Saphenous Vein Conduits Harvested by Endoscopic Technique Exhibit Structural and Functional Damage

Association between endoscopic vs open vein-graft harvesting and mortality, wound complications, and cardiovascular events in patients undergoing CABG surgery

CONTEXT

The safety and durability of endoscopic vein graft harvest in coronary artery bypass graft (CABG) surgery has recently been called into question.

OBJECTIVE

To compare the long-term outcomes of endoscopic vs open vein-graft harvesting for Medicare patients undergoing CABG surgery in the United States.

DESIGN, SETTING, AND PATIENTS

An observational study of 235,394 Medicare patients undergoing isolated CABG surgery between 2003 and 2008 at 934 surgical centers participating in the Society of Thoracic Surgeons (STS) national database. The STS records were linked to Medicare files to allow longitudinal assessment (median 3-year follow-up) through December 31, 2008.

MAIN OUTCOME MEASURES

All-cause mortality. Secondary outcome measures included wound complications and the composite of death, myocardial infarction, and revascularization.

RESULTS

Based on Medicare Part B coding, 52% of patients received endoscopic vein-graft harvesting during CABG surgery. After propensity score adjustment for clinical characteristics, there were no significant differences between long-term mortality rates (13.2% [12,429 events] vs 13.4% [13,096 events]) and the composite of death, myocardial infarction, and revascularization (19.5% [18,419 events] vs 19.7% [19,232 events]). Time-to-event analysis for those patients receiving endoscopic vs open vein-graft harvesting revealed adjusted hazard ratios [HRs] of 1.00 (95% CI, 0.97-1.04) for mortality and 1.00 (95% CI, 0.98-1.05) for the composite outcome. Endoscopic vein-graft harvesting was associated with lower harvest site wound complications relative to open vein-graft harvesting (3.0% [3654/122,899 events] vs 3.6% [4047/112,495 events]; adjusted HR, 0.83; 95% CI, 0.77-0.89; P < .001).

CONCLUSION

Among patients undergoing CABG surgery, the use of endoscopic vein-graft harvesting compared with open vein-graft harvesting was not associated with increased mortality.

Intimal thickness associated with endothelial dysfunction in human vein grafts

BACKGROUND

Intimal hyperplasia is a complex process thought to be initiated by injury and is the leading cause of vein graft failure. In the present investigation, we hypothesized that the basal intimal thickness in the human saphenous vein is a predictor of endothelial dysfunction and, potentially, intimal hyperplasia.

METHODS

Human saphenous veins were obtained during coronary artery bypass surgery. The segments were contracted with phenylephrine and relaxed with carbachol to determine the endothelial-dependent relaxation. The vein segments were fixed in 10% buffered formalin and grown for 14 d in high-serum culture and then fixed in formalin. The fixed tissues were stained with Verhoeff-Van Gieson, and the average intimal and medial thicknesses were calculated using light microscopy and a computerized image analysis system.

RESULTS

The human saphenous veins displayed varying amounts of basal intimal thickness (range 18.80-241.3 μm). The endothelial-dependent relaxation of the veins was highly variable, with values ranging from 0% to 27.59%. Human saphenous veins with a basal intimal thickness greater than 120 μm had significantly less endothelial-dependent relaxation (8.90% ± 6.32%) than those with a basal intimal thickness less than 120 μm (21.97% ± 10.64%). Endothelial dysfunction correlated with a basal intimal thickness greater than 120 μm (P = 0.02). The basal intimal thickness also correlated with increased intimal thickness after 14 d in organ culture (P = 0.0001).

CONCLUSIONS

A basal intimal thickness greater than 120 μm is a predictor of endothelial dysfunction. Also, because a greater basal intimal thickness correlated with an increased intimal thickness after organ culture, the basal intimal thickness might predict vein graft failure owing to intimal hyperplasia.

Is endoscopic harvesting bad for saphenous vein graft patency in coronary surgery?

PURPOSE OF REVIEW

Endoscopic vein harvest (EVH) has quickly been adopted as the standard-of-care for coronary artery bypass grafting (CABG). Despite clear advantages in terms of wound morbidity, healing, pain, and patient satisfaction, data from recent large clinical trials have called the safety of this technique into question.

