Randomized trial of endoscopic versus open vein harvest for coronary artery bypass grafting: Six-month patency rates

Role of procurement-related injury in early saphenous vein graft failure after coronary artery bypass surgery

Saphenous vein graft thrombosis after coronary artery bypass graft surgery is a poorly understood problem that lessens the benefits of this procedure. Recent studies highlight the importance of injury sustained at the time of saphenous vein graft procurement in the pathogenesis of acute graft thrombosis. In particular, damage to the graft endothelium that occurs secondary to ex vivo pressure distention, a common practice during vein harvest, leads to a loss of antithrombotic factors and increased activity of subendothelial prothrombotic factors. The prothrombotic potential of damaged grafts is further exacerbated by an ischemic storage interval and subsequent exposure to arterial flow conditions after grafting. A clearer understanding of the mechanisms by which endothelial disruption leads to acute saphenous vein graft thrombosis may result in interventions for improving our procurement techniques, interrupting the downstream effects of the damaged saphenous vein graft and/or discriminating damage that is beyond an acceptable threshold of thrombotic risk.

Femoral-popliteal bypass with endoscopically harvested saphenous vein in patients with TASC D disease of the superficial femoral artery

BACKGROUND

This study evaluated patients undergoing femoropopliteal bypasses using endoscopically harvested vein to treat Trans-Atlantic Inter-Society Consensus (TASC) stage D lesions. Primary patency and primary assisted patency were evaluated, as were perioperative morbidity and mortality and hospital length of stay (LOS). Results for this minimally invasive alternative to femoropopliteal bypass with conventional open vein harvesting were analyzed.

METHODS

A retrospective analysis was performed on patients who underwent femoral-popliteal bypass with endoscopic saphenous vein harvest and angiographic TASC D anatomy. Postoperative duplex exams were evaluated, and the study end points of graft thrombosis or the development of a high-grade stenosis prompting reintervention were sought. Patient demographics, morbidity, mortality, and hospital LOS were analyzed.

RESULTS

Twenty-seven patients meeting our inclusion criteria underwent surgery between June 2002 and June 2007. Indications for surgery in these patients were claudication (n=10), gangrene or ulceration (n=9), and ischemic rest pain (n=8). Fifty-two percent of the patients were male, 50% had cardiac disease, 65% had hypertension, 54% were diabetic, and 65% had a significant smoking history. Median LOS was 2.5 days in claudicants, 3.0 days in patients with rest pain, and 7.0 days in patients with gangrene or ulceration (p<0.05). Kaplan-Meier primary patency and primary assisted patency rates were 73.2% and 80.8% at 1 year, respectively; and these rates were maintained for 70 months. The only perioperative complication was a superficial wound infection, and two patients died during follow-up from causes unrelated to the surgery.

CONCLUSION

Femoropopliteal bypass using endoscopic vein harvest is a durable reconstructive vascular procedure which can be performed with minimal postoperative morbidity, short LOS, and satisfactory long-term patency.

Haemodynamic effects during endoscopic vein harvest of the saphenous vein for off-pump coronary artery bypass grafting surgery

OBJECTIVE

Endoscopic vein harvest (EVH) for coronary artery bypass grafting surgery is performed with carbon dioxide (CO2) insufflation for visualization and dissection. The insufflated CO2 is rapidly absorbed into the body and may influence haemodynamics. However, the haemodynamic changes during EVH have not been clearly defined. This study evaluated the haemodynamic effects during EVH of the saphenous vein for off-pump coronary artery bypass grafting surgery (OPCAB).

METHODS

After fixing the position for harvesting of the left internal mammary artery, EVH of the saphenous vein was performed at a maximum CO2 pressure of 12 mmHg and a flow of 3 l/min. The haemodynamic parameters were measured before and just after the end of endoscopic vein harvest.

RESULTS

One hundred patients were studied. The end-tidal CO2 pressure (P(ET)CO2, 35.0 +/- 2.7 vs. 52.0 +/- 6.2 mmHg), partial pressure of arterial CO2 (PaCO2, 35.1 +/- 3.1 vs. 52.5 +/- 4.3 mmHg), mixed venous oxygen saturation (SvO2, 75.6 +/- 4.1 vs. 82.0 +/- 1.6%), cardiac index (2.7 +/- 0.6 vs. 3.3 +/- 0.6 l/min/m2), and cerebral oxygen saturation (ScO2, left: 63.5 +/- 7.9 vs. 73.3 +/- 8.4; right: 62.2 +/- 8.0 vs. 72.3 +/- 6.3%) differed significantly between before and after CO2 insufflation, whereas mean systemic blood pressure, mean pulmonary artery blood pressure, central venous pressure, heart rate, partial pressure of arterial oxygen, and peak inspiratory pressure did not differ significantly between before and after CO2 insufflation.

