Internal thoracic artery grafts: 20-year clinical follow-up

Reduced Morbidity and Mortality Associated With Minimally Invasive Single-vessel Coronary Artery Bypass Compared With Conventional Sternotomy

OBJECTIVE

We aimed to describe the safety and clinical benefits of minimally invasive, nonsternotomy coronary artery bypass grafting (MICABG) using data from The Society of Thoracic Surgeons (STS) National Database.

BACKGROUND

MICABG has gained popularity, owing to expected lower perioperative morbidity and shorter recovery. Despite this, concerns remain regarding anastomotic quality and the validity of proposed perioperative benefits.

METHODS

We queried the STS National Database for all patients who underwent single-vessel coronary artery bypass grafting (CABG) from January 2014 to December 2016 to compare outcomes of MICABG with conventional CABG. Patients who underwent concomitant or emergent procedures were excluded. Propensity-weighted cohorts were compared by operative approach with adjustment for variability across institutions.

RESULTS

Of 12,406 eligible patients, 2688 (21.7%) underwent MICABG, and 9818 (78.3%) underwent conventional CABG. Propensity weighting produced excellent balance in patient characteristics, including completeness of revascularization, body mass index, and STS predictive risk scores. MICABG was associated with significant reduction of in-hospital mortality [odds ratio (OR)=0.32, absolute reduction (AR)=0.91%, P <0.0001]; 30-day mortality (OR=0.51, AR=0.88%, P =0.001), duration of ventilation (8.62 vs 12.6 hours, P <0.0001), prolonged hospitalization (OR=0.77, AR=1.6, P =0.043), deep wound infection (OR=0.33, AR=0.68, P <0.004), postoperative transfusions (OR=0.52, AR=7.7%, P <0.0001), and STS composite morbidity (OR=0.72, AR=1.19%, P =0.008). Subgroup analysis of only off-pump left internal mammary artery-left anterior descending CABG showed similar findings. Major adverse cardiac events and graft occlusion did not differ between groups.

CONCLUSIONS

MICABG is associated with lower mortality and perioperative morbidity compared with conventional sternotomy CABG. MICABG may have a role in treating single-vessel disease.

Conduits' Biology Regulates the Outcomes of Coronary Artery Bypass Grafting

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Accelerated atherosclerosis is common when SVGs, but not arterial grafts, are used for myocardial revascularization during CABG.

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This review will provide an overview of the available data on the most commonly used conduits in CABG, highlighting the differences in their cellular biology, mechanical, biochemical, and vasoconstrictive properties.

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Clinical and scientific evidence support the use of arterial grafts over venous conduits at the time of CABG. These arterial conduits seem to be more protected toward the development of atherosclerosis. Exploring the molecular and cellular mechanisms, of the various cell populations within these conduits, will help unveil the pathways responsible for these protective effects.

Coronary artery bypass graft (CABG) is the gold standard for coronary surgical revascularization. Retrospective, prospective, and meta-analysis studies looking into long-term outcomes of using different conduits have pointed to the superiority of arterial grafts over veins and have placed the internal mammary artery as the standard conduit of choice for CABG. The superiority of the internal mammary artery over other conduits could be attributable to its intrinsic characteristics; however, little is known regarding the features that render some conduits atherosclerosis-prone and others atherosclerosis-resistant. Here, an overview is provided of the available data on the most commonly used conduits in CABG (internal mammary artery, saphenous vein, radial artery, gastroepiploic artery), highlighting the differences in their cellular biology, mechanical, biochemical, and vasoconstrictive properties. This information should help in furthering our understanding of the clinical outcomes observed for each of these conduits.

Outcomes following revascularization with radial artery bypass grafts: Insights from the PREVENT-IV trial

BACKGROUND

The optimal role of radial artery grafts in coronary artery bypass grafting (CABG) remains uncertain. The purpose of this study was to examine angiographic and clinical outcomes following CABG among patients who received a radial artery graft.

METHODS

Patients in the angiographic cohort of the PREVENT-IV trial were stratified based upon having received a radial artery graft or not during CABG. Baseline characteristics and 1-year angiographic and 5-year clinical outcomes were compared between patients.

RESULTS

Of 1,923 patients in the angiographic cohort of PREVENT-IV, 117 received a radial artery graft. These patients had longer surgical procedures (median 253 vs 228 minutes, P < .001) and had a greater number of grafts placed (P < .0001). Radial artery grafts had a graft-level failure rate of 23.0%, which was similar to vein grafts (25.2%) and higher than left internal mammary artery grafts (8.3%). The hazard of the composite clinical outcome of death, myocardial infarction, or repeat revascularization was similar for both cohorts (adjusted hazard ratio 0.896, 95% CI 0.609-1.319, P = .58). Radial graft failure rates were higher when used to bypass moderately stenotic lesions (<75% stenosis, 37% failure) compared with severely stenotic lesions (≥75% stenosis, 15% failure).

CONCLUSIONS

Radial artery grafts had early failure rates comparable to saphenous vein and higher than left internal mammary artery grafts. Use of a radial graft was not associated with a different rate of death, myocardial infarction, or postoperative revascularization. Despite the significant potential for residual confounding associated with post hoc observational analyses of clinical trial data, these findings suggest that when clinical circumstances permit, the radial artery is an acceptable alternative to saphenous vein and should be used to bypass severely stenotic target vessels.

