Dysphagia-free Period Research Articles

Long-term outcomes of refractory esophageal strictures after endoscopic submucosal dissection of superficial esophageal neoplasms

BackgroundMany studies have focused on prophylactic therapy for post-endoscopic submucosal dissection (ESD) of esophageal strictures. However, various strategies cannot prevent the occurrence of postoperative strictures after extensive ESD. Postoperative strictures often inevitably occur, and endoscopic dilation is still a temporarily effective therapy.MethodsThis study included patients with post-ESD refractory esophageal strictures (RESs) from January 2014 to November 2019. Clinical effectiveness was assessed using univariate analysis and multivariate logistic regression. Hierarchical linear models were used to identify factors that predicted the dysphagia-free period.ResultsA total of 50 patients fulfilled the inclusion criteria and entered the study. Twenty-seven (54%) patients had a history of prophylactic oral steroid therapy. Forty-six patients (92%) underwent ≥ 75% circumferential resection, including 32 (64%) cases involving entire circumferential ESD. The mean dysphagia-free period of 50 patients was 2.9 months (95% CI 2.3–3.5). The dysphagia-free period had a linear growth trend over time, increasing by 6.9 days per endoscopic therapy, and the estimated last dysphagia-free period was 85.9 days. Old and female patients had shorter dysphagia-free periods compared with young and male patients. Endoscopic therapy success was achieved in 30 (60%) patients. Multivariate analysis revealed that circumferential lesions (OR 6.106, 95% CI 1.013–36.785, P = 0.048) were significant predictive factors for poor clinical outcome.ConclusionEndoscopic dilation seemed effective in patients with post-ESD RESs by increasing the dysphagia-free period. After approximately 10 continuous dilations, 60% of patients achieved endoscopic success, and the remission rate of obstruction was increased. Prophylactic oral steroid therapy could reduce the occurrence of RESs. However, once a RES had occurred, prophylactic steroid therapy could not reduce the frequency of dilations or change the long-term outcomes.Trial registration: This study was prospectively registered and approved by the Ethics Committee of West China Hospital of Sichuan University (IRB number: ChiCTR-ONN-17012382) on 2015.

Appropriate duration of endoscopic dilation for postoperative benign esophageal strictures.

Benign esophageal strictures are a frequent complication after esophageal surgery or extensive endoscopic submucosal dissection. Endoscopic dilation is the preferred treatment in clinical practice. However, the allocation of time for each dilation is unclear. The aim of this study was to evaluate the appropriate duration of endoscopic dilation for benign esophageal strictures after esophageal surgery or endoscopic submucosal dissection. Patients with benign esophageal strictures after esophageal surgery or endoscopic submucosal dissection between July 2010 and July 2018 were retrospectively included in this study. According to the dilation time (1, 3, 5min), patients were divided into three groups. The clinical effects and adverse events were compared among the three groups. Altogether, 57 patients, including 21 in the 1-min group, 18 in the 3-min group and 18 in the 5-min group, were included. All patients underwent endoscopic treatment successfully. The stricture recurrence rate was 76.19% in the 1-min group, 55.56% in the 3-min group and 61.11% in the 5-min group. The median overall dysphagia-free period was 2.60 (range, 0.80-12.00) months in the 1-min group, 6.60 (range, 1.80-12.00) months in the 3-min group and 6.25 (range, 2.40-12.00) months in the 5-min group (P < 0.05). For patients who developed stricture recurrence, the mean dysphagia-free periods were 2.26 ± 1.27months, 4.00 ± 1.76months and 4.23 ± 1.63months, respectively (P < 0.05). The dysphagia-free periods were comparable between the 3- and 5-min groups and were longer than those in the 1-min group. Muscle layer damage occurred in two patients (11.11%) in the 5-min group and in no patients in the other two groups. Three minutes was considered a safe and effective dilation duration for benign esophageal strictures after esophageal surgery or endoscopic submucosal dissection.

Predictors of successful endoscopic management of caustic esophageal strictures in children: When to stop the dilatations?

