Guoxiang Shi

Increased frequency of transient lower esophageal sphincter relaxation induced by gastric distention in reflux patients with hiatal hernia

BACKGROUND & AIMS This study aimed to determine if hiatal hernia influences vulnerability to reflux and transient lower esophageal sphincter relaxation (tLESR) during gastric distention in patients with gastroesophageal reflux disease (GERD). METHODS Eight normal subjects and 15 patients with GERD were studied. A metal clip attached to the squamocolumnar junction (SCJ) was beneath the hiatus in all control subjects. Eight GERD patients with >/=1-cm SCJ-hiatus separation were considered hernia patients, and 7 with <1-cm separation were considered nonhernia patients. Manometry and esophageal pH were recorded for 30 minutes, after which the stomach was loaded with acid dextrose and the recording continued for 2 hours with intragastric air infusion of 15 mL/min. RESULTS Baseline reflux was comparable among groups. Gastric distention increased the frequency of reflux by the tLESR mechanism in all groups. Controls and nonhernia patients had median increases of 4.0 and 4.5 in tLESR frequency, respectively, and hernia patients had a median increase of 9.5/h. tLESR frequency was highly correlated with the SCJ-hiatus separation (r = 0.76; P < 0.001). CONCLUSIONS Gastric air infusion was a potent stimulus for tLESR and reflux. The resultant tLESR frequency was directly proportional to the separation between the SCJ and hiatus, suggesting that the perturbed anatomy associated with hiatal hernia predisposed to eliciting tLESRs in patients with GERD.

Esophagogastric junction opening during relaxation distinguishes nonhernia reflux patients, hernia patients, and normal subjects

BACKGROUND AND AIMS Flow across the esophagogastric junction (EGJ) is strongly related to opening dimensions. This study aimed to determine whether opening of the relaxed EGJ was altered in patients with gastroesophageal reflux disease (GERD). METHODS Seven normal subjects (NL), 9 GERD patients without hiatus hernia (NHH), and 7 with hiatus hernia (HH) were studied. Cross-sectional area (CSA) of the relaxed EGJ was measured during low-pressure distention using a modified barostat technique that resulted in filling a compliant bag straddling the EGJ with renograffin to the set pressure. Swallows were imaged fluoroscopically at distensive pressures of 2-12 mm Hg. The diameter of the narrowest point of the EGJ in PA and lateral projections was measured from digitized images. CSA was determined as a function of intrabag pressure. RESULTS The minimal EGJ opening aperture occurred at the diaphragmatic hiatus in all subjects. At pressures </=0 mm Hg, EGJ opening was observed only in HH patients, making it plausible for these patients to reflux during deglutitive relaxation. At pressures >0 mm Hg, there were significant increases in EGJ CSA both for HH and NHH compared with NL (P < 0.001) and for HH compared with NHH (P < 0.005). This difference may explain the diminished air/water discrimination seen during transient lower esophageal sphincter (LES) relaxation-associated reflux in GERD patients. CONCLUSIONS Anatomic degradation of the EGJ distinguishes GERD patients from normal subjects, and these changes may impact on both the observed mechanisms of reflux and the constituents of reflux during transient LES relaxation. Therapy focused on EGJ compliance may benefit GERD patients.

Esophageal solid bolus transit: studies using concurrent videofluoroscopy and manometry

ObjectiveOur aim was to assess the efficacy and mechanism of solid bolus transit through the esophagus.MethodsEight healthy volunteers were studied with concurrent manometry and videofluoroscopy while swallowing 5 ml liquid barium, a 5–6 mm diameter bread ball, and 4 g chewed bread in both a supine and upright posture. As many as four successive swallows were performed until clearance was achieved.ResultsThe esophageal clearance of liquid barium was 100% with the first swallow. Clearance of the unchewed bread ball occurred with the first swallow in only 6.7% of trials in the upright posture and 5.9% in the supine posture. After four swallows, clearance was 100% and 52.9% in the upright and supine postures, respectively. Chewed bread was more readily cleared than unchewed bread, with 100% clearance after two swallows in the upright posture and 91% clearance after four swallows in the supine posture. The most common locus of bread stasis was at the aortic arch and carina. The bread boluses were noted to move more effectively when localized in the head as opposed to the tail of the bolus composite. Nonocclusive contractions often occurred at the bolus tail despite the increased peristaltic amplitude seen with the chewed bread. Failed peristalsis, a frequent cause for solid clearance failure, was observed during 30% of all bread swallows. This usually occurred distal to the stopping point of the bolus, suggesting it to be the result rather than the cause of impaired transit.ConclusionsAlthough infrequently perceived by these normal subjects and in contradistinction to liquid clearance, bread is rarely cleared from the esophagus with a single swallow. Mastication and an upright posture facilitate the esophageal transport of solids. Bolus composition and impaired bolus transit alter the amplitude and conductance of peristalsis. Manometric data pertaining to liquid clearance through the esophagus do not readily apply to bread.

