End-to-Side Versus End-to-End Venous Anastomosis Using Couplers in Mandibular Reconstruction: A Comparative Study

Abstract

Purpose

This study compares the advantages of end-to-side technique over end-to-end technique for venous anastomosis using couplers.

Methods

Patients were divided into group I and group II based on end-to-side and end-to-end techniques, respectively. Intraoperative anastomotic time, flap ischemic time, and postoperatively flap vitality were the parameters evaluated.

Results

Thirty-eight patients were randomly allocated to two groups with 19 patients in each group. The mean anastomotic time with standard deviation in group I was 391.84 ± 49.052 s and in group II was 354.47 ± 46.365 s with p value 0.021. The mean flap ischemic time with standard deviation in group I was 180.68 ± 35.773 min and in group II was 161.21 ± 32.418 min with p value 0.087. All the flaps in group I were vital, whereas 78.9% of flap vitality was observed in group II with p value 0.105.

Conclusion

Based on this study, end-to-side venous anastomosis using couplers is a better technique over end-to-end venous anastomosis.

Introduction

Microvascular free flap transfer has become the first choice for reconstruction of defects due to its promising results. Though the success of reconstruction depends on multiple factors, maintaining a patent microvascular anastomosis is of paramount importance [1, 2]. Apart from the arterial supply, restoration of microcirculation to the free flap is achieved with adequate venous drainage. The adequacy of drainage is not only relying on the volume of the flap and the corresponding vessels, but also the quantity of the venous blood which has to be drained from the flap. The vessel diameter discrepancy has an impact on the effective venous drainage which in turn governs the choice of the anastomotic technique [3].

Conventionally, the veins are anastomosed with end-to-end technique using microsutures. when the defects with compromised recipient bed or host need to be addressed, either dual venous anastomosis or end-to-side anastomosis is performed. Microsuturing the vein end with the side of the large volume vessel is practiced for many decades. Apart from prolonged anastomotic time and ischemic time with microsuturing, the suture needle readily insults the media and intimal layer which may induce vasospasm [4]. The non-suturing method of anastomosis such as couplers had made their impact to overcome the disadvantages associated with microsuturing [5]. The aim of this study is to compare the advantages of end-to-side technique over end-to-end technique for venous anastomosis in reconstructive surgery.

Materials and Methods

Patients who reported to the Department of Oral and Maxillofacial Surgery between 2014 and 2017 with a spectrum of pathological conditions of the mandible requiring resection followed by reconstruction of the osseous defect were included in this study. Patients with systemic co-morbidities, uncontrolled diabetes mellitus, peripheral vascular disease, and altered anatomy of the donor sites were excluded. Free fibular flap with skin paddle was chosen for reconstruction of the defect. The venous anastomosis was carried out with microvascular coupler device and system—2.0 mm, 2.5 mm, and 3.0 mm (GEM-Synovis Micro Companies Alliance, Inc., Birmingham, USA). The study was endorsed by the Institutional Review Board Committee.

Thirty-eight patients were included in the study and were categorized into two groups. Patients with end-to-side venous anastomosis were allocated to group I (19) and group II (19) including patients with end-to-end technique of venous anastomosis. (Fig. 1) Intraoperative anastomotic time, flap ischemic time, and postoperatively flap vitality were the parameters evaluated for both the groups. All the arterial anastomoses were carried out by microsuturing. All surgeries were performed by the same surgeon.

Fig. 1.

Schematic representation methodology implemented in this study

Anastomotic time was calculated from the time of clamping the vessels for the preparation of vessels to the time of releasing the clamps after the completion of the anastomosis.

Ischemic time was the time between the interruption and reestablishment of blood supply to the flap at the recipient site after anastomosis.

Postoperatively, the flap vitality was checked with the pinprick test of the skin paddle.

Surgical Procedure

End-to-Side Anastomosis

With the measuring gauze, the diameter of the flap vein (donor's vessel) was measured, and the appropriate coupler was selected. The internal jugular vein (IJV) was clamped with bulldog clamps. Venotomy was performed in a circular pattern on the lateral wall of the IJV according to the diameter of the donor's vessel. The terminal of the donor's vessel and prepared end of the recipient's vessel were gradually drawn through the rings. The vessel lumen was checked thoroughly and irrigated to flush out microdebris. The instrument was rotated clockwise until the terminal approximation of the coupler was attained. The tight locking of the pins with their corresponding hole in its counterpart with a friction fit was achieved after crimping the two wings together with a hemostat. The device was vented, and parameters were assessed (Fig. 2).

Fig. 2.

