Vasa Vasorum in Saphenous Vein for CABG: A Review of Morphological Characteristics.

This short article discusses selected scanning electron microscope and transmission electron microscope features of vasa vasorum including pericytes and basement membrane of the human saphenous vein (SV) harvested with either conventional (CON) or no-touch (NT) technique for coronary artery bypass grafting. Scanning electron microscope data shows the general damage to vasa vasorum of CON-SV, while the transmission electron microscope data presents ultrastructural features of the vasa in more detail. Hence there are some features suggesting pericyte involvement in the contraction of vasa blood vessels, particularly in CON-SV. Other features associated with the vasa vasorum of both CON-SV and NT-SV preparations include thickened and/or multiplied layers of the basement membrane. In some cases, multiple layers of basement membrane embrace both pericyte and vasa microvessel making an impression of a "unit" made by basement membrane-pericyte-endothelium/microvessel. It can be speculated that this structural arrangement has an effect on the contractile and/or relaxing properties of the vessels involved. Endothelial colocalization of immunoreactive inducible nitric oxide synthase and endothelin-1 can be observed (with laser confocal microscope) in some of the vasa microvessels. It can be speculated that this phenomenon, particularly of the expression of inducible nitric oxide synthase, might be related to structurally changed vasa vessels, e.g., with expanded basement membrane. Fine physiological relationships between vasa vasorum endothelium, basement membrane, pericyte, and perivascular nerves have yet to be uncovered in the detail needed for better understanding of the cells'specific effects in SV preparations for coronary artery bypass grafting.

Does perivascular fibrin glue application have a preventive effect for the endothelial damage on saphenous vein graft? An experimental model.

BACKGROUND: The effect of tissue adhesives on coronary grafts in cardiac surgery is a controversial issue. OBJECTIVE: The aim of this study is to investigate the effect of fibrin glue (FG) applied around the saphenous vein grafts (SVG) in preventing cellular damage resulting from intraluminal pressure increase. METHODS: Twenty volunteer patients were included in this ex vivo study. The SVGs remained after coronary artery bypass grafting were connected to the arterial line of the cardiopulmonary bypass circuit. The grafts were divided into two segments and one segment received perivascular FG applied whereas the other part was used plain. SVGs were kept in circulation at 120 mmHg pressure 250 mL/min flow rate for 60 min. The tissues were sent for histopathological examination to determine the endothelial damage. RESULTS: Endothelial damage was more pronounced in the control group when compared with the FG group. In the FG group, no damage was seen in 13 samples and no Type 3 endothelial damage was observe whereas Type 1 injury was detected in seven specimens, Type 2 injury was observed in seven specimens, and Type 3 injury was detected in two specimens in the control group. CONCLUSION: Perivascular application of FG on the SVG showed a protective effect against endothelial damage resulting from increased intraluminal pressure.

ANTECEDENTES: El efecto de los adhesivos tisulares sobre los injertos coronarios en cirugía cardíaca es un tema controvertido. OBJETIVO: Investigar el efecto del pegamento de fibrina aplicado alrededor de los injertos de vena safena para prevenir el daño celular resultante del aumento de la presión intraluminal. MÉTODO: En este estudio ex vivo fueron incluidos 20 pacientes voluntarios. Los injertos de vena safena que quedaron después del injerto de derivación de la arteria coronaria se conectaron a la línea arterial del circuito de derivación cardiopulmonar. Los injertos se dividieron en dos segmentos y a uno de ellos se le aplicó pegamento de fibrina perivascular, mientras que la otra parte se usó sola. Los injertos de vena safena se mantuvieron en circulación a una presión de 120 mmHg y una velocidad de flujo de 250 ml/min durante 60 minutos. Los tejidos se enviaron para examen histopatológico para determinar el daño endotelial. RESULTADOS: El daño endotelial fue más pronunciado en el grupo de control que en el grupo de pegamento de fibrina. Se observó lesión de tipo 2 en siete muestras del grupo de pegamento de fibrina y lesión de tipo 3 en dos muestras del grupo de control. CONCLUSIONES: La aplicación perivascular de pegamento de fibrina en los injertos de vena safena mostró un efecto protector contra el daño endotelial resultante del aumento de la presión intraluminal.

