Healing basis and surgical techniques for complete revascularization of the left ventricle using only the internal mammary arteries

Bilateral internal thoracic artery grafting: propensity analysis of the left internal thoracic artery versus the right internal thoracic artery as a bypass graft to the left anterior descending artery

OBJECTIVES

To compare different configurations of the bilateral internal thoracic arteries for the left coronary system and examine early and late outcomes, including mid-term graft patency.

METHODS

We reviewed 877 patients who underwent primary isolated coronary artery bypass grafting using in situ bilateral internal thoracic arteries [in situ right internal thoracic artery (RITA)-to-left anterior descending artery (LAD) grafting, n = 683; in situ left internal thoracic artery (LITA)-to-LAD grafting, n = 194]. We compared mid-term patency between the grafts. Propensity score matching was performed to investigate early and long-term outcomes.

RESULTS

The 2-year patency rate for RITA-to-LAD and LITA-to-LAD grafts were similar. Multivariate analysis revealed that RITA-to-non-LAD anastomosis (P = 0.029), postoperative length of stay (P = 0.003) and chronic obstructive pulmonary disease (P = 0.005) were associated with graft failure. After statistical adjustment, 176 propensity-matched pairs were available for comparison. RITA-to-LAD grafting enabled a more distal anastomosis. Kaplan-Meier analysis revealed that the incidences of death, repeat revascularization and myocardial infarction were significantly higher in the LITA-to-LAD group among both the unmatched and matched samples (P = 0.045 and 0.029, respectively).

CONCLUSIONS

The mid-term patency and outcomes of RITA-to-LAD grafting are good and reduces future cardiac event, in contrast to LITA-to-LAD grafting.

Routine use of bilateral internal thoracic artery grafting in women does not increase in-hospital mortality and could improve long-term survival

BACKGROUND

Bilateral internal thoracic artery (BITA) grafting is underused in women.

METHODS

Outcomes of 798 consecutive women with multivessel coronary disease who underwent isolated coronary surgery (1999-2016) using BITA (n=530, 66.4%) or single internal thoracic artery (SITA) grafting (n=268, 33.6%) were reviewed retrospectively. Differences between BITA and SITA cohort were adjusted by propensity score matching. For both series, late survival was estimated with the Kaplan-Meier method.

RESULTS

One-to-one propensity score matching resulted in 247 BITA/SITA pairs with similar baseline characteristics and risk profile. According to the propensity matching, BITA grafting was associated with a trend towards reduced in-hospital mortality (3.2% vs. 5.7%, p=0.19). However, BITA women had an increased chest tube output (p=0.0076) as well as higher rates of any (13% vs. 5.3%, p=0.003) and deep sternal wound infections (9.3% vs. 4.9%, p=0.054), this translating in a longer in-hospital stay (10 vs. 9days, p=0.029). Test for interaction showed that body mass index >30kg/m² and extracardiac arteriopathy were associated with a higher risk of deep sternal wound infection in BITA than in SITA women (23.4% vs. 13.7%, p<0.001 and 23.9% vs. 3.4%, p=0.001, respectively). Freedom from all-cause death and cardiac or cerebrovascular death were improved in BITA cohort, even though the differences were not quite significant (p=0.16 and 0.076, respectively).

CONCLUSIONS

When routinely performed, BITA grafting does not increase in-hospital mortality in women and could improve long-term survival. However, its use should be avoided in obese women with extracardiac arteriopathy because of increased risk of deep sternal wound infection.

Composite Y Grafts From the Left Internal Mammary Artery: Current Considerations

The use of composite coronary artery bypass grafts from the left internal mammary artery (LIMA) has increased over the last 20 years. Total arterial revascularisation can be achieved with two arterial conduits and is associated with a reduced risk of stroke. However, the traditional coronary bypass graft configurations of the in situ LIMA and aorto-coronary saphenous vein grafts remain as the mainstay of coronary bypass surgery in most centres. Concerns regarding composite Y grafts relate to (1) the adequacy of a single inflow for all coronary bypass grafts; (2) the risk of compromising the LIMA flow to the left anterior descending coronary artery; (3) the effects of competitive flow on graft patency; and (4) the use of sequential coronary anastomoses. The evidence upon which these concerns are based will be discussed along with the evidence relating to the use of the various second conduit options.

Management and Prevention of Saphenous Vein Graft Failure: A Review

Coronary artery bypass grafting (CABG) remains a vital treatment for patients with multivessel coronary artery disease (CAD), especially diabetics. The long-term benefit of the internal thoracic artery graft is well established and remains the gold standard for revascularization of severe CAD. It is not always possible to achieve complete revascularization through arterial grafts, necessitating the use of saphenous vein grafts (SVG). Unfortunately, SVGs do not have the same longevity, and their failure is associated with significant adverse cardiac outcomes and mortality. This paper reviews the pathogenesis of SVG failure, highlighting the difference between early, intermediate, and late failure. It also addresses the different surgical techniques that affect the incidence of SVG failure, as well as the medical and percutaneous prevention and treatment options in contemporary practice.

Predictors of immediate and long-term outcomes of coronary bypass surgery in patients with left ventricular dysfunction

Despite encouraging improvements, outcomes of coronary artery bypass grafting (CABG) in the presence of left ventricular (LV) dysfunction remain poor. In the present study, the authors' experience on this subject was reviewed to establish the predictors of immediate and long-term results of surgery. Out of 4383 consecutive patients with multivessel coronary artery disease who underwent primary isolated CABG at the authors' institution from January 1999 throughout September 2014, 300 patients (mean age 66.1 ± 9.6 years) suffered preoperatively from LV dysfunction (defined as LV ejection fraction ≤35 %). The mean expected operative risk (EuroSCORE II) was 10.3 ± 13 %. Hospital deaths and perioperative complications were analyzed retrospectively. Outcomes were evaluated during a mean follow-up of 6.2 ± 4 years. None, one or both internal thoracic arteries (ITAs) were used in 6.3, 29 and 64.7 % of cases, respectively. There were 16 (5.3 %) hospital deaths. Prolonged invasive ventilation (17.7 %), acute kidney injury (14.7 %) and multiple blood transfusion (21.3 %) were the most frequent major postoperative complications. The 10-year non-parametric estimates of freedom from all-cause death, cardiac death, and major adverse cardiac and cerebrovascular events (MACCEs) were 47.8 [95 % confidence interval (CI) 44.1-51.5], 65.3 (95 % CI 61.4-69.2), and 42.3 % (95 % CI 38.3-46.3), respectively. Shared predictors of decreased late survival and MACCEs were old age (P < 0.04), chronic lung disease (P < 0.01), chronic dialysis (P < 0.0001) and extracardiac arteriopathy (P < 0.045). After adjustment for corresponding risk factors, freedom from cardiac death was higher when both ITAs were used but only for patients with significant increase of LV ejection fraction early after surgery (P = 0.04). In patients with LV dysfunction, CABG may be performed with acceptable hospital mortality and long-term survival. Late outcomes depend mainly on preoperative characteristics of the patients. The use of both ITAs for myocardial revascularization may give long-term survival benefits but only for patients whose LV function improves significantly early after surgery.

