Angiographic evidence for reduced graft patency due to competitive flow in composite arterial T-grafts

Personalized surgical planning for coronary bypass graft configurations using patient-specific computational modeling to avoid flow competition in arterial grafts

Objectives

Flow competition between coronary artery bypass grafts (CABG) and native coronary arteries is a significant problem affecting arterial graft patency. The objectives of this study were to compare the predictive hemodynamic flow resulting from various total arterial grafting configurations and to evaluate whether the use of computational fluid dynamics (CFD) models capable of predicting flow can assist surgeons to make better decisions for individual patients by avoiding poorly functioning grafts.

Methods

Sixteen cardiac surgeons declared their preferred CABG configuration using bilateral internal mammary and radial arteries for each of 5 patients who had differing degrees of severe triple vessel coronary disease. Surgeons selected both a preferred 'aortic' strategy, with at least one graft arising from the ascending aorta, and a preferred "anaortic" strategy which could be performed as a "no-aortic touch" operation. CT coronary angiograms of the 5 patients were coupled to CFD models using a novel flow solver "COMCAB." Twelve different CABG configurations were compared for each patient of which 4 were "aortic" and 8 were "anaortic." Surgeons then selected their preferred grafting configurations after being shown predictive hemodynamic metrics including functional assessment of stenoses (instantaneous wave-free ratio; fractional flow reserve), transit time flowmetry graft parameters (mean graft flow; pulsatility index) and myocardial perfusion.

Results

A total of 87.5% (7/8) of "anaortic" configurations compared to 25% (1/4) of "aortic" configurations led to unsatisfactory grafts in at least 1 of the 5 patients (P = 0.038). The use of the computational models led to a significant decrease in the selection of unsatisfactory grafting configurations when surgeons employed "anaortic" (21.25% (17/80) vs. 1.25% (1/80), P < 0.001) but not "aortic" techniques (5% (4/80) vs. 0% (0/80), P = 0.64). Similarly, there was an increase in the selection of ideal configurations for "anaortic" (6.25% (5/80) vs. 28.75% (23/80), P < 0.001) but not "aortic" techniques (65% (52/80) vs. 61.25% (49/80), P = 0.74). Furthermore, surgeons who planned to use more than one unique "anaortic" configuration across all 5 patients increased (12.5% (2/16) vs. 87.5% (14/16), P<0.001).

Conclusions

"COMCAB" is a promising tool to improve personalized surgical planning particularly for CABG configurations involving composite or sequential grafts which are used more frequently in anaortic operations.

Selecting the optimal treatment for left main coronary disease: The importance of identifying subgroups of patients

Randomized trials of stenting versus surgery for patients with unprotected left main (LM) coronary stenosis have largely shown similar survival between the two interventions. However, patients with LM stenosis represent a heterogeneous group in which subgroups likely to benefit from one therapy more than another are difficult to identify. Increasing coronary disease burden is the most accepted subgrouping for identifying optimal therapy but this can be defined in more detail allowing greater discrimination. Competitive flow reduces bypass graft patency in patients with isolated LM stenosis and complex bifurcation stenoses reduce the effectiveness of coronary stenting. The evidence for LM stenosis subgroupings is presented.

Additional survival benefit of bilateral in situ internal thoracic artery grafting with composite radial artery graft in total arterial off-pump coronary artery bypass grafting

OBJECTIVE

This study aimed to elucidate whether the use of bilateral internal thoracic arteries (BITAs) confers additional survival benefits compared with a single internal thoracic artery (SITA) in total arterial grafting with the radial artery.

METHODS

Between 2002 and 2016, 617 patients underwent a bilateral in situ internal thoracic artery grafting with the radial artery as a composite I-graft (BITA-I group) and 516 patients underwent single in situ internal thoracic artery grafting with the radial artery as a composite Y-graft (SITA-Y group). All anastomoses were performed without cardiopulmonary bypass and aortic manipulation. Propensity score matching was performed to adjust covariates and compared the outcomes between the 2 groups. Subanalysis was also performed to evaluate the effects of the BITA-I group on survival according to the covariates using Cox proportional hazards regression analysis.

RESULTS

Propensity score matching yielded 348 well-matched pairs. Early postoperative outcomes were similar in the 2 groups. The BITA-I group showed significantly better survival than the SITA-Y group (79.3% vs 70.2% at 10 years, P = .015). The subanalysis revealed a significantly better survival in the BITA-I group among overall patients (hazard ratio, 0.68; 95% confidence interval, 0.49-0.93). There was a significant positive effect on survival in the BITA-I group among patients without comorbidities or those aged <77 years.

CONCLUSIONS

BITA grafting with the radial artery provides better long-term survival than SITA grafting with the radial artery, which is enhanced among patients aged <77 years with minimum comorbidities.

The Growth Potential and Patency of Free Right Internal Thoracic Arteries Verified by Computed Tomography Angiography

BACKGROUND

The use of the left internal thoracic artery (LITA) is the gold standard in coronary artery bypass graft surgery (CABG). Multiarterial grafting for CABG is being increasingly emphasized. This study aimed to resolve the utility of the right internal thoracic artery (RITA) for multiple CABG as "free" RITA and described new evidence.