RECENT FINDINGS

Post-hoc analyses of a variety of prospective trials have suggested EVH is associated with decreased graft patency, higher rates of cardiovascular complications (e.g. myocardial infarction, need for repeat revascularization) and mortality. Imaging studies of veins procured by EVH have revealed retained clot and vascular injury, particularly during the 'learning curve' of the technician. These findings may alter the quality of the conduit and, therefore, the outcome of the bypass graft. Elucidating the mechanisms that underlie any differences in results produced by the open and endoscopic procedures would help better inform clinical practice and the development of targeted strategies to improve EVH.

SUMMARY

Clear clinical advantages over traditional open vein harvest have allowed EVH to rapidly become the standard-of-care for harvesting of one or more vein grafts during CABG. The quality of these conduits, suggested to be equivalent by early studies, has come into question as groups with varying levels of experience have adopted the endoscopic technique. Elucidating the principles of 'best practice' for vein harvest will likely help shorten the learning curve and improve the safety of EVH.

Initial Experience with Endoscopic Saphenous Vein Harvesting for Coronary Artery Bypass Graft ing in Chinese Patients

<p><b>Objective:</b> We aimed to investigate the initial experience of endoscopic vein harvesting (EVH) for coronary artery bypass grafting (CABG) in Chinese patients.</p><p><b>Methods:</b> Forty patients scheduled for isolated CABG were prospectively randomized into an EVH group (n = 20) and an open vein harvesting (OVH) group (n = 20). Clinical data were collected, and all of the vein grafts were assessed by macroscopic appearance, histologic quality (endothelial integrity), and functional characteristics of endothelial nitric oxide synthase.</p><p><b>Results:</b> The 2 groups were similar with respect to hospital mortality (EVH group, 0; OVH group, 1; <i>P</i> = 1). There were no postoperative myocardial infarctions in either group and no deaths or reinterventions in either group during the follow-up period. Harvesting times in the 2 groups were similar (EVH, 12.15 � 2.32 min; OVH, 12.55 � 2.11 min; <i>P</i> = .571). Three patients in the EVH group were converted to a partly open or skin-bridge technique. Electrocautery at least 2 mm distal to the origin of the side branch was the safety margin.</p><p><b>Conclusions:</b> The use of EVH in Chinese patients was not related to adverse events and may be safely used for CABG procedures. Preoperative duplex mapping, systemic heparinization before harvesting, minimal surgical manipulation, and sectioning of side branches at least 2 mm distal to the origin may help improve the quality of vein grafts harvested with EVH and maximize the benefit of this less-invasive technique.</p>

Satisfaction with conduit harvest site scars in coronary bypass surgery

INTRODUCTION

Scars from conduit harvesting are common in coronary artery bypass patients. As an outward manifestation of surgery, the scar is important in patient perception of operative success and quality of care received. The aim of this study was to determine patient satisfaction with scars from radial artery and saphenous vein harvests at a tertiary cardiothoracic centre.

METHODS

We surveyed 62 patients attending follow-up appointment using the Patient Scar Assessment Questionnaire. This is a reliable and valid measure of a patient's perception of scarring. Data were analysed using ratings of scar attributes and features. We compared findings according to site and patient choice of scar site using the Mann-Whitney U test.

RESULTS

Analysis of both global and summative ratings showed no overall statistical differences between arm and leg scars (p<0.05). However, patients given a choice gave significantly higher ratings of scar appearance on global ratings versus those given no choice. Patients also reported greater satisfaction with appearance than those given no choice on summative ratings (p<0.05).

CONCLUSIONS

Patient choice of conduit site is an important determinant of the overall rating of scar appearance. Overall satisfaction is influenced by scar appearance. Clinicians should ensure, wherever possible, that they involve patients in conduit site selection.

