Resumo em Inglês:

ABSTRACT 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.

Resumo em Inglês:

ABSTRACT 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.

Resumo em Inglês:

ABSTRACT 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.

Resumo em Inglês:

ABSTRACT 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.

Resumo em Inglês:

ABSTRACT 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.

Resumo em Inglês:

ABSTRACT 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.

Resumo em Inglês:

ABSTRACT 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.

Resumo em Inglês:

ABSTRACT The no-touch saphenous vein with surrounding pedicle tissue harvesting technique preserved endothelium and vessel wall integrity and demonstrated improved long-term saphenous vein conduit patency that was comparable to internal thoracic artery conduit patency. Despite improved saphenous vein conduit patency rates, there is a possibility that no-touch saphenous vein harvest may increase wound complication rates by increased tissue disruption, including venous and lymphatic channels. Comprehensive strategies to minimize leg wound complications after no-touch saphenous vein harvest are discussed.

Resumo em Inglês:

ABSTRACT 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 (χ2=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.