Long-term follow-up after coronary artery bypass grafting reoperation

Drug-Eluting Stents Versus Bare Metal Stents in Saphenous Vein Graft Intervention

Percutaneous coronary intervention (PCI) of saphenous vein graft (SVG) is associated with higher adverse event rates, lower procedural success, and inferior longterm patency rates compared with native vessel PCI. The ability to comply with dual antiplatelet therapy, and whether the patient will need an interruption in dual antiplatelet therapy, should be considered when deciding whether to implant a drug-eluting stent (DES) or bare metal stent (BMS) in an SVG. DES should be used for SVG PCI because they seem to reduce target vessel revascularization. This article reviews the evolution and contemporary evidence regarding use of DES versus BMS in SVG PCI.

NUMERICAL INVESTIGATION OF PULSATILE FLOW IN AN S-TYPE BYPASS GRAFT

Intimal hyperplasia developed at the end-to-side anastomosis of artery bypass is closely related to unphysiological hemodynamics. The helical flow as a normal physiological phenomenon in arteries is beneficial to endothelial damage repair. To deeply understand the physiological flow properties in a S-type bypass (StB) graft, four end-to-side bypass models including 30°, 45°, 60° conventional bypasses and a 45° StB were compared numerically under physiological pulsatile flow. The results showed that strong helical flow was observed at the distal anastomosis of StB. The distribution of hemodynamic parameters such as helicity, average wall shear stress and oscillating shear index, etc. were significantly improved at the S-type anastomosis as compared with those of three conventional models. The area-averaged normalized helicity in StB reached maxima at the moments of maximum flow rate and systolic deceleration. The hemodynamic performance in a 45° StB was improved as compared with a 30° conventional model. It is concluded that large StB anastomosis angle can be taken to achieve good hemodynamic performance while much smaller anastomosis angle has to be adopted for conventional bypass. As such, a S-type anastomosis should be a feasible choice of clinical artery bypass grafting due to its significant improvement in hemodynamic performance.

Perioperative outcomes in reoperative cardiac surgery guided by cardiac multidetector computed tomographic angiography

BACKGROUND

Preoperative evaluation with contrast-enhanced multidetector computed tomographic angiography (MDCTA) is considered an "appropriate" indication based on expert consensus. We aimed to evaluate how the presurgical evaluation with MDCTA impacts the outcomes after reoperative cardiac surgery (RCS).

METHODS

We retrospectively studied 364 patients undergoing RCS between 2004 and 2008, including 137 referred for MDCTA. High-risk CT findings were defined as the presence of right ventricle or aorta <10 mm from the sternum or a bypass graft <10 mm from the sternum crossing the midline. The primary clinical end point was the composite of perioperative death, myocardial infarction (MI), stoke, and hemorrhage-related reoperation. Secondary end points included surgical procedural variables and the perioperative volume of bleeding and of red blood cell (RBC) transfusion.

RESULTS

Baseline clinical characteristics were similar between the 2 groups. Individuals referred for MDCTA showed a trend toward a lower incidence of the composite primary end point (17.5% vs 24.2%, P = .13), primarily related to a significantly lower incidence of perioperative MI (0% vs 5.7%, P = .002). Multidetector computed tomographic angiography was also associated with shorter perfusion (90 vs 110 minutes, P = .002), cross clamp time (63 vs 75 minutes, P = .003), and total time in intensive care unit (103 vs 148 hours, P = .04), and a lower volume of postoperative RBC transfusion (627 vs 824 mL, P = .09). These differences remained significant after adjustment for the Society of Thoracic Surgeons score and the performing surgeon.

CONCLUSION

The use of MDCTA before RCS was associated with shorter perfusion and cross clamp time, shorter intensive care unit stays, and less frequent perioperative MI.

Dynamic straining combined with fibrin gel cell seeding improves strength of tissue-engineered small-diameter vascular grafts

Vascular tissue engineering represents a promising approach for the development of living small-diameter vascular grafts that can be used for replacement therapy. The culture of strong human tissue-engineered (TE) vascular grafts has required long culture times, up to several months, whether or not combined with gene therapy. This article describes the culture of strong, genetically unmodified, human TE vascular grafts in 4 weeks Small-diameter vascular grafts were engineered using a fast-degrading polyglycolic acid scaffold coated with poly-4-hydroxybutyrate combined with fibrin gel and seeded with myofibroblasts isolated from discarded saphenous veins from patients undergoing coronary bypass surgery. The TE grafts were subjected to dynamic strain conditions. After 28 d of in vitro culture, the grafts demonstrated burst pressures of 903 +/- 123 mmHg. Comparison with native vessels (intact human left internal mammary arteries (LIMAs) and saphenous veins) showed no significant differences in the amount of DNA, whereas the TE vessels contained approximately 50% of the native collagen content. In the physiological pressure range, up to 300 mmHg, the mechanical properties of the TE vessels were comparable to the LIMA. In this study, we showed that dynamic conditioning combined with fibrin gel cell seeding enhances the mechanical properties of small-diameter TE grafts. These grafts might provide a promising alternative to currently used vascular replacements.