CONCLUSIONS

EVH, at a maximum CO2 pressure of 12 mmHg and a flow of 3 l/min, of the saphenous vein for OPCAB was associated with hypercarbia and a tolerable range of hypercarbia (PaCO2 < 60 mmHg) increased the cardiac index and ScO2 without any complications.

A prospective audit of endoscopic vein harvesting for coronary artery bypass surgery

INTRODUCTION

The objectives of this study were to: (i) assess the feasibility of minimally invasive endoscopic harvesting of the long saphenous vein or radial artery for use as conduit during coronary artery bypass surgery in the NHS setting; and (ii) investigate the results of endoscopic vein harvesting with regards to postoperative complications, ability to mobilise, and patient satisfaction.

PATIENTS AND METHODS

In this prospective audit, 25 consecutive patients, aged 52-90 years, undergoing either coronary artery bypass grafting alone or together with valve surgery or atrial fibrillation ablation were studied. All data were entered in purpose-designed proforma. Pre-operative risk factors including increasing age, diabetes, peripheral vascular disease, obesity, renal impairment, tobacco consumption and steroid use were documented. Time taken for harvest and conversion to traditional open vein harvest, quality of harvested vein in terms of number of repairs and vein damage were recorded. Postoperatively, we recorded harvest site wound complications, number of days to mobilise and total hospital stay. Pain score and patient satisfaction were also assessed.

RESULTS

There was one death due to myocardial infarction; another patient had postoperative cerebrovascular accident. A total of 43 lengths of grafts were harvested, 41 were long saphenous vein and two radial artery. Vein harvest time reduced significantly from a maximum of 94 min to 34 min for two lengths of long saphenous vein. Three patients required conversion from endoscopic vein harvesting to open vein harvest. The only postoperative complication directly related to endoscopic harvesting was bruising along the tunnel created by the passage of the instruments. None of the patients had any wound complication; none required antibiotics or wound debridement. Mean time to mobilise was 3.4 days. All patients who underwent successful endoscopic vein harvesting expressed satisfaction with regards to postoperative pain and cosmetic result.

CONCLUSIONS

Competence and ability to harvest conduit in an acceptable time frame are obtainable after a relatively low number of cases. The procedure is associated with a low number of postoperative complications and very high patient satisfaction.

Coronary vein graft disease: pathogenesis and prevention

Not long after coronary artery bypass grafting surgery was described, several reports presented follow-up angiographic data on large cohorts of patients, demonstrating that approximately one-half of saphenous vein grafts fail within 10 to 15 years of surgery and that graft failure is associated with worse clinical outcomes. Three processes are responsible for vein graft failure. Thrombosis, intimal hyperplasia and accelerated atherosclerosis contribute to graft failure in the acute, subacute and late postoperative periods, respectively. Studies have shown that perioperative antiplatelet therapy can reduce early thrombosis and graft failure. As in native coronaries, intensive lipid lowering can attenuate the process of atherosclerosis in vein grafts. Intimal hyperplasia in the vein graft is thought to be an adaptation of the vein to higher pressures in the arterial circulation. This process is further promoted by the loss of inhibition from the endothelial layer, which is injured during surgery. A new 'no-touch' technique for harvesting grafts may be effective in preventing disruption to the endothelial layer, and subsequent intimal hyperplasia and graft loss. Off-pump surgery and endoscopic vein harvesting, which are known to reduce surgical morbidity, have been shown to be no worse than on-pump surgery and open vein harvesting, respectively, in terms of vein graft patency. Various gene therapies can prevent intimal hyperplasia in animal models, but human data obtained so far have been disappointing. Placing an external stent around a vein graft may reduce tangential wall stress and subsequent intimal hyperplasia.