The Impact of Diabetes on Early Outcomes after Routine Bilateral Internal Thoracic Artery Grafting

BACKGROUND

Increased risk of postoperative complications limits use of bilateral internal thoracic artery (BITA) grafting in diabetic patients. The authors' experience in routine BITA grafting was reviewed to investigate the impact of diabetes on early outcomes.

METHODS

Among the 4508 consecutive patients with multivessel coronary artery disease who underwent isolated coronary bypass surgery from January 1999 throughout August 2015, skeletonised BITA grafts were used in 3228 (71.6%) patients, 972 diabetic and 2256 non-diabetic. After one-to-one propensity score (PS)-matched analysis, 819 pairs of diabetic/non-diabetic patients were compared for postoperative outcomes. The operative risk was calculated for each patient according to the European System for Cardiac Operative Risk Evaluation II (EuroSCORE II).

RESULTS

Although diabetic had higher risk profiles than non-diabetic patients both in unmatched (EuroSCORE II: 5.3±7.3% vs. 3±4.2%, p<0.0001) and PS-matched series (EuroSCORE II: 5.1±7.1% vs. 3.6±4.3%, p<0.0001), there were no differences in hospital mortality (2.2% vs. 1.8%, p=0.52 and 2.1% vs. 2.3%, p=0.74, respectively). In PS-matched pairs, the use of adrenergic agonists (p=0.03), postoperative bleeding (p=0.0055) and deep incisional sternal wound infection (p=0.0018) were more frequent in diabetic patients who had a mean of longer hospital stays (p=0.023).

CONCLUSIONS

Bilateral internal thoracic artery grafting may be routinely performed even in diabetic patients despite higher risk profiles. Increased postoperative complications prolong hospital stay but do not impact on early mortality.

Pure Bilateral Internal Thoracic Artery Grafting in Diabetic Patients With Triple-Vessel Disease

BACKGROUND

Despite the documented superior long-term patency of bilateral internal thoracic artery (BITA) grafting, use of BITAs remains low, especially in diabetic patients. We analyzed the results of pure BITA grafting to determine whether the potential survival advantage outweighs the risk of wound infection in diabetic patients.

METHODS

We performed a retrospective analysis of 791 consecutive patients (389 diabetic, 402 nondiabetic) with triple-vessel disease who underwent off-pump coronary artery bypass using only skeletonized BITAs from 2001 to 2010. We used propensity score matching to match 315 nondiabetic patients with diabetic patients.

RESULTS

The groups did not differ significantly regarding 10-year survival (diabetic, 84.2% ± 4.5%; nondiabetic, 80.8% ± 4.7%; p = 0.828) or freedom from major adverse cardiovascular events (diabetic, 73.5% ± 5.2%; nondiabetic, 71.8% ± 5.3%; p = 0.431). Diabetes was not predictive of deep sternal infection (odds ratio, 1.11; 95% confidence interval, 0.23 to 5.31; p = 0.895). Results of stratified competing risks regression analysis showed that the risk of target vessel revascularization in diabetic patients was similar to that of nondiabetic patients (subdistribution hazard ratio, 0.67; 95% confidence interval, 0.16 to 2.80; p = 0.585).

CONCLUSIONS

Off-pump coronary artery bypass grafting using pure BITAs produced excellent clinical outcomes in both diabetic and nondiabetic patients. This strategy did not increase the incidence of deep sternal infection in diabetic patients. We recommend BITA grafting, which has proven long-term patency, as a strategy of choice in diabetic patients.

Bilateral internal mammary artery grafting: rationale and evidence

Coronary artery bypass graft (CABG) surgery remains the preferred mode of revascularization in patients with complex multi-vessel coronary artery disease. The left internal mammary artery (IMA) and saphenous vein are the most commonly utilized conduits in CABG surgery and are still considered to be the gold standard by most surgeons. However, there is emerging evidence that use of bilateral IMAs is associated with significantly better long-term outcomes and the benefit increases with time from surgery. In spite of this incremental beneficiary effect, most surgeons are reluctant to use both IMAs, because it is technically more demanding, time-consuming and is associated with marginally higher sternal wound infection rates. This review highlights the histological features, physiological characteristics and genomics of IMAs that provide the basis for the use of these vessels during CABG surgery. Additionally, the superiority of the bilateral IMAs with regard to patency and long-term outcomes is also discussed in detail. Furthermore, the safety of using bilateral IMAs with regard to early postoperative outcomes with special reference to deep sternal wound infections has been addressed. The present review provides enough evidence to convince more surgeons about the advantages of bilateral IMA grafting.

Composite arterial grafting

The success of coronary artery bypass grafting, the gold standard for the treatment of multivessel coronary artery disease, is limited by poor long-term vein-graft patency. By contrast, the left internal mammary artery has been demonstrated to have a superior graft patency rate and has provided excellent clinical results. This suggests that the use of arterial conduits for coronary artery bypass grafting may be beneficial for long-term results. Recently, there has been an upsurge in the use of arterial grafts for myocardial revascularization based on the clinical advantage of the use of the left internal mammary artery as a bypass conduit. Many retrospective studies have supported the safety and the effectiveness of arterial grafting, and it has become apparent that the free arterial graft can be used as a branched or a lengthened conduit to the in situ arterial graft by adopting one or more of the several composite grafting techniques. Arterial composite grafts with or without sequential grafting techniques appear an attractive strategy as increased number of distal coronary anastomoses can be performed, with a limited number of grafts, avoiding proximal aortic anastomoses. However, concerns regarding the total dependence of the coronary bypass flow on the flow of one in situ arterial graft and technical error, resulting in compromised flow in one or both limbs of the composite graft have prevented composite arterial grafting from being universally adopted. It is expected that in the near future a prospective, multi-institutional, randomized controlled trial, to compare the short- and long-term outcomes of exclusive arterial grafting using composite and conventional aortocoronary revascularization strategies, will be undertaken to validate the safety and efficacy of composite arterial grafting.

Routine Use of Bilateral Skeletonized Internal Thoracic Artery Grafting

Background— Skeletonized harvesting of the internal thoracic artery (ITA) decreases the severity of sternal devascularization, thus reducing the risk of postoperative sternal complications in patients undergoing bilateral ITA grafting.

