Technical considerations in saphenous vein bypass grafts to the right coronary artery.

Measurement of the proper length for saphenous vein bypass grafts to the right coronary artery can be complicated by the increase in cardiac volume that takes place when extracorporeal circulation is discontinued. Inadequate or excessive allowance for this increase can cause undue tension on the grafts or troublesome kinking. This report describes an improved method of orienting vein bypass grafts to the right coronary artery which eliminates problems of incorrect measurement.     

Nonreversed saphenous vein grafts for coronary artery bypass grafting

Between August 1985 and December 1988, valvotomized saphenous vein grafts were used in 365 patients undergoing coronary artery bypass grafting (CABG). In this operation, the femoral end of the vein is attached to the aorta and the pedal end is attached to the coronary artery. Vein diameters measured 8 +/- 2 mm at the femoral end, 4.5 +/- 1.2 mm at the knee level, and 3.5 +/- 1.3 mm at the ankle. Ratios between levels were as follows: knee to femoral end, 0.56, and ankle to femoral end, 0.43. The ratio of knee to femoral end was 0.42 in cases with vein midthigh bifurcation. There were 1,310 grafts implanted (3.6 per patient). In 341 patients, CABG alone was performed, and 24 patients had combined procedures: 11 had CABG with mitral valve replacement, 9 had CABG with aortic valve replacement, 2 had CABG with repair of postinfarct ventricular septal defect, and 2 had CABG with automatic defibrillator implantation. Follow-up (up to 3.5 years) was attained in 97% of patients. For various reasons, 34 patients had a second angiogram between 3 and 41 months postoperatively. Of 120 vein grafts, 108 (90%) were patent. At autopsy, 11 patients with 45 vein grafts had 43 patent and clean grafts and two thrombosed. Use of nonreversed saphenous vein for coronary bypass is recommended. It assures a large proximal anastomosis, natural vein bifurcations can be used with fewer proximal anastomoses, better vein-coronary artery size matching is obtained, and the patency rate is satisfactory.     

Thrombomodulin activity on human saphenous vein grafts prepared for coronary artery bypass.

Thrombomodulin, a membrane glycoprotein present on normal vascular endothelium, binds circulating thrombin and is important in protein C activation. These functions contribute to the nonthrombogenic nature of endothelium. Damage during harvest and ex vivo storage of vein grafts may result in dysfunction of this endothelial anticoagulant barrier and possibly contribute to early graft thrombosis. We studied the functional activity and antigenic expression of thrombomodulin on saphenous veins before (initial) and after (harvested) harvest and storage for coronary artery bypass grafting in 15 patients. Also, fresh saphenous vein was studied after mechanical endothelial stripping. After storage for 2.7 +/- 0.6 hours at room temperature in heparinized saline, thrombomodulin functional activity in harvested vein segments was 28% less than initial segments (p = 0.08). Endothelial stripping resulted in a 79% reduction in thrombomodulin activity compared with initial segments (p = 0.04). Immunohistochemical staining confirmed thrombomodulin antigen on vein grafts after harvest and storage, but not on segments stripped of endothelium. Thrombomodulin functional activity and antigenic expression on human saphenous vein grafts is not significantly changed by harvest and relatively short periods of storage at room temperature in heparinized saline.     

Long-term clinical outcomes after coronary artery bypass grafting with pedicled saphenous vein grafts

Background

Coronary artery bypass grafting (CABG) using saphenous vein grafts (SVG) is vitiated by poor long-term patency of the vein grafts. Pedicled SVG harvested with the “no-touch” (NT) technique have demonstrated improved patency and could confer better outcomes. We aim to compare long-term results after CABG where NT or conventional technique was used for vein graft harvesting in a hypothesis-generating registry-based study.

Methods

Two propensity score matched cohorts (1349 patients) undergoing CABG with veins harvested with NT (NTT) or conventional (CT) technique in Sweden over the period 2005–2015 were used to compare long-term outcomes. Mortality, postoperative incidence of coronary angiography and need for reintervention was recorded and multivariable hazard ratios adjusted for risk factors were calculated.

Results

The mean follow-up time (SD) was 6.8 (3.3) years for NTT and 6.6 (3.2) years for CT. The adjusted hazard ratios for death, first angiography and need for reintervention for NTT patients were (95% CI) 0.97 (0.80–1.19), 0.76 (0.63–0.93), 0.91 (0.78–1.05), and 0.91 (0.71–1.17), respectively. Failed grafts were found in 43.2% of NTT patients and 53.6% of CT patients at angiography.

Conclusions

In this study NT grafting was associated with a lower risk for repeat angiography, however no difference could be observed for mortality and need for reintervention. The earlier reported improvements in patency of NT veins could possibly be reflected in an improved clinical outcome during the first 10?years after surgery.

