ABSTRACT
Background
The quality of saphenous vein (SV) grafts can vary depending on the site from which they are harvested. However, few studies have compared SV grafts harvested from the thigh with those harvested from the calf to explore which is more appropriate for use in coronary artery bypass grafting (CABG). In this study, we evaluated the graft patency rates of thigh and calf SV grafts over 5 years. We also assessed the functional and structural viability of SV endothelial and smooth muscle cells.
Methods
This retrospective observational study included 265 patients who underwent CABG performed by the same surgical team between 2015 and 2019. Each patient received one SV graft from either the thigh or the calf to the right coronary territory. The 1‐, 3‐, and 5‐year postoperative coronary computed tomography (CT) angiography results were compared between patients who received the thigh and calf SV grafts. Surgical specimens were collected from 2015, which were evaluated by western blotting and immunohistochemistry to evaluate the expression, stability, morphology, and localization of von Willebrand factor (vWF), matrix metalloproteinase (MMP)‐2, MMP‐9, vimentin, and caveolin‐1 (CAV‐1).
Results
The 5‐year coronary CT angiography results demonstrated a significantly higher patency rate for thigh SV grafts than for calf SV grafts (69.2% vs. 51.7%, p = 0.030). The protein expression of vWF, MMP‐2, MMP‐9, vimentin, and CAV‐1 was significantly higher in calf SV grafts than in thigh SV grafts (all p ＜ 0.05).
Conclusions
In this study, thigh SV grafts had significantly higher patency than calf SV grafts at 5 years after CABG. Moreover, the functional and structural viability of SV endothelial and smooth muscle cells in the thigh SV grafts were better preserved than those in the calf SV grafts. These findings suggest that thigh SV grafts appear to be more appropriate conduits than calf SV grafts for CABG.
Keywords: calf, caveolin, coronary artery bypass grafting, graft disease, metalloproteinase, saphenous vein, thigh, vimentin, von Willebrand factor
1.
Coronary artery bypass grafting (CABG) is one of the most crucial treatments for coronary artery disease (CAD) [1, 2]. Transplantation of the left internal thoracic artery (LITA) to the left anterior descending artery has long been the gold standard method for CABG [3]. However, radial artery (RA) and saphenous vein (SV) segments are also widely used as conduits in CABG [4].
The surgical results of CABG depend mainly on the quality of the native arteries and the implanted aortocoronary conduits [5, 6]. The long‐term prognosis of these grafts varies between studies [7, 8]. Many studies have claimed that the RA is the second‐best graft [9]; however, since the no‐touch (NT) technique has become more widely used, an increasing number of studies are favoring the SV as a conduit in CABG. The SV is harvested intact with its pedicle of perivascular adipose tissue [10]. For a long time, researchers have strived to improve graft harvesting technology to maintain the integrity of the venous intima, and it has been discovered that the quality of SV grafts can be improved by preserving viable endothelial cells (ECs) and smooth muscle cells (SMCs) in the SV harvested for coronary revascularization [11]. However, no studies have compared the surgical results between the SV harvested from the thigh and the SV harvested from the calf in terms of EC and SMC preservation and graft patency. As a result, the choice of whether the SV graft is harvested from the upper or lower leg is based on each surgeon's experience.
This study aims to fill this gap in knowledge. Herein, we retrospectively reviewed the data of patients who underwent CABG using SV grafts harvested from the thigh or calf and implanted to the right coronary territory. The aim of this study is to identify the most appropriate SV conduit for CABG by comparing the patency rates of SV grafts harvested from the thigh and calf within 5 years after CABG. Additionally, we evaluated the viability and functionality of SV ECs and SMCs obtained from these two different locations of the lower limb using western blotting and immunohistochemistry.
2. Materials and Methods
The study protocol was reviewed and approved by The First Affiliated Hospital of Nanjing Medical University. NT SV grafts were harvested according to a standard surgical protocol, and samples were collected in accordance with the protocol, allowing for the use of excess tissue during surgical treatment, as approved by the Institutional Review Board of The First Affiliated Hospital of Nanjing Medical University. All participants provided written informed consent before the procedure. For older patients who were not cognitively capable of providing written informed consent, written informed consent was obtained from the patient's guardian.
2.1. Study Design
Overall, 265 patients who underwent isolated off‐pump CABG, with all cases performed by one surgical team at The First Affiliated Hospital of Nanjing Medical University, between July 2015 and August 2019 were included in this study. This surgical team routinely uses the SV harvested from the calf as a bridge vessel, only harvesting the SV from the thigh as a conduit for the right coronary artery when the calf SV has been used for left coronary revascularization.
