voor antegrade endoscopische ader oogsten kan de optimale strategie voor het aanpakken van uitstekende ader graft kwaliteit en wond genezing en routine coronaire bypass operatie. Synergizeing antegrade endoscopisch met overbruggingsader oogst technieken maakt minimaal invasieve en weefselbeschermende isolatie van hoge kwaliteit ader grafts van het onderbeen in electieve en dringende gevallen. Plaats voor het begin van de procedure de instrumentale opstelling voor endoscopische ad...

Video: Synergizing Antegrade Endoscopic with Bridging Vein Harvesting for Improvement of Great Saphenous Vein Graft Quality from the Lower Leg

Implantation of Inferior Vena Cava Interposition Graft in Mouse Model

Biodegradable scaffolds seeded with bone marrow mononuclear cells (BMCs) are often used for reconstructive surgery to treat congenital cardiac anomalies. The long-term clinical results showed excellent patency rates, however, with significant incidence of stenosis. To investigate the cellular and molecular mechanisms of vascular neotissue formation and prevent stenosis development in tissue engineered vascular grafts (TEVGs), we developed a mouse model of the graft with approximately 1 mm internal diameter. First, the TEVGs were assembled from biodegradable tubular scaffolds fabricated from a polyglycolic acid nonwoven felt mesh coated with &#949;-caprolactone and L-lactide copolymer. The scaffolds were then placed in a lyophilizer, vacuumed for 24 hr, and stored in a desiccator until cell seeding. Second, bone marrow was collected from donor mice and mononuclear cells were isolated by density gradient centrifugation. Third, approximately one million cells were seeded on a scaffold and incubated O/N. Finally, the seeded scaffolds were then implanted as infrarenal vena cava interposition grafts in C57BL/6 mice. The implanted grafts demonstrated excellent patency (&#62;90%) without evidence of thromboembolic complications or aneurysmal formation. This murine model will aid us in understanding and quantifying the cellular and molecular mechanisms of neotissue formation in the TEVG.

To improve our knowledge of cellular and molecular neotissue formation, a murine model of the TEVG was recently developed. The grafts were implanted as infrarenal vena cava interposition grafts in C57BL/6 mice. This model achieves similar results to those achieved in our clinical investigation, but over a far shortened time-course.

Biodegradable scaffolds seeded with bone marrow mononuclear cells (BMCs) are often used for reconstructive surgery to treat congenital cardiac anomalies. ...

Tissue Engineering by Intrinsic Vascularization in an In Vivo Tissue Engineering Chamber

In reconstructive surgery, there is a clinical need for an alternative to the current methods of autologous reconstruction which are complex, costly and trade one defect for another. Tissue engineering holds the promise to address this increasing demand. However, most tissue engineering strategies fail to generate stable and functional tissue substitutes because of poor vascularization. This paper focuses on an in vivo tissue engineering chamber model of intrinsic vascularization where a perfused artery and a vein either as an arteriovenous loop or a flow-through pedicle configuration is directed inside a protected hollow chamber. In this chamber-based system angiogenic sprouting occurs from the arteriovenous vessels and this system attracts ischemic and inflammatory driven endogenous cell migration which gradually fills the chamber space with fibro-vascular tissue. Exogenous cell/matrix implantation at the time of chamber construction enhances cell survival and determines specificity of the engineered tissues which develop. Our studies have shown that this chamber model can successfully generate different tissues such as fat, cardiac muscle, liver and others. However, modifications and refinements are required to ensure target tissue formation is consistent and reproducible. This article describes a standardized protocol for the fabrication of two different vascularized tissue engineering chamber models in vivo.

Tissue Engineering by Intrinsic Vascularization in an In Vivo Tissue Engineering Chamber

This is a guideline for constructing in vivo vascularized tissue using a microsurgical arteriovenous loop or a flow-through pedicle configuration inside a tissue engineering chamber. The vascularized tissues generated can be employed for organ regeneration and replacement of tissue defects, as well as for drug testing and disease modeling.

In reconstructive surgery, there is a clinical need for an alternative to the current methods of autologous reconstruction which are complex, costly and ...