Multiple Arterial Grafting Is Associated With Better Outcomes for Coronary Artery Bypass Grafting Patients

BACKGROUND

Observational studies have shown better survival in patients undergoing coronary artery bypass grafting (CABG) with 2 arterial grafts compared with 1. However, whether a third arterial graft is associated with incremental benefit remains uncertain. We sought to analyze the outcomes of 3 versus 2 arterial grafts during CABG. As a secondary objective, we compared CABG with 2 or 3 arterial grafts (multiple arterial grafts [MAG]) with CABG using a single arterial graft (SAG).

METHODS

Retrospective cohort analyses of all patients undergoing primary isolated CABG in Ontario, Canada, from October 2008 to March 2016. Propensity score matching was performed between patients with 3 arterial grafts (3Art group) versus 2 (2Art group). The primary outcome was time to first event of a composite of death, myocardial infarction, stroke, and repeat revascularization (major adverse cardiac and cerebrovascular events). Additional analyses were performed to evaluate the association between MAG versus SAG and long-term outcomes using propensity score matching.

RESULTS

Fifty thousand, two hundred thirty patients underwent isolated CABG during our study period; 3044 (6.1%) and 8253 (16.4%) patients had 3 and 2 arterial grafts, respectively, resulting in 2789 propensity score matching pairs for the primary analyses. Mean and maximum follow-up was 4.2 and 8.5 years, respectively. Radial artery grafting was more common in the 3Art versus 2Art group (79.3% versus 65.6%, P<0.01). In-hospital outcomes were not significantly different, including death (3Art 0.8% versus 2Art 0.5%, P=0.26). Up to 8 years, there were no differences in major adverse cardiac and cerebrovascular events (3Art 27%, 95% confidence interval [CI], 24% to 30% versus 2Art 25%, 95% CI, 22% to 28%; hazard ratio [HR], 1.08, 95% CI, 0.94-1.25), death (HR, 1.08; 95% CI, 0.90-1.29), myocardial infarction (HR, 1.15; 95% CI, 0.87-1.51), stroke (HR, 1.39; 95% CI, 0.95-2.06), or repeat revascularization (HR, 1.04; 95% CI, 0.82-1.32). When evaluating MAG versus SAG, 8629 patient pairs were formed using propensity score matching. At 8 years, cumulative incidences of major adverse cardiac and cerebrovascular events (HR, 0.82, 95% CI, 0.77-0.88), survival (HR, 0.80; 95% CI, 0.73-0.88), repeat revascularization (HR, 0.79; 95% CI, 0.69-0.90), and myocardial infarction (HR, 0.83; 95% CI, 0.72-0.97) were superior in the MAG group.

CONCLUSIONS

CABG with 3 arterial grafts was not associated with increased in-hospital death nor with better clinical outcomes at 8-year follow-up, compared with CABG with 2 arterial grafts. MAG was associated with superior outcomes compared with SAG.

[Microsurgical technique in coronary bypass surgery: possibilities, perspectives and limitations]

Microsurgical approach implies a special technique of operation under operating microscope with the use of special tools and ultra-thin atraumatic sutures. This method may be used in coronary artery bypass surgery in order to improve conventional technique, its quality and outcomes. The report summarizes information about technical features, capabilities and results of microsurgical coronary artery bypass grafting. The problem of popularizing microsurgical technologies in coronary bypass surgery is also discussed.

Minimally invasive single-vessel left internal mammary to left anterior descending artery bypass grafting improves outcomes over conventional sternotomy: A single-institution retrospective cohort study

BACKGROUND

Coronary artery bypass grafting (CABG) can be performed through a variety of approaches. Minimally-invasive CABG (MICABG) may reduce perioperative morbidity. Previous results demonstrate improved perioperative outcomes; however, adoption has been limited.

METHODS

The Society of Thoracic Surgeons (STS) database and electronic medical record at a single institution were reviewed for isolated left internal mammary to left anterior descending artery (LIMA-LAD) bypass procedures performed between 2011 and 2018. Patients were grouped on the basis of operative approach, comparing sternotomy to non-sternotomy (minimally-invasive). Patient characteristics, perioperative variables, and short- and long-term outcomes were compared. Primary outcomes included mortality and major adverse cardiac events (MACE). Secondary outcomes were morbidity.

RESULTS

A total of 42 MICABG and 54 conventional LIMA-LAD procedures were performed with 95.2% of MICABG procedures performed by two surgeons. MICABG were more often elective (83.3 vs 38.9%, P < .001). STS risk scores predicted equitable mortality and morbidity for MICABG dependent on operative indication. MICABG was associated with fewer pulmonary complications (0.0 vs 11.1%, P = .033), in-hospital events (11.9 vs 37.0%, P = .005), and shorter intensive care unit (34.1 vs 66.0 hours, P = .022) and total length of stay (3.7 vs 6.5 days, P = .002). There were no observed strokes, myocardial infarctions, or reoperations. MICABG patients demonstrated reduced thirty-day mortality (0.0 vs 10.9%, P = .036) and improved Kaplan-Meier 5-year (95.2 vs 77.9%, P = .016) and MACE-free survival (89.2 vs 63.9%, P = .010).

CONCLUSIONS

Minimally-invasive LIMA-LAD CABG demonstrates improved early postoperative morbidity and a long-term mortality benefit. In select patients, minimally-invasive approaches to single-vessel grafting may be beneficial when performed by experienced surgeons in the elective setting.

Surgical management of diffusely diseased coronary arteries

Purpose

To analyze the outcomes of long segment coronary anastomoses in patients with diffusely diseased coronary arteries and compare them with medically managed patients.