Surgical Skin Markers Impair Human Saphenous Vein Graft Smooth Muscle and Endothelial Function

Marking human saphenous vein graft (HSV) with a surgical skin marker to prevent twisting on implantation is a common practice in peripheral and coronary artery bypass procedures. This study is designed to examine the effects of surgical skin markers on the HSV smooth muscle and endothelial functional responses. De-identified HSV remnants were collected during peripheral and coronary artery bypass procedures. Physiologic responses of the HSV were measured using a muscle bath. Veins that were marked with surgical skin markers intraoperatively generated significantly less contractile force to depolarizing KC1 (110 mM) and receptor-mediated contractile agonists than unmarked HSV, suggesting that surgical skin markers impaired HSV smooth muscle contractility. To directly access the effects of chemical components in the surgical skin markers, unmarked HSV was exposed to isopropyl alcohol (a solvent commonly used in surgical skin markers) or methylene blue (a dye). Smooth muscle contractility was significantly reduced by isopropyl alcohol and methylene blue. Endothelial-dependent relaxation to carbachol was significantly reduced after exposure to surgical skin markers. Our data demonstrated that marking HSV with surgical skin markers reduces smooth muscle and endothelial functional viability.

Evaluation of endoscopic vein extraction on structural and functional viability of saphenous vein endothelium

Objectives

Endothelial injury during harvest influences graft patency post CABG. We have previously shown that endoscopic harvest causes structural and functional damage to the saphenous vein (SV) endothelium. However, causes of such injury may depend on the extraction technique. In order to assess this supposition, we evaluated the effect of VirtuoSaph endoscopic SV harvesting technique (VsEVH) on structural and functional viability of SV endothelium using multiphoton imaging, biochemical and immunofluorescence assays.

Methods

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. A two cm segment from each portion was immersed in GALA conduit preservation solution and transported overnight to our lab for processing. 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).

Results

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 the VsEVH group.

Conclusions

This study indicates that VirtuoSaph endoscopic SV harvesting technique preserves the structural and functional viability of SV endothelium, but may differentially attenuate the vasomotor function of the saphenous vein graft.

Ultramini-Abstract

Endoscopic extraction preserved the structure and function, but attenuated the calcium mobilization and nitric oxide generation in human SV endothelium.

Endoscopic vein harvesting for coronary bypass grafting: a blessing or a trojan horse?

Conventional open harvest of the great saphenous vein (GSV) during CABG results in approximately 7% donor-site complications. Using endoscopic vein harvesting (EVH) the full GSV length can be harvested through a 3 cm incision. This nonsystematic review discusses several key issues concerning EVH, based on an extensive Pubmed search. Found studies show that EVH results in reduced number of wound complications, less postoperative pain, earlier postoperative mobilisation, reduced length of hospital stay, and is more cost-effective. Initial studies did not find significant differences in graft histology, patency, or clinical outcome. However, in 2009 convincing evidence of inferior histological graft properties became available. Furthermore, an observational study showed that EVH resulted in significantly more graft stenosis, was associated with higher mortality, more myocard infarction, and more reinterventions. Most recent publications could not confirm these findings, however larger randomised controlled trials focusing on graft quality are being awaited.

Impact of endoscopic versus open saphenous vein harvest technique on late coronary artery bypass grafting patient outcomes in the ROOBY (Randomized On/Off Bypass) Trial

OBJECTIVE

In the Randomized On/Off Bypass (ROOBY) Trial, the efficacy of on-pump versus off-pump coronary artery bypass grafting was evaluated. This ROOBY Trial planned subanalysis compared the effects on postbypass patient clinical outcomes and graft patency of endoscopic vein harvesting and open vein harvesting.

METHODS

From April 2003 to April 2007, the technique used for saphenous vein graft harvesting was recorded in 1471 cases. Of these, 894 patients (341 endoscopic harvest and 553 open harvest) also underwent coronary angiography 1 year after coronary artery bypass grafting. Univariate and multivariable analyses were used to compare patient outcomes in the endoscopic and open groups.