Methods and Results— Between 1996 and 2001, 1515 consecutive patients underwent skeletonized bilateral ITA grafting. Of the 1179 male and 336 female patients, 641 (42.3%) were >70 years of age, and 519 (34.2%) had diabetes mellitus. Operative mortality was 2.8%. Early postoperative morbidity included sternal infection (1.6%), cerebrovascular accident (3%), and perioperative myocardial infarction (1%). Multiple regression analysis showed chronic obstructive pulmonary disease (odds ratio, 11.3; 95% confidence interval [CI], 4.45 to 28.55), repeat operation (odds ratio, 12.7; 95% CI, 3.25 to 49.56), and diabetes mellitus (non–insulin dependent: odds ratio, 4.64; 95% CI, 1.85 to 11.59; insulin dependent: odds ratio, 6.9; 95% CI, 1.35 to 35.27) to be associated with increased risk of sternal infection. Follow-up (between 5 and 12 years) revealed 305 late deaths. Kaplan-Meier 10-year survival rates for patients <65, 65 to 74, and >75 years of age were 87%, 75%, and 52%, respectively. Cox regression analysis revealed increased overall mortality (early and late) in patients with peripheral vascular disease (hazard ratio [HR], 1.8; 95% CI, 1.39 to 2.33), patients >75 years of age (HR, 7.23; 95% CI, 4.16 to 12.55), those undergoing repeat operations (HR, 2.22; 95% CI, 1.27 to 3.89), patients with preoperative congestive heart failure (HR, 1.64; 95% CI, 1.29 to 3.75), and those with chronic renal failure (HR, 1.52; 95% CI, 1.11 to 2.01). Operations performed without cardiopulmonary bypass were associated with better postoperative survival (HR, 0.66; 95% CI, 0.49 to 0.87).

Conclusions— Bilateral ITA grafting is associated with low morbidity and good long-term results. Use of skeletonized bilateral ITA is appropriate for the elderly and most patients with diabetes; however, it is not recommended for repeat operations or for patients with chronic obstructive pulmonary disease.

Configurations and classifications of composite arterial grafts in coronary bypass surgery

The aim of this review is to present the configurations and classifications of composite arterial grafts in coronary bypass surgery. Articles were collected by tracking references cited in the literature with regard to the configurations of composite arterial grafts in coronary bypass surgery. Figures of the configurations were drawn in accordance to the schematic drawings, angiograms, photographs, table contents or written captions of the literature. According to their structural nature, composite arterial grafts can be classified as: (i) alphabetical (Y, T, I, U, K, X and H) and (ii) complex grafts (TY, loop, pi and sling grafts). According to the conduits that form the composite graft, they can be classified as: (i) definite (all standard alphabetical grafts, classic pi and sling grafts); (ii) varying [internal mammary artery (IMA) loop, modified pi graft]; and (iii) indefinite conduit graft (TY graft). According to their application in coronary artery bypass grafting (CABG), they can be divided into complete arterial revascularization for: (i) triple vessel disease (T, Y, K, X, TY, pi and sling grafts); (ii) two vessel disease (U, right Y, and two-thirds right IMA T grafts); and (iii) single vessel disease, mainly the left anterior descending artery with or without the diagonal branch (H, I, IMA loop and left IMA T grafts). According to the CABG method, they can be classified as: (i) for conventional CABG (sling graft); (ii) for minimally invasive direct coronary artery bypass (H graft); and (iii) for both conventional CABG and off-pump coronary artery bypass (T, Y, U, K, I, TY, IMA loop, and pi grafts). Standard Y and T grafts have been accepted as the common figurations of composite arterial grafts to maximum graft length for the bypass of triple vessel disease. Composite arterial grafts overcome the limited availability of arterial conduits for performing total arterial myocardial revascularization, allow a gain in conduit length, and minimize the ascending aorta manipulation.

Perioperative and clinical-angiographic late outcome of total arterial myocardial revascularization according to different composite original graft techniques

Total arterial myocardial revascularization (TAMR) is advisable because of the excellent long-term patency of arterial conduits. We present early and midterm outcomes of five different surgical configurations for TAMR. Between January 1998 and May 2004, 112 patients (aged 56.5 +/- 4.5 years, 20% female) with three-vessel disease underwent TAMR. The internal mammary arteries (IMAs) were harvested in a sketelonized fashion. The surgical techniques for TAMR consisted in Y or T composite grafts (n = 88, 78%) constructed between the in situ right IMA (RIMA) and the free left IMA (LIMA) graft (n = 58) or the radial artery (n = 30) (RA) in three different configurations. The other techniques consisted in T- and inverted T-graft (n = 24, 22%) constructed between the RA conduit and the free LIMA graft in two different configurations. The mean follow-up time was 40 +/- 23 months. Postoperative angiographic control was performed in 76/111 (70%) patients. Overall, 472 arterial anastomoses (average 4.2 per patient) were performed. One (0.9%) patient, undergoing the inverted T-graft technique, died on postoperative day 2. Another patient (0.9%), undergoing the lambda-graft technique using both IMAs and RA, suffered a new myocardial infarction probably due to RA conduit vasospasm. One week after surgery, after the transthoracic echocardiographic Doppler with adenosine provocative test, the coronary flow reserve (CFR) at the LIMA and RIMA main stems were 2 +/- 0.4 and 2.4 +/- 0.3, respectively. At 12-month follow-up, after adenosine provocative test, the CFRs at the LIMA and RIMA stems were significantly higher than the values at 1 week after surgery within the same group; (LIMA)CFR (1 week) 2.4 +/- 0.3 (12 months) vs 2 +/- 04 (1 week), P = 0.002; (RIMA)CFR 2.58 +/- 0.4 vs 2.4 +/- 0.3, P = 0.001. The CFR at the RIMA main stem was higher in all measurements within the same group than in the LIMA main stem, but not significantly. In one patient undergoing the lambda-graft technique using both IMAs, the RIMA was found to have a string sign. Postoperative angiography in 50 patients showed that the patency rate for the LIMA was 100%, for the RIMA 97.3%, and for the RA 96.7%. Angiography at 3-year follow-up in 76 patients documented excellent patency rates of the LIMA (97.4%), RIMA (95%), and RA (87%). Survival at 7 years was 92.5%, event-free survival 89.3%, and freedom from angina 94%. Total arterial myocardial revascularization using different surgical configurations is safe and effective. The use of composite arterial grafts provides excellent clinical and angiographic results, with a low rate of angina recurrence and late cardiac events. These configurations allow for complete arterial revascularization.

All internal thoracic artery composite graft revascularization

The aim of this study was to determine the most efficient design of composite grafts and clarify the technical feasibility rate of composite grafting using internal thoracic artery exclusively in patients undergoing triple-vessel revascularization. Retrospective analysis of 104 consecutive patients was carried out. An in situ left internal thoracic artery graft for the left anterior descending artery area, with attachment of the right internal thoracic artery to the side of the left internal thoracic artery to revascularize the circumflex and right coronary vessels, was the most efficient graft design. The technical feasibility rate was 80% (83/104 patients). The mean number of distal anastomoses for the entire group was 3.8+/-0.8 per patient. Intraoperative left internal thoracic artery flow rate was 91.6+/-37.8 mL.min-1. With more experience, it is thought that the technical feasibility rate could be increased.

Flow dynamics of the internal thoracic and radial artery T-graft

BACKGROUND

Complex use of arterial conduits has resurrected concerns about the adequacy of conduit flow. The T-graft is the extreme example of this trend. Our purpose was to identify the limitation of single source inflow and to compare flow capacity with completion coronary flow.

METHODS

Between February 1999 and November 2001, 372 patients underwent total arterial revascularization with the T-graft alone. Intraoperative flows were recorded for each limb of the T-graft before and after distal anastomoses in 204 patients. Independent predictors of T-graft flow were identified by multivariate analysis.

