Conduit Quality Counts:

CE online Conduit Quality Counts: Endoscopic Vein Harvesting Best Practices and Strategies A Continuing Education Activity Sponsored By Grant Funds Provided By

Welcome to Conduit Quality Counts: Endoscopic Vein Harvesting Best Practices and Strategies (An Online Continuing Education Activity) CONTINUING EDUCATION INSTRUCTIONS This educational activity is being offered online and may be completed at any time. Steps for Successful Course Completion To earn continuing education credit, the participant must complete the following steps: 1. Read the overview and objectives to ensure consistency with your own learning needs and objectives. At the end of the activity, you will be assessed on the attainment of each objective. 2. Review the content of the activity, paying particular attention to those areas that reflect the objectives. 3. Complete the Test Questions. Missed questions will offer the opportunity to re-read the question and answer choices. You may also revisit relevant content. 4. For additional information on an issue or topic, consult the references. 5. To receive credit for this activity complete the evaluation and registration form. 6. A certificate of completion will be available for you to print at the conclusion. Pfiedler Enterprises will maintain a record of your continuing education credits and provide verification, if necessary, for 7 years. Requests for certificates must be submitted in writing by the learner. If you have any questions, please call: 720-748-6144. CONTACT INFORMATION: 2014 All rights reserved Pfiedler Enterprises, 2101 S. Blackhawk Street, Suite 220, Aurora, Colorado 80014 www.pfiedlerenterprises.com Phone: 720-748-6144 Fax: 720-748-6196

OVERVIEW Coronary artery bypass graft surgery is one of the most commonly performed procedures in the United States (US) today. One of the factors critical to positive outcomes for this patient population is the quality of the conduit, or graft, used to bypass the occluded vessels. Although internal mammary arterial and other arterial grafts are used frequently in coronary bypass grafting, the greater saphenous vein is the conduit most often used in the operation. Traditionally, the saphenous vein (SV) was harvested through the use of a long longitudinal incision, or multiple incisions, which contributed to postoperative morbidity. Today, technological advancements in the use of endoscopic vein harvesting techniques offer clinicians exciting new options to obtain a high quality conduit, while reducing the complications associated with open vein harvesting. Therefore, cardiologists, cardiac surgeons, and physician assistants involved in coronary artery bypass procedures must remain aware of the new developments in endoscopic vein harvesting in order to maximize its benefits for the patients. This continuing education activity will provide an overview of the clinical considerations of endoscopic saphenous vein harvesting. A brief overview of saphenous vein and arterial conduits in coronary artery bypass will be presented. Traditional open vein harvesting techniques will be reviewed, including a discussion of the associated patient morbidity. Endoscopic vein harvesting, including technological advancements in this technique, will be discussed. Finally, a review of the literature regarding the clinical benefits of endoscopic vein harvesting will be presented. OBJECTIVES After completing this continuing nursing education activity, the participant should be able to: 1. Analyze the clinical implications of conduit quality in coronary artery bypass procedures. 2. Compare open and endoscopic vein harvesting techniques in terms of preoperative, intraoperative, and postoperative patient outcomes. 3. Assess the clinical benefits of new technologies in endoscopic saphenous vein harvesting. 4. Outline the steps in performing an endoscopic vein harvesting procedure. 5. Evaluate research findings related to the clinical considerations of endoscopic vein harvesting. Intended Audience This continuing education activity is intended for nurses, surgical technologists and other healthcare professionals who are interested in learning more about clinical considerations of endoscopic vein harvesting techniques. 3

CREDIT/CREDIT INFORMATION State Board Approval for Nurses Pfiedler Enterprises is a provider approved by the California Board of Registered Nursing, Provider Number CEP14944, for 2.0 contact hour(s). Obtaining full credit for this offering depends upon completion, regardless of circumstances, from beginning to end. Licensees must provide their license numbers for record keeping purposes. The certificate of course completion issued at the conclusion of this course must be retained in the participant s records for at least four (4) years as proof of attendance. AST Credit This continuing education activity is approved for 4.25 CE credits by the Association of Surgical Technologists, Inc. for continuing education for the Certified Surgical Technologist and Certified Surgical First Assistant. This recognition does not imply that AST approves or endorses and product or products that are discussed or mentioned in enduring material. IACET Credit for Allied Health Professionals Pfiedler Enterprises has been accredited as an Authorized Provider by the International Association for Continuing Education and Training (IACET). CEU STATEMENT As an IACET Authorized Provider, Pfiedler Enterprises offers CEUs for its programs that qualify under ANSI/ IACET Standard. Pfiedler Enterprises is authorized by IACET to offer 0.2 CEUs for this program. RELEASE AND EXPIRATION DATE This continuing education activity was planned and provided in accordance with accreditation criteria. This material was originally produced in June 2014 and can no longer be used after June 2016 without being updated; therefore, this continuing education activity expires in June 2016. DISCLAIMER Accredited status as a provider refers only to continuing nursing education activities and does not imply endorsement of any products. 4

SUPPORT Grant funds for the development of this activity were provided by Terumo Cardiovascular Group AUTHORS/PLANNING COMMITTEE/REVIEWERS Julia A. Kneedler, EdD, RN Program Manager/Reviewer Pfiedler Enterprises Kathryn Major, BSN, RN Program Manager /Planning Committee Pfiedler Enterprises Rose Moss, RN, MN, CNOR Nurse Consultant/Author Moss Enterprises Patrick D. Pepper, PA-C Physician Assistant/Planning Committee/Reviewer Surgical Associates of Lexington Judith I. Pfister, MBA, RN Program Manager/Planning Committee Pfiedler Enterprises Alvaro Rojas-Pena, MD Research Investigator of Surgery/Planning Committee/Reviewer ECMO Laboratory Manager General Surgery Department University of Michigan Health Systems Mark E. Schumacher, PA-C Chief Physician Assistant/Planning Committee/Reviewer Cardiothoracic Surgery Mount Carmel Hospital System Carol J. Wilcox, BS, MA, MT (ASCP) Consultant/Author Pfiedler Enterprises Aurora, CO Aurora, CO Elizabeth, CO Lexington, KY Aurora, CO Ann Arbor, MI Columbus, OH Aurora, CO 5

DISCLOSURE OF RELATIONSHIPS WITH COMMERCIAL ENTITIES FOR THOSE IN A POSITION TO CONTROL CONTENT FOR THIS ACTIVITY Pfiedler Enterprises has a policy in place for identifying and resolving conflicts of interest for individuals who control content for an educational activity. Information listed below is provided to the learner, so that a determination can be made if identified external interests or influences pose a potential bias of content, recommendations or conclusions. The intent is full disclosure of those in a position to control content, with a goal of objectivity, balance and scientific rigor in the activity. Disclosure includes relevant financial relationships with commercial interests related to the subject matter that may be presented in this educational activity. Relevant financial relationships are those in any amount, occurring within the past 12 months that create a conflict of interest. A commercial interest is any entity producing, marketing, reselling, or distributing health care goods or services consumed by, or used on, patients. Activity Planning Committee/Authors/Reviewers: Julia A. Kneedler, EdD, RN Co-owner of company that receives grant funds from commercial entities Kathryn Major, BSN, RN No conflict of interest Rose Moss, MN, RN, CNOR No conflict of interest Patrick D. Pepper, PA-C No conflict of interest Judith I. Pfister, MBA, RN Co-owner of company that receives grant funds from commercial entities Alvaro Rojas-Pena, MD No conflict of interest Mark E. Schumacher, PA-C Consultant to grand fund provider Carol J. Wilcox, BS, MA, MT (ASCP) No conflict of interest 6

PRIVACY AND CONFIDENTIALITY POLICY Pfiedler Enterprises is committed to protecting your privacy and following industry best practices and regulations regarding continuing education. The information we collect is never shared for commercial purposes with any other organization. Our privacy and confidentiality policy is covered at our website, www.pfiedlerenterprises.com, and is effective on March 27, 2008. To directly access more information on our Privacy and Confidentiality Policy, type the following URL address into your browse: http://www.pfiedlerenterprises.com/privacypolicy In addition to this privacy statement, this Website is compliant with the guidelines for internet-based continuing education programs. The privacy policy of this website is strictly enforced. CONTACT INFORMATION If site users have any questions or suggestions regarding our privacy policy, please contact us at: Phone: 720-748-6144 Email: registrar@pfiedlerenterprises.com Postal Address: 2101 S. Blackhawk Street, Suite 220 Aurora, Colorado 80014 Website URL: http://www.pfiedlerenterprises.com 7