Patients who met the following criteria were eligible: aged > 60 years and with at least three‐vessel CAD involving right coronary artery stenosis. The exclusion criteria were emergency surgery, patients with allergy to contrast media, bilateral varicose veins, or previous vein stripping. Each patient underwent CABG to the right coronary artery territory.
Totally, 68 SV specimens, including 34 from the thigh and 34 from the calf, were harvested for protein expression analysis. The thigh and calf SV segments harvested for aortocoronary grafting were at least 2 cm in length. Then, the 2‐cm segments were cut into 1‐cm segments and fixed with 10% formaldehyde solution before being frozen in liquid nitrogen. The samples were transported to our laboratory close to the operating room for further processing.
2.2. Surgical Procedure
SV harvesting was performed by two surgeons with at least 5 years of experience in coronary surgery. The surgeons cut the skin and subcutaneous tissue along the SV avoiding damage to the SV wall and outer membrane, and the front of the SV was marked using methylene blue (Figure 1). Keeping the pedicle of surrounding fat tissue intact, the SV was dissected using an ultrasound knife without touching (NT technique) and dilation in all cases, and left in situ until after heparinization.
Figure 1.
(A) Methylene blue was used to mark the front of the SV after exposure of its full length. (B) The pedicle of the SV was excised away from the surrounding tissue using the ultrasound knife. (C) The SV in the calf. (D) The SV in the thigh. [Color figure can be viewed at wileyonlinelibrary.com]
The proximal great SV was removed and marked with a Bulldog clamp after heparinization. During CABG, the distal end of the SV was first anastomosed to the ascending aorta to dilate the conduit by arterial pressure, with the purpose of localizing and closing the bleeder. Complete revascularization was achieved using single and sequential grafts to the coronary arteries with > 60% stenosis. Once hemodynamic stabilization was achieved, graft flow data were collected by an ultrasonic transit‐time flowmeter (VeriQ System; Medistim, Oslo, Norway).
2.3. Computed Tomography (CT) Angiography Assessment
Patients who died, refused to undergo further follow‐up, or who developed renal impairment were excluded from the data analysis at each stage. We reviewed the 1‐, 3‐, and 5‐year postoperative coronary CT angiography data (Somatom Definition dual‐source scanner; Siemens Medical Solutions, Forchheim, Germany). The corresponding author of this study and two radiologists reviewed all images independently and a consensus was reached. A graft was judged to be occluded when there was no contrast media opacification. When luminal narrowing was > 50%, the graft was considered to be significantly stenotic.
2.4. Western Blotting
PROTEIN EXTRACTION. All protein extraction procedures were performed on ice. Thirty milligrams of SV was cut into small pieces and suspended in 300 mL radioimmunoprecipitation assay lysis buffer (Beyotime, Shanghai, China) containing 6 µL protease inhibitor cocktail (Servicebio, Wuhan, Hubei, China). The tissue was left to stand for 20 min and then homogenized for 10 s three times using a homogenizer (Servicebio) at 30‐s intervals for cooling. The supernatant was collected by centrifuging for 20 min at 16,000g at 4°C and subsequently heating at 100°C for 3 min after adding 300 µL SDS‐PAGE sample loading buffer (Beyotime).
ELECTROPHORESIS. The proteins were resolved on 7.5%, 10%, or 12% SDS‐PAGE gels and electroblotted onto polyvinylidene difluoride membranes (Merck KGaA, Darmstadt, Germany). The membranes were washed with blocking solution (Beyotime) for 30 min at room temperature and incubated with anticaveolin‐1 (CAV‐1), antiglyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), antivimentin, antimatrix metalloproteinase (MMP)‐2, anti‐MMP‐9, and antivon Willebrand factor (vWF) antibodies (1:1000) for 12 h at 4°C with agitation. GAPDH protein expression was used as an internal reference to calculate the relative expression of each of the other proteins of interest. Afterwards, the membranes were washed three times (15 min each) in Tris‐buffered saline Tween 20 (TBST) and incubated with horseradish peroxidase‐conjugated secondary antibodies (1:1000; Beyotime) for 2 h at room temperature with agitation. The membranes were washed again three times (15 min each) in TBST. The protein bands were quantified using Image J software (NIH Image J System, Bethesda, MD, US).