Methods

We retrospectively studied patients with diffusely diseased coronary arteries who underwent complete revascularization with long segment coronary reconstruction (> 2 cm in length) from February 2015 to November 2016. During the same time, patients who opted medical management for diffuse coronary artery disease were also studied.

Results

Forty-one patients underwent long segment coronary anastomoses for diffuse coronary artery disease with either left internal thoracic artery (LITA) or saphenous vein conduits. In 15 (36.58%) patients, the anastomosis length was more than 4 cm. In 41 patients, left anterior descending (LAD) artery had long segment anastomosis and in four patients, posterior descending artery (PDA) had long segment anastomosis. Twenty-one patients were operated off-pump and the rest were operated on cardiopulmonary bypass. The post-operative recovery of all the patients was uneventful. There were no procedural complications. There was one mortality due to cerebrovascular accident (2.43%). During the study period, 50 patients with diffuse coronary artery disease were under medical management. In the medically managed group, there were seven death during the follow-up, with mortality rate of 14%.

Conclusion

Patients with diffuse disease coronary diseases, who are surgically managed, have a better outcome when compared to the medically managed patients with acceptable morbidity and mortality.

[Microsurgery of coronary arteries using an operating microscope]

The world experience of coronary artery bypass surgery using an operating microscope is reviewed in the article. Important role of operating microscope and microsurgical techniques for coronary anastomoses formation is shown. High optical magnification provided by operating microscope directly affects the quality of surgical technique and accuracy of coronary anastomoses suturing that affects postoperative graft patency. Thus, the use of operating microscope can affect the results of coronary artery bypass surgery, as shown in several reports.

Long-term graft patency after coronary artery bypass grafting: Effects of surgical technique

The aim of the current study was to identify surgical factors associated with long-term patency of grafts used in coronary artery bypass grafting (CABG). The present study analyzed data from 127 patients who underwent CABG at our institute between 2000 and 2006 and presented for ambulatory examination and coronary computed tomography angiography evaluation of graft patency in 2016 (139.78±36.64 months post-CABG). The 127 patients received 340 grafts (2.68 grafts/patient) and 399 distal anastomoses (3.14 anastomoses/patient), 220 (55.14%) with arterial grafts and 179 (44.86%) with saphenous vein grafts. Graft patency varied according to coronary territory, proximal anastomosis type (in situ graft, composite graft, graft anastomosed to the ascending aorta), Y anastomosis angle (47.21° for patent arterial grafts vs. 56° for occluded), and distal anastomosis angle (in sequential anastomoses irrespective to graft type, 48.60° for patent side-to-side anastomosis vs. 53.97° for occluded, 65.12° for patent end-to-side anastomosis vs. 90.80° for occluded; in single end-to-side anastomosis of arterial grafts, 39.46° for patent and 44.94° for occluded). A single end-to-side anastomosis angle 60° or greater was associated with a 5.149 occlusion odds ratio (OR) (P<0.001) for arterial grafts. Venous grafts were not sensitive to single end-to-side anastomosis angle. In conclusion, a small anastomosis angle for proximal Y and distal anastomoses is associated with a higher long-term patency of the free graft. Radial artery grafts registered higher patency rates when anastomosed to the ascending aorta compared with composite grafting with the left internal thoracic artery, whereas in situ right internal thoracic artery (RITA) anastomosed to the right coronary territory is associated with a lower patency rate compared with free RITA used to revascularise the anterolateral or circumflex territory in composite grafting.

[The results of coronary artery bypass grafting by using of surgical microscope]

AIM

To analyze own experience of coronary artery bypass grafting (CABG) using microsurgical technique and operating microscope.

MATERIAL AND METHODS

There were 100 patients with coronary artery disease who underwent CABG in the Petrovsky Russian Research Center for Surgery for the period from April 2017 to December 2018. Mean age of patients was 59.7 ± 8.9 years. Triple-vessel disease was noted in 83 (83%) patients, two-vessel - in 17 (17%) patients. Stenosis of left main coronary artery was observed in 34 (34%) patients. On-pump myocardial revascularization using microsurgical technique was performed in all patients.

RESULTS

A total of 360 distal anastomoses with coronary arteries were formed in 100 patients using surgical microscope. Revascularization index was 3.6 ± 0.8, mean CPB time - 104 ± 24 min, aoric cross-clamping time - 72 ± 16 min. In-hospital mortality was absent. There were no cases of resternotomy for bleeding, infectious complications of postoperative wounds. One (1%) patient had intraoperative myocardial infarction.

CONCLUSION

CABG using microsurgical technique and operating microscope may be appropriate in patients with multiple-vessel coronary lesion and small diameter of coronary arteries.

CD90 Identifies Adventitial Mesenchymal Progenitor Cells in Adult Human Medium- and Large-Sized Arteries

Mesenchymal stem cells (MSCs) reportedly exist in a vascular niche occupying the outer adventitial layer. However, these cells have not been well characterized in vivo in medium- and large-sized arteries in humans, and their potential pathological role is unknown. To address this, healthy and diseased arterial tissues were obtained as surplus surgical specimens and freshly processed. We identified that CD90 marks a rare adventitial population that co-expresses MSC markers including PDGFRα, CD44, CD73, and CD105. However, unlike CD90, these additional markers were widely expressed by other cells. Human adventitial CD90+ cells fulfilled standard MSC criteria, including plastic adherence, spindle morphology, passage ability, colony formation, and differentiation into adipocytes, osteoblasts, and chondrocytes. Phenotypic and transcriptomic profiling, as well as adoptive transfer experiments, revealed a potential role in vascular disease pathogenesis, with the transcriptomic disease signature of these cells being represented in an aortic regulatory gene network that is operative in atherosclerosis.