     

Comparative study of aorto-coronary bypass surgery using internal mammary artery grafts and saphenous vein grafts

From April, 1985, through March, 1988, 202 patients had aorto-coronary artery bypass (CABG). In two series of consecutive patients who underwent CABG alone with the saphenous vein (SVG) or the internal mammary artery (IMA), mortality, morbidity and postoperative angiographic findings were compared with two series. The mean number of grafts placed was 1.8 per patient (1 to 4 grafts) in IMA group and 2.2 per patient (1 to 4 grafts) in SVG group. Mortality was 3% in two groups. The intraoperatively mean blood flow of graft to LAD in SVG and the mean blood flow of free end of IMA had no significant difference. The early patency rate (1.5 months) was 96% for 177 grafts in IMA group, 97% for 100 with IMA-LAD anastomosis, and 95% for 221 grafts in SVG group, 97.7% for 88 with SVG-LAD anastomosis. Morbidity was not significantly different. Many reports suggested that the long-term patency rate was good within the IMAG. In conclusion, the usefulness of IMAG in Japanese patients should be more stressed in young patients.     

Coronary artery bypass with freeze-preserved saphenous vein allografts.

Over the past 5 years, 13 patients had coronary artery bypass performed with freeze-preserved saphenous vein allografts. There were no operative deaths or significant morbidity. Six patients were studied postoperatively at 42, 37, 10, 7, 5, and 1 months. Six of 8 grafts were patent with good flow. There were four late deaths; two of these occurred in patients who had concomitant resection of a ventricular aneurysm. Of the 9 surviving patients, 6 (6/9) are asymptomatic and 2 (2/9) have occasional chest pains; the condition of 1 patient (1/9) is unchanged. This experience suggests that free-preserved saphenous vein allografts may be used successfully for coronary bypass when autologous veins and internal mammary arteries are unavailable or insufficient for multiple bypass.     

Intraoperative hemodynamic assessment of gastroepiploic artery and saphenous vein bypass grafts: a comparative study.

OBJECTIVE: Blood flow characteristics of right gastroepiploic artery and saphenous vein conduits were compared during bypass surgery. METHODS: This study is based on a consecutive series of 97 patients undergoing a bypass graft to the right coronary artery, posterior descending artery, or posterolateral branch using either a pediculated right gastroepiploic artery (n = 52) or a saphenous vein (n = 45) bypass graft. Flows and velocity profiles were measured with an 8-MHz pulsed-wave Doppler ultrasound flowmeter. Thorough flow measurements were made (1) after cessation of cardiopulmonary bypass and (2) before chest closure. RESULTS: At the end of cardiopulmonary bypass, flow in the right gastroepiploic artery (59. 0 +/- 6.7 mL/min) did not differ (P =.08) from flow in the saphenous vein (46.1 +/- 2.7 mL/min). Mean trace velocity was 11.9 +/- 0.7 cm/s in the right gastroepiploic artery and 11.6 +/- 0.8 cm/s in the saphenous vein (P =.80), but peak systolic velocity was 29.4 +/- 1.2 cm/s for the right gastroepiploic artery and 23.1 +/- 1.3 cm/s for the saphenous vein (P <.001). Likewise, before chest closure, flow was 57.1 +/- 4.7 mL/min in the right gastroepiploic artery and 46.5 +/- 4.0 mL/min in the saphenous vein (P =.10), mean velocity was 12. 9 +/- 0.7 and 11.6 +/- 0.8 cm/s, respectively (P = .22), and systolic peak velocity was 30.0 +/- 1.2 and 22.3 +/- 1.2 cm/s, respectively (P < .001). CONCLUSIONS: There were no flow differences between right gastroepiploic artery and saphenous vein grafts implanted into the same coronary bed in comparable groups of patients. Waveform shape of the right gastroepiploic artery grafts was characterized by a wider spectral dispersion resulting in a higher maximal frequency.     

Renal transplantation: patients with previous saphenous vein-coronary artery bypass grafts.

2 patients underwent saphenous vein-coronary artery bypass grafting before successful renal transplantation. Both patients were able to undergo appropriate therapy for various complications, which further emphasizes the resilience that these patients can have after adequate coronary revascularization.     

Off-pump coronary artery bypass may decrease the patency of saphenous vein grafts