No-Touch Saphenous Vein - Vascular Damage and the London Connection.

In this review, I summarise the circumstances leading to the collaboration between London and Örebro on the basic research performed to study potential mechanisms underlying the improved patency of saphenous veins harvested by the no-touch technique. Histological studies reveal various forms of vascular damage to saphenous vein grafts harvested in conventional coronary artery bypass grafting (CABG) whereas no-touch grafts retain a normal architecture. The perivascular fat that remains intact on no-touch saphenous vein grafts seems to play a particularly important role as the "protector" of all layers of the graft. In addition, the perivascular fat is a source of adipose cell-derived factors that may contribute to the success of the no-touch technique. While a number of trials have compared no-touch with conventional grafts following CABG, these have generally been limited to short follow-up periods, low patient numbers, and inadequate histological data. When handling no-touch saphenous vein at harvesting, there is no direct contact of the vein by surgical instruments, spasm does not occur, and high-pressure intraluminal distension is not required. While damage to both endothelial and vascular smooth muscle cells are evident at the microscopic and ultrastructural level in conventional saphenous vein grafts, their structure in no-touch grafts is preserved. Also, in no-touch veins, the vasa vasorum remains intact and transmural blood supply is maintained. This microvascular network is disrupted during conventional harvesting, a situation likely to stimulate processes involved in graft occlusion. The use of excess graft material for histology is to be encouraged for the assessment of vascular damage and even surgeon competence. If you don't look, you don't find.

Pathophysiology and Mechanisms of Saphenous Vein Graft Failure.

INTRODUCTION: Coronary artery bypass grafting remains one of the best therapies for advanced coronary artery disease. The most used conduit remains the great saphenous vein, which is susceptible to short-term and long-term failure, the result of acute thrombosis, intimal hyperplasia, and late superimposed atheroma. In this review, we present the current findings related to the pathophysiology of vein graft failure. METHODS: A search of three databases - MEDLINE®, Web of Science™, and Cochrane Library - was undertaken for the terms "pathophysiology", "prevention", and "treatment" plus the term "vein graft failure". RESULTS: The pathophysiology of saphenous graft failure can be classified in three distinct phases - acute thrombosis, intimal hyperplasia, and accelerated atherosclerosis. All these processes start with an underlying histological predisposition of the vein and at the time of harvesting and preparation for grafting. These mechanisms are a result of localized inflammatory and prothrombotic cascades that obey different causes, but ultimately result in the stenosis or occlusion of the vein graft. CONCLUSION: The interaction between the different parts of the pathophysiology of vein graft failure is extremely complex and variable. Recent improvements in surgical techniques and secondary pharmaceutical prevention like early aspirin administration and long-term statin treatment have significantly reduced early and late saphenous vein graft failure. However, this continues to be a fascinating area of research with the potential for further improvement for patients and health service provision.

Angiographic Patency of Coronary Artery Bypass Conduits: An Updated Network Meta-Analysis of Randomized Trials.

INTRODUCTION: The second best conduit for coronary artery bypass grafting is uncertain. The objective of this study is to determine the second best conduit according to graft patency results from randomized controlled trials using a network meta-analysis. METHODS: A systematic literature search was conducted for randomized controlled trials comparing the angiographic patency rate of the no-touch saphenous vein (NT-SV), the radial artery (RA), the right internal thoracic artery (RITA), and the gastroepiploic artery (GEA) in reference to the conventionally harvested saphenous vein (CON-SV). The primary outcome was graft occlusion, and the secondary outcome was all-cause mortality. RESULTS: A total of 859 studies were retrieved, of which 18 were included. A total of 6,543 patients and 8,272 grafts were analyzed. The weighted mean angiographic follow-up time was 3.5 years. Compared with CON-SV, RA (incidence rate ratio [IRR] 0.56; 95% confidence interval [CI], 0.43-0.74) and NT-SV (IRR 0.56; 95% CI, 0.44-0.70) demonstrated lower graft occlusion. NT-SV and RA were ranked as the best conduits (rank score for NT-SV 0.88 vs. 0.87 for RA, 0.29 for GEA, 0.27 for CON-SV, and 0.20 for RITA). There was no significant difference in late mortality between different conduit types. CONCLUSION: RA and NT-SV are associated with significantly lower graft occlusion rates and are comparably ranked as the best conduit for patency.

