ORIGINAL ARTICLE
Heart, Lung and Circulation (2015) 24, 200–205 1443-9506/04/$36.00 http://dx.doi.org/10.1016/j.hlc.2014.09.014
Saphenous Vein to Internal Mammary Artery End-to-end Composite Grafts for Coronary Artery Bypass. Late Follow-up Hugh S. Paterson, FRACS c*, Jay Thakkar, FRACP a,c, Karen Byth, PhD b,c, A. Robert Denniss, MD, FRACP a,c a
Department of Cardiology, Westmead Hospital, Hawkesbury Rd, Westmead, NSW Research and Education Network, Westmead Hospital, Hawkesbury Rd, Westmead Sydney Medical School, University of Sydney, NSW
b c
Received 6 August 2014; received in revised form 13 September 2014; accepted 22 September 2014; online published-ahead-of-print 30 September 2014
Background
Internal mammary artery (IMA) grafts provide equal or superior graft patency compared to other conduits. The IMA length limits extensive myocardial revascularisation with IMA grafts alone. This study aimed to determine the results of lengthening free IMAs with a short proximal segment of saphenous vein (SV) to enable more extensive myocardial revascularisation.
Methods
Patients (n = 92) who underwent end-to-end composite SV-IMA grafts were followed up through cardiology and death register databases.
Results
The mean patient age was 57.5 years and median follow up 10.9 years. There was no perioperative mortality and 10-year survival was 89.6%. Thirty-one patients (34%) underwent repeat angiography at a median of 2.8 years postoperatively. The 10-year freedom from angiography showing SV segment occlusion was 89% with a median time to angiography of 2.3 years (nine patients). The number of distal anastomoses was the only independent predictor of SV segment occlusion HR per anastomosis = 0.26 (p = 0.01). In five sequential grafts to the circumflex and right coronary systems, the IMA portion of the graft remained patent following SV segment occlusion.
Conclusions
Graft patency is improved by a greater number of coronary artery anastomoses.
Keywords
Ischaemic heart disease Coronary artery bypass surgery Internal mammary artery Saphenous vein Coronary angiography Composite graft
Introduction The benefits of a left IMA graft to the left anterior descending coronary artery (LAD) have been widely reported. The benefits of adding a right IMA graft to the non-LAD territories have also been described [1,2]. Composite IMA grafts allow more extensive myocardial revascularisation with IMAs with an associated theoretical benefit. Early and late results of endto-end (tandem) and end-to-side (T configuration) composite IMA grafts were reported by Tector et al, [3], with similar
outcomes for both. Composite tandem arterial grafts using the radial artery with inflow from the in situ right IMA have also been described with excellent short-term results [4,5]. This might seem to be an extravagant use of arterial conduit for a benefit not yet determined but it substantially increases the versatility of arterial grafting in coronary surgery. There have been no reported outcomes of composite tandem SV-IMA grafts although the use of a SV graft hood or aortic vein patch has been recommended for proximal anastomoses of free IMA grafts [6,7]. In theory, the durability of the
*Corresponding author at: 17 Reiby Rd, Hunters Hill, NSW 2110 Australia. Tel.: +61 2 98178408; fax: +61 2 98162934., Email: [email protected] © 2014 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier Inc. All rights reserved.
201
SV-IMA composite grafts
composite conduit will be limited by the occurrence of atherosclerosis in the SV segment of the composite graft and so the benefit of the arterial conduit might be lost. However, short segments of SV, particularly segments without valves, may be relatively resistant to SV graft atherosclerosis [8], and might also be readily treated by angioplasty and stenting if necessary. A composite SV-IMA graft from the aorta can revascularise the circumflex and right coronary arteries and for non-LAD double vessel disease it preserves the left IMA for later use if required. There is limited information on the incidence of development of significant LAD disease after coronary surgery for non-LAD double vessel disease [9] such that surgeons might tailor the surgery for double vessel disease to account for a later need to revascularise the LAD.
Methods All patients under the care of a single surgeon (HSP) who underwent SV-IMA end-to-end composite grafts were identified from a cardiac surgical database of prospectively collected data. Operation reports were retrieved for acquisition
of data regarding coronary artery and bypass graft quality and size. Late follow-up was obtained by cross-matching patient data against hospital and cardiology databases in western Sydney and against the New South Wales Register of Births, Deaths and Marriages which is linked to death registers in other states. This method of database follow-up has been shown to achieve over 99% follow-up accuracy [10]. The project was approved by Western Sydney Local Health District Human Research Ethics Committee.