BACKGROUND: There is concern that a hypercoagulable status is caused after coronary artery bypass grafting without cardiopulmonary bypass (off-pump coronary artery bypass grafting, or OPCAB) and may potentially endanger the patency of the anastomosis. The aims of this study were: (1) to compare 1-year graft patency after OPCAB with that of conventional coronary artery bypass grafting (CABG) and that of on-pump beating CABG; and (2) to demonstrate any differences in patency of various conduits among the three groups. METHODS: We analyzed the results of 122 consecutive OPCAB cases (group 1) compared with those of 65 consecutive conventional CABG cases (group II) and those of 19 consecutive on-pump beating CABG cases (group III). In group I, coronary angiography (CAG) was performed immediately postoperatively and 1 year after surgery. In groups II and III, CAG was performed 1 year after surgery. Graft patency was graded as grade A (excellent), grade B (fair), or grade O (occluded). RESULTS: The average number of distal anastomoses in groups I, II, and III were 3.1 +/- 1.1, 3.7 +/- 0.9, and 3.6 +/- 0.9, respectively. In group I, postoperative CAG was performed in 92% of patients (112/122) before discharge. The patency rate (grade A + B) was 96.4% (162/168) for arterial grafts, and 85.6% (160/187) for saphenous vein grafts (SVG). One-year follow-up CAG was performed in 74% of patients (90/122). The patency rate was 97.8% (132/135) for arterial grafts and 67.9% (106/156) for SVG. In group II, 1-year follow-up CAG was performed in 65% of patients (42/65). The patency rate (grade A + B) was 93.5% (43/46) for arterial grafts and 88.3% (98/111) for SVG. In group III, 1-year follow-up CAG was performed in 89% of patients (17/19). The patency rate (grade A + B) was 100% (19/19) for arterial grafts and 86.8% (33/38) for SVG. CONCLUSIONS: Our results demonstrate that the patency rate ot SVG after OPCAB was significantly lower than that of arterial grafts in the early postoperative CAG (p < 0.001), and was also significantly lower than those of SVG of group II (p < 0.001) and group III (p < 0.01) in the postoperative 1-year CAG, although there was no significant difference in 1-year patency of arterial grafts among the three groups. Our data suggest that a specific perioperative anticoagulant therapy may be advisable in patients undergoing OPCAB with SVG.     

Human saphenous vein allograft bypass grafts: Immune response

Although it has been claimed that allografts of blood vessels might be successful because of minimal immunogenicity, they are subject to frequent and early failure, the cause of which has not been thoroughly investigated. We sought to define the immune response to allograft bypass. In a prospective trial, 40 patients underwent cryopreserved venous allograft bypass. Allograft biopsies were performed at implantation and at allograft explantation in instances of graft failure. Tissues were evaluated in a blinded manner by means of standard histologic examination and paraffin immunohistochemical analysis with monoclonal antibodies against a variety of immune markers. During the 31-month follow-up period, 22 allografts were removed, and 19 were suitable for immunohistochemical study. Of these 19, 6 (32%) had moderate or severe infiltrates, which were evenly distributed throughout the intima, media, and adventitia. Immunohistochemical study of the explants demonstrated all of these infiltrates to be leukocytes (+LCA), which were predominantly activated T lymphocytes (+CD3, CD8, CR3) containing cytotoxic granules (+TIA-1). Macrophages were uncommon (+CD68); B cells (+L26, CD79) and natural killer cells (+CD56) were rare. Immunosuppression was associated with decreased presence of cytotoxic granules (TIA-1). Human venous allografts are immunogenic and prompt a T cell–mediated response. Allografts also fail without strong evidence of rejection, presumably because of local injury, hypercoagulability, or stasis. It may be possible to modify the contribution of rejection to venous allograft failure by means of immunosuppression and to modify the contribution of local hypercoagulability by means of anticoagulation. (J Vasc Surg 1998;27:492-9.)     

Follow-up of patients with saphenous vein bypass grafts for angina pectoris.

These studies are in agreement with others that aortocoronary vein grafts done for severe angina pectoris are associated with a low operative and late mortality rate. Most patients were significantly improved in regard to pain and exercise tolerance. "Optimal" graft site is associated with a graft patency rate of about 90 per cent. There is clear evidence that left ventricular function, particularly with exercise, is improved in some patients. When a graft is placed in an obstructed coronary artery supplying a segment of abnormally contracting myocardium, there frequently is significant improvement of contraction when the graft remains patent.     

Patency of sequential and individual saphenous vein grafts after off-pump coronary artery bypass grafting

Abstract Background: The impact of the grafting techniques (individual or sequential grafts) on the graft patency of off‐pump coronary artery bypass grafting (OPCAB) has not been reported. The mid‐term patency rates for individual and sequential saphenous vein grafts (SVGs) as coronary bypass conduits of OPCAB were compared. Methods: A total of 714 distal coronary anastomoses on 448 SVGs were assessed using a 64‐multislice computed tomography in 398 patients at an average of 26.4 ± 23.6 months (three months to five years) after an OPCAB procedure. The blood flow of grafts in the proximal segment of individual and sequential SVGs was also compared. Results: The overall patency of sequential SVGs (95.9%) was significantly superior to individual ones (90.6%, p = 0.022). The anastomoses on the sequential conduits had better patency (95.1% vs. 90.1%, p = 0.013). The patency of side‐to‐side anastomoses (97%) was better than that of end‐to‐side anastomoses (93.1%) and also better than that of the individual end‐to‐side anastomoses (90.1%, p = 0.002, p = 0.041). No significant difference was observed between the two approaches in regard to the three major coronary systems; however, anastomoses on sequential grafts had superior patency to those on individual grafts in the right coronary system (p = 0.008). The blood flows of double and triple sequential SVGs were significantly higher than those of individual ones (p < 0.001, p = 0.048, respectively). Conclusions: The mid‐term patency of a sequential SVG conduit after OPCAB is excellent and generally superior to that of an individual one. (J Card Surg 2010;25:633‐637)