Techniques and Outcomes of the No-Touch Vein Conduit as a Y-Composite Graft.

Although the saphenous vein is a widely used conduit for coronary artery bypass grafting, revascularization using the saphenous vein as an aortocoronary bypass graft has shown disadvantages of lower long-term graft patency rates and subsequently worse clinical outcomes, compared with revascularization using the internal thoracic artery. Of the various efforts to overcome the limitations of vein conduit that are resulting from structural and functional differences from arterial conduit, recent technical improvement in no-touch vein composite graft construction and outcomes of revascularization using no-touch vein composite grafts based on the left internal thoracic artery will be discussed in this topic.

Early and Midterm Outcomes of "No-Touch" Saphenous Vein Grafts in Japanese Institutions.

INTRODUCTION: There have been several attempts to overcome the poor graft patency of saphenous vein grafts. "No-touch" saphenous vein graft (NT-SVG) could be a solution to improve graft patency. We aimed to investigate the early and midterm outcomes of coronary artery bypass grafting (CABG) using NT-SVGs in our hospitals. METHODS: This is a retrospective study of 105 patients who underwent CABG using 130 NT-SVGs between August 2013 and December 2021. NT-SVGs were harvested with about a 5-mm margin of surrounding tissue on both sides of the vein with minimal manipulation. Then, the NT-SVG was dilated by natural arterial pressure without manual distension. After surgery, most of NT-SVGs were assessed by cardiac catheterization or multidetector computed tomography (MDCT) to determine early graft patency. Late graft assessments by MDCT were performed about every five years after surgery. RESULTS: The early graft patency of NT-SVGs was 100% (125/125); however, two cases of graft twisting were found. Both cases spontaneously resolved. Leg wound infections of NT-SVG harvesting site were seen in 6.2% of patients. Peripheral neuropathy of the legs such as skin numbness and tingling were frequently observed, which lasted up to one year, but no more than two years after surgery. The midterm graft patency of NT-SVGs was excellent (five-year patency of NT-SVGs was 95.8%). CONCLUSION: The early and midterm graft patency of NT-SVGs was satisfactory. Although leg wound complications can be seen on the harvesting NT-SVG site, the "no-touch" harvesting technique of SVG could improve graft patency and clinical outcomes of CABG.

Towards Endoscopic No-Touch Saphenous Vein Graft Harvesting in Coronary Bypass Surgery.

The saphenous vein is the most used conduit for coronary artery bypass surgery. However, the patency rate of this graft is inferior to the internal thoracic artery patency rate, which is the gold standard. Using the conventional technique, the saphenous vein is harvested via a large open incision and excised in such a way that causes both vascular damage and wound healing complications. Consequently, vein graft patency and surgical site infection may be compromised. Graft patency is markedly improved when the saphenous vein is harvested atraumatically with minimal damage and with surrounding cushion of perivascular fat intact. However, despite the improved graft performance, wound healing complications and infection remain a problem. Although wound healing complication is reduced when using endoscopic vein harvesting, there may be a negative impact on graft performance. This is due to vascular damage associated with application of forces to the vein that are usually avoided in open vein harvesting, including traction, adventitial stripping, and venous compression. There is evidence to suggest that improved patency of endoscopically harvested saphenous veins is associated with the surgeon's experience of the technique. Recently, endoscopic methods of harvesting have been described where the saphenous vein is removed intact and with minimal vascular damage caused. In addition, wound healing complications, infection, and scarring are reduced. While the effect of these techniques on vein graft patency have yet to be reported, the ability to obtain a superior graft with reduced wound complications will be of great benefit to patients undergoing coronary revascularization procedures.

Morphological Changes in Endothelial Cell Organelles in a No-Touch Saphenous Vein Graft.

