Bypass Conduit Research Articles

OC16 CORONARY ARTERY ENDARTERECTOMY DURING CORONARY ARTERY BYPASS GRAFTING: A SOLUTION FOR COMPLETE REVASCULARIZATION

Abstract Background: Coronary Artery Bypass Grafting (CABG) is one of the most frequently done cardiac surgical procedures. However, with the advancements in catheter-based interventional procedures, the category of patients taken up for CABG is gradually being restricted to more high-risk group. Performance of Off pump coronary artery bypass grafting (OPCAB) with concomitant coronary artery endarterectomy(CE) in patients with severe coronary disease provides more complete revascularization.We examined the technique and early outcomes of OPCAB with coronary endarterectomy (CE). Materials and methods: This is a single institutional retrospective study with 32 patients (26 males, 6 females) underwent concomitant off-pump CE and CABG from 1 october 2016 through 31 october 2017. which was about 11.26 % (32/284) of the OPCAB cases. Average number of coronary bypass grafts were 2.4 ± 0.8. 10 CE procedures were performed with saphenous vein patch. 7 involved left anterior descending artery (LAD) CE with left internal mammary artery (LIMA) conduits. The remaining 3 were diagonal branch artery (D1) CE with saphenous vein bypass conduits. Results: The incidence of postoperative MI was 9%. The 30-day mortality was 3.12% from complications of bowel ischaemia and three patients with septicaemia associated with prolonged intubation. The mean operating time was 138 ± 22 minutes. Conclusion: We have shown that the effect of OPCABG with CE appears to be safe and early outcomes are encouraging. Hence, diffuse disease requiring endarterectomy should not be considered a contraindication to OPCABG. Surgical skills and the suitability criteria of the patients are very important in this regard.

Long-Term Results of Femorotibial Polytetrafluoroethylene Bypass with a Distal Vein Cuff for Critical Limb Ischemia.

Objective: Although autologous veins are the first-choice conduit for femorotibial artery bypass, if there are no appropriate autologous veins, we perform femorotibial artery bypass using polytetrafluoroethylene (PTFE) with a distal vein cuff for patients with critical limb ischemia (CLI). This study examined the long-term outcomes of femorotibial artery bypass using PTFE with a Miller’s cuff.Materials and Methods: Using prospectively collected data for 444 distal bypasses, a retrospective analysis was conducted for 32 femorotibial PTFE bypasses with a Miller’s cuff (PTFE-Miller’s cuff) performed for patients with CLI from April 1994 to December 2016.Results: Primary and secondary patency rates of PTFE-Miller’s cuff at 3 years were 35.8% and 51.2%, respectively. Limb salvage rate of PTFE-Miller’s cuff at 3 years was 71.0%.Conclusion: Although the patency rate was low and failed to yield satisfactory results, the limb salvage rate remained relatively high. Femorotibial PTFE bypass with a Miller’s cuff was a useful technique of limb salvage for patients with CLI in whom an appropriate autologous vein could not be used.

The radial artery in coronary surgery, 2018.

It is now 25years since the radial artery (RA) was reintroduced in coronary surgery. It has evolved into being a significant coronary artery bypass conduit and ranks third in usage after the internal thoracic artery (ITA) and saphenous vein grafts (SVG). Its advantages are that it can be readily and efficiently harvested, is of good length and appropriate size for coronary artery bypass graft (CABG) surgery, is robust and easy to handle, and remains free of atheroma, and there is minimal wound morbidity. The RA must be used judiciously with attention to spasm prophylaxis because of its muscular wall, and by avoiding competitive flow. Its patency is equivalent to the ITAs when placed to similar coronary territories and under similar conditions (stenosis, size, quality) and RA patencies are always superior to those of SVG in both observational and randomized studies-88-90% versus 50-60% at 10years, and 80-87% versus 25-40% at 20years. Its use and excellent patencies result in survival results equivalent to bilateral internal thoracic artery (BITA) grafting and always superior to left internal thoracic artery (LITA) +SVG. Typical radial artery multiarterial bypass grafting (RA-MABG) 10-year survivals are 80-90% versus 70-80% for LITA-SVG. In general, for every 100 patients undergoing CABG, 10 more patients will be alive at 10years post-operatively. The RA also is important in achieving total arterial revascularization, and several reports indicate a further survival advantage for patients having three arterial grafts over two. The RAs are especially useful in diabetic, morbidly obese patients, those with conduit shortage, and leg pathology, and in coronary reoperations. Although the RA has equivalent patencies to the right internal thoracic artery (RITA), it is much more versatile. RAs that have been instrumented by angiography or percutaneous coronary intervention should be avoided. The radial artery has proved to be an excellent arterial conduit, is equivalent to but more versatile than the RITA, and is always superior to SVG. Its use should be part of every coronary surgeon's skill set.

