Pedicled or skeletonized? A review of the internal thoracic artery graft

The internal thoracic artery is the gold-standard conduit for coronary artery bypass surgery. Until recently, it was used almost exclusively as a pedicle, with construction of 1 distal anastomosis. Skeletonization of the internal thoracic artery has recently been advocated in order to increase the number of arterial anastomoses and decrease the occurrence of sternal wound infections. When skeletonized, the vessel loses its "milieu" which raises the question of whether this technique sacrifices the superior longevity of the conduit. The current status of research on the effects of skeletonization (depriving the internal thoracic artery of vasa vasorum, innervation, and lymphatic and venous drainage, together with creating an imbalance between vasoconstricting and vasodilating substances) appears to support the superiority of the pedicled graft. Long-term patency studies of the skeletonized ITA, with meticulous follow-up and confirmation by angiography, are not currently available. Theoretically, skeletonization of the ITA might adversely affect its long-term resistance to atherosclerosis. More data are needed before this technique can be universally recommended. If the skeletonized ITA has decreased long-term patency, bypass surgery may be at a disadvantage when compared with the new generation of drug-eluting stents.

Myocardial revascularization using the arterial T graft: which conduit should be chosen for the free graft?

BACKGROUND

The T graft is achieved by the end-to-side implantation of a free arterial graft into the left internal thoracic artery, which remains in situ. Which conduit is best suited as the free graft is still being discussed.

METHODS

Two groups of patients are compared. The right internal thoracic artery (RITA) was used as a free graft in group I (n = 129), and the radial artery was used in group II (n = 84).

RESULTS

The RITA was used more often with male patients (P < .02) and with patients presenting a reduced left ventricular ejection fraction (P < .03). The average number of coronary anastomoses per patient was higher in group II than in group I (P < .002). There were no significant differences between the groups in early mortality (0.8% in group I and 1.2% in group II) and morbidity. Postoperative chest tube output was significantly higher in group I than in group II (P < .05). The mean follow-up time was 35.2 +/-28.3 months. There were no significant differences regarding late mortality (6.9% in group I and 5.3% in group II) and the recurrence of angina (group I, 6 cases or 5.5%; group II, 3 cases or 4.2%). Because of the recurrence of angina or questionable chest pain in 22 patients, angiography was performed, and results showed a patency rate of 90.9% in group I and 93.1% in group II.

CONCLUSIONS

Based on our experience, we advise using the RITA as a free graft with tall men and also in patients with a reduced left ventricular ejection fraction, diabetes, and obesity. The radial artery should be used with small women if there is a high risk of bleeding and if several coronary anastomoses are necessary.

An automatic sutureless coronary anastomotic device: initial results of an animal study

BACKGROUND

The efficacy and long-term patency of a new distal anastomotic device (DAD) for the creation of rapid, sutureless end-to-side venous or arterial coronary artery bypass graft anastomoses were tested in a sheep model.

METHODS

The DAD was used on the beating hearts of 34 sheep to create 20 anastomoses between saphenous veins (n = 9) or internal mammary arteries (n = 11) and various coronary arteries. Fourteen conventional hand-sutured anastomoses (7 veins; 7 internal mammary arteries) served as controls. The sheep were sacrificed 1 day, 1 week, and 1, 3, and 6 months after surgery.

RESULTS

The immediate patencies of all anastomoses were proven by the rates and pattern of flow. There were no significant differences between the DAD and suture anastomosis groups in presacrifice pulsatility index and occlusion rate. The histomorphometric studies showed complete intimal bridging over the DAD with no significant differences between DAD and suture anastomoses with respect to tissue response, mural injury, inflammation, and adventitial fibrosis.

CONCLUSIONS

The DAD enables the creation of rapid, efficient, and sutureless venous or arterial coronary anastomoses. The long-term results of histomorphometric studies show that the results with the DAD are comparable with those of conventional hand-sutured anastomoses.

