Myotomy technique and esophageal contractility impact blown-out myotomy formation in achalasia: an in silico investigation

Enhancing Chicago Classification diagnoses with functional lumen imaging probe-mechanics (FLIP-MECH)

BACKGROUND

Esophageal motility disorders can be diagnosed by either high-resolution manometry (HRM) or the functional lumen imaging probe (FLIP) but there is no systematic approach to synergize the measurements of these modalities or to improve the diagnostic metrics that have been developed to analyze them. This work aimed to devise a formal approach to bridge the gap between diagnoses inferred from HRM and FLIP measurements using deep learning and mechanics.

METHODS

The "mechanical health" of the esophagus was analyzed in 740 subjects including a spectrum of motility disorder patients and normal subjects. The mechanical health was quantified through a set of parameters including wall stiffness, active relaxation, and contraction pattern. These parameters were used by a variational autoencoder to generate a parameter space called virtual disease landscape (VDL). Finally, probabilities were assigned to each point (subject) on the VDL through linear discriminant analysis (LDA), which in turn was used to compare with FLIP and HRM diagnoses.

RESULTS

Subjects clustered into different regions of the VDL with their location relative to each other (and normal) defined by the type and severity of dysfunction. The two major categories that separated best on the VDL were subjects with normal esophagogastric junction (EGJ) opening and those with EGJ obstruction. Both HRM and FLIP diagnoses correlated well within these two groups.

CONCLUSION

Mechanics-based parameters effectively estimated esophageal health using FLIP measurements to position subjects in a 3-D VDL that segregated subjects in good alignment with motility diagnoses gleaned from HRM and FLIP studies.

Automatic three-dimensional reconstruction of the oesophagus in achalasia patients undergoing POEM: an innovative approach for evaluating treatment outcomes

BACKGROUND AND AIMS

Peroral endoscopic myotomy (POEM) is a standard treatment option for achalasia patients. Treatment response varies due to factors such as achalasia type, degree of dilatation, pressure and distensibility indices. We present an innovative approach for treatment response prediction based on an automatic three-dimensional (3-D) reconstruction of the tubular oesophagus (TE) and the lower oesophageal sphincter (LES) in patients undergoing POEM for achalasia.

METHODS

A software was developed, integrating data from high-resolution manometry, timed barium oesophagogram and endoscopic images to automatically generate 3-D reconstructions of the TE and LES. Novel normative indices for TE (volume×pressure) and LES (volume/pressure) were automatically integrated, facilitating pre-POEM and post-POEM comparisons. Treatment response was evaluated by changes in volumetric and pressure indices for the TE and the LES before as well as 3 and 12 months after POEM. In addition, these values were compared with normal value indices of non-achalasia patients.

RESULTS

50 treatment-naive achalasia patients were enrolled prospectively. The mean TE index decreased significantly (p<0.0001) and the mean LES index increased significantly 3 months post-POEM (p<0.0001). In the 12-month follow-up, no further significant change of value indices between 3 and 12 months post-POEM was seen. 3 months post-POEM mean LES index approached the mean LES of the healthy control group (p=0.077).

CONCLUSION

3-D reconstruction provides an interactive, dynamic visualisation of the oesophagus, serving as a comprehensive tool for evaluating treatment response. It may contribute to refining our approach to achalasia treatment and optimising treatment outcomes.

TRIAL REGISTRATION NUMBER

22-0149.

