Conventional Vein Grafts Research Articles

Superior long-term patency of no-touch vein graft compared to conventional vein grafts in over 1500 consecutive patients

ObjectivesTo evaluate the long-term angiographic patency of saphenous vein grafts (SVG) harvested using the no-touch technique compared to the conventional technique.MethodsThis was a single-center, retrospective, cohort study. The inclusion criteria were individuals who underwent a CABG (coronary artery bypass grafting) between January 1995 and July 2020, and who successively needed a clinically-driven angiography. The primary endpoint was long-term patency. The secondary endpoints were differences in patency based on sub-group analysis (single vs. sequential graft, divided by target vessel).ResultsThe study included 1520 individuals (618 no-touch, 825 conventional and 77 arterial grafts). The mean clinical follow-up time was 8.4 years ± 5.5 years. The patency per patient was 70.7% in the no-touch grafts vs. 46.7% in the conventional grafts (p < 0.001, OR = 2.8). The graft patency was 75.9% in the no-touch grafts vs. 62.8% in the conventional grafts (p < 0.001, OR = 1.8).ConclusionsThe no-touch vein grafts were associated with statistically significantly higher patency at long-term compared to the conventional grafts.Clinical trial registrationNCT04656366, 7 December 2020.

Long-term results of percutaneous coronary intervention in no-touch vein grafts are significantly better than in conventional vein grafts.

Conventional vein grafts have a high risk of thrombosis and early atherosclerosis. Percutaneous coronary intervention (PCI) in conventional vein grafts is associated with a higher incidence of late adverse cardiac events. The aim of this study was to evaluate the long-term results after PCI in saphenous vein grafts (SVG) harvested with the no-touch technique compared to the conventional technique. This was a single-center, retrospective, cohort study, based on data from the Swedeheart register. The inclusion criterion was individuals who underwent CABG using different vein graft techniques between January 1992 and July 2020, and who required a PCI in SVGs between January 2006 and July 2020. The primary end point was long-term in-stent restenosis. The secondary endpoints were long-term major adverse cardiac events (MACE) and 1-year re-hospitalization rates. The associations between the graft types and the endpoints were evaluated using the Fine and Gray competing-risk regression analysis. The study included 346 individuals (67 no-touch, 279 conventional). The mean clinical follow-up time was 6.4years with a standard deviation of 3.7years. The long-term in-stent restenosis rate for the no-touch grafts was 3.2% compared to 18.7% for the conventional grafts (p < .01), with a subdistribution hazard ratio (SHR) of 0.16 (p = .010). The long-term MACE rate was 27.0% in the no-touch group and 48.3% in the conventional group (p < .01) with a SHR of 0.53 (p = .017). The short-term results were similar in both groups. Percutaneous coronary intervention in a no-touch vein graft was associated with statistically significantly fewer in-stent restenoses and MACE at long-term follow-up compared to a conventional SVG.

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

ObjectiveTo 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.MethodsThe 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).ResultsOf 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.ConclusionAt 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.

Increased Contractile Function of Human Saphenous Vein Grafts Harvested by "No-Touch" Technique.