Surgery All procedures were performed through a midline sternotomy with harvesting of IMAs by a semi-skeletonising technique [11]. The right IMA was used for the composite graft in all but six patients. The SV was harvested from the ankle through a longitudinal incision or from the upper thigh through a transverse incision. Only one patient underwent off-pump surgery. Cardiopulmonary bypass with intermittent blood cardioplegia was used in all others. When the use of a SV-IMA composite graft was planned preoperatively, the free composite graft was prepared synchronously with the institution of cardiopulmonary bypass.
Figure 1 The 4 most common graft configurations are shown along with the number of angiograms performed in each group, identifying numbers with all grafts patent, occlusion of the proximal segment of the SV-IMA graft, and the total number of angiograms. The 2 configurations on the right represent group 3 as described in the methods, where the right IMA was too short to complete a bilateral IMA Y graft configuration. RCA = right coronary artery, LAD = left anterior descending artery, LIMA = left IMA.
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H.S. Paterson et al.
When bilateral IMA grafting was employed, the requirement for saphenous vein use was identified when it was seen that the right IMA was of insufficient length to reach the proximal inflow target after completion of the distal anastomoses. The vein was then harvested and the SV-IMA anastomosis performed. The end-to-end anastomosis was constructed after bevelling the SV and IMA ends to accommodate the disparity in conduit diameters. The proximal end of the SV segment was anastomosed to the proximal end of the IMA. For the coronary anastomoses, end-to-side anastomoses were constructed in parallel and side-to-side anastomoses were perpendicular [11]. The median length of SV used after completion of the proximal anastomosis was 5 cm (range: 2 – 15 cm). The most frequently used graft configurations and angiography results are shown in Fig. 1 and summarised in Table 1. The series is comprised largely of three specific groups of patients. The largest group (n = 55) had non-LAD double vessel disease and underwent planned sequential grafting with a composite SV-IMA graft from the ascending aorta. The second group (n = 13) had triple vessel disease but the grafted free wall coronary artery was relatively high and so the left-sided vessels were grafted with a bilateral IMA Y graft using a short segment of the right IMA, and then the right coronary system was grafted with the residual right IMA as a SV-IMA composite graft. In the third group (n = 16) there was an intention to perform total arterial grafting with a bilateral IMA Y graft but the operative plan changed when inadequate right IMA length was identified. A segment of SV was harvested and anastomosed to the proximal end of the right IMA and then proximally, either end-to-side to the left IMA (n = 11) or to the aorta (n = 5). Four patients underwent redo coronary bypass surgery and concomitant procedures were performed in 11 patients (left ventricular reconstruction (3), mitral valve replacement (2), atrial radio-frequency ablation (1), carotid endarterectomy (4) and partial lung resection (1)). Post-discharge angiography was performed for investigation of symptoms or evidence of myocardial ischaemia, at the discretion of the referring cardiologists.
Table 1 Summary of graft configurations (Figure 4). Graft configuration
Total n = 92
Composite IMA to OM and to right system (n = 76) From aorta only From aorta with separate LAD graft From in situ left IMA From free IMA from aorta to LAD Composite IMA to right system (with BIMA Y to LAD & OM) Other
55 5 11
Definitions Preoperative and operative variable definitions were consistent with those of the Society of Thoracic Surgeons database. Thirty-two potential risk factors were considered in the statistical analysis of predictors of the outcomes of late death and of re-angiography showing SV segment occlusion. For the statistical analyses, grafts were classified as occluded or patent, with stenoses greater than 70% classified as occluded. Kaplan-Meier survival curves were used to illustrate the survival distributions of interest. Log rank tests were used to assess the association between a survival distribution and a categorical risk factor. Cox proportional hazards models were used to assess associations with continuous risk factors and the hazard ratio with its 95% confidence interval (95%CI) used to quantify this association. The statistical package SPSS Version 21 was used to analyse the data. Two-tailed tests with a significance level of 5% were used throughout.
Results Ninety-two patients who underwent coronary bypass grafting with a composite end-to-end SV-IMA graft between 1995 and 2008 were identified and represented 3% of the total coronary surgery procedures during that time. The mean age was 57.5 years (SD 9.0, range 27 – 81 years). The major preoperative risks and operative variables are listed in Table 2. There were no perioperative deaths or episodes of myocardial infarction.
