The internal mammary arteries (IMAs) are commonly used as the conduit to bypass major coronary artery stenosis, and have shown greater long-term patency rates and improved survival as compared to saphenous vein grafts (SVGs) ( 1, 2 ).
What are the benefits of internal mammary artery (IMA) grafts?
Email: [email protected]. The internal mammary artery (IMA) grafts have been associated with long-term patency and improved survival as compared to saphenous vein grafts (SVGs). Early failure of IMA is attributed to poor surgical technique and less with thrombosis.
What are internal mammary arteries used for?
The internal mammary arteries (IMAs) are commonly used as the conduit to bypass major coronary artery stenosis, and have shown greater long-term patency rates and improved survival as compared to saphenous vein grafts (SVGs) (1,2).
Is the internal mammary artery (IMA) a suitable conduit for bypass surgery?
Keywords: Coronary artery disease, internal mammary artery (IMA), pathology, saphenous vein graft (SVG) The internal mammary arteries (IMAs) are commonly used as the conduit to bypass major coronary artery stenosis, and have shown greater long-term patency rates and improved survival as compared to saphenous vein grafts (SVGs) ( 1, 2 ).
Is the internal mammary artery better than the superior vena cava?
Robust data and literature suggest that the internal mammary artery (IMA) undergoes minimal atherosclerotic changes and has excellent long term outcomes and patient survival compared to superior vena cava graft (SVG). Its survival and patency rates are much better as compared to venous and even other arterial grafts.
What is the advantage of using the mammary artery?
The use of the internal mammary artery reduces the incidence of late adverse effects and improves survival after coronary artery bypass grafting.
Why is the left internal mammary artery used for CABG?
Ross Reul, a cardiothoracic surgeon at Houston's Methodist Hospital, noted that the LIMA is now used in 98% of CABG cases. It is considered the gold standard because of its long-term patency, and the superior mortality rate and the decreased morbidity of patients who receive it.
Which artery is most commonly used for bypass graft?
Internal thoracic artery As the most commonly used bypass grafts, the internal thoracic (mammary) artery (ITA) grafts show the best long-term results. In most cases, the artery is left intact at its origin, with the opposite end sewn to the coronary artery below the site of the blockage.
How is the mammary artery used in bypass surgery?
If you need 2, 3 or 4 grafts, you may hear your operation referred to as a double, triple or quadruple bypass. One of the graft vessels is usually taken from your chest (internal mammary artery). Surgeons prefer to use this vessel because it doesn't narrow over time, unlike the blood vessels taken from your leg or arm.
What does the left internal mammary artery supply?
The internal thoracic artery, aka the internal mammary artery, supplies the breast and the anterior chest wall. The internal thoracic artery travels along the inner surface of the anterior chest wall on both sides.
What is left internal mammary artery graft?
The left internal mammary artery is freed at one end from the chest and stitched to the opening of the coronary artery beyond the blockage in order to bypass the obstruction of blood flow. Unlike other grafts, the LIMA is not completely excised, but one end remains attached to the chest wall.
What is the longest vein commonly used in grafts in coronary bypass surgery?
The most commonly used graft was the saphenous vein (particularly the great saphenous vein) and is still in use. However, due to the success story of the left internal mammary artery LIMA, total arterial revascularization has gained much importance for coronary bypass graft surgery.
Where do they get arteries for bypass surgery?
Blood vessels, or grafts, used for the bypass procedure may be pieces of a vein from your leg or an artery in your chest. An artery from your wrist may also be used. Your doctor attaches one end of the graft above the blockage and the other end below the blockage.
Why is the greater saphenous vein used as the bypass?
Saphenous vein as bypass conduit This is because it is easily harvested and is technically easy to use due to its wall characteristics and large diameter. Also, because it is long and plentiful, it can reach any coronary artery and can be used to graft multiple vessels.
Does the breast bone grow back together after open heart surgery?