Restoration of normal distensive characteristics of the esophagogastric junction after fundoplication.

Objective:To study the mechanical characteristics of the esophagogastric junction (EGJ) of postfundoplication patients and compare them with previously reported data on normal subjects and GERD patients. Methods:Eight normal subjects, 9 GERD patients, and 8 fundoplication patients were studied with concurrent manometry, fluoroscopy, and stepwise controlled barostat distention of the EGJ. The minimal barostat pressure required to open the EGJ during the interswallow period was determined. Thereafter, barium swallows were imaged in 5-mm Hg increments of intrabag pressure. EGJ diameter and length were measured at each pressure during deglutitive relaxation. Results:EGJ opening diameter during deglutitive relaxation was on average 0.5 cm greater in GERD patients compared with normal subjects and fundoplication patients (P < 0.05). EGJ opening pressure and opening diameter were comparable between normal subjects and fundoplication patients; however, the EGJ length was 32% longer in fundoplication patients. Conclusions:Fundoplication restores distensibility of the EGJ to a level similar to normal subjects. Since trans-EGJ flow is related to EGJ length and EGJ diameter, these findings suggest that retrograde flow through the EGJ would be decreased by both a reduction in diameter and an increase in length of the EGJ.

Why do we hiccup

See article on page 590 Considering the fact that almost everyone experiences hiccups at one time or another, remarkably little is known about them. The name itself is onomatopoeic, which is appropriate considering that the only common understanding of the hiccup is of the characteristic sound. Hiccups can be predictably elicited in some individuals by overindulgence of food, alcohol, or both, sometimes providing evidence of such behaviour and making them a common object of humour. There are, however, instances in which hiccups become intractable (singultus) causing insomnia, wasting, exhaustion, and even death, prompting scientific scrutiny of this otherwise harmless curiosity.1In this issue Fass et al (see page 590) present original investigative work on the afferent limb of the hiccup reflex. Fass et al used a barostat to characterise the parameters of oesophageal distention that could elicit hiccups in normal volunteers. They report that rapid phasic distension of the proximal, but not distal, oesophagus could reproducibly induce hiccups in four of 10 subjects. Hiccups occurred during rapid inflation of the barostat bag and immediately resolved with deflation, strongly implicating oesophageal mechanoreceptors as the critical …

Distinct patterns of oesophageal shortening during primary peristalsis, secondary peristalsis and transient lower oesophageal sphincter relaxation

Abstract  This study characterized oesophageal shortening during secondary peristalsis and transient lower oesophageal sphincter relaxation (TLOSR) in an attempt to determine its contribution to the opening mechanism. Eight healthy subjects (four males, 26 ± 1 years) had metal clips affixed at 0, +3, and +8 cm relative to the squamocolumnar junction (SCJ), defining two distal oesophageal segments. Axial clip movement was assessed with concurrent videofluoroscopy and manometry during primary peristalsis, secondary peristalsis and TLOSR. Clip‐defined oesophageal segment length change was measured at 0.5‐s intervals. The magnitude of the most distal segment shortening was least with TLOSR, greatest with primary peristalsis and intermediate with secondary peristalsis. Conversely, maximal overall oesophageal shortening during TLOSR, evidenced by SCJ movement, was similar to that during primary peristalsis. In 3/12 TLOSRs, the moment of LOS opening and gas reflux was optimally imaged; SCJ excursion was 0.3 ± 0.1 cm prior to LOS opening and 1.4 ± 0.7 cm immediately after gas reflux. The segmental pattern of oesophageal shortening was distinct during primary peristalsis, secondary peristalsis and TLOSR. During TLOSR, significant elevation of the SCJ occurred only after LOS opening, suggesting that this was a consequence of oesophageal distension induced by gas reflux rather than a component of the opening mechanism.

Lower esophageal sphincter relaxation characteristics using a sleeve sensor in clinical manometry

