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

Summary

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.

Abstract

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.

Introduction

Open atraumatic "low-touch" and "no-touch" 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 patients^1,2,3,4. 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 rate^7,8,9,10,11. 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.

Protocol

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 studies^12,13. 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 (>200 cases) for the upper leg executed the antegrade EVH of the great saphenous veins from the lower leg.

1. Organization of the surgical theatre
   1. Before surgery, ensure supine position of the anesthetized patient on the surgical table following institutional standard procedures for CABG surgery.
   2. 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).
2. Specific positioning of the legs
   1. 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).

2. Minimally invasive surgical access to the vein graft

1. Access site
   1. Use institutional standard disinfection procedures with Octenidindihydrochlorid followed by standard sterile covering for aseptic surgical conditions.
   2. 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).
2. Bridging vein harvesting technique
   1. 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).
   2. 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.
3. Practical hints
   1. Make sure that one small finger can easily access the working channel (antegrade). Avoid surgical clipping of side branches at this time.

3. Antegrade EVH with the optical dissector

1. Insertion of optical dissector
   1. 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's instructions. Moisturize the optical dissector with saline containing heparin (i.e., NaCl + Hep: 5.000 per 200 mL).
   2. 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).
2. Dissection of the vein
   1. 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.
   2. Move antegrade until reaching the imagined proximal medial end of tibial diaphysis using the optical dissector, following the manufacturer´s instructions. Gently dissect the main vessel from a majority of subcutaneous tissue until achieving clear identification of side branches.
   3. 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).
   4. 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.

4. Antegrade EVH with the optical retractor

1. Insertion of optical retractor
   1. Remove the optical dissector from the wound and disconnect the dissection tip.
   2. 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).
   3. 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.
2. Isolation of the vein
   1. 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.
   2. Continuously check vein quality status and mechanical stress in the working channel. Visualize in order to avoid injury to the saphenous nerve.

5. Vein graft retrieval

1. Finishing of EVH
   1. 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.
   2. 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.
   3. 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.
2. Finishing of bridging vein harvesting
   1. 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.
   2. 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).

6. Final preparation of the vein graft

1. 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.
2. 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.

7. Wound closure

1. Ligate the main vessel at both clamped vein ends, each with a 4-0 polyglactin 910 suture. Remove the clamps.
2. Insert a 10Fr Redon drain into the wound (Figure 3I). Fixate the Redon drain with 2-0 poly ethylene terephthalate suture at the skin.
3. 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.
4. Wrap the leg, except in peripheral artery disease patients.

Results

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. D...

Discussion

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 patients^14,15,16,17. However, there are valid reasons for a "single IMA plus vein grafts" strategy, especially in patients at advanced ages, patients with...

Materials

List of materials used in this article

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