INTRODUCTION For many patients, coronary artery bypass graft (CABG) surgery is the only definitive means for treating coronary artery disease. 1 The goal of CABG surgery is to increase perfusion to ischemic myocardial cells distal to the obstructed portion of the coronary artery. 2 Increasing the blood flow to the distal portions of the heart is achieved with bypass grafts, or conduits, that are attached below the narrowed portion of the artery. Commonly used conduits in CABG surgery are the internal mammary arteries, radial arteries, and the greater saphenous vein; however, despite the recent trend of using arterial conduits for coronary revascularization, the saphenous vein (see Figure 1) remains an essential and the most commonly utilized conduit for CABG procedures because it can be tailored to various lengths to fit anywhere across the heart (see Figure 2). Figure 1 Greater Saphenous Vein 8

Figure 2 Saphenous Vein as CABG Conduit CONDUIT QUALITY QUALITY COUNTS COUNTS The success of CABG surgery is dependent on the quality of the conduit selected, primarily its long-term patency. 3,4 Long-term patency of a bypass graft is an important determinant in reducing morbidity and increasing survival after coronary bypass surgery. Graft failure has consequences similar to those of coronary artery disease, including recurrent angina, myocardial infarction (MI), additional revascularization procedures, and premature death. Therefore, obtaining a high quality graft and maintaining its endothelial integrity the structural and functional viability of the endothelium are two critical components of successful surgery, an uneventful postoperative course, and improved long-term survival. The success of CABG surgery is dependent on the quality of the co patency. 3,4 Long-term patency of a bypass graft is an important de increasing survival after coronary bypass surgery. Graft failure has artery disease, including recurrent angina, myocardial infarction (M procedures, and premature death. Therefore, obtaining a high quali integrity are two critical components of successful surgery, an unev long-term survival. OPEN VERSUS ENDOSCOPIC VEIN HARVESTING 9 The necessary length of the saphenous vein is harvested from one o

CONDUIT CHOICES AND PATENCY The choice of conduits is highly dependent upon the particular surgeon and institution. Typically, the left internal thoracic artery (LITA), previously referred to as left internal mammary artery or LIMA, is grafted to the left anterior descending artery and a combination of other arteries and veins is used for other coronary arteries. The right internal thoracic artery (RITA) and the radial artery from the forearm are frequently used. The right gastroepiploic artery from the stomach is less frequently used given the difficult mobilization from the abdomen. According to the Society of Thoracic Surgeons National Cardiac Database, the saphenous vein graft remains the most commonly used surgical conduit in coronary artery bypass grafting (CABG). 5 The most appropriate statistical methods for analyzing reliable patency are debatable and all produce different results creating inaccuracies in reporting patency data although large studies do provide important longitudinal and subset information. The graft patency rate is dependent on a number of factors, including the type of graft used (arterial or venous), the size of the coronary artery that the graft is anastomosed with, and the skill of the surgeon performing the procedure. Arterial grafts are far more sensitive to rough handling than the saphenous veins and may go into spasm if handled improperly. Generally, the best patency rates are achieved with the in-situ left internal thoracic artery (the proximal end is left connected to the subclavian artery) with the distal end being anastomosed with the coronary artery (typically the left anterior descending artery or a diagonal branch artery). Lesser patency rates have been experienced with radial artery grafts and free internal thoracic artery grafts where the proximal end of the thoracic artery is excised from its origin from the subclavian artery and re-anastomosed with the ascending aorta. Originally, the radial artery was used as a free graft similar to that of the saphenous vein graft but more recently has been used as a T or Y graft from the left internal thoracic artery or an extension graft from the distal right internal thoracic artery. Graft Selection 1 Year Patency Rate Left internal thoracic artery 96.1% Right internal thoracic artery 92.0% Radial artery 69.5% Gastroepiploic artery 81.4% Saphenous vein 82.6% Graft selection and 1 year patency rates in patients undergoing coronary artery bypass grafting. Source: Fukui, et al, 6 10

The patency rates of saphenous vein grafts have improved with more careful conduit selection, improved harvesting, and surgical techniques together with risk-factor management. Interval analyses of vein graft patency-showing patency of Saphenous Vein Grafts (SVGs) over 14 years of about 50% (SVG: saphenous vein graft). Source: Shah, et al, 7 OPEN VERSUS ENDOSCOPIC VEIN HARVESTING The necessary length of the saphenous vein is harvested from one or both lower extremities by either a traditional, open longitudinal incision (or series of smaller incisions) or by video-assisted endoscopic techniques. 8 Traditional open vein harvesting (OVH) of the greater saphenous vein has long been an underappreciated component of CABG and is currently being reassessed. 9 Open harvesting, despite meticulous surgical technique, is associated with its own complications and postoperative morbidity including postoperative incisional pain, lower extremity edema, and prolonged recovery; reports indicate that wound complications (ie, excessive wound drainage, cellulitis, fat necrosis, delayed healing) may occur in 20-40% of patients, especially in patients with multiple comorbidities such as diabetes mellitus and peripheral vascular disease. 10,11 In spite of 11

the morbidity associated with open vein harvesting, one study found the mean days of hospital stay were comparable between OVH and endoscopic vein harvesting (EVH) groups of patients. Intraoperative Data and Length of Hospital Stay Total operation Number of Hospital stay Group IMA use GSV injury time (min) vein bypasses (days) OVH 262±45 72 (92.3%) 3 (3.9%) 2.8±0.7 13.3±3.3 EVH 278±55 247 (91.5%) 1 (0.4%) 3.2±0.7 12.8±3.1 P value 0.1617 >0.9999 0.0731 0.0002 0.6379 OVH: open vein harvest; EVH: endoscopic vein harvest; IMA: internal mammary artery; GSV: greater saphenous vein. All data except P values are expressed as mean±sd or n (%). Source: Chou, et al, 12 In an attempt to reduce the associated complications of OVH, endoscopic vein harvesting techniques have been developed. Recent studies have shown a decrease in the morbidity of wound complication by harvesting the saphenous vein endoscopically. 13 Postoperative Wound Condition Group ASEPSIS score Infection (pus) Pain scale Edema Altered sensation Hematoma Dehiscence Drainage Debridement Mobility Total OVH 1.1±1.7 4 (5.1%) 2.9±0.7 3 (3.8%) 1 (1.3%) 1 (1.3%) 1 (1.3%) 2 (2.6%) 3 (3.8%) 0 15 (19.2%) EVH 0.9±1.5 4 (1.5%) 2.5±1.2 1 (0.4%) 2 (0.7%) 1 (0.4%) 2 (0.7%) 1 (0.4%) 3 (1.1%) 0 14 (5.2%) P value 0.6125 0.0474 0.0275 0.0366 0.5341 0.3985 0.5341 0.1274 0.1289 0.0002 OVH: open vein harvest; EVH: endoscopic vein harvest. All data except P values are expressed as mean±sd or n (%). Source: Chou, et al, 14 EVH requires only one small knee incision and one or two stab wounds in the lower extremity and/or upper thigh instead of the long incision or multiple incisions in OVH (see Figure 3). Figure 3 Open Versus Endoscopic Vein Harvesting Incisions OVH EVH ENDOSCOPIC 12 VEIN HARVESTING:

Conduit Quality **Recent debate has challenged the patency rates of vessels harvested endoscopically; two studies were conducted to compare conduit quality between open saphenous vein harvest 15, 16 and those harvested endoscopically. **2009 Endothelial Review Study Results (Equivalency or Superiority) **2010 Endothelial Review Study Results (Equivalency or Superiority) The two studies were almost identical in protocol with the major difference being the endoscopic vein harvesting product. Only after completion of the second study, the authors concluded that the open vessel harvesting or endoscopic vein harvesting technique can offer similiar conduit quality results provided the instrumentation and operator harvesting technique are superior. 13