Lessons learned from Radial Artery Database International ALliance (RADIAL).

Coronary artery bypass graft (CABG) surgery was first performed in the 1960s. As the surgery has evolved, there has been a growing interest in the use of multiple arterial grafts in CABG. Since the re-introduction of the radial artery (RA) to clinical use as a bypass conduit in the 1990s, there have been several randomized controlled trials (RCTs) which have compared saphenous vein graft (SVG) conduits to RA use in CABG. While most trials have shown improved patency of the RA, none of them have been able to demonstrate a survival benefit using the arterial conduit. In this review, we examine the existing RCTs on the subject. We then look at our solution to the decades-old inquiry regarding the RA compared with the SVG. The Radial Artery Database International ALliance (RADIAL) project is an individual patient-level meta-analysis developed to adequately power a study to assess if the RA has superior clinical outcomes compared with the SVG. We describe the process by which this investigation was conducted and the collaboration necessary to achieve success.

Increased warm ischemia time during vessel harvest decreases the primary patency of cryopreserved conduits in patients undergoing lower extremity bypass

ObjectiveAutologous vein is the preferred conduit for lower extremity bypass. However, it is often unavailable because of prior harvest or inadequate for bypass owing to insufficient caliber. Cryopreserved cadaveric vessels can be used as conduits for lower extremity revascularization when autogenous vein is not available and the use of prosthetic grafts is not appropriate. Many studies have shown that donor characteristics influence clinical outcomes in solid organ transplantation, but little is known regarding their impact in vascular surgery. The purpose of this study was to examine the effects donor variables have on patients undergoing lower extremity bypass with cryopreserved vessels. MethodsThe tissue processing organization was queried for donor blood type, warm ischemia times (WITs), and serial numbers of cryopreserved vessels implanted at a single center from 2010 to 2016. The serial numbers were then matched with their respective patients using the institutional Clinical Data Repository and patient data were obtained from the Clinical Data Repository and chart review. Primary outcomes were primary patency of the bypass conduits and limb salvage. Time to loss of patency was evaluated using Kaplan-Meier methods and a Cox proportional hazards model determined risk-adjusted predictors of patency and limb salvage. ResultsSixty patients underwent lower extremity bypass with 65 cryopreserved vessels (23 superficial femoral arteries, 41 saphenous veins, 1 femoral vein). Thirty-eight procedures were reoperations. There were 21 inflow, 44 outflow, and 44 infrainguinal procedures. Preexisting comorbidities did not differ significantly between those who lost patency and those who did not. The mean WIT among the entire cohort was 892.3 ± 389.1 minutes (range, 158.0-1434.0 minutes). The median follow-up was 394 days. Kaplan-Meier analysis demonstrated an overall 1-year primary patency rate of 51%. Primary patency at 1 year was 67% and 41% for inflow and outflow procedures, respectively, and did not differ significantly between the two groups (P = .15). Donor-to-recipient ABO incompatibility was not associated with loss of primary patency. The 1-year amputation-free survival was 74%. Primary patency significantly decreased with each hourly increase in WIT on risk-adjusted analysis (hazard ratio, 1.1; P = .02). ConclusionsHigher cryopreserved vessel WIT was associated with increased risk-adjusted loss of primary patency in this cohort. At 1 year, the overall primary patency was 51% and amputation-free survival was 74%. Vascular surgeons should be aware that WIT may affect outcomes for lower extremity bypass.

