efforts to improve the outcomes of surgical coronary revascularization have taken many forms , but among the most successful have been bilateral internal mammary artery ( i m a ) and radial artery ( ra ) grafts . it has been clear for some time that saphenous vein conduits have limited life span , and that multiple i m a s improve graft patency and clinical results . recent refinements in ra preparation and management   have taken ra patencies close to i m a s , now providing surgeons with up to four excellent arterial conduits . with four arteries and liberal sequential grafting methods , most patients can benefit from all - arterial grafts . this article will review the current status of  all - arterial  coronary bypass in current clinical practice . while a right i m a to left anterior descending ( lad ) coronary bypass was among the first coronary revascularizations performed and reported in 1967 , the subject was controversial until loop and associates demonstrated clear clinical benefits in the early 1980 s . with adoption of routine ima - coronary bypass , efforts at using more i m a conduits expanded , and evolved into the techniques of sequential and bilateral i m a grafting ( also termed internal thoracic artery [ ita ] bypass ) . objective documentation of clinical benefits subsequently emerged , and all - arterial coronary bypass became an attractive surgical option for multivessel disease patients . while all - arterial bypass has become the most common coronary artery bypass graft ( cabg ) procedure in much of the world , recent assessment of us practice showed only about 4% of cabg cases involved both i m a s .   with so much information showing clear clinical benefits , an expansion in i m a use in the us should be encouraged . in the authors practice , certain principles have been useful in the transition to all - arterial coronary grafting , and subsequent sections document concepts involved with the evolution of this approach . all - arterial coronary bypass should start with multiple i m a grafts , which are the well - validated long - term conduits for coronary revascularization . single lima bypass with ra s constructed as t - grafts probably do not substitute prognostically for multiple i m a s . for some time , the authors have been performing multiple i m a bypasses in 75 - 80% of multivessel patients , including valve / cabg cases . performing bilateral i m a grafts is more time - consuming and technically demanding than saphenous vein procedures . one optimization factor for bilateral i m a s has been liberal use of right i m a ( rima ) to lad grafts ( figure 1a ) . see text for details . in the authors series , rima to lad procedures ( figure 1a ) historic concerns regarding sternal re - entry with intact rima s traversing the midline have been dispelled by covering the graft with the thymic fat pad at the conclusion of the procedure , along with knowledge that only 4 - 5% of these patients required re - operation after 20-years . after placing the rima to the lad , the left i m a ( lima ) usually was used for single or sequential grafting of the circumflex coronary artery ( ccx ) system . the 1a approach optimized patency advantages of multiple i m a grafting , since both grafts have early patency rates of close to 100% in this configuration [ 1 , 13 ] . alternative configuration b , used in 1/3rd of the multivessel disease patients , involved placing the lima as a simple or sequential graft to the lad system , and anastomosing the rima to the right coronary artery ( rca ) ( figure 1b ) . this technique was applied more commonly in patients with proximal rca stenoses , in which the rima could reach the mid - rca easily . patencies and outcomes with this configuration have demonstrated equivalency to alternative a , understanding that in both approaches , i m a grafts should be placed to the largest , most important coronary vessels . although free i m a patencies have been good , free i m a grafts have been used infrequently in the authors practice , in order to simplify the procedure and to mitigate the necessity for extra anastomoses . however , if a free i m a offers solutions to address complex anatomic problems , there is no hesitation to use free grafts , usually connected proximally to the ascending aorta . one such example is anatomy warranting a sequential lima to important lad - diagonal vessels , in the setting of a large obstructed ccx system . the grafting strategy in this situation utilizes the lima for sequential lad grafting , and a free rima is placed to one or more ccx vessels ( configuration c ) . outcomes with radial artery ( ra ) grafting have been variable and controversial , possibly due to differences in preparation techniques . the brompton randomized trial   was a breakthrough in ra bypass , and for the first time , validated ra techniques with excellent late graft patency data . proper preparation of the ra was important in the brompton trial in order to optimize graft patency , which exceeded 95% at 5-years in randomly selected patients . important graft preparation methods include : vigorous distension of the entire graft ( including the area of the distal anastomosis ) with autologous heparinized whole blood to  break the arterial spasm ( after all , this vessel is an artery and is subject normally to high arterial pressures ) ; use of calcium channel blocking agents both in the distending blood and postoperatively for 6 weeks ; and grafting only to coronary vessels with 75% stenosis , in order to prevent a  string sign  from competitive flow . in the a and c configurations ( rima / lad - lima / ccx and seqlima / lad - freerima / ccx ) , the extra length of the ra facilitates revascularizing the distal rca with either simple or sequential anastomoses ( figure 1a ) .   