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We identify, in situ and in vivo, adventitial CD90+ MSCs in human arteries

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Human adventitial CD90+ cells fulfill all criteria for an MSC population

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Other markers, such as CD44 and PDGFRα, were non-specific for adventitial MSCs

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The CD90+ MSC transcriptomic signature suggests a major role in vascular disease

Percutaneous management of ostial stenosis of the left internal mammary artery graft

A 61-year-old man, who had undergone coronary artery bypass surgery 10 years earlier, presented with a non-ST segment elevation myocardial infarction. He was treated with medical therapy and taken to the Cardiac Catheterization Laboratory. A left heart catheterization demonstrated an ostial stenosis in the left internal mammary artery graft, which was felt to be the culprit lesion. This was successfully repaired with a drug eluting stent. This case is presented as an unusual location for a de novo coronary stenosis. The pathophysiology of these lesions is not well understood.

Coronary artery bypass grafting in patients treated with thoracic radiation: a case-control study

Background and aim

Thoracic radiation therapy (XRT) for cancer is associated with the development of significant coronary artery disease that may require coronary artery bypass grafting surgery (CABG). Contemporary acute surgical outcomes and long-term postoperative survival of patients with prior XRT have not been well characterised.

Methods

This was a retrospective, single-centre study of patients with a history of thoracic XRT who required CABG and who were propensity matched against 141 controls who underwent CABG over the same time period. The objectives were to assess early CABG outcomes and long-term survival in patients with prior XRT.

Results

Thirty-eight patients with a history of previous thoracic XRT underwent CABG from 1994 to 2013. The median time from XRT exposure to surgery was 7.9 years (IQR: 2.5–18.4 years). Perioperative adverse events were similar in the XRT group and controls; however, there was a trends lower utilisation of internal mammary artery (IMA) grafts in the XRT group (89%vs98%, P=0.13). After a median postoperative follow-up of 5.4 years (IQR 0.9–9.4 years), no difference in long-term all-cause mortality was observed.

Conclusion

Patients with prior thoracic XRT who undergo CABG have similar long-term all-cause mortality compared with controls. Isolated CABG after thoracic XRT is not associated with higher perioperative complications, but IMA graft use may be limited by prior XRT.

Management and Prevention of Saphenous Vein Graft Failure: A Review

Coronary artery bypass grafting (CABG) remains a vital treatment for patients with multivessel coronary artery disease (CAD), especially diabetics. The long-term benefit of the internal thoracic artery graft is well established and remains the gold standard for revascularization of severe CAD. It is not always possible to achieve complete revascularization through arterial grafts, necessitating the use of saphenous vein grafts (SVG). Unfortunately, SVGs do not have the same longevity, and their failure is associated with significant adverse cardiac outcomes and mortality. This paper reviews the pathogenesis of SVG failure, highlighting the difference between early, intermediate, and late failure. It also addresses the different surgical techniques that affect the incidence of SVG failure, as well as the medical and percutaneous prevention and treatment options in contemporary practice.

Percutaneous revascularization in patients treated with thoracic radiation for cancer

OBJECTIVES

To assess coronary revascularization outcomes in patients with previous thoracic radiation therapy (XRT).

BACKGROUND

Previous chest radiation has been reported to adversely affect long term survival in patients with coronary disease treated with percutaneous coronary interventions (PCI).

METHODS

Retrospective, single center cohort study of patients previously treated with thoracic radiation and PCI. Patients were propensity matched against control patients without radiation undergoing revascularization during the same time period.

RESULTS

We identified 116 patients with radiation followed by PCI (XRT-PCI group) and 408 controls. Acute procedural complications were similar between groups. There were no differences in all-cause and cardiac mortality between groups (all-cause mortality HR 1.31, P=.078; cardiac mortality 0.78, P=.49).

CONCLUSION

Patients with prior thoracic radiation and coronary disease treated with PCI have similar procedural complications and long term mortality when compared to control subjects.

Does a similar procedure result in similar survival for women and men undergoing isolated coronary artery bypass grafting?

OBJECTIVES

To (1) identify sex-related differences in risk factors and revascularization strategies for patients undergoing coronary artery bypass grafting (CABG), (2) assess whether these differences influenced early and late survival, and (3) determine whether clinical effectiveness of the same revascularization strategy was influenced by sex.

METHODS

From January 1972 to January 2011, 57,943 adults-11,009 (19%) women-underwent primary isolated CABG. Separate models for long-term mortality were developed for men and women, followed by assessing sex-related differences in strength of risk factors (interaction terms).

RESULTS

Incomplete revascularization was more common in men than women (26% vs 22%, P < .0001), but women received fewer bilateral internal thoracic artery (ITA) grafts (4.8% vs 12%; P < .0001) and fewer arterial grafts (68% vs 70%; P < .0001). Overall, women had lower survival than men after CABG (65% and 31% at 10 and 20 years, respectively, vs 74% and 41%; P ≤ .0001), even after risk adjustment. Incomplete revascularization was associated equally (P > .9) with lower survival in both sexes. Single ITA grafting was associated with equally (P = .3) better survival in women and men. Although bilateral ITA grafting was associated with better survival than single ITA grafting, it was less effective in women-11% lower late mortality (hazard ratio, 0.89 [0.77-1.022]) versus 27% lower in men (hazard ratio, 0.73 [0.69-0.77]; P = .01).

