Vein Coronary Artery Bypass Grafts Research Articles

Antithrombotic therapy in patients receiving saphenous vein coronary artery bypass grafts: a protocol for a systematic review and network meta-analysis

IntroductionThe current evidence for the prevention of saphenous vein graft failure (SVGF) after coronary artery bypass graft (CABG) surgery consists of direct head-to-head comparison of treatments (including placebo) in randomised-controlled...

Long-term results of sequential vein coronary artery bypass grafting compared with totally arterial myocardial revascularization: a propensity score-matched follow-up study

The aim of the study was to analyse the early and long-term outcomes of a consecutive series of patients who underwent sequential coronary artery bypass grafting (CABG) and to compare them with a matched population of totally arterial revascularized patients. From January 1994 to December 1996, 209 patients underwent total arterial myocardial revascularization at our institution [arterial (ART) group]. In the same period, 2097 patients underwent CABG with left internal thoracic artery on left anterior descending and great saphenous vein on the right and circumflex branches sequentially [sequential vein (SV) group]. The propensity score methodology was used to obtain risk-adjusted outcome comparisons between the two groups (209 vs 243 patients in the ART group and SV group, respectively). In-hospital mortality was 1% in the ART group and 0.4% in the SV group (P = 0.86). Mean follow-up was 14 ± 4 years. Long-term survival was comparable among the two study groups [actuarial 5- and 15-year survival rates were 97 vs 93% and 82 vs 79% in the ART group and the SV group, respectively (P = 0.29)]. At follow-up, recurrence of angina (17 vs 18%; P = 0.99), acute myocardial infarction (MI) (3 vs 5%; P = 0.72) and repeated percutaneous coronary intervention (19 vs 21%; P = 0.69) were similar in the ART group compared with the SV group. In the Cox regression analysis, type of revascularization was not an independent predictor of any long-term outcomes (death or major adverse cardiac events). In asymptomatic patients, exercise stress test at follow-up was comparable between the two groups (P = 0.14). Sequential vein CABG appears to have good early and long-term clinical outcomes. Also, early and long-term incidence of acute MI was not significantly higher in the SV group. However, further studies with a larger population are warranted in order to confirm the present results.

Morphological and functional 3-Tesla magnetic resonance imaging of saphenous vein coronary artery bypass grafts

Evaluation of a novel non-invasive tool for postoperative follow-up of patients postelective saphenous vein coronary artery bypass graft (CABG) was performed. Ten patients were included. Their bypass grafts supplied the right coronary artery (7), marginal branches (1), diagonal branches (2), and the circumflex artery (n=1). Each bypass was examined intraoperatively using Doppler flow measurement. Patients were examined with a 3-Tesla magnetic resonance imaging (MRI) scanner (MAGNETOM Verio, Siemens, Erlangen, Germany) within one week postsurgery using MR-angiography with an intravasal contrast agent and velocity encoded phase-contrast flow measurements. Intraoperative Doppler flow measurements revealed regular flow patterns in all vascular territories supplied. The median intraoperative flow rate was 50 ml/min with an inter-quartile range (IQR) of 42-70 ml/min. The clinical postoperative course was uneventful. MRI showed all grafts to be patent. The median postoperative flow rate was 50 ml/min (IQR: 32-65 ml/min). MRI flow rates agreed well with intraoperative Doppler flow measurements (mean difference: -2.8±20.1 ml/min). This initial study demonstrates that 3-Tesla MRI flow measurements correlated well with Doppler thus reconfirming the graft patency postCABG. Further refinement and broader application of this technique may facilitate follow-up postCABG potentially replacing empiric clinical judgment by reliable non-invasive imaging.

Coronary Artery Bypass Graft for Anomalous Right Coronary Artery

A 27-year-old man with anomalous right coronary artery (RCA) presented with ventricular fibrillatory arrest. Computed tomography angiography revealed an anomalous RCA arising from the left sinus of Valsalva with an acute angulation at the coronary takeoff and compressed interarterial segment. This patient underwent a short saphenous vein coronary artery bypass graft to the proximal RCA and recovered uneventfully. A review of the literature and discussion of the surgical management is presented.

Thermal coronary angiography for intraoperative patency control of arterial and saphenous vein coronary artery bypass grafts: results in 370 patients.