Leg Wound Infections Following Greater Saphenous Vein Harvesting: Minimally Invasive Vein Harvesting Versus Conventional Vein Harvesting

Wound complications associated with long incisions used to harvest the greater saphenous vein are common and well documented. We compared leg wound infection rates, wound healing disturbances (WHDs), length of vein harvested, vein harvest time, and total surgical time between minimally invasive saphenous vein harvesting (MIVH) and conventional vein harvesting (CVH) techniques. This meta-analysis showed a significant reduction in wound infections in favor of the MIVH group (odds ratio = 0.19; 95% confidence interval = 0.14-0.25) and a significant reduction in WHDs in favor of the MIVH group (odds ratio = 0.26; 95% confidence interval = 0.20-0.34). The MIVH and CVH techniques are equivalent with respect to saphenous vein harvest time, saphenous vein harvest length, and total surgical time. A visual inspection of “funnel” plots suggests a mild to moderate publication bias. This meta-analysis suggests that leg wound infections and wound healing disturbances are reduced using MIVH techniques.

[Endoscopic harvesting of saphenous vein during coronary artery bypass operations]

The great saphenous vein is the most commonly applied conduit in coronary bypass surgery during the treatment of ischaemic heart disease. Regarding the increasing age of patients, multiple comorbid factors and poor patient's general state, the minimally invasive approach is of basic significance during these operations.

OBJECTIVES

The aim of study was to evaluate the possibilities of endoscopic saphenous vein harvesting and the quality of saphenous veins harvested endoscopically.

METHODS

The authors applied the endoscopic approach for saphena harvesting in 24 patients undergoing coronary bypass surgery or combined bypass surgery with valve reconstruction. Ten of the harvested veins were sent for histologic examination to evaluate the structure of the endothelial layer.

RESULTS

No wound complications were noted with the endoscopic approach. The harvested veins were used as conduits during surgery except for 2 cases, where the calibre of the vein was too small to apply. The histologic examination revealed normal structure of the endothelial layer in all of the 10 cases.

CONCLUSION

The endoscopic approach can be used in the harvesting of saphenous vein during coronary bypass surgery. For the time being, the apply of this approach is restricted by the longer operation time, which hopefully would be reduced in the future.

Aspirin in coronary artery bypass surgery: new aspects of and alternatives for an old antithrombotic agent

The success of coronary artery bypass graft surgery (CABG) depends mainly on the patency of the graft vessels. Aortocoronary vein graft disease is comprised of three distinct but interrelated pathological processes: thrombosis, intimal hyperplasia and atherosclerosis. Early thrombosis is a major cause of vein graft attrition during the first month after CABG, while during the remainder of the first year, intimal hyperplasia forms a template for subsequent atherogenesis, which thereafter predominates. Platelets play a crucial role in the pathophysiology of graft thrombosis and aspirin is the primary antiplatelet drug that has been shown to improve vein graft patency within the first year after CABG. Nevertheless, a significant number of grafts still occlude in the early postoperative period despite 'appropriate' aspirin treatment. Moreover, laboratory investigations showed that the expected inhibition of platelet function is not always achieved. This has been called 'aspirin nonresponse' or 'aspirin resistance', although a uniform definition is lacking. The finding that a considerable number of patients show an impaired antiplatelet effect of aspirin after CABG brought new insight into the discussion concerning poor patency rates of bypass grafts: the early period after CABG shows a coincidence of an increased risk for bypass thrombosis (amongst others, due to platelet activation and endothelial cell disruption of the graft) and an increased prevalence of aspirin resistance. Hitherto, the underlying mechanisms of aspirin resistance are uncertain and largely hypothetical; amongst others, increased platelet turnover, enhanced platelet reactivity, systemic inflammation, and drug-drug interaction are discussed. Up to now available data concerning the clinical outcome of aspirin resistant CABG patients are limited, and there is evidence that platelets of patients with graft thrombosis are more likely to be resistant to aspirin compared with patients without thrombotic events. Many publications concerning aspirin resistance are available today, but reports addressing this topic in CABG patients are sparse. This review summarises recent insights into the antiplatelet treatment after CABG and describes the clinical benefit, but also the therapeutic failure of the well-established drug aspirin. Moreover, possible pharmacological approaches to improve antithrombotic therapy in aspirin nonresponders among CABG patients are discussed.