CONCLUSIONS

Women on average have longer life expectancies than men but not after CABG. Every attempt should be made to use arterial grafting and complete revascularization, but for unexplained reasons, sex-related differences in effectiveness of bilateral arterial grafting were identified.

Endothoracic Papaverine Application for Internal Thoracic Artery Harvest

This study compared the effects of different methods of papaverine application on free blood flow and harvesting time of the internal thoracic artery for coronary bypass grafting. Patients were randomly divided into 3 groups of 25 each: group 1 had papaverine injected into the endothoracic tissue around the internal thoracic artery before dissection, group 2 had papaverine injected into the periarterial tissues of the internal thoracic artery pedicle, and group 3 had intraluminal papaverine applied retrogradely into the internal thoracic artery. Mean blood flow was 56.3 ± 21.3, 21.1 ± 13.2, and 20.9 ± 9.1 mL · min−1 in groups 1, 2, and 3, respectively, immediately after harvesting. Flow in group 1 was significantly better than that in groups 2 and 3. Immediately before anastomosis, mean flow was 89.8 ± 19.1, 97.6 ± 35.4, and 95.9 ± 19.9 mL · min−1 in groups 1, 2, and 3, respectively, with no significant difference among groups. Internal thoracic artery harvesting times were shorter in group 1 than in groups 2 and 3. Administering papaverine into the endothoracic fascia of the internal thoracic artery bed prior to dissection is a reliable method that facilitates rapid harvesting of the graft without causing trauma and consequent spasm.

Left Subclavian Artery Revascularization in Preparation for Coronary Artery Bypass Grafting

Coronary subclavian steal syndrome is a rare but important condition that occurs after a left internal mammary artery (LIMA) to coronary artery bypass in the setting of a stenotic left subclavian artery. The lack of blood flow through the subclavian artery causes the reversal of flow in the LIMA so that it essentially steals blood from the myocardium. In order to avoid this complication, many surgeons now opt to either revascularize the stenotic subclavian artery prior to coronary artery bypass grafting or to use an alternate vessel as the bypass graft. Here, we present the case of an asymptomatic patient with poor exercise tolerance who was recently diagnosed with both triple-vessel coronary disease and peripheral arterial disease, which was most notably characterized by occlusion of the left subclavian artery. This case demonstrates the surgical management of this complex clinical entity.

Hypoxia Differentially Regulates Arterial and Venous Smooth Muscle Cell Migration

OBJECTIVE

Intimal hyperplasia (IH) is a clinical concern leading to failure of up to 50% of vein grafts and 10% of arterial grafts after 10 years with no known current treatment. Recent studies have shown that hypoxia differentially regulates proliferation of vein derived smooth muscle cells (V-SMC) compared to artery derived smooth muscle cells (A-SMC). The objective of this study is to evaluate the effect of hypoxia on cellular migration and the mechanisms underlying the differential effects of hypoxia on A-SMC and V-SMC migration.

METHODS AND RESULTS

Hypoxic treatment (3-5% O2) of Smooth Muscle Cells (SMC) resulted in differential migration in scratch wound and electric cell substrate impedance sensing (ECIS) assays. Hypoxia led to greater migration compared to normoxia with venous derived wound closure (V-SMC 30.8% Normoxia to 67% Hypoxia) greater than arterial wound closure (A-SMC 6.2% Normoxia to 24.7% Hypoxia). Paracrine factors secreted by hypoxic endothelial cells induced more migration in SMC compared to factors secreted by normoxic endothelial cells. Migration of V-SMC was greater than A-SMC in the presence of paracrine factors. Neutralizing antibody to Vascular Endothelial Growth Factor Receptor -1 (VEGFR-1) completely inhibited V-SMC migration while there was only partial inhibition of A-SMC migration. A-SMC migration was completely inhibited by Platelet Derived Growth Factor BB (PDGF-BB) neutralizing antibody. p38 Mitogen Activated Protein kinase (p38 MAPK) inhibitor pre-incubation completely inhibited migration induced by paracrine factors in both A-SMC and V-SMC.

CONCLUSION

Our study determines that SMC migration under hypoxia occurs via both an autocrine and paracrine mechanism and is dependent on Vascular Endothelial Growth Factor-A (VEGF-A) in V-SMC and PDGF-BB in A-SMC. Migration of both A-SMC and V-SMC is inhibited by p38 MAPK inhibitor. These studies suggest that pharmacotherapeutic strategies directed at modulating p38 MAPK activity can be exploited to prevent IH in vascular grafts.

Save or sacrifice the internal mammary pedicle during anterior mediastinotomy?

Ligation and dissection of internal mammary vessels is the most under-estimated complication of anterior mediastinotomy. However, patients requiring anterior mediastinotomy may experience long survival that makes the development of ischemic heart disease throughout their life possible. Therefore, the un-judicial sacrifice of the internal mammary pedicle may deprive them from the benefit to have their internal mammary artery used as a graft in order to successfully bypass severe left anterior descending artery stenoses. We recommend the preservation of the internal mammary pedicle during anterior mediastinotomy, which should be a common message among our colleagues from the beginning of their training.

Coronary artery bypass graft: why is the saphenous vein prone to intimal hyperplasia?