METHODS

One hundred sixty-three patients received solo CABG with bilateral internal thoracic arteries between 2005 and 2018. The RITA was used as in situ RITA, group A (n = 62), and the composite graft created with saphenous vein graft (SVG), group B (n = 101). The patency rate and graft size of the composite free RITA and SVG were examined by coronary computed tomography angiography.

RESULTS

The average number of distal anastomoses per patient was 3.4 ± 1.0 in group A, and 4.2 ± 1.1 in group B (P < .001). The sequential grafting with free RITA was in 86 patients. The patency rate of both LITA and RITA was similar in both groups. In group B, 40 patients received late computed tomography angiography at a mean of 46 months (range, 17 to 175). The late patency rate was 95.1% in LITA and 96.9% in free RITA. The diameter of free RITA increased from 2.06 ± 0.34 mm to 2.37 ± 0.23 mm (P = .036); that of in situ LITA increased from 2.08 ± 0.51 mm to 2.44 ± 0.49 mm (P = .047); and that of composite SVG decreased from 4.1 ± 0.9 mm to 2.6 ± 0.7 mm (P < .001).

CONCLUSIONS

Multiple bypass grafting can be sufficiently achieved with LITA and free RITA. The growth potential of free RITA and in situ LITA might play the important role of expected long-term patency.

The role of fractional flow reserve in coronary artery bypass graft surgery: a meta-analysis

OBJECTIVES

Fractional flow reserve (FFR) measures the drop in perfusion pressure across a stenosis, therefore representing its physiological effect on myocardial blood flow. Its use is widespread in percutaneous coronary interventions, though its role in coronary artery bypass graft (CABG) surgery remains uncertain. This systematic review and meta-analysis aims to evaluate current evidence on outcomes following FFR-guided CABG compared to angiography-guided CABG.

METHODS

A literature search was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to identify all relevant articles. Patient demographics and characteristics were extracted. The following outcomes were analysed: repeat revascularization, myocardial infarction (MI) and all-cause mortality. Pooled relative risks were analysed and their 95% confidence intervals (CIs) were estimated using random-effects models; P-value <0.05 was considered statistically significant. Heterogeneity was assessed with Cochran's Q score and quantified by I2 index.

RESULTS

Nine studies with 1146 patients (FFR: 574, angiography: 572) were included. There was no difference in MI or repeat revascularization between the 2 groups (relative risk 0.76, 95% CI 0.41-1.43; P = 0.40, and relative risk 1.28, 95% CI 0.75-2.19; P = 0.36, respectively). There was a significant reduction in all-cause mortality in the FFR-guided CABG group compared to angiography-guided CABG, which was not specifically cardiac related (relative risk 0.58, 95% CI 0.38-0.90; P = 0.02).

CONCLUSIONS

There was no reduction in repeat revascularization or postoperative MI with FFR. In this fairly small cohort, FFR-guided CABG provided a reduction in mortality, but this was not reported to be due to cardiac causes. There may be a role for FFR in CABG, but large-scale randomized trials are required to establish its value.

Are two internal thoracic grafts better than one in patients with peripheral vascular disease?

BACKGROUND

The use of two bilateral internal thoracic artery grafting (BITA) was shown to lead to survival benefit. However, operators are reluctant to use BITA with peripheral vascular disease (PVD) because of concerns of increased rates of sternal wound infection and lack of studies supporting survival benefit compared with single internal thoracic artery (SITA) grafting. The aim of this study is to compare outcome BITA grafting versus of SITA and vein grafts in PVD patients.

PATIENTS AND METHODS

Six hundred and twenty-one PVD patients who underwent BITA between 1996 and 2011 were compared with 372 patients who underwent SITA.

RESULTS

SITA patients were older and more likely more likely to have comorbidities (female, insulin-dependent diabetes, chronic obstructive lung disease, congestive heart failure, previous coronary artery bypass grafting, renal insufficiency, cerebrovascular disease, and emergency operation). Operative mortality (5.1 vs. 4.5%, in the SITA and BITA, respectively, P=0.758), rate of sternal wound infection (5.1 vs. 3.9%, P=0.421), and strokes (4.8 vs. 7.4%, P=0.141) were not significantly different between groups. BITA patients did not have significantly better 10-year survival (52.6 vs. 45.9%, P=0.087) and after propensity score matching (302 well-matched pairs), BITA was not associated with improved survival (hazard ratio: 0.902; 95% confidence interval: 0.742-1.283; P=0.784) (Cox model).

CONCLUSION

The routine use of BITA versus SITA in PVD patients does not improve long-term survival. Selective use of BITA in lower risk patients might unmask the benefits of BITA.

Optimal target vessel selection for composite and sequential radial artery grafting with an in situ internal thoracic artery

OBJECTIVES

We retrospectively evaluated graft patency in patients who underwent no-touch aortic arterial off-pump coronary artery bypass grafting to determine the optimal selection of target vessels for improved graft patency of composite and sequential radial artery I-grafts.