RESULTS

Free flow for the radial arterial (RA) limb was 161 +/- 81 mL/min, the internal thoracic artery (ITA) limb 137 +/- 57 mL/min (combined 298 +/- 101 mL/min) versus simultaneous limb flow of 226 +/- 84 mL/min giving a flow restriction of 24% +/- 14%. Completion coronary flow was 88 +/- 49 mL/min for the RA, 60 +/- 45 mL/min for the ITA, and 140 +/- 70 mL/min for both limbs simultaneously to give a flow reserve (vs simultaneous free flow) of 160% or 1.6. Independent predictors of completion RA limb flow are RA proximal diameter (p = 0.005), number of anastomoses (p = 0.018), and target stenosis (p = 0.005).

CONCLUSIONS

A flow reserve of 1.6 compares favorably with an ITA flow reserve of 1.8 at 1-month postoperatively and 1.8 for both the ITA T-graft and the ITA/RA T-graft at 1-week postoperatively as reported by others. Proximal RA diameter and competitive coronary flow influence completion T-graft flow. These data quantitate the limitation of single source inflow of the T-graft configuration and support its continued use.

Internal Thoracic Artery: To Skeletonize or Not to Skeletonize?

The internal thoracic artery has been the most reliable graft material used in coronary artery bypass grafting with an excellent long-term patency rate. Complete myocardial revascularization with internal thoracic arteries improves long-term survival and decreases the rate of repeat operations compared with vein grafts. Adequate length of the graft in coronary artery bypass graft surgery is essential for providing complete arterial revascularization. In the last decade or so, technique of skeletonization of internal thoracic artery has been proposed to achieve extra length. Skeletonization of the internal thoracic artery allows the preparation of longer conduits with a superior free flow and can reduce the incidence of postoperative pulmonary and sternal complications. However, concerns about vasoreactivity of skeletonized internal thoracic artery grafts, the functional consequences of surgical trauma, the possible loss of innervation, and vasa vasorum perfusion in the skeletonized conduits have prevented this technique from being universally accepted. Presently available evidence from retrospective studies (level 3 evidence) suggests that skeletonization is a safe and effective technique for myocardial revascularization. However, there is a need for conducting multicenter, randomized controlled trials comparing the skeletonized and pedicled internal thoracic arteries with special emphasis on long-term patency to conclusively validate the safety and efficacy of skeletonization technique.

Application of a chymase inhibitor, NK3201, for prevention of vascular proliferation

NK3201 is an orally active chymase inhibitor. Its inhibitory activity leads to formation of acyl-intermediate between active serine residue of the enzyme and di-ketone structure of NK3201. NK3201 inhibits human, dog and hamster chymases with IC(50) of 2.5, 1.2, and 28 nM, respectively. On the other hand, NK3201 does not inhibit other types of serine proteases, tryptase, thrombin, elastase, plasmin, and plasminogen activator. In dogs, at 8 h after oral administration of NK3201, 1 mg/kg, the drug levels in plasma, heart, and aorta reached 470, 195, and 78 nM, respectively. In a dog model NK3201, 5 mg/kg/day, increased chymase activity in grafted veins, and suppressed vascular proliferation. After balloon injury in dog vessels, chymase activity was increased locally, in the injured artery, and NK3201, 1 mg/kg/day was effective in preventing vascular proliferation. On the other hand, NK3201, unlike angiotensin converting enzyme inhibitors or angiotensin II receptor blockers, did not affect blood pressure. These findings indicate that local angiotensin II production by chymase is involved only in vascular proliferation, as seen in the injured vessels. Therefore, NK3201 may be useful for preventing vascular proliferation without affecting blood pressure.

A Single Treatment With a Specific Chymase Inhibitor, TY-51184, Prevents Vascular Proliferation in Canine Grafted Veins

In this study, we evaluated whether a specific chymase inhibitor, TY-51184 (2-[4-(5-fluoro-3-methylbenzo[b]thiophen-2-yl)sulfonamido-3-methanesulfonylphenyl]oxazole-4-carboxylicacid), prevents the vascular proliferation in canine grafted veins. In the placebo-and chymase inhibitor-treated groups, the external jugular vein was infiltrated with saline and 10 microM TY-51184, respectively, and then it was grafted to the ipsilateral carotid artery. The non-surgical dogs were used as the control group. By 28 days after grafting, the chymase and ACE activities were significantly increased in the injured arteries. TY-51184 significantly reduced the chymase activity in the grafted veins, while it did not affect the ACE activity. The intimal areas in the placebo- and TY-51184-treated groups were 3.32 +/- 0.16 and 1.96 +/- 0.52 mm(2), respectively, and this difference was significant. The ratios of intimal area to medial area in the placebo- and TY-51184-treated groups were 66.8 +/- 3.5% and 34.9 +/- 9.2%, respectively, and this difference was also significant. There was a significant relationship between vascular proliferation and chymase activity, but not ACE activity. In this study, we demonstrated that a single treatment with a specific chymase inhibitor, TY-51184, could prevent the vascular proliferation in canine grafted veins.

Technical aspects of composite arterial grafting with double skeletonized internal thoracic arteries

BACKGROUND

Complete myocardial revascularization with internal thoracic arteries (ITAs) improves long-term survival and decreases the rate of repeat operations, compared to vein grafts. Adequate length of the graft in coronary artery bypass graft (CABG) surgery is essential for providing complete arterial revascularization. Extra length can be obtained by skeletonization of both ITAs. In cases where the right ITA (RITA) is too short to bridge the distance to the target anastomotic site, it is used as a free graft in "composite" arterial grafting, a surgical technique in which free arterial conduits are proximally anastomosed end-to-side to an intact ITA.

OBJECTIVES

To describe alternative surgical procedures adapted to accommodate special anatomic requirements.

DESIGN

Retrospective study from April 1996 to April 1999.

PATIENTS

One thousand fifty patients underwent CABG surgery using bilateral skeletonized ITAs: 650 patients (482 men and 168 women; mean +/- SD age, 69 +/- 7 years) underwent composite arterial grafting. Two hundred sixteen patients (33.2%) were diabetics, 87 patients (13.4%) had severe left ventricular dysfunction (ejection fraction < 35%), and 27 patients (4.2%) underwent emergency operations.

INTERVENTIONS

The RITA was used as a free graft connected to the in situ left ITA (LITA) in 618 patients. A free LITA was attached to in situ RITA in 32 patients, and minicomposite grafts (free distal LITA on the LITA or free distal RITA on the RITA) were constructed in 38 patients. The average number of grafts was 3.2 per patient (range, 2 to 6 grafts per patient).

MEASUREMENTS AND RESULTS

Operative mortality was 2.9% (n = 19), and there were 11 sternal wound infections (1.7%). Early recatheterization was performed in 41 symptomatic patients. The patency rate was 95%. The mean follow-up was 25 months (range, 14 to 36 months), and the 3-year survival was 92.5%, with 97% of the surviving patients being angina free.

CONCLUSIONS

Planning CABG surgery using bilateral skeletonized ITAs as arterial conduits affords greater choice in grafting approaches, especially when a composite technique is feasible.