Abstract 489: Ex vivo Porcine Coronary Artery Remodeling With Seeded Endothelial Cells

Coronary heart disease is the most common cardiovascular problem that causes 370,000 deaths in America annually. Replacing the diseased coronary artery with a conduit obtained from another part of the patients’ body is the gold standard for the current surgical interventions. The great saphenous veins are widely preferred as coronary bypass grafts since they are easy to harvest and can replace multiple arteries due to their abundance. However, the endothelial cells in saphenous vein lose their venous characteristics and cannot function properly, which causes frequent graft failure. Conversely, arterial grafts have higher patency rate due to better function of endothelium. Yet, arterial grafts are not abundantly available as saphenous veins. Tissue engineered blood vessels can potentially serve as an ample source for bypass conduits. However, small-diameter engineered vessels are also tending to fail without a healthy endothelium. Here we propose to investigate the potential of Sox17-overexpressing endothelial cells in the vessel lumens to prevent intimal hyperplasia. Sox17 expression leads to upregulation of arterial, anti-thrombotic and anti-inflammatory markers in endothelial cells. We used an ex-vivo porcine coronary artery model where we cultured the vessels in perfusion bioreactors to mimic arterial flow conditions. Our preliminary results show that the vessel wall injury, seeded endothelial cells and arterial shear acted synergistically on smooth muscle cell death in the media layer (Fig. 1). The present ex vivo vessel culture platform is a promising tool to study remodeling by isolating factors like endothelial cells, soluble and mechanical factors.

Stratigraphic modeling of the Western Taiwan foreland basin: Sediment flux from a growing mountain range and tectonic implications

Abstract Sediment flux signals from source to sink in foreland basins preserve a record of tectonics, sea level and climate through erosion and sedimentation. However, longitudinal sediment transport often occurs in foreland basins, thus removing part of the orogenic material flux from foreland basin records. Here we use mass balance calculation and stratigraphic simulations of sediment fluxes for the Taiwan orogen to provide an order of magnitude estimate of how much orogenic material may bypass a foreland basin. Our results indicate a significant, potentially more than 50%, mismatch between sediment volume currently preserved in the basin and the amount of material presumably eroded from the orogen since the onset of collision in Taiwan. This suggests either a significant overestimation of average erosion rates over the period concerned with orogenic development of Taiwan, or it supports previous paleogeographic work suggesting that longitudinal sediment transport in the paleo-Taiwan Strait served as a major bypass conduit of importance for the establishment of a steady state orogen. We identify candidate submarine topography in the South China Sea that may preserve Taiwan's missing erosional mass.

PC198. Bovine Carotid Graft as a Conduit in Arterial Trauma

Although endovascular management of traumatic arterial injuries has become more common over the years, open reconstruction remains the mainstay of treatment. Autogenous vein is the preferred conduit for elective bypass, and, when feasible, traumatic injuries. When autogenous conduit is not available, or time does not permit harvest, bovine carotid artery graft (Artegraft, BCAG) is an option. While BCAG has been used for peripheral arterial disease treatment, there is Nothing to disclose on its use in vascular trauma. The purpose of this study was to review the experience with BCAG in vascular trauma at a single level 1 trauma center. The medical records of all patients with traumatic arterial injuries who underwent vascular bypass or interposition with bovine carotid artery from April 2014 to -October 2016 were retrospectively reviewed. Patient records were examined for patency, infection, and limb salvage. BCAG was used in 11 cases of arterial trauma which required open arterial reconstruction. For patients managed with BCAG, 8 were owing to penetrating trauma and 3 to blunt trauma. Patients ranged in age from 22 to 70 years (mean 35.8 years), eight male (73%), and three female (27%). Eighty-two percent involved the lower extremities, 9% involved the upper extremities, and 9% involved the carotid artery. Interventions included two iliofemoral, one femoral to above knee popliteal, two femoral to below knee popliteal or tibial, three SFA interposition grafts, one below the knee popliteal to tibial, one ulnar to radial bypass, and one carotid interposition. Follow-up ranged between 2 and 24 months (mean, 14 months). Based on most recent follow-up data, 64% of grafts had primary patency, while 82% had primary assisted patency. One graft occluded at 4 months in a patient with a posterior knee dislocation with a viable limb after failed attempts at graft salvage. There were no cases of graft or wound infection. There was one early failure, with resultant above knee amputation, on postoperative day 1. There were no deaths. While autologous vein remains the conduit of choice when feasible, traumatic situations do not always permit its use. BCAG is a suitable choice for traumatic arterial injuries when autogenous tissue is not available, either owing to time constraints or absence of suitable conduit. Further research will be needed to determine if BCAG is superior to prosthetic grafts for the trauma patients with arterial injuries.