INTRODUCTION: Improved long-term patency of the no-touch (NT) saphenous vein graft has been reported to result from the preservation of a healthy vascular microstructure, especially endothelial cells. However, the precise morphology of endothelial cells and their organelles in NT saphenous vein graft has not been fully investigated. In this study, we assessed the ultrastructure of preserved endothelial cells in saphenous vein graft using transmission electron microscopy. METHODS: Intact control (IC) vein, NT saphenous vein graft, and conventional (CT) saphenous vein graft were harvested from a patient. After observation by light microscopy, the nuclei and mitochondria in the preserved endothelial cells were compared among IC, NT, and CT using transmission electron microscopy, and the endothelial organelles were assessed quantitatively. RESULTS: Light microscopy showed that the preservation of endothelial cells was comparable in IC, NT, and CT. Subsequent transmission electron microscopy observation showed that the nuclei in preserved endothelial cells appeared more swollen in CT than that in NT. Quantitative analysis revealed that nuclear size and circularity of preserved endothelial cells in NT and IC were similar, but those in CT were larger and higher, respectively, than those in IC and NT. In addition, the mitochondrial size in preserved endothelial cells in CT was larger than that in IC and NT. CONCLUSION: Necrotic changes in endothelial organelles characterized by swelling of nuclei and mitochondria were prominent in CT saphenous vein graft. The normally maintained ultrastructure of preserved endothelial cells in NT saphenous vein graft could contribute to long-term patency.

The No-Touch Saphenous Vein Harvesting Improves Graft Patency After Off-Pump Coronary Artery Bypass Surgery: A Propensity-Matched Analysis.

INTRODUCTION: This single-center study of propensity-matched data was performed to assess the effect of the no-touch saphenous vein (NTSV) harvesting technique on early- and long-term outcomes of patients after off-pump coronary artery bypass grafting (OPCABG) in China. METHODS: A retrospective analysis of 767 patients who underwent OPCABG in the Beijing Anzhen Hospital (June 2017 to October 2021) was performed, and their data entered the conventional saphenous vein (CSV) harvesting technique group or the NTSV group. In-hospital and follow-up outcomes were evaluated by adjusting baseline characteristics using propensity score matching (1:1). Clinical outcomes and postoperative angiographic results were compared. RESULTS: The saphenous vein graft patency rates at postoperative three months and one year for the NTSV group vs. CSV group were 99.6% vs. 96.2% (P<0.001) and 97.3% vs. 93.1% (P<0.001), respectively. The two matched groups received a significantly different cumulative incidence function of saphenous vein graft occlusion for the longer follow-up period in Kaplan-Meier curves (χ=4.330, log-rank P=0.037). No difference in early- and long-term mortality or major adverse cardiac and cerebrovascular events (MACCE) were observed between the groups. The rate of MACCE was not statistically significant different between the groups, but there was a tendency favoring the no-touch technique (9.8% CSV vs. 4.8% NTSV; P=0.067). More patients in the NTSV group developed postoperative leg wound exudation (5.4% vs. 1.2%; P=0.032) and skin numbness (22.2% vs. 8.9%; P=0.001) than in the CSV group. CONCLUSION: The NTSV is an excellent conduit to be used in OPCABG. There remains a need to reduce leg wound complications.

Quality of Life After Percutaneous Coronary Intervention in No-Touch Saphenous Vein Grafts is Significantly Better Than in Conventional Vein Grafts.

OBJECTIVE: To compare health-related quality of life (HRQoL) of patients primarily treated with a no-touch saphenous vein graft with that of patients who received a conventional graft. METHODS: The study included all individuals treated with a percutaneous coronary intervention (PCI) on a saphenous vein graft (SVG) between January 2006 and June 2020. The RAND-36 health survey was used to assess HRQoL. The Mann-Whitney U test was used to test differences in HRQoL between the two groups. Effect size was estimated via Cohen's d. The average treatment effect between the groups was tested by propensity score matching (PSM). RESULTS: Of the 346 patients treated with a PCI in a stenosed or occluded SVG, 165 responded to RAND-36 (no-touch: n=48; conventional: n=117). Patients with a no-touch graft reported better mean values on seven of the eight health survey domains. Statistically significant differences were observed for four of the domains, all in favour of the no-touch group. The effect size estimates indicated a small difference for five domains, with the highest values (>0.40) seen for the general health and energy/fatigue domains. PSM confirmed a statistically significant difference for the physical functioning and general health domains. CONCLUSION: At a mean follow-up of 5.4 years, patients who received a PCI in no-touch vein grafts showed significantly better HRQoL than those who received a PCI in conventional vein grafts.

