Neural regulation of tone in the oesophageal body: in vivo barostat assessment of volume-pressure relationships in the feline oesophagus

The Esophagogastric Anastomosis: The Importance of Anchoring Sutures in Reducing Anastomotic Leak Rates

Background

The incidence of anastomotic leakage in gastrointestinal surgery is highest after esophagogastric anastomosis, with leakage rates of 10% to 38% still being reported, but little consensus as to cause or corrective. The role of anastomotic tension from a series of physiological forces acting on the anastomosis from the moment of recovery from anesthesia may be underestimated. It was hypothesized that anchoring the conduit in the mediastinum would provide the greatest protection during the vulnerable healing phase.

Patients and Methods

A prospectively maintained database was interrogated for anastomotic leakage following the introduction of an anastomotic technique employing anchoring sutures where the gastric conduit was secured to the mediastinal pleura with 3 obliquely inserted load-bearing sutures. A contrast study was performed between days 5 and 7 and all intrahospital mortalities underwent autopsy. Clinical, radiological, and autopsy leaks were recorded.

Results

Of 146 intrathoracic esophagogastric anastomoses in 144 patients, 81 (55%) of which were stapled, there was 1 clinical leak and 1 patient with an aortoenteric fistula, considered at autopsy to be possibly due to an anastomotic leak, to give an anastomotic leak rate of 2 in 146 (1.37%).

Conclusion

The low anastomotic leak rate in this series is potentially due to the protective effect of anchoring sutures, the chief difference from an otherwise standard anastomotic technique. These sutures protect the anastomosis from a series of distracting forces during the most vulnerable phase of healing. It is intuitive that the absence of tension would also reduce any risk posed by a minor impairment of blood supply or any imperfection of the technique.

Management and outcomes of 13 dogs treated with a modified Heller myotomy and Dor fundoplication for lower esophageal sphincter achalasia-like syndrome

OBJECTIVE

To report the management and outcomes of dogs treated for lower esophageal sphincter achalasia-like syndrome (LES-AS) with modified Heller myotomy, Dor fundoplication, and with the use of a temporary gastrostomy tube.

STUDY DESIGN

Retrospective.

SAMPLE POPULATION

Thirteen client-owned dogs.

METHODS

Medical records and a client survey were used to assess frequency of vomiting/regurgitation, quality of life (QoL), bodyweight, and feeding modifications at the following time points: prior to referral, postoperatively from discharge to first recheck (4-6 weeks), and from first recheck to survey (48 months). Postoperative and gastrostomy tube complications were surveyed and recorded. Pretreatment and 4-6 weeks postoperative videofluoroscopic swallow studies (VFSS) were compared. Two-sided t-tests were used to compare outcomes between survey time points.

RESULTS

Postoperative VFSS scores (available in 9 dogs) improved over preoperative scores in 6 dogs, and 12/13 dogs survived to discharge. One dog was euthanized 3 days postoperatively due to aspiration pneumonia. Postoperative gastrostomy tube complications occurred in half of the dogs that survived to discharge. According to the owners, scores assigned to vomiting/regurgitation improved by 180% (P = .004), QoL by 100% (P = .004), and bodyweight by 63% (P = .035).

CONCLUSION

Modified Heller myotomy with Dor fundoplication and the use of a temporary gastrostomy tube improved clinical signs and owners' perceived quality of life in half of the dogs treated for LES-AS in our clinical setting. Oral sildenafil therapy discontinued postoperatively suggests that surgery was equally efficacious.

CLINICAL SIGNIFICANCE

Modified Heller myotomy with Dor fundoplication and temporary gastrostomy tube is a treatment option with potentially sustained benefits for dogs that have LES-AS.

Ineffective esophageal motility: Concepts, future directions, and conclusions from the Stanford 2018 symposium

BACKGROUND

Ineffective esophageal motility (IEM) is a heterogenous minor motility disorder diagnosed when ≥50% ineffective peristaltic sequences (distal contractile integral <450 mm Hg cm s) coexist with normal lower esophageal sphincter relaxation (integrated relaxation pressure < upper limit of normal) on esophageal high-resolution manometry (HRM). Ineffective esophageal motility is not consistently related to disease states or symptoms and may be seen in asymptomatic healthy individuals.

