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OESO©2011
 
Volume: Barrett's Esophagus
Chapter: Pathophysiology
 

Does endoscopic evaluation of the flap valve predict reflux status?

L.D. Hill, R.A. Kozarek, C.E. Pope (Seattle)

Since its discovery in 1956, the lower esophageal sphincter (LES) has dominated discussions of the mechanisms of reflux [1]. Attempts have been made to raise LES pressure (LESP) in patients with reflux and to lower sphincter pressure in patients with achalasia. The observation that some patients with severe reflux had normal LESP was explained by the discovery of transient LES relaxations [2]. However, some individuals have been found with very low LESP and yet no reflux.

One explanation for this latter observation was offered by Hill et al. who studied reflux in cadavers [3]. They demonstrated a pressure gradient between stomach and esophagus by ligating the pylorus around a manometric/infusion catheter assembly and then infusing fluid until the fluid appeared in the esophagus. The pressure at which this occurred varied from 20 mm Hg to no demonstrable gradient with a mean gradient pressure of 12.2 mm Hg. Clearly this gradient could not have been caused by the muscle of the LES, and an anatomic cause was sought. It was noted that lower gradients existed in those cadavers who had an anatomic hiatus hernia, and that examination of the gastroesophageal junction (GEJ) from below through a gastrostomy showed a ridge of tissue around the GEJ which was not present in the cadavers with hiatus hernias. This ridge was called the gastroesophageal flap valve.

Attempts were then made to see if there was a counterpart to this ridge in the living patient by examining the GEJ from below with a retroflexed gastroscope [3]. In a small number of control subjects without clinical or pH evidence of reflux, a prominent ridge of tissue seemed to grip the shaft of the endoscope (Figure 1). This appearance was given a grade of I. If the ridge was prominent, but tended to open and shut with respiration, it was termed Grade II. Patients with severe endoscopic esophagitis had essentially no ridge of tissue (Grade III, Figure 2) or a wide open GEJ with no ridge of tissue and the ability to see esophageal mucosa through a patulous opening (Grade IV).

A larger group of 16 control and 40 patients were then evaluated by this grading system. Observations between different observers agreed quite well; the major problem was telling the difference between Grade I and Grade II and between Grade III and Grade IV. Accordingly, Grades I and II were identified as "normal" and Grades III and IV as "abnormal". Table I shows the excellent agreement between the flap valve grade and the

Table I. Reflux status versus flap valve grade.

reflux status of the patients. In these same patients, the measurement of LESP did not correlate well at all with the presence or absence of reflux.

This experience has essentially been replicated by two other groups of investigators. Contractor et al. studied 138 patients, using essentially the same criteria listed above [4]. They also found that Grade III and IV flap valves were found in most patients with erosive esophagitis. They did note that 16 of these patients had a Grade III or IV valve without esophagitis.

Doctor DeMeester's group has reported their findings in 268 consecutive patients who were endoscoped because of the suspicion of gastroesophageal reflux [5]. He found more acid exposure and more endoscopic esophagitis with increasing grades of the flap valve. Not all patients with Grade III or IV valves had esophagitis and/or increased acid exposure.

Preliminary observations by our group have shown that patients with reflux symptoms and/or erosive esophagitis whose 24 hr pH studies show predominant upright reflux may have a Grade I or II valve when endoscoped in the standard way.

However, when these patients are placed in the sitting position with the endoscope still in place, the grading of the valve changes to a III or IV. There is no similar change when patients with combined supine and upright reflux on pH studies are asked to sit up during endoscopy.

Figure 1. Normal flap valve (Grade I/II). Note the prominent ridge of tissue that seems to grip the shaft of the endoscope.

Figure 2. Abnormal flap valve (Grade III/IV). The ridge of tissue seen in control patients is markedly reduced or absent; the endoscope is not tightly gripped. (See page XXII for colour figure.)

We wondered whether the flap of tissue seen at endoscopy was a result of a large-bore tube passing through the GEJ and throwing up a fold of tissue. This possibility is made less likely by observations made on four patients during a change of a PEG feeding tube. A small-bore endoscope was passed through the gastrostomy tract and the GEJ observed without a tube passing through it. Although not as prominent, the fold of tissue is still present.

Observations of the flap valve after antireflux surgery can also be useful. After either a Nissen or a Hill fundoplication, there is restoration of a Grade I flap valve. Occasionally, patients will still complain of substernal burning postoperatively. If their flap valve appears normal, subsequent pH studies will usually not demonstrate reflux and another cause for the burning must be sought. Patients who complain of postoperative dysphagia which persists over three months will often show a twisted appearance to their flap valve. In our experience, this appearance predicts failure of dilatation to relieve the dysphagia and points to the need to restore a normal valve by reoperation.

The definition of the flap valve affords an anatomic correlation to help explain the mechanism(s) of reflux; it has even entered Grays Anatomy! It is difficult to predict what the relative contribution to the maintenance of gastroesophageal competence is provided by the flap valve, the diaphragm and the LES. They presumably all work together in concert. However, we feel that the examination and grading of the flap valve during esophagogastro-duodenoscopy only takes an extra minute or so and provides valuable information to help sort out the reflux status of the patient. Moreover, sitting the patient up during endoscopy frequently shows loss of an otherwise normal appearing valve in patients with predominant upright reflux.

References

1. Dent J. Patterns of lower esophageal sphincter function associated with gastroesophageal reflux. Am J Med 1997;103:23S-28S.

2. Mittal RK, Holloway RH, Penagini R, Blackshaw LA, Dent J. Transient lower esophageal sphincter relaxation. Gastroenterology 1995;109:601-610.

3. Hill LD, Kozarek RA, Kraemer SJM, Aye RW, Mercer CD, Low DE, Pope II CE. The gastroesophageal flap valve: in vitro and in vivo observations. Gastrointest Endosc 1996;44:541-547.

4. Contractor QQ, Akhtar SS, Contractor TQ. Endoscopic esophagitis and gastroesophageal flap valve. J Clin Gastroenterol 1999;28:233-237.

5. Oberg S, Peters JH, DeMeester TR, Lord RV, Johannson J, Crookes PF, Bremner CG. Endoscopic grading of the gastroesophageal valve in patients with symptoms of gastroesophageal reflux disease (GERD). Surg Endosc 1999;13:1184-1188.


Publication date: August 2003 OESO©2011