Adventitial Collagen Cross-Linking by Glutaraldehyde Reinforcing Human Saphenous Vein - Implication for Coronary Artery Bypass Grafting.

INTRODUCTION: A weak venous wall is one of the major reasons contributing to vein graft failure after coronary artery bypass grafting (CABG). We investigated whether adventitial collagen cross-linking by glutaraldehyde reinforces venous wall, preserving the endothelium of veins during high-pressure distention. METHODS: Human saphenous veins (SVs) were collected from 40 patients undergoing CABG, and adventitia cross-linking was performed with 0.3% glutaraldehyde for five minutes. The cross-linked SVs were accessed by biodegradation assay, immunofluorescent staining, and tensile test. Native SVs and cross-linked SVs from another 20 patients received the 200 mmHg pressure distention for two minutes. Pressure-induced injury of SVs were accessed by immunohistochemistry and electron microscopy. RESULTS: Time to digestion was 97±13 minutes for native SVs and 720±0 minutes for cross-linked SVs (P<0.05). After adventitial cross-linking, the collagen I fibres of the vein remarkably presented with compact and nonporous arrangement. In the high-stretch region (stretch ratio 1.4-1.8), the Young's elastic modulus of stress-stretch ratio curve in cross-linked SVs was larger than that in native SVs (13.88 vs. 5.83, P<0.05). The cross-linked SVs had a lower extent of endothelial denudation without fibre fracture during high-pressure distension than native SVs. Comparing with the non-cross-linked SVs, the percentage of endothelial nitric oxide synthase staining length on the endothelium of cross-linked SVs was significantly preserved after high-pressure distension (85.2% vs. 64.7%, P<0.05). CONCLUSION: Adventitial collagen cross-linking by glutaraldehyde reinforced venous wall by increasing stiffness and decreasing extensibility of SVs and mitigated the endothelial damage under high-pressure distension.

True Idiopathic Brachial Artery Aneurysm Treated With a Saphenous Vein Graft.

Purpose: The objective of this study is to report a case of a 65-year-old woman who presented with pallor and pain of her left arm secondary to a true arterial brachial aneurysm, which was successfully treated with saphenous vein bypass and embolization of the aneurysm sac. A review of the literature is also presented. Case report: A 65-year-old woman presented with an acute onset of pallor and pain of her left forearm, and hand. On physical examination, there was a pulsatile mass at the forearm. A doppler ultrasound showed a fusiform aneurysmal dilatation of the brachial artery of 23 mm of diameter. A dynamic contrast-enhanced MRI angiogram confirmed a fusiform dilation of the distal brachial artery. The patient was scheduled for open repair. A fusiform 20 x 60 mm aneurysm of the distal brachial artery extending to the cubital fossa was found and a brachial artery to radial and ulnar arteries bypass with interposed reverse right saphenous vein was created. Embolization of the aneurysm sac was performed using Gelita-spon ® (Gelita Medical, Eberbach, Germany). A final angiogram showed an adequate perfusion through the bypass to the hand, and no contrast in the aneurysmal sac. Postoperative course was uneventful with discharge on the fourth postoperative day. Conclusion: Revascularization with autologous saphenous vein graft and exclusion of the aneurysm with local embolization is a good treatment alternative in a patient with symptomatic brachial aneurysm with distal embolization.

A Case of Using No-Touch Saphenous Vein Graft in Redo CABG after Multiple Failed Percutaneous Coronary Interventions.

The modality of repeat revascularization due to late graft failure is a debated topic. The latest available European guidelines recommend redo coronary artery bypass graft (CABG) for cases of extensively diseased and/or occluded grafts and those with diffuse native vessel disease. We present the case of a patient being relieved of recurrent unstable angina pectoris with redo CABG using no-touch saphenous vein grafts after repeated and unsuccessful attempts with percutaneous coronary intervention (PCI). This could be an alternative to PCI in patients with a complex medical history. Teamwork between cardiologists and surgeons is pivotal in deciding the best treatment modality.

Endoluminal interventions versus surgical interventions for stenosis in vein grafts following infrainguinal bypass.