METHODS

The radial artery was anastomosed to the end of an in situ internal thoracic artery and was sequentially anastomosed to non-left anterior descending arteries. This composite graft was defined as an "I-graft." We evaluated 145 I-grafts with 2, 3, or 4 sequential anastomoses (437 graft segments). A graft segment with the final distal anastomosis of every I-graft was defined as the last graft segment (LGS). When a sequential anastomosis was initiated from the left coronary branch, the I-graft assumed a clockwise course (69.0%). When a sequential anastomosis was initiated from the right coronary branch, the I-graft assumed a counterclockwise course (31.0%).

RESULTS

On multivariable analysis, right coronary branch (P < 0.001), moderately stenotic (50-75%) target vessel (P = 0.004), and LGS with moderately stenotic target vessel (P = 0.005) were predictors of mid-term graft occlusion. In situations where the LGS was anastomosed to a severely stenotic target vessel (>75%) with a clockwise course, when the number of moderately stenotic target vessels among sequential graft segments was 0, 1, or ≥2, the mid-term graft patency rates of I-grafts were 94.0%, 86.0%, and 81.4%, respectively.

CONCLUSIONS

The selection of target vessels for severely stenotic lesions among sequential graft segments and the clockwise course enhance the mid-term graft patency of sequential radial I-grafts.

Should Bilateral Internal Thoracic Artery Grafting Be Used in Patients After Recent Myocardial Infarction?

Background

Bilateral internal thoracic artery grafting (BITA) is associated with improved survival. However, surgeons do not commonly use BITA in patients after myocardial infarction (MI) because survival is good with single internal thoracic artery grafting (SITA). We aimed to compare the outcomes of BITA with those of SITA and other approaches in patients with multivessel disease after recent MI.

Methods and Results

In total, 938 patients with recent MI (<3 months) who underwent BITA between 1996 and 2011 were compared with 682 who underwent SITA. SITA patients were older and more likely to have comorbidities (diabetes mellitus, chronic obstructive pulmonary disease, chronic renal failure, peripheral vascular disease), to be female, and to have had a previous MI. Acute MI and 3‐vessel disease were more prevalent in the BITA group. Operative mortality of BITA patients was lower (3.0% versus 5.8%, P=0.01), and sternal infections and strokes were similar. Median follow‐up was 15.21 years (range: 0–21.25 years). Survival of BITA patients was better (70.3% versus 52.5%, P<0.001). Propensity score matching was used to account for differences in preoperative characteristics between groups. Overall, 551 matched pairs had similar preoperative characteristics. BITA was a predictor of better survival in the matched groups (hazard ratio: 0.679; P=0.002; Cox model). Adjusted survival of emergency BITA and SITA patients was similar (hazard ratio: 0.883; P=0.447); however, in the nonemergency group, BITA was a predictor of better survival (hazard ratio: 0.790; P=0.009; Cox model).

Conclusions

This study suggests that survival is better with BITA compared with SITA in nonemergency cases after recent MI, with proper patient selection.

Comparison of radial and bilateral internal thoracic artery grafting in patients with peripheral vascular disease†

OBJECTIVES

The composite T-graft with radial artery (RA) attached end-to-side to the left internal thoracic artery (ITA) provides arterial myocardial revascularization without the increased risk of deep sternal wound infection associated with harvesting 2 ITAs. However, many surgeons are reluctant to use RA in patients with peripheral vascular disease (PVD) due to concerns regarding the quality of the conduit in this subset of patients. The purpose of this study is to compare early- and long-term outcomes of arterial grafting with bilateral ITAs (BITA) to that of single ITA and RA in patients with PVD.

METHODS

Between 1999 and 2010, 619 consecutive patients with PVD (500 BITAs and 119 single ITA and RA) underwent myocardial revascularization in our institution.

RESULTS

Occurrence of following risk factors as female sex, age 70+, diabetes, unstable angina, emergency operation, cerebrovascular disease and chronic obstructive pulmonary disease was higher in the RA-ITA group. The RA-ITA group also had a higher logistic EuroSCORE (22.1 vs 13.3). Operative mortality and occurrence of deep sternal wound infection of the two groups was similar (4.2% vs 5.0% and 2.5% vs 4.0% for the radial and bilateral ITA, respectively). Median follow-up was 9.75 years. Unadjusted Kaplan-Meier 10-year survival of the two groups was similar (44.1% vs 49.6%, P  = 0.7). After propensity score matching (100 pairs), assignment to BITA was not associated with better adjusted survival (hazard ratio 0.593, 95% confidence interval 0.265-1.327, P  = 0.20, Cox model).

CONCLUSIONS

In patients with PVD, complete arterial revascularization with left ITA and RA can be justified with regards to survival.

Composite Y-Grafting Using the Left Internal Thoracic Artery: Survival and Angiography in 198 Cases

BACKGROUND

Extended left internal thoracic artery (LITA) harvesting allows maximal grafting to the anterior and lateral walls with a single ITA conduit. This study evaluates outcomes following the use of a LITA Y graft as the primary grafting strategy.

METHODS

Patients who underwent LITA composite Y-grafting (n=198) between 1995 and 2009 were identified from a cardiac surgical database. Follow-up (mean 13.1 years) was obtained by cross-reference with the state death registry and local cardiology databases.

