Per-oral endoscopic myotomy, 1000 cases later: pearls, pitfalls, and practical considerations

Efficacy of anterior versus posterior per-oral endoscopic myotomy for treating achalasia: a randomized, prospective study

BACKGROUND AND AIMS

Per-oral endoscopic myotomy (POEM) has been demonstrated to be safe and effective for treating achalasia. Two approaches-anterior myotomy and posterior myotomy-are used during POEM. However, little is known about the comparison between the 2 different approaches. The objective of the study is to compare the safety and short-term efficacy of the 2 approaches for treating achalasia.

METHODS

From October 2015 to December 2016, 63 consecutive patients with achalasia without prior treatment or sigmoid-type esophagus were prospectively recruited. They were randomly assigned to an anterior or posterior myotomy group. Clinical data about general characteristics, operative parameters, pre- and postoperative Eckardt score, esophageal manometry results, 24-hour pH test, and adverse events were recorded and compared between the 2 groups.

RESULTS

The anterior group included 31 patients and the posterior group 32 patients. All patients underwent POEM successfully, and treatment success (defined as an Eckardt score ≤3) was achieved in all patients during a mean follow-up of 15.5 months. Mean Eckardt score, lower esophageal sphincter pressure, and 4-second integrated relaxation pressure were significantly decreased (6.2 ± 1.3, 37.5 ± 6.7 mm Hg, and 27.3 ± 4.9 mm Hg vs .70 ± .70, 12.8 ± 2.8 mm Hg, and 11.1 ± 2.3 mm Hg, respectively; P < .01). There was no significant difference between the 2 groups in terms of general characteristics, treatment success, pre- and postoperative esophageal manometry, Eckardt score, and adverse events (P > .05).

CONCLUSIONS

The short-term treatment efficacy, manometry outcomes, and adverse events were comparable between the anterior and posterior myotomy groups. Large-scale studies with long-term follow-up are warranted for a more definitive conclusion. (Clinical trial registration number: ChiCTR-ICR-15007211.).

Endoscopic Myotomy for Foregut Motility Disorders

Peroral endoscopic myotomy (POEM) is an advanced endoscopic procedure classically performed for the treatment of achalasia. The procedure is based on principles of submucosal endoscopy and is composed of a mucosal incision, submucosal tunneling, myotomy, and mucosal closure. Multiple published studies that collectively include more than 6000 patients reported clinical success in more than 80% to 90% of patients. Recent literature also suggested durability of response over a medium-term follow-up. POEM is associated with a low rate of adverse events when performed by experienced operators. Gastroesophageal reflux is not infrequent after POEM but does not seem significantly different from reflux that occurs after Heller myotomy. POEM also seems to be effective in the treatment of spastic esophageal disorders (eg, jackhammer and diffuse esophageal spasm). Last, the role of gastric POEM (G-POEM) in the treatment of gastroparesis has been investigated in recent studies with promising results.

Treatment of Achalasia with Per-Oral Endoscopic Myotomy: Analysis of 50 Consecutive Patients

BACKGROUND

Peroral endoscopic myotomy (POEM) has become an acceptable incisionless treatment for achalasia based on encouraging outcomes in multiple series worldwide. This report reflects our early experience.

METHODS

Data were collected prospectively on all patients undergoing POEM between June 2011 and April 2016 under IRB approval. Diagnosis of achalasia was confirmed by standard preoperative work-up. Primary outcome was symptom relief, measured by Eckardt score. Secondary outcomes were operative time, length of stay (LOS), adverse events, failure, and recurrence.

RESULTS

Fifty patients were included; 30 were female. Mean age was 55.7 ± 17.7 years. Mean BMI was 29.5 ± 9.2. Median OR time was 133.5 minutes (range 70-462); average myotomy was 13.1 ± 2.3 cm. One early case was converted to a laparoscopic Heller myotomy due to extensive submucosal fibrosis from a recent Botox injection. Two cases were aborted; one due to extensive submucosal fibrosis and the other to intraoperative capnopericardium. Median LOS was 1 day (range 0.8-8). Two major complications occurred: intraoperative cardiac arrest due to capnopericardium and postoperative submucosal hemorrhage. There were no deaths. Mean postoperative Eckardt score was 1.0 ± 1.9 (range 0-8) at 2-6 weeks (vs. preoperative score 7.7 ± 2.8; P < .0001); mean dysphagia component 0.35 ± 0.28 (vs. preoperative score 2.6 ± 0.7; P < .0001). Two recurrences were identified, both at 6 months.

