Evaluation of Esophageal Motor Function With High-resolution Manometry

Abstract

For several decades esophageal manometry has been the test of choice to evaluate disorders of esophageal motor function. The recent introduction of high-resolution manometry for the study of esophageal motor function simplified performance of esophageal manometry, and revealed previously unidentified patterns of normal and abnormal esophageal motor function. Presentation of pressure data as color contour plots or esophageal pressure topography led to the development of new tools for analyzing and classifying esophageal motor patterns. The current standard and still developing approach to do this is the Chicago classification. While this methodical approach is improving our diagnosis of esophageal motor disorders, it currently does not address all motor abnormalities. We will explore the Chicago classification and disorders that it does not address.

Keywords: Esophageal motility disorders; Esophagus; Manometry.

Conflict of interest statement

Conflicts of interest: Consultant for Given Imaging.

Figures

Figure 1

Comparing conventional recordings of manometric pressure with the Clouse plot or esophageal pressure topography (EPT). Conventional manometry tracings came from catheters made with pressure sensors spaced at relatively widely intervals, usually at 3- to 5-cm. The recording on the left (A) was made with a high-resolution manometry catheter and recording system, but it is displayed in the line mode so it looks like a conventional esophageal manometry recording. Seven of 36 recording channels were chosen for display to mimic what is seen with conventional manometry systems. Channels were selected to record simultaneously from the pharynx to the stomach. With old conventional manometry systems we could not simultaneously view pressures generated by the entire esophagus, including its sphincters. Notice that pressure is on the y-axis and time is on the x-axis. The numbers on the left indicate sensor location from the nares. EGJ indicates the esophagogastric junction, and WS indicates the timing of a wet swallow. The figure to the right (B) is esophageal motor activity from the same wet swallow displayed in the color contour mode. In this mode, pressure is represented by color (color bar on the right), sensor location is on the y-axis, and time is on the x-axis. Resting upper esophageal sphincter (UES) and lower esophageal sphincter (LES) pressures are seen horizontal bands of color that are several centimeters wide. Their hues indicate pressures that are greater than in the adjacent pharynx, esophagus, or stomach. Opening of the UES and LES relaxation are depicted as changes of color to hues that represent a lower pressure. A diagonal band of color running from the UES to the LES represents the peristaltic pressure wave. Variations in peristaltic pressure are produced by overlapping esophageal contractile segments: S1 is the striated muscle esophagus, S2 and 3 are the proximal and distal smooth muscle esophagus, respectively, and S4 is the LES repositioning itself at its resting position. There is a pressure trough between S1 and S2 that is called the transition zone, because it is the region over which the esophageal musculature transitions from striated to smooth muscle. Pressure in the swallowed bolus (intrabolus pressure) is represented by a small simultaneous rise in intraesophageal pressure seen as a simultaneous change to a lighter blue color (arrowhead). Notice that when the peristaltic wave passes the color becomes a darker blue indicating bolus clearance. TZ, transition zone.

Figure 2

The esophagogastric junction at rest. Pressures recorded from the esophagogastric junction (EGJ) are a composite of tonic lower esophageal sphincter (LES) contraction (**) and cyclical crural diaphragm contraction with inspiration (*). During inspiration pressure decreases in the thoracic cavity, and during expiration it increases. The opposite is true in the abdominal cavity. The point at which pressure across the EGJ during inspiration becomes negative relative to intraabdominal pressure is called the respiratory or pressure inversion point (PIP). It indicates the location of the crural diaphragm. The red arrowhead denotes the location of the PIP. The top panel is an example of a normal (Type I) EGJ in which the LES and crural diaphragm are coincident. In the middle panel there is a small spatial separation ( 2 cm) between the crural diaphragm and LES, indicating the presence of a large hiatal hernia (Type III EGJ). I, inspiration; E, expiration.