Objective:We undertook this study to determine the characteristics of swallow-induced lower esophageal sphincter (LES) relaxation in the setting of clinical manometry using a standardized methodology.Methods:We reviewed 170 manometric recordings performed using a perfused manometric assembly with a sleeve sensor and a computer polygraph. Patients were categorized as patient controls, gastroesophageal reflux disease (GERD), diffuse esophageal spasm (DES), or achalasia. Tracing were semiautomatically analyzed for basal LES pressure, LES pressure during deglutitive relaxation (relaxation LES pressure), duration of LES relaxation, timing of LES relaxation, and the success rate of primary peristalsis.Results:Forty-six patient controls, 93 with GERD, five with DES, and 26 with achalasia were identified. GERD and achalasia patients had lower or higher basal LES pressures than patient controls, respectively. Compared with patient controls, achalasia patients had higher relaxation LES pressures, lower percent LES relaxation, and shorter durations of LES relaxation. The best single measure for distinguishing achalasia was the relaxation LES pressure; using the 95th percentile value of patient controls (12 mm Hg) as the upper limit of normal, its sensitivity and positive predictive value for the diagnosis of achalasia were 92% and 88%, respectively. Coupled with the finding of aperistalsis, a relaxation LES pressure ≥10 mm Hg achieved 100% sensitivity and positive predictive value among these patients.Conclusion:Sleeve sensor recording is a practical method for clinical manometry that reliably records LES relaxation characteristics and is amenable to both a standardized manometry protocol and a semiautomated analysis routine. Relaxation LES pressure has a high diagnostic value for achalasia.

Measuring EGJ opening patterns using high resolution intraluminal impedance

Abstract  The aim of this study was to adapt impedance methodology to study esophagogastric junction (EGJ) sphincter opening and compare opening patterns of the EGJ during deglutitive LES relaxation (dLESR) and transient LES relaxation (tLESR). We studied eight healthy subjects with a novel 12‐lumen combined impedance/manometry catheter, the main element of which was a 6 cm sleeve sensor with six side hole sensors and six impedance rings spaced at 1 cm increments along its length. Subjects underwent an air infusion protocol after standard assessment and data tracings and isocontour plots were analysed to assess opening characteristics of the EGJ during dLESRs and tLESRs. Our results revealed that during dLESR the opening pattern was top to bottom, occurred in 0–2.7 s and in 29 of 35 (83%) cases the leading edge of the bolus was liquid. Opening during tLESR began between −7.8 and +8.6 s relative to the onset of nadir LES relaxation. The opening pattern during tLESR was bottom to top, occurred in 0–7.7 s, and in 22 of 29 (76%) the leading edge was liquid. These results support that impedance monitoring can be adapted to identify sphincter opening, to distinguish sphincter opening from sphincter relaxation, and to determine luminal contents during the opening period.

Manometric characteristics of the upper esophageal sphincter recorded with a microsleeve

OBJECTIVES:We compared manometric recordings of the upper esophageal sphincter (UES) recorded with a miniature sleeve to those obtained using standard manometry.METHODS:The UES pressure of eight volunteer subjects was measured by station pull-through (SPT), by rapid pull-through (RPT), and with a microsleeve sensor for 30 min, followed by 15 min of esophageal acid infusion. Deglutitive UES relaxation recorded with a microsleeve and solid state sensor were compared.RESULTS:The UES pressure recorded with the microsleeve (25 ± 9 mm Hg) was significantly less than that by SPT (114 ± 18 mm Hg) or RPT (152 ± 19 mm Hg), and was unaffected by acid infusion. Periods of low UES pressure were observed during long interswallow intervals (11 ± 4, range 6–18 mm Hg). Deglutitive relaxation duration and intrabolus pressure measured with the microsleeve were less than those recorded by the solid state transducer.CONCLUSIONS:“Normal” UES pressure is heavily dependent on measurement technique; pressures obtained with a miniature sleeve are a fraction of those obtained by SPT or RPT. During periods of relative comfort with minimal swallowing, UES tone is approximately 10 mm Hg, similar to that during sleep. Volume modulation of deglutitive UES relaxation is demonstrable with a microsleeve, albeit with less precision than with a solid-state transducer.

The effect of glucagon-induced gastric relaxation on TLOSR frequency

Abstract This study aimed to determine the effect of glucagon‐induced gastric relaxation on the frequency of transient lower oesophageal sphincter relaxations (TLOSRs). Eight normal subjects (four male, age 18–52 y) were studied after a 6‐h fast using a combined manometric barostat assembly. The recording was divided into two 1‐h sessions: (1) a baseline period with the barostat set at minimal distending pressure (MDP) + 2 mmHg and (2) a period with continuous glucagon or placebo infusion with barostat set at MDP + 2 mmHg. Patients were studied on two different days and randomly received glucagon (4.8 μg kg−1 bolus followed by 9.6 μg kg−1 h−1 infusion) on 1 day and placebo (saline) on another. Lower oesophageal sphincter (LOS) pressure, frequency of TLOSRs, and barostat bag volumes were determined for both placebo and glucagon infusion. Glucagon induced significant fundal relaxation compared with placebo (P < 0.05) and significantly decreased baseline LEOS pressure (P < 0.05). The frequency of TLOSRs was not altered by glucagon infusion compared with placebo. Despite causing substantial proximal stomach relaxation, glucagon did not increase TLOSR frequency. This suggests that the relevant gastric mechanoreceptors responsible for triggering TLOSRs do not respond to passive elongation.