Internal thoracic artery grafts for the entire heart at a mean of 12 years

BACKGROUND

There is consensus today that the long-term results of bypassing the left anterior descending artery with an internal thoracic artery (ITA) graft are superior to those of a saphenous vein graft. Our hypothesis for this study was that three-vessel revascularization with only ITA grafts would also give excellent results.

METHODS

Using our previously described techniques to enhance the length of ITA grafts by skeletonization and high mediastinal mobilization, we were able to perform tension-free, three-vessel revascularization using only ITA grafts in 125 (83%) of a consecutive series of 150 patients with three-vessel occlusive coronary disease. We followed 100% of these 125 exclusive ITA graft patients (average of 3.9 anastomoses per patient) to their time of death (59; 47.2%) or current living status (66; 52.8%).

RESULTS

Combined intraoperative graft flows averaged 225 mL/min. Of the 125 patients in this study (average age, 63.5 years), 121 (96.8%) lived beyond 40 days. Of these 121 patients, 55 (45%) died at a mean of 7 years postoperatively and 66 (55%) are still living at a mean of 12.1 years. Of these 121 patients, 112 (93%) had angina at baseline. Of these 112, 92 (85%) were angina free at a mean of 9.1 years postoperatively. Freedom from infarction was 100% at 5 years and 97% at 10 years. Freedom from reintervention was 90% at a mean of 9.8 years.

CONCLUSIONS

Use of ITA grafts for three-vessel coronary revascularization provides excellent results and is both practical and appropriate for many patients.

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.

Significance of chymase-dependent angiotensin II-forming pathway in the development of vascular proliferation

BACKGROUND

Vascular tissues of humans and dogs contain chymase as an angiotensin II-forming enzyme. In this study, we investigated whether chymase-dependent angiotensin II formation plays a crucial role in the development of vascular proliferation in dog grafted veins.

METHODS AND RESULTS

The right external jugular vein of dogs was grafted to the ipsilateral carotid artery. As a control group, the right external jugular veins in dogs that had not received grafts were used. In the chymase inhibitor-treated group, the vein was infiltrated with 10 micromol/L Suc-Val-Pro-Phe(P)(OPh)(2) and was grafted to the carotid artery. In the placebo-treated group, ACE activity in the grafted veins was significantly lower than that in the control veins up to 7 days after the operation, whereas chymase activity was increased significantly. After 7 days, the mRNA levels of collagen I, collagen III, and fibronectin, all of which are induced by an increase of angiotensin II action, were significantly increased in the grafted veins, and the intima-media ratio of the grafted veins was also increased. In the chymase inhibitor-treated group, the chymase activity in the grafted veins 7 days after the operation was suppressed to 12.1%. The elevated mRNA levels of fibronectin, collagen I, and collagen III in the grafted veins were significantly suppressed by treatment with the chymase inhibitor, and the intima-media ratio was also decreased significantly.

CONCLUSIONS

We demonstrate for the first time that chymase-dependent angiotensin II formation plays an important role in the development of vascular proliferation in the grafted veins.

Arterial myocardial revascularization with in situ crossover right internal thoracic artery to left anterior descending artery

BACKGROUND

The extra length obtained by skeletonizing the internal thoracic arteries (ITAs) enables versatile use of in situ bilateral ITAs for coronary artery bypass grafting, as the longer skeletonized right ITA more easily reaches the anastomotic site on the left anterior descending coronary artery.

METHODS

Between April 1996 and November 1999, 365 consecutive patients underwent revascularization with bilateral in situ ITAs (29% of 1,250 grafting procedures performed with both ITAs in our department during this period). The right ITA was routed anterior to the aorta to graft the left anterior descending coronary artery, and the in situ left ITA was used to graft circumflex branches. Right coronary artery branches were grafted with right gastroepiploic artery or saphenous vein graft. The right ITA crossed the midline above the aorta at the most cranial point to avoid damage in case of a repeat sternotomy in the future.

RESULTS

The operative mortality rate was 2.2% (8 patients). Postoperative morbidity included seven strokes (1.9%), eight sternal wound infections (2.2%), and four perioperative myocardial infarctions (1.1%). Follow-up (6 to 49 months) of 97% of hospital survivors showed a return of angina in 3%. Postoperative coronary angiography (22 patients) revealed a 95% patency rate of both ITAs. One-year and 4-year survival rates (Kaplan-Meier) were 95% and 92.4%, respectively. Important predictors of an early unfavorable event were chronic obstructive pulmonary disease, old age (> or = 70 years), emergency operation, and diabetes. Chronic obstructive pulmonary disease was the only independent predictor of sternal wound infection (odds ratio, 15; 95% confidence interval, 2.8 to 80). It also predicted decreased late survival (hazard ratio, 8.3; 95% confidence interval, 3 to 21.5).

CONCLUSIONS

With skeletonized dissection of ITAs, the right ITA easily reaches the left anterior descending coronary artery for left-sided arterial revascularization with in situ bilateral ITAs. This procedure is safe, but we recommend avoiding its use in patients with chronic obstructive pulmonary disease.

Clinical and angiographic outcome of different surgical strategies of bilateral internal mammary artery grafting

Long-term survival, relief of angina, and prevention of myocardial infarction after coronary revascularization are related to the preoperative status of the patient, progression of coronary artery atherosclerosis, and the patency of the conduits used. The increased use of the internal mammary artery for coronary grafting depends upon the accumulation of data on superior late patency compared with venous conduits. These data have supported the simultaneous use of both left and right internal mammary arteries with reported improved late survival. However, controversy still surrounds the clinical and angiographic outcomes of some of the surgical strategies of bilateral internal mammary artery grafting. This review examines a range of surgical strategies of bilateral internal mammary artery grafting and their mid- and long-term clinical and angiographic outcomes. From the available data, careful preoperative selection of patients is paramount. Clinical and angiographic outcome of bilateral internal mammary grafting is superior to single internal mammary grafting with supplemental vein grafts when pedicled, sequential, or free aorto-coronary internal mammary artery is used. Further studies are needed to evaluate the midterm and long-term clinical and angiographic outcomes of complex strategies such as Y or T procedures.

Composite arterial grafting with double skeletonized internal thoracic arteries

OBJECTIVES

Composite arterial grafting is a surgical technique for arterial myocardial revascularization, in which free arterial conduits are proximally anastomosed end-to-side to an intact internal thoracic artery (ITA). This report describes technical aspects and results of composite grafting using bilateral skeletonized ITAs.

METHODS

From April 1996 to February 1999, 1057 patients underwent coronary artery bypass grafting (CABG) using bilateral skeletonized internal thoracic arteries. In 600 of them (57%), composite arterial grafting was performed. There were 452 men and 148 women. The mean age was 69 +/- 7 years. Two-hundred and six patients (34%) were diabetics, 84 (14%) had severe left ventricular dysfunction (ejection fraction of < 35%), and 26 (4.3%) underwent emergency operations. In 574 patients, the right ITA was used as a free graft connected to the in-situ left ITA. In 26, the free left ITA was attached to the in-situ right ITA, and in 38, mini-composite grafts (free distal left ITA on the left ITA, or free distal right ITA on the right ITA) were constructed. The average number of grafts was 3.0/patient (range, 2--6).

