Virchow Triad, but Not Use of an Aortic Connector Device, Predicts Early Graft Failure after Off-Pump Coronary Bypass

In-Hospital Graft Occlusion in Post-Coronary Artery Bypass Grafting Patients in the Early Postoperative Period: A Systematic Review and Meta-Analysis

Objectives: The objectives of this paper are to evaluate the incidence of early graft occlusion during hospital stays following coronary bypass surgery (CABG) and to assess the factors influencing the odds of in-hospital early graft occlusion. Methods: Reports evaluating the early in-hospital occlusion of coronary bypass grafts were identified through PubMed, Embase, and Cochrane databases. The primary endpoint was to determine the incidence of early graft occlusion following CABG before discharge and to identify and quantify the impact of demographic, clinical, and procedural risk factors on the occurrence of early graft occlusion. The meta-analysis was conducted using a random-effects inverse-variance model with the DerSimonian-Laird estimator, assessing incidence rates, risk factors, and study heterogeneity, with statistical analysis performed using Stata. Results: A total of 22 studies with 35,798 patients were included in the analysis. The overall incidence of in-hospital early graft occlusion was 5% (95% CI: 3% to 7%). In studies using symptom-driven patency assessment, the incidence of occlusion was 2%, whereas in those employing systematic graft patency assessment, it was 6%. Only the presence of a vein graft OR 2.13 (95% CI: 1.19-3.82) was significantly associated with in-hospital graft occlusion. Conclusions: The incidence of in-hospital early graft occlusion seems substantially underestimated if imaging is restricted only to symptomatic patients. Moreover, female gender, increased PI, and the presence of a composite graft could also be potential risk factors for this complication.

Antegrade cardioplegia as a possible cause of acute saphenous vein endothelial damage in patients undergoing on pump coronary artery bypass surgery

Background

The administration of antegrade cardioplegia through vein grafts after the completion of each distal anastomosis is a common practice. However, the cardioplegic solution may disrupt the vein endothelium and contribute to late vein graft atherosclerotic disease. This study aimed at evaluating the possible impact of the cardioplegic solution on vein graft endothelium.

Methods

Total of 52 patients (16 women and 36 men) aged 68±8.5 years old that underwent on pump coronary revascularization with at least one vein graft were enrolled. Sections of grafts from the greater saphenous vein were obtained prior to and after delivery of potassium antegrade cardioplegic solution through them. These sections were then examined histologically with immunochemical stain and CD34 index. The endothelial damage and length of vein specimens of both graft sections were evaluated.

Results

The endothelial damage of vein specimens appeared to be increased significantly with exposure to antegrade cardioplegia in male and female patients (P from Wilcoxon tests <0.001, for both genders). The increase in the length of vein specimens was significant too (P from Wilcoxon test <0.001 for men and P=0.001 for women).

Conclusions

Antegrade cardioplegia delivered through vein grafts causes substantial damage on vein endothelium. This may have an adverse effect on long-term graft patency.

Virchow’s triad and intestinal ischemia post cardiac surgery

Background

Intestinal ischemia is associated with a very high mortality rate. We combined the principles of Virchow’s triad to produce preoperative and postoperative models for the development of intestinal ischemia.

Methods

A single institutional study was undertaken involving 18,325 consecutive patients from April 1997 to March 2012. Univariate and multivariate analysis was performed.

Results

Mortality was 87% in 91 patients who developed bowel ischemia. Multivariate logistic regression demonstrated that age, peripheral vascular disease, intraaortic balloon pump support, female sex, and preexisting renal failure were significant determinates of intestinal ischemia preoperatively. Logistic regression demonstrated that age, peripheral vascular disease, creatine kinase-MB level, reoperation for bleeding, and blood product usage were significant determinates of intestinal ischemia postoperatively.

Conclusions

Potentially remedial causes of intestinal ischemia include blood product usage, reoperation for bleeding, and creatine kinase-MB release. Age, female sex, peripheral vascular disease, intraaortic balloon pump usage, and preexisting renal failure are fixed risk factors. Despite the continuing trend of reduced blood product usage in the field of cardiac surgery, the increase in patients’ risk factors will mean that incidences of intestinal ischemia may increase in the future.

Establishing the case for minimally invasive, robotic-assisted CABG in the treatment of multivessel coronary artery disease

The purpose of this review is to outline the most common objections about robotic coronary artery bypass graft (CABG), often expressed by cardiac surgeons, cardiologists, and administrators who have little direct knowledge of the procedure. The summarized objections include the high intraoperative costs of robotic versus traditional CABG, a prolonged and difficult learning curve for members of the surgical team, and concerns about compromising graft patency with this technique. Arguments for continued procedure development in robotically assisted CABG are provided.

Coronary artery bypass grafts and MDCT imaging: what to know and what to look for

Multi-detector row CT (MDCT) scanners with high spatial and temporal resolutions are now available and are increasingly used for non-invasive assessment of vascular disease, including coronary arteries and coronary artery bypass grafts (CABG). Follow-up of patients who have previously undergone surgical revascularization for coronary artery disease is nowadays one of the main applications of MDCT. Thanks to the continuous technical evolution of the CT scanners, it is now possible to scan the heart and the full anatomic extent of grafts with sub-millimeter slice-thickness within a single breath-hold. In the evaluation of these patients, it is important for the radiologist to be familiar with the different types of grafts and surgical techniques to know the main characteristics of each graft type and what to look for in the assessment of a patient who has undergone coronary artery surgical revascularization. This review summarizes some surgical aspects, the biological characteristics of conduits, and the main technical MDCT features, and describes the CABG anatomy together with some typical CT findings.

