Key words : Continuous suture method, Hepatic artery stenosis, Hepatic artery thrombosis, Liver transplant, Simple suture method

Introduction

Liver transplant surgery is among the most effective treatment methods in severe chronic liver failure patients and other liver disorders, including primary liver neoplasms, severe acute liver failure, and specific metabolic diseases.^1,2 The operation technique has been modified multiple times since the first liver transplant surgery by the American surgeon Thomas Starzl in 1963. As a result, the 1-year survival rate has reached 87% in patients who receive liver transplant.^3,4 There are multiple complications in patients with liver transplant, including early and late hepatic artery thrombosis (HAT) and hepatic artery stenosis (HAS) as the most prevalent complications.^5-7

Among various methods of liver transplant, the conventional method consists of 4 critical anastomoses: (1) suprahepatic caval vein anastomosis, (2) infrahepatic caval anastomosis, (3) portal vein anastomosis, and (4) hepatic artery anastomosis (it is notable that hepatic artery anastomosis is more complicated vs the other 3 anastomoses, due to arterial nature of the vessel wall).^8,9 End-to-end anastomosis is performed on the hepatic artery between the 2 arteries of the donor and recipient, by either the simple separate suture technique or the continuous suture technique. The choice of suture method in pediatric patients is well-elucidated due to the known prevalence of growth-related postoperative strictures and other complications among different suture types.¹⁰ However, sufficient studies for different suture types in adult patients are lacking. Only 3 types of sutures have been suggested for adult patients, which are (1) simple separate sutures, (2) continuous sutures, and (3) a com-bination of anterior separate sutures and posterior continuous sutures.¹¹ Our study aimed to evaluate the incidence of vascular complications and mortality in patients who have undergone transplant in which the simple separate suture technique (ie, interrupted sutures) was used versus patients who have undergone transplant in which the continuous suture technique was used.

Materials and Methods

This single-center prospective study investigated patients who had undergone deceased donor liver transplant surgery from January 2017 to December 2018 at the Imam Khomeini Hospital Complex, Tehran, Iran. The exclusion criteria were patients who died during the surgical procedure and patients with incomplete medical records. Patient demog-raphics were recorded, including age, sex, past medical history of liver disease, tobacco use, and comorbidities. The study was approved by the research center review board (ethics code: IR.TUMS.MEDICINE.REC.1398.259). All procedures were performed under the local committee’s ethical standards and the revised standards version of the Helsinki Declaration.

The study consisted of 2 groups of patients: those whose transplant was performed with continuous sutures (CS group) and those whose transplant was performed with simple separate sutures (ie, interrupted sutures) (SS group). The hepatic artery was the only anastomosis evaluated. All patients included in this study were recipients of liver transplants from deceased donors. Information about the date and the duration of the operation and the suture techniques was acquired from the patients’ electronic medical records.

The acquired follow-up data included any complications (eg, HAT, HAS, or anastomosis leakage) along with the exact date of the event and the possible need for retransplant. The follow-up procedure was conducted according to previously established guidelines and modalities.^12-14 The postoperative 2-year survival rates of the patients were also recorded.

For statistical analyses, we used SPSS software (version 22; IBM). Mean values (with SD) were used to demonstrate the quantitative variables, whereas the qualitative variables were assessed according to prevalence. Descriptive tests were used to determine demographic data and tobacco use. In contrast, data about the suture techniques were matched between 2 groups based on propensity scores of age, sex, cause of liver failure, and comorbidities. Afterward, the survival data were evaluated according to the chi-square goodness-of-fit test. After assessment of the normal distribution of the duration of surgery in the 2 groups by the Kolmogorov-Smirnov test, t test was used to compare the duration of surgery between the 2 groups.