Table 2 Major preoperative and operative risks. Preoperative major risks
%
Female
13
Unstable angina
32
LM stenosis
7
Symptom class IV Diabetes
42 33
LVEF 50% stenosis).
205
SV-IMA composite grafts
occlusion suggested a decreasing incidence over time, which is more consistent with the late outcomes of arterial grafts than SV grafts. The Kaplan-Meier estimate of survival was comparable to a similar cohort of patients who underwent arterial graft coronary surgery, albeit for more severe coronary disease [11]. For the patients with non-LAD double vessel disease, Royce et al [14] reported the use of a composite radial artery T graft from the left IMA with anastomosis of the IMA to the LAD with a less than 50% stenosis. They reported that the severity of the LAD stenosis below which the incidence of IMA occlusion seen at late angiography significantly increased, was 40%, although the majority still remained open. The argument in favour of this configuration relates to the likelihood of progression of the native LAD disease. In our series, the incidence of presentation with progression of LAD disease might be a little lower than expected [9] but is such that the first operation for these patients should be considered to be definitive and durable. When proximal occlusion of the sequential SV-IMA graft to the two non-LAD territories occurred, the IMA portion of the graft from the first coronary anastomosis remained open. This provided the option for angioplasty to the most suitable vessel connected to the IMA coronary-coronary graft segment, which can restore good myocardial perfusion to both territories. In the group of patients (n = 16) who had planned revascularisation solely with bilateral IMA grafts, only two patients underwent repeat angiography and both showed all grafts to be patent. It appears that either option for addressing a short right IMA in this situation is acceptable. The patency of the SV-IMA grafts improved with an increasing number of distal anastomoses from the composite graft, although this was largely driven by a higher occlusion rate in grafts to only one vessel. The incidence of presentation with occlusion of a graft solely to the right coronary territory was greater than that of the terminal segment of sequential composite grafts from the circumflex to the right system (4 of 13 versus 2 of 76), but this did not reach significance as an independent predictor of presentation with graft occlusion in this small series.
Limitations This study is a database follow-up of a small cohort of patients who underwent coronary bypass surgery which included redo and concomitant procedures. The bypass graft configurations used were also heterogeneous. The absolute number of identified SV-IMA occlusions was small and graft patency in the 61 patients who did not undergo angiography is unknown. Only limited comparative data exist in the form for a similar cohort of patients with more extensive coronary artery disease who underwent bilateral IMA composite grafting under the care of the same surgeon.
Conclusions Patency of end-to-end SV-IMA anastomoses in composite grafts is improved by a greater number of coronary artery anastomoses. Presentation with atheromatous degeneration in patent proximal SV segments of composite grafts was uncommon. The incidence of presentation with new LAD disease after coronary surgery for non LAD disease is low.
Acknowledgements No financial support or conflicts of interest.
References [1] Lytle BW, Blackstone EH, Loop FD, Houghtaling PL, Arnold JH, Akhrass R, et al. Two internal thoracic artery grafts are better than one. J Thorac Cardiovasc Surg 1999 May;117(5):855–72. [2] Tatoulis J, Buxton BF, Fuller JA. The right internal thoracic artery: the forgotten conduit–5,766 patients and 991 angiograms. Ann Thorac Surg 2011 Jul;92(1):9–15. [3] Tector AJ, McDonald ML, Kress DC, Downey FX, Schmahl TM. Purely internal thoracic artery grafts: outcomes. Ann Thorac Surg 2001 Aug;72 (2):450–5. [4] Fukui S, Fukuda H, Toda K, Yoshitatsu M, Funatsu T, Masai T, et al. Remodeling of the radial artery anastomosed to the internal thoracic artery as a composite straight graft. J Thorac Cardiovasc