CONCLUSIONS

POEM is a safe and durable treatment for achalasia in the short term. We demonstrated marked improvement of symptoms in all completed cases. There was an acceptable serious adverse event rate of 4%, failure of 6% due to patient selection, and recurrences occurring in only 4% of cases.

Peroral endoscopic myotomy for the treatment of achalasia and other esophageal motor disorders: Short-term and medium-term results at a Mexican tertiary care center

INTRODUCTION AND AIMS

Achalasia is characterized by the absence of lower esophageal sphincter relaxation and esophageal aperistalsis. Diagnosis is confirmed through high-resolution esophageal manometry. Laparoscopic myotomy is the standard treatment, but peroral endoscopic myotomy (POEM) is a safe and effective alternative, with good short-term and medium-term results. Our aim was to describe the short-term and medium-term experience with POEM at a tertiary care center.

MATERIALS AND METHODS

The study was conducted within the time frame of November 2014 and February 2017. Treatment-naïve achalasia patients and previously-treated achalasia patients that were candidates for POEM were included. A protocolized 24-month follow-up was carried out.

RESULTS

Fifty procedures were included and 31 (68%) were performed on women. Forty-one (82%) of the procedures were carried out on previously untreated patients, 7 (14%) were performed on previously treated patients, and 2 (4%) of the patients had redo-POEM. The mean age of the patients was 48.8±14.1 years. The pre-POEM Eckardt score was 9 and the integrated relaxation pressure was 24.4mmHg. Sixty-eight percent of the patients had type ii achalasia. Procedure time was 80min and myotomy length was 12.6cm. Hospital stay was 3 days and subcutaneous emphysema was the most common adverse event (30%). A total of 22/50 (44%) patients reached the 24-month follow-up, maintaining the Eckardt score and the decrease in the integrated relaxation pressure. There were no deaths. A total of 47.5% of the patients had a positive pH-study at 6 months, 15% had clinical reflux, and 35% presented with mild esophagitis. All the patients were adequately controlled with proton pump inhibitors.

CONCLUSION

POEM is safe and effective in the short term and medium term for the treatment of achalasia and other esophageal motor disorders in Mexican patients.

Two penetrating vessels as a novel indicator of the appropriate distal end of peroral endoscopic myotomy

BACKGROUND AND AIM

One of the challenges during peroral endoscopic myotomy (POEM) is ensuring the appropriate length of myotomy on the gastric side. To determine the appropriate distal end of the gastric myotomy, we focused on the two penetrating vessels (TPVs) found in the gastric cardia during POEM. In the present study, we evaluated whether the TPVs could serve as an accurate indicator of the appropriate distal end of the gastric myotomy.

METHODS

All patients who underwent POEM between March and August 2016 were included for this study. When making the submucosal tunnel in the 5 o'clock direction into the stomach, two vessels penetrating through the circular muscle along the edge of oblique muscle in the cardia can be exposed. We designated these two vessels as TPVs. The myotomy was extended until the second TPVs was exposed. The anal end of the submucosal tunnel was confirmed by the double-scope POEM technique, and the length from the gastroesophageal junction to the anal side end of the myotomy was measured by the scale on the endoscope.

RESULTS

Among 37 patients who underwent myotomy in the 5 o'clock position, TPVs were found in 34 patients (91.2%). Sufficient submucosal tunneling on the gastric side was confirmed by the double-scope POEM technique in these 34 patients. Median length of the gastric myotomy was 3.0 cm (range 2-4 cm).

CONCLUSION

TPVs appears to be a simple and reliable indicator to determine the appropriate distal end of myotomy.