2.5. Immunohistochemistry
Immunohistochemistry was performed on 5‐μm sections obtained from the paraffin‐embedded SV blocks. The tissue sections were deparaffinized with xylol and dehydrated in graded alcohol for 10 min. Then, the sections were washed twice (5 min each) with distilled water and placed in a repair box filled with citric acid (pH 6.0) antigen‐retrieval buffer. The antigen retrieval was conducted in a microwave oven. After naturally cooling to room temperature, the sections were washed three times (5 min each) in phosphate‐buffered saline (PBS). Next, the sections were incubated in 6% hydrogen peroxide in methanol to inactivate endogenous peroxidases and washed three times (5 min each) in PBS. After blocking in 3% bovine serum albumin for 30 min at room temperature, the sections were incubated with primary antibody for 12 h at 4°C. Then, the tissue sections were rinsed with PBS and incubated in secondary antibody for 50 min at room temperature. After rinsing with PBS, the sections were developed with the diaminobenzidine tetrahydrochloride (Servicebio) staining kit and counterstained with hematoxylin (Servicebio). Image analysis was performed using Image J software (NIH Image J System).
2.6. Statistical Methods
Continuous data are expressed as the mean ± standard deviation, and categorical data are expressed as absolute number and percentage. The results of the two groups were compared using the χ 2 test or Fisher's exact test for categorical variables and the t‐test for continuous variables. p < 0.05 was considered statistically significant, and p = 0.05–0.10 was considered marginally significant. The type of graft was the main explanatory variable; thus, the primary analysis was restricted to this variable. Other secondary analyses focused on exploratory subgroup analyses to evaluate whether the effect of graft type was homogeneous on different crucial clinical variables. All analyses were performed using SPSS Statistics software (version 21; IBM Corporation, Armonk, NY, US).
3. Results
3.1. Patient Characteristics
Of the 536 consecutive patients who underwent isolated CABG between July 2015 and August 2019 by the same surgical team at our institution, 265 patients (49.4%) met the inclusion criteria and were invited to participate. Eventually, the coronary CT angiography results of 218 patients (82.3%) were available and included in the final analysis. Some patients were lost to follow‐up at 1, 3, and 5 years, the reasons for which are shown in Figure 1. At 1, 3, and 5 years, the total number of patients who underwent follow‐up coronary CT angiography was 218, 173, and 152, respectively. The patient flowchart is shown in Figures 1 and 2.
Figure 2.
Patient flowchart. [Color figure can be viewed at wileyonlinelibrary.com]
Table 1 shows the preoperative demographic and baseline characteristics of the included patients. The thigh SV group consisted of 90 patients (20 women and 70 men) with a median age of 66.5 (range 60.6–80.5) years. The calf SV group consisted of 128 patients (30 women and 98 men) with a median age of 66.2 (range 60.1–80.5) years. There were no significant differences in median age, sex distribution, preoperative diagnosis, New York Heart Association functional class, and risk factors between the two groups at baseline (all p > 0.05; Table 1).
Table 1.
Preoperative demographic and baseline characteristics of the included patients.
| Variables | Total (N = 218) | Thigh (N = 90) | Calf (N = 128) | p value |
|---|---|---|---|---|
| Age, years, mean (SD)/median(range) | 67.3 (4.9)/66.4 (60.1–80.5) | 67.6 (5.3)/66.5 (60.6–80.5) | 67.1 (4.6)/66.2 (60.1–80.5) | 0.507 |
| Male sex, n (%) | 168 (77.1) | 70 (77.8) | 98 (76.6) | 0.834 |
| Preoperative diagnosis, n (%) | 0.758 | |||
| Stable angina | 74 (33.9) | 33 (47.1) | 41 (32.0) | |
| Unstable angina | 115 (52.8) | 45 (64.3) | 70 (54.7) | |
| Myocardial infarction | 29 (13.3) | 12 (17.1) | 17 (13.3) | |
| NYHA classification, n (%) | 0.831 | |||
| Ⅰ | 41 (18.8) | 15 (16.7) | 26 (20.3) | |
| Ⅱ | 113 (51.8) | 46 (51.1) | 67 (52.3) | |
| Ⅲ | 58 (26.6) | 26 (28.9) | 32 (25.0) | |
| Ⅳ | 6 (2.8) | 3 (3.3) | 3 (2.3) | |
| Risk factors, n (%) | ||||
| Hypertension | 154 (70.6) | 65 (72.2) | 89 (69.5) | 0.668 |
| Dyslipidemia | 101 (46.3) | 39 (43.3) | 62 (48.4) | 0.457 |
| Diabetes | 73 (33.5) | 24 (26.7) | 49 (38.3) | 0.074 |
| History of stroke | 38 (17.4) | 14 (15.6) | 24 (18.8) | 0.540 |
| Chronic renal failure | 12 (5.5) | 5 (5.6) | 7 (5.5) | 0.978 |
| Smoking | 102 (46.8) | 39 (43.3) | 63 (49.2) | 0.391 |
| Previous PCI | 22 (10.1) | 8 (8.8) | 14 (10.9) | 0.621 |
| Body mass index > 25 kg/m2 | 61 (28.0) | 20 (22.2) | 41 (32.0) | 0.112 |
| LVEF < 0.35 | 21 (9.6) | 11 (12.2) | 10 (7.8) | 0.277 |
Abbreviations: LVEF = left ventricular ejection fraction, NYHA = New York Heart Association, PCI = percutaneous coronary intervention, SD = standard deviation.