Surg 2007 Nov;134(5):1136–42. [5] Nakajima H, Kobayashi J, Tagusari O, Niwaya K, Funatsu T, Brik A, et al. Graft design strategies with optimum antegrade bypass flow in total arterial off-pump coronary artery bypass. Eur J Cardiothorac Surg 2007 Feb;31(2):276–82. [6] Loop FD, Lytle BW, Cosgrove DM, Golding LA, Taylor PC, Stewart RW. Free (aorta-coronary) internal mammary artery graft. Late results. J Thorac Cardiovasc Surg 1986 Nov;92(5):827–31. [7] Shin H, Yozu R, Hashizume K, Iino Y, Enoki C, Koizumi K, et al. Free right internal thoracic artery as a second arterial conduit: modification of proximal anastomosis for improvement of graft patency. Ann Thorac Cardiovasc Surg 2001 Jun;7(3):155–8. [8] Mills NL, Everson CT. Vein graft failure. Curr Opin Cardiol 1995 Nov;10 (6):562–8. [9] Hayward PA, Zhu YY, Nguyen TT, Hare DL, Buxton BF. Should all moderate coronary lesions be grafted during primary coronary bypass surgery? An analysis of progression of native vessel disease during a randomized trial of conduits. J Thorac Cardiovasc Surg 2013 Jan;145 (1):140–8. [10] Mayorchak Y, Paterson H, Ryan JB, Byth K, Robinson LM, Kovoor P, et al. Mammary artery to saphenous vein composite T grafts for coronary artery bypass: late follow-up. J Cardiovasc Surg (Torino) 2013 Aug;54 (4):531–6. [11] Paterson HS, Naidoo R, Byth K, Chen C, Denniss AR. Full myocardial revascularization with bilateral internal mammary artery Y grafts. Ann Cardiothorac Surg 2013 Jul;2(4):444–52. [12] Dimitrova KR, Hoffman DM, Geller CM, Dincheva G, Ko W, Tranbaugh RF. Arterial grafts protect the native coronary vessels from atherosclerotic disease progression. Ann Thorac Surg 2012 Aug;94(2):475–81. [13] Glineur D, D’hoore W, de Kerchove L, Noirhomme P, Price J, Hanet C, et al. Angiographic predictors of 3-year patency of bypass grafts implanted on the right coronary artery system: a prospective randomized comparison of gastroepiploic artery, saphenous vein, and right internal thoracic artery grafts. J Thorac Cardiovasc Surg 2011 Nov;142(5):980–8. [14] Royse AG, Royse CF, Tatoulis J, Grigg LE, Shah P, Hunt D, et al. Postoperative radial artery angiography for coronary artery bypass surgery. Eur J Cardiothorac Surg 2000 Mar;17(3):294–304.
Heart, Lung and Circulation (2015) 24, 200–205 1443-9506/04/$36.00 http://dx.doi.org/10.1016/j.hlc.2014.09.014
Saphenous Vein to Internal Mammary Artery End-to-end Composite Grafts for Coronary Artery Bypass. Late Follow-up Hugh S. Paterson, FRACS c*, Jay Thakkar, FRACP a,c, Karen Byth, PhD b,c, A. Robert Denniss, MD, FRACP a,c a
Department of Cardiology, Westmead Hospital, Hawkesbury Rd, Westmead, NSW Research and Education Network, Westmead Hospital, Hawkesbury Rd, Westmead Sydney Medical School, University of Sydney, NSW
b c
Received 6 August 2014; received in revised form 13 September 2014; accepted 22 September 2014; online published-ahead-of-print 30 September 2014
Background
Internal mammary artery (IMA) grafts provide equal or superior graft patency compared to other conduits. The IMA length limits extensive myocardial revascularisation with IMA grafts alone. This study aimed to determine the results of lengthening free IMAs with a short proximal segment of saphenous vein (SV) to enable more extensive myocardial revascularisation.
Methods
Patients (n = 92) who underwent end-to-end composite SV-IMA grafts were followed up through cardiology and death register databases.
Results
The mean patient age was 57.5 years and median follow up 10.9 years. There was no perioperative mortality and 10-year survival was 89.6%. Thirty-one patients (34%) underwent repeat angiography at a median of 2.8 years postoperatively. The 10-year freedom from angiography showing SV segment occlusion was 89% with a median time to angiography of 2.3 years (nine patients). The number of distal anastomoses was the only independent predictor of SV segment occlusion HR per anastomosis = 0.26 (p = 0.01). In five sequential grafts to the circumflex and right coronary systems, the IMA portion of the graft remained patent following SV segment occlusion.
Conclusions
Graft patency is improved by a greater number of coronary artery anastomoses.