Recent Advancement and Future Perspective of Per Oral Endoscopic Myotomy

Per oral endoscopic myotomy (POEM) has emerged as a preferred approach for the treatment of idiopathic achalasia and various esophageal motility disorders, offering a minimally invasive alternative to traditional laparoscopic Heller's myotomy. Over the past decade, POEM has solidified its status as the primary therapeutic choice in these conditions through constant improvements. Its evolution has been marked by continuous progress, driven by the integration of innovative technologies and sophisticated techniques. Notable advancements in the techniques include the advent of shorter myotomies and sling fiber-preserving gastric myotomies. The introduction of novel image-enhanced endoscopic techniques, such as red dichromatic imaging and much safer bipolar devices, promises to enhance safety and reduce the technical demands of the POEM procedure. Furthermore, significant strides have been made in understanding gastroesophageal reflux (GERD) following POEM, enabling the differentiation of "true reflux" from acidification resulting from fermentation through manual pH tracing assessment. This distinction aids in identifying cases necessitating treatment with proton pump inhibitors. Other treatment strategies of post-POEM GERD have expanded to the incorporation of NOTES fundoplication and device-assisted fundoplication if the necessity arises. This comprehensive review delves into recent developments in POEM, encompassing technical variations, the assessment and management of post-POEM reflux, outcomes in special populations, and future prospects. By exploring these facets, we aim to provide a comprehensive overview of the current state of POEM, shedding light on its evolution and the promising directions it is poised to take in the field of third-space endoscopy.

Pneumatic dilation for achalasia in the "POEM era": Still a valuable ally

Endoscopic treatments such as peroral endoscopic myotomy (POEM) and pneumatic dilation (PD) are commonly used to treat achalasia. Although POEM has gained popularity due to its high efficacy, the technique is more complex and may be associated with a higher risk of long-term complications compared to PD. This narrative review will focus on efficacy and safety of PD and POEM, and their suitability for different patient populations. While evidence suggests that POEM may be preferred for type III achalasia, PD remains a valuable alternative for patients with a straight, non-dilated esophagus, who prioritize the preservation of anatomical integrity and a lower risk of post-procedural gastroesophageal reflux disease (GERD). While PD carries a non negligibile risk of perforation, it has an excellent safety profile in terms of GERD and is minimally likely to cause permanent esophageal deformation. PD can be repeated with minimal risks to maintain symptom relief, whereas reversing permanent anatomical modifications related to POEM is difficult. The choice of treatment for achalasia should be patient-tailored, considering benefits and drawbacks of each intervention. The importance of personalized approach in the "POEM era" is highlighted, emphasizing the reasons why PD should still be considered a valuable option in the therapeutic armamentarium for achalasia. Areas requiring further research will be also outlined.

Presence of esophageal contractility after achalasia treatment is associated with improved esophageal emptying

BACKGROUND AND AIMS

Some achalasia patients exhibit esophageal contractile activity on follow-up after treatment, yet its importance remains unclear. We aimed to identify factors associated with presence of contractility after treatment and to assess its impact on timed barium esophagram (TBE) and clinical outcomes.

METHODS

Patients with type I or II achalasia on baseline high-resolution manometry (HRM) who completed HRM, TBE, and functional lumen imaging probe (FLIP) after treatment were retrospectively identified. Contractility was defined on post-treatment HRM as presence of at least 1 supine swallow with DCI ≥100 mmHg s cm.

KEY RESULTS

One hundred twenty-two patients were included (mean age 48 ± 17 years, 50% female). At follow-up evaluation after treatment (54% peroral endoscopic myotomy, 24% pneumatic dilation, 22% laparoscopic Heller myotomy), 61 (50%) patients had contractility on HRM. Patients with contractility (compared to those without) more frequently had type II achalasia (84% vs 57%, p = 0.001) and a post-treatment normal EGJ opening classification on FLIP (69% vs 49%; p < 0.001). In the subgroup of patients with post-treatment integrated relaxation pressure <15 mmHg and normal EGJ opening on FLIP (n = 53), those with contractility had a lower median column height on TBE at 1 min (4 vs 7 cm, p = 0.002) and 5 min (0 vs 5 cm, p = 0.001). In patients with "abnormal" EGJ metrics, patients with contractility showed lower symptom scores (median Eckardt score 2 vs 3, p = 0.03).

CONCLUSIONS & INFERENCES

Occurring more frequently in type II achalasia, and if adequate EGJ opening is achieved after treatment, esophageal contractility may contribute to improved esophageal emptying and improved symptoms in non-spastic achalasia. Preservation of esophageal body muscle could improve outcomes in these patients.