3.2. Coronary CT Angiography Assessment
Ultimately, we reviewed the 1‐, 3‐, and 5‐year postoperative coronary CT angiography data of 218 patients (82.3%), 173 patients (65.3%), and 152 patients (57.4%), respectively, owing to patient dropout. The graft characteristics of these patients are shown in Table 2. One year after surgery, the patency rate of thigh SV grafts was slightly higher than that of calf SV grafts, but the difference was not statistically significant (83/90 [92.2%] vs. 112/128 [87.5%], respectively, p = 0.264). The 3‐year coronary CT angiography examination demonstrated that the patency of thigh SV grafts was higher than that of calf SV grafts, with marginal significance (53/71 [74.6%] vs. 62/102 [60.8%], respectively, p = 0.057). At 5 years, the patency of thigh SV grafts was significantly higher than that of calf SV grafts (45/65 [69.2%] vs. 45/87 [51.7%], p = 0.030).
Table 2.
Patency rates of thigh and calf SV grafts at 1, 3, and 5 years after CABG evaluated by coronary CT angiography.
| Grafts | Thigh | Calf | p value |
|---|---|---|---|
| One‐year patency | (n = 90) | (n = 128) | 0.264 |
| 92.2 (83/90) | 87.5 (112/128) | ||
| Three‐year patency | (n = 71) | (n = 102) | 0.057 |
| 74.6 (53/71) | 60.8 (62/102) | ||
| Five‐year patency | (n = 65) | (n = 87) | 0.030 |
| 69.2 (45/65) | 51.7 (45/87) |
Abbreviations: CABG = coronary artery bypass grafting, CT = computed tomography, SV = saphenous vein.
3.3. Protein Expression in ECs and SMCs
Western blots of SV extracts demonstrated notably higher expression of vWF, MMP‐2, MMP‐9, vimentin, and CAV‐1 in the calf SV grafts compared with the thigh SV grafts (all p < 0.05). Figure 3 and Table 3 show the results of the western blotting analysis. Moreover, quantitative analysis of the immunohistochemistry results showed that vWF, MMP‐9, MMP‐2, vimentin, and CAV‐1 expression was significantly lower in thigh SV grafts than in calf SV grafts (all p ＜ 0.05). The results of the quantitative analysis are shown in Table 4, and representative staining is shown in Figure 4.
Figure 3.
Western blotting analysis of SV samples. (A) Representative image of a western blot showing the protein expression of vWF, MMP‐9, MMP‐2, vimentin, and CAV‐1 in SV samples from the thigh and calf. (B) Quantitative representation of relative protein expression in SV samples. CAV = caveolin, C‐1 = SV from the calf of patient 1, C‐2 = SV from the calf of patient 2, GAPDH = glyceraldehyde‐3‐phosphate dehydrogenase, MMP = matrix metalloproteinase, MW = molecular weight, SV = saphenous vein, T‐1 = SV from the thigh of patient 1, T‐2 = SV from the thigh of patient 2, vWF = von Willebrand factor.
Table 3.
Quantitative protein expression in thigh and calf SV samples based on the results of western blotting.
| Variable | SV in thigh (n = 34) | SV in calf (n = 34) | p value |
|---|---|---|---|
| vWF | 0.671 ± 0.310 | 0.983 ± 0.584 | 0.008 |
| MMP‐9 | 0.605 ± 0.410 | 0.845 ± 0.451 | 0.025 |
| MMP‐2 | 0.834 ± 0.333 | 1.150 ± 0.582 | 0.008 |
| vimentin | 0.794 ± 0.375 | 1.147 ± 0.689 | 0.011 |
| CAV‐1 | 0.752 ± 0.385 | 1.002 ± 0.439 | 0.015 |
Note: Protein expression is shown in densitometry units. GAPDH was used as the loading control. Data are mean ± SD.