RESULTS

Preoperative patient characteristics were statistically similar between the endoscopic and open groups. Endoscopic vein harvest was used in 38% of the cases. There were no significant differences in both short-term and 1-year composite outcomes between the endoscopic and open groups. For patients with 1-year catheterization follow-up (n=894), the saphenous vein graft patency rate for the endoscopic group was lower than that in the open harvest group (74.5% vs 85.2%, P<.0001), and the repeat revascularization rate was significantly higher (6.7% vs 3.4%, P<.05). Multivariable regression documented no interaction effect between endoscopic approach and off-pump treatment.

CONCLUSIONS

In the ROOBY Trial, endoscopic vein harvest was associated with lower 1-year saphenous vein graft patency and higher 1-year revascularization rates, independent of the use of off-pump or on-pump cardiac surgical approach.

Pretreatment with intraluminal rapamycin nanoparticle perfusion inhibits neointimal hyperplasia in a rabbit vein graft model

PURPOSE

Poly lactic-co-glycolic acid nanoparticles (PLGA-NP) are widely used as a biodegradable biomaterial in medicine. Rapamycin-eluting stents have been used for prevention of restenosis during surgery. This study investigated the effect of pretreatment with intraluminal perfusion of carbopol-encapsulated rapamycin-loaded PLGA nanoparticles (RAP-PLGA-NP) on neointimal hyperplasia in a rabbit vein graft model.

METHODS

A segment of common carotid artery was replaced with a segment of external jugular vein in 60 rabbits which were then separated into four treatment groups, ie, Group 1, in which vein grafts were pretreated with intraluminal RAP-PLGA-NP perfusion, Group 2 in which vein grafts underwent equivalent empty vehicle (PLGA-NP) perfusion, Group 3, in which vein grafts received no treatment, and Group 4, which served as a sham operation group receiving normal vein contrast. On postoperative day 28, the grafts and normal veins were harvested for histologic examination, flow cytometry analysis, and high-performance liquid chromatography measurement.

RESULTS

Compared with Group 1, the intima of the grafts were thickened, the ratio of intimal area to vessel area increased, and the collagen volume index of the vein grafts increased significantly in Groups 2 and 3. The cell proliferation index in Group 1 (21.11 ± 3.15%) was much lower than that in Group 2 (30.35 ± 2.69%) and in Group 3 (33.86 ± 8.72%). By high-performance liquid chromatography measurement, retention of rapamycin was detected in Group 1 (11.2 ± 0.37 μg/10 mg) 28 days after single drug perfusion.

CONCLUSION

Pretreatment with intraluminal RAP-PLGA-NP perfusion may inhibit neointimal hyperplasia in vein grafts by penetrating into local tissue and limiting cell proliferation.

Mid-term outcomes for Endoscopic versus Open Vein Harvest: a case control study

Background

Saphenous vein remains the most common conduit for coronary artery bypass grafting with increasing uptake of minimally invasive harvesting techniques. While Endoscopic Vein Harvest (EVH) has been demonstrated to improve early morbidity compared to Open Vein Harvest (OVH), recent literature suggests that this may be at the expense of graft patency at one year and survival at three years.

Methods

We undertook a retrospective single-centre, single-surgeon, case-control study of EVH (n = 89) and OVH (n = 182). The primary endpoint was death with secondary endpoints including acute coronary syndrome, revascularisation or other major adverse cardiac events. Freedom from angina, wound complications and self-rated health status were also assessed. Where repeat angiography had been performed, this was reviewed.

Results

Both groups were well matched demographically and for peri-operative characteristics. All cause mortality was 2/89 (2%) and 11/182 (6%) in the EVH and OVH groups respectively. This was shown by Cox Log-Rank analysis to be non-significant (p = 0.65), even if adjusting for inpatient mortality (p = 0.74). There was no difference in the rates of freedom from angina (p = 1.00), re-admission (p = 0.78) or need for further anti-anginals (p = 1.00). There was a significant reduction in the incidence of leg wound infections and complications in the endoscopic group (EVH: 7%; OVH: 28%; p = 0.0008) and the skew of high patient self-rated health scores in the EVH group (61% compared to 52% in the open group) approached statistical significance (p = 0.06).