One-Year Results of First-Line Treatment Strategies in Patients With Critical Limb Ischemia (CRITISCH Registry)

Purpose: To examine the outcomes of all first-line strategies for the treatment of critical limb ischemia (CLI), identify factors that influenced the treatment choice, and determine the risk of amputation or death after each treatment. Methods: CRITISCH (ClinicalTrials.gov identifier NCT01877252) is a multicenter, national, prospective registry evaluating all available treatment strategies applied in 1200 consecutive CLI patients in 27 vascular centers in Germany. The recruitment started in January 2013 and was completed in September 2014. Treatment options were endovascular revascularization (642, 53.5%), bypass surgery (284, 23.7%), femoral artery patchplasty (126, 10.5%) with or without concomitant peripheral intervention, conservative treatment (118, 9.8%), and primary major amputation (30, 2.5%). The primary endpoint of this study was amputation-free survival (AFS). The Society of Vascular Surgery’s suggested objective performance goal (OPG) for AFS (71%) was used as the effectiveness criterion. Multivariable regression methods were employed to identify variables that influenced the treatment selection and AFS after each treatment; results are presented as the hazard ratio (HR) and 95% confidence interval (CI). Results: The 12-month AFS estimates following endovascular therapy, bypass grafting, femoral patchplasty, and conservative treatment were 75%, 72%, 73%, and 72%, respectively. Factors influencing treatment choice were age, chronic kidney disease (CKD), diabetes, smoking, prior vascular procedures in the index leg, TransAtlantic Inter-Society Consensus II C/D lesions, and absence of runoff vessels. Cox regression analysis identified CKD (HR 2.07, 95% CI 1.26 to 3.41, p=0.004), the use of a prosthetic bypass conduit (HR 1.97, 95% CI 1.23 to 3.14, p=0.004), and previous vascular intervention in the index limb (HR 1.52, 95% CI 0.94 to 2.43, p=0.085) as independent risk factors for diminished AFS after bypass surgery. CKD (HR 1.47, 95% CI 1.09 to 1.99, p=0.012) and Rutherford category 6 (HR 1.81, 95% CI 1.30 to 2.52, p<0.001) compromised the performance of endovascular revascularization. Conclusion: CRITISCH registry data revealed that all first-line treatment strategies selected and indicated by the treating physicians met the suggested OPGs. CKD was an important determinant of patient prognosis after treatment regardless of the revascularization method.

Effect of CO2 Phase States and Flow Rate on Salt Precipitation in Shale Caprocks-A Microfluidic Study.

Fracture networks inside the caprock for CO2 storage reservoirs may serve as leakage pathways. Fluid flow through fractured caprocks and bypass conduits, however, can be restrained or diminished by mineral precipitations. This study investigates precipitation of salt crystals in an artificial fracture network as a function of pressure-temperature conditions and CO2 phase states. The impact of CO2 flow rate on salt precipitation was also studied. The primary research objective was to examine whether salt precipitation can block potential CO2 leakage pathways. In this study, we developed a novel microfluidic high-pressure high-temperature vessel to house geomaterial micromodels. A fracture network was laser-scribed on the organic-rich shales of the Draupne Formation, the primary caprock for the Smeaheia CO2 storage in Norway. Experimental observations demonstrated that CO2 phase states influence the magnitude, distribution, and precipitation patterns of salt accumulations. The CO2 phase states also affect the relationship between injection rate and extent of precipitated salts due to differences in solubility of water in CO2 and density of different CO2 phases. Injection of gaseous CO2 resulted in higher salt precipitation compared to liquid and supercritical CO2. It is shown that micrometer-sized halite crystals have the potential to partially or entirely clog fracture apertures.