BackgroundCaustic esophageal strictures are mainly managed by endoscopic dilatations. Cases that do not respond to the dilatations eventually require an esophageal replacement. The aim of our study was to identify factors that could allow us to predict if the dilatations will be successful or not. MethodsWe retrospectively reviewed the chart of 100 patients with caustic esophageal injuries treated at our center between 2012 and 2019. Collected data included age, gender, type of caustic substance, duration of the dilatations, length and extent of the strictures, number and time interval between dilatations, presence of gastroesophageal reflux, occurrence of esophageal perforation, and outcome of the dilatation program. ResultsThe patient ages ranged from 1 to 8 years old. The overall success rate was 98.2% for patients with short strictures and 81.8% for patients with long strictures (>3 cm). A long stricture, a pharyngeal extension of the stricture, the occurrence of an esophageal perforation, and the presence of gastroesophageal reflux were strong predictors of the failure of the dilatation program. The median treatment time for the patients to achieve a cure was 5 months in cases of short strictures and 17 months in cases of long strictures. Within the subgroup of patients with long strictures, a dysphagia-free period within the first year of management of 8 weeks was associated with the success of the dilatation program. ConclusionA length of more than 3 cm, pharyngeal involvement, the occurrence of esophageal perforation, and the presence of gastroesophageal reflux are predictors of failure of dilatations for the management of caustic esophageal strictures. A dysphagia-free period of 8 weeks or more within the first year of dilatations is considered a predictor of success of dilatations in patients with long strictures. Level of EvidenceLevel II.

Intralesional Mitomycin C Injection in Management of Caustic Esophageal Stricture in Children

Abstract Background Corrosive ingestion is a devastating event that induces significant burdens on modern health systems worldwide. The management of resulting esophageal strictures is challenging where endoscopic dilatation is the first line of management with varying rate of success. Aim of the Work We aimed at this work to study the feasibility and safety of intralesional Mitomycin C injection in patients with caustic localized esophageal stricture. Patients and Methods This study has been conducted at Pediatric Surgery Department, Pediatric Hospital, Ain Shams University Hospitals on eight pediatric patients with caustic esophageal stricture with variable degrees of dysphagia. We evaluated the clinical improvement of the dysphagia, as well as the intra and postoperative complications of Mitomycin C injection. Results Eight patients with short caustic esophageal stricture were managed with intralesional Mitomycin C injection adjuvant to endoscopic dilatation. Seven patients were completely cured from dysphagia with at least 6 months dysphagia free period. No intraoperative complications were documented while there were two cases who reported GIT side effect postoperative in the form of colics and non-bilious vomiting that resolved by medical treatment. Conclusion Intralesional Mitomycin C injection could be a good adjuvant therapy with endoscopic dilatation for caustic esophageal stricture. However, long-term observations are mandatory on a large scale of patients.

The role of endoscopic dilation and stents in refractory benign esophageal strictures: a retrospective analysis

BackgroundThe outcomes of patients with refractory benign esophageal strictures (RBES) are unclear, and the clinical efficacy of dilation versus stent placement is lacking. Our objective was to explore the role of endoscopic dilation and stents placement in the management of RBES.MethodsRBES patients treated with dilation and stents in our hospital between January 2009 and December 2017 were included in this study. The primary outcomes were to assess clinical effectiveness and adverse events. The secondary outcome was to identify factors that predicted the dysphagia-free period.ResultsAmong 75 RBES patients (54 male; median age 59 years), 39 (52%), 20 (26.7%), 3 (4%), 10 (13.3%), and 3 (4%), were postsurgical, post-ESD, achalasia of cardia, caustic and mixed etiology, respectively. The median number of endoscopic therapy was 5 times (range 3, 21). Endoscopic therapy was successful in 46 patients (61.3%). Patients treated with dilation showed a higher success rate (70.9%, 39/55) than that treated with stents (35%, 7/20). Fifteen patients died during follow-up. Nineteen patients had adverse events after endoscopic therapy. In total, the mean dysphagia-free period was 3.4 months (95% CI, 2.5–4.3). The patients treated with dilation demonstrated a dysphagia-free period of 3.7 months (95% CI, 2.7–5), while patients treated with stents displayed a dysphagia-free period of 2.3 months (95% CI, 1.5–3). The dysphagia-free period had a linear growth trend over time, with an increase of 12 days per endoscopic therapy.ConclusionThe dysphagia-free period increased by 12 days per endoscopic therapy, so the endoscopic therapy tended to be effective in patients with RBES by increasing the dysphagia-free period. However, compared to dilation therapy, stent therapy was not effective in increasing the dysphasia-free period and reducing the times and frequency of dilation. In addition, univariate and multivariate analyses also indicated that etiology may predict the endoscopic therapy outcome.Trial registrationThis study was retrospectively registered and approved by the Ethics Committee of West China Hospital of Sichuan University (IRB number: ChiCTR1800016321).

