Sequential Saphenous Vein Coronary Bypass Grafting

Surgical Myocardial Revascularization with a Composite T-graft from the Left Internal Mammary Artery-Comparison of the Great Saphenous Vein with the Radial Artery

BACKGROUND

 Composite T-grafts between left internal mammary artery (LIMA) and radial artery (RA) are a common concept in complete arterial myocardial revascularization. The aim of the present study was to investigate whether the use of the great saphenous vein (SV) instead of RA leads to comparably good results in terms of outcome in this context.

METHODS

 Patients who underwent myocardial revascularization with a T-graft using RA or a segment of SV to the right coronary artery or circumflex artery between the beginning of 2014 and the end of 2019 at the Department of Cardiovascular Surgery, University Hospital Schleswig-Holstein, Campus Kiel were included. To minimize surgical variation, only patients were observed by a single senior surgeon in the department. Exclusion criteria were previous cardiac surgery, preoperative extracorporeal circulatory support, off-pump surgery, additional aortocoronary bypasses, and cardiac combination procedures.

RESULTS

 A total of 115 patients were studied. In 55 patients, the T-graft was placed between the LIMA and SV, and in 60 patients, the T-graft was placed between the LIMA and RA. Patients in the SV group were older (70.6 ± 7.8 vs. 58.5 ± 10.0 years; p < 0.001), suffered more frequently from non-ST elevation myocardial infarction (12.7 vs. 1.7%; p = 0.027), arterial hypertension (83.6 vs. 61.7%; p = 0.009), and atrial fibrillation (18.2 vs. 1.7%; p = 0.003). They were less likely to be active smokers (16.4 vs. 38.3%; p = 0.009) and less likely to have a history of variceal surgery (0 vs. 15.0%; p = 0.003). Calcification of the ascending aorta was also found more frequently in the saphenous group (18.2 vs. 3.3%, p = 0.009). Operative times and number of distal anastomoses did not differ significantly between the two groups. Postoperative deliriums (16.7 vs. 5.0%; p = 0.043) were observed more frequently in venous patients. Wound healing disorders of the leg (11.1 vs. 0%; p = 0.011) did only occur in SV group and wound infections of the arm only in the RA group. Complete follow-up was achieved in 74.8% of cases. Median follow-up was 60.3 (39.6; 73.2) months. Serious adverse cardiac-cerebral events (19.0 vs. 22.7%; p = 0.675) and mortality (14.5 vs. 6.7%; p = 0.167) did not differ significantly between the groups at follow-up. Myocardial infarction (0 vs. 2.5%; p = 1.000) and stroke (0 vs. 7.5%; p = 0.245) were observed exclusively in RA group. Percutaneous coronary intervention was required in single patients of RA group (0 vs. 15.0%; p = 0.028). No patient from either group underwent repeat coronary artery bypass grafting (CABG). The patients of SV group had angiographically competent grafts and open anastomoses. Graft failure was noted in a single patient in RA group, in which case both grafts and native coronary vessels were stented. Kaplan-Meier analysis revealed no significant survival disadvantage for SV group compared with RA group.

CONCLUSION

 CABG with a composite T-graft between LIMA and a segment of SV may be comparable to bypass surgery with a composite T-graft between LIMA and RA. This might be true in terms of morbidity and mortality over an intermediate-term observation period. The results of our studies give rise to the hypothesis that the decision not to perform aortic bypass anastomosis may be more important than the choice of graft material.

Are ovine and porcine carotid arteries equivalent animal models for experimental cardiac surgery: A quantitative histological comparison

BACKGROUND

Coronary artery bypass grafting (CABG) is a common cardiac surgery. Manufacturing small-diameter (2-5mm) vascular grafts for CABG is important for patients who lack first-choice autologous arterial, or venous conduits. Ovine and porcine common carotid arteries (CCAs) are used as large animal models for in vivo testing of newly developed tissue-engineered arterial grafts. It is unknown to what extent these models are interchangeable and whether the left and right arteries of the same subjects can be used as experimental controls. Therefore, we compared the microscopic structure of paired left and right ovine and porcine CCAs in the proximodistal direction and compared these animal model samples to samples of human coronary arteries (CAs) and human internal thoracic arteries (ITAs).

METHODS

We compared the histological composition of whole CCAs of sheep (n=22 animals) with whole porcine CCAs (n=21), segments of human CAs (n=21), and human ITAs (n=21). Using unbiased sampling and stereological methods, we quantified the fractions of elastin, total collagen, type I collagen, type III collagen, smooth muscle actin (SMA) and chondroitin sulfate (CS) A, B, and C. We also quantified the densities and distributions of nuclear profiles, nervi vasorum and vasa vasorum as well as the thickness of the intima-media and total wall thickness.