Figure 3

Evaluation of esophagogastric junction (EGJ) function during swallowing. The top panel is an esophageal pressure topography (EPT) of normal EGJ function following a wet swallow. As you can see pressure at the EGJ normally drops ahead of the advancing peristaltic pressure wave. It is not a direct measure of lower esophageal sphincter (LES) relaxation, but pressure in the swallowed bolus as it opens and traverses the EGJ. Esophagogastric junction function during swallowing is determined by a measurement called the 4-second integrated relaxation (residual) pressure (IRP). It is determined within a "deglutitive relaxation window," a window that straddles the EGJ and stretches for 10 seconds after opening of the upper esophageal sphincter (UES) (black brackets). This is the spatial and temporal domain within which EGJ function is evaluated. A tool called the eSleeve™ is used to set the spatial extent of the window, which is 6 cm in length by default. The eSleeve determines the highest pressure within the deglutitve relaxation window at each point in time. The 4-second IRP algorithm takes these pressures and averages the lowest of them over four continuous or discontinuous seconds (white boxes). This discontinuous measurement avoids inclusion of elevated pressures produced by contraction of the crural diaphragm (*) or cardiovascular structures in the calculation of IRP. The lower panel is an example of an abnormal IRP seen in achalasia. In this case, pressure at the EGJ results from failed LES relaxation and pressurization of the swallowed bolus above the LES (**).

Figure 4

Contraction front velocity (CFV) and distal latency are tools used to evaluate propagation of esophageal pressure waves. This figure depicts normal function of the esophagus and its sphincters. The black line is a 30 mmHg isobaric contour line. It identifies all loci in the esophageal pressure topography (EPT) where the pressure is 30 mmHg. The red circle filled with blue indicates the contractile deceleration point (CDP), which is the time point during a peristaltic pressure wave when peristalsis in the distal esophagus appears to slow appreciably. Functionally the CDP is the time at which esophageal peristalsis terminates, and the lower esophageal sphincter descends to its resting position in association with emptying of the phrenic ampulla. The CFV, which is a measure of peristaltic velocity in the smooth muscle esophagus, is obtained by calculating velocity from a best linear fit along the 30 mmHg contour line at the leading edge of the peristaltic pressure wave from transition zone to CDP (black dashed line). The other measure of propagation is the distal latency. It is the time from opening of the upper esophageal sphincter during swallowing (dashed white line) to the CDP. DL, distal latency; UES, upper esophageal sphincter; EGJ, esophagogastric junction.

Figure 5

Weak peristalsis is like ineffective esophageal motor function described by conventional manometry. The black line is the 20 mmHg isobaric pressure line. Weak peristalsis is characterized by gaps in the 20 mmHg isobaric pressure contour in the smooth muscle esophagus, or a wide transition zone. UES, upper esophageal sphincter.

Figure 6

Esophagogastric junction (EGJ) outflow obstruction is characterized by failed or incomplete opening of the EGJ (integrated relaxation or residual pressure [IRP] greater than normal), some peristalsis in the smooth muscle esophagus and pressurization of the swallowed bolus between an unyielding EGJ and peristaltic contraction (arrowhead). Peristalsis can be normal, weak, hypertensive or hypercontractile. UES, upper esophageal sphincter.

Figure 7

The distal contractile integral (DCI) is a measure of how robust peristalsis is in the smooth muscle esophagus. It is determined by first making a box that encompasses all swallow induced motor activity produced by contractile segments S2 and S3 (yellow dashed line). Next, the 20 mmHg isobaric contour line is determined (black line). The DCI is calculated by summing pressures from all of the time/length foci within the field constrained by the box and 20 mmHg isobaric contour line. UES, upper esophageal sphincter; EGJ, esophagogastric junction.

Figure 8

Achalasia is defined by failure of normal peristalsis and an inadequate lower esophageal sphincter relaxation (integrated relaxation or residual pressure [IRP] greater than normal). The disorder is further subclassified based upon the morphology of esophageal pressure patterns. Type I is characterized by little if any discernable pressure activity in the esophagus, type II by panesophageal pressurization and type III by premature esophageal contraction (short distal latency). Transient opening of the UES seen in the middle panel (*) is commonly seen in patients with achalasia and in other esophageal disorders that inhibit bolus clearance. It is not a swallow because no pharyngeal peristalsis is seen in conjunction with it. Instead it represents a venting mechanism.