BACKGROUND: Bypass surgery using a large saphenous vein graft, or another autologous venous graft, is a well-recognised treatment option for managing peripheral arterial disease of the lower limb, including chronic limb-threatening ischaemia (CLTI) and intermittent claudication, peripheral limb aneurysms, and major limb arterial trauma. Bypass surgery has good results in terms of limb preservation rates and long-term graft patency but is limited by the possibility of vein graft failure due to stenoses of the graft. Detection of stenoses through clinical and ultrasonographic surveillance, followed by treatment, is used to avoid graft occlusion. The conventional approach to treatment of patients with graft stenosis following infrainguinal bypass consists of open surgical repair, which usually is performed under general anaesthesia. Endoluminal treatment with angioplasty is less invasive and uses local anaesthesia. Both methods aim to improve blood flow to the limb. OBJECTIVES: To assess the effectiveness of endoluminal interventions versus surgical intervention for people with vein graft stenosis following infrainguinal bypass. SEARCH METHODS: The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov to 25 August 2020. SELECTION CRITERIA: We aimed to include all published and unpublished randomised controlled trials (RCTs) that compared endoluminal interventions versus surgical intervention for people with vein graft stenosis following infrainguinal bypass. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed all identified studies for potential inclusion in the review. We aimed to use standard methodological procedures in accordance with the Cochrane Handbook for Systematic Reviews of Interventions. The main outcomes of interest were primary patency, primary assisted patency, and all-cause mortality. MAIN RESULTS: We identified no RCTs that met the inclusion criteria for this review. AUTHORS' CONCLUSIONS: We found no RCTs that compared endoluminal interventions versus surgical intervention for stenosis in vein grafts following infrainguinal bypass. Currently, there is no high-certainty evidence to support the use of one type of intervention over another. High-quality studies are needed to provide evidence on managing vein graft stenosis following infrainguinal bypass.

Geometric reconstruction of a left ventricular aneurysm with coronary artery bypass graft.

Left ventricular aneurysm is a late mechanical complication of untreated acute myocardial infarction. It has become relatively rare since the development of percutaneous cardiac intervention.  Most aneurysms are located at the anterior ventricular wall, and are caused by total occlusion of the left anterior descending artery. Usually, the anterior and apical walls initially become akinetic; this can sometimes evolve into dyskinesia. Thrombus formation is a common finding, since the apical contractility is impaired. This tutorial illustrates the challenging technical aspects of a large thrombus removal, along with the geometric reconstruction of the left ventricular aneurysm and coronary bypass surgery.

Outcomes of Infrainguinal Lower Extremity Bypass Are Superior in Kidney Transplant Recipients Than Patients with Dialysis.

Patients with end-stage renal disease (ESRD) whether on dialysis therapy (DT) or who received a kidney transplant (KT) have previously shown unfavorable surgical outcomes. Little is known about the comparative efficacy and durability of lower extremity bypass (LEB) in those patients. The Vascular Quality Initiative database was explored to identify DT or KT recipients (2003-2016) who had LEB. We included 1,714 bypass procedures; DT: 1,512 (88.2%). Primary patency (PP) at 2 year was comparable between KT and DT groups (PP [95% confidence interval {CI}]: 77.0% [69.7%-82.8%] vs. 80.5% [77.8%-82.9%]; P = 0.212), and the risk-adjusted hazard was similar (adjusted hazard ratio [aHR] [95% CI]: 0.89 [0.61-1.30]; P = 0.540). Amputation-free survival (AFS) at 2 year was more favorable in KT group (AFS [95% CI]: 73.1% [66.3%-78.8%] vs. 48.0% [45.4%-50.6%]; P < 0.001), (aHR [95% CI]: 2.29 [1.62-3.23]; P < 0.001). Patients on DT exhibited a higher risk of mortality than KT recipients (aHR [95% CI]: 2.94 [2.07-4.17]; P < 0.001). This study demonstrated superior limb outcomes in KT recipients than patients on DT after LEB. Despite the comparable PP, the risk of amputation or death was doubled in patients on DT compared with KT recipients. Because both groups were similar in several baseline characteristics, the difference in outcome is likely driven by the positive effect of KT on the physiological milieu of these patients.