RESULTS

The operative mortality was 2.8% (n = 17), and there were ten (1.7%), deep sternal wound infections. The mean follow-up was 25 months (range, 14--36 months). The 3-year survival was 92.5%. Ninety-seven percent of the surviving patients were angina-free.

CONCLUSIONS

We currently perform this surgery routinely in most patients referred for CABG, and regard bilateral skeletonized internal thoracic arteries as the most appropriate arterial conduits for the composite technique.

Bilateral skeletonized internal thoracic artery grafts in patients with diabetes mellitus

OBJECTIVE

Increased risk of deep sternal infections has prohibited routine bilateral internal thoracic artery grafting in diabetic patients. The technique for harvesting the skeletonized internal thoracic artery provides the potential to minimize this risk. The purpose of this study was to compare the outcome of bypass grafting with bilateral skeletonized internal thoracic arteries in diabetic and nondiabetic patients.

METHODS

From May 1996 to April 1998, 231 consecutive diabetic and 534 nondiabetic patients underwent bilateral skeletonized internal thoracic artery grafting. Mean age was 66 years. Compared with the nondiabetic group, the diabetic group comprised more women (29% vs 18%, P =.001), had a greater prevalence of hypertension (53% vs 44%, P =.019) and congestive heart failure (20% vs 14%, P =.016), but a lower prevalence of preoperative acute myocardial infarction (26% vs 34%, P =.027).

RESULTS

Operative mortality of diabetic patients was comparable with that of nondiabetic patients (3% vs 2.6%). The two groups also had similar occurrences of deep sternal infection (2.6% vs 1.7%, respectively, P =.40). Deep sternal infection was significantly more prevalent in obese, diabetic women (3/20 = 15%) than in diabetic patients without this combination of risk factors (3/211 = 1.4%, P <.0001) (odds ratio 11.1, confidence interval 2.1-59.4). Diabetic patients also had a higher incidence of stroke (3.5% vs 0.9%, P =.014). Three-year actuarial survival of diabetic patients was lower (91.3% vs 94.7%, P =.083).

CONCLUSIONS

Bilateral skeletonized internal thoracic artery grafting is a good surgical revascularization option in diabetic patients. Operative mortality and prevalence of sternal infection are comparable with those of nondiabetic patients. However, the risk of sternal infection in obese diabetic women is high, and for them we advocate the use of a single artery instead of bilateral internal thoracic arteries.

Comparison of the flow capacity of free arterial grafts and saphenous vein grafts for coronary bypass surgery

There is controversy regarding the flow reserve and capacity of arterial conduits to meet the needs of the myocardium. This study compared flow in 22 free arterial bypasses to 15 saphenous vein grafts in procedures involving twenty patients. To assess the maximal flow possible, (flow capacity) graft flow was measured using a calibrated pump while perfusing blood cardioplegia through the conduit and distal anastomosis during cardiac arrest (no competitive flow). This assessment was subsequently confirmed with whole blood during myocardial contraction while on cardiopulmonary bypass. Twenty-two free arterial grafts were used; 15 right internal mammary artery grafts, 4 right gastroepiploic grafts, 3 inferior epigastric artery grafts, and 3 sequential bypasses. Free arterial conduit flow ranged from 50 to 180cc/ml, with an average flow of 102.5+/-28.5ml/min as compared to saphenous vein graft flow, 102+/-28 ml/min. No correlation of flow with the conduit size was found. Arterial graft flow demonstrated a mild correlation with the size of the native coronary artery bypassed (R=0.47, P</=0.02).

CONCLUSIONS

Basal flow through free arterial grafts is equivalent to saphenous vein grafts and is primarily determined by the native coronary vessels. The flow reserve for free arterial conduits is more than adequate for coronary bypass surgery.

All-artery multigraft coronary artery bypass grafting with only internal thoracic arteries possible and safe: a randomized trial

BACKGROUND

The internal thoracic artery (ITA) bypass to the left anterior descending coronary artery is of proven benefit in multigraft coronary artery bypass. Total ITA grafts, if reoperation is averted by avoiding saphenous vein grafts (SVGs), are attractive. The safety of the total ITA graft operation (all-ITA) is a concern.

METHODS

A randomized trial of multiple-ITA bypass graftings with the use of bilateral sequential ITA without SVGs was performed. Control patients received 1 ITA plus SVG. Inclusion criteria were those used in the Coronary Artery Surgery Study, extended to age 76 years, and any angina class, except emergent. One hundred sixty-two patients were randomized (81 patients per group) from January 1, 1990, to December 31, 1994.

RESULTS

Baseline traits were similar as were cross-clamp times, pump times, and number of arteries bypassed (average, 4.3 arteries). Patients who received multiple ITA grafts had no myocardial infarctions, per reference laboratory. One patient died, and 2 patients returned for bleeding. The ITA-SVG group had similar results. The all-ITA group experienced successful completion in 93% of cases. Complications did not differ from control patients.

CONCLUSIONS

Early and 5-year outcomes were not different between the all-ITA group and the ITA with SVGs group. We believe experienced surgeons can safely extend the ITA to multibypass coronary artery bypass without use of SVG to achieve an all-ITA operation.

Multicenter radial artery patency study (RAPS). Study design

The use of an internal thoracic artery rather than a saphenous vein graft for left anterior descending coronary artery bypass is associated with improved long-term outcome. Hence, expanded use of arterial conduits for other coronary targets has been advocated. The radial artery possesses a number of anatomic features that are technically advantageous compared with other arterial conduits. This study will determine the relative patency of the radial artery compared to the saphenous vein for right and circumflex coronary bypass. Patients with graftable multivessel coronary disease and an estimated left ventricular ejection fraction >/= 35% undergoing nonemergent primary isolated coronary bypass surgery are eligible. The right and circumflex vessels must have high-grade lesions (>/= 70% diameter stenosis), with target segments of reasonable quality >/= 1.5 mm in diameter. Patients serve as their own controls. The radial artery is randomly allocated to bypass the right or circumflex territory and a saphenous vein is used for the nonradial site. An internal thoracic artery is used for the left anterior descending coronary artery in all cases. Randomization is stratified by center. The primary study endpoint is graft patency as determined by angiography, 8-12 months postoperatively. The relative patency of the radial artery compared with the saphenous vein will be determined using McNemar's test. A sample size of 464 patients will provide 80% power for a two-tailed test (alpha = 0.05) for a 40% relative reduction in the rate of distal anastomotic occlusion from 12% in the saphenous vein to 7.2% in the radial arteries assuming a 20% within-patient correlation. A single interim analysis will be performed following completion of 232 angiograms. To allow for lack of follow-up angiography in up to 20% of enrolled patients, we plan to randomize a total of 560 patients. It is also our intention to assess the long-term patency (5-10 years) of radial artery relative to saphenous vein grafts in follow-up studies. Three hundred patients were recruited from 12 Canadian, university-affiliated sites from November 1996 until February 1999, of which 128 patients have undergone follow-up angiography. Approximately 80% of those who have been followed for more than 1 year have undergone follow-up angiography. This trial will determine the 8-12 month patency of the radial artery relative to the saphenous vein for non-left anterior descending coronary bypass using a novel study design which helps control for potential bias from individual patient and vessel factors. Positive results would support the use of the radial artery in particular, and multiple arterial grafts in general.