Figure 9

The Chicago classification. IRP, integrated relaxation or residual pressure; DCI, distal contractile integral; DL, distal latency; CFV, contraction front velocity; IBC, isobaric contour.

Figure 10

Evaluation of peristalsis with the distal latency and contraction front velocity. (A) Distal esophageal spasm is characterized by normal lower esophageal sphincter relaxation and a short distal latency ( 9 cm/sec), normal distal latency (> 4.5 seconds) and normal integrated relaxation or residual pressure. The peristaltic pressure wave also meets criteria for weak peristalsis; that is, a wide gap at the transition zone produced by failure of peristalsis in the proximal smooth muscle esophagus. This might be the genesis of the measured rapid wave front velocity. Finally, the black arrow indicates a diaphragmatic contraction, so there is a large hiatal hernia. DL, distal latency; UES, upper esophageal sphincter; EGJ, esophagogastric junction; CFV, contraction front velocity; LES, lower esophageal sphincter.

Figure 11

The jackhammer esophagus is characterized by a distal contractile integral of > 8,000 mmHg · cm · sec, with normal propagation of the peristaltic wave front (distal latency > 4.5 seconds) and normal integrated relaxation or residual pressure. In the past it was considered part of the spectrum of nutcracker esophagus. DCI, distal contractile integral; DL, distal latency; UES, upper esophageal sphincter; EGJ, esophagogastric junction.

Figure 12

Pharyngeal pressurization. This is a topographical plot of pharyngeal motor function produced by a 5 mL water swallow. The asterisk indicates velopalatine closure. Above this is the nasopharynx. Between it and the upper esophageal sphincter (UES) is the mesopharynx. Pharyngeal peristalsis is seen as the pressure wave propagating from the end of velopalatine closure to the UES. Normally, during swallow-induced opening of the UES pharyngeal bolus pressure approximates that in esophageal bolus. In this case there is an elevated pharyngeal bolus pressure (arrowhead). This finding raises the possibility of pharyngeal outlet obstruction by a cricopharyngeal bar.

Figure 13

Transient lower esophageal sphincter (LES) relaxation is characterized manometrically by prolonged LES relaxation in the absence of a swallow, shortening of the esophagus (*), inhibition of crural diaphragm motor activity produced by respiration and equalization of the pressure across the esophagogastric junction upon its opening. Often there is opening of the upper esophageal sphincter to produce a belch, but not in this case. Ending of the transient LES relaxation is heralded by esophageal contraction, and the LES descends to its resting position. UES, upper esophageal sphincter; EGJ, esophagogastric junction.

Figure 14

Rumination is characterized manometrically by a valsalvainduced increase in intragastric pressure (*), relaxation of the upper esophageal sphincter and retrograde movement of a pressure wave from the stomach up the esophagus (dashed arrow). In this case, a swallow follows the event. After performing a standard high-resolution manometry, the patient ate a meal he felt would produce symptoms. He was instructed to identify regurgitation events by pressing the gag/choke marker on the monitor screen, and was left with the catheter in place for 30 minutes. Here he marked a rumination event. UES, upper esophageal sphincter; EGJ, esophagogastric junction.

Figure 15

Supragastric belching is striking to observe, with the patient repetitively forcing air into the esophagus and then expelling it immediately. This single supragastric belch is identified manometrically as opening of the upper esophageal sphincter and simultaneous increase of pressure at the esophagogastric junction produced by diaphragmatic contraction (arrowheads). The associated lowering of intrathoracic pressure (*) allows entry of air into the esophagus, but does not allow it to enter the stomach. This is followed immediately by a pressure wave in the esophagus (**) that is associated with expulsion of gas. Once initiated the patient may repeat this behavior for some time. UES, upper esophageal sphincter; EGJ, esophagogastric junction.