RESULTS

Operative mortality was zero in the 168 patients who underwent isolated CABG and was 3.5% overall. There were no episodes of perioperative myocardial infarction. Kaplan-Meier 10-year survival was 75.9%. Independent predictors of worse late survival were age, diabetes, chronic obstructive pulmonary disease and pre-existing left ventricular dysfunction. There were 53 episodes of post-discharge angiography at an average of 5.8 years post LITA Y grafting. Twenty cases of LITA Y graft failure were identified, predominantly affecting the free limb (n=15). The ratio of symptom driven angiography to Y graft failure increased over time. Eighteen patients required revascularisation, percutaneous intervention in 15 and reoperative coronary bypass in three.

CONCLUSIONS

Left Internal Thoracic Artery Y grafting is a feasible revascularisation strategy with satisfactory outcomes. These are comparable to other arterial composite graft configurations. A LITA Y allows efficient conduit use without compromising the in situ LITA graft.

Long-term outcome of revascularization with composite T-grafts: Is bilateral mammary grafting better than single mammary and radial artery grafting?

OBJECTIVE

Bilateral internal mammary artery (BIMA) grafting is associated with improved survival. However, many surgeons are reluctant to use this technique, owing to the potentially increased risk of sternal infection. The composite T-graft with radial artery (RA) attached end-to-side to the left internal mammary artery (IMA) provides complete arterial revascularization without increased risk of sternal infection. The purpose of this study is to compare outcomes of these 2 strategies.

METHODS

Patients who underwent BIMA grafting using the composite T-graft technique, between 1996 and 2010 (n = 1329), were compared with 389 patients who underwent composite grafting with a single IMA + RA during the same time period.

RESULTS

Patients undergoing single IMA grafting were older, more often women, and more likely to have diabetes, peripheral vascular disease, and COPD, and to need an emergency operation. Congestive heart failure, left main disease, and recent myocardial infarction were more prevalent with bilateral grafting. Propensity-score matching was used to account for differences between groups in preoperative patient characteristics. The 268 matched pairs had similar characteristics. The median follow-up time was 14.19 (95% confidence interval 13.43-14.95) years. Operative mortality and Kaplan-Meier 10-year survival of the 2 matched groups were similar (3.4% vs 3.7%, and 61.6% vs 64%, for the groups treated with BIMA and single IMA, respectively). Cox-adjusted survival was similar (P = .514). Age, chronic renal failure, and performance of <3 bypass grafts were independent predictors of decreased survival.

CONCLUSIONS

This study suggests that long-term outcomes of arterial revascularization with a composite T-graft constructed using left IMA and RA are not inferior to outcomes after BIMA grafting.

V-composite grafting using the right internal thoracic artery grafts anastomosed to aorto-coronary bypass grafts

OBJECTIVES

Composite grafting using the right internal thoracic artery (RITA) is occasionally performed when the in situ RITA does not have sufficient length to reach the target vessel. In this study, we assessed the clinical and angiographic outcomes of coronary artery bypass grafting (CABG) with V-composite grafting (defined as a distance between the proximal anastomosis of the RITA and the ascending aorta of ≤1 cm) using the RITA anastomosed to aortocoronary (A-C) bypass grafts.

METHODS

Between September 2004 and December 2012, 177 patients underwent CABG with V-composite grafting using the RITA and the A-C bypass graft [radial artery (RA) or saphenous vein graft (SVG)] at our institution. The mean age was 69.2 ± 8.5 years and 149 (84.2%) were men. The clinical outcomes and patency rates of distal anastomoses of the composite RITA were retrospectively evaluated.

RESULTS

Mean distal anastomoses per patient were 4.6 ± 1.0, and mean distal anastomoses of the RITA per patient were 1.3 ± 0.5. Inflow conduit of the RITA was the RA in 16 (9.0%) patients and an SVG in 161 (91.0%) patients. The 30-day mortality rate was 1.1% (2/177). The overall patency rate of distal anastomoses of the composite RITA on early (before discharge) and follow-up (at 1 year) angiography was 97.6 and 93.6%, respectively. The inflow conduit (RA or SVG), stenosis grade of target vessel and sequential grafting did not affect the patency rate of the composite RITA.

CONCLUSIONS

V-composite grafting using the RITA and the A-C bypass graft provides excellent clinical outcomes with satisfactory early and 1-year patency rates.

Long-term outcomes of coronary artery bypass grafting patients supported preoperatively with an intra-aortic balloon pump

OBJECTIVE

Most studies describing the outcome of coronary artery bypass grafting patients supported preoperatively with an intra-aortic balloon pump (IABP) have reported early results. The purpose of our study was to evaluate the early and long-term results.

METHODS

Of 2658 isolated coronary artery bypass grafting procedures performed from 1996 to 2001, 215 were supported preoperatively with an IABP. The indications for IABP insertion were cardiogenic shock in 18 (8.4%), acute evolving myocardial infarction in 38 (17.7%), clinical instability in 84 (39.1%), and critical coronary lesions in 75 (34.9%).