Keywords
Ischaemic heart disease Coronary artery bypass surgery Internal mammary artery Saphenous vein Coronary angiography Composite graft
Introduction The benefits of a left IMA graft to the left anterior descending coronary artery (LAD) have been widely reported. The benefits of adding a right IMA graft to the non-LAD territories have also been described [1,2]. Composite IMA grafts allow more extensive myocardial revascularisation with IMAs with an associated theoretical benefit. Early and late results of endto-end (tandem) and end-to-side (T configuration) composite IMA grafts were reported by Tector et al, [3], with similar
outcomes for both. Composite tandem arterial grafts using the radial artery with inflow from the in situ right IMA have also been described with excellent short-term results [4,5]. This might seem to be an extravagant use of arterial conduit for a benefit not yet determined but it substantially increases the versatility of arterial grafting in coronary surgery. There have been no reported outcomes of composite tandem SV-IMA grafts although the use of a SV graft hood or aortic vein patch has been recommended for proximal anastomoses of free IMA grafts [6,7]. In theory, the durability of the
*Corresponding author at: 17 Reiby Rd, Hunters Hill, NSW 2110 Australia. Tel.: +61 2 98178408; fax: +61 2 98162934., Email: [email protected] © 2014 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier Inc. All rights reserved.
201
SV-IMA composite grafts
composite conduit will be limited by the occurrence of atherosclerosis in the SV segment of the composite graft and so the benefit of the arterial conduit might be lost. However, short segments of SV, particularly segments without valves, may be relatively resistant to SV graft atherosclerosis [8], and might also be readily treated by angioplasty and stenting if necessary. A composite SV-IMA graft from the aorta can revascularise the circumflex and right coronary arteries and for non-LAD double vessel disease it preserves the left IMA for later use if required. There is limited information on the incidence of development of significant LAD disease after coronary surgery for non-LAD double vessel disease [9] such that surgeons might tailor the surgery for double vessel disease to account for a later need to revascularise the LAD.
Methods All patients under the care of a single surgeon (HSP) who underwent SV-IMA end-to-end composite grafts were identified from a cardiac surgical database of prospectively collected data. Operation reports were retrieved for acquisition
of data regarding coronary artery and bypass graft quality and size. Late follow-up was obtained by cross-matching patient data against hospital and cardiology databases in western Sydney and against the New South Wales Register of Births, Deaths and Marriages which is linked to death registers in other states. This method of database follow-up has been shown to achieve over 99% follow-up accuracy [10]. The project was approved by Western Sydney Local Health District Human Research Ethics Committee.
Surgery All procedures were performed through a midline sternotomy with harvesting of IMAs by a semi-skeletonising technique [11]. The right IMA was used for the composite graft in all but six patients. The SV was harvested from the ankle through a longitudinal incision or from the upper thigh through a transverse incision. Only one patient underwent off-pump surgery. Cardiopulmonary bypass with intermittent blood cardioplegia was used in all others. When the use of a SV-IMA composite graft was planned preoperatively, the free composite graft was prepared synchronously with the institution of cardiopulmonary bypass.
Figure 1 The 4 most common graft configurations are shown along with the number of angiograms performed in each group, identifying numbers with all grafts patent, occlusion of the proximal segment of the SV-IMA graft, and the total number of angiograms. The 2 configurations on the right represent group 3 as described in the methods, where the right IMA was too short to complete a bilateral IMA Y graft configuration. RCA = right coronary artery, LAD = left anterior descending artery, LIMA = left IMA.
202
H.S. Paterson et al.
When bilateral IMA grafting was employed, the requirement for saphenous vein use was identified when it was seen that the right IMA was of insufficient length to reach the proximal inflow target after completion of the distal anastomoses. The vein was then harvested and the SV-IMA anastomosis performed. The end-to-end anastomosis was constructed after bevelling the SV and IMA ends to accommodate the disparity in conduit diameters. The proximal end of the SV segment was anastomosed to the proximal end of the IMA. For the coronary anastomoses, end-to-side anastomoses were constructed in parallel and side-to-side anastomoses were perpendicular [11]. The median length of SV used after completion of the proximal anastomosis was 5 cm (range: 2 – 15 cm). The most frequently used graft configurations and angiography results are shown in Fig. 1 and summarised in Table 1. The series is comprised largely of three specific groups of patients. The largest group (n = 55) had non-LAD double vessel disease and underwent planned sequential grafting with a composite SV-IMA graft from the ascending aorta. The second group (n = 13) had triple vessel disease but the grafted free wall coronary artery was relatively high and so the left-sided vessels were grafted with a bilateral IMA Y graft using a short segment of the right IMA, and then the right coronary system was grafted with the residual right IMA as a SV-IMA composite graft. In the third group (n = 16) there was an intention to perform total arterial grafting with a bilateral IMA Y graft but the operative plan changed when inadequate right IMA length was identified. A segment of SV was harvested and anastomosed to the proximal end of the right IMA and then proximally, either end-to-side to the left IMA (n = 11) or to the aorta (n = 5). Four patients underwent redo coronary bypass surgery and concomitant procedures were performed in 11 patients (left ventricular reconstruction (3), mitral valve replacement (2), atrial radio-frequency ablation (1), carotid endarterectomy (4) and partial lung resection (1)). Post-discharge angiography was performed for investigation of symptoms or evidence of myocardial ischaemia, at the discretion of the referring cardiologists.