Beating heart revascularization using only bilateral internal thoracic arteries for triple-vessel disease: early angiographic findings

BACKGROUND

Early postoperative coronary angiography was performed to establish the feasibility of treating patients with triple-vessel disease by performing completely arterial revascularization on the beating heart using only bilateral internal thoracic arteries (ITAs).

METHODS

Between March 2001 and February 2003, 113 patients with triple-vessel disease (age, 62.0 +/- 8.6 years) underwent beating heart revascularization using only the bilateral ITAs. Left ventricular ejection fractions ranged from 23% to 78% (mean, 51.3% +/- 15.1%). The incidence of diabetes mellitus was 46%. Early postoperative coronary artery angiographic follow-up was performed since May 2002 in the last 59 sequential patients.

RESULTS

There were no operative deaths. Perioperative myocardial infarction and postoperative low cardiac output occurred in only 1 patient each. The mean number of distal anastomoses was 3.9 +/- 0.7 per patient. The patency rates were 100% for the left ITA and 98.1% for the right. Competitive flow patterns were present in 25 distal anastomosis sites (10.5%). A multivariate analysis showed that the degree of stenosis (<75%), the extent of focal stenosis of the native coronary artery, and the intraoperative transit-time flow rate (<10 mL/min) were the statistically significant risk factors for competitive flow.

CONCLUSION

This surgical strategy is feasible, is safe, and yields good early angiographic outcomes, even following beating heart revascularization. However, in less significant lesions competitive flow patterns were relatively prevalent, so this technique might be reserved until it is proven to provide good long-term patency and function.

Treatment of refractory coronary vasospasm during cardiopulmonary bypass with compulsory coronary perfusion

Coronary vasospasm is still a devastating complication during cardiac surgery. We report on a case of intractable coronary vasospasm in a 45-year-old male during coronary bypass surgery refractory to drugs and intra-aortic balloon pumping (IABP). Under cardiopulmonary bypass (CPB) support, the aorta was again cross-clamped and the aortic root was compulsorily perfused with pump blood using a small pump for infusion of cardioplegia. Vasodilators were administered through the perfusion line. Coronary vasospasm was dramatically resolved. He was then successfully weaned from CPB and recovered without further incidents.

Pharmacological studies on internal mammary artery bypass grafts. Action of endogenous and exogenous vasodilators and vasoconstrictors

BACKGROUND

The purpose of this experiment was four-fold: 1) to determine the effect of currently used cardiovascular drugs on internal mammary artery (IMA) vascular tone, 2) to examine IMA reactivity to autacoids and products released from aggregating platelets, 3) to compare the vascular reactivity of the right versus left IMA, and 4) to determine whether the canine IMA was an acceptable physiological model as regards its similarity to the human IMA, which is used routinely for coronary artery bypass grafting.

METHODS

To study factors that modulate the tone of IMA, bypass grafts, right and left canine IMAs were studied in vitro in organ chambers (95% O(2)/5% CO(2), pH=7.4).

RESULTS

Increasing concentrations (10(-9) to 10(-4M)) of the neurotransmitter acetylcholine (ACH) and the platelet-derived products adenosine diphosphate (ADP) or serotonin (5-HT) induced vasodilatation of contracted right and left IMAs. The vasodilation caused by ACH and ADP was endothelium-dependent while serotonin acted directly on the vascular smooth muscle. Histamine and bradykinin also induced IMA vasodilation, histamine via a direct action on the smooth muscle, and bradykinin through the release of nitric oxide (NO). In canine IMAs, the calcium ionophore A23187 produced endothelium-dependent vasodilation of contracted blood vessels; this vasodilation was blocked by N(G)-nitro-L-arginine (10(-4)M), a competitive inhibitor of nitric oxide synthesis from L-arginine, and by hemoglobin (10(-5)M). Dopamine, dobutamine, and papaverine induced vasodilation of the IMA regardless of the presence or absence of an intact intima, while norepinephrine induced profound IMA vasoconstriction, which was comparable to contraction to potassium ions or the constrictor peptide endothelin.

CONCLUSIONS

These experiments establish a pharmacological profile of IMA and demonstrate that endogenous and exogenous compounds can significantly alter its vascular tone.