Does the sternum fully heal after heart surgery? Full recovery following a sternotomy is possible, but it is a long process. After surgery, the surgeon will use strong wire to hold the cut bones together, allowing new cells to grow. Over the course of months, the bones fuse back together.
How fast can arteries clog after bypass surgery?
Within a year after surgery, the vein segments can become blocked - about 15% of the time, which can lead to the recurrence of chest pain. “Improving the rate at which vein grafts remain open has always been a core issue of CABG surgery,” said cardiac surgeon Shengshou Hu, M.D., Ph.
Why do coronary artery bypass grafts fail?
After grafting, the implanted vein remodels to become more arterial, as veins have thinner walls than arteries and can handle less blood pressure. However, the remodeling can go awry and the vein can become too thick, resulting in a recurrence of clogged blood flow.
Where does the left internal mammary artery originate from?
The IMA originates from the subclavian artery and travels along the sternal border on each side of the sternum. It becomes the superior epigastric artery in the upper abdomen and nourishes the upper part of the rectus abdominis muscle.
Do men have internal mammary artery?
Linear regression was used to determine correlation of these parameters with age. Internal mammary arteries from women and men were of equal size.
Where is the internal mammary artery located?
The IMA is separated from the pleura at the second or third costal cartilage by a strong layer of endothoracic fascia and inferiorly by the transversus thoracis muscle. It is accompanied by two mammary veins, which ascend medially and laterally, respectively [18,19] .
What is left anterior descending artery?
The left anterior descending artery (LAD) is the largest coronary artery runs anterior to the interventricular septum in the anterior interventricular groove, extending from the base of the heart to the apex. The LAD gives two sets of branches.
Why is LIMA considered a bypass graft?
First, because its media is thinner and less muscular than other arteries and veins, it produces a higher basal and stimulated rate of nitric oxide and exhibits a lower propensity for spasm.
What is the magic of the left internal artery?
The Magic of the Left Internal Mammary Artery. The Left Internal Mammary Artery (LIMA), also known as the Left Internal Thoracic Artery (LITA), has been the gold standard conduit of choice for coronary artery bypass grafting (CABG) for several decades. More than 30 years ago, Boylan et al published a study in the Journal ...
When did the LIMA graft take place?
The operations took place from 1971 through 1973 when taking down the LIMA was still in its infancy. The study concluded that the LIMA-LAD graft, with an intervention-free survival of 60.5% after 18 years, yielded consistently better overall and intervention-free survival than did the SVG-LAD in patients who were surgically treated ...
Which side of the body is the distal anastomosis located?
Moreover, when used in situ, only one distal anastomosis is required rather than the two required by a vein graft. Its location on the left side of the body allows grafting to the LAD without producing tension on the vessel.
Why are IMA grafts failing?
Early IMA graft failure is most commonly attributed to technical errors with harvesting and the graft anastomosis. IMA grafts examined within the first week following distal anastomosis show an absence of neointimal thickening or there are only a few SMC along with proteoglycan and collagen. When IMA grafts are examined between 1 week and 2 months, the site of the anastomosis shows intimal thickening (0.08±0.07 mm) located at the cleft between the native artery and the IMA graft at the anastomotic suture site ( Figure 1) ( 15 ). The intimal thickening consisted of SMCs, proteoglycan, collagen and elastin fibers with luminal endothelial cells. However, in the body of the graft at this time, there are only occasional areas that show minimal intimal thickening consisting of a few SMCs in a proteoglycan matrix with or without collagen, likely due to manipulation of the artery at the time of surgery. Significant intimal thickening was observed in grafts implanted for 2 months to 10 years at the suture sites (0.39±0.17 mm) and on the hood (0.29±0.25 mm), while intimal thickening on the floor (native LAD) was observed in 10 of 18 IMA grafts (0.11±0.12 mm) ( Figure 2 ). Intimal thickening is similar in those grafts less than 1 year versus grafts greater than 1 year, suggesting that intimal thickness does not increase with time. The body of the IMA graft also showed the least intimal thickening as compared to the anastomotic site (10 of 18, 0.03±0.04 mm). Only rarely was an atherosclerotic change observed in the IMA. In our study, 2 of the 18 grafts examined 5.22±4.76 years following grafting, it was described as “small focal, infiltrates of lipid in the intima”.