FA07.04: THE ROLE OF ENDOSCOPIC DILATION AND STENTS IN THE REFRACTORY BENIGN ESOPHAGEAL STRICTURES: A RETROSPECTIVE ANALYSIS

Abstract Background The outcomes of patients with refractory benign esophageal strictures (RBES) was unclear and lacking in relative researches on the clinical efficacy of dilation compared with stent placement. Our objective was to explore the role of endoscopic dilation and stents in the management of RBES. Methods This study including patients with RBES (recurrence of dysphagia despite endoscopic therapy more than 3 sessions) by dilation and stents between January 2009 and December 2017. Endoscopic therapy success was defined as: before the end of the follow-up, no need for endoscopic interventions for at least 6 months. The primary outcome was to assess clinical effectiveness and adverse events. Secondary outcome was to identify factors that predicted the dysphagia-free period (the time interval of two subsequent endoscopic interventions). Multivariate analysis was used to estimate the risk factors influencing the treatment success. To explore the trend of dysphagia-free period along with times used hierarchical linear models. Results 75 patients (54 male; median age, 59 years) with RBES, 39 (52%), 20 (26.7%), 3 (4%), 10(13.3%), and 3(4%) were post-surgical, post-ESD, achalasia of cardia, caustic and mixed etiology, respectively. The median times of endoscopic therapy was 5 times (range 3, 21). Self-expandable metal stents (SEMSs) were placed in 20 patients (26.7%), and the success rate of patients treated with dilation (70.9%, 39/55) was higher than with stents (35%, 7/20). Fifteen patients died during follow-up. Nineteen patients had adverse events after endoscopic therapy. In total, the mean dysphagia-free period was 3.4 months (95% CI, 2.5–4.3). The dysphagia-free period of patients treated with dilation was 3.7months (95% CI, 2.7–5), and with stents was 2.3 months (95% CI, 1.5–3). The dysphagia-free period has linear growth trend with times, increased by 12 days per endoscopic therapy. Conclusion The dysphagia-free period increased by 12 days per endoscopic therapy, so the endoscopic dilation and stents tended to be effective in patients with RBES. Before the end of follow-up, nearly half of patients required continuing endoscopic dilation and stents, therefore, the patients with RBES may have negative long-term results. Stents therapy tended to not reduce the times and frequency of dilation. Disclosure All authors have declared no conflicts of interest.

Natural history and management of refractory benign esophageal strictures

The natural history of refractory benign esophageal strictures (RBES) is unclear, and surgery or percutaneous endoscopic gastrostomy (PEG) may be the only viable long-term options. The aim of the present study was to assess the long-term outcomes of patients with RBES. Clinical data of consecutive patients with RBES treated in the previous 15 years in 2 tertiary-care referral academic centers with specialized interest in esophageal stricture management were retrospectively analyzed. RBES was defined as the persistence and/or recurrence of dysphagia despite at least 5 dilation sessions and/or cycles with dilation to at least 14mm. Information regarding the use of dilation or stents and the dysphagia-free period between subsequent interventions and adverse events was collected. Clinical success was defined as no need for endoscopic interventions for at least 6 months; unfavorable outcomes were defined as the need for endoscopic treatment at the end of follow-up, surgery, or percutaneous endoscopic gastrostomy (PEG). Predictors of unfavorable outcomes were assessed by multivariate analysis. A linear mixed-effect model was used to measure dysphagia-free period changes over time. Overall, 70 patients with RBES (46 male; mean age 60 years) were followed for a mean of 43.9 months (range 3.7-157 months). Caustic, postradiotherapy, surgical, mixed, and postinflammatory etiology accounted for 10%, 14.3%, 31.4%, 40%, and 4.3% of causes, respectively. All patients underwent sequential sessions of pneumatic or bougie dilation, with a median of 15.5 dilation sessions per patient. Self-expandable metal stents (SEMSs) and biodegradable stents were placed in 18 (25.7%) and 14 (20%) patients, respectively. RBES resolution was achieved in only 22 of 70 (31.4%) patients. Two deaths (3%) were related to RBES. The success rate was lower in those who also were treated with endoprosthetics (odds ratio [OR] 3.7; 95% confidence interval [CI], 1.01-18.0). The mean dysphagia-free period was 3.3 months (95% CI, 2.4-4.1) for patients treated with dilation and 2.4 months (95% CI, 1.2-3.6) for those treated with stents (P= .062). Over time, the total dysphagia-free period increased at a rate of 4.1 days (95% CI, 1.7-6.4) per dilation. There was no difference in the rate of change across groups defined by sex (P= .976), age (P= .633), or endoscopic treatment (P= .267). Our multicenter series showed a disappointing long-term outcome for RBES, with only 1 of 3 achieving clinical resolution. The dysphagia-free period was relatively short, affecting the quality of life. Endoprosthetics did not appear to affect the natural history of RBES.