Table 1 Summary of graft configurations (Figure 4). Graft configuration
Total n = 92
Composite IMA to OM and to right system (n = 76) From aorta only From aorta with separate LAD graft From in situ left IMA From free IMA from aorta to LAD Composite IMA to right system (with BIMA Y to LAD & OM) Other
55 5 11
Definitions Preoperative and operative variable definitions were consistent with those of the Society of Thoracic Surgeons database. Thirty-two potential risk factors were considered in the statistical analysis of predictors of the outcomes of late death and of re-angiography showing SV segment occlusion. For the statistical analyses, grafts were classified as occluded or patent, with stenoses greater than 70% classified as occluded. Kaplan-Meier survival curves were used to illustrate the survival distributions of interest. Log rank tests were used to assess the association between a survival distribution and a categorical risk factor. Cox proportional hazards models were used to assess associations with continuous risk factors and the hazard ratio with its 95% confidence interval (95%CI) used to quantify this association. The statistical package SPSS Version 21 was used to analyse the data. Two-tailed tests with a significance level of 5% were used throughout.
Results Ninety-two patients who underwent coronary bypass grafting with a composite end-to-end SV-IMA graft between 1995 and 2008 were identified and represented 3% of the total coronary surgery procedures during that time. The mean age was 57.5 years (SD 9.0, range 27 – 81 years). The major preoperative risks and operative variables are listed in Table 2. There were no perioperative deaths or episodes of myocardial infarction.
Table 2 Major preoperative and operative risks. Preoperative major risks
%
Female
13
Unstable angina
32
LM stenosis
7
Symptom class IV Diabetes
42 33
LVEF 50% stenosis).
205
SV-IMA composite grafts
occlusion suggested a decreasing incidence over time, which is more consistent with the late outcomes of arterial grafts than SV grafts. The Kaplan-Meier estimate of survival was comparable to a similar cohort of patients who underwent arterial graft coronary surgery, albeit for more severe coronary disease [11]. For the patients with non-LAD double vessel disease, Royce et al [14] reported the use of a composite radial artery T graft from the left IMA with anastomosis of the IMA to the LAD with a less than 50% stenosis. They reported that the severity of the LAD stenosis below which the incidence of IMA occlusion seen at late angiography significantly increased, was 40%, although the majority still remained open. The argument in favour of this configuration relates to the likelihood of progression of the native LAD disease. In our series, the incidence of presentation with progression of LAD disease might be a little lower than expected [9] but is such that the first operation for these patients should be considered to be definitive and durable. When proximal occlusion of the sequential SV-IMA graft to the two non-LAD territories occurred, the IMA portion of the graft from the first coronary anastomosis remained open. This provided the option for angioplasty to the most suitable vessel connected to the IMA coronary-coronary graft segment, which can restore good myocardial perfusion to both territories. In the group of patients (n = 16) who had planned revascularisation solely with bilateral IMA grafts, only two patients underwent repeat angiography and both showed all grafts to be patent. It appears that either option for addressing a short right IMA in this situation is acceptable. The patency of the SV-IMA grafts improved with an increasing number of distal anastomoses from the composite graft, although this was largely driven by a higher occlusion rate in grafts to only one vessel. The incidence of presentation with occlusion of a graft solely to the right coronary territory was greater than that of the terminal segment of sequential composite grafts from the circumflex to the right system (4 of 13 versus 2 of 76), but this did not reach significance as an independent predictor of presentation with graft occlusion in this small series.