Coronary revascularization in the 21st century. Emphasis on contributions by Japanese surgeons

The first three decades of coronary artery surgery have provided the foundation for the next century of this evolution. It is apparent that a multitude of events including the development of cardioplegia, improving surgical instrumentation, technological advances including endoscopic approaches and computer assisted robotics and biologic discoveries such as the role of the endothelium have provided the underpinnings for improved surgical outcomes. However, the single most important determinant of late results is the type of bypass conduit used for grafting. Thus, use of the left internal thoracic artery (ITA) grafted to the left anterior descending coronary is a more important determinant of survival than is any other factor (progression of coronary artery disease, increased age, poor left ventricular function, diabetes, female gender and off-pump operations). Use of two ITAs provides further benefit and it is likely that three or more arterial conduits will be shown to be advantageous in this regard in due time. Japanese cardiothoracic surgeons have made significant contributions to the continuing evolution of coronary bypass surgery and particularly to the advance of arterial conduits. This report will address those contributions to this evolution.

Totally endoscopic bilateral internal thoracic artery bypass grafting in a young diabetic patient

BACKGROUND

The introduction of robotics into cardiosurgical practice in 1998 has enabled totally endoscopic closed chest procedures. Totally endoscopic grafting of the LAD (TECAB) is no longer an experimental procedure.

CASE REPORT

We report on a case with totally endoscopic bilateral internal thoracic artery bypass grafting to the left anterior descending and right coronary artery in a 36-year-old obese female diabetic patient using the daVinci surgical system. The patient, suffering from juvenile diabetes for 26 years, presented with stable angina (CCS class II). A coronary angiogram revealed 2-vessel disease with a long complex proximal lesion of the left anterior descending artery (LAD) (90%) and 80% stenosis of the proximal right coronary artery (RCA). Due to the condition of the proximal LAD (high risk PTCA with rather poor prognosis), the patient was referred for minimally invasive operative revascularisation of the LAD and the RCA. After informed consent was obtained the patient underwent totally endoscopic double internal thoracic artery bypass revascularisation on the arrested heart using computer-enhanced telemanipulation technology.

RESULTS

The feasibility and safety of successful closed chest, totally endoscopic double coronary bypass grafting with two internal thoracic arteries is demonstrated in this case. Preservation of a stable chest cavity and reduced risk for wound healing complications in diabetics with an excellent cosmetic result are the obvious advantages of the techniques described.

Free right internal thoracic artery composite graft: an option in left anterior descending artery grafting?

Myocardial revascularization using bilateral internal thoracic arteries (ITA) decreases the risk of reinterventions and provides potential survival benefit. From May 1996 to April 2000, 1,057 patients underwent myocardial revascularization using skeletonized bilateral ITAs. A free right ITA as a composite graft was used for the left anterior descending artery grafting in 38 (3.6%) cases when the left ITA was not long enough to reach the left anterior descending artery. Operative mortality was 2.6% (1 patient). There was no observable reversible myocardial ischemia on the postoperative thallium single-photon emission computed tomography study. Myocardial revascularization with the use of a skeletonized free right ITA as a composite graft to the left anterior descending artery is an alternative option in cases when an in situ ITA cannot be used.

[Reoperative off-pump coronary artery bypass surgery for restenosis after percutaneous coronary intervention as a part of hybrid revascularization chronic renal failure on hemodialysis; report of a case]

60-year-old man on chronic hemodialysis had hybrid revascularization. Percutaneous coronary intervention (PCI) for right coronary artery (RCA) combined with left internal mammary artery-left anterior descending artery anastomosis through left anterior small thoracotomy were performed. But, frequent re-stenosis after PCI necessitated 4 repeated PCI. Finally, the patient agreed to re-do, and underwent reoperative off-pump coronary artery bypass through midsternotomy. Right internal mammary artery-saphenous vein lengthened composite graft was successfully anastomosed to heavily calcified RCA without heart-lung machine. Strategy of revascularization for hemodialysis patient was discussed.