Endoscopic dilation combined with intramuscular injection of mitomycin C for benign esophageal strictures

Objective To evaluate the safety and efficacy of an endoscopic dilation in association with the intramuscular injection of either mitomycin C for benign esophageal strictures. Methods A total of 89 patients with benign esophageal strictures were retrospectively divided into 3 groups, including 30 cases of dilation combined with mitomycin C injection (mitomycin C group), 29 of dilation combined with dexamethasone injection (dexamethasone group) and 30 of dilation with saline injection (dilation group). The successful rate, complications and the clinical effect in the 3 groups were compared. Results The 89 patients all successfully received the procedure, with the endoscopic and clinical release. No massive hemorrhage occurred. In mitomycin C group, 1 case with major complication (perforation) and 7 minor complication occurred; 9 and 7 cases with minor complication occurred in dexamethasone group and dilation group, respectively. There were no significant difference of the complications in the 3 groups (P<0.05). The mean dysphagia-free period was 5.25±1.18 months in the mitomycin C group, 4.46±1.53 months in the dexamethasone group, and 3.03±1.62 months in the dilation group (P<0.05). Conclusion Endoscopic dilation with or without the intramuscular injection of either mitomycin C or dexamethasone are safe and effective. Dilation combined with drug injection may prolong the esophageal dysphagia-free period. Furthermore, mitomycin C injection may have the dominant effect. Key words: Mitomycin; Dexamethasone; Endoscopic dilation; Esophageal benign stricture

Endoscopic Corticosteroid Injections Do Not Reduce Dysphagia After Endoscopic Dilation Therapy in Patients With Benign Esophagogastric Anastomotic Strictures

Benign anastomotic strictures are often difficult to treat. We assessed the efficacy of adding corticosteroid injections to endoscopic dilation therapy with Savary bougienage. In a multicenter, double-blind trial, 60 patients (mean age, 63 ± 9 years; 78% male) with an untreated cervical anastomotic stricture after esophagectomy with gastric tube reconstruction and dysphagia for at least solid food were randomly assigned to groups given 4 quadrant injections of 0.5 mL triamcinolone (40 mg/mL, n = 29) or saline (controls, n = 31) into the stricture, followed by Savary dilation to 16 mm. Dysphagia, complications, and quality of life were assessed after 1 and 2 weeks and 1, 3, and 6 months. The primary end point was a dysphagia-free period of 6 months. In the corticosteroid group, 45% of the patients remained dysphagia-free for 6 months, compared with 36% of controls (relative risk, 1.26; 95% confidence interval, 0.68-2.36; P = .46). Median time to repeat dilation was 108 days (range, 15-180 days) in the corticosteroid group vs 42 days (range, 17-180 days) for controls (P = .11). A median number of 2 dilations (range, 1-7) was performed in the corticosteroid group vs 3 dilations (range, 1-9) in controls (relative risk, 0.76; 95% confidence interval, 0.42-1.38; P = .36). Two major intervention-related complications occurred, 1 submucosal laceration in the corticosteroid group and 1 hemorrhage in the control group. Four patients in the corticosteroid group, but none of the controls, developed Candida esophagitis (P = .03). Corticosteroid injections do not provide a statistically significant decrease in frequency of repeat dilations or prolongation of the dysphagia-free period in patients with benign anastomotic esophagogastric strictures. Dutch Trial Registration Number 2236.