RESULTS

Operative mortality was 12.6%. The mortality of the cardiogenic shock patients was greater (22.2%; P=.174). Logistic regression analysis showed patient age (odds ratio, 1.057; 95% confidence interval, 1.010-1.108) and cardiopulmonary bypass (CPB) time (odds ratio, 1.020; 95% confidence interval, 1.008-1.031) were associated with increased operative mortality. An increased number of bypass grafts had a protective effect (odds ratio, 0.241; 95% confidence interval, 0.113-0.515). The actual early mortality was lower than the logistic EuroSCORE calculated mortality (12.6% vs 32.8%, P<.0001). The mean follow-up was 8±4 years. The Kaplan-Meier 10-year survival was 49%. The Cox adjusted overall (early and late) survival and major adverse cardiac events-free survival of the different IABP subgroups was similar. Cox analyses showed peripheral vascular disease, off-pump coronary artery bypass surgery, age, CPB time, female gender, and fewer bypass grafts were associated with decreased survival.

CONCLUSIONS

In patients supported preoperatively with an IABP, better early and long-term results were strongly related to younger age, a shorter CPB time, and a greater number of bypass grafts. Avoiding the use of CPB (off pump) in these emergency cases is not recommended.

Comparison of Radial Artery and Saphenous Vein Composite Y Grafts during Off-pump Coronary Artery Bypass

Background

The safety and efficacy of arterial composite grafts for total arterial revascularization have been demonstrated. The saphenous vein (SV) is a widely used graft because of its accessibility, sufficient length, and ease of manipulation. Our aim was to compare mid-term outcomes of saphenous vein Y-grafts with radial artery Y-grafts joined by anastomosis to the left internal thoracic artery.

Materials and Methods

Records of off-pump coronary artery bypass grafting with composite Y-grafts based on the left internal thoracic artery technique in 552 patients were analyzed retrospectively. After propensity score matching, 79 radial arterial (RA) composite grafts (RA group) and 79 saphenous vein composite grafts (SV group) were compared. The duration of mean follow-up was 24.6±14.6 months (range, 1 to 55 months).

Results

There were no differences in surgical mortality, all-cause mortality, or morbidity among the groups. Rates of 4-year survival were 91.7% and 96.3% in the RA and SV groups, respectively (p=0.519). The coronary reintervention-free survival rate and freedom from major adverse cardiovascular or cerebrovascular events were similar in the two groups (p=0.685, p=0.564).

Conclusion

Construction of composite Y-grafts using the radial artery or saphenous vein showed similar mid-term results. Long-term follow-up and randomized trials will be needed to confirm our present conclusions.

Off-pump coronary artery bypass grafting using skeletonized in situ arterial grafts

Skeletonization is an advanced technique of graft harvesting for coronary artery bypass grafting (CABG), and while it requires meticulous attention, it has many advantages. For example, skeletonization of internal thoracic artery (ITA) can minimize sternal ischemia and lower the risk of mediastinitis, and is longer and larger than pedicled ITA. In this article we describe the surgical techniques demonstrated in our video, which details our techniques of skeletonization of arterial grafts and off-pump coronary artery bypass (OPCAB) exclusively using these in situ grafts. Our method of right gastroepiploic artery (GEA) skeletonization has only three technical steps. The first step is to pass thin vessel loops under the GEA. The second step is to unroof the tissue surrounding the GEA. The last step is to seal and sever all the branches. Skeletonization of the GEA not only prevents vasospasm but also leads to GEA dilatation, and facilitates inspection and makes sequential anastomosis easier. Bilateral use of the skeletonized ITA and use of the skeletonized GEA can cover most coronary artery target sites without any manipulation of the ascending aorta. In our consecutive series of over 1,000 patients, the stroke rate was 0.5%. Our method helps to make the technique simple and secure in this technically demanding operation, and we believe that OPCAB with these grafts provides the best possible coronary revascularization.

Simple adaptations of surgical technique to critically reduce the risk of postoperative sternal complications in patients receiving bilateral internal thoracic arteries

OBJECTIVES

Limited blood supply to the thoracic chest wall is a known risk factor for sternal wound complications after CABG. Therefore, bilateral internal thoracic arteries are still rarely utilized despite their proven superior graft patency. The aim of our study was to analyse whether modification of the surgical technique is able to limit the risk of sternal wound complications in patients receiving bilateral internal thoracic artery grafting.

METHODS

All 418 non-emergent CABG patients receiving bilateral internal thoracic artery CABG procedures (BITA) from January 2001 to January 2012 were analysed for sternal wound complications. Surgical technique together with known risk factors and relevant comorbidity were analysed for their effect on the occurrence of sternal wound complications by means of multivariate logistic regression analysis.

RESULTS

Sternal wound complications occurred in 25 patients (5.9%), with a sternal dehiscence rate of 2.4% (10 patients). In multivariate analysis, diabetes (odds ratio [OR]: 4.8, 95% CI: 1.9-11.7, P=0.001), but not obesity (OR: 1.6, 95% CI: 0.7-4.2, P=0.28) or chronic obstructive pulmonary disease (OR: 2.2, 95% CI: 0.87-5.6, P=0.1) was a relevant comorbid condition for sternal complications. Skeletonization of ITA grafts (OR: 0.17, 95% CI: 0.06-0.5, P=0.001) and the augmented use of sternal wires (OR: 0.24, 95% CI: 0.06-0.95, P=0.04) were highly effective in preventing sternal complications. The use of platelet-enriched-fibrin glue (PRF) sealant, however, was associated with more superficial sternal infections (OR: 3.7, 95% CI: 1.3-10.5, P=0.02).