Bioengineering

The Arteriovenous (AV) Loop in a Small Animal Model to Study Angiogenesis and Vascularized Tissue Engineering

A functional blood vessel network is a prerequisite for the survival and growth of almost all tissues and organs in the human body. Moreover, in pathological situations such as cancer, vascularization plays a leading role in disease progression. Consequently, there is a strong need for a standardized and well-characterized in vivo model in order to elucidate the mechanisms of neovascularization and develop different vascularization approaches for tissue engineering and regenerative medicine.
We describe a microsurgical approach for a small animal model for induction of a vascular axis consisting of a vein and artery that are anastomosed to an arteriovenous (AV) loop. The AV loop is transferred to an enclosed implantation chamber to create an isolated microenvironment in vivo, which is connected to the living organism only by means of the vascular axis. Using 3D imaging (MRI, micro-CT) and immunohistology, the growing vasculature can be visualized over time. By implanting different cells, growth factors and matrices, their function in blood vessel network formation can be analyzed without any disturbing influences from the surroundings in a well controllable environment. 
In addition to angiogenesis and antiangiogenesis studies, the AV loop model is also perfectly suited for engineering vascularized tissues. After a certain prevascularization time, the generated tissues can be transplanted into the defect site and microsurgically connected to the local vessels, thereby ensuring immediate blood supply and integration of the engineered tissue. By varying the matrices, cells, growth factors and chamber architecture, it is possible to generate various tissues, which can then be tailored to the individual patient's needs.

The Arteriovenous AV Loop in a Small Animal Model to Study Angiogenesis and Vascularized Tissue Engineering

We describe a microsurgical approach for the generation of an arteriovenous (AV) loop as a model for analyzing vascularization in vivo in an isolated and well-characterized environment. This model is not only useful for the investigation of angiogenesis, but is also optimally suited for engineering axially vascularized and transplantable tissues.

A functional blood vessel network is a prerequisite for the survival and growth of almost all tissues and organs in the human body. Moreover, in ...

Procedure for Human Saphenous Veins Ex Vivo Perfusion and External Reinforcement

The mainstay of contemporary therapies for extensive occlusive arterial disease is venous bypass graft. However, its durability is threatened by intimal hyperplasia (IH) that eventually leads to vessel occlusion and graft failure. Mechanical forces, particularly low shear stress and high wall tension, are thought to initiate and to sustain these cellular and molecular changes, but their exact contribution remains to be unraveled. To selectively evaluate the role of pressure and shear stress on the biology of IH, an ex&#160;vivo perfusion system (EVPS) was created to perfuse segments of human saphenous veins under arterial regimen (high shear stress and high pressure). Further technical innovations allowed the simultaneous perfusion of two segments from the same vein, one reinforced with an external mesh. Veins were harvested using a no-touch technique and immediately transferred to the laboratory for assembly in the EVPS. One segment of the freshly isolated vein was not perfused (control, day 0). The two others segments were perfused for up to 7 days, one being completely sheltered with a 4 mm (diameter) external mesh. The pressure, flow velocity, and pulse rate were continuously monitored and adjusted to mimic the hemodynamic conditions prevailing in the femoral artery. Upon completion of the perfusion, veins were dismounted and used for histological and molecular analysis. Under ex&#160;vivo conditions, high pressure perfusion (arterial, mean = 100 mm Hg) is sufficient to generate IH and remodeling of human veins. These alterations are reduced in the presence of an external polyester mesh.

Procedure for Human Saphenous Veins Ex Vivo Perfusion and External Reinforcement

The mechanisms leading to the development of intimal hyperplasia (IH) and vein graft failure are still poorly understood. This study describes an ex&#160;vivo system to perfuse human veins under controlled flow and pressure. Furthermore the efficiency of external mesh reinforcement to limit the development of IH was evaluated.

The mainstay of contemporary therapies for extensive occlusive arterial disease is venous bypass graft. However, its durability is threatened by intimal ...