Bilateral skeletonized internal thoracic artery grafting in 303 patients seventy years and older

OBJECTIVES

Higher patency rates of the internal thoracic artery have led myocardial revascularization with bilateral internal thoracic arteries to be a procedure designated primarily for young patients. Fewer leg wound complications and sternal collateral flow preservation with the skeletonizing dissection technique can make bilateral internal thoracic artery grafting attractive also for elderly patients.

METHODS

Between May 1996 and May 1998, 303 consecutive patients aged 70 years or older (mean age 75.5 years; range 70-92 years) underwent coronary artery bypass grafting with double skeletonized internal thoracic arteries. Forty-four (14.5%) patients were 80 years or older, and 89 (28%) had diabetes. The mean number of grafts was 3.1 per patient (2-6).

RESULTS

Operative mortality was 2.6% (n = 8): it was higher for octogenarians (6.8%) than for younger patients (1.9%) (P =.06). The only significant preoperative predictors of early mortality were complicated percutaneous transluminal coronary angioplasty (P =.03) and preoperative use of intra-aortic balloon pumping (P =.03). Six patients (2%) had sternal wound infections for which chronic lung disease (P =.02) and emergency operation (P =.006) were the only significant predictors. Twenty-two (7.2%) late deaths occurred, and 1- and 3-year survivals were 93% and 90%, respectively. The 3-year survival of patients 80 years old or older was 92%.

CONCLUSIONS

Bilateral grafting of the skeletonized internal thoracic artery carries relatively low morbidity and mortality in elderly patients and can be recommended for selected patients including octogenarians.

[Total arterial myocardial revascularization with both mammary arteries without extracorporeal circulation]

INTRODUCTION

Tector has described the off-pump total arterial revascularization technique, using multiple anastomosis with both internal thoracic arteries. To reduce surgical morbid-mortality, we have proposed the use of this technique without extracorporeal circulation.

PATIENTS AND METHODS

From April, 1998 the off-pump <<Tector>> technique was performed in 92 patients, 74 male (80%) and 18 female (20%), with a mean age of 64.9+/-8.1 years (42-78). Preoperative angiography demonstrated triple-vessel disease in 58 (63%) patients, and left main disease was present in 19 (20.5%) patients. Forty patients (43.5%) showed unstable angina, 24 patients (26%) significant peripheral vascular disease, and 26 (28%) diabetes mellitus. Both internal thoracic arteries were harvested using the skeletonization technique and were used like a <<T or T>> graft. The flow in the graft was measured using a flowmeter, and in 24 (26%) patients by angiographic study.

RESULTS

A total of 274 distal anastomoses were performed, 122 (44.6%) in the lateral or inferior wall, and 69 (25.2%) were sequential, with an average of 2.98 bypass/patient. In 59.8% of the patients a triple bypass was performed, 22% double bypass, 17% cuadruple bypass and 1 patient a quintuple bypass. During the initial six hours 64.9% of patients were extubated. Only one patient (1.1%) needed intraaortic ballon pumping and 3 (3.2%) inotropics during the postoperative course. Hospital mortality was 3 (3.2%) patients. Reoperation for bleeding was needed in just one patient (1.1%), and 78.3% of patients were not transfused. Mediastinitis occurred in 3 patients (3.2%). Postoperative stroke was not observed. At 7.7+/-2.8 months of mean follow-up all patients were free of symptoms and the global patency rate of 94%.

CONCLUSIONS

Off-pump Tector technique appears to be safe, offering a complete arterial revascularization and showing a reduction of surgical morbidity.

Total arterial coronary revascularization: techniques and results in 3,220 patients

BACKGROUND

To overcome the problems of late vein graft atherosclerosis, occlusion and need of coronary reoperations, we have adopted a strategy of total arterial coronary revascularization. We evaluated our experience with this strategy to establish its safety and efficacy.

METHODS

All 3,220 consecutive patients who had total arterial coronary revascularization from January 1988 to June 1998 were evaluated. Data were collected prospectively. The mean age was 62.2 years. Of the patients, 595 (18.8%) had diabetes; 739 (23%) had a left ventricular ejection fraction of less than 0.50; and 484 (15%) were classified unstable/urgent. The conduits included 3,140 left internal thoracic arteries, 1,224 right internal thoracic arteries, and 2,417 radial arteries, 654 of which were bilateral. A Y or T graft with the left internal thoracic artery was used in 467 patients. Patients were followed up at 1 month, 3 months, and yearly thereafter. Postoperative angiography was performed for symptoms or as part of an ethics committee-approved prospective study.

RESULTS

The operative mortality rate was 0.7% (21 patients). Complications included stroke in 26 patients (0.8%), myocardial infarction in 27 (0.8%), sternal infection in 35 (1.1%), and reoperation for hemorrhage in 23 (0.7%). The peak level of the myocardial enzyme of creatine kinase was 16.4+/-14.9 IU/L. Twenty-five patients (0.8%) required intraoperative or postoperative intraaortic balloon pump support. Mortality and stroke rates were higher in patients having reoperation (0.6% versus 1.8%; p = 0.11; and 0.7% versus 2.2%; p = 0.07, respectively). Postoperative angiographic patency was 97% at 5 years for the left internal thoracic artery (620 grafts), 89% at 5 years for the right internal thoracic artery (276 grafts), and 91% at 1 year for the radial artery (65 grafts).

CONCLUSIONS

Total arterial coronary revascularization can be performed safely with good patency rates in a large number of patients and may potentially avoid the sequelae of vein graft atherosclerosis.

The continuing evolution of arterial conduits

Vineberg used the internal thoracic artery (ITA) to achieve indirect myocardial revascularization in 1950, and Green reported direct coronary anastomosis with an operating microscope in 1968. It was not until the early 1980s that superior 10-year patency compared with saphenous vein was established for the ITA. In 1986, Loop proved better patient survival at 10 years when the left ITA was grafted to the left anterior descending artery rather than vein in patients with triple-vessel disease having complete revascularization. Only in 1998 has Lytle shown enhanced survival with use of two ITAs over one in triple-vessel disease. This report came 4 months after a report showing no additional benefit from the second ITA. Increasingly, complex use of arterial conduits allows complete revascularization with two arterial conduits (both ITAs or one ITA and one radial artery) in most patients (with 10-year data soon to be available in the former). The T-graft configuration (ITA T-graft or radial T-graft) is highly complex and utilizes single-source inflow to the entire heart (in addition to native coronary flow), which may not provide adequate inflow and remains controversial. Although patency for the ITA is well established, this cannot be said for the radial artery (one report of 55 conduits to 5.5 years), the gastroepiploic artery (one report of 44 conduits to 7 years), or the inferior epigastric artery (one report of 154 conduits to 43 months). Long-term follow-up of each conduit and each configuration is required to prove its durability and, therefore, value in the operative management of coronary disease.

