Long-term effects of Kasai portoenterostomy for biliary atresia

The prospective study enrolled 144 patients after surgical treatment of biliary atresia in early infancy. We analyze the immediate effectiveness of the surgery and the age-related structure of complications in the up to 16-year follow-up. The immediate 2-year survival rate after the surgery constituted 49.5%. At the time of this writing, 17 of the patients have celebrated their 10 th birthdays with good quality of life and no indications for LT. The obtained results underscore the critical importance of surgical correction of BA by Kasai surgery during the first 60 days of life and subsequent dynamic follow-up of the patients for the purpose of the early detection and timely correction of possible complications.


Introduction
Till the mid 20th century biliary atresia (BA) was lethal [1,2]. Surgical correction of this defect by portoenterostomy was introduced in 1952 by Prof. Morio Kasai. The operation includes resection of fibrotic lesions in the portal area and re-establishment of the physical connection of the liver with the intestine by a Roux loop anastomosis resulting in restoration of the bile flow to the intestine [3]. This operation is considered as a maintenance treatment for the majority of BA cases. It prolongs the native liver survival in preparation for the liver transplantation (LT). Current estimations of 5-year survival rates for BA patients with native 1. Evaluation of functional condition of the liver (cholestatic syndrome manifestations, increased transaminase levels, and indicators of synthetic activity of the liver) with relation to age; 2. Analysis of immediate or delayed complications (postoperative complications, bacterial cholangitis, bile ducts dilatation, portal hypertension, hepatopulmonary syndrome) with relation to age; 3. Survival study.
Cholangitis was diagnosed on the basis of febrile fever symptoms, elevated serum levels for the markers of systemic inflammation (C-reactive protein, procalcitonin), alterations in ESR, WBC counts and WBC differential, in combination with varying degree of clinical and biochemical manifestations of cholestatic syndrome, increased transaminases, and reduced synthetic function of the liver.
Portal hypertension was determined on the basis of impaired blood flow in the portal system (umbilical vein recanalization, ascites, enlarged spleen, and the altered volume rate of portal blood flow) as revealed by Doppler ultrasound examination, esophageal varices, and hematological indicators of hypersplenism (thrombocytopenia, anemia, leukopenia).
The follow-up duration varied from 6 months to 16 years.
The data were processed in StatSoftStatistica 10 (StatSoft Inc., Tulsa, OK, USA) and Microsoft Excel 2016 software. Numerical variables were described by mean and standard deviation values (mean ± SD). Categorical variables were described by absolute numbers and frequencies of the events. Univariate comparisons for two dependent groups were made by nonparametric Wilcoxon test. Bilateral Fisher's exact test was applied for the comparison of frequencies between the groups. The survival was described by Kaplan-Meier curves. The differences were considered statistically significant at p < 0.05.
were operated at younger age (< 60 days of life) and 36 infants (25%) were operated at > 90 days of life.
During the postoperative in-patient care, serious complications were developed by 7 patients (4.9%). One patient had duodenal perforation on day 4 post-operation (p/o), and two patients had colon perforations on days 3 and 7 p/o; these patients were re-operated for the management. One patient had adhesive intestinal obstruction treated surgically on day 15 p/o. Gastrointestinal bleedings in three other patients were treated conservatively. One patient died of colon perforation on day 12 p/o.
The effectiveness of surgical intervention (as assessed by coloration of stools, jaundice reduction, and a decrease in bilirubin levels in the early postoperative period) constituted 89.5% (128 patients). For 16 patients (11.1%) the operation was ineffective.
In the patients with ineffective surgery (n = 16), the stools remained acholic, the jaundice persisted, the biochemical markers of cholestasis and transaminase increased, and the indicators of synthetic function of the liver decreased. The situation eventually led to biliary cirrhosis with lethal outcomes for 2 patients (1.7%) at the age of 5 and 7 months. Twelve patients with ineffective Kasai surgery received liver transplants at the age of 7.8±2.5 months.
In 128 patients who benefited from the surgery (89.5% of the total sample), the coloration of stools occurred on day 4.36±4.32 p/o. Although for the majority of patients in this group the colored stools were primarily observed on days 3-4 p/o, in few cases the coloration occurred on day 1 p/o. In 2 patients, the coloration primarily occurred on days 30 and 34 p/o. During the postoperative in-patient care, the jaundice was attenuated in 90 patients and totally suppressed in 28 patients.
Furthermore, in 122 patients (95.3% of 128 patients who benefited from the surgery) bilirubin levels were reduced from 172.62±63.7 to 93.6±63.2 µmol/L, while in 6 patients both total and direct bilirubin levels were reduced to normal values (Table 1). A rapid reduction in GGT activity to normal levels was observed in 16 patients, while the majority experienced an increase in the GGT activity during postoperative period, despite the reduction in bilirubin levels, coloration of stools, and mitigation of jaundice. These changes were statistically significant ( Table 1). A transient increase in the activity of transaminases observed in the majority of patients (92.5%) during the early postoperative period (Table 1) may be considered as a physiological response to inhalational anesthetics, somnoleptics, myorelaxants, and antibacterials (as the liver is basically involved in their metabolization) and is definitely not a poor prognostic factor. No significant changes in the plasma cholesterol levels of the patients were observed during the postoperative in-patient care (Table 1).   Table 2.
By the age of 1 year, total bilirubin was reduced to normal levels in 25 patients with effective Kasai surgery (constituting 11.8+2.3 µmol/L). In 73 patients, bilirubin was still elevated (98.4+33.6 µmol/L) but significantly and stably reduced as compared with the initial levels before the surgery. By the age of 2-3 years, bilirubin levels were reduced to normal values in all patients with effective Kasai procedure (Table 2). By the age of 1 year, the activity of GGT was reduced to normal values in 22 patients. In 76 patients, it was still elevated but reduced significantly as compared with the initial level. By the age of 3 years, 86% of the patients had normal GGT levels. Several cases of persistence of the elevated GGT levels should be noted (up to 412.3 U/mL, Table 2), although such patients had normal levels of bilirubin and other cholestasis markers, and showed no indications for LT.  Table 2). By the age of 4 years, 65% of the patients had normal levels of transaminase activity. However, the moderate elevation of ALT/AST activity persisted in 14% of the patients for at least 3-5 years after the surgery.
Thus, the majority of BA patients with effective Kasai surgery showed normal bilirubin levels by the age of 1 year, while the reduction in the activity of GGT, ALT and AST took much longer, and the elevated blood plasma levels for these enzymes typically persisted (for > 5 years in some patients).