EVH TECHNIQUE: SYSTEM COMPONENTS AND PROCEDURAL OVERVIEW EVH System Components As noted, EVH is a minimally invasive approach to saphenous vein harvesting through one small knee incision and one or two small stab wounds that minimize scarring, morbidity, and infection associated with a traditional longitudinal incision. EVH techniques have been developed that incorporate specialized technology that improves both the quality of the conduit as well as patient safety; an overview of these technological advancements is presented. (Note: see the Literature Review section below for a discussion of the studies mentioned here.) 5 mm, 5.5 mm, 7 mm rigid endoscope (depending on the system). Non-occlusive trocar. The use of a non-occlusive, clip-on trocar permits steady advancement of the harvester or dissector rods without impeding blood flow at the incision site. The dissector or harvester rod accesses the saphenous vein by entering the nonoccluding trocar through the port. The body of the trocar, once inserted into the leg incision, stays in place with the clip secured to the skin, thereby allowing quick conversion between the procedural steps. Furthermore, this type of trocar places little or no pressure on the vein at the incision site. Research has shown that clot formation can result if stagnant blood (that is not anticoagulated) is allowed to remain within a collapsed saphenous vein. The use of a non-occlusive trocar and continuous perfusion within the SV during EVH assists in lowering the risk of intraluminal clot formation. Dissector rod. A specialized dissector rod is available with an atraumatic, fixed, conical tip which provides consistent and uniform dissection. A unique and patent pending 14

V-Glide dissector with a polytetrafluoroethylene (PTFE) shaft reduces drag when dissecting tissue. This in turn may reduce trauma caused during dissection. In addition, carbon dioxide (CO 2 ) is delivered at the tip, which keeps the tunnel tented for increased visibility, thereby maximizing the field of view. Additionally, the open CO 2 delivery system design helps to reduce the risk of CO 2 embolism. Centering rings also allow the clinician to monitor the location of the dissector cone tip relative to the vein during dissection. Research has shown that vessels harvested endoscopically using a closed EVH insufflation system frequently have more intra-luminal clots; studies have also demonstrated that CO 2 embolisms occur more frequently when a closed CO 2 insufflation system is used; therefore, continuous CO 2 monitoring has been suggested to provide early detection and help prevent the development of significant CO 2 embolisms. Harvester rod. Technological advancements have also resulted in the development of a harvester rod containing a unique mechanism for securing, locking, and cutting the vein. In this type of rod, the keeper mechanism gently encapsulates the saphenous vein in order to minimize potential damage to it during cauterization. Essentially, this mechanism maintains the proper branch positioning by anchoring the branches for optimal tautness during sealing and cutting. A locking mechanism holds the saphenous vein securely in place during harvesting and transection of the branches; once locked it eliminates the possibility of leaving branches uncut during harvesting by ensuring that all branches of the vein are coagulated and cut prior to removal of the harvester rod from the leg. The cutting mechanism provides simultaneous cut and coagulation, with the ground electrode located on the back of the sealing/cutting mechanism, at low energy in order to minimize potential damage to the vein during cauterization. This nonmechanical cutting triad, ie, grounding at the tunnel wall, low wattage, and branch tautness, delivers low targeted energy at the tunnel wall, thereby limiting thermal spread and keeping the site of the cut at the tunnel wall, away from the main conduit. Maintaining a controlled distance between the keeper and cutting mechanisms results in an optimal transection location on the branch, ensuring that sealing and cutting take place near the tunnel wall and not near the conduit; this results in longer branches and also facilitates post-harvesting handling. This technology also allows an automatic response to changes in tissue resistance as the branch is first sealed then cut. In addition, a unique wiper located at the end of the tip of the rod cleans the lens of blood or fat to improve visibility, without adding more 15

fluid in the cavity. In the event of bleeding in the tunnel, a safety spot cautery switch may be used to arrest bleeding. An integrated bipolar cord improves efficiency of electrosurgical branch division and reduces reprocessing time and surgical set up. See Table 1 for a summary of the clinical benefits of EVH techniques. Table 1 Summary of Clinical Benefits of EVH Technique Component Open system insufflation Distal insufflation V-Glide dissector with PTFE shaft Non-occlusive trocar Fixed conical tip (dissector rod) Centering rings Fixed-distance vessel keeper and cautery mechanism Vessel encapsulation Integrated bipolar cord V-cautery Clinical Benefits May lower the risk of CO 2 embolism. May retain vessel moisture. May avoid additional hospital costs associated with air embolism (no longer reimbursed by CMS as of October 2008). Insufflation occurs at the operative site for increased visibility. Reduces drag when dissecting tissue and may lower the risk of trauma during dissection. May lower the risk of intra-luminal clot formation by not occluding blood flow through the vessel. May reduce the risk of blood/fluid collecting in the tip or tip detachment in the tunnel. May avoid additional hospital costs associated with unintended retained foreign object (no longer reimbursed by CMS as of October 2008). May protect the vessel from damage during dis section because the location of the vessel relative to the conical tip is known. Allows optimal transection location on branch to obtain longer branches, facilitating post-harvesting handling of the vessel and positions the seal and cut at the tunnel wall away from the main conduit. Secures the vessel and ensures that all branches are sealed and cut prior to removing the harvester rod. Improves efficiency of electrosurgical branch division and reduces surgical set up and reprocessing time. Safety spot cautery function allows for direct cauterization of areas that have inadvertent bleeding. Endoscopic tower. The endoscopic equipment tower contains the camera processing unit (CPU), light source, CO 2 insufflator, flat panel video monitor, and bipolar electrosurgery generator. 16

PREOPERATIVE EVALUATION Preoperative evaluation can influence hospital quality improvement, hospital/surgeon report cards, and reimbursement. Thus accurate preoperative appraisal can translate into the implementation of proper quality surveillance mechanisms and improve risk-adjusted mortality for CABG to less than 2% for the general population and 3-4% for the Medicare population. The following information is essential to the cardiologist and cardiac surgeon in the evaluation and management of patients prior to cardiac surgery. 17 Physical examination. During the physical examination, particular attention should be paid to the patient s risk for endocarditis, the presence of aortic insufficiency, the presence of vascular disease, and neurologic status. Identification of an aortic regurgitation murmur is important because during cardiopulmonary bypass, regurgitation can worsen, and acute left ventricular distension may develop. Potential issues of concern include prior surgeries that may have injured the conduit of choice whether venous or arterial. The conduit that best matches the size of the coronary arteries should be chosen. Preoperative laboratory evaluation. Basic laboratory testing prior to cardiac surgery should include a complete blood count, coagulation screen, chemistry profile, stool hematest, evaluation of ventricular function, and assessment of coronary anatomy via cardiac catherization. If clotting disorders are detected, the need for heparin should be considered. The use of ultrasound to perform vein mapping may be a consideration in selecting the optimum site for the incision. Preoperative estimation of morbidity and mortality risk. Several scoring systems have been developed to assess perioperative risk. The major risk factors for adverse outcome during CABG include advanced age, emergency surgery, history of prior CABG, dialysis dependency, and creatinine of 2 mg/dl or higher. Risk factors for morbidity and mortality. Preoperative risk assessment is critical to rule out venous or arterial disease to ensure the safe performance of cardiac surgical procedures and the achievement of low mortality rates. Any of the conditions below are risk factors to consider in predicting postoperative outcomes: Atrial Fibrillation; Renal Disease; Age (>70 years old); Ventricular Dysfunction; Pulmonary Disease; Reoperation; Nutrition and BMI; 17

Diabetes; Carotid Artery Disease; and Bradyarrhythmias and Atrioventricular or Intraventricular Block. It is worth noting that patients with peripheral vascular disease (both arterial and venous) have high risk factors for morbidity and mortality after CABG. Occasionally, based on the stage of their disease, CABG or EVH (history of DVT, varicose veins, etc.) may be contraindicated. Open communication between the clinician and team is important to the quality of the conduit and, thus, to the success of the procedure. Discussions are essential between the clinical teams to ensure the best decisions are made regarding preoperative concerns, intraoperative considerations, and postoperative concerns and issues related to vessel grafts and harvest sites. EVH Procedure The general procedural steps in performing EVH are outlined below. Incision: Marking the incision: Palpate the operative leg. Place the tip of the fingers along the tibial edge. Follow the length of the tibial edge to the inferior portion of the knee condyle. Once the fingers reach the knee condyle, trace a 2.5 cm lateral mark with a marking pen one fingerbreadth below the tibial edge (see Figure 4). Figure 4 Marking the Incision Making the incision: Make a transverse incision as indicated. Locate the saphenous vein. Expose and isolate the adventitious layer with vessel loop; clip any branches that are immediately visualized. Place two clips side by side on the branch and cut the branch in between the clips. 18