CONCLUSIONS

Adjusted for common risk factors, skeletonization of BITA grafts together with augmented sternal wires is effective in preventing sternal complications. The use of PRF sealant, however, increased the risk for superficial wound complications.

Competitive flow in coronary bypass surgery: is it a problem?

PURPOSE OF REVIEW

Competition flow is a common finding in arterial grafting. This phenomenon can lead to graft occlusion.

RECENT FINDINGS

Internal thoracic arteries are the best equipped arterial conduit to withstand the competition flow thanks to their endothelial function. Radial as well as right gastroepiploic arteries support much less flow competition because of their different anatomy, histology and endothelial function than that of internal thoracic artery, leading to spasm and occlusion. Therefore, these two arterial conduits should be used only in case of critical lesion to avoid graft occlusion. Saphenous vein graft is the only conduit that is not significantly affected by flow competition, mainly because of its nonresistivity and common reimplantation in the aorta. Graft configuration is the second important factor influencing the equation between graft flow and native coronary flow. Therefore, composite grafting should be reserved for the case of severely stenotic coronary target, especially if multiple arterial sequential anastomoses have to be performed on the lateral-inferior wall of the heart. Finally, an accurate tool such as the fractional flow reserve to evaluate the stenosis severity should be the milestone of coronary surgery in order to decrease the rate of flow competition and improve arterial grafting functionality.

CONCLUSION

Competition flow plays a crucial role in arterial grafting functionality. Grafting strategy should address this by appropriate graft choice and configuration in order to avoid graft attrition.

Impact of competitive flow on hemodynamics in coronary surgery: numerical study of ITA-LAD model

Competitive flow from native coronary artery is considered as a major factor in the failure of the coronary artery bypass grafts. However, the physiological effects are not very clear. The aim is to research the impact of competitive flow caused by different left anterior descending (LAD) artery stenosis degrees on hemodynamics in internal thoracic artery (ITA) bypass graft. An idealized ITA-LAD model was built in CAD tools. The degree of the competitive flow was divided into five classes according to different LAD stenosis degrees: higher (no stenosis), secondary (30% stenosis), reduced (50% stenosis), lower (75% stenosis) and no competitive flow (fully stenosis). Finite volume method was employed for the numerical simulation. The flow velocity distributions, wall shear stress and oscillatory shear index were analyzed. Results showed that higher competitive flow in the bypass graft would produce unbeneficial wall shear stress distribution associating with endothelial dysfunction and subsequent graft failure. The coronary bypass graft surgery was preferred to be carried out when the LAD stenosis was higher than 75%.

Is the mid-term outcome of free right internal thoracic artery with a proximal anastomosis modification inferior to in situ right internal thoracic artery?

BACKGROUND

We investigated the mid-term results of free right internal thoracic artery (RITA) grafts used in an aorto-coronary fashion with a modified proximal anastomosis.

METHODS

The subjects were 214 patients who underwent coronary artery bypass grafting with anastomosis to the left circumflex arteries using the RITA as a free graft (Group A: 158 patients) or an in situ graft (Group B: 56 patients). In Group A, the proximal end of the free RITA was anastomosed onto the ascending aorta interposing free graft tissue or to part of its own tissue as a cuff.

RESULTS

The number of RITA anastomoses was 1.38 ± 0.50 in Group A and 1.04 ± 0.19 in Group B (P < 0.001). The relationship between perioperative variables and mid-term outcomes was assessed using Cox proportional hazard models. Survival was not associated with the way the RITA graft was performed (Hazard Ratio 5.26, 95 % CI 0.52-53.1, P = 0.159), however, the number of cardiac events was decreased in Group A (Hazard Ratio 2.55, 95 % CI 1.03-6.33, P = 0.043). The graft patency was evaluated in 187 of 214 patients, and at 1, 3 and 5 years was 97.0, 97.0 and 97.0 % in Group A, and 97.9, 92.5 and 80.5 % in Group B (P = 0.378), respectively.

CONCLUSION

By modifying the proximal anastomosis of the free RITA, cardiac events may be decreased, while survival and graft patency comparable with in situ RITA can be obtained, and a significantly larger number of targets can be revascularized.

Computerized tomography may underestimate the patency of internal thoracic artery composite grafts

BACKGROUND

Multidetector-row computerized tomography (MDCT) has been regarded as useful for noninvasive assessment of the bypass grafts after coronary artery bypass grafting (CABG), but there have been few reports validating its accuracy in assessment of composite arterial graft patency.

