The back-approach technique of endoscopic saphenous vein harvesting in coronary artery bypass grafting

Abstract

Purpose

One of the concerns during endoscopic saphenous vein harvesting (EVH) in coronary artery bypass grafting (CABG) is injury to the vein or its branches. The cutting edge of bipolar electrocautery scissors, used to divide the side branches of the saphenous vein, can cause vascular injury leading to reduced graft patency. We have developed a novel back-approach technique using a C-ring to divide the wide side branches of the saphenous vein during EVH. The aim of the study was to describe the technique and assess early outcomes of EVH using this technique. The back-approach technique is as follows: (a) insert the C-ring near the target branch, (b) push the C-ring over the proximal aspect of the target branch, (c) twist the C-ring forward to capture the target branch, and (d) cut the target branch by bipolar electrocautery.

Methods

We investigated 169 patients, including 35 women (mean age 70.1 ± 8.9 years), who underwent CABG at our hospital, using a novel EVH technique. The patients were categorized as those who underwent EVH (EVH group, n = 44) or open vein harvesting (OVH) (OVH group, n = 125). This method involves the creation of a small incision (2 cm), sufficient saphenous vein dissection near the skin incision, adequate dissection to separate the vein from the surrounding tissues, and the back-approach technique with C-ring to divide the side branch of the saphenous vein. The primary endpoint was the graft patency rate, and the secondary endpoints were leg wound complications and length of hospitalization.

Results

No significant intergroup difference was observed in early patency of saphenous vein graft patency (OVH vs. EVH = 94.7 vs. 95.6%, p = 0.763). The incidence of lower extremity wound lymphorrhea was significantly lesser (OVH: EVH = 16.0: 0.0%, p = 0.005) and the length of hospitalization was also significantly shorter in the EVH group (OVH vs. EVH = 24.2 ± 9.8 vs. 19.0 ± 5.3 days, p = 0.001).

Conclusions

EVH, using the back-approach technique, showed satisfactory short-term results; therefore, this technique performed with C-ring might be effective for vein harvesting during EVH.

Introduction

Arterial grafts (bilateral or single internal mammary artery, radial artery, and gastroepiploic artery) are increasingly being accepted as conduits for coronary artery bypass grafting (CABG); however, saphenous vein grafts (SVGs) continue to be used regularly. Following technological advances, endoscopic saphenous vein harvesting (EVH) is popularly used as a minimally invasive technique during CABG.

Compared with open vein harvesting (OVH), EVH is associated with short-term advantages including lesser wound morbidity and better cosmetic results [1]. However, several studies have reported that the mid- and long-term patency rates of veins obtained through EVH were significantly lower than those of veins obtained by OVH [2–6], and the lower patency rates could be attributed to technical issues. The cutting edge of bipolar electrocautery scissors, used to divide the relatively wide side branches of the saphenous vein, can cause vascular injury.

We introduced the back-approach technique using a C-ring to divide the side branches of the saphenous vein (Fig. 1) for EVH performed during CABG. The back-approach technique included the following steps: (a) C-ring insertion near the target branch, (b) advancement of the C-ring over the proximal aspect of the target branch, (c) twisting the C-ring forward to capture the target branch, and (d) cutting the target branch using bipolar electrocautery. The aim of the study was to describe the technique and outcomes of a novel back-approach technique using a C-ring to divide the side branches of saphenous vein graft during EVH, in comparison with OVH.

Fig. 1.

The back-approach technique with a C-ring to divide the side branch of the vein. The back-approach technique involves inserting a C-ring near the target branch (a), advancing the C-ring over the proximal aspect of the target branch (b), twisting the C-ring forward to capture the target branch (c), and cutting the target branch using bipolar electrocautery (d)

Subjects and methods

Inclusion and exclusion criteria

We excluded patients who received only an internal mammary artery graft, those who underwent emergency operations, and those with infective complications (body temperature > 37.5 °C and white blood cell > 10,000/μL or C-reactive protein > 3 mg/dL), because they have included leg wound infections. We included patients who underwent only CABG, as well as those who underwent CABG with aortic valve replacement (AVR). Therefore, 169 patients (35 women, mean age 70.1 ± 8.9 years) were included, of which 23 patients underwent CABG with AVR.