PURPOSE

A 1-day symposium of esophageal experts reviewed existing literature on IEM, and this review represents the conclusions from the symposium. Severe IEM (>70% ineffective sequences) is associated with higher esophageal reflux burden, particularly while supine, but milder variants do not progress over time or consistently impact quality of life. Ineffective esophageal motility can be further characterized using provocative maneuvers during HRM, especially multiple rapid swallows, where augmentation of smooth muscle contraction defines contraction reserve. The presence of contraction reserve may predict better prognosis, lesser reflux burden and confidence in a standard fundoplication for surgical management of reflux. Other provocative maneuvers (solid swallows, standardized test meal, rapid drink challenge) are useful to characterize bolus transit in IEM. No effective pharmacotherapy exists, and current managements target symptoms and concurrent reflux. Novel testing modalities (baseline and mucosal impedance, functional lumen imaging probe) show promise in elucidating pathophysiology and stratifying IEM phenotypes. Specific prokinetic agents targeting esophageal smooth muscle need to be developed for precision management.

Evaluation of Esophageal Contraction Reserve Using HRM in Symptomatic Esophageal Disease

Esophageal high resolution manometry (HRM) is the gold standard for assessment of esophageal motor disorders, but motor responses to the standard 5 mL water swallow protocol may not provide precision in defining minor motor disorders. Provocative maneuvers, particularly multiple rapid swallows (MRS), have been used to assess deglutitive inhibition during the repetitive swallows, and the contractile response following the final swallow of the sequence. The augmentation of esophageal smooth muscle contraction following MRS is termed contraction reserve. This is determined as the ratio between esophageal body contraction vigor (distal contractile integral, DCI) following MRS to the mean DCI after single swallows, which is ≥1 in the presence of contraction reserve. Reliable assessment of contraction reserve requires the performance of 3 MRS maneuvers during HRM. Absence of contraction reserve is associated with a higher likelihood of late postfundoplication dysphagia and may correlate with higher esophageal reflux burden on ambulatory reflux monitoring. Esophageal motor responses to abdominal compression, functional lumen imaging probe (FLIP) balloon distension, and pharmacologic testing (using edrophonium and cisapride) may correlate with contraction reserve. Other provocative tests useful during HRM include rapid drink challenge, solid and viscous swallows, and standardized test meals, which are more useful in evaluation of esophageal outflow obstruction and dysphagia syndromes than in identification of contraction reserve. Provocative maneuvers have been recommended as part of routine HRM protocols, and while useful clinical information can be gleaned from these maneuvers, further research is necessary to determine the precise role of provocative testing in clinical esophagology.

Sildenafil improves clinical signs and radiographic features in dogs with congenital idiopathic megaoesophagus: a randomised controlled trial

We evaluated the efficacy of oral sildenafil citrate in dogs with congenital idiopathic megaoesophagus (CIM). Twenty-one puppies were randomly assigned to two groups (treatment and control). The dogs were given sildenafil oral suspension 1 mg/kg every 12 hours for 14 days or placebo in a masked fashion. Clinical signs (frequency of regurgitation and weight gain) and oesophagrams (relative oesophageal diameter, ROD) were evaluated in order to assess the efficacy of drug treatment, by examiners who were unaware of the study protocol. In addition, a set of in vitro experiments on isolated samples of canine lower oesophageal sphincter (LOS) was performed, and the effects of increasing concentrations of sildenafil on basal tone and electrically-stimulated motility were assessed. Sildenafil administration significantly reduced the number of regurgitation episodes (0.88±1.40 v 2.65±1.56, P<0.0001) and significantly increased weight gain in the treated dogs compared to controls (79.76±28.30 per cent v 53.40±19.30 per cent, P=0.034). ROD values, at the end of the treatment period, were significantly decreased in the sildenafil group, compared to pre-treatment values (0.97±0.19 v 0.24±0.14, P<0.0001), in contrast to control subjects (0.98±0.17 v 1.10±0.25, P=0.480). In accordance with the in vivo findings, sildenafil dose-dependently reduced basal tone and increased electrically-induced relaxation of dog LOS samples. These results suggest that sildenafil citrate helps ameliorate clinical and radiographic signs in dogs with CIM by reducing LOS tone, and could represent a novel therapeutic tool for the treatment of this disease.