Intraluminal Drug Delivery to the Mouse Arteriovenous Fistula Endothelium

Delivery of therapeutic agents to enhance arteriovenous fistula (AVF) maturation can be administered either via intraluminal or external routes. The simple murine AVF model was combined with intraluminal administration of drug solution to the venous endothelium at the same time as fistula creation. Technical aspects of this model are discussed. Under general anesthesia, an abdominal incision is made and the aorta and inferior vena cava (IVC) are exposed. The infra-renal aorta and IVC are dissected for clamping. After proximal and distal clamping, the puncture site is exposed and a 25 G needle is used to puncture both walls of the aorta and into the IVC. Immediately after the puncture, a reporter gene-expressing viral vector was infused in the IVC via the same needle, followed by 15 min of incubation. The intraluminal administration method enabled more robust viral gene delivery to the venous endothelium compared to administration by the external route. This novel method of delivery will facilitate studies that explore the role of the endothelium in AVF maturation and enable intraluminal drug delivery at the time of surgical operation.

After puncturing the aorta through the inferior vena cava (IVC) to create an aorto-caval fistula in the mouse, solution containing a drug is infused into the IVC via the same needle, followed by incubation. This method enables more robust drug delivery to the venous endothelium compared to the external route.

Delivery of therapeutic agents to enhance arteriovenous fistula (AVF) maturation can be administered either via intraluminal or external routes. The ...

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

A Rabbit Model of Durable Transgene Expression in Jugular Vein to Common Carotid Artery Interposition Grafts

Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, intimal hyperplasia, and atherosclerosis. The goal of this article is to demonstrate a method for placing bilateral venous interposition grafts in a rabbit, then transducing the grafts with a gene transfer vector that achieves durable transgene expression. The method allows the investigation of the biological roles of genes and their protein products in normal vein graft homeostasis. It also allows the testing of transgenes for the activities that could prevent vein graft failure, e.g., whether the expression of a transgene prevents the neointimal growth, reduces the vascular inflammation, or reduces atherosclerosis in rabbits fed with a high-fat diet. During an initial survival surgery, the segments of right and left external jugular vein are excised and placed bilaterally as reversed end-to-side common carotid artery interposition grafts. During a second survival surgery, performed 28 days later, each of the grafts is isolated from the circulation with vascular clips and the lumens are filled (via an arteriotomy) with a solution containing a helper-dependent adenoviral (HDAd) vector. After a 20-min incubation, the vector solution is aspirated, the arteriotomy is repaired, and flow is restored. The veins are harvested at time points dictated by individual experimental protocols. The 28-day delay between the graft placement and the transduction is necessary to ensure the adaptation of the vein graft to the arterial circulation. This adaptation avoids rapid loss of transgene expression that occurs in vein grafts transduced before or immediately after grafting. The method is unique in its ability to achieve durable, stable transgene expression in grafted veins. Compared to other large animal vein graft models, rabbits have advantages of low cost and easy handling. Compared to rodent vein graft models, rabbits have larger and easier-to-manipulate blood vessels that provide abundant tissue for analysis.

This method describes the placement of interposition vein grafts in rabbits, the transduction of the grafts, and the achievement of durable transgene expression. This allows the investigation of physiological and pathological roles of transgenes and their protein products in grafted veins, and testing of gene therapies for vein graft disease.

Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, ...

A Training and Testing System for Performing Vascular Reconstruction In Vitro

Manual vascular reconstruction training is essential for a beginner surgeon. However, an optimal training system for vascular reconstruction in vitro has yet to be developed. In this study, we introduce an in vitro training and testing system using a magnetic anchoring technique with which a trainee can practice manual vascular reconstruction individually. Additionally, this system can also be used to test the quality of the reconstruction. The described system includes a vascular reconstruction training machine, magnetic tractors, and a magnetic suture puller. In this manuscript, we detail an end-to-end vein anastomosis using porcine right and left iliac veins. To identify the potential damage caused by a magnetic suture puller on the suture, we created three groups with six segments of 4-0 polypropylene sutures each: a control group with no intervention on the polypropylene suture, a group in which the polypropylene suture is manually pulled with sterile gloves 20x, and a magnetic puller group in which the magnetic puller pulled the polypropylene suture 20x. These groups were tested by light microscopy and breaking strength tests, and the effect of reconstruction was assessed. In the light microscopy test, the control group was less likely to be damaged (p &#60; 0.05) and the number of damaged points of the manual group and magnetic puller group were similar (p &#62; 0.05). The results of the breaking strength test were compared across groups and no significant difference was observed (p &#62; 0.05). The end-to-end anastomosis of the porcine iliac veins was successfully performed using this training system, and the reconstructed veins could undergo 2.0 kPa perfusion pressure. Using this training and testing system the trainee can practice manual vascular reconstruction in vitro individually with the aid of magnetic tractors and a magnetic suture puller, and the quality of the reconstruction can be tested.