Coronary bypass graft patency in patients with diabetes in the Bypass Angioplasty Revascularization Investigation (BARI)

BACKGROUND

Few studies have compared long-term status of bypass grafts between patients with and without diabetes, and uncertainty exists as to whether diabetes independently predicts poor clinical outcome after CABG.

METHODS AND RESULTS

Among 1526 patients in BARI who underwent CABG as initial revascularization, 99 of 292 (34%) with treated diabetes mellitus (TDM) (those on insulin or oral hypoglycemic agents) and 469 of 1234 (38%) without TDM had follow-up angiography. Angiograms with the longest interval from initial surgery and before any percutaneous graft intervention (mean 3.9 years) were reviewed. An average of 3.0 grafts were placed at initial CABG for patients with TDM (n=297; internal mammary artery [IMA], 33%) and 2.9 grafts for patients without TDM (n=1347; IMA, 34%). Patients with TDM were more likely than those without to have small (<1.5 mm) grafted distal vessels (29% versus 22%) and vessels of poor quality (9% versus 6%). On follow-up angiography, 89% of IMA grafts were free of stenoses > or =50% among patients with TDM versus 85% among patients without TDM (P=0.23). For vein grafts, the corresponding percentages were 71% versus 75% (P=0.40). After statistical adjustment, TDM was unrelated to having a graft stenosis > or =50% (adjusted odds ratio, 0.87; 95% CI, 0.58 to 1.32).

CONCLUSIONS

Despite diabetic patients' having smaller distal vessels and vessels judged to be of poorer quality, diabetes does not appear to adversely affect patency of IMA or vein grafts over an average of 4-year follow-up. Previously observed differences in survival between CABG-treated patients with and without diabetes may be largely a result of differential risk of mortality from noncardiac causes.

Outcomes in single versus bilateral internal thoracic artery grafting in coronary artery bypass surgery

The authors analyzed the early outcomes in two groups of patients undergoing coronary artery bypass grafting (CABG) with single versus bilateral internal thoracic arteries (ITA) in their institution. One thousand sixty-nine patients underwent CABG with single or bilateral ITAs from 1990 to 2000. Of these patients, 911 (85.2%) had single ITA and 158 had bilateral ITA (14.8%). The incidence of tobacco abuse was 40.3% in the single ITA group and 56.7% in the double ITA group (P = 0.0001). The incidence of perioperative myocardial infarction, renal failure, reoperation for bleeding, stroke, or operative mortality did not differ in the two groups. There was a 4.4% incidence of mediastinitis in the bilateral ITA group versus 2.2% in the single ITA group (P = 0.0602). Early outcomes after bilateral ITA grafting for CABG are similar to single ITA grafting. Careful judgment should be exercised in selecting patients for bilateral ITA grafting, particularly if the patient smokes.

Malignant internal mammary lymph nodes during mobilization of the internal mammary artery

Malignant internal mammary node involvement may occur with a primary neoplasm or with metastasis. The incidental discovery of malignant internal mammary nodes from an unknown primary origin has not been previously described. Cardiac surgeons should be aware of pathologic internal mammary artery (IMA) nodes and any abnormally enlarged nodes encountered in the course of IMA mobilization should be sent for histological examination. The incidental discovery of malignancy does not preclude the use of the IMA as a bypass conduit. Once a diagnosis of malignancy is established, meticulous exhaustive investigation may be indicated to identify the primary lesion and definitive treatment instituted if appropriate.

[Early and mid-term results of all arterial graft coronary artery bypass grafting using bilateral internal thoracic and radial arterial conduits]