Complications
The age-related structure of complications is shown in Figure 1.
Bacterial cholangitides and portal hypertension occurred most typically. Cystic dilatation of intrahepatic bile ducts was less common. One patient developed hepatopulmonary syndrome used as an indication for LT at the age of 3 years.

Cholangitides
During the 1 st year after surgery, 102 of 143 patients (71%), regardless of the effectiveness of the surgical intervention, had at least a single episode of cholangitis which required the in-patient treatment with intravenous administration of antibacterials ( Figure 1). Seven patients with recurrent cholangitides were re-operated for the antireflux valve insertion, which was effective.
In 19 patients with effective Kasai surgery, the recurrent cholangitides promoted the onset of liver cirrhosis, which served as an indication for LT performed at the age of 9-14 months.
During the 2 nd year of life, 54 of 98 patients (55%) had episode(s) of cholangitis requiring the in-patient antibacterial therapy (Figure 1). Two of the patients underwent the antireflux valve insertion at the age of 18 and 19 months. In 24 patients, cholangitis led to biliary cirrhosis; these patients received liver transplants at the age of 18-28 months.
During the 3 rd year of life, acute cholangitis was diagnosed in 20 patients (33%, Figure 1).
Three of those developed weak signs of systemic inflammatory reaction, but acholic stools were observed in none of the cases. The episodes were successfully resolved by oral administration of antibacterials on the out-patient basis.
During the 4 th and 5 th years of life, cholangitis was diagnosed in 11 patients (22%, Figure 1).
For the age groups of 5-10 and > 10 years, the occurrence constituted 15% and 16%, respectively. In the latter group, only 2 patients had single episodes of hepatocellular dysfunction with portal hypertension at the age of 12 and 14 years (despite the ongoing observation and maintenance therapy), which served as indications for LT. During the 2 nd year of life, 43 patients (44%, Figure 1) manifested the signs of PH including recanalized umbilical vein (rUV, 5 cases, 11.6% of PH cases), ascites (4 cases, 9.3%), and/or EV (14 cases, 32.6%, including 2 cases of EV grade I, 7 cases of EV grade II, and 1 case of EV grade III). Three patients had EV bleedings and received sclerotherapy. Hypersplenism was observed in 18 cases (41.9% of PH cases), with the related splenic thrombocytopenia in 14 cases and a combination of thrombocytopenia and anemia in 5 cases.