External carotid artery to middle cerebral artery bypass with the saphenous vein graft

Patients with occlusive cerebrovascular disease who have failed maximal medical therapy, which consists of antiplatelet agents as well as maximizing modifiable risk factors such as blood pressure, cholesterol, smoking cessation, and obesity, and whose lesions are not amenable or have not responded to the more common vascular procedures (i.e., carotid endarterectomy or stenting) are considered candidates for an extracranial-intracranial bypass. Additionally, for a patient to be a candidate, he/she must have an adequate graft vessel. Typically, this vessel is the superficial temporal artery. However, oftentimes, the superficial temporal artery is an inadequate vessel or the patient requires a high-flow conduit. It is in these patients that use of the saphenous vein should be considered. In this report, we detail the technical aspects of performing an extracranial-intracranial bypass by using a saphenous vein graft.

Endoscopic vs Conventional Vein Harvesting: A Prospective Analysis

Minimally invasive vein harvesting is associated with better leg wound healing and a lower incidence of wound infections. We analyzed our experience in 2 prospectively enrolled groups of non-randomized patients undergoing elective coronary artery bypass grafting. Group 1 was 81 patients who had endoscopic vein harvesting; group 2 was 80 who had conventional open vein harvesting. The time taken for endoscopic harvest (skin incision to skin closure) was significantly less than that for open harvest (51.07 vs 75.94 min). The number of cases to reach a plateau on the learning curve for endoscopic vein harvest was 20 for 2 lengths of vein and 35 for 3 lengths of vein. Significantly more suture repairs per vein were required in group 1 (1.32) than group 2 (0.38). The incidence of wound infection was 1.2% in group 1 vs 8.8% in group 2. Endoscopic vein harvesting is not difficult to learn and it should be preferred over open vein harvest, given its benefits in wound healing.

Endoscopic harvest of saphenous vein: a lesson learned from 1,348 cases

BACKGROUND

Endoscopic harvest of saphenous vein is a relatively new technique developed to minimize the wound and postoperative complications. This technique has gained patients' acceptance and become popular in cardiac surgical practices. Because most centers have limited experience with this approach, the authors summarize the clinical profiles of patients undergoing endoscopic vessel harvest (EVH).

METHODS

Between March 2001 and August 2006, 1,348 patients (945 men and 403 women) with a mean age of 67.2 years (range, 28-89 years) underwent EVH of saphenous vein for coronary artery bypass surgery, peripheral artery reconstruction, and miscellaneous conditions. The EVH technique was performed using the Vasoview system (Guidant, Menlo Park, CA, USA) under the assistance of carbon dioxide (CO(2)) insufflation.

RESULTS

Technical success was achieved in 98.6% of the cases. Two saphenous veins were discarded because of obvious vein injury. The mean harvest time was 45 min: 68 min for the first 50 cases and 23 min for the last 200 cases. Nearly all the patients (98%) had saphenous vein harvested only from the thighs, whereas only 1.5% of the patients had saphenous vein harvested from the legs. Postoperative wound complications were experienced by 61 patients including 25 tract hematomas, 19 wound dehiscences or poor healing, 16 wound infections, and 1 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 for 169 patients.

CONCLUSION

The findings showed EVH of saphenous vein to be a valid alternative to open saphenectomy, providing excellent surgical results. Therefore, EVH should be considered as the standard of care for saphenous vein harvest.

Cardiac Surgery in Patients With Body Mass Index of 50 or Greater

BACKGROUND

The seemingly inexorable rise in obesity worldwide is creating a new set of challenges for healthcare providers. Demand for cardiac surgical intervention among patients at extreme levels of obesity (body mass index [BMI] > or = 50) is increasing; however, the risks, benefits, and resources required to meet this need have not been established.

METHODS

Between 1993 and 2004, 57 patients with a BMI of 50 or more underwent cardiac surgical procedures at our institution. The mean BMI was 54 +/- 4, weight range was 124 to 226 kg. The mean age of the study group was 55 +/- 12 years, and comorbidities included diabetes mellitus in 29 (51%), hypertension in 40 (70%), hyperlipidemia in 22 (39%), and obstructive sleep apnea in 16 (28%).

RESULTS

The operative mortality was 7% (4 patients). Eleven patients (20%) required prolonged intubation (more than 24 hours), and mean intensive care unit stay was 5 +/- 9 days. Wound complications requiring surgery occurred in 3 (5%). Survival at 1 and 5 years was 93% +/- 4% and 76 +/- 8%, respectively. By univariate analysis, age and endocarditis were associated with long-term mortality and major perioperative complications. As a dichotomous variable, BMI greater than 54 was a significant predictor of renal failure and prolonged mechanical ventilation.