Disruption of graft endothelium correlates with early failure after off-pump coronary artery bypass surgery

BACKGROUND

Saphenous vein graft failure after coronary artery bypass surgery may be as high as 5% to 10% in the first postoperative week. We hypothesized that identifying damage sustained by saphenous vein endothelium before grafting predicts early graft attrition after off-pump coronary artery bypass graft surgery.

METHODS

Intraoperative graft flow, platelet function, and endothelial integrity were analyzed in 125 patients undergoing off-pump coronary artery bypass graft surgery. Endothelial integrity was assessed in an excess vein segment from each graft using immunohistochemistry (CD31 staining). Platelet function was monitored just before and immediately after revascularization and on postoperative days 1 and 3 using whole blood aggregometry, thrombelastography, and platelet activated clotting time. Platelet activation was monitored using flow cytometry. Intraoperative conduit blood flow, measured by transit time ultrasonography, was used to detect and rectify anastomotic problems. Early graft patency was determined on postoperative day 5 using gated multichannel computed tomography angiography.

RESULTS

In 106 patients undergoing postoperative computed tomography evaluation, 10 vein grafts in 10 patients were discovered to have developed early thrombosis, representing 4% (10 of 217) of all vein grafts. Endothelial integrity was 10.75% +/- 17.56% in 10 grafts that failed early compared with 51.45% +/- 36.29% in patent grafts (p = 0.04). Perioperative platelet function and graft flow did not differ significantly between the two groups.

CONCLUSIONS

Although endothelial disruption predicts early failure of bypass grafts, the importance of a hypercoaguable state and low graft flow as a cause of early graft thrombosis after off-pump coronary artery bypass graft surgery was not supported by our preliminary results. A means to assess, prevent, and treat intraoperative vein graft damage will likely improve early graft patency.

Endothelial injury and acquired aspirin resistance as promoters of regional thrombin formation and early vein graft failure after coronary artery bypass grafting

OBJECTIVE

The predominant mechanism of early graft failure after coronary artery bypass grafting remains in doubt. Aspirin administered in the initial hours after coronary artery bypass grafting improves graft patency, implicating prostanoid synthesis in the pathogenesis. We hypothesized that synergy between endothelial disruption in the venous conduit and aspirin resistance would cause vein graft failure.

METHODS

Aspirin resistance, defined by diagnostic findings on at least two of three separate assays, was serially assessed in 225 patients undergoing off-pump coronary artery bypass grafting. Endothelial cell integrity was determined in surplus segments obtained from 408 vein grafts. The deposition of intraluminal thrombin within the vein was determined by comparing serum F1.2 levels between the coronary sinus and the aorta after grafting. Intraoperative blood flow in the grafts was measured with transit-time technology, and patency was assessed with electrocardiographically gated multichannel computed tomographic coronary angiography on day 5. Aspirin was the sole antithrombotic agent used during the study.

RESULTS

Thrombosed grafts (16/408) showed more endothelial cell loss at the time of grafting than did those grafts that remained patent (10.8% +/- 21.5% vs 51.4% +/- 39.1% integrity, P < .01). Aspirin resistance occurred in 67 patients (30%). Graft thrombosis was associated with aspirin resistance (P < .04) and reduced endothelial integrity (P < .01). These factors coexisted in 14 of 16 grafts that failed and were associated with elevated coronary sinus F1.2 levels.

CONCLUSION

Aspirin resistance and relatively compromised venous endothelial cell integrity together marked patients whose vein grafts failed within days after off-pump coronary artery bypass grafting. These observations form a basis for identifying patients at risk and developing approaches to prevent vein injury or to selectively intervene in high-risk circumstances.

Coronary Artery Bypass Grafts: Assessment with Multidetector CT in the Early and Late Postoperative Settings

Coronary artery bypass graft (CABG) surgery is the standard of care in the treatment of advanced coronary artery disease. It is well known that the long-term clinical outcome after myocardial revascularization depends on the patency of the bypass grafts. In the past, invasive coronary angiography was used to assess the status of the grafts and check for graft occlusion. Recently, computed tomography (CT), particularly multidetector CT with electrocardiographic gating, has emerged as an important diagnostic tool for evaluation of CABGs in both the early (< or =1 month) and late (>1 month) postoperative settings. A variety of postoperative complications may manifest as dyspnea and chest pain, thereby mimicking recurrent angina secondary to graft occlusion. Owing to its improved spatial resolution compared with that of earlier-generation CT scanners and its ability to produce three-dimensional and multiplanar images, multidetector CT has assumed an integral role in characterization of graft patency while allowing investigation of alternative postoperative complications. In addition, the expanded capabilities of volumetric imaging may provide valuable information in preoperative planning for repeat CABG surgery.