Single and sequential biodegradable stent placement for refractory benign esophageal strictures: a prospective follow-up study

Although biodegradable stents do not require removal, a single biodegradable stent may only temporarily relieve dysphagia in patients with refractory benign esophageal stricture (RBES). The aim of this study was to evaluate the safety and long term efficacy of single and sequential biodegradable stent placement in patients with RBES. All patients who underwent biodegradable stent placement for RBES between August 2008 and March 2011 were prospectively followed to evaluate recurrent dysphagia and complication rates. In total, 59 stents were placed in 28 patients. Patients had previously been treated with multiple dilations (n = 20) or multiple dilations and non-biodegradable esophageal stenting (n = 8). A total of 13 patients underwent sequential biodegradable stent placement (median 3, range 2 - 8) during the study period. After initial stent placement, the median dysphagia-free period was 90 days (range 14 - 618 days). Clinical success (absence of dysphagia ≥ 6 months after stent placement) was achieved in seven patients (25 %) and major complications occurred in eight patients (29 %). After placement of a second biodegradable stent, the median dysphagia-free period was 55 days (range 25 - 700 days) and clinical success was achieved in 15 % of patients. After placement of a third stent, the median dysphagia-free period was 106 days (range 90 - 150 days), but none of the patients was clinically dysphagia-free. Placement of a single biodegradable stent is only temporarily effective in the vast majority of patients with RBES treated in a tertiary referral center. Sequential stenting may however be an option to avoid serial dilations.

Randomized Comparison of Three Palliative Regimens Including Brachytherapy, Photodynamic Therapy, and APC in Patients With Malignant Dysphagia (CONSORT 1a) (Revised II)

Because most esophageal cancers are diagnosed at an advanced stage, a majority of patients require palliative dysphagia treatment. Dysphagia severity and the need for repeated re-canalization procedures significantly affect patients' quality of life (QoL). The aim of this study was to establish whether combining argon plasma coagulation (APC) of the neoplastic esophageal tissue with another re-canalization method results in a longer dysphagia-free period compared with APC alone. We conducted a randomized trial in 93 patients with malignant dysphagia. Patients were followed until death. We compared three regimens of esophageal re-canalization; APC combined with high dose rate (HDR) brachytherapy, APC combined with photodynamic therapy (PDT), and APC alone. The primary outcome measure was the dysphagia-free period following randomization. Secondary measures were survival, QoL, treatment-associated complications, and treatment tolerance. A per-protocol analysis was carried out. The time to first dysphagia recurrence was significantly different between each combination treatment group and the control group (overall test: P=0.006; HDR vs. control, log-rank P=0.002, PDT vs. control, log-rank P=0.036), but not different between the combination groups (HDR vs. PDT, log-rank P=0.36). The median time to first dysphagia recurrence was 88, 59, and 35 days in the HDR, PDT, and control groups, respectively. There was no difference in overall survival between the study groups (P=0.27). No deaths, perforations, hemorrhages, or fistula formations were attributed to treatment. The only major complication was fever, occurring in three PDT patients. Minor complications were observed significantly more often in the combination treatment groups and included pain in both groups, transient dysphagia worsening, and skin sensitivity in the PDT group. The QoL 30 days after treatment in the HDR group was significantly better than in the other groups. In patients with inoperable esophageal cancer, palliative combination treatment of dysphagia with APC and HDR or PDT was significantly more efficient than APC alone, and was safe and well tolerated. APC combined with HDR resulted in fewer complications and better QoL than APC with PDT or APC alone (CONSORT 1b).

Therapeutic esophageal interventions for dysphagia and bleeding

This article reviews the most notable results of esophageal interventions for dysphagia and bleeding published in 2005. Long-term rubber tube placement was shown to be an interesting treatment option for difficult esophageal strictures. Two studies demonstrated that only 50% of patients who had undergone pneumatic dilation for achalasia were dysphagia-free after long-term follow-up. It was shown that patients with dysphagia from esophageal cancer should be treated by intraluminal radiotherapy (brachytherapy), whereas stent placement was preferable in those with a poor prognosis. Temporary stent placement is an option in patients undergoing radiotherapy for inoperable esophageal cancer to increase the dysphagia-free period. Two studies were published on the successful use of silicone-covered plastic stents for sealing of leaks after surgery of the esophagus. The optimal treatment for bleeding varices was confirmed to be endoscopic band ligation. A meta-analysis demonstrated that adding sclerotherapy to band ligation for secondary prophylaxis of bleeding varices had no effect on clinical outcome. In 2005, new techniques for the treatment of complicated strictures were presented. In addition, expanding indications for stents were reported. Finally, endoscopic band ligation was confirmed to be the most optimal technique for the treatment of varices.