CONCLUSIONS

Cardiac surgery in the patient with a BMI of 50 or greater is associated with significant resource utilization, including prolonged intensive care unit and hospital stay, with prolonged intubation and wound complications relatively common.

Postoperative and mid-term wound disturbance outcomes of minimally invasive saphenous vein harvest using the VEGA system

Great saphenous vein harvest is associated with a significant risk of impaired wound healing. The purpose of this study was to determine efficacy of one system designed for minimally invasive vein harvest (MIVH) and to assess postoperative and mid-term wound-healing disturbances. From February 2004 to June 2005, great saphenous harvest for coronary artery bypass grafting (CABG) was performed in a group of 120 consecutive patients employing the VEGA system (B/Braun-Aesculap, Tuttlingen, Germany). Patients were evaluated on 7th postoperative day, at the 3-month and 1-year follow-up for wound healing disturbances, residual leg edema, and saphenous neuropathy. The mean age was 67.3 years, male patients dominated (70%), and the leading procedure was CABG (83%). The mean number of harvested venous grafts was 1.9 +/- 1.2 and the mean number of skin incisions was 3.7 +/- 2.2. The mean total vein harvesting time was 40.2 +/- 16.8 minutes. Satisfactory healing was achieved in 98% patients on 7th postoperative day and at the 3-month follow-up all wounds were completely healed. Saphenous neuralgia remained a significant cause of morbidity, although its incidence decreased from 25% presented on 7th postoperative day to 8% presented at 1-year follow-up. Likewise, the incidence of leg edema decreased from 34% on the 7th postoperative day to 7% at 1-year follow-up. Minimally invasive vein harvest is a safe method associated with a significant reduction of wound disturbances. The VEGA system appears to be suitable and effective equipment for MIVH. Nevertheless, residual edema and mainly saphenous neuropathy represent a relatively frequent cause of patient morbidity at the postoperative and mid-term follow-up.

Technical modifications in endoscopic vein harvest techniques facilitate their use in lower extremity limb salvage procedures

OBJECTIVE

We describe and report our results using endoscopic vein harvest (EVH) for lower extremity arterial bypass procedures, following the implementation of technical modifications specific to patients undergoing limb salvage procedures.

METHODS

We underwent training in EVH, followed by implementation of the technique in patients requiring limb salvage for lower extremity ischemia and aneurysms. After technical modifications in the technique were developed for limb salvage, we reviewed our experience in all patients who underwent minimally invasive distal bypass with EVH.

RESULTS

Technical modifications include limited arterial dissection before vein harvest, the use of proximal and distal leg incisions for both exposure of arterial vessels and saphenous vein harvest, improved hemostasis techniques in the vein graft tunnel, avoidance of compression wraps to the ipsilateral harvest tunnel, complete removal of the vein with either reversed or nonreversed graft placement, and use of the endoscopic tunnel for conduit placement. Thirteen patients (14 limbs) have undergone minimally invasive distal bypass since technical modifications were implemented. Indications for EVH were rest pain (n = 12; 85.7%) and tissue loss (n = 8; 57.1%). Veins harvested were the ipsilateral great saphenous vein (n = 10; 71.4%), contralateral great saphenous vein (n = 2; 14.3%), and short saphenous vein (n = 2; 14.3%). No venous injuries occurred during endoscopic harvest, and all were used for bypass. Thirty-day primary and primary assisted patency rates were 85.7% and 92.9%, respectively. The limb salvage rate was 100%. Two patients developed postoperative hematomas, one early and one late, as a result of anticoagulation for cardiac comorbidities. Both patients required reoperation for successful re-establishment of patency. There were no perioperative deaths and no postoperative wound infections or complications. Two patients required a later prosthetic bypass, and two required a vein graft angioplasty. Complete wound healing was achieved in 75% of patients with preoperative tissue loss.

CONCLUSIONS

Technical modifications in endoscopic saphenous vein harvest techniques facilitate their use in lower extremity limb salvage procedures. Vascular surgeons should become familiar with these techniques to minimize vein harvest wound complications and extend the options for limb salvage conduits, including use of both the ipsilateral and contralateral saphenous vein and the short saphenous vein. Meticulous hemostasis within the tunnel after endoscopic conduit harvest and avoidance of postoperative anticoagulation should help to prevent postoperative hematoma formation and early graft occlusion.