Patients

This retrospective study was approved by the Institutional Review Board of Soka Municipal Hospital, and written informed consent was obtained from all of the patients included in this study.

Induction and maintenance of anesthesia were similar in all patients who received weight-related doses of fentanyl, midazolam, and pancuronium bromide. This study was conducted in accordance with the ethical principles stated by the Declaration of Helsinki.

After CABG, all patients received the usual dosage of propofol for sedation until they were weaned from a respirator. To avoid over-sedation, sedation levels were controlled using the Richmond Agitation-Sedation Scale scores [7], which were maintained between 0 and 2 points in all patients admitted to the intensive care unit (ICU). Acetaminophen was used for pain control; the Behavioral Pain Scale scores [8] were maintained at < 5 points in all patients. As per our unit policy, weaning from the respirator was not performed on the day of operation. After weaning from the respirator, the postoperative rehabilitative program was initiated on the first postoperative day.

All patients who fulfilled the standard discharge criteria were transferred from the ICU to the general ward, except patients with indwelling drains and central venous catheters and those who required catecholamine administration.

Methods

Between February 2013 and May 2018, vein harvesting was performed under direct vision, and EVH was introduced at our hospital in June 2018. Therefore, we categorized our study population into an OVH group (n = 125 patients who underwent the procedure during the early study period, 216 grafts) and EVH group (n = 44 patients who underwent the procedure during the latter study period, 73 grafts).

The VasoView Hemopro 2 Endoscopic Vessel Harvesting System (MAQUET Cardiovascular LLC, Bengue, AB) was used for all EVH procedures. This device contains an endoscope (7 mm), a C-ring, and bipolar electrocautery scissors for ligation and division of vessel branches. Bipolar electrocoagulation facilitates dissection and manipulation of side branches of veins. Initially, we inserted a trocar for port placement to introduce the device, after which we inserted a conical dissection cannula to create a tunnel around the vein. We created a seal within the tunnel by inflating a balloon to < 5 mL of air to inflate the balloon at the trocar site port, and carbon dioxide (CO₂) was injected into the tunnel at a pressure of 10 to 12 mmHg. The vein branches were divided using a bipolar electrocautery set to 20 W. Proximal saphenous vein ligation was performed through a small separate stab incision. Veins of an adequate length were removed, and a heparinized solution was injected into the selected veins, to rule out leakage and/or injury. After leakage and/or injury was excluded, the veins were stored in a sterile cup, containing heparinized solution (heparin 100 U/mL), until use. Intraoperative SVG flow was measured using the Veri-Q Color Doppler (MediStim co., Oslo, Norway).

Postoperative coronary artery angiography was performed within 14 days after CABG. In total, 98/125 patients (169 SVGs) in the OVH group and 29/44 patients (50 SVGs) in the EVH group underwent postoperative coronary artery angiography.

Diabetes mellitus (DM) was defined as the recent use of antidiabetic drugs, fasting blood glucose > 126 mg/dL, and/or serum hemoglobin A1c > 6.5%. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate < 50 mL/min/1.73 m².

Endpoint

The primary endpoint was the graft patency rate, and the secondary endpoints were leg wound complications and length of hospitalization.

Statistical methods

Continuous data are expressed as mean ± standard deviation (SD) with ranges. Non-parametric data were analyzed using contingency tables; the Mann-Whitney U test was used. Parametric data were compared using Student’s t test. The chi-squared test was used to analyze data presented in a contingency table. A p value < 0.05 was considered statistically significant. The StatView for Windows software version 6.0 (SAS Institute Inc., Cary, NC) was used for all statistical analyses.