Positive family history of coronary atherosclerosis and serum triglycerides may predict repeated coronary artery bypass surgery

OBJECTIVE

Cardiovascular risk factor profile of patients in need of repeated coronary artery bypass surgery (redo CABG) seldom differ from patients having only single coronary artery bypass surgery (CABG). The aim of this study was to analyse the influence of positive family history for coronary artery disease in respect to redo CABG vs CABG in a case-control setting.

DESIGN

One hundred and eighty four patients undergoing redo CABG between 1990-1998 were identified from the computed registry of the Department of Cardiothoracic Surgery in Tampere University Hospital. One hundred and eighty four age, gender and operation date matched patients with CABG were selected for control.

RESULTS

According to chi-square analysis, positive family history for coronary artery disease was more common in Study group, 60.4% versus 49.5% (p<0.05). Preoperative systolic blood pressure was 135.5+/-1.4 mmHg versus 133.5+/-1.5 mmHg (ns), preoperative diastolic blood pressure was 81.2+/-0.8 mmHg versus 82.8+/-0.9 mmHg (ns), serum total cholesterol was 5.8+/-0.1 mmol/L versus 6.6+/-1.2 mmol/L and preoperative blood glucose was 5.6+/-0.2 mmol/L versus 5.3+/-0.2 mmol/L (ns) in Controls and Study group, respectively. However, serum triglyceride level was significantly higher in Study group 2.8+/-0.2 mmol/L versus 2.0+/-0.1 mmol/L (p<0.000). In regression analysis, only positive family history (OR=2.4; 95% CI=1.1-5.1; p<0,02) and high serum triglyceride level (>or=2 mmol/L, OR=1.6; 95% CI=1.2-2.2; p<0,02) were independent predictors for redo CABG.

CONCLUSION

According to this study, positive family history for coronary atherosclerosis at the presence of high serum triglyceride level is significantly predicting the need for future redo CABG as compared with age, gender and operation time matched controls of CABG.

Stress cardiac single-photon emission computed tomographic imaging late after coronary artery bypass surgery for risk stratification and estimation of time to cardiac events

OBJECTIVE

We assessed predictors and temporal characteristics of cardiac risk in patients undergoing stress single-photon emission computed tomography after coronary artery bypass grafting.

METHODS

Stress cardiac tomography was performed in 362 patients 5 years after coronary artery bypass grafting. Cardiac death and myocardial infarction were considered as events. Cox proportional hazards analysis was used to identify predictors of events and parametric survival analysis to predict time to events.

RESULTS

During a median follow-up of 27 months, 22 cardiac events occurred (6.1% cumulative event rate). At multivariable Cox analysis, ischemia at cardiac tomography (hazards ratio 3.7, 95% confidence interval 1.5-9.1; P = .004), and diabetes (hazards ratio 3.6, 95% confidence interval 1.5-8.5; P = .006) resulted in independent predictors of events. Event-free survival was 96% in patients with normal cardiac tomography, 86% in those with abnormal tomography without ischemia, and 70% in those with (log-rank 10.6, P for trend = .008). The parametric survival model revealed that the cardiac risk was greater for all time intervals and accelerated more over time in patients with ischemia than in those without (chi(2) 21.4, P < .0001). Patients without diabetes and normal cardiac tomography remained below a defined risk level (5%) for the entire follow-up period.

CONCLUSION

Stress cardiac tomography performed 5 years after coronary artery bypass grafting is useful to characterize the risk of cardiac events and its temporal variation. Parametric survival model estimates the predicted time to risk and the level of risk at specific time intervals after coronary artery bypass grafting.

Patients having repeat coronary artery bypass graft surgery

Coronary artery bypass graft (CABG) reoperation carries an increased risk for mortality and other complications when compared with the risks and complications associated with the initial operative procedure. The purpose of this article is to describe the incidence of repeat CABG surgical procedures, risk factors, associated outcomes, and important considerations for nursing practice.

Efficacy of Physiologic Temperature on the Spasm of Harvested Radial Artery

BACKGROUND

The potential disadvantage of using the radial artery for coronary artery bypass grafting is its increased tendency to vasospasm. Therefore, different antispastic agents are being used in the perioperative and postoperative period. During the preparation of the radial artery, normal local and systemic temperatures are lost.