Abbreviations: CAV = caveolin, GAPDH = glyceraldehyde‐3‐phosphate dehydrogenase, MMP = matrix metalloproteinase, SD = standard deviation, SV = saphenous vein, vWF = von Willebrand factor.
Table 4.
Quantitative protein expression in thigh and calf SV samples based on the results of immunohistochemistry.
| Variable | SV in thigh (n = 21) | SV in calf (n = 21) | p value |
|---|---|---|---|
| vWF | 11.809 ± 5.866 | 17.368 ± 9.079 | 0.024 |
| MMP‐9 | 3.439 ± 1.422 | 4.646 ± 2.060 | 0.033 |
| MMP‐2 | 9.127 ± 3.169 | 11.947 ± 3.180 | 0.006 |
| vimentin | 18.991 ± 3.057 | 20.807 ± 2.685 | 0.048 |
| CAV‐1 | 18.374 ± 2.524 | 22.114 ± 2.664 | ＜0.001 |
Note: Protein expression is shown in densitometry units. Data are mean ± SD.
Abbreviations: CAV = caveolin, GAPDH = glyceraldehyde 3‐phosphate dehydrogenase, MMP = matrix metalloproteinase, SD = standard deviation, SV = saphenous vein, vWF = von Willebrand factor.
Figure 4.
Immunohistochemistry images of protein expression in the SV wall. Representative immunohistochemical images showing the expression of vWF, MMP‐9, MMP‐2, vimentin, and CAV‐1 in SV grafts from the thigh and calf. CAV = caveolin, MMP = matrix metalloproteinase, SV = saphenous vein, vWF = von Willebrand factor. [Color figure can be viewed at wileyonlinelibrary.com]
4. Discussion
In this study, we compared the 1‐, 3‐, and 5‐year patency rates of SV grafts from the thigh and calf and evaluated the expression of vWF, MMP‐9, MMP‐2, vimentin, and CAV‐1 in ECs and SMCs from the SV wall. The results demonstrated significantly higher patency of the thigh SV grafts at 5 years after CABG. Moreover, we observed that the protein expression of vWF, MMP‐9, MMP‐2, vimentin, and CAV‐1 was lower in the thigh SV grafts. Therefore, the lower graft patency of calf SVs appeared to occur in tandem with higher protein expression. Although we did not evaluate the direct association between these observations, it is possible that changes in the expression of these proteins influence graft patency, though this remains to be clarified in future research. From our results on graft patency, we suggest that thigh SV grafts may be more appropriate for use in CABG, and that their ECs and SMCs have more stable protein expression, which may be associated with more stable structure and function.
According to a previous report, one of the most commonly used conduits for CABG surgery is the SV [12]. Historically, the LITA and the RA have been regarded as the primary and secondary conduits, respectively, from the standpoint of patency. However, with the widespread application of the NT technique, the use of the SV has increased and the patency rate of SV grafts has dramatically improved [13, 14]. Although RA patency has been reported to be superior to SV patency in most previous studies, some recent reports have reached contrasting conclusions [15]. Long‐term follow‐up studies have shown that the SV is an excellent conduit when used with the NT technique, with a patency rate similar to that of the RA and comparable to the LITA after CABG [10, 16, 17]. Therefore, we believe that enthusiasm for the SV as a graft in CABG is expected to grow in the future [18].