Technique

Our novel method includes the following technical modifications to the EVH procedure:

• (i)A short skin incision (only 2 cm in length) is created for trocar site port placement, because a skin incision measuring > 2.5 cm in length is usually associated with slipping of the trocar side port out of the incision, and adequate CO₂ sealing cannot be maintained. Trocar slippage causes excessive buildup of CO₂ and prolongs the SVG harvest time. Therefore, a small skin incision, that is just adequate for insertion of the trocar site port, is important.
• (ii)Adequate dissection of the saphenous vein near the skin incision, before insertion of the trocar side port, is important to minimize the risk of injury to the vein during insertion of the trocar site port. Therefore, deep dissection of veins should be performed under direct vision. Additionally, ultrasonography should be performed before CABG to confirm the position of the saphenous vein branches.
• (iii)A conical dissection cannula is used for adequate dissection of the vein from the surrounding tissue. Meticulous dissection of membranous tissues surrounding the veins ensures optimal visualization of the side branches and minimizes the risk of injury to the vein. Dissection should be performed carefully (lateral-to-medial, superior-to-inferior) and away from the vein itself.
• (iv)The final step includes the back-approach technique with the use of a C-ring (Fig. 1). This method involves inserting a C-ring near the target branch (a), advancing the C-ring over the proximal aspect of the target branch (b), twisting the C-ring forward to capture the target branch (c), and cutting the target branch using bipolar electrocautery (d). Usually, the C-ring pushes the vein anterior to the branches to avoid injury of the vein. However, the cutting edge of the bipolar electrocautery scissors can cause vein wall injury during division of the relatively wide side branches of the vein. Therefore, when using this technique, we insert the C-ring posterior to the branch and tilt the C-ring to gently capture the branch. The branch gets stretched, and it is easier to cut the target branch using bipolar electrocautery, and the C-ring acts as a protective shield for the saphenous vein against the bipolar electrocautery. In this position, the back-approach technique with a C-ring creates a sufficient distance between the vein and the electrocautery blade to easily cut the side branch. Notably, the C-ring directly protects the vein from the cutting edge of the bipolar electrocautery scissors and enables safe and easy division of the side branches.

Results

This study included 169 patients (35 women, mean age 70.1 ± 8.9 years), of which 23 patients underwent CABG with AVR.

The study groups were matched with regard to preoperative characteristics, such as age, sex, prevalence of hypertension, dyslipidemia, chronic obstructive pulmonary disease, CKD, smoking history (history of smoking within a month prior study enrollment), and serum hemoglobin levels (Table 1), except for the prevalence of DM (OVH vs. EVH = 56.0 vs. 75.0%, p = 0.026). No statistically significant intergroup differences were observed in the operative characteristics (Table 2) and the intraoperative SVG blood flow (OVH vs. EVH = 71.1 ± 37.6 vs. 68.8 ± 38.2 mL/min, p = 0.724).

Table 1.

Demographic characteristics of all patients before interventions

	OVH group (n = 125)	EVH group (n = 44)	p value
Age (year)	70.4 ± 8.6	69.2 ± 9.8	0.445
Sex (female)	23 (18.4%)	12 (27.3%)	0.214
BMI (kg/m2)	23.9 ± 5.3	24.5 ± 4.4	0.510
Prevalence
Hypertension	109 (87.2%)	40 (90.9%)	0.515
Dyslipidemia	103 (82.4%)	38 (86.4%)	0.546
DM	70 (56.0%)	33 (75.0%)	0.026
COPD	27 (21.6%)	5 (11.4%)	0.138
CKD	20 (16.0%)	8 (20.0%)	0.740
PAD	18 (14.4%)	8 (18.2%)	0.553
Smoking within a month	23 (18.4%)	8 (18.2%)	0.975
Hb (g/dL)	13.0 ± 1.9	13.2 ± 1.8	0.515
CRP (mg/dL)	1.0 ± 3.1	0.2 ± 0.3	0.085
EF (%)	58.1 ± 12.0	54.8 ± 14.4	0.139
EuroSCORE II (%)	2.0 ± 1.7	1.8 ± 1.1	0.593

OVH, open saphenous vein harvesting; EVH, endoscopic saphenous vein harvesting; DM, diabetes mellitus; COPD, chronic obstructive pulmonary disease, CKD, chronic kidney disease; PAD, peripheral artery disease; Hb, hemoglobin; CRP, C-reactive protein; EF, ejection fraction

Table 2.