METHODS

In 108 patients who underwent CABG with a Y-composite graft made of bilateral internal thoracic arteries (ITAs), early postoperative (mean interval, 4.9 months) MDCT findings were compared with the findings of subsequent conventional coronary angiography (19 patients, mean 4.7 months after initial MDCT) or later MDCT (89 patients, mean 31.0 months after surgery). A total of 248 grafts with 409 distal anastomoses (mean 3.8/patient) were assessed.

RESULTS

In the early MDCT, the left ITA was patent in 94.4%. The right ITA with multiple sequential anastomoses was completely patent in 73.8% and partially patent in 21.4%. Discrepancy of findings between early computed tomography (CT) and later imaging studies was found in 18 patients (16.7%). Fourteen (42.4%, 4 left and 10 right ITAs) among the 33 initially nonvisualized grafts showed improved patency in later MDCT or conventional angiogram. The positive predictive value of the early MDCT for ITA composite graft occlusion was calculated at 57.6% or lower, whereas the negative predictive value was 97.8% or higher.

CONCLUSIONS

For a composite graft made of bilateral ITAs, especially for those with multiple sequential anastomoses, MDCT may reflect only the functional patency and underestimate the actual anatomic patency.

Bilateral Internal Thoracic Artery Grafting Current State of the Art

The purpose of this article is to review the key literature and assess the current status of bilateral internal thoracic artery grafting. Numerous retrospective studies have demonstrated a benefit of bilateral internal thoracic artery grafting over single internal thoracic artery grafting in terms of the long-term risk of all-cause death, cardiac-related death, and cardiac events. The survival benefit of bilateral internal thoracic artery grafting manifests relatively early after operation for high-risk patients. The skeletonization technique reduces the risk of sternal wound complications in all patients and particularly in those with diabetes. Both the left and right internal thoracic arteries have better patency when grated to the left coronary territory than saphenous vein. However, the right internal thoracic artery does not always have good patency when grafted to the right coronary artery. Bilateral internal thoracic artery grafting using the skeletonization technique is recommended for revascularization of the left coronary territory.

Comparison of fractional flow reserve of composite Y-grafts with saphenous vein or right internal thoracic arteries

BACKGROUND

Composite Y-grafts, using the left internal thoracic artery as the inflow, allow a more efficient use of conduits without the need to touch a diseased ascending aorta. Among other conduits, the saphenous vein graft may be an alternative to the radial artery in elderly patients.

PATIENTS AND METHODS

We evaluated the hemodynamic characteristics of 17 composite Y-grafts made with the left internal thoracic artery anastomosed to the left anterior descending coronary artery in all cases and with either the free right internal thoracic artery (RITA group, n = 10) or a saphenous vein graft (SVG group, n = 7) implanted proximally to the left internal thoracic artery and distally to the circumflex territory 6 months after the operation.

RESULTS

At baseline, the pressure gradient measured with a 0.014-inch pressure wire was minimal between the aorta and the internal thoracic artery stem (2 +/- 1 mm Hg), the internal thoracic artery and left anterior descending (4 +/- 2 mm Hg), the internal thoracic artery and left circumflex (3 +/- 1 mm Hg), and the saphenous vein graft and left circumflex (2 +/- 2 mm Hg). During hyperemia induced by adenosine, the pressure gradient increased significantly to 6 +/- 2 mm Hg in the internal thoracic artery stem, 9 +/- 4 mm Hg in the internal thoracic artery and left anterior descending artery, 9 +/- 3 mm Hg in the internal thoracic artery and left circumflex, and 7 +/- 4 mm Hg in the saphenous vein graft and left circumflex. Fractional flow reserve was 0.94 +/- 0.02 in internal thoracic artery stem, 0.90 +/- 0.04 mm Hg in the internal thoracic artery and left anterior descending, 0.91 +/- 0.03 mm Hg in the internal thoracic artery and left circumflex, and 0.92 +/- 0.06 mm Hg in the saphenous vein graft and left circumflex. No difference between the two types of composite Y-grafts was observed for pressure gradients or fractional flow reserve measured in internal thoracic artery stem or in distal branches.

CONCLUSIONS

Composite Y-grafts with saphenous vein or right internal thoracic arteries allow similar and adequate reperfusion of the left system with minimal resistance to maximal flow and an even distribution of flow in both distal branches.

Impact of purely internal thoracic artery T-graft technique on the mode and quality of surgical myocardial revascularization evaluated by early postoperative coronary angiography

BACKGROUND

The use of the internal thoracic artery for coronary artery bypass has improved the results of such surgery. However, bypass using only the internal thoracic arteries sometimes requires a T-graft. This purely internal thoracic artery T-graft technique has progressively become part of our surgical protocol for coronary artery bypass surgery.

AIMS

The aim of the study was to analyse the impact of this surgical technique on the degree and quality of coronary revascularization using early postoperative angiography.

METHODS

Between January 2004 and December 2006, 148 patients underwent coronary artery bypass surgery exclusively using both internal thoracic arteries in a T-graft configuration. Systematic postoperative angiography was offered to all 148 patients; it was accepted by 108 patients and refused by 40 patients.