Catheter-based infrared light scanner as a tool to assess conduit quality in coronary artery bypass surgery

OBJECTIVES

Endothelial disruption within saphenous vein and radial artery grafts increases thrombosis risk. However, no clinically applicable method for imaging the intima currently exists. We used a novel infrared imaging technology, optical coherence tomography (OCT; LightLab Imaging, Inc, Westford, Mass), to visualize the intima within harvested conduits.

METHODS

Conduits were procured endoscopically (37 saphenous vein grafts and 8 radial artery grafts) or with the open technique (9 radial artery grafts) from 50 patients. Surplus segments were analyzed by means of OCT for evidence of preexisting pathology or traumatic injury. Focal plaques in radial artery grafts and the intimal hyperplasia area in saphenous vein grafts were quantified as having an intimal/medial thickness ratio of greater than 0.5. Biopsy specimens were obtained for histologic confirmation and to analyze matrix metalloproteinase 2 levels (saphenous vein grafts) and prostacyclin/nitric oxide metabolites (radial artery grafts). Interobserver kappa coefficients and a Bland-Altman analysis were used to determine the reproducibility and accuracy of OCT interpretations.

RESULTS

Radial artery imaging revealed plaque in 76%. Endoscopically harvested vessels showed intraluminal clot (38%) and intimal tears ranging from severe (6%) to mild (88%). In saphenous vein grafts intimal thickening was detected in 86% and intraluminal clotting in 68%. The intimal/medial thickness ratio determined by means of OCT correlated directly with matrix metalloproteinase 2 levels (R = 0.6804) in saphenous vein grafts and inversely with metabolites of prostacyclin (R = -0.55) and nitric oxide (R = -0.58) in radial artery grafts. OCT imaging was reproducible (interobserver kappa coefficients of >0.81 for the characterization of plaque types) and showed a strong correlation with histology (R = 0.8, P < .001).

CONCLUSIONS

OCT imaging provides an accurate, real-time, and reproducible means for assessing saphenous vein graft and radial artery graft bypass conduits. As a quality assurance tool, this technology might afford a more objective basis for conduit selection.

Influence of tangential stress on mechanical responses to vasoactive agents in human saphenous vein with and without perivascular adipose tissue

AIM

Improvement in short-term patency of vein grafts harvested with the surrounding tissue and no distention has been noted. The influence of transient tangential stress on mechanical function to vasoactive agents in isolated human saphenous veins stripped or with attached perivascular adipose tissue was assessed.

METHODS

Concentration-response curves to noradrenaline, 5-hydroxytryptamine, methylcholine, sodium nitroprusside and nicardipine were constructed for veins exposed to no, low (approximately 120 mmHg) or high (approximately 240 mmHg) tangential stress.

RESULTS

Tangential stress did not affect contractile effects of noradrenaline or relaxant effects of methylcholine and sodium nitroprusside. Regression analysis of the concentration-response curve to 5-hydroxytryptamine revealed a significant (P=0.042) increase in sensitivity in saphenous veins without perivascular adipose tissue exposed to no tangential stress, compared with veins with attached adipose tissue. Exposure to high stress significantly (P=0.024) increased the potency of 5-hydroxytryptamine in blood vessels without perivascular adipose tissue, as opposed to veins with adipose tissue. Relaxant responses to nicardipine in veins with perivascular adipose tissue were significantly (P=0.001) affected by exposure to low tangential stress compared with no or high tangential stress. A parallel comparison revealed that intact veins compared with those without perivascular adipose tissue exposed to low stress were significantly (P=0.020) more resistant to the relaxant effects of nicardipine.

CONCLUSION

The findings of the present report support the view that tangential stress has an impact on the actions of vasoactive agents, but this influence is variable and factor(s) released from perivascular adipose tissue may have a bearing on the observed effect.