Operative characteristics

	OVH group (n = 125)	EVH group (n = 44)	p value
Number of bypass	3.3 ± 1.0	3.1 ± 1.1	0.391
Number of SVG	1.7 ± 0.5	1.7 ± 0.5	0.389
Number of SVG bypass	2.2 ± 0.9	2.2 ± 1.0	0.585
SVG flow (mL/min)	71.1 ± 37.6	68.8 ± 38.2	0.724
With AVR	17 (13.6%)	6 (13.6%)	0.699
Operative time (min)	433.7 ± 140.3	433.2 ± 112.4	0.981
Circulation time (min)	242.9 ± 129.1	236.1 ± 111.7	0.839
Minimum rectal temperature (°C)	34.6 ± 1.4	34.4 ± 1.0	0.619
Use of IABP	8 (6.4%)	1 (2.3%)	0.297

OVH, open saphenous vein harvesting; EVH, endoscopic saphenous vein harvesting; SVG, saphenous vein graft; AVR, aortic valve replacement; IABP, intra-aortic balloon pumping

Postoperative coronary angiography was performed on all patients with CABG except in those with CKD and/or deterioration of postoperative renal function. No significant intergroup differences were observed in the early SVG patency rates (OVH vs. EVH = 94.7% vs. 95.6%, p = 0.763) (Table 3). However, the incidence of lower extremity wound lymphorrhea was significantly lesser in the EVH group (OVH vs. EVH = 16.0% vs. 0.0%, p = 0.005). No significant intergroup differences were observed in wound infection rates; 6 patients in the OVH group developed lower extremity infections; however, they were successfully treated with wound re-exploration and antibiotics. The length of hospitalization was significantly shorter in the EVH group than in the OVH group (OVH vs. EVH = 24.2 ± 9.8 vs. 19.0 ± 5.3 days, p = 0.001).

Table 3.

Postoperative characteristics

	OVH group (n = 125)	EVH group (n = 44)	p value
Re-sternotomy	6 (4.8%)	0 (0%)	0.141
Mediastinitis	6 (4.8%)	1 (2.3%)	0.472
Atrial fibrillation	37 (29.6%)	11 (25.0%)	0.563
Re-intubation	5 (4.0%)	2 (4.5%)	0.877
Early patency of SVG (%)	94.7% (213/225 bypass)	95.6% (65/68 bypass)	0.763
Infection of lower extremities	6 (4.8%)	0 (0%)	0.141
Lymphorrhea of lower extremities	20 (16.0%)	0 (0%)	0.005
Hospitalization (day)	24.2 ± 9.8	19.0 ± 5.3	0.001
Hospital death	4 (3.2%)	0 (0%)	0.230

OVH, open saphenous vein harvesting; EVH, endoscopic saphenous vein harvesting; SVG, saphenous vein graft

Discussions

In this study, we observed no significant differences in the short-term SVG patency rates between the OVH and EVH groups. Compared with the OVH group, the EVH group showed a significantly lesser incidence of lower extremity wound lymphorrhea. Moreover, length of hospitalization was significantly lower in the EVH group than in the OVH group.

Previous studies have reported lower rates of leg infections and better cosmetic results with the use of the endoscopic devices [2–6, 9]. Ad et al. [10] reported that postoperative morbidity rates, the incidence of myocardial infarction, and mortality rates associated with the endoscopic technique were comparable with those associated with the open technique. In our study, the incidence of lower extremity wound lymphorrhea was significantly lesser in the EVH group than in the OVH group (Table 3), although no significant intergroup difference was observed in lower extremity wound infection. Moreover, patient’s satisfaction with regard to wound cosmesis was higher in the EVH group.