Diabetes-induced mechanophysiological changes in the esophagus

Esophageal disorders are common in diabetes mellitus (DM) patients. DM induces mechanostructural remodeling in the esophagus of humans and animal models. The remodeling is related to esophageal sensorimotor abnormalities and to symptoms frequently encountered by DM patients. For example, gastroesophageal reflux disease (GERD) is a common disorder associated with DM. This review addresses diabetic remodeling of esophageal properties and function in light of the Esophagiome, a scientifically based modeling effort to describe the physiological dynamics of the normal, intact esophagus built upon interdisciplinary approaches with applications for esophageal disease. Unraveling the structural, biomechanical, and sensory remodeling of the esophagus in DM must be based on a multidisciplinary approach that can bridge the knowledge from a variety of scientific disciplines. The first focus of this review is DM-induced morphodynamic and biomechanical remodeling in the esophagus. Second, we review the sensorimotor dysfunction in DM and how it relates to esophageal remodeling. Finally, we discuss the clinical consequences of DM-induced esophageal remodeling, especially in relation to GERD. The ultimate aim is to increase the understanding of DM-induced remodeling of esophageal structure and sensorimotor function in order to assist clinicians to better understand the esophageal disorders induced by DM and to develop better treatments for those patients.

Anatomy and physiology of the esophageal body

The primary role of the esophagus is to propel swallowed food or fluid into the stomach and to prevent or clear gastroesophageal reflux. This function is achieved by an organized pattern that involves a sensory pathway, neural reflexes, and a motor response that includes esophageal tone, peristalsis, and shortening. The motor function of the esophagus is controlled by highly complex voluntary and involuntary mechanisms. There are three different functional areas in the esophagus: the upper esophageal sphincter, the esophageal body, and the LES. This article focused on anatomy and physiology of the esophageal body.

Neurotransmission in lower esophageal sphincter of W/Wv mutant mice

To address the controversy surrounding the role of interstitial cells of Cajal (ICC) in nitrergic neurotransmission to gastrointestinal smooth muscle, circular smooth muscle from the lower esophageal sphincter (LES) of W/W(v) wild-type and mutant (ICC-deficient) mice were studied by using intracellular and tension recordings in vitro. Resting membrane potential was more negative, and the spontaneous unitary potentials diminished in mutant mice. In wild-type mice, nerve stimulation induced a biphasic inhibitory junction potential (IJP) consisting of a fast initial IJP followed by a long-lasting slow IJP (LSIJP). The IJP was markedly impaired in a significant proportion of mutant mice, whereas in others it was normal. Pharmacological studies in the mice with markedly impaired IJPs revealed that cholinergic and purinergic components of the nerve-mediated responses appeared intact. In wild-type mice, caffeine hyperpolarized smooth muscle cells, inhibited the initial fast IJP, and completely abolished the LSIJP. In mutant mice, caffeine depolarized smooth muscle cells and abolished the impaired LSIJP but did not affect the initial fast IJP. Immunohistochemical staining for c-Kit confirmed deficiency of ICC in mutant mice with a normal nitrergic IJP. Rings of LES circular smooth muscle from W/W(v) mutant mice generated significantly less spontaneous tone than controls. When tone was restored with carbachol, normal nitrergic LES relaxation was recorded. These data suggest that 1) there is significant variability in the generation of nitrergic neurotransmission in the LES of W/W(v) mutant mice, whereas purinergic and cholinergic neurotransmission are intact; 2) the altered nitrergic responses appear to be associated with abnormal Ca2+-dependent signaling initiated by spontaneous Ca2+ release from sarcoplasmic reticulum in smooth muscle cells; and 3) c-Kit-positive ICC are not essential for nitrergic neurotransmission in mouse LES smooth muscle.

Deterioration of muscle function in the human esophagus with age

Most studies on the effect of aging on esophageal motor function have shown that peristaltic function deteriorates with age. Esophageal motor function is traditionally studied by means of manometry and radiography. Distension of the esophagus with evaluation of active and passive mechanical parameters have become available during recent years. In this study, we did a manometric swallow analysis and used the distension method to study esophageal properties and function during aging. An impedance planimetric probe with a bag for distension was placed in the distal esophagus of 25 healthy volunteers with a median age of 35 (range 23-86) years. Distensions were done at an infusion rate of 25 ml min(-1) with and without relaxation of neuromuscular activity with butylscopolamine. The infusion was reversed when moderate pain was experienced by the subjects. Swallow-induced contraction amplitudes decreased as function of age for persons older than 40 years (P < 0.05). The total and passive tension showed an exponential increase as function of the change in radius, whereas the active tension increased until it reached a local maximum point. The maximum active tension deteriorated as a function of age after the age of 40 years (P < 0.05). Furthermore, esophagus became stiffer with age. In conclusion, age-related changes of increased stiffness and reduced primary and secondary peristalsis were found in the human esophagus with a deterioration of esophageal function after the age of 40 years. Such changes may contribute to the high prevalence of reflux disease in elderly.