Salvage peroral endoscopic myotomy is a promising treatment for achalasia after myotomy failure

BACKGROUND AND AIMS

Reintervention modalities after myotomy failure in achalasia patients have yet to be established. The efficacy and safety of salvage peroral endoscopic myotomy (POEM) for treatment of achalasia after myotomy failure were evaluated in the study.

METHODS

Between August 2011 and August 2021 at the Endoscopy Center of Zhongshan Hospital, 219 achalasia patients who had previously undergone a myotomy underwent a salvage POEM and were thus retrospectively enrolled in this study. After propensity score matching (PSM), operation-related parameters were compared between the salvage POEM group and the naïve POEM group. Subgroup analysis was performed between patients with previous Heller myotomy (HM) and patients with previous POEM.

RESULTS

With similar baseline characteristics between both groups after PSM, the salvage POEM group presented with shorter tunnel length (11.8 ± 2.2 cm vs 12.8 ± .9 cm, P < .0001) and myotomy length (9.8 ± 2.0 cm vs 10.4 ± 1.0 cm, P < .0001) than the naïve POEM group. No significant differences were found in procedure-related adverse events between patients of salvage POEM and naïve POEM. The primary outcome of treatment success occurred in 175 of 193 patients (90.7%) in the salvage POEM group versus 362 of 374 patients (96.8%) in the naïve POEM group (P = .0046). At a 2- and 5-year follow-up, significantly higher rates of clinical failures were observed in the previous HM subgroup than in the previous POEM subgroup (P = .0433 and P = .0230, respectively).

CONCLUSIONS

Salvage POEM after a previous myotomy failure, especially after a POEM failure, is a promising treatment option because it has a durable clinical relief rate.

MRI-MECH: mechanics-informed MRI to estimate esophageal health

Dynamic magnetic resonance imaging (MRI) is a popular medical imaging technique that generates image sequences of the flow of a contrast material inside tissues and organs. However, its application to imaging bolus movement through the esophagus has only been demonstrated in few feasibility studies and is relatively unexplored. In this work, we present a computational framework called mechanics-informed MRI (MRI-MECH) that enhances that capability, thereby increasing the applicability of dynamic MRI for diagnosing esophageal disorders. Pineapple juice was used as the swallowed contrast material for the dynamic MRI, and the MRI image sequence was used as input to the MRI-MECH. The MRI-MECH modeled the esophagus as a flexible one-dimensional tube, and the elastic tube walls followed a linear tube law. Flow through the esophagus was governed by one-dimensional mass and momentum conservation equations. These equations were solved using a physics-informed neural network. The physics-informed neural network minimized the difference between the measurements from the MRI and model predictions and ensured that the physics of the fluid flow problem was always followed. MRI-MECH calculated the fluid velocity and pressure during esophageal transit and estimated the mechanical health of the esophagus by calculating wall stiffness and active relaxation. Additionally, MRI-MECH predicted missing information about the lower esophageal sphincter during the emptying process, demonstrating its applicability to scenarios with missing data or poor image resolution. In addition to potentially improving clinical decisions based on quantitative estimates of the mechanical health of the esophagus, MRI-MECH can also be adapted for application to other medical imaging modalities to enhance their functionality.

Esophageal diverticula: from diagnosis to therapeutic management-narrative review

Background and Objective

Esophageal diverticulum (ED) is a relatively rare condition, characterized by high etio- and pathophysiological versatility, with an uncommon clinical impact, consequently requiring a complete and complex diagnostic evaluation, so that the therapeutic decision is "appropriate" to a specific case. The aim of the paper is, therefore, a reassessment of the diagnostic possibilities underlying the establishment of the therapeutic protocol and the available therapeutic resources, making a review of the literature, and a non-statistical retrospective analysis of cases hospitalized and operated in a tertiary center.

Methods

Thus, classical investigations (upper digestive endoscopy, barium swallow) need to be correlated with complex, manometric, and imaging evaluations with direct implications in therapeutic management. Moreover, in the absence of a precise etiology, the operative indication needs to be established sparingly, with the imposition of the identification and interception of the pathophysiological mechanisms through the therapeutic gesture.