Early graft failure is often associated with technical failures and is therefore potentially avoidable. We used thermal coronary angiography (TCA) for intraoperative graft patency control in 370 patients undergoing routine coronary artery bypass graft surgery to determine whether consequent intraoperative bypass graft control may result in improved patency rates. The temperature differences generated in between the myocardium and the grafts by injecting cold cardioplegic solution into the proximal end of a vein graft or by warmer blood running through an internal thoracic artery (ITA) graft were detected using three different infrared camera systems. The resulting "heat pictures" were evaluated for anastomotic patency and to outline graft anatomy. A total of 693 vein grafts were visualized. In 9.4% TCA failed to produce usable images. In the remaining 628 grafts, TCA revealed intraoperative patency in 98.8%. Out of 370 ITA grafts, only 14 could not be sufficiently visualized by TCA. Nineteen ITA occlusions (5.3%) were found: 5 intimal flaps; 11 suture imposed strictures; and 3 proximal ITA occlusions. All occluded grafts were subsequently revised or replaced. All sequential ITA as well as 15 right ITA grafts proved to have patent anastomoses. Using TCA an early graft dysfunction rate of 1% for vein grafts and 5.3% for ITA grafts could be demonstrated. Most occlusions were due to technical mistakes at the distal anastomosis. TCA outlines grafts and the attached coronaries by temperature differences without the need for a contrast agent. There is no interference with the surgical procedure. It is an ideal, noninvasive method to immediately document the success or failure of myocardial revascularization.

Biomechanical stress induces novel arterial intima-enriched genes: implications for vascular adaptation to stress

The arterial vasculature is subjected to considerably greater biomechanical stress than the venous circulation. This is reflected in the difference in morphology between large arteries and veins, however little is known about the molecular differences that arise as a consequence of biomechanical stress. Previously, we identified a group of arterial intima-enriched (AIE) genes: sciellin, periplakin, SPRR3, envoplakin, galectin 7, and plakoglobin that are functionally related in that they contribute to the stress properties of stratified epithelium. We sought to test our hypothesis that these genes were regulated by biomechanical stress in vascular smooth muscle cells (VSMCs). Immunofluorescence was employed to determine the expression of the AIE genes in saphenous vein coronary artery bypass grafts. Furthermore, we used a model of cyclic stress to determine if the AIE genes were regulated by biomechanical stress in VSMCs in vitro. Sciellin and periplakin were upregulated in saphenous vein coronary artery bypass grafts after arterialization, but were absent in non-arterialized saphenous veins. Sciellin, SPRR3, and periplakin transcripts were all upregulated (4.67-, 4.95-, 2.77-fold, respectively) by prolonged exposure to cyclic strain (24-72 h), but not at earlier time points. These findings suggest a novel role for several human AIE genes in the VSMC response to arterialization and extended cyclic strain. Biomechanical stress has long been implicated in vascular pathologies. We report the novel finding of a group of genes, previously studied in stratified epithelium, that were regulated by prolonged cyclic stress in vascular smooth muscle cells. This may have important implications to vascular disease.

Constitutive Equations for Human Saphenous Vein Coronary Artery Bypass Graft

Constitutive Equations for Human Saphenous Vein Coronary Artery Bypass Graft

Embolic Protection in Infrainguinal Interventions

The benefits of the use of embolic protection devices (EPDs) in saphenous vein coronary artery bypass grafts and carotid arteries have been shown, but the utility of their application during infrainguinal endovascular interventions is somewhat unclear. Patients with specific anatomical features or lesion characteristics, or patients undergoing specific types of endovascular interventions may benefit from the off-label use of EPDs, but this has yet to be determined. This report will examine the current literature related to the use of EPDs in infrainguinal endovascular interventions and attempt to identify the patients who would most likely benefit from their use. In addition, the setting in which EPDs have been used at one institution is briefly described. This discussion will serve as a general guideline for the use of EPDs and act as an impetus for the development of future clinical trials to help elucidate the patients who will truly benefit from EPDs use when undergoing lower extremity endovascular revascularization procedures.

Hemodynamic evaluation of saphenous vein coronary artery bypass grafts: Relative merits of Doppler flow velocity and SPECT perfusion imaging

Coronary angiography is considered the gold standard in evaluating vein graft disease; however, angiography does not allow assessment of hemodynamic consequences of lesions. In this study hemodynamic consequences of significant stenoses in vein grafts were evaluated by Doppler velocity assessment, and results were compared with single photon emission computed tomography (SPECT) perfusion imaging. Angiography was performed in 58 patients after coronary artery bypass grafting because of recurrent chest pain. During the procedure, Doppler velocity measurements were acquired before and after administration of adenosine. Of 58 patients (with 78 vein grafts), 20 patients (with 24 vein grafts) underwent SPECT perfusion imaging. Grafts were divided into those with nonsignificant percent diameter stenosis (< 50%) (n = 49) and those with significant percent diameter stenosis (> or =50%) (n = 29). When a cutoff value for coronary flow velocity reserve (CFVR) of 1.8 was applied, modest agreement (69%, kappa = 0.25, P < .05) between CFVR and angiography was shown. Agreement between SPECT and angiography was also modest (63%, kappa = 0.28, P = not significant). SPECT and CFVR provided comparable information in 20 of 24 grafts with available SPECT, illustrating good agreement (83%, kappa = 0.61, P = .001). Significant stenoses in vein grafts require further exploration to assess their hemodynamic significance. The Doppler velocity results agreed better with SPECT perfusion imaging than with percent diameter stenosis in the evaluation of vein graft function.