Current Status of Peroral Endoscopic Myotomy

Peroral endoscopic myotomy (POEM) has been established as an optional treatment for achalasia. POEM is an endoluminal procedure that involves dissection of esophageal muscle fibers followed by submucosal tunneling. Inoue first attempted to use POEM for the treatment of achalasia in humans. Expanded indications of POEM include classic indications such as type I, type II, type III achalasia, failed prior treatments, including Botulinum toxin injection, endoscopic balloon dilation, laparoscopic Heller myotomy, and hypertensive motor disorders such as diffuse esophageal spasm, jackhammer esophagus. Contraindications include prior radiation therapy to the esophagus and prior extensive esophageal mucosal resection/ablation involving the POEM field. Most of the complications are minor and self-limited and can be managed conservatively. As POEM emerged as the main treatment for achalasia, various adaptations to tunnel endoscopic surgery have been attempted. Tunnel endoscopic surgery includes POEM, peroral endoscopic tumor resection, gastric peroral endoscopic pyloromyotomy. POEM has been widely accepted as a treatment for all types of achalasia, even for specific cases such as achalasia with failed prior treatments, and hypertensive motor disorders.

Outcomes of anterior myotomy versus posterior myotomy during POEM: a randomized pilot study

BACKGROUND AND STUDY AIMS

 Peroral endoscopic myotomy (POEM) can be performed via an anterior or posterior approach, depending on the operator's preference. Data are lacking on comparative outcomes of both approaches.

PATIENTS AND METHODS

 This is a pilot randomized study comparing endoscopic anterior and posterior myotomy during POEM in patients with Achalasia cardia (AC). Patients were randomized into 2 groups (n = 30 in each group); anterior myotomy group (AG) and posterior myotomy group (PG) and were followed at 1, 3 and 6 months after POEM.

RESULTS

 Technical success was achieved in 100 % of cases in both groups and total operative time was comparable (AG - 65 ± 17.65 minutes versus PG - 61.2 ± 16.67; P  = 0.38); Mucosotomies were more frequent in AG (20 % vs 3.3 %; P  = 0.02). Difference in other perioperative adverse events (AE) including insufflation-related AE and bleeding in both groups were statistically insignificant. At 1-month follow-up Eckardt score AG 0.57 ± 0.56 vs PG 0.53 ± 0.71; ( P  = 0.81), mean LES pressure AG 11.93 ± 6.36 vs PG 11.77 ± 6.61; ( P  = 0.59) and esophageal emptying on timed barium swallow at 5 minutes AG 1.32 ± 1.08 cm vs PG 1.29 ± 0.79 cm; ( P  = 0.09) were comparable in both groups. At 3 months, Eckardt score (0.52 ± 0.59 vs 0.63 ± 0.62; P  = 0.51) was similar in both groups. Incidence of esophagitis on EGD was comparable in both groups (24 % vs 33.3 %; P  = 0.45), however, pH metry at 3 months showed significantly more esophageal acid exposure in posterior group (2.98 % ± 4.24 vs 13.99 % ± 14.48; P  < 0.01). At 6 months clinical efficacy and LES pressures were comparable in both groups.

CONCLUSION

 Anterior and posterior approaches to POEM seem to have equal efficacy. However, the occurrence of mucosotomies was higher in the anterior myotomy group and acid exposure was higher with the posterior myotomy approach during POEM.

Comparison of outcomes of laparoscopic Heller myotomy versus per-oral endoscopic myotomy for management of achalasia

Achalasia is a rare disorder that has several treatment options. The gold standard of treatment is a surgical myotomy called a laparoscopic Heller myotomy (LHM). More recently, an endoscopic myotomy has become an option as well, called per-oral endoscopic myotomy (POEM). An achalasia registry was queried for patients undergoing either LHM or POEM at Baylor University Medical Center at Dallas. Patient demographics, preoperative and postoperative data points, and Eckardt scores were collected. The patients were further stratified into their follow-up intervals, immediate postoperative and long-term follow-up, to assess surgical success. A subset analysis was done for success of treatment for patients who had redo surgery versus those undergoing the procedure for the first time. There were 12 patients in the POEM group and 11 patients in the LHM group. Both groups demonstrated mean lower esophageal sphincter pressures with failure to relax. Procedure length and hospital length of stay were similar between the two groups. There were three adverse events in each group, but none altered the patient's postoperative clinical course. Eckardt scores, used to assess success of the surgery, were 82% for POEM patients and 66% for LHM patients after 6 months. The outcomes for POEM and LHM in our early experience are similar to those reported in the literature for high-volume centers managing achalasia.