End-to-side anastomosis with IJV performed using microvascular couplers

End-to-End Anastomosis

With the measuring gauze, the diameter of both donor and recipient vessels was assessed and coupler was chosen. The coupler was loaded onto the application device, and the terminals of the vessel were gradually drawn through the rings. The vessel lumen was checked thoroughly and irrigated to flush out microdebris. The anastomotic instrument was rotated clockwise until the terminal approximation of the coupler was attained. The tight locking of the pins with their corresponding hole in its counterpart with a friction fit was achieved after crimping the two wings together with a hemostat. The device was vented, and parameters were assessed (Fig. 3).

Fig. 3.

End-to-end anastomosis performed using microvascular couplers

Results

Thirty-eight patients (22 male and 16 female) with age ranging between 15 and 61 years (mean age is 36 years) had taken part in the study. The diagnosis and number of particular conditions were ameloblastoma (18), odontogenic keratocyst (8), osteoradionecrosis (2), aneurysmal bone cyst (2), secondary deformity (4), calcifying epithelial odontogenic tumor (3), and 1 patient with ossifying fibroma. Independent sample T test was executed to compare the mean anastomotic time and mean flap ischemic time among the two groups. The mean anastomotic time in group I with a standard deviation was 391.84 ± 49.052 s and in group II was 354.47 ± 46.365 s with p value 0.021 and t value of 2.413 (Table 1) (Fig. 3). The mean flap ischemic time with standard deviation in group I was 180.68 ± 35.773 min and in group II was 161.21 ± 32.418 min with p value 0.087 and t value of 1.758 (Table 2). All the flaps in group I (19 patients) were vital with 100% vitality, whereas, in group II, out of 19 patients, 15 patients have obtained good functional and aesthetic outcomes. However, four patients resulted in flap loss: two cases on the third day, one on the fourth day, and one patient after one week, respectively. A Chi-square test was carried out to compare the flap vitality. 78.9% of flap vitality was observed in group II with p value 0.105 (Table 3). In the above four cases, contrast-enhanced ultrasonography was performed to assess the flap circulation. The cause for the flap failure was found to be venous congestion. Re-anastomosis of the donor vein was performed with IJV in end-to-side fashion. The flaps were further assessed which showed improvement in vitality.

Table 1.

Independent sample T test to compare the mean anastomotic time between groups

Variables	Group	N	Mean	Std. Dev	t value	P value
Anastomosis time (secs)	Group I	19	391.84	49.052	2.413	0.021
	Group II	19	354.47	46.365

Table 2.

Independent sample T test to compare the mean flap ischemic time between groups

Variables	Group	N	Mean	Std. Dev	t value	P value
Flap ischemic time (mins)	Group I	19	180.68	35.773	1.758	0.087
	Group II	19	161.21	32.418

Table 3.

Chi-square test to compare the flap vitality between groups

Variables	Group	n	Percentage of vitality (%)	P value
Flap vitality	Group I	19	100	0.105
	Group II	19	78.9

Discussion

Microvascular reconstruction being the reliable method of reconstruction, it requires intense training in performing an anastomosis. The survival of free flaps relies on the quality of circulation. Apart from flap perfusion by arterial circulation, adequate venous drainage is essential. Anastomosis performed with a larger vein provides adequate drainage further resulting in an improved surviving percentage of free flaps [6]. Venous coaptation is more challenging than the arterial anastomosis because the veins are low-pressure, thin-walled and are compromised readily by kinking, torsion, or external compression [7]. Zhang et al. stated that veins are susceptible to spontaneous congestion after anastomosis and the venous return of the flap gets jeopardized [8]. The vessel diameter discrepancy has a major influence on the choice of the anastomotic technique. Cakir et al. had described the size discrepancy as inequality of vessel (vein) diameters at a ratio of 1:1.5 or greater. this was observed most frequently during venous anastomosis [9]. Insignificant discrepancy in the vessel diameter was addressed by the mechanical expansion of the smaller vein followed by the end-to-end anastomosis [3]. Significant vessel diameter discrepancy was addressed by fish mouth incision of the smaller vessel followed by an end-to-side microsuturing anastomosis [10]. In the case of vessel size discrepancy, the end-to-side technique of venous anastomosis reduces the incidence of thrombus formation [11]. Lauritzen reported sleeve anastomosis in cases of vessel mismatch. The reported disadvantage of this technique with a donor, small-caliber downstream end to the recipient, large-caliber upstream end results in turbulence in blood flow resulting in thrombi formation [12].