Current Strategies for the Manufacture of Small Size Tissue Engineering Vascular Grafts.

Occlusive arterial disease, including coronary heart disease (CHD) and peripheral arterial disease (PAD), is the main cause of death, with an annual mortality incidence predicted to rise to 23.3 million worldwide by 2030. Current revascularization techniques consist of angioplasty, placement of a stent, or surgical bypass grafting. Autologous vessels, such as the saphenous vein and internal thoracic artery, represent the gold standard grafts for small-diameter vessels. However, they require invasive harvesting and are often unavailable. Synthetic vascular grafts represent an alternative to autologous vessels. These grafts have shown satisfactory long-term results for replacement of large- and medium-diameter arteries, such as the carotid or common femoral artery, but have poor patency rates when applied to small-diameter vessels, such as coronary arteries and arteries below the knee. Considering the limitations of current vascular bypass conduits, a tissue-engineered vascular graft (TEVG) with the ability to grow, remodel, and repair in vivo presents a potential solution for the future of vascular surgery. Here, we review the different methods that research groups have been investigating to create TEVGs in the last decades. We focus on the techniques employed in the manufacturing process of the grafts and categorize the approaches as scaffold-based (synthetic, natural, or hybrid) or self-assembled (cell-sheet, microtissue aggregation and bioprinting). Moreover, we highlight the attempts made so far to translate this new strategy from the bench to the bedside.

Open radial artery harvesting

The radial artery is a versatile bypass conduit that is being used with increasing frequency for an arterial coronary bypass strategy due to its excellent long-term patency and survival benefits. Open radial artery harvesting allows for careful dissection of the radial artery with minimal risk for endothelial damage, which helps to prevent vasospasm. Our technique for open radial artery harvesting and preparation is presented here.

Invited Commentary

Invited Commentary

Graft type for femoro-popliteal bypass surgery.

Graft type for femoro-popliteal bypass surgery.

Sex-based outcomes of lower extremity bypass surgery in hemodialysis patients

ObjectiveThe objective of this study was to compare conduit use and surgical outcomes of hemodialysis-dependent men and women after open lower extremity bypass surgery. MethodsUsing the United States Renal Data System, we studied all hemodialysis patients in the United States who underwent infrainguinal bypass surgery between January 1, 2006, and December 31, 2011. Univariate methods (χ2, analysis of variance) were employed to compare patient and bypass characteristics between men and women. Kaplan-Meier, univariate and multivariate logistic, and Cox regression analyses were employed to evaluate outcomes that included patency, graft failure, and mortality at 30 days. In addition, we compared limb salvage and patient survival rates between men and women. ResultsThere were 9739 bypasses performed in 5927 (61%) men and 3812 (39%) women who presented most commonly with critical limb ischemia (men, 73%; women, 71%; P = .04). Bypass configurations were femoral-popliteal (48%), femoral-tibial (34%), and popliteal-tibial (18%). The prevalence of autogenous conduits was higher for men (61 vs 55%; P < .001), and they were associated with higher patency compared with prosthetics (adjusted hazard ratio [aHR], 1.10; 95% confidence interval [CI], 1.01-1.19; P = .03). The risk-adjusted analyses revealed higher odds of acute graft failure for women compared with men who received prosthetic conduits (adjusted odds ratio, 1.23; 95% CI, 1.03-1.46; P = .021) but not among patients who received autogenous conduits (adjusted odds ratio, 1.07; 95% CI, 0.91-1.25; P = .41). Despite the difference in choice of conduit, there was no significant difference in primary patency (aHR, 1.00; 95% CI, 0.95-1.06; P = .90), primary assisted patency (aHR, 1.03; 95% CI, 0.97-1.10; P = .28), secondary patency (aHR, 1.01; 95% CI, 0.95-1.08; P = .75), limb salvage (aHR, 0.97; 95% CI, 0.90-1.04; P = .41), and survival (aHR, 0.97; 95% CI, 0.92-1.03; P = .45) for women compared with men. ConclusionsWe found lower use of autogenous conduits in women than in men. In patients who received prosthetic conduit, acute graft failure was higher for women than for men. The benefits of autogenous conduits over prosthetic grafts underscore the need to improve the selection of appropriately sized autogenous conduits for bypass irrespective of gender.