How long do you live with a IMA graft?
Since the publication by Loop et al. in 1986 on 10-year survival of patients who received an IMA graft to the left anterior descending coronary artery (LAD) with or without one or more vein grafts versus patients who received only SVGs, which showed that the survival was higher with an IMA graft (93.4%) versus SVG (88.0%) for those with one-vessel disease, 90.0% versus 79.5% for two-vessel disease, and 82.6% versus 71.0% (P<0.0001) for those with three-vessel disease, the IMA has become the preferred choice for grafting the LAD ( 6 ). SVGs are known to undergo not only intimal thickening but also atherosclerosis, and angiographic studies demonstrated a 2% per year vein-graft attrition rate from the 1 st to the 7 th postoperative year, further increasing to 5% per year from the 7 th to the 12 th year ( 5 ). At 10-years, it has been reported that only 38% to 45% of SVG remain patent ( 6, 7 ). These studies have helped document the superiority of IMA graft over SVG.
What is the main vector of blood flow?
Blood flow creates two principal vectors on the vessel wall, one which is perpendicular to the wall and is determined by the blood pressure, and the other which is parallel to the vessel wall and creates frictional force and shear stress on the endothelial cells. Endothelial cells align in the direction of flow but the orientation is lost with flow disturbances. The stress on the surface of the endothelial cells leads to cytoskeleton changes that attach the endothelial cell to the subendothelial matrix and to adjacent cells, leading to increased resistance to deformation and impart stability. Endothelial cells sense shear-stress and are the principal endothelial regulator of arterial diameter, which may be related to the release of NO. Other substances that also mediate vaso-regulation include prostaglandin I2, endothelin-1, tissue plasminogen activator, ICAM-1, and transforming growth factor-β1 (TGF-β1). While the effects of NO are short-lived, NO synthesis is enhanced by the steady laminar flow that induced eNOS. The arterial remodeling seen in the IMA occurs over months and is a response to flow that result in changes in gene expression. Chronic flow increase results in enlargement of the arterial lumen whereas reduced flow induces intimal thickening and a reduction in vessel lumen. This has been demonstrated in the canine IMA following reduction of flow by ligation of the side branch ( 22 ). The IMA has an abundant collateral blood supply to its runoff bed, which also lead to the protection of the intima ( 23 ). Furthermore, the size of the IMA is close to the size of the coronary vessels, which may result in less turbulent flow as compared to the larger SVG conduits that are prone to develop atherosclerosis.
Why are IMAs better than SVGs?
Similarly, bypass surgery especially with the use of IMA has also been shown to be superior at 1-year as well as over five years compared to percutaneous procedures, including the use of drug-eluting stents for the treatment of coronary artery disease. The superiority of IMAs over SVGs can be attributed to its striking resistance to the development of atherosclerosis. Structurally its endothelial layer shows fewer fenestrations, lower intercellular junction permeability, greater anti-thrombotic molecules such as heparin sulfate and tissue plasminogen activator, and higher endothelial nitric oxide production, which are some of the unique ways that make the IMA impervious to the transfer of lipoproteins, which are responsible for the development of atherosclerosis. A better comprehension of the molecular resistance to the generation of adhesion molecules that are involved in the transfer of inflammatory cells into the arterial wall that also induce smooth muscle cell proliferation is needed. This basic understanding is crucial to championing the use of IMA as the first line of defense for the treatment of coronary artery disease.
What is the purpose of IMAs?