Manual pressure distension of the human saphenous vein changes its biomechanical properties—implication for coronary artery bypass grafting

Patency rates of saphenous vein grafts following coronary artery bypass grafting (CABG) depend on multiple factors. Information regarding the impact of biomechanical properties of vein grafts on patency rates is not available. The objective of the present study was to evaluate whether uncontrolled manual pressure distension during routine preparation of the saphenous vein in CABG-induced changes in the biomechanical properties of the vein. The morphometric and stress-strain properties were studied in isolated segments of the saphenous vein from 12 patients undergoing elective CABG. Six segments were manually distended without pressure control and six were not distended. The mechanical test was performed as a ramp inflation using syringe pump. The vein dimensions were obtained from digitised images at different pressures as well as at the no-load and zero-stress states. The circumferences, the wall and lumen area, the wall thickness, and the outer diameter as function of the applied pressure were largest in the segments with uncontrolled manual distension compared to those without distension (P<0.05). The opening angle and the absolute value of the residual strains were lower (P<0.01) and the circumferential stress-strain curve shifted to the left, indicating the wall became stiffer with uncontrolled manual distension compared to those without distension (P<0.05). In conclusion, manual pressure distension changed the morphometric and biomechanical properties of the saphenous vein. The perspective is that studies on biomechanical properties on the saphenous vein may guide surgeons how to handle graft material without causing major changes of the biomechanical properties during harvesting and preparation.

Harvesting the saphenous vein with surrounding tissue for CABG provides long-term graft patency comparable to the left internal thoracic artery: results of a randomized longitudinal trial

OBJECTIVE

Conventional harvesting of the saphenous vein in coronary artery bypass surgery produces vessel damage that contributes to graft failure. A novel "no touch" technique provides high short- and long-term patency rates.

METHOD

This randomized longitudinal trial compares graft patency of two patient groups undergoing coronary artery bypass surgery. Conventional: 52 patients had their veins stripped, distended, and stored in saline solution. No-touch: 52 patients had veins removed with surrounding tissue, not distended, and stored in heparinized blood. Angiographic assessment was performed at mean time 18 months after the operation in 46 patients in the conventional group and 45 patients in the no-touch group and repeated at mean time 8.5 years in 37 patients from both groups.

RESULTS

The distribution of the grafts to the recipient coronary arteries regarding their size and quality was similar in both groups. The angiographic assessment at 18 months postoperatively showed 89% conventional versus 95% no-touch grafts were patent. Repeated angiography at 8.5 years showed a patency rate for the conventional group of 76% and 90% for the no-touch group (P = .01). The multivariate analysis showed that the most important surgical factors for graft patency were the technique of harvesting (odds ratio= 3.7, P = .007) for the no-touch versus the conventional technique and the vein quality before implantation (odds ratio = 3.2, P = .007) for veins that were of good quality. By comparison the patency of the thoracic artery grafts was 90%.

CONCLUSION

Harvesting the saphenous vein with surrounding tissue provides high short- and long-term patency rates comparable to the left internal thoracic artery.

Reduction of carbon dioxide embolism for endoscopic saphenous vein harvesting

BACKGROUND

The endoscopic saphenous vein harvesting (EVH) introduced in coronary artery bypass surgery (CABG) is associated with less wound complication and postoperative pain. Carbon dioxide (CO2) insufflation is used during EVH to facilitate the procedure. The purpose of this study was to determine whether the incidence of CO2 embolism during EVH with CO2 insufflation could be reduced with lower CO2 insufflation pressure.

METHODS

Four hundred and ninety-eight consecutive patients scheduled for elective off-pump CABG were prospectively studied. These patients were randomly assigned into high and low groups in which 15 and 12 mm Hg CO2 insufflation pressures were used during EVH, respectively. Multiplane transesophageal echocardiography (TEE) with transgastric inferior vena cava view was used to monitor the appearances of CO2 bubbles. If a burst of many CO2 bubbles were found by TEE, the CO2 insufflation would be stopped until detailed examination of the operative field.

RESULTS

The incidence of CO2 embolisms in the high group of patients (13.3%) was significantly higher than that in the low group (6.5%, p < 0.05). Two episodes of emergent cessation of CO2 insufflation occurred in the high group of patients. No massive CO2 embolism with significant hemodynamic alterations occurred in either group.

CONCLUSIONS

The incidence of CO2 embolisms during EVH could be reduced with lower CO2 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 CO2 embolism.

Integrated coronary revascularization with drug-eluting stents: Immediate and seven-month outcome

OBJECTIVE

We sought to demonstrate the safety and feasibility of an integrated coronary revascularization strategy that combines minimally invasive left internal thoracic artery to left anterior descending coronary artery anastomosis with drug-eluting stent implantation to non-left anterior descending coronary artery lesions.

