Adult Chest Surgery

Chapter 26. Esophagocardiomyotomy for Achalasia (Heller) 

 

In 1914, Ernest Heller first described the double-cardiomyotomy technique, one anterior and one posterior along the gastroesophageal junction (GEJ), for the surgical treatment of achalasia.1 This operation was modified subsequently such that only an anterior myotomy is currently performed. This operation has yielded excellent results, with 90–95% of patients receiving durable relief of dysphagia.2–6 At the University of Washington, we converted from a thoracoscopic approach to a laparoscopic Heller myotomy in 1994. Along with several major centers, we now consider laparoscopic esophageal myotomy to be an excellent first-choice therapy because of the low morbidity of minimally invasive techniques and the high levels of success after myotomy.3,6–8 Moreover, surgery provides the most dependable long-term relief of dysphagia, permitting accurate division of the muscle fibers of the lower esophageal sphincter (LES) rather than blind disruption, as with dilation.2

NATURAL HISTORY

Achalasia is an esophageal motility disorder characterized by aperistalsis of the esophageal body combined with lack of LES relaxation. The most common primary esophageal motility disorder, achalasia, is still relatively uncommon, with a reported incidence of 0.5–1 per 100,000 people in North America. First described as cardiospasm over 300 years ago, the name achalasia was coined by Lendrum in 1937, literally meaning "failure to relax."9,10

The disease manifests with progressive dysphagia, first to solids and then to liquids, in individuals between the ages of 20 and 50 years (but often both earlier and later in life). No gender predilection exists. Ineffective relaxation of the LES and loss of esophageal peristalsis lead to impaired emptying and gradual esophageal dilatation, resulting in severe dysphagia. Patients also may complain of regurgitation (commonly of undigested food), cough, aspiration, wheezing, and choking, often made worse by assuming the supine position for sleep, when esophageal contents flow back into the airway. Stress or cold liquids may exacerbate symptoms. Chest pain is reported commonly, although it is of unclear etiology because most patients have no peristalsis. Distention and uncoordinated peristalsis are often postulated as a cause. A subset of patients has simultaneous contractions of normal or near-normal amplitude on manometry, a variation often called vigorous achalasia. These simultaneous contractions are postulated as one cause of chest pain, similar to other hypercontractile esophageal motility disorders. Overdistention of the esophagus may also contribute to pain. Heartburn may occur but is usually the result of fermentation of unevacuated food in the esophagus and not gastroesophageal reflux.6 Delay in treatment, however, is usually a result of misdiagnosis, where achalasia is mistaken for gastroesophageal reflux disease (GERD). Recurrent aspiration pneumonia is another presenting symptom of achalasia that can sidetrack clinicians and requires exclusion of airway lesions or malignancy.

Mild weight loss is a late manifestation of the disease. Rapid or significant drop in weight of more than 10 lb (4 kg) should alert clinicians to the possibility of an esophageal malignancy that has caused obstruction. This entity is often referred to as pseudoachalasia. If any diagnostic doubt exists, CT should be considered. Alternatively, if available, esophagogastroscopy combined with endoscopic ultrasound is a highly specific and sensitive method of confirming or excluding tumors and can be used to simultaneously biopsy suspicious masses or lymph nodes. Advanced age and short duration of symptoms with rapid onset are additional clinical features that should alert practitioners to investigate malignancy.

Patients often report gulping large amounts of liquids to relieve a relatively obstructed esophagus or to avoid chest pain and regurgitation. Patients may use various maneuvers to attempt to clear the esophagus, including standing after swallowing, walking around during meals, raising hands over head, and extending or flexing the neck. For some, flushing the esophagus with carbonated beverages also works when water fails.

PREOPERATIVE ASSESSMENT

Manometry

The standard of achalasia diagnosis is esophageal manometry. Classically described findings are aperistalsis of the mid- and lower esophageal body and incomplete relaxation of the LES (Figs. 26-1 and 26-2). The body of the esophagus typically demonstrates nonpropagated or undulating isobaric simultaneous waves owing to the transmission of pharyngeal and upper esophageal contractions down the fluid-filled esophagus. Vigorous achalasia has simultaneous normal or high-amplitude waves without normal progression. Although the LES usually fails to relax completely, occasionally we see patients with all other characteristics of achalasia and a relaxing LES. Such disorders are likely variants of achalasia, but aperistalsis is necessary to make the diagnosis.

Figure 26-1.

 

Manometry tracing showing aperistalsis of the esophageal body (white arrow) and incomplete LES relaxation (red arrow). Top four impedance tracings showing no drop in impedance and lack of bolus transit (black arrow).

 

Figure 26-2.

 

Normal esophageal manometry with progression of peristaltic wave and LES relaxation. Top four tracings show normal progressive drop in impedance followed by recovery after bolus transit.

Upper Gastrointestinal Series

Findings on upper gastrointestinal studies usually include esophageal dilatation and tapering of the GEJ (Fig. 26-3). As the esophagus dilates, it may become sigmoid-shaped. An air-fluid level in the esophagus is seen commonly, arising from slow clearance of the contrast material bolus. Particulate food matter may be seen in the contrast material, even though patients fast for several hours before study. Irregularity, nodularity, or a hint of mass lesions requires esophagogastroscopy and endoscopic ultrasound for confirmation. CT scan is also recommended.