Response of the esophageal body to wet and dry swallows in Chagas' disease

BACKGROUND: Wet swallows cause a greater esophageal contraction amplitude and duration than dry swallows. In Chagas' disease there is a reduction in amplitude of esophageal contraction but we do not know if the difference between wet and dry swallows is seen in the disease. AIM: To compare the esophageal contractions after wet and dry swallows in patients with Chagas' disease. METHODS: We measured the area under the curve (amplitude x duration) of the esophageal contractions in 30 patients with a diagnosis of esophageal involvement by Chagas' disease and 44 controls. We used the manometric method with continuous perfusion. The contractions were measured at 2, 7, 12 and 17 cm below the upper esophageal sphincter, after five swallows of a 5 mL bolus of water alternated with five dry swallows. RESULTS: In the control group wet swallows caused a higher area under the curve than dry swallows. There was no difference between wet and dry swallows in Chagas' disease patients, and there was no difference in wet and dry swallows in Chagas' disease patients compared with dry swallows of controls. At 12 and 17 cm from the upper esophageal sphincter the area under the curve after wet and dry swallows in Chagas' disease patients younger than 60 years (n = 15) was higher than in Chagas' disease patients older than 60 years (n = 15). CONCLUSION: We conclude that in normal subjects there is adaptation to the presence of a liquid bolus inside the esophageal body, which does not happen in patients with Chagas' disease.

A novel partial 5HT3 agonist DDP733 after a standard refluxogenic meal reduces reflux events: a randomized, double-blind, placebo-controlled pharmacodynamic study

BACKGROUND

DDP733, a selective partial 5HT(3) receptor agonist, increases lower oesophageal sphincter pressure in experimental animal models. However, its effect on gastro-oesophageal reflux or lower oesophageal sphincter pressure in humans remains unknown.

AIM

To evaluate the effect of DDP733 on reflux episodes in healthy volunteers receiving a refluxogenic meal.

METHODS

A randomized, double-blind, placebo-controlled cross-over study evaluated the pharmacodynamic effects of DDP733 (0.5, 0.8 and 1.4 mg). Healthy subjects underwent oesophageal manometry and intra-oesophageal multichannel intraluminal impedance and pH after a refluxogenic meal.

RESULTS

DDP733 0.5 mg significantly (P = 0.013) reduced the rate of reflux episodes after a refluxogenic meal from 10 (+/-2.2) on placebo to 6 (+/-1.2) on drug over a 2-h period. DDP733 0.8 and 1.4 mg had no significant effect on reducing the number of reflux episodes. Significant differences in resting lower oesophageal sphincter pressure and the proportion of time pH was <4 (placebo minus drug) after a refluxogenic meal were not observed. No serious adverse events were reported.

CONCLUSION

In healthy subjects, the partial 5HT(3) agonist DDP733 at a dose of 0.5 mg significantly reduces the rate of reflux events, but did not result in a significant change in lower oesophageal sphincter pressure at 1 h postdosing.

Directional, regional, and layer variations of mechanical properties of esophageal tissue and its interpretation using a structure-based constitutive model

The esophagus, like other soft tissues, exhibits nonlinear and anisotropic mechanical properties. As a composite structure, the properties of the outer muscle and inner mucosal layer are different. It is expected that the complex mechanical properties will induce nonhomogeneous stress distributions in the wall and nonuniform tissue remodeling. Both are important factors which influence the function of mechanosensitive receptor located in various layers of the wall. Hence, the characterization of the mechanical properties is essential to understand the neuromuscular motion of the esophagus. In this study, the uniaxial tensile tests were conducted along two mutually orthogonal directions of porcine esophageal tissue to identify the directional (circumferential and axial), regional (abdominal, thoracic, and cervical), and layer (muscle and mucosa) variations of the mechanical properties. A structure-based constitutive model, which took the architectures of the tissue's microstructures into account, was applied to describe the mechanical behavior of the esophagus. Results showed that the constitutive model successfully described the mechanical behavior and provided robust estimates of the material parameters. In conclusion, the model was demonstrated to be a good descriptor of the mechanical properties of the esophagus and it was able to facilitate the directional, layer, and regional comparisons of the mechanical properties in terms of the associated material parameters.

