Asian Cardiovasc Thorac Ann 2005;13:161-166
© 2005 Asia Publishing EXchange Ltd
Sequential Radial Artery Grafting Three-Vessel Coronary Artery Disease
Esat Ak
nc, MD,
Vedat Erentug, MD,
Kemal Uzun, MD,
Adil Polat, MD,
Deniz Göksedef, MD,
Cevat Yakut, MD
Ko
uyolu Heart and Research Hospital, Istanbul, Turkey
For reprint information contact: Vedat Erentug, MD Tel: 90 216 326 6969 Fax: 90 216 339 0441 Email: drvedat2002{at}yahoo.com, Ulus Vadi Konutlari A1/9, Ortakoy, 80840 Besiktas, stanbul, Turkey
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ABSTRACT
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Our objective was to compare the results of revascularization by sequential radial artery (RA) grafting with a left anterior descending left internal mammary artery (LIMA)-RA t-composite grafting technique. Patients were grouped as those with proximal anastomoses performed on the ascending aorta (Group A; n = 38), and those with proximal anastomoses performed on the LIMA as t-grafts (Group T; n = 13). Neither of the two groups revealed any mortality. The average number of grafts was lower in Group T (2.23 ± 0.43 in group T and 2.85 ± 0.69 in group A, p < 0.05). The results of the control coronary artery angiographies were superior in Group A. The patency rate of the RA grafts was 96.8% in Group A. Of the 20 distal anastomoses performed with RA grafts in 8 patients from Group T, nine (45%) were found to be patent. The patency rates of RA grafts with sequential distal anastomoses were found to be better when the proximal anastomosis was performed on the ascending aorta rather than on the LIMA. In conclusion, sequential distal anastomosis of RA grafts seem to be safe and effective when proximal anastomoses are performed on the ascending aorta.
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INTRODUCTION
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Radial artery (RA) was first used in coronary artery bypass grafting (CABG) as an alternative graft in 1973 by Carpentier et al.1 Two years later, Carpentier abandoned RA grafting due to serious diffuse stenosis in 35% of denervated RA grafts. Carpentier et al revised RA grafting again in 1989, 15 years after RA grafts were found patent in control angiographies. Subsequently, in the 1990s, Acar et al2,3 recommenced RA grafting. Acar et al3 and Calafiore et al4 reported superior late-term patency rates for RA grafts compared to saphenous vein grafts of 93.5% and 94.1%, respectively.
The lower mortality and morbidity rates, the shorter hospital stay and the decreased reoperation rate of complete arterial revascularization also provides an increase in both quality of life and survival.5 With the superior long-term results of arterial grafts over venous grafts, to prolong long-term survival, to decrease the need for reinterventions and to decrease the patients’ complaints, complete arterial revascularization has become the objective of CABG surgery.6–8 Historically, three or more grafts were used for complete arterial revascularization of three-vessel coronary artery disease patients. However, this approach discouraged widespread use of complete arterial revascularization due to the time-consuming and traumatic nature of the procedure.8
Tector et al9 presented their t-graft technique for complete arterial revascularization in 1994. In this technique, left internal mammary artery (LIMA) was anastomosed to the coronary arteries of the anterior wall, and the free graft right internal mammary artery (RIMA) was anastomosed to the coronary arteries of the inferior and posterolateral walls sequentially with its proximal anastomosis on the LIMA. T-grafts with LIMA and RA were reported later.3,4,10 Thus, complete arterial revascularization could be achieved with two conduits in three-vessel coronary artery disease.
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PATIENTS AND METHODS
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PATIENT POPULATION
Fifty-one patients were operated on using sequential distal anastomoses of the RA graft at the Kouyolu Heart and Research Hospital between June 1999 and December 2002. Indications for the use of the RA graft were relatively young age, stenosis being 70% or more and the flow in the distal segment of the target vessel after the stenosis being angiographically high. Patients undergoing proximal anastomoses of the RA grafts on the ascending aorta were grouped in Group A (n = 38) and patients undergoing proximal anastomoses on the LIMA as t-graft were grouped in Group T (n = 13). The two groups were compared with respect to preoperative demographic characteristics and risk profiles (Table 1
). The average age of patients in Group A was 50.5 ± 9.1 years (range 29–68 years) and in Group T 47.5 ± 8.2 years (range 37–66 years). None of the patients revealed any associated morbidity, such as chronic renal failure, carotid artery stenosis, previous cardiac operation or additional cardiac pathology. Two patients had a previous percutaneous transluminal coronary angioplasty/stenting procedure; these belonged to Group A. All of the patients were operated electively. The two groups were comparable with respect to average age, the intensity of angina pectoris, the presence of diabetes mellitus, hypertension, hypercholesterolemia, left main coronary arterial disease, left ventricular dysfunction and previous myocardial infarction. No statistically significant difference was noted between the two groups (Table 1).