METHODS

We investigated the effects of topical normal saline solution at 20 degrees C (group SI), normal saline solution at 36 degrees C (group SII), diltiazem at 20 degrees C (group DI), and diltiazem at 36 degrees C (group DII) on radial artery free flow. Each group contained 10 patients undergoing coronary bypass surgery. Free flow and local temperature were measured at 3 stages: after the exploration and preparation of the distal 3 cm of the radial artery, after total preparation of the radial artery, and a median of 12 minutes after the pedicle had been sprayed with one of the agents.

RESULTS

Parallel to the significant decrease of the second local temperatures (P < .001), the second flow of the 4 groups decreased significantly (P < .001).

CONCLUSION

Hypothermia plays an important role in radial artery vasospasm, and normothermia may be the best perioperative vasodilating agent since the normal radial artery flows were reached with normothermia.

Outcome after redo coronary artery bypass grafting in patients with ischaemic cardiomyopathy and viable myocardium

BACKGROUND

Repeat coronary artery bypass grafting (redo-CABG) in patients with ischaemic cardiomyopathy is associated with high perioperative risk and worse long-term outcome compared with patients undergoing their first CABG.

OBJECTIVE

To assess whether patients with viable myocardium undergoing redo-CABG have a better outcome.

METHODS

18 patients with ischaemic cardiomyopathy underwent redo-CABG and 34 underwent their first CABG; all had substantial viability (> or =25% of the left ventricle) on dobutamine stress echocardiography (DSE). Left ventricular ejection fraction (LVEF) and heart failure symptoms were assessed before and 9-12 months after revascularisation. Cardiac event rate was assessed during the follow-up period (median 4 years, 25-75th centile 2.8-4.9 years).

RESULTS

The extent of viable myocardium on DSE was comparable in the two groups (11.3 (3.9) segments in patients who underwent redo-CABG v 12.8 (3.0) in patients who underwent their first CABG; p = NS). LVEF improved from 32% (9%) to 39% (12%); p = 0.01, in patients who underwent redo-CABG and from 30% (7%) to 36% (7%); p<0.01, in those who underwent their first CABG; New York Heart Association class improved from 2.5 (1.1) to 1.9 (0.8); p = 0.03, and from 2.7 (1.0) to 1.8 (0.70); p<0.01, respectively. In patients who underwent redo-CABG, the perioperative mortality was 0, post-surgery inotropic support was needed in 11% of the patients and mid-term (4-year) survival was 100%, with a total event rate of 28%. All these variables were not statistically different from patients who underwent their first CABG (p = 0.50, 0.90, 0.08 and 0.81, respectively).

CONCLUSION

Patients with ischaemic cardiomyopathy and substantial viability undergoing redo-CABG benefit from revascularisation in terms of improvement in LVEF, heart failure symptoms, angina and mid-term prognosis.

Is Reoperation Still a Risk Factor in Coronary Artery Bypass Surgery?

BACKGROUND

Hospital mortality for reoperative coronary artery bypass grafting (CABG) is approaching that of primary CABG. This raises two questions: (1) has experience neutralized the risk of reoperation attributable to its greater difficulty, or (2) has experience neutralized the risk attributable to the higher-risk profile of reoperative patients?.

METHODS

From 1990 to 2003, 21,568 CABG procedures were performed, of which 4,518 (21%) were reoperations: 3,919 first, 552 second, 43 third, 3 fourth, and 1 fifth. Reoperative patients had a higher-risk profile than primary patients, with more vascular disease, left ventricular dysfunction, and coronary artery disease (all p < 0.0001). Logistic regression was used to identify factors associated with hospital death and to develop a propensity score for reoperation, which was used to (1) adjust multivariable analyses of death and (2) compare outcomes in matched patients.

RESULTS

Hospital mortality was 4.3% (168 of 3,919) for first reoperation, 5.1% (28 of 552) for second, and 6.4% (3 of 47) for third or more, compared with 1.5% (263 of 17,050) for primary operations. Risk of both primary and reoperative CABG decreased with experience (p > 0.0002); however, reoperative risk fell markedly in the mid-1990s. In both the overall and matched-pairs analyses, reoperation was a risk factor before 1997 (p < or = 0.008), but not after (p = 0.2). Reoperation within 1 year of previous CABG increased risk (p < 0.0001). Risk attributable to left ventricular dysfunction decreased with experience (p = 0.05).

CONCLUSIONS

Hospital mortality for reoperative CABG has been consistently higher than for primary operation, but this difference has narrowed considerably. Patient characteristics, not reoperation itself, now have greater influence.