The internal mammary arteries (IMAs) are commonly used as the conduit to bypass major coronary artery stenosis, and have shown greater long-term patency rates and improved survival as compared to saphenous vein grafts (SVGs) ( 1, 2 ). The benefit of IMAs over SVGs on mortality has been consistently observed irrespective of age, gender, ...
What is the endothelium of IMA?
The IMA endothelium shows fewer fenestrations and lower intercellular junction permeability as compared to SVG, which could prevent lipoproteins from entering the subendothelial space. Segments of IMA collected at the time of surgery show a preserved morphology without any disturbance of endothelial cells or cautery burns, with uniform platelet endothelial cell adhesion molecule-1 (PECAM-1) staining, and strong expression of glucose transporter 1. Conversely, inducible nitric oxide synthase (iNOS) and intercellular adhesion molecule-1 (ICAM-1) are only moderately expressed on the luminal surface as well as on vasa vasorum of IMAs removed from patients with acute coronary syndrome or chronic stable angina ( 20 ). Endothelial cells of the IMA are rich in heparin sulfate and endothelial nitric oxide synthase (eNOS), and release a greater amount of nitric oxide (NO) that contributes to the antithrombotic properties and endothelial homeostasis which confers protection from atherosclerosis.
Is CABG better than angioplasty?
CABG has been the treatment of choice compared to balloon angioplasty since results from the Bypass Angioplasty Revascularization Investigation (BARI) trial in 1996, of patients with multi-vessel coronary disease, showed patients with CABG lived longer than patient undergoing balloon angioplasty ( 26 ). Since the advent of drug-eluting stents (DES), interventional cardiologists have contended that CABG may not be superior to stenting because of improved results with DES over bare metal stents or balloon angioplasty. With the use of 1 st -generation DES in the SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery (SYNTAX) study, it was shown that all cause death or myocardial infarction was not different in the two arms; however, repeat vascularization was significantly more frequent in PCI than CABG (13.5% vs. 5.9%, P<0.001) in the first year. The differences in myocardial infarction and repeat PCI have now been both shown to be significantly lower for CABG as compared to PCI at 3- and 5-years. These results are also similar to those in the recently published ASCERT study ( 27 ), which was a large non-randomized observational data from The Society of Thoracic Surgeons and the American College of Cardiology Foundation registries to evaluate effectiveness of revascularization with CABG compared to PCI. This too showed a benefit for CABG with a 4-year mortality of 16.4% in the CABG arm versus 20.8% in the PCI arm (risk ratio, 0.79; 95% confidence interval 0.76-0.82) ( 27 ). Similar results have also been published for the FREEDOM (Future Revascularization Evaluation in Patients with Diabetes Mellitus: Optimal Management of Multivessel Disease) trial. The primary outcome of composite of death from any cause, non-fatal myocardial infarction, or nonfatal stroke occurred more frequently in the PCI than in the CABG group (P=0.005), with 5-year rates of 26.6% in the PCI and 18.7% in the CABG group ( 28 ). Both the SYNTAX and the FREEDOM trials had over 94% of patients undergoing left IMA to LAD grafting, thus showing that even with much improvement in the DES, patients with multi-vessel disease should undergo CABG preferably with as many arterial grafts as possible (however this was not demonstrated in the trials). Although many patients do not want a sternotomy, it is possible to advocate a minimally invasive direct coronary artery bypass surgery (MIDCAB), which has shown promising results in expert surgical hands ( 29 ). It is also possible to carry out hybrid procedures with IMA to LAD and DES in right or the circumflex coronary arteries, as indicated. This will require better cooperation between the surgeons as well as the interventionist, although this has not been true in the past. However, with the advent of transcatheter aortic valve replacement (TAVR), there appears to be greater cooperation and more of an atmosphere of congeniality. If we take the oath as physician “The health of my patient will be my first consideration” to heart then everyone will win; the surgeon, the interventionalist, the cardiologist, and the patient ( 30 ).