SURGICAL TECHNIQUE
Sequential arterial grafting was planned in patients at relatively younger ages, with 70% or more stenosis on the target vessel of which the distal diameter was about 1.5 mm or more [except for the left anterior descending (LAD) artery]. Allen’s test was performed on the nondominant arm. The nondominant arm was left in all cases and Allen’s test was found negative in all. We did not perform any bilateral RA harvesting.
All patients received the same analgesic premedication, induction and maintenance protocol. Median sternotomy was used in all cases. While a surgeon was harvesting the LIMA, a second surgeon performed the RA harvesting from the nondominant arm. LIMA was harvested with its pedicle proximally up to the level of the subclavian vein and distally to the level of its bifurcation to the superior epigastric artery and the musculophrenic artery. Fascia and the surrounding tissues were dissected with electrocautery at low voltage and the side branches were ligated with hemoclips. RA was harvested with vena communicans and the surrounding fatty tissue aside using hemoclips to ligate the side branches. After the RA was procured, a solution prepared by adding 60 mg of papaverine and 5 mg of verapamil into 250 mL of isotonic NaCl solution at room temperature was introduced into its proximal end via a 22G angiocath with low pressure for both dilation and bleeding control purposes. Then, the RA graft was put into the same solution until use. The incision on the arm was closed after neutralization of heparin.
Arterial cannulation on the ascending aorta and two-stage venous cannulation from the right atrium were performed. Heparin was administered at a dose of 3 mg·kg–1. All patients were operated on pump. A moderate degree of systemic hypothermia (28–32°C) was used. Venting and antegrade cardioplegia cannulation on the ascending aorta and retrograde cardioplegia cannulation through the right atrium was performed. The heart was arrested in an antegrade fashion, after the aorta was clamped, with 10 mL·kg–1 body weight isothermic blood cardioplegia with potassium. Myocardial protection was maintained with continuous retrograde cardioplegia delivery.
If necessary, other additional stenotic vessels exempt from the study criteria were revascularized with saphenous vein grafts. An RA distal anastomosis was performed afterwards. Sequential anastomoses were performed starting from the posterolateral branch using an end-to-side technique and continued sequentially to the optus marginalis and diagonal branches using a side-to-side technique either diamond-shaped or longitudinally. RA was anastomosed on its volar side facing the myocardium, which provided good exposure to its dorsal side from which most of the side branches originate. Therefore, any probable bleeding from the side branches after completion of the anastomoses could be easily controlled. Finally, LIMA anastomosis to the LAD artery was performed. All distal anastomoses were performed using either 7/0 or 8/0 polypropylene sutures. Then, a saphenous vein proximal anastomosis was performed if necessary. Radial artery was anastomosed to the ascending aorta if its length permitted, otherwise a t-graft configuration on the anterior face of LIMA was preferred. In the case of a proximal anastomosis on the ascending aorta, a 6/0 suture was used; a 7/0 suture was used on the LIMA. All proximal anastomoses were performed with the aorta cross clamped. Parallel to the arterial flow dynamics, the RA proximal end was used for proximal, and its distal end for the distal anastomoses. All operations were performed in our hospital by five different operating teams in a randomized fashion. The operating teams discussed the indications for the operations and the operative procedures in a common forum.
OPERATIVE CHARACTERISTICS
A comparison of the operations in both groups (Table 2) showed some advantages for the t-graft technique. The number of grafts per single patient was found to be statistically significantly different between the two groups (2.23 ± 0.43 in group T and 2.85 ± 0.69 in group A, p < 0.05). A single RA graft could be used for 2.08 ± 0.70 distal anastomoses in Group A and for 2.54 ± 0.71 anastomoses in Group T ( p < 0.05). In Group A, none of the patients could be completely revascularized using the LIMA and the RA grafts, whereas this was possible in 46.15% of cases in Group T ( p < 0.05).
PHARMACOLOGIC PROTOCOL
For a vasodilatory effect, diltiazem infusion at a dose of 1 µg·min–1·kg–1 body weight was started after the administration of anesthesia. This infusion was maintained at the same dosage in the intensive care unit for 48 hours. After extubation, 180 mg of diltiazem in 3 divided doses were given orally.
STATISTICAL METHODS
Data are presented as average ± standard deviation, and analyses were performed using the t-test, chi-square test and Fisher’s exact test where applicable. p-Values < 0.05 were considered significant (SPSS 10.0, SPSS Inc., Chicago, IL, USA).