Conclusions

While aware of the limitations of this small retrospective study, we are heartened by the preliminary results and consider our data to be justification for continuing to provide patients the opportunity to have minimally invasive conduit harvest in our centre. More robust evidence is still required to elucidate the implications of endoscopic techniques on conduit patency and patient outcome, but until the results of a large, prospective and randomised trial are available, we believe we can confidently offer our patients the option and benefits of EVH.

Staples versus sutures for closing leg wounds after vein graft harvesting for coronary artery bypass surgery

BACKGROUND

Surgical site infection (SSI) after saphenous vein graft harvesting is a complication occurring in up to 18% of patients who undergo coronary artery bypass surgery (CABG). It is not known whether the method of skin closure influences the infection rate.

OBJECTIVES

To compare the rates of SSI and wound dehiscence of staples and sutures for skin closure after saphenous vein graft harvesting for CABG.

SEARCH STRATEGY

We searched the following electronic databases: The Cochrane Wounds Group Specialised Register (searched 11/3/10); The Cochrane Central Register of Controlled Trials (CENTRAL) - The Cochrane Library 2010 Issue 1; Ovid MEDLINE - 1950 to March Week 1 2010; Ovid MEDLINE - In-Process & Other Non-Indexed Citations (Searched 11/3/10); Ovid EMBASE - 1980 to 2010 Week 09 and EBSCO CINAHL - 1982 to March 11 2010. No date or language restrictions were applied.

SELECTION CRITERIA

Trials comparing staples and sutures for closing leg wounds after vein graft harvesting in patients undergoing CABG were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the titles and abstracts of references identified by the search strategy against the selection criteria and extracted data from eligible trials. Included trials were assessed for the following risks of bias: generation of random allocation sequence, allocation concealment, blinding, incomplete outcome data, selective reporting and freedom from other biases. For dichotomous variables, we calculated the relative risk with 95% confidence intervals (CI).

MAIN RESULTS

We included three prospective, randomised studies reporting on a total of 148 leg wounds closed with staples and 175 with sutures after vein graft harvesting in patients undergoing CABG. All trials were of sub-optimal methodological quality and all trials were at risk of bias. Leg wound infection rate was 10.8% (16/148) after leg wound closure with staples compared with 8% (14/174) with sutures (relative risk 1.20, 95% CI 0.60 to 2.39). Leg wound dehiscence occurred in 9.3% (10/108) of patients after leg wound closure with staples compared with 8.8% (12/137) with sutures (relative risk 1.05, 95%CI 0.43 to 2.53).

AUTHORS' CONCLUSIONS

These results suggest that there is no evidence of a difference in the risk of SSI and wound dehiscence when staples rather than sutures are used to close leg wounds after vein graft harvesting during CABG, however more research is needed.

The Graft Imaging to Improve Patency (GRIIP) clinical trial results

OBJECTIVE

This trial aimed to determine whether intraoperative graft assessment with criteria for graft revision would decrease the proportion of patients with 1 or more graft occlusions or stenoses or major adverse cardiac events 1 year after coronary artery bypass grafting.

METHODS

A single-center, randomized, single-blinded, controlled clinical trial was designed. Patients were randomized to either of 2 groups: intraoperative graft patency assessment using indocyanine-green fluorescent angiography and transit-time flowmetry, with graft revision according to a priori criteria (imaging group), or standard intraoperative management (control group). Patients underwent follow-up angiography at 1 year.

RESULTS

Between September 2005 and August 2008, 156 patients undergoing isolated coronary bypass grafting were enrolled (imaging, n = 78; control, n = 78). Demographic and angiographic characteristics were similar between groups. Operative, crossclamp, and cardiopulmonary bypass times were all nonsignificantly longer in the imaging arm. The number of grafts per patients was similar (imaging, 3.0 +/- 0.7; control, 3.0 +/- 0.7). The frequency of major adverse cardiac events (death, myocardial infarction, repeat revascularization) was not different between groups at 1 year postoperatively (imaging, 7.7%; control, 7.7%). One-year angiography was performed in 107 patients (imaging, 55 patients/160 grafts; control, 52 patients/152 grafts). The proportion of patients with 1 graft occlusion or more was comparable in the imaging (30.9%) and control (28.9%) groups (relative risk [95% confidence interval], 1.1 [0.6-1.9]; P = .82), as were other graft patency end points. The incidence of saphenous vein graft occlusion was high in both groups.