RESULTS

There were no statistically significant differences between the two groups. In-patient mortality was 2.02% (n=3) for the whole population studied, and 1.49% (n=2) for the 134 patients who received only coronary artery bypass grafts. The revascularization rate was 89% and 3.46 coronary anastomoses were constructed per patient (range 2-6). Angiography was performed on 108 right internal thoracic artery to left internal thoracic artery anastomoses, 374 anastomoses of internal thoracic arteries to coronary arteries and 382 inter-anastomosis segments: 98% of the anastomoses and segments were patent.

CONCLUSION

The exclusive recourse to the purely internal thoracic artery T-graft technique meant that it has been possible to dispense with other types of graft while achieving complete and effective revascularization of the coronary artery.

Four-year outcome of OPCAB no-touch with total arterial Y-graft: making the best treatment a daily practice

BACKGROUND

A retrospective, single-center 4-year clinical study of the off-pump coronary artery bypass grafting no-touch technique with arterial conduits (Y-graft) was compared with the Syntax trial.

METHODS

Four hundred consecutive patients ("all-comers") who underwent coronary surgery between 2004 and 2008 at the Thorax Center Twente (TCT) formed the study group. The primary end point was in-hospital and 12-month major cardiovascular or cerebrovascular event (MACCE). Event rates of MACCE were based on life tables, and overall MACCE was determined by Kaplan-Meier analysis.

RESULTS

In-hospital mortality was 0.2%. Cumulative 1-year survival was 98.2%, and freedom from MACCE was 94.7% +/- 1.1%. Cumulative 4-year survival and freedom from MACCE were 91.2% +/- 2.4% and 82.1% +/- 3.0%, respectively. There were no significant differences in the baseline characteristics between the patients of the TCT group and the surgical arm of the Syntax trial. Repeat revascularization, MACCE, and symptomatic graft occlusion in the TCT group were significantly lower than in the Syntax trial. The event rate of myocardial infarction and all-cause death in the TCT group were significantly lower than those of the percutaneous coronary intervention arm of the Syntax trial. There was a clear trend toward a reduction of the event rate of stroke in the TCT group (0.8%) compared with the surgical arm of the Syntax trial (2.2%). There was no significant difference of stroke rate between the TCT group and the percutaneous coronary intervention arm of the Syntax trial.

CONCLUSIONS

A state-of-the-art surgical technique such as off-pump coronary artery bypass grafting no-touch can further improve the advantage of surgical treatment with respect to percutaneous coronary intervention. Off-pump coronary artery bypass grafting no-touch surgery can be the treatment of choice for patients with three-vessel disease and left main stenosis.

Y grafting for coronary artery bypass: is it as good as single grafting?

PURPOSE OF REVIEW

The use of multiple arterial grafting has gained popularity in recent years due to its clinical advantages when compared with conventional CABG surgery. The purpose of the present review is to focus in particular on the safety and efficacy of composite Y grafting in coronary surgery.

RECENT FINDINGS

Several studies demonstrated mid-term and long-term benefits of total arterial myocardial revascularization when compared with conventional CABG, that is utilizing the left internal mammary artery and multiple veins. Nevertheless, there have been concerns whether it is safe to have a single inflow rather than multiple aorto-coronary grafts. There is evidence in literature that composite arterial grafting is nowadays a well established technique, and several configurations can be performed according to the specific patients' needs. Moreover, the use of Y grafting completely avoids aortic manipulation, especially when used in association with the off-pump technique.

SUMMARY

Composite Y grafting with the exclusive use of arterial conduits is a well tolerated and effective technique. The choice of the second arterial conduit should be tailored according to the specific patients' characteristics. The association of composite arterial grafting and off-pump technique allows a no-touch technique of the ascending aorta, thereby also minimizing the risk of neurological events.

Total arterial revascularization in triple-vessel disease with off-pump and aortic no-touch technique

BACKGROUND

We evaluated the outcomes in patients who have undergone total arterial revascularization using the bilateral internal thoracic arteries (BITA) with off-pump and aorta no-touch technique.

METHODS

From March 2001 to September 2007, 512 consecutive patients with triple-vessel disease underwent total arterial revascularization with off-pump and aortic no-touch technique, using BITA or the right gastroepiploic artery (RGEA) in addition to BITA. Only BITA grafts were used for bypass to coronary arteries in 353 patients, and additionally in situ RGEA was bypassed to right coronary arteries in 159 patients. The mean number of distal anastomoses was 4.15 +/- 0.8 per patient.

RESULTS

One 30-day death occurred. Deep sternal wound infection occurred in 2 patients. The rate of perioperative stroke was 0.8%. The patients were followed for as long as 6 years (mean follow-up, 37.9 +/- 17.7 months). The 1-year and 5-year actuarial freedom from cardiac death was 98.3% and 96.7%, respectively. The 1-year and 5-year actuarial freedom from cardiac events was 97.1% and 89.3%, respectively. Using RGEA was a significant predictor of cardiac event-free survival (p = 0.046).

CONCLUSIONS

Total arterial revascularization using off-pump coronary bypass and aortic no-touch techniqe with BITA grafts was safe and effective, with low mortality among patients with triple-vessel disease. Patients undergoing in-situ RGEA grafting for right coronary arteries appeared to have fewer cardiac events than did patients undergoing only BITA grafting in triple-vessel disease.

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.