Adverse events during and after per-oral endoscopic myotomy: prevention, diagnosis, and management

Per-oral endoscopic myotomy (POEM) has surfaced as an effective endoscopic treatment modality for achalasia cardia (AC). Promising results in short- and mid-term follow-up studies have increased the use of POEM for the management of AC. POEM can be safely performed in an endoscopy suit, and major adverse events (AEs) are uncommon. AEs encountered during POEM or during the perioperative period principally include insufflation-related AEs, mucosal injuries, bleeding, pain, and aspiration pneumonia. Most insufflation-related AEs do not require an active intervention and therefore should not be considered as AEs in the true sense. When management of AEs is required, most intraoperative AEs can be managed at the same time without untoward consequences. Occurrences of AEs lessen after completion of the learning curve. However, experience alone does not ensure "zero" incidence of AEs, and early recognition remains essential. Postoperative AEs, like leaks, delayed bleeding, and delayed mucosal perforations, may pose special challenges for diagnosis and management. There is no standardized classification system for grading the severity of AEs associated with POEM, resulting in wide variation in their reported occurrences. Uniform reporting of AEs is not only crucial to comprehensively analyze the safety of POEM but also for comparison with other established treatment modalities like Heller's myotomy. GERD is an important long-term AE after POEM. Unlike the perioperative AEs, little is known regarding the intraoperative or patient-related factors that influence the occurrence of post-POEM GERD. Large prospective studies with long-term follow-up are required to determine the procedural factors associated with GERD after POEM.

Clinical Practice Update: The Use of Per-Oral Endoscopic Myotomy in Achalasia: Expert Review and Best Practice Advice From the AGA Institute

The purpose of this review is to describe a place for per-oral endoscopic myotomy (POEM) among the currently available robust treatments for achalasia. The recommendations outlined in this review are based on expert opinion and on relevant publications from PubMed and EMbase. The Clinical Practice Updates Committee of the American Gastroenterological Association proposes the following recommendations: 1) in determining the need for achalasia therapy, patient-specific parameters (Chicago Classification subtype, comorbidities, early vs late disease, primary or secondary causes) should be considered along with published efficacy data; 2) given the complexity of this procedure, POEM should be performed by experienced physicians in high-volume centers because an estimated 20-40 procedures are needed to achieve competence; 3) if the expertise is available, POEM should be considered as primary therapy for type III achalasia; 4) if the expertise is available, POEM should be considered as treatment option comparable with laparoscopic Heller myotomy for any of the achalasia syndromes; and 5) post-POEM patients should be considered high risk to develop reflux esophagitis and advised of the management considerations (potential indefinite proton pump inhibitor therapy and/or surveillance endoscopy) of this before undergoing the procedure.

A novel strategy to initiate a peroral endoscopic myotomy program

OBJECTIVES

The standard of care for achalasia remains laparoscopic Heller myotomy with partial fundoplication. Peroral endoscopic myotomy (POEM) has been introduced as an alternative, but safety and long-term comparative efficacy are not yet established. We report our experience in developing a POEM program using a novel hybrid approach.

METHODS

We developed a hybrid approach to POEM with a POEM followed by laparoscopic evaluation, extension of the myotomy, if necessary, and partial fundoplication. We reviewed the results of the programme from April 2012 until May 2015. Starting in 2014, we began offering patients stand-alone POEM. Patient data were collected. Preoperative and postoperative Eckardt scores were compared.

RESULTS

A total of 28 patients underwent POEM or POEM plus laparoscopic evaluation with partial fundoplication. Patient characteristics and perioperative and postoperative data were recorded. The median preoperative Eckardt score was 6 (range 4-11). The mean follow-up period was 136 days (range 41-330) and the median postoperative Eckardt score was 0 (range 0-6) at 6 weeks. Of our initial 10 patients, 6 required laparoscopic extension of the myotomy; 7 subsequent patients did not require an additional myotomy. Three patients who underwent POEM without laparoscopy continued to have dysphagia postoperatively. One patient had an attempted POEM that was aborted secondary to bleeding, and a standard laparoscopic modified Heller myotomy with partial fundoplication was performed.

CONCLUSIONS

The excellent results of laparoscopic myotomy with partial fundoplication are challenging to duplicate during the initial adoption of a POEM approach. We present a program developed to steepen the learning curve and enhance patient safety while implementing this new procedure.

Recent Advances in Endoscopy

In this narrative review, invited by the Editors of Gastroenterology, we summarize recent advances in the field of gastrointestinal endoscopy. We have chosen articles published primarily in the past 2-3 years. Although a thorough literature review was performed for each topic, the nature of the article is subjective and systematic and is based on the authors' experience and expertise regarding articles we believed were most likely to be of high clinical and scientific importance.