Dissect proximal and distal to the incision to allow adequate placement of the trocar, approximately 4-5 cm in both directions. Best practice tips 16 : Keep the length of the skin incision to a minimum so the blunt tip of the CO 2 insufflation port at the incision has a good seal. Consider making the above-the-knee incisions transversely and belowthe-knee incisions longitudinally over the vein. When using CO 2 insufflation to improve visibility, use the lowest tunnel pressure possible to minimize the risk of CO 2 embolism. With closed CO 2 insufflation, keep the central venous pressure (CVP) slightly greater than the tunnel pressure to reduce the risk of CO 2 embolization. Dissection: Clip on the trocar: Insert the dissector rod into the leg incision (see Figure 5). Begin the insufflation; advance the conical tip of the dissector rod to separate the saphenous vein from the surrounding fat and tissue. Dissect posterior and then anterior to the vein. This two pass method ensures minimal manipulation while delivering an adequate tunnel to harvest the vein. Figure 5 Insertion of Dissector Rod Best practice tips 18 : Use the same sequence for dissection each time for performing the overall procedure on the leg site and the specific vessels. Use short and gentle motions while advancing the dissecting cannula from side to side along the vessel and around vessels. Ensure that side branches are thoroughly dissected (and long enough to apply suture ties) and allow adequate length during branch division. 19

Harvesting: Insert the harvester rod, proceeding to the distal end from the incision site (see Figure 6). Capture the main saphenous vein in the keeper mechanism; move the rod toward the incision site. Coagulate and cut all the branches. Figure 6 Insertion of Harvester Rod Best practice tips 18 : Establish a regular sequence for the branch division starting at the distal end of the tunnel, working back to the incision. Consider making a fasciotomy along the tunnel if the space is tight. Before dividing the branch, consider whether it is of adequate length to clip or tie. Keep energy settings as low as possible during branch division. Follow manufacturer s protocol for clinical practice. Clinical protocols should include a minimal length of cauterized branch to ensure thermal spread does not reach main branch. Removing the Vein: After all the branches are coagulated and cut, return to the distal end. Perform a stab wound, pull the vein up to the surface of the skin to cut saphenous vein from the keeper mechanism. Remove the harvester rod. Remove the vein (see Figure 7). 20

Figure 7 Removing the Vein Best practice tips 18 : Make sure all branches and connective tissue are free from the vein before removing it. Use an appropriate technique for distal ligation of the vessel. Take care to avoid stretching the vessel when removing it from the EVH tunnel and irrigate with solution according to hospital protocol being careful not to overdistend. Once the vessel is extracted and prepared, place it in the storage solution specified by hospital protocol (ie, isotonic solutions with or without heparin) until the surgeon is ready to use it. It is feasible for the mean length of an endoscopically harvested saphenous vein graft to be 31.5±7.5 cm but the specific length and method of graft harvesting should be determined by the surgeon. Many researchers have studied the minimally invasive techniques for saphenous vein harvesting with a focus on clot formation and its impact on SV structure and function. One pilot study suggests that heparinization before EVH or use of an open CO 2 system are benign changes in practice that can significantly reduce the clot formation within the conduit. 19 Another study concluded that the endoscopic technique involves increased traction on the vein, use of cautery near the vein, and exposure to CO 2 pressure that causes impaired endothelial function of the venous conduits. Randomized controlled trials are needed to determine whether the level of endothelial dysfunction is clinically relevant. 16 The viability and functionality of the endothelial lining is dependent on ph, temperature, distention, and composition of storage solution as well as the technique of harvest. 21

LITERATURE REVIEW: CLINICAL EXPERIENCE WITH ENDOSCOPIC VEIN HARVESTING As noted in the discussion above, a review of the literature reveals several studies which have demonstrated the clinical benefits and positive patient outcomes associated with the use of EVH in comparison to OVH techniques as well as an EVH concern. Several of these studies are summarized below. To better understand the recent clinical studies comparing two EVH devices, a brief description of how these devices work is included prior to the presentation of the clinical study findings: Endoscopic Vessel Harvesting devices differ in their deployment and design of energy delivered for the hemostatic division or cauterization of tissue. Where energy delivery is concerned, the devices in the first study below had two main distinctions, though they were both electrosurgical bipolar devices that require tissue to complete the circuit. One device has an open V-cutter energy delivery mechanism. Here, the electrical energy is first conducted on the active electrode which has a smaller surface area as compared to the ground electrode. Thus, the concentration of current is higher. This causes tissue to be cut or vaporized. The electrical energy flows through the tissue and is directed to the grounding pad where there is a larger surface area. This causes the tissue to be coagulated. The active electrode faces the conduit and the ground electrode faces the tunnel wall. The other device has a closed Bisector energy delivery mechanism. This design is comprised of two loops of wire equal in size and shape. The tissue between them is coagulated and electrical energy is allowed to travel to and from the conduit. The cut is performed using a blade that is depressed once the user activates a button on the device handle. A recent clinical study entitled Quantitation of Thermal Spread and Burst Pressure After Endoscopic Vessel Harvesting: A Comparison of Two Commercially Available Devices was published in the July 2011 edition of The Journal of Thoracic and Cardiovascular Surgery. 20 This study investigated the extent of thermal injury caused by the open V-cutter EVH system and the closed Bisector EVH system in a porcine (pig) model. Superficial epigastric veins and saphenous arteries were exposed in 10 anesthetized swine. All vessel samples (conduits) were harvested randomly with either the open V-cutter or closed Bisector endoscopic vessel harvesting system. Conduits were harvested and saved for either histologic analysis or burst-pressure test. Statistical differences were analyzed by using a Wilcoxon rank sum test in SAS 9.2 software (SAS Institute, Inc, Cary, NC) for thermal spread and a 2-tailed t test with equal variance for burst pressure. When the open V-cutter system was used to harvest the saphenous vein, 21 of 83 samples had no endothelial injury compared with only 3 of 70 samples in the closed Bisector group. Additionally, the average length of thermal spread was significantly shorter (P<.05) in the open V-cutter system group (0.49±0.05 mm) than in the closed Bisector group (0.94±0.19 mm). From the arterial conduits studied, 30 22