Here we present a training and testing system where a trainee can complete manual vascular reconstruction in vitro individually using a magnetic anchoring technique. The system can also be used to test the quality of reconstruction.

Manual vascular reconstruction training is essential for a beginner surgeon. However, an optimal training system for vascular reconstruction in vitro has ...

A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under Arterial Blood Pressure

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor because of the acceleration of intimal hyperplasia due to the exposure to arterial blood pressure. The present protocol is designed for the establishment of experimental venous intimal hyperplasia by interposing rabbit jugular veins to the ipsilateral carotid arteries. The protocol does not require surgical procedures deep in the body trunk and the extent of the incision is limited, which is less invasive for the animals, allowing long-term observation after implantation. This simple procedure enables researchers to investigate strategies to attenuate the progression of intimal hyperplasia of the implanted vein grafts. Using this protocol, we reported the effects transduction of microRNA-145 (miR-145), which is known to control the phenotype of vascular smooth muscle cells (VSMCs) from the proliferative to the contractile state, into harvested vein grafts. We confirmed the attenuation of intimal hyperplasia of vein grafts by transducing miR-145 before implantation surgery through the phenotype change of the VSMCs. Here we report a less invasive experimental platform to investigate the strategies that can be used to attenuate intimal hyperplasia of vein grafts in revascularization surgeries.

The present protocol aims to experimentally create venous intimal hyperplasia by subjecting veins to arterial blood pressure for developing strategies to attenuate venous intimal hyperplasia following revascularization surgery using vein grafts.

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor ...

Occlusion of the Great and Small Saphenous Vein Using Copolymeric Glue Based on N-Butyl Cyanoacrylate and Methacryloxy Sulfolane

We present the preliminary results of a longitudinal observational study aimed at evaluating the effectiveness and safety at different short- and long-term follow-ups of vascular occlusion of the great saphenous vein (GSV) and small saphenous vein (SSV) affected by severe pathological reflux, using an innovative modified cyanoacrylate surgical glue composed of N-butyl cyanoacrylate and methacryloxy sulfolane (NBCA+MS). Ninety patients, prospectively recruited for 1 year, underwent the study with EcoColor-Doppler (ECD) to evaluate the maximum diameters of the GSV and SSV in the orthostatic position and the reflux time (RT). An RT greater than 0.5 s was considered pathologic. Clinical, etiology, anatomy, and pathophysiology (CEAP) assessment was used for the complete evaluation of each patient in the study. All the patients were treated by NBCA+MS glue to obtain vein occlusion and observed before treatment (baseline; T0), within 6 h after treatment (T1), 1 month after treatment (T2), 3 months after treatment (T3), 6 months after treatment (T4), and 1 year after treatment (T5). Chi-square (&#967;) analysis was performed to evaluate the effectiveness and safety of the treatment. All the patients participated in the entire duration of the study. Complete occlusion was maintained in 100% of patients at T1, 98.9% at T2 and T3, and 97.8% at T4 and T5 (p &lt; 0.001). None of the patients suffered from post-surgical thrombosis. No blue hyperpigmentation, or paresthesia was observed during the entire observation period. Immediately after treatment, 7.7% of patients needed painkillers; 1 week after treatment, 100% of patients returned to normal life. Vascular occlusion of the great or small saphenous vein using NBCA+MS glue is a safe procedure with persistent benefits after a 1 year follow-up. This procedure can be performed with local anesthesia, allowing a quick return to normal life. Thanks to its low invasiveness, the treatment is not painful.

Here, we present a protocol to treat the great saphenous vein (GSV) and the small saphenous vein (SSV) affected by severe pathological reflux, using an original sclerosing and embolizing cyanoacrylate-based glue composed of N-butyl cyanoacrylate and methacryloxy sulfolane (NBCA+MS).

Synergizing Antegrade Endoscopic with Bridging Vein Harvesting for Improvement of Great Saphenous Vein Graft Quality from the Lower Leg

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