Peroral endoscopic myotomy using FlushKnife BT: a single-center series

BACKGROUND AND STUDY AIMS

Peroral endoscopic myotomy (POEM) is an evolving new treatment strategy for achalasia. Although several kinds of electrosurgical knives have been used in performing POEM, the best device has yet to be determined. The FlushKnife BT is a waterjet-emitting short needle-knife with a small ball tip (BT) that offers the potential to perform all aspects of POEM with a single device. In this study, we evaluated the safety and efficiency of the FlushKnife BT for POEM.

PATIENTS AND METHODS

 A total of 54 consecutive patients with achalasia and other spastic esophageal motility disorders, such as jackhammer esophagus or distal esophageal spasm, who underwent POEM between January 2016 and August 2016, were included in this retrospective study.

RESULTS

 The median operation time was 73.0 minutes (range 39 - 184 minutes). All procedures were completed using only the FlushKnife BT without changing to any other electrosurgical instrument. The median number of additional submucosal injections with an injection needle was 0 (range 0 - 1). Endoscopic vessel sealing was performed a mean of 3 times (range 0 - 7). The median number of bleeding episodes requiring treatment with hemostatic forceps was 0 (range 0 - 5). There were no significant adverse events. Seven of 52 patients (13.5 %) reported symptoms of gastroesophageal reflux disease such as heartburn or acid reflux at 3 month follow-up.

CONCLUSIONS

 The FlushKnife BT enabled POEM to be performed with very few device exchanges, either for re-injection or to control intraoperative bleeding. In this uncontrolled case series, the ability of the FlushKnife BT to perform nearly all aspects of the POEM procedure seems to make it particularly well suited to this procedure.

Achalasia: current therapeutic options

Achalasia is a chronic incurable esophageal motility disorder characterized by impaired lower esophageal sphincter (LES) relaxation and loss of esophageal peristalsis. Although rare, it is currently the most common primary esophageal motility disorder, with an annual incidence of around 1.6 per 100,000 persons and prevalence of around 10.8/100,000 persons. Symptoms of achalasia include dysphagia to both solids and liquids, regurgitation, aspiration, chest pain and weight loss. As the underlying etiology of achalasia remains unclear, there is currently no curative treatment for achalasia. Management of achalasia mainly involves improving the esophageal outflow in order to provide symptomatic relief to patients. The most effective treatment options for achalasia include pneumatic dilation, Heller myotomy and peroral endoscopic myotomy (POEM), with the latter increasingly emerging as the treatment of choice for many patients. This review focusses on evidence for current and emerging treatment options for achalasia with a particular emphasis on POEM.

POEM for special patient cohorts: A review

Peroral endoscopic myotomy (POEM) is a natural orifice, translumenal endoscopic surgical procedure that achieves endoscopic myotomy by conducting a submucosal tunnel as an operating space. It is conventionally performed in achalasia. Recently, several centers worldwide have reported the feasibility of this procedure not only in early achalasia but also in other particular patient cohorts. Possible indications for POEM include previously failed Heller myotomy, pneumatic balloon dilatation or POEM, sigmoid achalasia, pediatric patients, spastic esophagus disorders, Zenker's diverticulum and gastroparesis. However, its application in large numbers of special patient groups awaits knowledge of the long-term outcome and greater experience with POEM.

Achalasia

Achalasia is a rare neurogenic motility disorder of the esophagus, occurring in approximately 0.11 cases per 100,000 children. The combination of problems (aperistalsis, hypertensive lower esophageal sphincter (LES), and lack of receptive LES relaxation) results in patients having symptoms of progressive dysphagia, weight loss, and regurgitation. Treatment modalities have evolved over the past few decades from balloon dilation and botulinum toxin injection to laparoscopic Heller myotomy and endoscopic myotomy. Most data on achalasia management is extrapolated to children from adult experience. This article describes understanding of the pathogenesis and discusses newer therapeutic techniques as well as controversies in management.