W: CLINICAL EXPERIENCE WITH ENDOSCOPIC VEIN HARVESTING cussion above, a review of the literature reveals several studies which have demonstrated the clinical benefits and positive patient outcome use of EVH in comparison to OVH techniques as well as an EVH concern. Several of these studies are summarized below. dy entitled Quantification of Thermal Spread and Burst Pressure After Endoscopic Vessel Harvesting: A Comparison of Two Commercially was published of in 61 the samples July 2011 edition had no of injury The Journal when of Thoracic the open and V-cutter Cardiovascular system Surgery. was This used study compared investigated the extent of thermal o commercially with available only 3 endoscopic of 53 samples vessel harvesting the closed (EVH) systems Bisector in a porcine group. (pig) The model. average The two thermal systems spread used in the study were the copic Vein Harvesting System (Terumo Cardiovascular, Ann Arbor, MI) and the VASOVIEW 6 Endoscopic Vessel Harvesting System (MAQUET perficial epigastric was significantly veins and saphenous shorter arteries (P<.05) were in exposed the open in 10 anesthetized V-cutter system swine. All group vessel samples (0.42±0.08 (conduits) mm) were harvested er a VirtuoSaph compared (Terumo Cardiovascular, with the closed Ann Arbor, Bisector Mich) or group VASOVIEW (1.05±0.04 6 (MAQUET, mm). Inc, The Wayne, open NJ) endoscopic V-cutter vessel system harvesting system. ested and saved for either histologic analysis or burst pressure test. Statistical differences were analyzed by using a Wilcoxon rank sum test resulted in a significantly smaller amount of thermal spread than the closed Bisector AS Institute, Inc, Cary, NC) for thermal spread and a 2 tailed t test with equal variance for burst pressure. When the VirtuoSaph system was saphenous system, vein, 21 of according 83 samples had to no Dr. endothelial Rojas-Pena. injury The compared length with of only thermal 3 of 79 samples injury was in the significantly VASOVIEW 6 group. lower Additionally, th hermal spread for was arterial significantly and venous shorter (P<.05) conduits in the when VirtuoSaph the system open group V-cutter (0.49±0.05mm) device was than in used. the VASOVIEW No significant 6 group (0.94±0.19 erial conduits studied, 30 of 61 samples had no injury when the VirtuoSaph system was used compared with only 3 of 53 samples in the. The average differences thermal spread were was observed significantly in shorter burst (P<.05) pressure in the (pressure VirtuoSaph system required group to (0.42 burst ± 0.08 the mm) sealed compared with the (1.05 ± 0.04 vessel). mm). The The VirtuoSaph length system of thermal resulted spread in a significantly is short smaller in arterial amount and of thermal venous spread conduits than the (0.4-1.1 VASOVIEW 6 system, jas Pena. The length of thermal injury was significantly lower for arterial and venous conduits when the VirtuoSaph device was used. No mm) and depends on the endoscopic vessel harvesting system. Clinical protocols should ces were observed in burst pressure (pressure required to burst the sealed vessel). The length of thermal spread is short in arterial and.4 1.1 mm) and include depends a minimal on the endoscopic length vessel of the harvesting cauterized system. branch Clinical to protocols ensure should that thermal include a minimal spread length does of not the cauterized at thermal spread reach does the not main reach vessel. the main The vessel. results The results of this of study suggest that at least 1 mm is sufficient. this study t 1 mm is sufficient. Measurement of the maximal length of thermal spread. A; Maximal longitudinal distance of coagulation necrosis from the cauterized end of SA samples was measured (dashed arrow, see text Measurement for details). The extent of the of maximal damage to length the adventitia of thermal and tunica spread. media A; (bracket) Maximal corresponded longitudinal with the distance extent of endothelial coagulation damage necrosis of the from tunica the intima cauterized (short arrow). end (Hematoxylin of SA samples and eosin was measured stain, original (dashed magnification arrow, 2003.) see text for details). The extent of damage to the adventitia and tunica media (bracket) corresponded B; Representative blood vessel with thermal with the extent of endothelial damage of the tunica damage affecting predominanty the tunica adventitia (bracket). intima (short arrow). (Hematoxylin and eosin stain, original C; Representative magnification blood vessel 2003.) with B; thermal Representative damage affecting blood the vessel 3 vascular with layers: thermal tunica damage adventitia, affecting media, and predominantly intima (bracket). the tunica (Hematoxylin adventitia and eosin (bracket). stain, original magnification 1003). C; Representative blood vessel with thermal damage affecting the 3 vascular layers: tunica adventitia, media, and intima (bracket). (Hematoxylin and eosin stain, original magnification 1003.) In 2009, Rousou, et al, 18 conducted a study to evaluate the impact of endoscopic saphenous vein harvest (ESVH) on saphenous vein endothelium viability and functionality using three independent techniques: (1) epifluorescence multiphoton microscopy (MPM); (2) immunofluorescence; and (3) biochemical assays. Ten patients scheduled for elective coronary artery bypass surgery underwent the endoscopic saphenous vein harvest procedure for the proximal portion of the vein and open saphenous vein harvest (OSVH) for the distal portion of the vein. For the ESVH portion, CO 2 insufflation was used for visualization and dissection of the tissues around the vein. Once the vein was mobilized, the side branches were cauterized with bipolar cautery. The endoscopic portion of the vein was excised with a stab incision at the groin. The OSVH vein was obtained through an incision in the lower leg as close to the endoscopic incision as possible using the standard No-touch technique. Multiphoton imaging in transmission mode revealed no gross breaks in the endothelium of any of the SV samples analyzed. However, the endothelial layer in the ESVH samples consistently appeared to be stretched or redundant. Mean esterase activity was significantly higher in the OSVH group, indicating greater endothelial cell viability. Calcium mobilization and nitric oxide (NO) production in response to bradykinin stimulation were significantly greater in the OSVH group, indicating that endothelial nitric oxide synthase (enos) 23

dependent vasomotor function is well maintained compared with the ESVH group. Immunofluorescence revealed disruption or decrease in fluorescence of caveolin and enos in the endothelium of the ESVH group in comparison with the OSVH group. Western blot analysis of protein extracts from the SV samples showed substantial decreased amounts of caveolin, enos and vonwillebrand factor (vwf), and a moderate decrease in cadherin in the ESVH group in comparison with the OSVH group. Caveolin is involved in cell signaling, enos generates nitric oxide leading to platelet activation, recruitment, and aggregation and prevents neutrophil-endothelial adhesion, and vwh is involved in the clotting cascade. The findings suggest that ESVH has a detrimental effect on the function and structure of the vein endothelium but more studies are necessary to evaluate the extent of clinical significance. In 2009, Rousou, et al 20 conducted a study to evaluate the impact of endoscopic saphenous vein harvest (ESVH) on saphenous vein endothelium viability and functionality using three independent techniques: (1) epifluorescence MPM; (1) immunofluorescence; and (3) biochemical assays. Ten patients scheduled for elective coronary artery bypass surgery 24 underwent the Endoscopic Saphenous Vein Harvest (ESVH) procedure for the proximal portion of the vein and Open Saphenous Vein Harvest (OSVH) for the distal portion of the vein. For the ESVH portion, CO2 insufflation was used for visualization and dissection of the tissues around the vein. Once the vein was mobilized, the side branches were cauterized with bipolar cautery. The endoscopic portion of the vein was excised with a stab incision at the groin. The OSVH vein was obtained through an incision in the lower leg as close to the endoscopic incision as possible using the standard no touch technique. Multiphoton imaging in transmission mode revealed no gross breaks in the endothelium of any of the SV samples analyzed. However, the endothelial layer in the ESVH samples consistently appeared to be stretched or redundant. Mean esterase activity was significantly higher in the OSVH group, indicating greater endothelial cell viability. Calcium mobilization and Nitric Oxide production in response to bradykinin stimulation were significantly greater in the OSVH group, indicating that enos dependent vasomotor function is well maintained compared with the ESVH group. Immunofluorescence revealed disruption or decrease in fluorescence of caveolin and endothelial nitric oxide synthase (enos) in the endothelium of the ESVH group in comparison with the OSVH group. Western blot analysis of protein extracts from the SV samples showed substantial decreased amounts of caveolin, enos and vonwillebrand factor (vwf), and a moderate decrease in cadherin in the ESVH group in comparison with the OSVH group. Caveolin is involved in cell signaling, enos generates nitric oxide leading to platelet activation, recruitment, and aggregation and prevents neutrophil endothelial adhesion, and vwh is involved in the clotting cascade. The findings suggest that ESVH has a detrimental effect on the function and structure of the vein endothelium but more studies are necessary to evaluate the extent of clinical significance. Multiphoton transmission imaging showing no evidence of endothelial breaks or tears in any of the samples. A stretched endothelial layer was visible Multiphoton in the endoscopic transmission saphenous imaging vein showing harvest samples. (Magnification 320X) no evidence (ESVH _ of endoscopic endothelial saphenous breaks or tears vein harvest; in OSVH any of _ the open samples. saphenous A stretched vein harvest.) endothelial layer was visible in the endoscopic saphenous vein harvest samples. (Magnification 320X) (ESVH _ endoscopic saphenous vein harvest; OSVH _ open saphenous vein harvest.) Multiphoton fluorescence imaging shows esterase activity and endothelial injury in the open saphenous vein harvest (OSVH) and endoscopic Multiphoton fluorescence imaging saphenous vein harvest (ESVH) vein endothelium. Representative images shows of esterase esterase activity activity in the and OSVH endothelial and ESVH injury samples show greater esterase in the activity open saphenous and viability (green vein harvest fluorescence) (OSVH) in the OSVH samples (a) and when endoscopic compared with saphenous the ESVH vein (b). Additionally, harvest in comparison with OSVH (ESVH) samples vein (c), endothelium. ESVH vessels Representative show robust red fluorescence and membrane images damage of esterase (d), in activity endothelial in the and OSVH smooth and vessel regions of the veins. ESVH (Magnification samples show 320.) greater esterase activity and viability (green fluorescence) in the OSVH samples (a) when compared with the ESVH (b). Additionally, in comparison with OSVH samples (c), ESVH vessels show robust red fluorescence and membrane damage (d), in endothelial and smooth vessel regions of the veins. (Magnification 320.) In 2010, Hussaini, et al, 15 determined that it was possible that the injury to the SV endothelium that was observed in the 2009 Rousou study may be related to the extraction technique and as such repeated this study using the entire open V-cutter EVH system, including the trocar, dissector, and harvester components, in order to evaluate the effect of the open V-cutter endoscopic SV harvesting technique on structural and functional viability of SV endothelium using multiphoton imaging, biochemical and immunofluorescence assays. Nineteen patients scheduled for CABG were prospectively identified. Each underwent open V-cutter endoscopic vein harvesting for one portion and No-touch open SV harvesting for another portion of 24