Proliferation and migration of smooth muscle cells and the resultant intimal hyperplasia cause coronary artery bypass graft failure. Both internal mammary artery and saphenous vein are the most commonly used bypass conduits. Although an internal mammary artery graft is immune to restenosis, a saphenous vein graft is prone to develop restenosis. We found significantly higher activity of phosphatase and tensin homolog (PTEN) in the smooth muscle cells of the internal mammary artery than in the saphenous vein. In this article, we critically review the pathophysiology of vein-graft failure with detailed discussion of the involvement of various factors, including PTEN, matrix metalloproteinases, and tissue inhibitor of metalloproteinases, in uncontrolled proliferation and migration of smooth muscle cells towards the lumen, and invasion of the graft conduit. We identified potential target sites that could be useful in preventing and (or) reversing unwanted consequences following coronary artery bypass graft using saphenous vein.

Vascular grafts

Autogenous vein is the conduit of choice in the surgical creation of bypasses of small-to-medium-caliber vessels in patients with peripheral occlusive arterial disease and will remain so for the near future. The success rate of bypasses using conduits of diameters greater than 6 mm has been excellent, whereas the majority of bypasses using smaller conduits fail within 5 years. In addition, due to a steep increase in rates of diabetes and decreasing cardiovascular mortality rates, increasing challenges are presented by this population. These facts have motivated much of the research in the cardiovascular arena over the past four decades, with improved techniques and new materials. Strategies to improve outcomes include the use of alternative materials including autologous, nonautologous and prosthetic grafts, utilizing different methods for their harvesting and preservation; tissue engineering, using either polymer- or biological-based scaffolds for cell seeding; endovascular methodologies; and gene therapy. This report presents an overview of the several options currently available in the management of patients with peripheral arterial occlusive disease, as well as the ongoing research directed towards the creation of an artificial engineered vessel, discussing experimental work in which endothelial cells have been seeded on different scaffolds and finally the potential application of gene therapy in the field of vascular reconstruction.

Adoption and effectiveness of internal mammary artery grafting in coronary artery bypass surgery among Medicare beneficiaries

OBJECTIVES

The aim of this study was to assess the pattern of the adoption of internal mammary artery (IMA) grafting in the United States, test its association with clinical outcomes, and assess whether its effectiveness differs in key clinical subgroups.

BACKGROUND

The effect of IMA grafting on major clinical outcomes has never been tested in a large randomized trial, yet it is now a quality standard for coronary artery bypass graft (CABG) surgery.

METHODS

We identified Medicare beneficiaries ≥66 years of age who underwent isolated multivessel CABG between 1988 and 2008, and we documented patterns of IMA use over time. We used a multivariable propensity score to match patients with and without an IMA and compared rates of death, myocardial infarction (MI), and repeat revascularization. We tested for variations in IMA effectiveness with treatment × covariate interaction tests.

RESULTS

The IMA use in CABG rose slowly from 31% in 1988 to 91% in 2008, with persistent wide geographic variations. Among 60,896 propensity score-matched patients over a median 6.8-year follow-up, IMA use was associated with lower all-cause mortality (adjusted hazard ratio: 0.77, p < 0.001), lower death or MI (adjusted hazard ratio: 0.77, p < 0.001), and fewer repeat revascularizations over 5 years (8% vs. 9%, p < 0.001). The association between IMA use and lower mortality was significantly weaker (p ≤ 0.008) for older patients, women, and patients with diabetes or peripheral arterial disease.

CONCLUSIONS

Internal mammary artery grafting was adopted slowly and still shows substantial geographic variation. IMA use is associated with lower rates of death, MI, and repeat coronary revascularization.

Angiographic outcomes of radial artery versus saphenous vein in coronary artery bypass graft surgery: a meta-analysis of randomized controlled trials

INTRODUCTION

The efficacy of coronary artery bypass graft (CABG) surgery for patients with ischemic heart disease is dependent on the patency of the selected conduit. The left internal thoracic artery is considered to be the best conduit for CABG. However, the preferred conduit between the radial artery (RA) and saphenous vein (SV) remains controversial. The present meta-analysis aims to establish the current level IA evidence on patency outcomes comparing the RA and SV.

METHODS

Electronic searches were performed using 6 databases from their inception to March 2012. Two reviewers independently identified all relevant randomized controlled trials (RCTs) comparing patency outcomes of RA and SV grafts after CABG. Data were extracted and meta-analyzed according to angiographic end points at specified follow-up intervals.

RESULTS

Five relevant RCTs were identified for inclusion in the present meta-analysis. Angiographic results indicated that the RA was significantly more likely to be completely patent and less likely to be associated with graft failure or complete occlusion at 4 years' follow-up and beyond. However, the RA was significantly more likely to be associated with string sign at 1 year of follow-up.

CONCLUSIONS

While acknowledging the limitations of heterogeneous surgical techniques, results from the present meta-analysis suggest potential superiority of the RA compared with the SV at midterm angiographic follow-up. However, the increased incidence of string sign associated with the RA is of potential clinical concern. Further research should be directed at correlating angiographic findings of string sign and graft failure to clinical symptoms and major adverse cardiac and cerebrovascular events at long-term follow-up.

Choice of conduit for coronary artery bypass grafting in poor ventricles

Background: advantages in the use of arterial grafts for coronary artery revascularizations have been reported previously.

Objectives: we aimed to compare the outcome and survival rates of different conduits in patients with poor ventricular function (ejection fraction <30%).

Methods: in a 10-year period, 979 patients with an ejection fraction <30%, who underwent isolated first-time coronary artery bypass grafting, were divided into in 3 groups: (A) total arterial grafts ( n = 257), (B) total vein grafts ( n = 76), and (C) left internal mammary artery and vein grafts ( n = 610). Multivariate logistic regression was used to assess the effect of graft type on mortality, while adjusting for patient and disease characteristics. Hospital mortality and 5-year survival rates were compared among the groups.