Some studies have reported that EVH is associated with delayed vein graft failure [3, 6, 11]. Lopes et al. [3] reported that patients who underwent EVH showed higher rates of vein graft failure at 12 to 18 months (46.7%). Zenati et al. [11] reported that the SVG patency rate in the EVH group was lower than that in the OVH group (74.5% vs. 85.2%) with a 1-year follow-up. Although we did not investigate long-term outcomes in the present study, no significant differences were observed in the short-term results (Table 3).

The lower SVG patency rates observed in the EVH group could be attributed to the following technical issues [2, 11, 12]: the bipolar electrocautery can cause thermal injury to the vessel wall, which can affect graft quality by compromising endothelial cell viability, leading to platelet aggregation and thrombosis. Furthermore, manipulation of rigid devices during EVH may cause direct mechanical injury to the SVG.

We introduced a few technical modifications to the EVH procedure at our hospital. These particularly involve the back-approach technique using a C-ring (Fig. 1). We observed that patients who underwent this innovative procedure did not develop vessel wall injury caused by bipolar electrocautery scissors, which could be attributed to the fact that in this technique, the C-ring pushes the vein anterior to the side branches to avoid burn injuries to the main vein. However, the cutting edge of the bipolar electrocautery scissors may occasionally cause burn injuries to the vein walls during division of the relatively wide side branches of the vein. Therefore, we insert the C-ring posterior to the branch and tilt the C-ring to the branch gently. The branch is thereby stretched, and it is easier to cut the target branch using a bipolar electrocautery. The C-ring acts as a protective shield for the saphenous vein against the bipolar electrocautery. In this position, the back-approach technique, using a C-ring, can create a sufficient distance between the vein and the electrocautery blade to successfully cut the side branches. Notably, the C-ring directly protects the vein from the cutting edge of the bipolar electrocautery scissors and enables safe and easy division of the side branches.

However, the learning curve of EVH is a significant limitation of this approach. Initially, we observed a steep learning curve for EVH (operative time 40–50 min, 15 grafts); however, the curve flattened after we performed 20 graft procedures. Using the EVH technique, experienced surgeons could successfully harvest a SVG within approximately 20 min (data not shown). Therefore, compared with OVH, EVH prolongs the harvesting time.

As per our hospital policy, patients scheduled to undergo cardiac surgery are admitted 3 days preoperatively and undergo rehabilitation (minimum load: sitting on the edge of the bed; maximum load: 500-m walk + 2-step stairs exercise). Therefore, the length of hospitalization is comparatively longer at our hospital.

In this study, we could not confirm whether EVH and use of back-approach technique using a C-ring affect the long-term SVG patency rates and outcomes. However, we observed that this vein harvesting technique is useful, and our investigation is ongoing. A study performed by van Diepen et al. [13] reported no difference in the per-patient incidence of vein graft failure or per-graft incidence of vein graft failure between the OVH group and the EVH group at 12 to 18 months. Moreover, no intergroup difference was observed in the clinical outcomes at 5 years. Recent randomized trials did not observe a significant intergroup difference in the risk of major adverse cardiac events [14]. However, further randomized clinical trials are required to definitively establish the safety and effectiveness of EVH.

Limitations

A retrospective, small-scale single-center study design is a limitation of this study. Further prospective studies that include a large number of patients are warranted to gain a deeper understanding of this subject.

Conclusions

Compared with OVH, EVH using the back-approach technique was associated with satisfactory short-term results. EVH was associated with lower rates of leg wound complications and a shorter length of hospitalization. We propose that modifications, such as the use of the back-approach technique using a C-ring, might be effective for EVH during CABG.

Funding

There is no funding for this article.

Compliance with ethical standards

Informed consent

A written informed consent was obtained from all of the patients.

Conflict of interest

The authors declare that they have no conflict of interest.

Ethics committee approval

This retrospective study was approved by the institutional review board of Soka Municipal Hospital.

Human and animal rights statement

The procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) in our study.