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RESULTS
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During the hospital stay, no mortality or cardiovascular morbidity were noted in either group. The need for mechanical support with an intra-aortic balloon counterpulsation and an emergency operation for bleeding or low cardiac output was not required. No significant differences were noted with respect to the total hospital stay, the amount of drainage, incidences of low cardiac output, perioperative myocardial infarction, arrhythmia or infection; however, the extubation time was longer in Group A (Table 3).
Twenty seven patients in Group A were followed up and, of these, 15 patients agreed to have control coronary artery angiography. Of the 12 patients followed up in Group T, 8 of them agreed to undergo control coronary artery angiography. No patients received thallium scintigraphy. The mean periods between the operation and the control angiographic investigation were 13 ± 8.5 months (range 2–19 months) and 9 ± 5.1 months (range 1–16 months) in Group A and Group T, respectively. The anginal status of the patients is shown in Table 4. Angiographic analysis was based on the distal anastomoses being functional and each single distal anastomosis was analyzed separately. For example, for a RA graft occluded proximally, each distal anastomosis was accepted as nonfunctional. A LIMA anastomosis to the LAD artery was patent in each patient. The sequential distal anastomoses of the RA graft in Group A revealed a 96.8% patency rate in Group A and 45% in Group T and the difference was found to be statistically significant ( p = 0.001). No RA spasm or stenosis was noted in Group T, but did occur in 1 patient in Group A (Table 5).
Analysis of postoperative angina was done on the group of patients who agreed to have a control angiography. In both groups, most of the patients were free of angina. Persistance of preoperative angina postoperatively was noted in 3 patients (20%) in Group A and in 2 patients (25%) in Group T.
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DISCUSSION
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Arterial grafts are favored for their superior mid and long-term patency rates. The availability of sufficient graft length is the main limitation to this procedure. Previously, three or more grafts were used for a complete revascularization.
Another advantage of the composite grafts is the absence of, or the low number of proximal anastomoses on the aorta. Severe atherosclerosis of the ascending aorta is associated with increased mortality and morbidity due to the risk of perioperative atheroembolism. The incidence of significant atheromatous disease of the ascending aorta among patients who have had a cardiac operation varies between 14% and 29%.10 Blauth et al12 found a strong association between atheroembolism and atherosclerosis of the ascending aorta in an autopsy study of 221 patients who died after a cardiac operation. In patients receiving a composite graft of LIMA and RA grafts, a lower incidence of atheroembolism-associated mortality and morbidity may well be expected. Yilmaz et al5 reported no cerebrovascular accident (CVA) in 127 patients and Tector et al9 reported 3 (1.7%) CVAs in 287 patients.
Using techniques of sequential and/or composite grafting, a single graft may be suitable for more than one anastomosis. The advantages of these techniques are the low numbers or absence of proximal anastomoses and the lower number of grafts used. The main concern seems to be the adequacy of the LIMA flow for all target vessels with increased demand and the risk of insufficient perfusion.
There is a concern that the flow reserve of the LIMA, in the case of composite graft use, may not be enough for all vessels that have been anastomosed to the composite graft. Wendler et al8 have measured the proximal LIMA flow 1 week and 6 months after the operation using a Doppler guidewire in patients who received a t-graft with RA. Basal flows and maximum flow measurements after a 30 mg adenosine infusion were performed. Measurements at the first week revealed a basal flow of 72.65 ± 34.78 ml·min–1 and a maximum flow of 130.83 ± 58.80 ml·min–1. Measurements at 6 weeks showed a mild decrease in the basal flow and a mild increase in the maximal flow and they concluded that t-graft configuration provided a sufficient flow to the myocardium with a near normal coronary flow reserve.
In the t-graft technique, total coronary bypass flow is dependent on the LIMA flow. According to Barner,13 t-graft configuration is not associated with hypoperfusion, which is a sign of surgical technical failure. Hypoperfusion associated with a t-graft should initially be thought of as an insufficient flow in proximal LIMA. Proximal flow is dependent directly on the significant difference of the proximal and distal end diameters (1 mm or more) of the LIMA. A 2 mm conduit diameter gives a 3.14 mm2 luminal cross-sectional area, a 2.5 mm conduit diameter gives a 4.90 mm2 luminal cross-sectional area, and a 3 mm conduit diameter gives a 7.06 mm2 area. As is clearly seen, a 3 mm diameter reveals more than two times the cross-sectional area of a 2 mm conduit. Barner13 reports hypoperfusion in 3 out of 550 patients who had a t-graft. Hypoperfusion is mostly due to graft injury during harvesting, stretching of the graft with a short length, technical failure, kinking of the graft or over-linear tension. Markwirth et al14 showed that after complete arterial revascularization with a t-graft, LIMA flow was affected by the native artery flow quantitatively and, as a result of the competitive flow phenomenon, flow in the bypass grafts on the stenotic coronary artery were significantly lower than that of the bypass grafts anastomosed to the occluded vessels.