Endothelial Shear Stress of the Saphenous Vein Composite Graft Based on the Internal Thoracic Artery

Endothelial shear stress (ESS) has been suggested as a factor affecting atherosclerosis and remodeling of native vessels and bypass conduits. We compared ESS levels of internal thoracic artery (ITA) and saphenous vein (SV) composite grafts intraoperatively and 1 year after coronary artery bypass grafting (CABG). Intraoperative ESS was calculated by measuring flow volumes and diameters of proximal and distal ITAs and SV conduits in 23 patients who received SV Y-composite grafts based on the in situ left ITA. Early (1.2 ± 0.5 days) and 1-year (12.9 ± 1.1 months) postoperative angiograms were performed in 23 and 15 patients, respectively. An intragraft Doppler-guidewire study for ESS measurement was performed in 6 patients during 1-year angiography. Intraoperative diameters of proximal and distal ITAs and SV conduits were 2.0 ± 0.2 mm, 1.8 ± 0.3 mm, and 3.2 ± 0.4 mm, respectively. ESS levels were significantly different between them (41.0 ± 21.0, 28.4 ± 25.2, and 4.3 ± 3.0 dyne/cm2, respectively). Proximal and distal ITA diameters increased significantly on early angiograms and remained unchanged, but SV diameter increased to 3.7 mm (95% confidence interval, 3.5 to 4.0 mm; p < 0.001) on the early angiogram and decreased to 2.9 mm (95% confidence interval, 2.7 to 3.2 mm; p < 0.001) at 1 year. Significant correlations were found between the initial ESS and proportional changes in conduit diameters during postoperative year 1. SV ESS increased in all 6 patients at 1 year, with no significant differences in ESS levels between the 3 conduits (29.9 ± 7.9, 28.8 ± 7.9, and 21.6 ± 16.3 dyne/cm2, respectively). Initial ESS appears to be associated with proportional changes in conduit diameters in the first year after CABG. ESS values of SV composite grafts were similar to left ITA conduits 1 year after CABG.

Outcomes at a single center after subintimal arterial flossing with antegrade-retrograde intervention for critical limb ischemia

ObjectiveThe subintimal arterial flossing with antegrade-retrograde intervention technique has been used to overcome antegrade recanalization failures for peripheral lower limb arterial occlusive disease. There are few outcomes published for this technique and we sought to evaluate outcomes at our institution over a 7-year period. MethodsA retrospective review was performed of all subintimal arterial flossing with antegrade-retrograde intervention procedures of infrainguinal occlusive disease from 2009 to 2016. Retrograde and antegrade accesses were combined when occlusions could not be crossed from the antegrade direction. Baseline patient characteristics, procedures, procedure time, fluoroscopy time, contrast used, and radiation dose were collected. Posterior tibial waveforms, ankle-brachial index, limb salvage, vessel patency, and the presence of symptoms were assessed at follow-up. ResultsTreatment was performed in 52 limbs in 52 patients (35 men and 17 women; mean age, 77.62 ± 11.61 years) with critical limb ischemia and no appropriate venous conduit for surgical bypass. Among the cohort, 63.5% were diabetics, 98% had hypertension, 53.8% had a prior myocardial infarction, and 36.5% end-stage renal disease. The average Rutherford Category before the intervention was 5.08 ± 1.01. Retrograde pedal access was most commonly obtained in the anterior tibial artery/dorsalis pedis (55.7%), followed by the posterior tibial artery (40.3%). The technical success rate was 63.5% (33/52); adjunctive stenting was needed in 19 (36.5%) to optimize results. Preprocedural ankle-brachial index score was 0.54 ± 0.25, which improved after the procedure to an ankle-brachial index score of 0.77 ± 0.25. The primary patency rates at 3 and 6 months were 65% and 60%, respectively. The limb salvage rate at a mean follow-up of 5.4 months was 78.8%. There were 5 complications; 4 were hematomas managed conservatively and 1 was a major retroperitoneal bleed resulting in patient death. ConclusionsRetrograde pedal access is a viable revascularization technique for achieving limb salvage in patients with critical limb ischemia with acceptable patency for limb-threatening ischemia. This technique expands revascularization options after failed conventional endovascular antegrade approaches.