in the b configuration , the ra is anastomosed to the ccxs system as a simple or sequential graft ( figure 1b ) . proximal ra anastomoses usually are performed to the aorta , and the conduit is used frequently for sequential coronary grafting . because of lower patencies in our early studies , rima grafts to ccx vessels through the transverse sinus are avoided , although better data have been published recently . while imaging of arterial grafts in our early series was performed with r - wave gated digital subtraction or conventional angiography , the recent development of high - resolution , gated , computed tomographic angiography ( cta ) has facilitated on - going validation of evolving surgical techniques . the ability to achieve > 95% patency for most i m a and ra configurations [ 1 , 4 ] has produced almost uniform early postoperative graft patency in current practice . in figure 2 are representative cta images of postoperative all - arterial bypass grafts in configuration a. computed tomographic angiography imaging of the most common type of all - arterial grafting configuration ( a ) in the author 's practice . the right internal mammary artery connects to the left anterior descending , the left internal mammary artery is a sequential graft to 2 circumflex marginal arteries , and the radial artery is used for the distal right coronary artery . the rima graft to the lad and a sequential lima graft to 2 ccx marginal arteries are evident . in this configuration , the ra is used for the distal rca , and because the ra is longer , it will reach to distal - most rca branches . likewise , figure 3 illustrates configuration b , in which lima - lad and rima - rca grafts are constructed . the second most common configuration with left internal mammary artery -left anterior descending , right internal mammary artery - right coronary artery , and radial artery - circumflex coronary artery grafts . in this configuration , the ra is used for simple or sequential grafting of the ccx system , and again because of conduit length , the ra is capable of reaching the distal branches of the ccx , if necessary . finally , in special cases , free i m a grafts are performed ( configuration c ) . figure 4 depicts coronary anatomy that mandated revascularization of 3 anterior wall vessels with a triple sequential lima graft , in the setting of a compromised important ccx system . in special cases , this patient needed a triple sequential left internal mammary artery graft to the left anterior descending system , so a free right internal mammary artery graft was placed to an important circumflex coronary artery marginal artery . the radial artery was placed to the distal right coronary artery , which was a previously stented infarct vessel and of tertiary importance . thus , the internal mammary artery grafts are usually reserved for the 2 most important coronary systems . therefore , the rima was constructed as a free graft to the large ccx vessel . thus , the relative size and importance of the coronary vessels and size of the viable myocardial regions are considered in configuration decisions , as well as the capabilities of individual arterial grafts in terms of length , coronary size - match , etc . however in over 75% of multivessel patients , at least 2 i m a s are used , and the lad is almost always revascularized with an i m a graft . many studies have demonstrated improved outcomes with multiple arterial grafts .   in our series , a multiple i m a approach to a mean follow up of 20-years   was associated with significant long - term reductions in death rates , non - fatal myocardial infarction , percutaneous coronary intervention ( pci ) , and redo coronary bypass ( figure 5 ) . fatal and non - fatal events over 20-years after single versus multiple internal mammary artery grafts ( modified from ref . the composite of all 4 events was reduced by an average of 19% over the first 15 years ( modified from reference 17 ) . data were adjusted with a cox model to compensate for minor differences in baseline characteristics . mi : myocardial infarction , pci : percutaneous coronary intervention , i m a : internal mammary artery , cabg : coronary artery bypass graft . at an interval of 15 years after surgery , 19% of patients having multiple i m a grafts benefited clinically , as compared to single i m a s and vein grafts . in the author s view , this number justifies performing all - arterial grafts in 75 - 80% of multi - vessel disease patients , including those having valve surgery with concomitant coronary obstruction . more recent studies in the duke databank involving larger sample sizes and longer follow up are on - going and are confirming these findings . out to over 25 years of follow up , composite outcomes seem to improve as arterial grafts increase ( figure 6 ) , although this analysis is in preliminary stages and needs more scrutiny . in the larger duke university