Rupture of a Saphenous Vein Coronary Artery Bypass Graft Due to Aspergillus Necrotizing Vasculitis

We present the first, unusual case of a lethal mediastinal hemorrhage caused by rupture of a saphenous vein aortic coronary bypass graft due to Aspergillus species necrotizing vasculitis in an immunocompetent patient 18 days after redo coronary artery bypass surgery. The patient had neither signs for mediastinitis nor for another source of Aspergillus infection.

Evaluation of Saphenous Vein Coronary Artery Bypass Graft Flow by Cardiovascular Magnetic Resonance

Cardiovascular magnetic resonance (CMR) with flow velocity mapping has emerged as a noninvasive method to measure flow in saphenous vein coronary artery bypass grafts. The aim of the current study was to retrospectively test two previously described analysis methods on a large CMR data set and to compare their diagnostic accuracy in detecting diseased vein grafts. In 125 vein grafts of 68 patients, volume flow parameters (volume flow, systolic and diastolic peak flow, diastolic-to-systolic flow ratio at rest and during adenosine stress, and flow reserve) were derived from the velocity maps. Method 1 implemented basal flow < 20 ml/min or flow reserve < 2, yielding a sensitivity and specificity of 70% and 38% in the detection of a diseased graft or recipient vessel. Method 2 used receiver operating characteristic (ROC) curve analysis and implemented all significant volume flow parameters in a logistic regression model, yielding a sensitivity of 74% with a specificity of 68% in the detection of a diseased graft or recipient vessel. Evaluating single and sequential grafts separately, this method yielded a sensitivity and specificity of 79% and 87% for single grafts, and 62% and 94% for sequential grafts in the detection of > or = 50% stenosis in grafts or recipient vessels. Cut-off values were formulated for the respective volume flow parameters, which maximally separate grafts with and without > or = 50% stenosis. Using ROC curve analysis with logistic regression the specificity of the analysis method improved considerably. For the current data set the best results were acquired when single and sequential grafts were separately analyzed.

Evaluation of Saphenous Vein Coronary Artery Bypass Graft Flow by Cardiovascular Magnetic Resonance

Evaluation of Saphenous Vein Coronary Artery Bypass Graft Flow by Cardiovascular Magnetic Resonance

Coronary Artery Surgery

Coronary Artery Surgery

Pressure-Induced Vector Transport in Human Saphenous Vein

The efficiency of gene therapy as a pretreatment for saphenous vein coronary artery bypass grafts can be improved by increasing the transport of vector into the tunica media. The purpose of this study was to determine the effect of increasing transmural pressure on vector delivery depth in human saphenous vein segments. Specifically, we introduced adenovirus-sized microspheres luminally to observe changes in transport efficiency into the intimal and medial layers with increasing pressure. Our results indicate that transmural pressures of 100 and 400 mmHg increase the intimal concentration of microspheres as compared to 0 mmHg (p < 0.03), but do not significantly affect medial concentrations. We did not find increasing concentrations with increasing pressure above 100 mmHg. These results suggest that low or intermediate transmural pressures are adequate for intimal vector delivery and that techniques other than increasing pressure are required to deliver gene therapy vectors (> or = 100 nm) to medial smooth muscle cells. Also, our data support previous models designating the internal elastic lamina as the primary barrier to particle transport. Finally, our ex vivo microsphere perfusion experiment represents a novel way to explore functional vein permeabilities to gene therapy vectors and, ultimately, optimize vascular gene therapy protocols.

Human Saphenous Vein Coronary Artery Bypass Graft Morphology, Geometry and Hemodynamics

Coronary artery bypass graft (CABG) failure has been linked to graft hemodynamics, in particular wall shear stress. This study characterizes the morphology, geometry and wall shear stress patterns in human CABGs. The intimal thickness (IT) in 49 human saphenous vein CABGs was measured by digital light microscopy. The geometry of six saphenous vein CABGs was replicated by post-mortem infusion of Batson's #17 anatomical corrosion casting compound. Graft hemodynamics were evaluated in two flow models, fabricated from the casts, under steady (Re = 110) and pulsatile flow (Re = 110, alpha = 2) conditions. Saphenous vein CABGs in situ for more than 2 months had, on average, the greatest IT on the hood and suture sites of the distal anastomosis. Floor thickening was highly variable and significantly less than IT at the hood, suture site and graft body. All casts showed an indentation along the floor and 5/6 casts displayed a sharp local curvature on the hood. In both flow models, a large increase in wall shear rate occurred on the hood, just proximal to the toe. The local geometry of the hood created this large spatial gradient in wall shear stress which is a likely factor in hood intimal hyperplasia.