Saphenous vein grafts are the most common conduits used for coronary artery bypass grafting (CABG); however, no more than 60% of vein grafts remain open after 10 years and graft failure is associated with poor clinical outcome. The “no-touch” harvesting technique—where a sheet of perivascular tissue is retained around the vein—improves graft patency to over 80% after 16 years of follow-up, but the mechanism for the improved patency rate is unclear. In this study, we investigated acute functional differences between vein grafts harvested conventionally and by “no-touch” technique and explored the importance of perivascular tissue for reducing surgical trauma, minimizing excessive distension, and releasing vasoactive paracrine factors. Segments of human saphenous veins were obtained from CABG surgery and their functional properties investigated by isometric and isobaric myography. We found a broad diameter-tension relationship for human saphenous veins, with peak capacity for active tension development at diameters corresponding to transmural pressures around 60 mmHg. Across the investigated transmural pressure range between 10 and 120 mmHg, maximal tension development was higher for “no-touch” compared to conventionally harvested saphenous veins. Contractile responses to serotonin, noradrenaline, and depolarization induced with elevated extracellular [K+] were significantly larger for saphenous veins harvested by “no-touch” compared to conventional technique. Conventional vein grafts are routinely pressurized manually in order to test for leaks; however, avoiding this distension procedure did not change the acute contractile function of the conventionally excised saphenous veins. In contrast, even though surgical removal of perivascular tissue during conventional harvesting was associated with a substantial decrease in force development, removal of perivascular tissue by careful dissection under a stereomicroscope only marginally affected contractile responses of veins harvested by “no-touch” technique. In conclusion, we show that saphenous veins harvested by “no-touch” technique have greater contractile capacity than veins harvested by conventional technique. The different capacity for smooth muscle contraction is not due to vasoactive substances released by the perivascular tissue. Instead, we propose that the larger tension development of saphenous veins harvested by “no-touch” technique reflects reduced surgical damage, which may have long-term consequences that contribute to the superior graft patency.

Highly flexible nitinol mesh to encase aortocoronary saphenous vein grafts: first clinical experiences and angiographic results nine months postoperatively

Saphenous vein graft patency is frequently limited by degeneration. Experimental studies have indicated that rigid external support of venous grafts by a flexible, tubular nitinol mesh may improve graft patency. The study presented was part of a prospective, randomized, multicenter first-in-man trial investigating the safety and effectiveness of nitinol-supported venous grafts in coronary artery bypass graft (CABG) surgery. From our clinic, 25 subjects with multivessel coronary artery disease requiring saphenous vein graft CABG of the right coronary artery (RCA) and the circumflex artery were entered into the trial. Subjects were randomized to receive a mesh-supported graft on one of these arteries; the other vessel received an untreated vein graft. Graft patency was assessed by coronary angiography nine months after surgery. The implantation of mesh grafts was simple and safe. In 10 cases, a nitinol mesh-supported venous graft was anastomosed to the circumflex artery and in 15 cases to the RCA. All patients survived the observation period. A total of 72% of the patients underwent control coronary angiography. The patency rate of mesh-supported grafts was 27.8% nine months postoperatively. Conventional vein grafts showed an 85.7% patency, and arterial grafts had a 100% patency. No complications directly related to the implantation of mesh-supported grafts were observed. The promising experimental results of mesh-supported venous grafts could not be reproduced in the study presented. A critical item seems to be correct selection of nitinol mesh diameter, the anastomotic method and fixation of the mesh tube to the venous graft.

Laser-Assisted Venous Anastomosis: A Comparison Study

A low-powered carbon dioxide laser was used to perform 25 vein grafts (50 anastomoses) on the femoral veins of Sprague-Dawley rats. The patency rate, clamp time, and bleeding time were compared with 50 conventional microvascular vein grafts (100 anastomoses). The patency of the laser-assisted anastomoses (LAVA) was 84 percent, while the conventional vein grafts yielded a 94 percent patency rate. The average clamp time and bleeding time for the LAVA were 47.2 min and 4.88 sec, respectively, while the conventional anastomoses required 57.6 min and had an average bleeding time of 9.44 sec. Histologically, both specimens healed at the same rate, but the laser-assisted anastomoses produced less inflammation and granulation tissue. These results suggest that the laser has potential as a tool for clinical application in microsurgery. In addition, the 94 percent patency rate achieved with the vein interposition graft would suggest that a decrease in the tension across the anastomosis can improve patency.