Results: hospital mortality was 8.9% for group A, 11.8% for group B, and 5.7% for group C. Mortality at 5 years was 27.2% for group A, 42.3% for group B, and 28.7% for group C. After risk adjustment, hospital mortality and mid- and long-term mortality showed no significant differences among the groups.

Conclusions: patients with poor ventricular function have a high mortality rate in both the short- and long-term with any type of conduit. Mortality rates with total arterial grafts and vein plus arterial grafts were comparable before and after risk adjustment.

Effect of the degree of LAD stenosis on "competitive flow" and flow field characteristics in LIMA-to-LAD bypass surgery

The long-term patency of the left internal mammary artery (LIMA) in left anterior descending (LAD) coronary stenosis bypass surgery is believed to be related to the degree of competitive flow between the LAD and LIMA. To investigate the effect of the LAD stenosis severity on this phenomenon and on haemodynamics in the LIMA and anastomosis region, a numerical LIMA-LAD model was developed based on 3D geometric (obtained from a cast) and hemodynamic data from an experimental pig study. Proximal LAD pressure was used as upstream boundary condition. The model counted 13 outlets (12 septal arteries and the distal LAD) where flow velocities were imposed in systole, while myocardial conductance was imposed in diastole via an implicit scheme. LAD stenoses of 100 (total occlusion), 90, 75 and 0 % area reduction were constructed. Low degree of LAD stenosis was associated with highly competitive flow and low wall shear stress (WSS) in the LIMA, an unfavourable hemodynamic regime which might contribute to WSS-related remodelling of the LIMA and suboptimal long-term LIMA bypass performance.

Dual manganese-enhanced and delayed gadolinium-enhanced MRI detects myocardial border zone injury in a pig ischemia-reperfusion model

BACKGROUND

Gadolinium (Gd)-based delayed-enhancement MRI (DEMRI) identifies nonviable myocardium but is nonspecific and may overestimate nonviable territory. Manganese (Mn(2+))-enhanced MRI (MEMRI) denotes specific Mn(2+) uptake into viable cardiomyocytes. We performed a dual-contrast myocardial assessment in a porcine ischemia-reperfusion (IR) model to test the hypothesis that combined DEMRI and MEMRI identifies viable infarct border zone (BZ) myocardium in vivo.

METHODS AND RESULTS

Sixty-minute left anterior descending coronary artery IR injury was induced in 13 adult swine. Twenty-one days post-IR, 3-T cardiac MRI was performed. MEMRI was obtained after injection of 0.7 mL/kg Mn(2+) contrast agent. DEMRI was then acquired after injection of 0.2 mmol/kg Gd. Left ventricular (LV) mass, infarct, and function were analyzed. Subtraction of MEMRI defect from DEMRI signal identified injured BZ myocardium. Explanted hearts were analyzed by 2,3,5-triphenyltetrazolium chloride stain and tissue electron microscopy to compare infarct, BZ, and remote myocardium. Average LV ejection fraction was reduced (30±7%). MEMRI and DEMRI infarct volumes correlated with 2,3,5-triphenyltetrazolium chloride stain analysis (MEMRI, r=0.78; DEMRI, r=0.75; P<0.004). MEMRI infarct volume percentage was significantly lower than that of DEMRI (14±4% versus 23±4%; P<0.05). BZ MEMRI signal-to-noise ratio (SNR) was intermediate to remote and core infarct SNR (7.5±2.8 versus 13.2±3.4 and 2.9±1.6; P<0.0001), and DEMRI BZ SNR tended to be intermediate to remote and core infarct SNR (8.4±5.4 versus 3.3±0.6 and 14.3±6.6; P>0.05). Tissue electron microscopy analysis exhibited preserved cell structure in BZ cardiomyocytes despite transmural DEMRI enhancement.

CONCLUSIONS

The dual-contrast MEMRI-DEMRI detects BZ viability within DEMRI infarct zones. This approach may identify injured, at-risk myocardium in ischemic cardiomyopathy.

Dexamethasone arterializes venous endothelial cells by inducing mitogen-activated protein kinase phosphatase-1: a novel antiinflammatory treatment for vein grafts?

BACKGROUND

Vein grafting in coronary artery surgery is complicated by a high restenosis rate resulting from the development of vascular inflammation, intimal hyperplasia, and accelerated atherosclerosis. In contrast, arterial grafts are relatively resistant to these processes. Vascular inflammation is regulated by signaling intermediaries, including p38 mitogen-activated protein (MAP) kinase, that trigger endothelial cell (EC) expression of chemokines (eg, interleukin-8, monocyte chemotactic protein-1) and other proinflammatory molecules. Here, we have tested the hypothesis that p38 MAP kinase activation in response to arterial shear stress (flow) may occur more readily in venous ECs, leading to greater proinflammatory activation.

METHODS AND RESULTS

Comparative reverse-transcriptase polymerase chain reaction and Western blotting revealed that arterial shear stress induced p38-dependent expression of monocyte chemotactic protein-1 and interleukin-8 in porcine jugular vein ECs. In contrast, porcine aortic ECs were protected from shear stress-induced expression of p38-dependent chemokines as a result of rapid induction of MAP kinase phosphatase-1. However, we observed with both cultured porcine jugular vein ECs and perfused veins that venous ECs can be protected by brief treatment with dexamethasone, which induced MAP kinase phosphatase-1 to suppress proinflammatory activation.