RESULTS

The differences between the paired samples of left and right CCAs in sheep were substantially greater than the differences in laterality in porcine CCAs. The right ovine CCAs had a smaller fraction of elastin (p<0.001), greater fraction of SMA (p<0.01), and greater intima-media thickness (p<0.001) than the paired left side CCAs. In pigs, the right CCAs had a greater fraction of elastin (p<0.05) and a greater density of vasa vasorum in the media (p<0.001) than the left-side CCAs. The fractions of elastin and CS decreased and the fraction of SMA increased in the proximodistal direction in both the ovine (p<0.001) and porcine (p<0.001) CCAs. Ovine CCAs had a muscular phenotype along their entire length, but porcine CCAs were elastic-type arteries in the proximal segments but muscular type arteries in middle and distal segments. The CCAs of both animals differed from the human CAs and ITAs in most parameters, but the ovine CCAs had a comparable fraction of elastin and CS to human ITAs.

CONCLUSIONS

From a histological point of view, ovine and porcine CCAs were not equivalent in most quantitative parameters to human CAs and ITAs. Left and right ovine CCAs did not have the same histological composition, which is limiting for their mutual equivalence as sham-operated controls in experiments. These differences should be taken into account when designing and interpreting experiments using these models in cardiac surgery. The complete morphometric data obtained by quantitative evaluation of arterial segments were provided to facilitate the power analysis necessary for justification of the minimum number of samples when planning further experiments. The middle or distal segments of ovine and porcine CCAs remain the most realistic and the best characterized large animal models for testing artificial arterial CABG conduits.

No-Touch Sequential Saphenous Venous Harvesting Technique in Off-Pump Bypass Surgery: A Retrospective Study

Background

In the mid-1990s, the Swedish expert team proposed saphenous vein graft (SVG) harvesting with pedicle tissue. The short-term and long-term patency rates of the great saphenous vein obtained by the no-touch (NT) were higher than those obtained by the conventional (CON). In the past, NT harvesting was mainly used in on-pump coronary artery bypass grafting (CABG), and vein grafts were mostly single vein grafts. In this study, we retrospectively analyzed the safety and effectiveness of sequential vein grafts using NT harvesting in off-pump CABG.

Methods

From 2017 to 2019, a total of 505 patients were included in the study. There were 150 patients in the NT group and 355 patients in the CON group. After applying propensity score matching (1:1 matching), 148 patients were included in each group. Baseline data, graft patency, post-operative complications, leg wound complications and 1-year major adverse cardiac and cerebrovascular events (MACCEs) were compared between the two groups.

Results

There was no significant difference in the patency rate of sequential venous grafts between the two groups 1 year after the operation either before [NT: 7.1% (10/141) vs. CON: 11.5% (38/331), p = 0.149) or after matching (NT: 7.1% (10/140) vs. CON: 7.3% (9/124), p = 0.971]. There was no significant difference in the composite clinical endpoint between the two groups either before [NT: 3 (2.3%) vs. CON: 9 (2.8%), p = 1.000] or after matching [NT: 3 (2.3%) vs. CON: 3 (2.5%), p = 1.000]. There were differences in leg wound complications between the two groups both before [NT: 9 (6.9%) vs. CON: 6 (1.9%), p = 0.007] and after matching [NT: 9 (6.9%) vs. CON: 2 (1.7%), p = 0.043].

Conclusions

The application of the NT harvesting in off-pump CABG with sequential vein grafts is safe and effective. NT method has disadvantages in leg wound.

The expansion of no-touch harvesting sequential vein graft after off-pump coronary artery bypass grafting

Background and Aim of the Study

Many studies support that the no‐touch (NT) procedure can improve the patency rate of vein grafts. However, it is not clear that the sequential vein graft early expansion in the NT technique during off‐pump coronary artery bypass grafting (CABG). This study will explore this issue.

Methods

This was a prospective single‐center randomized controlled clinical trial. A total of 100 patients undergoing off‐pump CABG with the sequential saphenous graft were randomly assigned to two groups: the NT and conventional (CON) groups. Perioperative and postoperative data were collected during the hospital stay. The mean diameter of sequential grafts was measured using cardiac computed tomography angiography 3 months after the operation.

Results

There was a significant difference in the average diameter of sequential grafts between the two groups (NT: [2.98 ± 0.42], CON: [3.26 ± 0.51], p = .005). There was no difference in occlusion of sequential venous grafts between the two groups (NT: 4/48 [8.3%], CON: 5/49 [10.2%], p = 1.000). There were differences in surgery time between the two groups (NT: 220 [188,240], CON: 190 [175,230], p = .009).

Conclusions

The sequential graft early expansion in the NT technique is not as pronounced as that in the conventional technique, which may have a long‐term protective effect on the grafts.