Results of coronary artery endarterectomy and reconstruction

Since 1978, 5005 patients have had coronary artery bypass operations: 50% had conventional grafts only (group A), 25.1% required one coronary artery endarterectomy (group B), and 24.9% required multiple endarterectomies (group C). Operative mortality and long-term survival were stratified within each group according to the presence of additional risk factors: severe left ventricular dysfunction, repeat operation, insulin-dependent diabetes mellitus, female sex, and age over 70 years. Operative mortality was 4.0% in group A patients, 6.3% in group B, and 10.4% in group C; it increased in each group as the number of risk factors increased. Mortality was higher in patients with a left coronary artery endarterectomy compared to those with a right coronary endarterectomy only when multiple risk factors were present. Perioperative myocardial infarction occurred in 5.6% of group A patients, 6.5% of group B, and 13.1% of group C patients. Early graft patency (940 patients, 18.8%) was 801 of 901 (88.9%) for endarterectomy grafts and 2939 of 3248 (90.5%) for conventional grafts. Late patency (over 1 year) in 288 symptomatic patients was 137 of 191 (71.1%) for endarterectomy grafts and 644 of 850 (75.8%) for conventional vein grafts. Long-term (5-year) actuarial survival rate was reduced in patients requiring endarterectomy. Current anginal status is available for 3011 of 3305 patients (91.1%): 28.9% of group A patients, 32.5% of group B, and 33.7% of group C patients have recurrent angina at an average follow-up of 58.3 months. The results of this study show increased operative mortality and morbidity in patients requiring coronary artery endarterectomy and reconstruction. However, the early results and particularly the late survival, clinical status, and continued graft patency justify this approach in patients with diffuse coronary artery disease, many of whom would otherwise be inoperable.

Patency and Flow Response in Endarterectomized Coronary Arteries

Ninety patients, operated on from May, 1978, through June, 1979, underwent coronary endarterectomy and early recatheterization. Patency of grafts to endarterectomized arteries was 103 of 118 (87.3%) and patency of conventional vein grafts in the same patients was 217 of 233 (93.1%). Myocardial blood flow using xenon 133 washout, at rest and with isoproterenol-induced stress, was measured in 7 normal coronary arteries, 28 conventional saphenous vein grafts, and 33 saphenous vein grafts to endarterectomized coronary arteries. The increase in myocardial blood flow, from rest to isoproterenol-induced stress, was comparable for the three groups. The endarterectomized group was divided further by separating out the 10 patients with heavy scarring or residual disease. The remaining patients had a flow response identical to those with conventional saphenous vein grafts. The rate of perioperative infarction in patients receiving endarterectomy was 3 of 113 (2.6%), as measured by appearance of new persistent Q waves on the serial postoperative electrocardiogram. Positive pyrophosphate scans were noted in 13 of 105 (12.4%) patients. It is concluded that, in the early stages at least, grafts to endarterectomized coronary arteries stay open and perfuse the myocardium as well as conventional saphenous vein grafts unless the myocardium is heavily scarred or unless residual disease remains.

Sequential Anastomoses in Coronary Artery Grafting: Technical Aspects and Early and Late Angiographic Results

The present study concerns itself with the early and late results obtained with aortocoronary vein grafts containing more than 1 coronary anastomosis per graft. The surgical technique is described in detail and some of the hazards are outlined. It is apparent that the use of side-to-side anastomoses (SSAs) leads to a marked increase in blood flow in the proximal portion of the graft (average flow, 131 ml/min) and also increases the patency rate of the proximal anastomosis. Thus, 3 of 51 SSAs were obstructed on the early angiogram, and only 1 of the 28 SSAs restudied at one year had become occluded. Although the cumulative—early and late—patency rate (55/66, or 83.3%) of the distal end-to-side anastomoses (ESAs) was not significantly better than that usually seen with conventional vein grafts, it is believed that improvement in the technique and greater awareness of some of its pitfalls will further decrease the occlusion rate of distal ESAs. Most occlusions of the ESA appeared related to angulation, which tended to occur in the segment of graft between the proximal and the distal anastomoses. Appropriate modifications in the technique are described that should help to eliminate this difficulty. The use of SSAs also allows for grafting of small coronary arteries which, with the conventional single anastomosis technique, are not usually bypassed in view of the high expected failure rate. Thus, of the 9 SSAs performed to 1 mm arteries and studied on two occasions, 8 remained open early after operation and 7 were still patent a year later.