From March 1996 to May 2000, 41 patients [age 39-78 (mean 63.5 +/- 8.8) years, 90.2% male] underwent all arterial multiple coronary artery bypass grafting (CABG) using bilateral internal thoracic (BiITA) and radial (RA) arterial conduits. The reason for using RA was that the right gastroepiploic artery (RGEA) was small or occluded on preoperative angiography, a history of upper abdominal surgery or disease, or the right coronary arterial lesion was proximal and mild. The BiITA were used as in situ grafts and the proximal anastomosis of RA was to the ascending aorta in all cases. All patients underwent conventional elective CABG with median sternotomy using cardiopulmonary bypass. The mean number of anastomoses was 3.3 +/- 0.5 branches and complete revascularization rate was 80.5%. Postoperative follow-up averaged 20 months and the longest was 50 months. There was no early death, and overall graft patency 2-3 weeks after surgery was 96.2% (LITA 94.0%, RITA 97.6%, RA 97.6%). Four-year actuarial survival rate was 96.4 +/- 3.5% (1 patient: 9 months, no cardiac death), and cardiac event-free rate after surgery was 89.7 +/- 4.9% [4 patients: percutaneous transluminal coronary angioplasty (PTCA)]. However, once patients were discharged from hospital, cardiac event-free rate was 100%. These excellent results suggest that all arterial graft CABG was satisfactory, and RA can be used as a third suitable arterial bypass conduit, if RGEA cannot be used or is unsuitable for use.

Arterialization in coronary artery surgery in Japan and Hong Kong

In the 35 years of coronary artery bypass grafting, several kinds of conduits have been utilized and assessed. It is clear now that the saphenous vein graft deteriorated with time mainly due to atherosclerosis in the graft called "vein graft disease." The internal thoracic artery graft, on the contrary, stays patent very well in the long-term period and this evidence directly related to the superior later outcome in terms of longevity and postoperative cardiac events. To extend the use of arterial conduits for myocardial revascularization, several autologous arteries have been investigated and utilized clinically. With proper use of these new arterial conduits in addition to internal thoracic artery, coronary artery bypass grafting with multi-arterial grafts can be performed safely, and better long term result can be expected.

Sequential use of internal thoracic artery in myocardial revascularization: mid- and long-term results of 430 patients(1)

BACKGROUND

There is still controversy about early and late results of sequenital use of internal thoracic artery (ITA) in coronary artery bypass (CAB) operations.

METHODS

In this study, we report on a series of 430 consecutive patients who underwent CAB operations between 1986 and 1998, with the use of at least one sequential ITA graft. The patients, 379 men and 51 women had a mean age of 56.4 years (range 29-80 years). Both ITA grafts were used in 227 (52.8%) patients. A total of 1744 (mean 4.05 per patient) distal coronary anastomoses were performed: 1172 of which (mean 2.72) were arterial and 980 (mean 2.28) were sequential ITA anastomoses.

RESULTS

Thirty-day mortality was 1.8% (n=8 patients). Perioperative myocardial infarction occurred in 12 patients (2.8%) and five of them (1.2%) were confined to the sequential ITA grafted area. Follow-up ranged from 1 month to 13 years (mean 63+/-37.7 months) for 372 patients (86.5%). Nine patients died during follow-up period. According to Kaplan-Meier method, 5 and 10 year survival rates were 95.6 and 93.4%, respectively. Coronary angiography was performed in 64 patients (17.2%) after a mean of 33 months. In 31 of these patients angiography was performed due to return of symptoms. Overall patency rate of sequential ITA anastomoses was 91.7% (111/121). Two patients underwent repeat CAB operations.

CONCLUSION

Sequential use of ITA grafts was not associated with the increased perioperative mortality and morbidity and has the potential to improve the long-term results of CAB surgery because of excellent patency rates of sequential ITA anastomoses.

Subclavian coronary steal syndrome: an obligatory common fate between subclavian artery, internal mammary graft and coronary circulation

The long-term patency of the left internal mammary artery (IMA) has made it the preferred conduit for myocardial revascularization. The proximal segment of the subclavian artery becomes functionally connected to the coronary circulation as a result of IMA implantation during coronary artery bypass surgery. The subclavian coronary steal syndrome results from stenosis in the left subclavian artery proximal to the IMA, compromising blood flow to the myocardium. We describe 7 patients, aged 55-75 years, 1.7-10.5 years after coronary bypass who presented with recurrent angina due to subclavian artery stenosis. The IMA graft was found open in each patient. A true steal mechanism was not demonstrated, casting doubt on the syndrome's traditional name. Angioplasty and stenting of the subclavian artery resulted in the immediate disappearance of angina and continuous benefit at a follow-up of 3-32 months. The subclavian coronary steal syndrome, although rare, is a severe condition readily treated by angioplasty and stenting.