Native Matrix Metalloproteinase Characteristics May Influence Early Stenosis of Venous Versus Arterial Coronary Artery Bypass Grafting Conduits

Stenosis and occlusion rates of internal mammary artery (IMA) and saphenous vein (SV) coronary artery bypass grafts (CABGs) are markedly different, which result from respective disparities in vascular remodeling. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) regulate vascular structure and may have important influence on graft patency. However, the MMP milieu and expression profile of the IMA and SV have not been contrasted. Therefore, the aim of this study was to assess and compare the native MMP systems in IMA vs SV conduits. IMA (n = 10) and SV (n = 10) specimens were obtained from patients undergoing CABG surgery. Protein levels of MMP-1, MMP-2, and MMP-9, TIMP-1, a membrane-bound MMP activator (MT1-MMP), and an extracellular MMP inducer protein (EMMPRIN) were determined by immunoblotting and quantified by densitometric analysis. MMP-2 and MMP-9 activity was determined by gelatin zymography. MMP-2 levels were significantly higher in SV (2,218 +/- 351 pixels) vs IMA (1,012 +/- 213 pixels) specimens (mean +/- SEM]). There were no significant differences in MMP-1, MMP-9, or TIMP-1 content; however, MT1-MMP and EMMPRIN levels were significantly lower in SV (847 +/- 190 pixels, 1,742 +/- 461 pixels) vs IMA conduits (2,590 + 403 pixels, 5,606 + 678 pixels), respectively (p < 0.05). MMP-9 activity was similar while MMP-2 activity was significantly increased in SV vs IMA specimens. SV and IMA conduits harbor the same MMP molecular constituents. However, MMP-2 levels and activity are significantly more abundant in the SV compared to the IMA. These differences may contribute to the early pathologic remodeling of the SV vs IMA conduit following CABG surgery.

Development of a saphenous vein coronary artery bypass graft pseudoaneurysm

This report shows the long-term development of a saphenous vein bypass pseudoaneurysm that is a rare complication after bypass surgery. The patient underwent CABG procedure in 1986 because of three vessel coronary artery disease. Initial signs of venous wall disturbances were observed first time in 1996. At the present admission the patient complained of angina pectoris probably resulting from progression of coronary artery disease. Angiography revealed an approximately 15x8 mm enlarged venous graft pseudoaneurysm. Subsequently, the entrance was successfully occluded by a covered stent graft. Six month follow-up was uneventful; angiography showed a still sufficiently occluded pseudoaneurysm.

1157-46 Hemodynamic impairment of intermediate stenoses in saphenous vein coronary artery bypass grafts and recipient vessels: Evaluation by doppler flow velocity

1157-46 Hemodynamic impairment of intermediate stenoses in saphenous vein coronary artery bypass grafts and recipient vessels: Evaluation by doppler flow velocity

The hemodynamic effects of compliance, bulging, and curvature in a saphenous vein coronary artery bypass graft model

The development of Intimal Hyperplasia (IH) in saphenons vein coronary artery bypass grafts (SV-CABG) is responsible for the short-term patency of these grafts. Previous studies of SV-CABG models w...

The hemodynamic effects of compliance, bulging, and curvature in a saphenous vein coronary artery bypass graft model

The development of Intimal Hyperplasia (IH) in saphenous vein coronary artery bypass grafts (SV-CABG) is responsible for the short-term patency of these grafts. Previous studies of SV-CABG models were performed on rigid anastomotic vessels. However, the effects of compliance, bulging and curvature at the anastomosis on the general hemodynamic field, due to compliance and geometric mismatch between the vein and the artery have not been evaluated. We studied axial and transverse velocities by Laser Doppler Velocimetry on a compliant, in vitro, anatomical model of an end-to-side saphenous vein graft (SVG) to left anterior descending (LAD). The model incorporated a bulge at the sinus and curvature at the graft-host junction. Physiologic pressure and flow conditions pertaining to SV-CABG were applied. The presence of the bulge and curvature showed differences in the velocity profiles in comparison with previous rigid model studies. Dynamic separation zones were temporally augmented at the flow divider. The moving stagnation point at the floor of the host vessel was observed to move past the toe of the model during the accelerating portion of the cycle. These findings suggest that the presence of the bulge curvature and compliance may further favor conditions for the development of intimal hyperplasia (IH) at the floor of a CABG.