The prevention and treatment of SV graft failure after CABG continue to puzzle researchers, and great efforts have been applied to overcome this problem. Exuberant intimal hyperplasia, which is characterized by EC and SMC migration and proliferation, and thrombus organization are the major causes of graft occlusion [19, 20]. Despite the notable efforts of clinicians, intraoperative and postoperative vascular injury cannot be entirely avoided. In response to injury, the SMC phenotype changes, characterized by increased vimentin expression. This stimulates the production of extracellular MMPs, which have a unique ability to degrade elastin and collagen [21]. MMP‐2 and MMP‐9 break the basement membrane surrounding SMCs, which hinders migration [22]. During vascular injury, platelet activation and adhesion could be viewed as stress responses. The endothelial surface and circulating glycoprotein vWF regulate platelet adhesion and are associated with thrombotic diseases [23]. vWF binds to glycoprotein Ⅰb alpha and glycoprotein Ⅱb/Ⅲa, promoting the dynamic binding between glycoprotein Ⅱb/Ⅲa and fibrinogen, which is essential for platelet aggregation [24]. An in vitro study showed that vWF formed into thick bundles and meshes that spanned the vessel lumen and bound platelets together, eventually leading to occlusion [25]. Caveolae, which are specialized cell surface plasma membrane invaginations found in ECs and SMCs, are also involved in neointimal hyperplasia, and CAV‐1 is an important component of caveolae [26, 27]. Reports have shown that CAV‐1 regulates angiotensin II‐induced SMC proliferation or migration via the extracellular‐regulated protein kinases or MMP‐9 signaling [28, 29]. Moreover, CAV‐1 has been considered as a sensor of shear stress by ECs and a trigger of subsequent signaling pathways involved in vascular remodeling [30]. Therefore, our findings showing that the graft patency of calf SVs was lower than that of thigh SVs could be related to differences in the expression of the abovementioned proteins between the two types of graft. Specifically, these proteins were more highly expressed in calf SV grafts. The intrinsic biological differences between calf and thigh SVs may be associated with the observed differences in patency rates.
To our best knowledge, this is the first study to show that the patency rate is higher and the expression of the five above‐mentioned proteins is lower in thigh SV grafts than in calf SV grafts. Chronic venous disease is a common condition, with varicose veins affecting up to 40% of the population and up to 4% of elderly patients aged > 65 years suffering from venous ulceration [31]. Long‐term high venous pressure can be caused by many factors, and the calf SV is more frequently involved than the thigh SV due to its low position [32]. Almost all surgeons are inclined to avoid using diseased SV specimens as grafts in CABG, yet some normal‐looking SVs with a trend for impending lesions, especially in the calf, may unknowingly be harvested for coronary revascularization. In such cases, the cellular functional and structural viability of these normal‐looking SV grafts may already be impaired. These changes, which may be indistinguishable to the eye, may be observed as high protein expression in calf SV samples, as shown in the present study.
In clinical practice, it is not often necessary to use the full‐length SV. In such cases, the SV in the thigh may be preferred. Moreover, in certain scenarios, such as lesions in the RA or LITA or a large heart size, where one SV in the thigh may be insufficient, it is likely that the SV in the contralateral thigh would be the first choice instead of the calf SV.
4.1. Study Strengths and Limitations
This study has some strengths and limitations that should be considered. In terms of the study's strengths, the thigh and calf SV were compared between the same patients by western blotting and immunohistochemistry. Therefore, all variables aside from the position of the SV were controlled. Moreover, the two SV conduits were subjected to identical systemic factors, such as hyperlipidemia, diabetes mellitus, and hypertension, which can affect graft patency. CABG was performed by the same surgical team in all cases; therefore, the level of surgical expertise was similar for all procedures.
In terms of the study's limitations, this was a single‐center retrospective study. Therefore, prospective multicenter studies should be performed to validate our results in the future. Furthermore, only 265 patients were enrolled, and only 218 had available coronary CT angiography results at the 1‐year follow‐up, with this number declining even further at the 3‐ and 5‐year follow‐ups, possibly owing to the coronavirus disease 2019 pandemic. Moreover, we only compared relative protein expression among 34 pairs of patients, and only 21 sample pairs were further evaluated by immunohistochemistry. Therefore, future studies should increase the sample size, which would increase the reliability of the conclusions. Finally, we did not perform subgroup analyses, which would be useful to gain additional insights into the factors influencing the differences in graft patency between thigh and calf SV grafts.
5. Conclusions
In conclusion, the protein expression of vWF, MMP‐9, MMP‐2, vimentin, and CAV‐1 was lower in thigh SV grafts than in calf SV grafts, which occurred in parallel with the higher patency rates of thigh SV grafts, although the association between these observations was not directly investigated. The high relative protein expression in calf SV grafts could have predisposed to graft failure postoperatively, which is worthy of exploration in future studies. From our findings of graft patency, we suggest that the thigh SV may be preferred over the calf SV as a conduit for CABG.
Conflicts of Interest
The authors declare no conflicts of interest.
Chen A., and Pan K., “The Thigh Saphenous Vein Versus the Calf Saphenous Vein: Searching for the Optimal Conduit for Coronary Artery Bypass Grafting,” Catheterization and Cardiovascular Interventions 106 (2025): 3665‐3672, 10.1002/ccd.70270.
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