CONCLUSIONS

Routine intraoperative graft assessment is safe but does not lead to a marked reduction in graft occlusion 1-year after bypass grafting. The incidence of saphenous vein graft failure remains high despite contemporary practice and routine intraoperative graft surveillance.

Evaluation of blood components exposed to coated arterial filters in extracorporeal circuits

Background: Biocompatible surfaces play an important role in the inflammatory response during cardiopulmonary bypass (CBP), with the arterial filter contributing a large surface area of the circuit. Different filter-coating materials designed to improve blood-filter biocompatibility are currently used in CPB circuits. This study evaluates eight biocompatible coatings used for arterial filters and their effects on blood components during circulation. Methods: Arterial filters were randomly assigned in eight independent heparin-bonded tubing loops and perfused by a single swine (n=8). Arterial blood was routed simultaneously, but separately, into each circuit and circulated for 30 minutes at 37°C. Blood samples were drawn for CBC, ACT, and TAT III measurements at baseline, post-heparinization and post-circulation. At study completion, filters were imaged using multiphoton microscopy. Results: RBC, platelet, and WBC counts, and TAT III complex were all decreased after 30 minutes of circulation; however, WBC count was the only parameter that showed statistically significant differences between the filters. Circulating WBC reduction ranged from 6% (Carmeda and Trillium) to 41% (Terumo-X-coating) with corresponding microscopic confirmation of increased WBC entrapment. Conclusion: All eight filter coatings altered the blood components to varying degrees. Selection of the most effective filter, in conjunction with a heparin-bonded circuit for CPB, may decrease the intraoperative foreign-surface activation of blood cells.

Endoscopic versus open vein-graft harvesting in coronary-artery bypass surgery

BACKGROUND

Vein-graft harvesting with the use of endoscopy (endoscopic harvesting) is a technique that is widely used to reduce postoperative wound complications after coronary-artery bypass grafting (CABG), but the long-term effects on the rate of vein-graft failure and on clinical outcomes are unknown.

METHODS

We studied the outcomes in patients who underwent endoscopic harvesting (1753 patients) as compared with those who underwent graft harvesting under direct vision, termed open harvesting (1247 patients), in a secondary analysis of 3000 patients undergoing CABG. The method of graft harvesting was determined by the surgeon. Vein-graft failure was defined as stenosis of at least 75% of the diameter of the graft on angiography 12 to 18 months after surgery (data were available in an angiographic subgroup of 1817 patients and 4290 grafts). Clinical outcomes included death, myocardial infarction, and repeat revascularization. Generalized estimating equations were used to adjust for baseline covariates associated with vein-graft failure and to account for the potential correlation between grafts within a patient. Cox proportional-hazards modeling was used to assess long-term clinical outcomes.

RESULTS

The baseline characteristics were similar between patients who underwent endoscopic harvesting and those who underwent open harvesting. Patients who underwent endoscopic harvesting had higher rates of vein-graft failure at 12 to 18 months than patients who underwent open harvesting (46.7% vs. 38.0%, P<0.001). At 3 years, endoscopic harvesting was also associated with higher rates of death, myocardial infarction, or repeat revascularization (20.2% vs. 17.4%; adjusted hazard ratio, 1.22; 95% confidence interval [CI], 1.01 to 1.47; P=0.04), death or myocardial infarction (9.3% vs. 7.6%; adjusted hazard ratio, 1.38; 95% CI, 1.07 to 1.77; P=0.01), and death (7.4% vs. 5.8%; adjusted hazard ratio, 1.52; 95% CI, 1.13 to 2.04; P=0.005).

CONCLUSIONS

Endoscopic vein-graft harvesting is independently associated with vein-graft failure and adverse clinical outcomes. Randomized clinical trials are needed to further evaluate the safety and effectiveness of this harvesting technique.