Reoperative Coronary Artery Bypass Grafting: Analysis of Early and Late Outcomes

BACKGROUND

The purpose of this study was to evaluate early and late results of reoperative coronary artery bypass grafting compared with those of first coronary artery bypass grafting.

METHODS

From November 21, 1994, to December 31, 2001, 4,381 patients underwent isolated coronary revascularization: among these patients, 274 (6.3%) underwent a redo. Applying the propensity score, 239 redo patients (group R) were matched with 239 who underwent the first revascularization (group F).

RESULTS

Early mortality was 2.1% (group F) and 4.2% (group R), not significantly different. Group R showed significantly higher creatine kinase myocardial band release, length of intensive care unit stay, and incidence of incomplete myocardial revascularization than group F. In group R, off-pump patients showed higher incidence of incomplete revascularization. Redo was a risk factor for abnormal (>19 IU/L) creatine kinase myocardial band release (odds ratio, 1.7; p = 0.0066) and incomplete myocardial revascularization (odds ratio, 2.4; p = 0.0060). Five-year clinical outcome was significantly worse in group R, except for freedom from redo or percutaneous transluminal coronary angioplasty. Redo was an independent variable for lower freedom from death of any cause, cardiac death, acute myocardial infarction, cardiac events, and any event. Patients with higher creatine kinase myocardial band release or incomplete myocardial revascularization showed lower freedom from cardiac-related events. Incidence of incomplete myocardial revascularization and creatine kinase myocardial band release were significantly higher in group R by both univariate and multivariate analysis. This could explain the worse late outcome of redo patients.

CONCLUSIONS

Complete revascularization without damaging the heart, whichever technique is used, is the target of redo surgery, to achieve the same quality of results obtained in the first operation.

Long-term cardiac survival after reoperative coronary artery bypass grafting

OBJECTIVE

Despite advances in cardiac surgery, the risk of reoperative coronary artery bypass surgery (RECABG) still exceeds those of a primary myocardial revascularization and also the late results are not so favourable. In this study, long-term cardiac survival is analyzed.

METHODS

We analyzed long-term cardiac survival of 466 patients who survived the first 6 months after a RECABG between January 1987 and December 1998. Actuarial survival estimates were calculated and pre- and peroperative variables were analyzed to identify predictors of long-term cardiac related mortality.

RESULTS

Mean follow-up was 7.7 +/- 3.8 years (1-17 years), and follow-up was 95.6% complete. One-year cardiac survival was 98.2%, 5-year: 91.0%, 10-year: 78.7% and 14-year survival 60.2%. Cardiac survival was only significantly superior for patients under 65 years of age at the moment of the RECABG. Impaired left ventricular function was identified as the only independent predictor of late cardiac-related mortality.

CONCLUSION

The long-term survival in patients undergoing RECABG is acceptable. Once patients survived the first 6 postoperative months, advanced age (>65 years) is affecting long-term cardiac survival and impaired left ventricular function is the only independent predictor of late cardiac mortality.

Effects of anastomotic angle on vascular tissue responses at end-to-side arterial grafts

OBJECTIVE

Hemodynamics has been implicated in the late failure of arterial bypass grafts, which frequently occurs at the distal anastomosis site. This study was designed to assess the relationship between local hemodynamics and pathologic responses of the distal anastomosis by manipulation of the angle of anastomosis of the graft, a major determinant of local hemodynamics.

METHODS

End-to-side anastomoses of the right carotid to the left carotid arteries of rabbits were performed at anastomotic angles of less than 10 degrees (acute), 45 degrees (intermediate), or 90 degrees (right angle), and then the upstream left carotid arteries were ligated to simulate pathologic occlusion. We examined tissue responses on the wall of the recipient vessel opposite the anastomosis site (the bed), where unusual hemodynamic forces are imposed.

RESULTS

Three months after surgery, intimal thickening was observed on the upstream portion of the acute, and more rarely, the intermediate anastomoses only. Medial thinning caused by loss of cells and matrix, and an aneurysm-like dilation, was observed in the right angle and some intermediate anastomoses, but not in the acute anastomoses. En face confocal microscopy at 3 weeks after surgery revealed severe disruption of the internal elastic lamina in all anastomotic models. Zymography and Western immunoblotting demonstrated gelatinolytic activity, caused by expression and activation of MMP-2, that was lowest in the acute anastomoses, higher in the intermediate anastomoses, and highest in the right-angle anastomoses.

CONCLUSIONS

We infer that very different pathologic changes to the vessel wall are elicited when local hemodynamics is manipulated by altering the anastomotic branch angle.