New perspectives of studying gastrointestinal muscle function

The motor function of the gastrointestinal tract has primarily been studied using manometry and radiography, though more indirect tests have also been applied. Manometry and radiography do not provide detailed information about the muscle properties as can be assessed from studies of muscle properties in muscle strips in vitro. In recent years a technique based on impedance planimetric measurement of pressure-cross-sectional area relations in a distending bag has proven to provide more detailed information about the muscle function in vivo. This review shows examples of new muscle function analysis such as length-tension diagrams, force-velocity curves and preload-afterload diagrams.

New analysis for the study of the muscle function in the human oesophagus

The aim was to further develop a method for studying the active and passive tissue properties in the human oesophagus. An impedance planimetric probe with a bag for distension was placed in the distal oesophagus in 14 healthy volunteers. Distension was done at an infusion rate of 25 mL min(-1) with and without the administration of the antimuscarinic drug butylscopolamine. The flow was reversed when moderate pain was experienced by the subject. The total and the passive tension showed an exponential behaviour as function of the change in radius. The active tensions increased until they reached a maximum point. The active tension decreased after the maximum until the distension was stopped shortly after due to the pain. The change in tension during distension-induced contractions (the afterload) was plotted as function of the precontraction radius (the preload). The human oesophagus behaves in a manner known from in vitro studies on muscle strips and exhibits a muscle diagram similar to that in the heart, i.e. the larger the initial muscle length during distension (within limits), the greater the contraction force.

Gastrointestinal Function Regulation by Nitrergic Efferent Nerves

Gastrointestinal (GI) smooth muscle responses to stimulation of the nonadrenergic noncholinergic inhibitory nerves have been suggested to be mediated by polypeptides, ATP, or another unidentified neurotransmitter. The discovery of nitric-oxide (NO) synthase inhibitors greatly contributed to our understanding of mechanisms involved in these responses, leading to the novel hypothesis that NO, an inorganic, gaseous molecule, acts as an inhibitory neurotransmitter. The nerves whose transmitter function depends on the NO release are called "nitrergic", and such nerves are recognized to play major roles in the control of smooth muscle tone and motility and of fluid secretion in the GI tract. Endothelium-derived relaxing factor, discovered by Furchgott and Zawadzki, has been identified to be NO that is biosynthesized from l-arginine by the constitutive NO synthase in endothelial cells and neurons. NO as a mediator or transmitter activates soluble guanylyl cyclase and produces cyclic GMP in smooth muscle cells, resulting in relaxation of the vasculature. On the other hand, NO-induced GI smooth muscle relaxation is mediated, not only by cyclic GMP directly or indirectly via hyperpolarization, but also by cyclic GMP-independent mechanisms. Numerous cotransmitters and cross talk of autonomic efferent nerves make the neural control of GI functions complicated. However, the findingsrelated to the nitrergic innervation may provide us a new way of understanding GI tract physiology and pathophysiology and might result in the development of new therapies of GI diseases. This review article covers the discovery of nitrergic nerves, their functional roles, and pathological implications in the GI tract.

Effect of repeated cycles of acute esophagitis and healing on esophageal peristalsis, tone, and length

Severe esophagitis is associated with motor abnormalities in the esophageal body and lower esophageal sphincter. Reflux disease involves repeated episodes of mucosal inflammation and spontaneous or treatment-induced healing. The aims of this study were 1) to further assess changes induced by acute esophagitis on esophageal peristalsis, tone, and shortening and 2) to assess the effect of repeated sequences of acute esophagitis-healing on these motor parameters. Experiments were performed on adult cats. Esophageal manometry and barostat were performed before, 24 h after, and every 7 days after intraesophageal acid perfusion (0.1 N HCl, 80 min). Esophageal length was measured during manometry, and compliance of the esophageal body was assessed with barostat. The identical protocol was performed 8 and 16 wk after the first acid perfusion. The degree of esophageal mucosal damage was evaluated by endoscopy, histopathology, and myeloperoxidase activity. Acid perfusion induced severe esophagitis. At 24 h, distal peristaltic contractions disappeared, lower esophageal sphincter pressure was reduced by 60%, the esophagus length was 1-2 cm shorter, and esophageal compliance was reduced by 30%. Most parameters recovered in 4 wk. Subsequent repeated acute injuries induced similar endoscopic esophagitis but a different pattern of inflammatory infiltration and fibrosis in the mucosa and muscle layers, resulting in milder motor disturbances. Acute experimental esophagitis provokes severe but reversible hypomotility. Spaced repeated acute injuries provoke milder motor effects, suggesting an adaptive response.