METHODS

Over 18 months, 47 consecutive patients with multivessel coronary artery disease underwent thoracoscopic harvesting of the left internal thoracic artery to graft the left anterior descending coronary artery. Anastomoses were constructed by hand, off-pump, and under direct vision through a 4-cm non-rib-spreading, muscle-sparing chest incision. Non-left anterior descending coronary artery lesions were then treated percutaneously using sirolimus- or paclitaxel-eluting stents. Angiographic follow-up was performed in all patients.

RESULTS

Within the first 90 days of hospitalizations, there were no deaths, myocardial infarctions, neurologic events, or wound complications. Forty patients underwent left internal thoracic artery to left anterior descending coronary artery grafting, and 7 patients underwent left internal thoracic artery to left anterior descending coronary artery/diagonal sequential grafting for a total of 54 anastomoses. Angiographic patency scores were FitzGibbon A 96.2% (52/54) and FitzGibbon A + B 100% (54/54). A total of 65 drug-eluting stents were implanted in 61 non-left anterior descending coronary artery coronary lesions of which 49.1% (30/61) were type B2 or C lesions, including 5 left main lesions. Diabetes was present in 53.2% of patients (25/47). At a mean follow-up time of 7.0 +/- 4.8 months, the target lesion or vessel repeat revascularization rate was 6.6% (4/61) for drug-eluting stents and 1.9% (1/54) for left internal thoracic artery to left anterior descending coronary artery grafting. One anastomosis required balloon dilation, but no patients have required repeat coronary artery bypass grafting.

CONCLUSIONS

Integrated coronary revascularization using drug-eluting stents is feasible and safe. There are sufficient data to justify a randomized comparison of integrated coronary revascularization with standard coronary artery bypass grafting.

Endothelial injury and acquired aspirin resistance as promoters of regional thrombin formation and early vein graft failure after coronary artery bypass grafting

OBJECTIVE

The predominant mechanism of early graft failure after coronary artery bypass grafting remains in doubt. Aspirin administered in the initial hours after coronary artery bypass grafting improves graft patency, implicating prostanoid synthesis in the pathogenesis. We hypothesized that synergy between endothelial disruption in the venous conduit and aspirin resistance would cause vein graft failure.

METHODS

Aspirin resistance, defined by diagnostic findings on at least two of three separate assays, was serially assessed in 225 patients undergoing off-pump coronary artery bypass grafting. Endothelial cell integrity was determined in surplus segments obtained from 408 vein grafts. The deposition of intraluminal thrombin within the vein was determined by comparing serum F1.2 levels between the coronary sinus and the aorta after grafting. Intraoperative blood flow in the grafts was measured with transit-time technology, and patency was assessed with electrocardiographically gated multichannel computed tomographic coronary angiography on day 5. Aspirin was the sole antithrombotic agent used during the study.

RESULTS

Thrombosed grafts (16/408) showed more endothelial cell loss at the time of grafting than did those grafts that remained patent (10.8% +/- 21.5% vs 51.4% +/- 39.1% integrity, P < .01). Aspirin resistance occurred in 67 patients (30%). Graft thrombosis was associated with aspirin resistance (P < .04) and reduced endothelial integrity (P < .01). These factors coexisted in 14 of 16 grafts that failed and were associated with elevated coronary sinus F1.2 levels.

CONCLUSION

Aspirin resistance and relatively compromised venous endothelial cell integrity together marked patients whose vein grafts failed within days after off-pump coronary artery bypass grafting. These observations form a basis for identifying patients at risk and developing approaches to prevent vein injury or to selectively intervene in high-risk circumstances.

Does Minimally Invasive Vein Harvesting Technique Affect the Quality of the Conduit for Coronary Revascularization?

The effect of minimally invasive great saphenous vein harvest on patient morbidity (wound infection and other healing disturbances) has been extensively investigated, yet its impact on the quality of the venous conduit is less well known. This study aims to review the literature with regard to macroscopic quality, postoperative myocardial infarction rates, and angiographic patency of the minimally invasive versus conventionally harvested vein using meta-analytic techniques where appropriate. Results suggest that conduits are comparable in macroscopic quality with minimally invasively harvested veins requiring more repairs prior to grafting. Postoperative myocardial infarction rates were not significantly different between groups, which is supported by the limited evidence on angiographic patency.