the SV. The segments were labeled with fluorescent markers to quantify cell viability, calcium mobilization, and generation of nitric oxide. Morphology, expression, localization, and stability of endothelial caveolin, enos, von Willebrand factor, and cadherin were evaluated using immunofluorescence, Western blot, and multiphoton microscopy. Morphological, biochemical, and immunofluorescence parameters of viability, structure, and function were well preserved in the open V-cutter group as in the OSVH group. However, tonic enos activity, agonist-dependent calcium mobilization, and nitric oxide production were partially attenuated in the open V-cutter group. In the end it was concluded that in contrast to the previous study, harvesting of the SV using the entire open V-cutter EVH system did not reveal any structural and functional cellular damage. Morphological structure, esterase activity, and endothelial viability were well maintained in the endoscopic samples (open V-cutter EVH), similar to those observed in the corresponding samples harvested by the No-touch open technique. Open V-cutter endoscopic SV harvesting technique preserves the structural and functional viability of In 2010 Dr. Thatte, determined that it was possible that the injury to the SV endothelium that was observed in the 2009 Rousou study may be related to the extraction technique and as such repeated this study using the VirtuoSaph EVH system (Terumo CVS) in order to evaluate the effect of VirtuoSaph endoscopic SV harvesting technique (VsEVH) on structural and functional viability of SV endothelium using multiphoton imaging, biochemical and immunofluorescence assays. Nineteen patients scheduled for CABG were prospectively identified. Each underwent VsEVH for one portion and No touch open SV harvesting (OSVH) for another portion of the SV. The segments were labeled with fluorescent markers to quantify cell viability, calcium mobilization and generation of nitric oxide. Morphology, expression, localization and stability of endothelial caveolin, enos, von Willebrand factor and cadherin were evaluated using immunofluorescence, Western blot and multiphoton microscopy (MPM). Morphological, biochemical and immunofluorescence parameters of viability, structure and function were well preserved in VsEVH group as in OSVH group. However, tonic enos activity, agonist dependent calcium mobilization and nitric oxide production were partially attenuated in VsEVH group. In the end it was concluded that in contrast to the previous study, harvesting of the SV using the VirtuoSaph did not the SV endothelium. reveal any structural and functional cellular damage. Morphological structure, esterase activity and endothelial viability were well maintained in the endoscopic samples (VsEVH), similar to those observed in the corresponding samples harvested by the No touch open technique (OSVH), VirtuoSaph endoscopic SV harvesting technique preserves the structural and functional viability of SV endothelium. V-EVH Multiphoton images of SV in the transmission mode. Endothelium and smooth muscle cells do not show visible damage and remain intact in vessels harvested by both techniques. OSVH: open saphenous vein harvest; V-EVH: Open V-cutter endoscopic harvest. Magnification 400X Figure a. Intact saphenous vein. Figure b. Frozen sections: 40 μ m Multiphoton images of SV in the transmission mode. Endothelium and smooth muscle cells do not show visible damage and remain intact in vessels harvested by both techniques. OSVH: open saphenous vein harvest; VsEVH: VirtuoSaph endoscopic harvest. Magnification 400X Figure a. Intact saphenous vein. Figure b. Frozen sections: 40 μ m V-EVH Representative images showing similar esterase activity and viability (green fluorescence) in both samples (a and b). Both techniques caused minimal visible damage to the vessels as indicated by attenuated red fluorescence in endothelial and smooth vessel regions (c and d). Magnification = 400X. 25

In 2010, Ouzounian, et al, 21 noting that EVH reduces leg wound infections and improves cosmesis after CABG, but that recent data suggested EVH may be associated with reduced graft patency rates, conducted a study to assess the effect of EVH on shortterm and mid-term outcomes after CABG. Data were prospectively collected on all first-time isolated CABG and combined valve/cabg patients with saphenous vein graft between 1998 and 2007 at one medical center. Patients having traditional OVH were compared with patients having EVH. The results were analyzed to examine the riskadjusted impact of EVH on postoperative leg infection, composite in-hospital adverse events, and individual and composite mid-term adverse events. The study included 5,825 patients, of whom 2,004 (34.4%) had EVH; median follow-up was 2.6 years. The results demonstrated that EVH was associated with reduced rates of leg infection, but had no association with either in-hospital or mid-term adverse outcomes. Endoscopic saphenous vein harvest was associated with reduced readmission to hospital for unstable angina. The authors concluded that, while endoscopic saphenous vein harvest is associated with a lower rate of leg infection, it is not an independent predictor of in-hospital or mid-term adverse outcomes; therefore, endoscopic saphenous vein harvest is a safe alternative to OVH for patients undergoing CABG with saphenous vein. Because conventional open saphenous vein harvest for coronary artery bypass graft surgery is often associated with significant pain and morbidity, Au, et al, 22 undertook a study to determine whether endoscopic saphenous vein harvest reduces leg wound morbidity and improves patient satisfaction as compared to open vein harvesting. Between March 2005 and June 2006, 120 patients who underwent isolated CABG were prospectively randomized into EVH (n = 60) and OVH (n = 60) groups; both groups had matched demographic characteristics and risk factors. The authors analyzed leg wound complications, postoperative pain, patient satisfaction, and clinical outcomes. Six patients in the EVH group required conversion to open technique. The patients in the EVH group had significantly fewer leg wound complications at postoperative days three, seven, and 21 than those in the OVH group. Wound pain scores at postoperative days 3, 7, and 21 were significantly lower in the EVH group. Wound numbness was found in 5.7% of the EVH group and 33.3% of the OVH group patients. Major postoperative complications were not significantly different between the groups; however, there was one hospital mortality in the OVH group. The authors concluded that the EVH technique is a safe and effective alternative to OVH with better wound healing, reduced postoperative pain, and wound numbness; however, the high conversion rate to OVH requires further evaluation. In 2008, Chiu, et al, 23 after summarizing the clinical profiles of patients undergoing EVH, concluded that EVH should be considered as the standard of care for saphenous vein harvest. The authors recognized that EVH is a relatively new technique developed to minimize wound and postoperative complications, which has gained patients acceptance and has become popular in cardiac surgical practices; however, because most centers have limited experience with this approach, a clinical profile summary was conducted. Between March 2001 and August 2006,1,348 patients (945 men and 403 women) with a mean age of 67.2 years underwent EVH of the saphenous vein for coronary artery bypass surgery, peripheral artery reconstruction, and miscellaneous conditions. Technical success was achieved in 98.6% of the cases. Two saphenous veins were discarded 26

because of obvious vein injury. The mean harvest time was 45 minutes: 68 minutes for the first 50 cases and 23 minutes for the last 200 cases. Nearly all the patients (98%) had saphenous veins harvested only from the thighs, whereas only 1.5% of the patients had saphenous veins harvested from the lower legs. Postoperative wound complications were experienced by 61 patients; this included 25 tract hematomas, 19 wound dehiscences or poor healing, 16 wound infections, and one overlying skin necrosis. Overall, 13 subsequent revisions were required for these complications. Detectable air embolisms occurred for 143 patients and numbness in the saphenous nerve territory occurred for 169 patients. These findings show EVH of the saphenous vein to be a valid alternative to open saphenectomy, which provides excellent surgical results; therefore, EVH should be considered as the standard of care for saphenous vein harvest. As noted above, residual clot formation within the excised saphenous vein is a recognized sequela of endoscopic vein harvesting. Brown, et al, 19 hypothesized that endoscopic visualization facilitated by sealed carbon dioxide insufflation causes stagnation of blood within the saphenous vein; in the absence of prior heparin administration, this stagnation provokes clot formation. They studied forty consecutive patients having coronary artery bypass grafting using endoscopic vein harvest with either sealed (n = 30) or open (n = 10) carbon dioxide insufflation followed by ex-vivo assessment of intraluminal saphenous vein clot using optical coherence tomography. In the sealed carbon dioxide insufflation group, clot formation was compared with heparin administration before endoscopic vein harvest, either at a fixed dose or titrated to an activated clotting time greater than 300 seconds (preheparinized, n = 20) and without (control, n = 10). Risk factors for clot formation were also assessed. Residual saphenous vein clot was a universal finding in the control veins (ie, sealed carbon dioxide insufflation EVH without preheparinization). At either dose used, heparin given before EVH significantly decreased saphenous vein clot burden. A similar reduction in clot formation was observed when using open carbon dioxide insufflation endoscopic vein harvest without preheparinization. Intraoperative blood loss and blood product requirements were similar in all groups. These results demonstrate that intraluminal saphenous vein clot is frequently found after endoscopic vein harvest. The authors concluded that systemic heparinization before harvest or use of an open carbon dioxide endoscopic vein harvest system are relatively simple changes in practice that can significantly minimize this complication. Burris, et al, 24 also conducted a study examining clot formation during preparation for grafting in endoscopically harvested saphenous vein grafts (SVG). Noting that saline distention at uncontrolled pressures increases graft thrombogenicity and the risk of early failure after coronary artery bypass grafting, a prospective investigation was conducted to define the incidence of intraluminal clot within endoscopically harvested SVG and the effect of attempted removal by saline distention. Endoscopically harvested SVG were intraoperatively prepared for grafting by using saline distention at uncontrolled pressure (n = 24) or without distention (n = 20). Optical coherence tomography, a catheter-based infrared imaging system, was used to identify and characterize intraluminal clot strands in excess SVG segments (the average length of the vein analyzed was 4.9±2.6 cm). These segments were also assessed for luminal tissue factor activity and endothelial integrity. 27