Radial artery t-graft is a preferred option in all patients under 70 years old and with an ejection fraction of more than 35%. Under the age of 60 years, it may also be used in patients with left ventricular dysfunction (LVD). In patients with peripheral artery disease, diabetes, old age and chronic renal failure requiring dialysis, radial t-graft can still be used despite a higher risk for medial calcification. Composite grafts are not preferred in cases in which a concomitant procedure is performed, but if the life expectancy permits and no other conduits are available, they can also be used.15
Generally, an arterial graft which is proximally anastomosed to the aorta behaves in the same manner as a venous graft in the first year after the operation. After this period, they share a common fate with other pediculated arterial grafts. Loop et al16 reported the patency rate of a free internal mammary artery at 18 months as 77%, Suma et al17 reported that after a 2–5-year period, the patency rate of an in situ right gastroepiploic artery was 96% and a free right gastroepiploic artery was 75%. Calafiore et al4 gave two possible explanations for this. The first is the discordant wall thickness and the second one is the mismatch of the diameters of the aorta and the graft. These conduits, when anastomosed to the aorta, with the sudden rise of pressure wave causing intimal tear and stretching, may cause intimal hyperplasia to develop prematurely. In contrast to the early results, mid-term results of the control angiographies in the t-graft group were inferior to the expected results (45%). For the composite grafts of LIMA and RA, Wendler et al8 reported patency rates of 98.2% at 1 week and Calafiore et al4 reported 93.1% at 18.5 ± 10.4 months.
Patency rates in the group anastomosed to the ascending aorta were found to be 96.8%. This outcome led us to consider the appropriateness of the technique used for the preparation of the composite grafts. In another study from our clinic, the patency rate of RA grafts anastomosed proximally to the ascending aorta and distally to a single coronary artery was 73.3% at 15 ± 0.9 months.18 The 23.3% prevalence of RA spasms was also stressed in this study. This outcome indicates that along with the composite graft preparation technique, RA harvesting also needs to be revised.
In spite of the inferior patency in the t-graft group, the good postoperative hemodynamic and clinical results for early follow-up point to the event causing the graft failure as an intimal injury rather than an anastomotic technical failure. In the individual RA use, 16.6% occlusion rates and 23.3% spasm rates seem to support this finding.
LIMA-RA anastomosis is performed prior to the onset of cardiopulmonary bypass in some clinics while others prefer to do it after distal anastomoses. We performed it after the completion of the distal anastomoses.
Tector et al9 recommend that the LIMA-RA anastomosis be done before the start of cardiopulmonary bypass which would allow not only a lesser perfusion time but also provides the possibility for controlling the flow of both ends of the graft, and if insufficient, allows the surgeon to revise the graft. In the case of an extra length of RA, excision can be performed from the smaller and less favorable distal end. For the RA anastomosis on the LIMA, surgeons have not reached a concensus for the length of the arteriotomy and limits are highly variable. For example, Barner15 used a 0.5 cm arteriotomy while Dietl and Benoit19 used a 2 cm arteriotomy on the lower face of the LIMA to avoid any kinking. We performed a 0.5 cm arteriotomy on the LIMA. With a small diameter, a long arteriotomy may affect patency but may also cause steal from the left anterior descending branch.
In conclusion, sequential distal anastomosis of the RA gives superior results to saphenous vein grafts and individual RA grafts only when the proximal anastomosis is performed on the ascending aorta, and not on the LIMA. A higher number of controls are required for more accurate results, but the sequential use of an RA graft seems to be effective and safe if the proximal anastomosis is performed on the ascending aorta.
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REFERENCES
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- Acar C, Jebara VA, Portoghese M, Fontaliran F, Dervanian P, Chachques JC, et al. Comparative anatomy and histology of the radial artery and the internal thoracic artery. Implication for coronary artery bypass. Surg Radiol Anat 1991;13:283–8.[Medline]
- Acar C, Jebara VA, Portoghese M, Beyssen B, Pagny JY, Grare P, et al. Revival of the radial artery for coronary artery bypass grafting. Ann Thorac Surg 1992;54:652–60.[Abstract]
- Calafiore AM, Di Giammarco G, Luciani N, Maddestra N, Di Nardo E, Angelini R. Composite arterial conduits for wider arterial myocardial revascularization. Ann Thorac Surg 1994;58:185–90.[Abstract]
- Yilmaz AT, Özal E, Barindik N, Gunay C, Tatar H. The results of radial artery Y-graft for complete arterial revascularization. Eur J Cardiothorac Surg 2002;21:794–9.[Abstract/Free Full Text]
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ABSTRACT
INTRODUCTION
