Original article

Cardiomyotomy in achalasia: which ®bers do we cut?

O. Korn, I. Braghetto, P. Burdiles, A. Csendes

Department of Surgery, Clinical Hospital University of Chile, Santiago, Chile

SUMMARY. Until now, it has not been quite clear which muscular ®bers are cut when a cardiomyotomy forachalasia is carried out. In the present report, in a human achalasic gastroesophageal specimen, the mucosa of thestenotic segment was stripped o�, allowing the ®bers of the inner muscular coat to be seen. In addition, threecardiomyotomies at di�erent sites were simulated. In achalasic specimens, the stenotic area is formed by thesemicircular (`clasp') and oblique (`sling') muscular ®bers. Di�erent myotomies section these two muscular bands indistinct proportions. The stenotic segment in achalasia coincides topographically with the anatomic loweresophageal sphincter area. The site of cardiomyotomy is not irrelevant because this sphincter is not an annularmuscle and the two muscular components of the sphincter can be sectioned in di�erent ways. This may be importantin post-operative results with regard to the relief of dysphagia and the appearance of gastroesophageal re¯ux.

INTRODUCTION

Achalasia is the best known primary motility disorderof the esophagus and has been extensively studiedfrom experimental, pathophysiologic and clinicalpoints of view.1,2 However, macroscopic anatomicstudies about this entity are scarce.3,4 On the otherhand, it is widely accepted and there is strongevidence that lower esophageal sphincter (LES)dysfunction is the principal cause of this disease,5

but this hypothesis is based on functional or indirectmethods and, until now, there has not been acorrelation shown between LES abnormality andmacroscopic ®ndings that has been accuratelyproved.

The aim of this report is to show for the ®rst timein the literature the muscular anatomy of the stenoticsegment from a human achalasic gastroesophagealspecimen and to discuss the implications of the®ndings for medical and surgical therapies.

CASE REPORT

The patient, a 58-year-old woman, was admitted toour department in October 1998. Her presentingsymptoms were dysphagia and pseudoregurgitation,

which had progressively worsened during the lastyear. The diagnosis of achalasia had been made 3years before after a radiological study of the esopha-gus, but the patient refused all further investigationsand any treatment at that time. After admission toour department, the endoscopy showed a dilated,atonic and tortuous esophageal body, a closed cardiathat failed to open with air insu¯ation but that waseasily passed through by endoscope. The bariumcontrast radiograph showed typical ®ndings: esopha-geal dilatation (sigmoid-shaped esophagus), a nar-rowing at the level of the gastroesophageal junctionand absent peristalsis (Fig. 1). The manometricstudies demonstrated absence of peristaltic contrac-tions in the body of the esophagus and failure ofcomplete relaxation of the LES in response toswallowing. The LES resting pressure was 35 mmHg.The serological test for Chagas was negative.

Because of the large esophageal dilatation in thispatient, a cardiomyotomy was considered to beinappropriate and she was submitted to transhiataltotal esophagectomy with videoscopic assistance anda gastric tube pull-up interposition.

The surgical piece comprised the whole esophagusand the proximal segment of the stomach. The freshspecimen was ®lled with water to show the stenoticsegment at the level of the gastroesophageal junction.The proximal and distal limits of the narrowing weremarked with silk stitches by the greater curvature.Afterwards, the specimen was opened longitudinallyby the greater curvature, ®xed on a tray to prevent

Address correspondence to: Owen Korn, Department of Surgery,Clinical Hospital University of Chile, Santos Dumont 999,Santiago, Chile. Fax: (+56) 2 777 5043.

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unfolding and immediately submerged in a 10%formalin solution.

In Fig. 2, the unopened specimen is shown,displaying the longitudinal muscular ®bers of theexternal coat and the dilated esophageal body prox-imal to the stenosis. The mucosa was stripped o� in ablock to expose the inner muscular coat. In themucosa block, it was possible to observe thesquamous±columnar junction (Z-line) approximatelyin the middle of the stenotic zone.