Invited Commentary

Invited Commentary

Vascular surgical stretch injury leads to activation of P2X7 receptors and impaired endothelial function.

A viable vascular endothelial layer prevents vasomotor dysfunction, thrombosis, inflammation, and intimal hyperplasia. Injury to the endothelium occurs during harvest and “back table” preparation of human saphenous vein prior to implantation as an arterial bypass conduit. A subfailure overstretch model of rat aorta was used to show that subfailure stretch injury of vascular tissue leads to impaired endothelial-dependent relaxation. Stretch-induced impaired relaxation was mitigated by treatment with purinergic P2X7 receptor (P2X7R) inhibitors, brilliant blue FCF (FCF) and A740003, or apyrase, an enzyme that catalyzes the hydrolysis of ATP. Alternatively, treatment of rat aorta with exogenous ATP or 2’(3’)-O-(4-Benzoyl benzoyl)-ATP (BzATP) also impaired endothelial-dependent relaxation. Treatment of human saphenous vein endothelial cells (HSVEC) with exogenous ATP led to reduced nitric oxide production which was associated with increased phosphorylation of the stress activated protein kinase, p38 MAPK. ATP- stimulated p38 MAPK phosphorylation of HSVEC was inhibited by FCF and SB203580. Moreover, ATP inhibition of nitric oxide production in HSVEC was prevented by FCF, SB203580, L-arginine supplementation and arginase inhibition. Finally, L-arginine supplementation and arginase inhibition restored endothelial dependent relaxation after stretch injury of rat aorta. These results suggest that vascular stretch injury leads to ATP release, activation of P2X7R and p38 MAPK resulting in endothelial dysfunction due to arginase activation. Endothelial function can be restored in both ATP treated HSVEC and intact stretch injured rat aorta by P2X7 receptor inhibition with FCF or L-arginine supplementation, implicating straightforward therapeutic options for treatment of surgical vascular injury.

Mechanisms, Consequences, and Prevention of Coronary Graft Failure.

Graft failure occurs in a sizeable proportion of coronary artery bypass conduits. We herein review relevant current evidence to give an overview of the incidence, pathophysiology, and clinical consequences of this multifactorial phenomenon. Thrombosis, endothelial dysfunction, vasospasm, and oxidative stress are different mechanisms associated with graft failure. Intrinsic morphological and functional features of the bypass conduits play a role in determining failure. Similarly, characteristics of the target coronary vessel, such as the severity of stenosis, the diameter, the extent of atherosclerotic burden, and previous endovascular interventions, are important determinants of graft outcome and must be taken into consideration at the time of surgery. Technical factors, such as the method used to harvest the conduits, the vasodilatory protocol, the storage solution, and the anastomotic technique, also play a major role in determining graft success. Furthermore, systemic atherosclerotic risk factors, such as age, sex, diabetes mellitus, hypertension, and dyslipidemia, have been variably associated with graft failure. The failure of a coronary graft is not always correlated with adverse clinical events, which vary according to the type, location, and reason for failed graft. Intraoperative flow verification and secondary prevention using antiplatelet and lipid-lowering agents can help reducing the incidence of graft failure.