Current status of achalasia management: a review on diagnosis and treatment

BACKGROUND

Achalasia is a rare esophageal motility disorder that is characterized by loss of peristalsis and failure of relaxation of the lower esophageal sphincter (LES), particularly during swallowing. This review focuses on the diagnosis of esophageal motility disorders as defined by the Chicago Classification ver 3.0, and presents management options with regard to per-oral endoscopic myotomy (POEM) as the treatment of choice.

METHODS

A concise review of literature was performed for articles related to the management of achalasia, and this was contrasted with our institution's current practice.

RESULTS

Achalasia is still incompletely understood, and management is focused on establishing a proper diagnosis, and relieving the obstructive symptoms.

CONCLUSIONS

Achalasia should be considered when dysphagia is present, and not otherwise caused by an obstruction or inflammation, and when criteria is met as per the Chicago Classification ver 3.0. Lowering LES tone and disruption of LES can be accomplished by various methods, most notably pneumatic balloon dilatation and surgical myotomy. POEM has been gaining momentum as a first line therapy for achalasia symptoms, and can be considered an important tool for motility disorders of the esophagus.

Re-appraisal and consideration of minimally invasive surgery in colorectal cancer

Throughout history, surgeons have been on a quest to refine the surgical treatment options for their patients and to minimize operative trauma. During the last three decades, there have been tremendous advances in the field of minimally invasive colorectal surgery, with an explosion of different technologies and approaches offered to treat well-known diseases. Laparoscopic surgery has been shown to be equal or superior to open surgery. The boundaries of laparoscopy have been pushed further, in the form of single-incision laparoscopy, natural-orifice transluminal endoscopic surgery and robotics. This paper critically reviews the pathway of development of minimally invasive surgery, and appraises the different minimally invasive colorectal surgical approaches available to date.

Full-thickness myotomy is associated with higher rate of postoperative gastroesophageal reflux disease

AIM

To compare long-term occurrence of gastroesophageal reflux disease (GERD) between two different types of peroral endoscopic myotomy (POEM) for achalasia.

METHODS

We included all patients with achalasia who underwent POEM at our hospital from August 2011 to October 2012 and had complete GERD evaluation with ≥ 3 years of follow-up. They were divided into circular or full-thickness myotomy groups according to the depth of myotomy. Demographics, Eckardt score, manometry results, 24-h pH monitoring, and GERD symptoms were recorded and compared between the two groups.

RESULTS

We studied 56 patients (32 circular myotomy and 24 full-thickness myotomy) with complete GERD evaluation. There was no significant difference between the two groups in terms of treatment success (defined as Eckardt score ≤ 3), postoperative Eckardt score, mean basal lower esophageal sphincter pressure, and 4-s integrated relaxation pressure (4sIRP). Postoperative abnormal esophageal acid exposure was found in 25 patients (44.6%). A total of 13 patients (23.2%) had GERD symptoms and 12 had esophagitis (21.4%). Clinically relevant GERD (abnormal esophageal acid exposure associated with GERD symptoms and/or esophagitis) was diagnosed in 13 patients (23.2%). Multivariate analysis revealed that full-thickness myotomy and low level of postoperative 4sIRP were predictive factors for clinically relevant GERD.

CONCLUSION

Efficacy and manometry are comparable between achalasia patients treated with circular or full-thickness myotomy. But patients with full-thickness myotomy and low postoperative 4sIRP have more GERD.

Complications of submucosal endoscopy

Submucosal endoscopy essentially regroups peroral endoscopic esophageal myotomy (POEM) and, more recently, pyloromyotomy and tunnel tumor resections. The complication rate of POEM is between 5% and 10%. Complications include gas-related complications, mucosal tears, and bleeding, and are usually managed conservatively or with non-surgical procedures. Only one case of death has been reported. The most commonly identified risk factors for complicated procedures in POEM are short experience with the technique and sigmoid-type esophagus. The rate of gastro-esophageal reflux (GERD) is between 10% and 30% depending on the definitions, with a good clinical response to proton pump inhibitors. For the techniques other than POEM, the number of cases reported is too small to allow identification of the complications, which, in addition, probably vary depending on the organ involved. The management of gas-related complications is conservative and sometimes requiring percutaneous exsufflation (capnoperitoneum) or drainage. The endoscopic management of mucosal tears essentially involves clip placement and, in case of bleeding, the usual hemostasis techniques including stent placement. Importantly, following a rigorous and appropriate learning program is essential to minimize the risk of complications, particularly for specialists with a short experience in the technique.