In the inner muscular coat of the stenotic segment,it was easy to recognize two di�erent muscle bundles:at the lesser curve, the short semicircular muscular®bers (`clasp') and at the greater curvature the shortand long oblique muscular ®bers (`sling') (Fig. 3), i.e.the lower esophageal sphincter, according to thedescription by Liebermann et al.6

Based on these ®ndings, we performed a schematicreconstruction of the muscular architecture of thestenotic segment and simulated in it three distinctsmyotomies, enabling which ®bers are sectioned witheach one to be seen (Fig. 4).

COMMENTS

This case represents the ®rst anatomic con®rmationthat the stenotic segment in achalasia coincides

topographically with the anatomic lower esophagealsphincter and at the same time can serve as newevidence that the LES is formed by two muscularunits: the `clasp' and oblique short and long ®bers(`sling'). This latter group has been known for longtime,7 but now they must be de®nitively recognized asone of the two components of the LES to avoid themistake of considering them as a narrow musclebundle in the distal limit of a `circular' sphincter8 oras the proximal part of the stomach.

Thus, if there is no annular muscle which encirclesthe gastroesophageal junction, it is hard to supportthe theory that pneumatic dilatation provokes thestretching or rupturing1 of a non-existent circularmuscle. Actually, there is more anatomical basis tosupport that the dilatation provokes the disruption ofthe connective unions6 between the clasp and theoblique ®bers, maintaining certain sphincteric indem-nity5 which could explain the lower incidence ofgastroesophageal re¯ux after the procedure and thegreater tendency to recurrence of dysphagia, whichdemands new dilatations.

On the other hand, the surgical procedure cutsdrastically and irreversibly the muscular ®bers of the

Fig. 1ÐBarium contrast radiograph showing the large esophagealdilatation (sigmoid-shaped esophagus) and the narrowing at thelevel of the gastroesophageal junction.

Fig. 2ÐUnopened gastroesophageal specimen (after ®xation)showing longitudinal muscular ®bers of the esophagus externalcoat and the dilated esophageal body proximal to the stenoticsegment, marked by silk stitches.

Cardiomyotomy in achalasia 105

sphincter.9 Once again, if the LES was an elastic ring,the result would be the same wherever it was cutbecause the sphincteric action would be lost. How-ever, as this particular sphincter is formed by twomuscular units with a peculiar arrangement, the sameresult is not obtained if the cut to section thegastroesophageal junction is made closer to the lessercurve or to the greater curve or in the middle of it.Until now, we did not know whether both muscularbands had the same importance in the sphinctericcompetence, although there was some evidence thatshowed that the oblique ®bers have a greater tensionin response to cholinergic stimulation than the clasp®bers.10

Unfortunately, the surgeon does not have anyopportunity to see the ®bers before sectioning them.Nevertheless, the recommendations from someauthors11,12 regarding the myotomy not extendingmore than a few millimeters from the gastroesopha-geal junction is absolutely reasonable because in thisway the oblique ®bers of the sphincter are preserved.

Thus, the surgical dilemma in achalasia is di�cultto resolve as it is necessary to destroy the sphincter inorder to relieve the dysphagia, but the naturalconsequence is gastroesophageal re¯ux. Therefore,we probably need to destroy the sphincter but not toa great extent; however, for this, we need to knowhow this particular sphincter works13 and for themoment the ®rst step is to understand its anatomy.14

Fig. 3ÐSpecimen opened by the greater curve with the mucosal coat removed. The inner muscular coat is exposed. The narrowed segment isshaped by two di�erent muscle bundles: at the lesser curve, the short semicircular muscular ®bers (`clasp') and at the greater curvature theshort and long oblique muscular ®bers (`sling').

Fig. 4ÐSchematic drawing showing three di�erent myotomies andthe muscular ®bers which are sectioned with each one. (A) Closerto the lesser curve: only `clasp' ®bers are sectioned; (B) on themiddle of the gastroesophageal junction: both muscular bundlesare damaged; (C) closer to greater curve: only `oblique' ®bers aredamaged.

106 Diseases of the Esophagus

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