Clot strands were observed in 45.4% (20 of 44) of imaged SVG segments (severity of observed clots was reported as 54%, mild; 32%, moderate; 14%, severe). Compared with grafts distended with saline, vein segments that were not distended displayed significantly higher endothelial integrity and lower tissue factor activity despite having a higher incidence of clot stands. Static flow was observed in veins during endoscopic harvest. The results demonstrated that clot strands of varying severity are a common finding in SVGs after endoscopic vein harvest. Saline distention is not completely effective in removing clot strands and increases overall graft thrombogenicity; therefore, prevention of clot or less traumatic methods of removing the clot are indicated. In 2006, Suzuki, et al, 25 noting that insufflation of CO 2 during the EVH procedures had been reported to affect arterial carbon dioxide tension, but the occurrence of hypercarbia was still controversial, investigated the effects of CO 2 insufflation during endoscopic harvesting of three conduits: the saphenous vein (SV, n = 34), radial artery (RA, n = 14), or internal mammary artery (IMA, n = 7) for coronary artery bypass surgery. The conduit harvesting was performed using a closed EVH system with insufflation of CO 2 maintaining a cavity pressure of 8-10 mm Hg. After insufflation of CO 2, significant elevation of the partial pressure of CO 2 in arterial blood (PaCO 2 ) was found during harvesting of SV (35.4±3.8 to 49.2+7.5 mm Hg) and of IMA (38.0±2.3 to 44.2±3.2 mm Hg), but no significant elevation of PaCO 2 occurred during RA harvesting with the use of a tourniquet. The extent of PaCO 2 elevation in saphenous vein harvesting showed negative correlation with patients body weight, body mass index, and body surface area. The authors concluded that significant hypercarbia occurs during endoscopic harvesting of SV or IMA; therefore, it is recommended that PaCO 2 should be carefully monitored during endoscopic conduit harvesting for coronary artery bypass surgery. Maslow, et al, 26 also assessed the extent of CO 2 absorption during EVH through a prospective observational study at one tertiary care facility of sixty patients (30 EVH and 30 OVH) undergoing isolated coronary artery bypass graft surgery. Hemodynamic, procedural, and laboratory data were collected prior to (ie, baseline data), during, and at the conclusion (ie, final data) of vein harvesting; data were also collected during cardiopulmonary bypass. Statistical analyses demonstrated significant increases in arterial CO 2 and decreases in ph during EVH. These findings were associated with increases in heart rate, mean blood pressure, and cardiac output. Within the EVH group, greater elevations (>10 mm Hg) in PaCO 2 were more likely during difficult harvest procedures; these patients also exhibited greater increase in heart rate. Elevated CO 2 persisted during cardiopulmonary bypass, requiring higher systemic gas flows and greater use of phenylephrine to maintain the desired hemodynamics. The authors concluded that EVH was associated with systemic absorption of CO 2. Greater absorption was more likely in difficult procedures and was associated with greater hemodynamic changes requiring medical therapy. Chiu, et al, 27 undertook a study to determine whether the incidence of CO 2 embolism during EVH with CO 2 insufflation could be reduced with lower CO 2 insufflation pressure. The authors prospectively studied 498 consecutive patients scheduled for elective offpump CABG. The patients were randomly assigned into high and low groups in which 15 28

and 12 mm Hg CO 2 insufflation pressures were used during EVH, respectively. Multiplane transesophageal echocardiography (TEE) with transgastric inferior vena cava view was used to monitor the appearances of CO 2 bubbles. If a burst of many CO 2 bubbles was found by TEE, the CO 2 insufflation would be stopped until a detailed examination of the operative field was conducted. The results demonstrated that the incidence of CO 2 embolisms in the high pressure group of patients was significantly greater than that in the low pressure group. Two episodes of emergent cessation of CO 2 insufflation occurred in the high group of patients. No massive CO 2 embolism with significant hemodynamic alterations occurred in either group. The authors concluded that the incidence of CO 2 embolisms during EVH could be reduced with lower CO 2 insufflation pressure, which, in combination with increased surgical experience and continuous TEE monitoring of the inferior vena cava, helps to reduce the risks of massive CO 2 embolism. In an earlier investigation of CO 2 embolism associated with EVH, Lin, et al, 28 conducted a study to determine the incidence and severity, as well as the time course of CO 2 embolism during endoscopic saphenous vein harvesting with CO 2 insufflation in coronary artery bypass surgery with TEE monitoring. Four hundred three consecutive patients scheduled for off-pump coronary artery bypass grafting surgery or femoral-popliteal artery bypass grafting surgery were prospectively studied. Multiplane TEE with a new transgastric view was used to monitor CO 2 bubbles in the inferior vena cava and hepatic vein. CO 2 embolisms occurred in 17.1% of patients. Minimal, moderate, and massive CO 2 embolisms occurred in 13.1%, 3.5%, and 0.5%, respectively. The occurrence of moderate and massive CO 2 embolisms was frequently associated with the surgical manipulation of branches of saphenous veins. No significant risk factors were identified. The authors concluded that the incidence of significant CO 2 embolism during endoscopic saphenous vein harvesting with CO 2 insufflation procedures was greater than 4%. Continuous TEE monitoring of the CO 2 bubbles in the inferior vena cava is essential in early detection and can help to prevent the development of significant CO 2 embolisms in these patients. Lai, et al, 29 recognizing that open saphenous vein harvesting can be associated with wound complications, incision pain, prolonged convalescence, and poor cosmetic results, compared the outcomes of open and endoscopic vein harvesting for coronary artery bypass grafting at the Texas Heart Institute. They retrospectively analyzed data from 1,573 consecutive coronary artery bypass procedures performed at their institution during a 20-month period. Each procedure included saphenectomy by endoscopic vein harvesting (n = 588) performed by physician assistants, or by traditional open vein harvesting (n = 985) performed by either physicians or physician assistants. The primary outcome variable was the incidence of postoperative leg infections. Both groups were similar in terms of preoperative risk factors. Postoperatively, leg wound infections were significantly less frequent in the endoscopic vein harvesting group (3 out of 588, 0.5%) than in the open vein harvesting group (27 out of 985, or 2.7%). The most common organism involved in leg infections was Staphylococcus (20 out of 30, or 66%); Staphylococcus aureus was present in 14 of 30 infections (47%). Open vein harvesting was the only significant independent risk factor for leg infection. They concluded that endoscopic vein harvesting reduces leg wound infections; the technique is safe and 29