Key Content and Findings

The identification of the pathophysiological mechanisms is mandatory for the management of diverticular disease, the result obtained-restoring swallowing and comfort/good quality of life in the postoperative period-is directly related to the chosen therapeutic procedure. In addition, management appears to be a difficult goal in the context of the low incidence of ED but also of the results that emphasize important differences in the reports in the medical literature. Although ED is a benign condition, surgical techniques are demanding, impacted by significant morbidity and mortality. The causes of these results are multiple: possible localizations anywhere in the esophagus, diverticulum size/volume from a few millimeters to an impressive one, over 10-12 cm, metabolic impact in direct relation to the alteration swallowing, numerous diverticular complications but, perhaps most importantly, alteration of the quality of the diverticular wall by inflammatory phenomena, with an impact on the quality of the suture.

Conclusions

The accumulation of cases in a tertiary profile center, with volume/hospital, respectively volume/surgeon + gastroenterologist could be a solution in improving the results. One consequence would be the identification of alternative solutions to open surgical techniques, a series of minimally invasive or endoscopic variants can refine these results.

A mechanics-based perspective on the pressure-cross-sectional area loop within the esophageal body

Introduction: Plotting the pressure-cross-sectional area (P-CSA) hysteresis loops within the esophagus during a contraction cycle can provide mechanistic insights into esophageal motor function. Pressure and cross-sectional area during secondary peristalsis can be obtained from the functional lumen imaging probe (FLIP). The pressure-cross-sectional area plots at a location within the esophageal body (but away from the sphincter) reveal a horizontal loop shape. The horizontal loop shape has phases that appear similar to those in cardiovascular analyses, whichinclude isometric and isotonic contractions followed by isometric and isotonic relaxations. The aim of this study is to explain the various phases of the pressurecross-sectional area hysteresis loops within the esophageal body. Materials and Methods: We simulate flow inside a FLIP device placed inside the esophagus lumen. We focus on three scenarios: long functional lumen imaging probe bag placed insidethe esophagus but not passing through the lower esophageal sphincter, long functional lumen imaging probe bag that crosses the lower esophageal sphincter, and a short functional lumen imaging probe bag placed in the esophagus body that does not pass through the lower esophageal sphincter. Results and Discussion: Horizontal P-CSA area loop pattern is robust and is reproduced in all three cases with only small differences. The results indicate that the horizontal loop pattern is primarily a product of mechanical conditions rather than any inherently different function of the muscle itself. Thus, the distinct phases of the loop can be explained solely based on mechanics.

Risk factors for clinical failure of peroral endoscopic myotomy in achalasia

The recent development of per oral endoscopic myotomy (POEM) has been a game changer in the management of patients with achalasia. However, approximately 1 in 10 patients will not experience clinical success. The aim of this mini-review is to describe the current state of knowledge about the risk factors associated with POEM failure for the treatment of achalasia. Suspected risk factors are detailed into pre-, intra-, and post-procedural factors and put into perspective. Pre-procedural factors have been described, such as pre-treatment Eckardt score, previous treatments for achalasia, sigmoid type esophagus, significant esophageal dilatation, non-type II achalasia, young age and long duration of symptoms. An intra-procedural factor, mucosal injury during POEM, has also been associated with POEM failure. The occurrence of post-POEM GERD was identified as a controversial post-procedural factor associated with failure. The presumed mechanisms of POEM failure are incomplete myotomy or ineffective LES disruption, as confirmed by high-resolution manometry. However, when manometry confirms a significant decrease in LES pressure, it is likely that either impaired peristalsis or a morphologic abnormality such as extreme esophageal dilatation or severe tortuosity, which are not treated by POEM, should be suspected. Notably, a recently described adverse effect of POEM is the formation of a pseudo-diverticulum at the site of the myotomy (blown out myotomy). We finally stress the importance of performing a complete workup in case of POEM failure as different mechanisms of POEM failure should lead to different management.