Results

We included 194 patients in this study; mean age was 47.57 years (SD 12.83 years). The youngest and the oldest patient were 3 and 65 years old, respectively. This study included 125 male patients (64.4%) and 69 female patients. Patient comorbidities (Table 1) consisted of diabetes type 2 in 25 patients (13.4%), hypertension in 9 patients (4.9%), and inflammatory bowel disease in 6 patients (3.2%), among other less prevalent diseases. There were 139 patients (74.7%) who lacked underlying conditions other than liver dysfunction. Eight patients who underwent first-time transplants and retransplant in our hospital are only included once in Table 1. Hence, the total number of patients listed in Table 1 is 186. As shown in Table 1, the most common causes of liver failure were cryptogenic liver failure (n = 41; 21.1%), autoimmune liver failure (n = 33; 17.0%), hepatitis B virus (n = 21; 10,8%), and hepatitis C virus (n = 20; 10.3%). There were 186 patients (95.9%) who had received a first-time transplant, whereas 8 patients (4.1%) had received retransplant surgery. The mean duration of operation was 279.39 minutes (SD 57.²¹ minutes). The mortality data showed that 43 patients (22.2%) died within 2 years after transplant, and their mean postoperative survival time was 179.81 days (SD 356.68 days).

There were 178 (91.8%) patients in the CS group and 16 (8.2%) patients in the SS group. Due to this large difference in the number of patients between the 2 groups, the patients were matched between groups by propensity scores based on age, sex, etiology of liver disease, and comorbidities. No patient showed signs of HAT or HAS in either group. We used the Kolmogorov-Smirnov test to demonstrate that the duration of surgery recorded for the patients had a normal distribution (P = .74). Afterward, we used the t test to compare the duration of the surgeries, which showed no significant difference between the 2 groups (P = .654) (Figure 1). With regard to 2-year survival rate results, the SS group showed significantly higher mortality rates versus the CS group (P = .043).

Discussion

Hepatic artery anastomosis is one of the primary anastomoses performed in liver transplant. This procedure can be further complicated in pediatric patients with shorter-length hepatic arteries from the donor, the size difference between donor and recipient arteries, and patients with lower weight and smaller stature.^15,16 Hence, any further advance in suture technique is aimed to ease the procedure of operation and decrease the rate of complications or retransplant. Although our findings showed a higher mortality rate in the SS group versus the CS group, this phenomenon is probably a result of other concomitant etiologies in these patients.

In a study by Tannuri and colleagues, the SS technique was compared with the CS approach in 82 pediatric patients with equal group count and showed no significant difference in rates of HAT or HAS between the 2 groups.¹⁷ Tzeng and colleagues reported similar outcomes with 2 equal nonran-domized CS and SS groups (each group included 20 patients) in whom no HAT was observed.¹⁸ Our results are in line with the 2 studies mentioned. However, the only similar report with a different outcome in the literature was from Coelho and colleagues, which showed higher rates of HAT were associated with the CS technique.¹⁹ Interestingly, that study had 200 patients, which is a much larger group than the other studies we have mentioned.

Some new techniques for anastomosis sutures with promising results are worth mentioning. Okochi and colleagues observed that the posterior wall of the hepatic artery is among the most complex regions for suturing. They proposed a combination of continuous sutures in the rear wall followed by simple separate sutures in other sites of hepatic artery anastomosis.^11,20 This technique, initially applied on rats in the year 2000, was applied on 13 patients from 2006 to 2010, with no evidence of HAT during the follow-ups. Another study, by Haberal and colleagues, on 54 living donor transplant recipients, showed that proper anastomosis could be achieved by spatulation of the anterior and posterior walls of the hepatic arteries.²¹ This finding is notable because it could simplify the operation on the arteries, regardless of size. Boyvat and colleagues proposed that early diagnosis of HAS could facilitate feasibility of endovascular stent approaches to manage this emergency complication.^22,23 Hence, watchful follow-up for both methods may further improve the postoperative prognosis of liver transplant patients.

In a previous study, Hamilton and O’Brien showed that the CS technique facilitates shorter operation time because of the fewer number of knots required.²⁴ It has been documented that the increase in the duration of an operation is associated with higher risk of postoperative complications and increased morbidity and mortality.²⁵ Nonetheless, the duration of the procedure did not differ significantly between the 2 groups in our study. Hence, our study suggests that the SS method and the CS method have similar rates of arterial thrombosis, arterial stricture, and other complications in the case of hepatic artery anastomosis.

The most notable limitation of our study is the asymmetry in the number of patients in the 2 groups, because the CS approach is more frequently perfor-med versus the SS technique. Moreover, there are 3 surgeons performing transplants at the Imam Khomeini Hospital Complex, and this variable may cause minor differences in patient outcomes.

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