Portal hypertension
Two patients, 1.5 and 2.5 year old, diagnosed with EV grade III-IV with high risks of bleeding, received a small-diameter splenorenal shunt, which ensured partial drainage of the blood from portal circulation into the vena cava inferior. This intervention mitigated the severity of EV to grade I-II.
Three EV patients received sclerotherapy. Two patients had esophageal bleedings, the conservative treatment of which was successful. The signs of hypersplenism were observed in 7 cases (29.2%), the related splenic thrombocytopenia was identified in 8 cases (33.3%) and splenic thrombocytopenia combined with anemia was identified in 2 cases of PH (8.3%).
During the 4 th and 5 th years of life, 20 patients (44%, Figure 1) manifested the signs of PH including rUV (11 cases, 55% of PH cases), EV (16 cases, 80%, including 8 cases of EV grade I, 5 cases of EV grade II, and 3 cases of EV grade III) and/or thrombocytopenia (9 cases, 45%).
Among the 5-10 year olds, 22 patients (70%, Figure 1)  At the age of > 10 years, 13 of 17 patients (76%, Figure 1) manifested signs of PH including rUV in 12 cases (92.3% of PH cases), EV in 13 cases (100%, including EV grade I in 5 cases, EV grade II in 5 cases, and EV grade III in 3 cases), hypersplenism with thrombocytopenia in 13 cases (100%), and hypersplenism with thrombocytopenia combined with anemia in 10 cases (76.9%). Two of the patients had EV bleedings, and one patient received sclerotherapy. patients aged > 10 years (17.6%). It should be noted that, by contrast with biliary cirrhosis, none of the observed iHBD dilatations interfered with synthetic function of the liver, and this condition can be generally interpreted as a consequence of the partial biliary obstruction prior to the portoenterosromy and in association with it.

Figure 2. Survival with native liver (non-LT subgroup) after Kasai surgery.
For the native liver (non-LT) subgroup stratified by the age at Kasai surgery, survival rates for the patients operated at the age under 60 days were higher. Of those differences, however, only the difference in 2-year survival rates was significant (р < 0.05, Figure 3). It should be noted that survival rates for the < 1 year-olds showed no correlation with the age at Kasai surgery ( Figure 3).  The observed correlation of the native liver survival rates with the age at surgery is consistent with the literary data on this subject [11,13,16,19]. Portal hypertension (PH) of diverse pathophysiology (from the moderate splenomegaly and umbilical vein recanalization, which minimally affected the life quality, to the ascites and severe esophageal varices) was manifested by 47% of the patients during their first year after the surgery. Later on, the occurrence of PH increased, reaching 76% after the age of 10 years. The primary cause of PH is hepatic fibrosis, which develops before the operation and subsequently becomes aggravated by recurrent cholangitides. According to the reported evidence, portal hypertension in the follow-up of Kasai surgery occurs in 37-70% of the patients Error! Reference source not found.Error! Reference source not found.. Importantly, for the patients with effective Kasai surgery, even the clinically evident PH was not considered as an indication for the emergency liver transplantation, as the varices were subject to scheduled surgical correction, thrombocytopenia was not accompanied by hemorrhages, and no indications for blood transfusion were encountered. Apparently, PH is a primary consequence of the fibrotic alteration of hepatic tissues within the portal area. Therefore, PH episodes are inherent for BA, and can only be mitigated (not completely resolved) by a successful Kasai surgery. Strictly speaking, PH should be considered as an echo of deteriorating changes that would rapidly progress in the absence of timely surgical intervention (and this point is consistent with our observations for the cases of ineffective surgery). However, a detailed discussion of this issue is beyond the scope of this study.

Conclusion
The results of this study support the view of Kasai surgery as a crucial maintenance measure for BA patients, which is also the essential precondition of native liver survival. The immediate 2-year survival rate after the surgery constituted 49.5%. At the time of this writing, 17 of the patients have celebrated their 10 th birthdays with good quality of life and no indications for LT.
For less successful outcomes, the Kasai procedure still allows to delay LT for at least few months, considering that LT effectiveness largely depends on the age and satisfactory physiological condition of the patient.