Routine use of bilateral skeletonized internal mammary arteries for myocardial revascularization

BACKGROUND

Complete arterial myocardial revascularization without the use of saphenous veins grafts was primarily performed on selected patient populations such as the young and nondiabetic. In a recently developed surgical technique, the internal mammary artery is dissected gently as a longer skeletonized artery, providing greater versatility for complete arterial revascularization, without saphenous veins grafts.

METHODS

We prospectively evaluated the impact of the routine use of double skeletonized internal mammary artery in 472 patients who underwent coronary artery bypass grafting between April 1996 and June 1997. Their average age was 65 years (30 to 87 years), 383 (83%) were men, and 89 (17%) women. One hundred sixty-nine (36%) of the patients were older than 70 years, and 145 (31%) were diabetic. The average number of grafts was 3.2 per patient (two to six grafts).

RESULTS

Operative mortality was 1.7% (n = 8). The mortality of urgent and elective patients was 0.7% (3 of 410 patients), and that of emergency operations was 8.1% (5 of 62 patients; p < 0.01). There were three (0.6%) perioperative infarcts, and 6 patients (1.3%) sustained strokes. Sternal wound infection occurred in 8 patients (1.7%). Postoperative follow-up (1 to 25 months) was available in 462 patients (99%). Two-year actuarial survival was 96.8%, and 92% of the surviving patients are well and free of angina. Neither diabetes mellitus nor old age (>70 years) were significant independent predictors of any early or late untoward events. None of the 70 diabetic patients more than 65 years of age developed sternal wound infection. Chronic lung disease was found to be the only independent predictor for sternal infections.

CONCLUSIONS

Routine use of bilateral skeletonized internal mammary artery is a safe replacement for the current myocardial revascularization technique even in the old and diabetic patients.

Total arterial revascularization with an internal thoracic artery and radial artery T graft

BACKGROUND

Proximal anastomosis of the radial artery to the side of the internal thoracic artery (ITA) permits complete arterial revascularization in most patients, with the aim of improving long-term results of coronary artery bypass through greater long-term graft patency. The short-term results, however, have yet to be defined. We therefore reviewed our early experience with this grafting strategy.

METHODS

Between October 1, 1993, and September 1, 1998, 649 patients aged 30 to 85 years (mean, 60+/-10 years) had primary coronary artery bypass using an ITA and radial artery in a T-graft configuration. Left ventricular function was severely depressed (ejection fraction <35%) in 12%, and left main stenosis was present in 14%.

RESULTS

A total of 937 distal anastomoses were performed with the left ITA (1.4 per patient) and 1,452 with the radial artery (2.2 per patient). There was one perioperative death (0.2%). There were 32 (5%) q-wave myocardial infarctions, and 14 patients (2%) had transient low output syndrome. There was one episode of hypoperfusion corrected by lengthening the left ITA. Angiography for clinical indications in 27 patients 1 to 35 months postoperatively (mean, 9.5+/-8.3 months) demonstrated a distal anastomotic patency of 100% for ITA and 82% for radial artery grafts.

CONCLUSIONS

Complete arterial revascularization can be achieved with an ITA and radial artery T-graft with low operative risk and acceptable early patency. These results support the continued investigation of this grafting strategy.

Sternal wound infections in patients after coronary artery bypass grafting using bilateral skeletonized internal mammary arteries

OBJECTIVES

This study evaluated the risks of sternal wound infections in patients undergoing myocardial revascularization using bilateral skeletonized internal mammary arteries (IMAs).

BACKGROUND

The skeletonized IMA is longer than the pedicled one, thus providing the cardiac surgeon with increased versatility for arterial myocardial revascularization without the use of vein grafts. It is isolated from the chest wall gently with scissors and silver clips, and no cauterization is employed. Preservation of collateral blood supply to the sternum and avoidance of thermal injury enable more rapid healing and decrease the risk of sternal wound infection.

METHODS

From April 1996 to August 1997, 545 patients underwent arterial myocardial revascularization using bilateral skeletonized IMAs. The right gastroepiploic artery was used in 100 patients (18%). The average age of the patients was 65 years; 431 (79%) were men and 114 (21%) were women; 179 (33%) were older than 70 years of age; 166 (30%) were diabetics. The average number of grafts was 3.2 per patient.

RESULTS

The 30-day operative mortality rate was 2% (n = 11). There were six perioperative infarcts (1.1%) and six strokes (1.1%); 9 patients had sternal infection (1.7%) and 15 (2.8%) had superficial infection. Risk factors for sternal infection were chronic obstructive pulmonary disease and emergency operation. Superficial sternal wound infections were more common in women and in patients with chronic obstructive pulmonary disease, renal failure, or peripheral vascular disease. The 1-year actuarial survival rate was 97%. Two of the six late deaths were not cardiac-related. Late dehiscence occurred in three patients (0.6%). The death rate (early and late) of patients with any sternal complication was higher than that of patients without those complications (33% vs. 2.7%).

CONCLUSIONS

Routine arterial myocardial revascularization using bilateral skeletonized IMAs is safe, and postoperative morbidity and mortality rates are low, even in elderly patients and those with diabetes. Chronic obstructive pulmonary disease and emergency operations were found to be associated with an increased risk of sternal infections, and the authors recommend avoiding the use of bilateral skeletonized IMAs in patients with these preoperative risk factors.

Inverted T graft: novel technique using composite radial and internal thoracic arteries

BACKGROUND

Multiple arterial revascularization is feasible because of the excellent long-term patency of the arterial grafts compared with venous grafts. We present a new operative technique for multiple arterial revascularization using composite radial and internal thoracic arterial grafts.

METHODS

Between January and September 1997, 12 patients had coronary artery bypass grafting with inverted T graft. The indications for inverted T graft were aortic calcification in 4 patients, repeat coronary artery bypass grafting in 1 patient, and total arterial revascularization in 7 young patients. The inverted T graft was constructed by interconnecting the coronary arteries and radial artery with end-to-side and side-to-side anastomoses, and by anastomosing the internal thoracic artery to the side of radial artery.

RESULTS

Overall, 38 distal anastomoses (average number per patient, 3.2) were made with an inverted T graft. There were no deaths or perioperative myocardial infarctions. Postoperative angiography disclosed that all of the anastomoses were patent.

CONCLUSION

This technique allows multiple arterial revascularizations without technical difficulty. It is useful in patients with aortic calcification, repeat coronary artery bypass grafting patients, and young patients who are candidates for total arterial revascularization.

Arterial grafting: techniques and conduits

The superior long-term patency and survival of the internal thoracic artery in coronary artery bypass grafting, compared with saphenous vein, established the internal thoracic artery as the conduit of choice for myocardial revascularization. Use of the internal thoracic artery has expanded, and the possibility of similar performance by other arteries has motivated surgeons to investigate alternative arterial conduits (eg, the gastroepiploic artery, inferior epigastric artery, and radial artery). Although these grafts have become more technically feasible and have shown benefits, more follow-up data are needed to determine the long-term patency, freedom from arteriosclerosis, and efficacy of alternative conduits.