The impact of diabetic retinopathy on long-term outcome following coronary artery bypass graft surgery

OBJECTIVES

We sought to assess the impact of diabetic retinopathy on long-term outcome among patients with diabetes and multivessel coronary artery disease (MVD) following coronary artery bypass graft surgery (CABG).

BACKGROUND

For diabetics, CABG is the preferred revascularization strategy. Diabetic retinopathy is a major microvascular complication of diabetes, and its severity is directly related to total glycemic exposure.

METHODS

We identified 223 consecutive diabetics with MVD whose retinae were evaluated within one year prior to CABG. The most recent ophthalmologic records up until the time of CABG were used to evaluate the severity of retinopathy. The median follow-up after CABG was 11.6 years.

RESULTS

Diabetic retinopathy was a strong independent predictor of overall mortality (relative risk [RR], 4.0), and repeat revascularization (RR, 3.0). In separate analyses of diabetics with retinopathy and without retinopathy, predictors of mortality differed significantly between the two groups. Among diabetics with retinopathy, the presence of either preoperative renal (RR, 2.5) or ventricular (RR, 2.0) dysfunction had unfavorable effects on mortality, but the survival curves did not differ significantly according to the presence or absence of internal thoracic artery (ITA) grafting. In comparison, among diabetics without retinopathy, ITA grafting (RR, 0.34) had a beneficial effect on mortality, and the survival curves varied somewhat according to the presence or absence of renal or ventricular dysfunction.

CONCLUSIONS

Diabetics with retinopathy had a distinct post-CABG course with a worse long-term prognosis, as compared with diabetics without retinopathy. Retina evaluation is useful for prediction of long-term prognosis and management of diabetics who need CABG.

Acute pleuropulmonary complications detected by computed tomography following myocardial revascularization

INTRODUCTION: Pleuropulmonary changes are common following coronary artery bypass grafting surgery performed with a saphenous vein graft, with or without an internal mammary artery. The presence of atelectasis or pleural effusions reflects the thoracic trauma. PURPOSE: To define the postoperative incidence of changes in the lung and in the pleural space and to evaluate the influence of the trauma. METHODS: Thirty patients underwent elective coronary artery bypass grafting surgery (8 saphenous vein grafts and 22 saphenous vein grafts and internal mammary artery grafts with pleurotomy). Chest tubes in the left pleural space were used in all internal mammary artery patients. On the second (day 2) and seventh (day 7) postoperative day, patients underwent a computed tomography, and pleural effusions were rated as follows: grade 0 = no fluid to grade 4 = fluid in more than 75% of the hemithorax. Atelectasis was rated as follows: laminar = 1, segmental = 3, and lobar = 10 points. RESULTS: All patients had pleural effusion or atelectasis. Between day 2 and day 7, the number of patients with effusions or atelectasis on the right side decreased (P < 0.05). The incidence of effusions on day 2 in the saphenous vein graft group (87.5%) was higher (P < 0.05) than in the internal mammary artery group (52.3%). The incidence of atelectasis in the lower right lobe decreased (P < 0.05) from 86.7% (day 2) to 26.7% (day 7). The degree of atelectasis in both sides did not differ on day 2 (P = 0.42) but did on day 7 (P < 0.0001). There was a decrease in the atelectasis from day 2 to day 7 on the right side (P < 0.001), but not on the left (P = 0.21). On day 2 there was a relationship between atelectasis and effusion on the right (P = 0.04), but not on the left (P = 0.113). CONCLUSION: The present series demonstrates that there is a high incidence of both minimal pleural effusion and atelectasis after coronary artery bypass grafting surgery, which drops on the right side from day 2 to day 7 post surgery. Factors that contribute to the persistence of changes on the left side include the thoracic trauma and the presence of chest tubes and pericardial effusion.