CONCLUSIONS

Arterial but not venous ECs are protected from proinflammatory activation in response to short-term exposure to high shear stress by the induction of MAP kinase phosphatase-1. Dexamethasone pretreatment arterializes venous ECs by inducing MAP kinase phosphatase-1 and may protect veins from inflammation.

Radial artery versus saphenous vein conduits for coronary artery bypass surgery: forty years of competition--which conduit offers better patency? A systematic review and meta-analysis

The internal thoracic artery is the most effective conduit for coronary artery bypass surgery; however, most patients have multivessel disease and require additional saphenous vein or radial artery grafts. In this systematic review of the literature and meta-analysis, we aim to compare reported patency rates for these conduits and explore if differences are homogeneous across follow-up intervals. A literature search was performed using Embase, Medline, Cochrane Library, Google Scholar and randomised controlled trial databases to identify studies published between 1965 and October 2009. All studies reporting angiographic comparison of saphenous vein and radial artery conduit patency were included, irrespective of language. The end point was angiographic graft patency stratified over different follow-up intervals. Meta-analysis was performed according to recommendations from the Cochrane Collaboration and Meta-analysis Of Observational Studies in Epidemiology guidelines. We used a random-effect model and the odds ratio as the summary statistic. A total of 35 studies were identified. They reported early patency (≤ 1 year, 6795 grafts), medium-term patency (1-5 years, 3232 grafts) and long-term patency (>5 years, 1157 grafts). Significant variation of comparative patency existed across different follow-up intervals. Early saphenous vein patency was similar to radial artery patency with odds ratio of 1.04 (95% confidence interval 0.68-1.61). Medium-term saphenous vein patency, however, deteriorated significantly (odds ratio 2.06, 95% confidence interval 1.29-3.29). Similarly, long-term patency was better for radial artery conduits (odds ratio 2.28, 95% confidence interval 1.32-3.94). Heterogeneity was due to angiographic patency characteristics and related to risk of bias. In conclusion, the findings of this systematic review of the published literature and meta-analysis support the use of radial artery in preference to saphenous vein conduits for coronary artery bypass surgery.

Evaluation of patients after coronary artery bypass grafting

Modern techniques for coronary artery bypass graft (CABG) are highly successful. Nevertheless, over time, grafts do fail and native coronary artery disease does progress. Follow-up of patients after CABG should focus on secondary prevention, including careful attention to all modifiable risk factors for cardiovascular disease. Routine stress testing with or without imaging is usually not necessary if the patient is asymptomatic and engaging in normal physical activities, including moderate exercise without difficulty. Stress testing with electrocardiographic monitoring alone or in conjunction with nuclear myocardial perfusion imaging or echocardiography is commonly used if a patient develops recurrent symptoms post-CABG or is at particular high risk for complications. Computed tomography coronary angiography is a new, very powerful, noninvasive technique that can directly visualize both CABG and the native coronary arteries. Computed tomography coronary angiography is complimentary to functional stress testing in that it provides anatomic information about graft patency and native coronary artery stenoses, but the functional significance of these findings may still require stress testing with nuclear or ultrasound imaging. Further technical improvements, both in surgical techniques and in imaging, and prospective multicenter trials, are needed to better define the best methods for following patients post-CABG.

Atrial fibrillation independently prolongs hospital stay after coronary artery bypass surgery

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia occurring in patients after coronary artery bypass surgery (CABG).

HYPOTHESIS

The purpose of this study was to determine whether AF independently prolonged postoperative length of stay (LOS).

METHODS

Consecutive patients undergoing elective CABG were identified. Baseline clinical variables, postoperative course including the development of AF, and postoperative LOS were recorded.

RESULTS

In all, 216 patients (aged 61 +/- 13 years) were examined. Postoperative LOS was 11.3 +/- 6.4 days (median LOS = 9 days). Fifty-five patients (25%) developed AF. Among 16 variables examined, the univariate predictors of LOS included age (p < 0.001), preoperative left ventricular ejection fraction (p < 0.001), absence of a prior smoking history (p < 0.05), bypass limited to venous conduits (p < 0.001), postoperative AF (p < 0.001), and the occurrence of a postoperative event (p < 0.001). Length of stay for patients who developed AF was significantly longer than that for patients who did not (15.1 +/- 9.0 vs. 10.0 +/- 4.6 days, p < 0.001). After adjusting for other significant variables, the occurrence of AF after CABG independently prolonged LOS: patients who developed AF stayed 3.2 +/- 1.7 days longer than patients who did not (p < 0.001).

CONCLUSIONS

Atrial fibrillation lengthens hospital stay after CABG, and its effect is independent of other important variables. Identification of patients who are at risk for AF and successful treatment to prevent AF will likely contribute to major reductions in consumption of health care resources in patients with CABG.

Total arterial myocardial revascularization

Failure of saphenous vein graft conduits is the most common indication for coronary artery reintervention after coronary artery bypass surgery. To estimate the feasibility and efficacy of total arterial myocardial revascularization in our patients, routine use of pedicled bilateral internal mammary arteries with or without a radial artery was applied in our department for the past 7 years in 1825 consecutive patients. Total arterial revascularization was achieved in 1817 of 1825 consecutive patients (99.5%), with 5815 coronary anastomoses using only bilateral mammary arteries with or without a radial artery. Combined procedures were performed in 345 (18.9%) of the cases. Preoperative mean additive Euroscore was 7.4, and the early mortality rate was 2.6%. Regular use of both mammaries and radial artery in patients requiring myocardial revascularization is a feasible and efficient technique, and it is highly recommended as a gold standard.