Limitations This study is a database follow-up of a small cohort of patients who underwent coronary bypass surgery which included redo and concomitant procedures. The bypass graft configurations used were also heterogeneous. The absolute number of identified SV-IMA occlusions was small and graft patency in the 61 patients who did not undergo angiography is unknown. Only limited comparative data exist in the form for a similar cohort of patients with more extensive coronary artery disease who underwent bilateral IMA composite grafting under the care of the same surgeon.
Conclusions Patency of end-to-end SV-IMA anastomoses in composite grafts is improved by a greater number of coronary artery anastomoses. Presentation with atheromatous degeneration in patent proximal SV segments of composite grafts was uncommon. The incidence of presentation with new LAD disease after coronary surgery for non LAD disease is low.
Acknowledgements No financial support or conflicts of interest.
References [1] Lytle BW, Blackstone EH, Loop FD, Houghtaling PL, Arnold JH, Akhrass R, et al. Two internal thoracic artery grafts are better than one. J Thorac Cardiovasc Surg 1999 May;117(5):855–72. [2] Tatoulis J, Buxton BF, Fuller JA. The right internal thoracic artery: the forgotten conduit–5,766 patients and 991 angiograms. Ann Thorac Surg 2011 Jul;92(1):9–15. [3] Tector AJ, McDonald ML, Kress DC, Downey FX, Schmahl TM. Purely internal thoracic artery grafts: outcomes. Ann Thorac Surg 2001 Aug;72 (2):450–5. [4] Fukui S, Fukuda H, Toda K, Yoshitatsu M, Funatsu T, Masai T, et al. Remodeling of the radial artery anastomosed to the internal thoracic artery as a composite straight graft. J Thorac Cardiovasc Surg 2007 Nov;134(5):1136–42. [5] Nakajima H, Kobayashi J, Tagusari O, Niwaya K, Funatsu T, Brik A, et al. Graft design strategies with optimum antegrade bypass flow in total arterial off-pump coronary artery bypass. Eur J Cardiothorac Surg 2007 Feb;31(2):276–82. [6] Loop FD, Lytle BW, Cosgrove DM, Golding LA, Taylor PC, Stewart RW. Free (aorta-coronary) internal mammary artery graft. Late results. J Thorac Cardiovasc Surg 1986 Nov;92(5):827–31. [7] Shin H, Yozu R, Hashizume K, Iino Y, Enoki C, Koizumi K, et al. Free right internal thoracic artery as a second arterial conduit: modification of proximal anastomosis for improvement of graft patency. Ann Thorac Cardiovasc Surg 2001 Jun;7(3):155–8. [8] Mills NL, Everson CT. Vein graft failure. Curr Opin Cardiol 1995 Nov;10 (6):562–8. [9] Hayward PA, Zhu YY, Nguyen TT, Hare DL, Buxton BF. Should all moderate coronary lesions be grafted during primary coronary bypass surgery? An analysis of progression of native vessel disease during a randomized trial of conduits. J Thorac Cardiovasc Surg 2013 Jan;145 (1):140–8. [10] Mayorchak Y, Paterson H, Ryan JB, Byth K, Robinson LM, Kovoor P, et al. Mammary artery to saphenous vein composite T grafts for coronary artery bypass: late follow-up. J Cardiovasc Surg (Torino) 2013 Aug;54 (4):531–6. [11] Paterson HS, Naidoo R, Byth K, Chen C, Denniss AR. Full myocardial revascularization with bilateral internal mammary artery Y grafts. Ann Cardiothorac Surg 2013 Jul;2(4):444–52. [12] Dimitrova KR, Hoffman DM, Geller CM, Dincheva G, Ko W, Tranbaugh RF. Arterial grafts protect the native coronary vessels from atherosclerotic disease progression. Ann Thorac Surg 2012 Aug;94(2):475–81. [13] Glineur D, D’hoore W, de Kerchove L, Noirhomme P, Price J, Hanet C, et al. Angiographic predictors of 3-year patency of bypass grafts implanted on the right coronary artery system: a prospective randomized comparison of gastroepiploic artery, saphenous vein, and right internal thoracic artery grafts. J Thorac Cardiovasc Surg 2011 Nov;142(5):980–8. [14] Royse AG, Royse CF, Tatoulis J, Grigg LE, Shah P, Hunt D, et al. Postoperative radial artery angiography for coronary artery bypass surgery. Eur J Cardiothorac Surg 2000 Mar;17(3):294–304.