series ( n=19,483 ) followed over 25 years , single internal mammary artery and adjunctive saphenous vein grafts were performed in 87% of coronary artery bypass surgery patients , multiple internal mammary artery grafts in 4% , and no internal mammary artery in 9% . the composite of all - cause death , non - fatal myocardial infarction , subsequent percutaneous coronary intervention , and redo coronary artery bypass surgery was the outcome variable . a small gradient in patient age existed between groups , with age in no internal mammary artery > single internal mammary artery > multiple internal mammary artery , so that further analysis , including multivariable risk adjustment , will be required . however , initial assessment reveals continually improving outcomes as arterial grafts are increased ( modified from ref . mima : multiple internal mammary artery , sima : single internal mammary artery , nima : no internal mammary artery . multiple i m a grafts seem to achieve the best results , although the magnitude of difference suggested in figure 6 may diminish after multivariable analysis is applied . lastly , ample data exist to confirm improved outcomes with ra conduits as adjunctive grafts to i m a s ( as compared to saphenous veins ) . so in summary , most studies confirm the benefits of performing more arterial grafts , and support the current trend toward all - arterial coronary bypass . meticulous surgical technique should be applied in harvesting fragile i m a and ra vessels to prevent spasm or intimal tears causing dissection . adequate flow should be confirmed before graft deployment to prevent the disastrous consequences of inserting a  bad  i m a or ra .   with experience and gentle technique , sometimes , an i m a graft can be small , and it is often helpful to cut the vessel back to an adequate diameter for better flow .   occasionally , this requires shortening the i m a considerably and then converting it to a free graft . finally , ra grafts require very precise harvesting and proper preparation ( as described above ) to prevent local dissection or graft spasm , also termed a  string sign  . first , many studies have shown higher rates of sternal infection with mima grafting in diabetics . the subject of sternal infection involves a number of complex multivariable issues , including operating room technique and others . graft skeletonization can be helpful , but another important factor is effective topical antibiotic irrigation at the end of the procedure which , in several randomized trials , reduced sternal infection rates from 2 - 3% in control groups to around 0.5% .    with such methods ( vancomycin - 1 gm and gentamicin - 80 mg in one liter of warm saline for irrigation at the conclusion of the procedure ) , it has been possible to liberally apply bilateral i m a procedures , so that diabetics can undergo routine all - arterial grafting with negligible sternal complications . bilateral i m a harvesting does increase early postoperative discomfort , and with longer cardiopulmonary bypass times , minor morbidities ( such as postoperative bleeding ) are slightly increased .    in the opinion of the authors , the trade - off of improved long - term results warrants this early morbidity , and most analyses lastly , all - arterial coronary bypass may be most appropriate for elective management of severe multi - vessel or left main coronary disease , whereas patients with acute myocardial infarction or less serious coronary obstruction probably fare better with pci . in this way , surgery and pci are becoming complementary rather than competitive , and in coming years , all - arterial coronary bypass should play an increasingly important role in the treatment of coronary artery disease .
surgical coronary bypass has evolved continually , and recent developments favor performing coronary grafts with all - arterial conduits in order to obtain better long - term graft patencies . with bilateral internal mammary artery grafts and both radial arteries , 
 four excellent arterial conduits exist for revascularization of the majority of multivessel disease patients , including those with valve disorders . using contemporary surgical techniques , 
 it is possible to obtain greater than 95% overall long - term graft patencies that translate into better outcomes , including improved survival , freedom from myocardial infarction , percutaneous coronary intervention , and redo coronary bypass . 
 two - thirds of patients receive a right internal mammary artery to the left anterior descending , a left internal mammary artery to the circumflex coronary artery system , and a radial artery to the right coronary artery using newer management techniques , early postoperative complications , including the incidence of sternal infections , are extremely uncommon , and all - arterial grafts currently are used in over 75% of multivessel patients including those with concomitant valve disease . because patencies and outcomes are so much better than with standard coronary bypass or percutaneous coronary intervention , referring physicians frequently favor all - arterial bypass as the primary therapy for patients with prognostically serious multivessel obstruction . 
 thus , all - arterial bypass could play an increasingly important role in the future treatment of severe coronary atherosclerosis .