Acland stated that end-to-side type of anastomosis overcomes problems related to vessel size discrepancy, allowing IJV venotomy of the exact size of the donor's vessel. The advantages related to such recipient vein are improved venous outflow due to the respiratory venous pump effect, the possibility to freely choose the anastomotic site along the entire length of the IJV, and the potential to perform even multiple anastomoses [13]. Godina [14] had described the advantages of end-to-end anastomosis such as (1) solving size discrepancies, (2) preserving the blood flow distally, (3) easy to plan and a large-caliber vessel can be available, (4) avoiding retraction and spasm in the supplying recipient vessel, and (5) reliable as the end-to-end anastomosis.

Microsuturing with 8–0,9–0 nylon has been the conventional and successful method for vascular anastomosis. Apart from the time involved, the vessel anatomy plays a key role in success as the suturing needle readily insults the medial and intimal layer which may induce vasospasm. Hence, the method of anastomosis which injures the deeper layer of the vessel during the process greatly inhibits the blood flow after anastomosis [4]. Thomson et al. described that microsuturing involves the endothelial layer which inevitably leads to thrombus formation [15]. These thrombi induce turbulence which results in an increased number of collisions of blood cells with adjacent areas of stasis, thus promoting thrombus formation and complete vascular occlusion [16].

To overcome the aforesaid, over time several non-suturing anastomotic techniques were advocated. Microvascular couplers being one of the non-suturing anastomotic techniques had gained the credibility and reliable method of venous anastomosis. Murugan et al. had stated that, when the flap ischemic time reduces, the incidence of success also increases considerably. Insult to the deeper anatomical layers and resultant spasm of the vessel also influences the flap survival [5]. By using the mechanical anastomotic devices like microvascular couplers, anastomoses with end-to-end and end-to-side methods are made easy. The use of couplers aids in decreasing anastomosis time, flap ischemic time, and microvascular complications [17, 18].

The coupler device system is available with inner diameters ranging from 1.0 to 3.0 mm at 0.5-mm intervals and can be applied successfully to vessels in the same range of sizes. The most common being used is 2.0 mm and 3.0 mm. The diameter of the coupler has no correlation with the failure of the flap [8]. Microvascular couplers are the most commonly used non-suture anastomotic system. The device can be used without fear of foreign body reaction or long-term sequelae. In addition, mechanically coupled anastomosis shows a 50% increase of burst strength 16 weeks after surgery compared with sutured vessels [19].

Nishimoto et al. stated that the scaffold effect of the coupler rings, which prevents the vessel wall from collapsing [20]. DeLacure et al. published a case series of 37 end-to-side venous anastomoses, of which 33 (89%) were completed. Four anastomoses were conventional sutures because of the thick or friable vessel wall. They postulated that a thick and friable vessel wall as a result of previous treatment is a relative contraindication to the use of a coupler device. Flap survival in this series was 100%, concluding that end-to-side venous anastomosis with a microvascular anastomotic coupler device is well suited when carefully and selectively used by experienced microvascular surgeons [17].

The challenge with the application of couplers is anastomosing the vessels with mismatched calibers. In such conditions, the type of venous anastomosis has been done in end-to-side fashion with good results [21]. Studies have compared dual venous anastomosis over single anastomosis in head and neck reconstruction. It shows that failure rate using dual venous anastomosis is about 4% (range, 0–10%) compared to that of single vein anastomosis which is about 7% (range, 3–12.5%), respectively [22–24].

In this study, by performing end-to-end anastomosis, there was a significant decrease in anastomotic time which in turn reduced the ischemic time but the vitality of the flap was found to be better with end-to-side anastomosis. There was no tearing of vessels or any thrombus formation in both the groups. There was immediate refilling of the vessels without any leakage in all the patients. The perfusion was good even in the follow-up period. There was no flap failure in all the patients who underwent anastomosis of a vein in an end-to-side manner. However, in group II, there were two of the 19 patients, where the flap failed by performing the end-to-end anastomosis.

Conclusion

The end-to-side technique of venous anastomosis with a larger recipient vessel, i.e., IJV using coupler device, has advantages such as decreased anastomotic time, flap ischemic time, and improved flap survivability over the end-to-end technique of venous anastomosis. The double venous anastomosis is another potential technique for adequate venous drainage.

Authors Contribution

MSM contributed to conceptualization and performed the procedure, review, and supervision. SKM performed assistance during the procedure, documented the data, and drafted the manuscript.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Compliance with Ethical Standards

Conflicts of interest

None.

Ethical Approval

Ethical approval was obtained from the Institutional Review Board committee.