reliable, and should be the standard of care when venous conduits are required for coronary artery bypass grafting and vascular procedures. The authors also noted that, although the transition from open to endoscopic vein harvesting can be challenging in institutions, it can be successful if operators receive adequate training in endoscopic technique and are supported by surgeons and staff. In 2005, Yun et al, 30 compared the six month angiographic patency rates of greater saphenous veins removed during coronary artery bypass grafting with the endoscopic vein harvesting or open vein harvesting techniques. Two hundred patients undergoing nonemergency on-pump coronary artery bypass grafting were prospectively randomized to either endoscopic saphenous vein harvesting or open saphenous vein harvesting. Follow-up angiography of all vein grafts was scheduled at six months. Graft patency and disease grades were assigned independently by two interventional cardiologists. Leg wound healing was evaluated at discharge, one month, and six months for evidence of complications. There were three conversions from endoscopic vein harvesting to open vein harvesting because of vein factors. Leg wound complications were significantly lower in the endoscopic vein harvesting group than the open vein harvesting group (7.4% versus 19.4%). Based on the statistical analysis, endoscopic vein harvesting emerged as the only factor affecting wound complications. The results showed that overall occlusion rates at six months were 21.7% for endoscopic vein harvesting and 17.6% for open vein harvesting. Additionally, there was evidence of significant disease (>50% stenosis) in 10.2% and 12.4% of endoscopic vein harvest and open vein harvest grafts, respectively. After statistical analysis, endoscopic vein harvesting was not found to be a risk factor for vein graft occlusion or disease. The significant predictors identified were congestive heart failure, graft to the diagonal artery territory, larger vein conduit size, and graft flow. The authors concluded that endoscopic vein harvesting reduces leg wound complications in comparison to open vein harvesting without compromising the six-month patency rate. The overall patency rate depends on target and vein-related variables as well as patient characteristics, rather than the method of vein harvesting. Bonde, et al, 31 undertook a study to determine if endoscopic vein harvest reduces the morbidity associated with traditional open vein harvest (ie, significantly impaired wound healing and postoperative pain) and improves patient satisfaction without compromise in outcomes. From September 2000 to November 2001, 108 saphenous vein harvests were prospectively randomly assigned to EVH (n = 52) or OVH (n = 56); the groups were well matched demographically. EVH was performed with an endoscopic vein harvesting system by a single surgeon. Endpoints included impaired wound healing, operative and harvest time, vein quality (including histology), outcome, and postoperative pain. Followup was conducted for as long as three years. The findings demonstrated that endoscopic vein harvest was quicker to perform if sufficient vein for two grafts was needed; the new procedure did not prolong the overall operative time. Wound healing was significantly impaired in the OVH group compared with the EVH group. Postoperative pain was less in the EVH group. Statistical analysis showed that age, diabetes, peripheral vascular disease, total operative time, type of procedure, length of incision, and number of vein grafts were predictive of impaired wound healing. Furthermore, an increased number of late interventions were needed in the OVH group for wound-related morbidity. The 30

authors concluded this data demonstrates that endoscopic vein harvest results in fewer cases of impaired wound healing, reduced postoperative pain, and it does not prolong the operative time significantly nor compromise the vein quality. Furthermore, it is quicker to perform if two grafts are needed, and it reduces the need for late interventions. In an earlier study, Bitondo, et al, 32 developed a prospective, nonrandomized study to compare the outcomes of open versus endoscopic vein harvesting procedures in regards to wound complications. The authors studied 106 patients in an open vein harvesting group and 154 patients in an endoscopic vein harvesting group; patient characteristics and demographics were similar in both groups. The wound complications identified were dehiscence, drainage for greater than two weeks postoperatively, cellulitis, hematoma, and seroma/lymphocele. Wound complications were significantly less in the endoscopic vein harvesting group (9 of 133, 6.8%) versus the open vein harvesting group (26 of 92, 28.3%). After statistical analysis, the open vein harvest technique was found to be the only risk factor for postoperative leg wound complication. The authors concluded that endoscopic vein harvesting offered improved patient outcomes in terms of wound healing when compared to the open vein harvesting technique. ENDOSCOPIC VEIN HARVESTING: THE FUTURE IS NOW Just as minimally invasive endoscopic surgery has revolutionized many other surgical specialties, the endoscopic techniques that have been developed for saphenous vein harvesting are also transforming this specialty. However, because CABG is one of the most commonly performed surgical procedures in the US today, any modification in surgical technique has considerable implications for health care facilities, as well as the US health care system itself. One of these implications is reimbursement from the Centers for Medicare and Medicaid Services (CMS). 33 In July, 2008, CMS announced new Medicare and Medicaid payment and coverage policies to promote higher quality, more efficient care in order to improve the safety of hospitalized patients. The 2009 Inpatient Prospective Payment System (IPPS) final rule expanded the list of selected hospital-acquired conditions (HACs) that have Medicare payment implications beginning October 1, 2008. The HACs selected by CMS address several of the events on the National Quality Forum s (NQF s) list of Serious Reportable Adverse Events, commonly referred to as never events. 34 These events were selected according to the following criteria: Unambiguous; Usually preventable; Serious; Indicative of a safety system problem; and Important for public accountability. Specifically, if a condition is not present upon admission, but is subsequently acquired during the course of the patient s hospital stay, Medicare no longer pays the additional costs of the hospitalization; moreover, the patient is not responsible for the additional costs and cannot be billed. Included in this list is patient death or serious disability 31

associated with intravascular air embolism that occurs while being cared for in a health care facility. High-risk procedures (other than neurosurgical procedures that are known to present a high risk of intravascular air embolism) that include a small but known risk of air embolism are reportable under this event. Another HAC identified by the CMS is foreign object retained after surgery. The NQF defines unintended retention of a foreign object in a patient after surgery or other procedure as occurrences of the unintended retention of objects at any point after the surgery ends, regardless of the setting or whether the object is removed. Today, EVH has become the procedure of choice in harvesting saphenous veins for CABG procedures; approximately 80% of cardiac surgery centers offer EVH as a modality for saphenous vein harvesting. 35 Randomized trials have shown the benefits of veins harvested with this less invasive modality, including a lower infection rate, fewer wound complications, improved cosmesis, and greater patient satisfaction. While histological studies have revealed no significant difference with the endothelial integrity of the graft obtained with the EVH technique, EVH has been associated with residual intraluminal clot strands. 36,37,38,39 The perioperative considerations of an EVH technique that maximizes the benefits of this minimally invasive approach while addressing its potential risks and limitations have been described. SUMMARY Since its introduction decades ago, CABG surgery has dramatically changed the management of patients with ischemic heart disease. The saphenous vein, used in the majority of all coronary artery bypass procedures, remains an important conduit. The quality of the conduit is one factor that significantly influences the overall success of the CABG procedures. Because the success of CABG procedures is dependent on the long-term patency of the graft, poor conduit quality can result in perioperative failures. The traditional, open vein harvesting technique has generally remained unchanged despite the morbidity associated with this procedure, including wound complications, postoperative incisional pain, and prolonged recovery time. As with other surgical specialties, minimally invasive surgical techniques have been developed to improve outcomes in this patient population. EVH enables clinicians to obtain a high-quality saphenous vein conduit, while minimizing the complications associated with OVH. Specifically, technological advancements in the development of new technology that uses a non-occlusive trocar; an open insufflation system; and a unique locking, cutting, and sealing mechanism, provides a quality conduit by protecting the vessel during harvesting, and reducing the risk of intraluminal clot formation; this technology also improves patient safety by minimizing the risks for CO 2 embolism. Because of its numerous clinical advantages, EVH has become the standard of care for saphenous vein harvesting. Therefore, it is imperative that cardiologists, cardiac surgeons, and physician assistants involved in the care of CABG patients remain aware of the clinical considerations of EVH techniques. Through this awareness, as well as enhancement of technical skill and expertise, cardiologists, cardiac surgeons, and physician assistants can improve the quality of the conduits used in CABG procedures, thereby promoting positive surgical outcomes for their patients. 32

GLOSSARY Conduit A channel for the passage of fluids. Endoscopic Vein Harvesting (EVH) A minimally invasive technique for saphenous vein harvesting, using one small incision and one or two stab wounds. Greater Saphenous Vein The longest vein in the body, extending from the dorsum of the foot to just below the inguinal ligament, where it opens into the femoral vein. Hospital-Acquired Condition (HAC) A condition acquired by patients during hospitalization, with confirmation of diagnosis by clinical or laboratory evidence. HACs may not become apparent until the patient has been discharged from the hospital. Never Event Preventable medical errors that result in serious consequences for the patient. Open Vein Harvesting (OVH) The traditional approach to saphenous vein harvesting involving a longitudinal incision along the lower extremity. Patency The state of a bodily passage, duct, vessel, etc., of being open or unobstructed. Thrombogenicity The tendency of a material in contact with the blood to form a clot. Transesophageal Echocardiography (TEE) A method to perform an echocardiogram in which a specialized probe containing an ultrasound transducer at its tip is passed into the patient s esophagus, allowing the image and Doppler evaluation to be recorded. 33

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