4911 Argon plasma coagulation plus photodynamic therapy vs. argon plasma coagulation plus brachytherapy in palliation of malignant dysphagia: a prospective and randomized study.

Background: Argon plasma coagulation [APC], high-dose-rate brachytherapy [HDR], and photodynamic therapy [PDT] have been used in palliative treatment of malignant dysphagia. However, these methods as a monotherapy result in a relatively short period of good swallowing. The aim of this study is to evaluate whether an additional HDR or PDT after APC recanalization of malignant stenosis may prolong dysphagia-free period [DFP] in patients [pts] with non-operable esophageal or cardia cancer. Material:We considered for inclusion 72 pts (median age 70 yrs, range: 39-90) with malignant dysphagia who were not suitable for or did not accept radical treatment. However, 24 of them were excluded due to: bronchial involvement on EUS (n=9), esophago-bronchial fistula (n=4), perforation (n=1), lack of pts consent (n=7), death before randomization (n=3). The remaining 48 pts compromise study material. Methods: The stenosis was treated with APC until the patient could eat solid foods. After recanalization, pts were randomized to one of three groups: 1.additional HDR (n=16), 2.additional PDT (n=16), 3.observation without additional treatment (n=16). HDR was performed using 10-14 mm wide “bougie” applicator. Single dose of 12 Gy was given, specified 0.5 cm from the surface of the applicator. PDT was performed using Photosan-3 (dose 2.5 mg/kg) and low power laser irradiation (630 nm) to a dose of 250 J/cm of tumor. After the treatment pts were followed until death. Kaplan-Meier survival analysis of DFP was calculated for each group compared (fig). Results: The median DFP in HDR, PDT, and control group was 87 (range 16-219), 52.2 (16-303), and 27 (11-66) days respectively. The difference between HDR and control group and between PDT and control group were significant (log rank test, p=0.002and p=0.013 respectively). There was no significant difference between HDR and PDT group. Conclusions: These results show significant prolongation of DFP in pts who underwent additional HDR or PDT after recanalization with APC as compared to recanalization only. Background: Argon plasma coagulation [APC], high-dose-rate brachytherapy [HDR], and photodynamic therapy [PDT] have been used in palliative treatment of malignant dysphagia. However, these methods as a monotherapy result in a relatively short period of good swallowing. The aim of this study is to evaluate whether an additional HDR or PDT after APC recanalization of malignant stenosis may prolong dysphagia-free period [DFP] in patients [pts] with non-operable esophageal or cardia cancer. Material:We considered for inclusion 72 pts (median age 70 yrs, range: 39-90) with malignant dysphagia who were not suitable for or did not accept radical treatment. However, 24 of them were excluded due to: bronchial involvement on EUS (n=9), esophago-bronchial fistula (n=4), perforation (n=1), lack of pts consent (n=7), death before randomization (n=3). The remaining 48 pts compromise study material. Methods: The stenosis was treated with APC until the patient could eat solid foods. After recanalization, pts were randomized to one of three groups: 1.additional HDR (n=16), 2.additional PDT (n=16), 3.observation without additional treatment (n=16). HDR was performed using 10-14 mm wide “bougie” applicator. Single dose of 12 Gy was given, specified 0.5 cm from the surface of the applicator. PDT was performed using Photosan-3 (dose 2.5 mg/kg) and low power laser irradiation (630 nm) to a dose of 250 J/cm of tumor. After the treatment pts were followed until death. Kaplan-Meier survival analysis of DFP was calculated for each group compared (fig). Results: The median DFP in HDR, PDT, and control group was 87 (range 16-219), 52.2 (16-303), and 27 (11-66) days respectively. The difference between HDR and control group and between PDT and control group were significant (log rank test, p=0.002and p=0.013 respectively). There was no significant difference between HDR and PDT group. Conclusions: These results show significant prolongation of DFP in pts who underwent additional HDR or PDT after recanalization with APC as compared to recanalization only.