Figure 26-3.

 

Upper gastrointestinal esophagram showing a dilated esophagus and incomplete relaxation of the LES, allowing minimal fluid passage.

Esophagogastroscopy

Endoscopic findings include normal mucosa, usually without stigmata of reflux or esophagitis. Patients with long-standing achalasia may have thicker, abnormal mucosa. Retained food or fluid is often found. Passage of the endoscope through the LES has been described as a "pop" or "sudden release." The esophagogastroscopy is often completely normal but is required to rule out pseudoachalasia.11

SURGICAL ENDOSCOPIC TREATMENTS

Before laparoscopic techniques were developed, and despite the superior long-term results from surgical myotomy via a left thoracic approach, many patients were treated, at least initially, with less invasive therapies such as dilation. In fact, the concept of dilating the LES to provide relief for patients with achalasia is centuries old. Today, endoscopic techniques such as pneumatic dilation and endoscopic administration of botulinum toxin are used commonly as first-line treatments before surgery.

ENDOSCOPIC DILATION

Only with the advent of pneumatic balloons did dilation of the LES become a relatively effective and predictable treatment of achalasia. In fact, today, pneumatic balloon dilation is the most common first-line treatment for achalasia. After screening endoscopy to rule out peptic stricture, Schatzki ring, malignancy, or other obstructive source, balloon dilation can be performed. The fasting patient is sedated and placed in the left lateral position with monitoring of vital signs and oxygenation. A guidewire is positioned in the stomach, and a balloon, such as the Microvasive Rigiflex® Balloon Dilator (Microvasive Inc., Watertown, MA), is passed over the guidewire. Accurate balloon placement at the GEJ is confirmed with a pediatric endoscope. Under fluoroscopy, the balloon is distended 10 psi for 60 seconds. A range of sizes is available (3.0, 3.5, and 4.0 cm). A water-soluble contrast agent swallow is followed by barium 4 hours after the procedure to exclude perforation.

Results

Pneumatic dilation has been shown to reduce LES pressure by 39–68%. Initial relief with modern balloons varies greatly, with some studies showing 75–95% symptom relief, usually after two to three dilations. Most long-term studies demonstrate persistent relief of dysphagia in 60–65% of patients. Recently, however, reports with follow-up approaching 15 years show 5-year remission rates closer to 40% with single dilation and 10-year success rates of only 36%. Predictors of success include age over 40 years and postdilation LES pressure of less than 10 mm Hg. Younger patients and those with high LES pressures are less likely to respond to dilation and therefore should be considered for surgical therapy early.

Complications

Rates of esophageal perforation with pneumatic dilation range from 2% to 6.4% in most large studies, and the risk increases progressively with larger balloons. Depending on the characteristics of the perforation, emergent surgery may be required, whereas some patients can be managed with fasting, antibiotics, and hospital admission. Reports of perforation with even the smallest balloons exist. Increased risk has been reported in patients with smaller-diameter esophagi (3 cm), large sigmoid-shaped esophagi, or a history of previous dilations. Submucosal hematoma may occur occasionally and can cause delayed fibrotic strictures. Some surgeons report that dilation may make subsequent esophageal myotomy more difficult as a result of fibrosis of muscle and loss of the mucosal/muscle planes, although this is not universally observed or accepted.

Cost-Effectiveness

When comparing single treatments, dilation is reportedly more cost-effective than surgery ($3245 versus $10,800 in 1998). However, in light of the 5- to 10-year remission rate of only 40% with surgery, the costs of dilation greatly increase per patient-year, rendering surgery a comparatively more attractive and potentially cost-effective therapy.

ENDOSCOPIC BOTULINUM TOXIN

Endoscopic injection of botulinum toxin (Botox) into the LES gained rapid popularity in the mid-1990s. Initial reports showed excellent immediate symptom relief and sustained effects for several months. Enthusiasm for this therapy was greatly tempered, however, by long-term failure in most patients.

Most patients receive initial relief for 1–6 months, although success rates at 1 year range from 13% to 65%. The majority of patients require repeated injections within the year to sustain relief. Randomized controlled trials comparing botulinum toxin injection with surgical myotomy have shown greater long-term symptom resolution with surgery (90% versus 34%). Pneumatic dilation also has been demonstrated to be superior to botulinum toxin injection, with 70% versus 32% of patients symptom-free at 1 year. Esophageal motility and barium studies fail to show any measurable change in LES relaxation or esophageal dilatation after botulinum toxin injections. Furthermore, several studies have shown an increase in the difficulty of performing surgery after botulinum injection. Fibrosis between the submucosa and circular muscle layer of the esophagus results in a higher likelihood of mucosal perforation, further underscoring some of the potential downsides to this treatment.

Complications

Esophageal wall hematoma has been reported and can cause fibrotic rings that exacerbate dysphagia and potentially complicate further management. Antibodies to botulinum toxin, which many people form, have been associated with diminished response.

Cost-Effectiveness

With the high relapse of symptoms and repeated injections required to achieve symptom relief, botulinum injection is not cost-effective, especially in young patients. Most clinicians currently reserve botulinum toxin for poor surgical candidates, those unable to undergo pneumatic dilation or surgery, and those who prefer such treatment despite the evidence.

SURGICAL TREATMENT WITH LAPAROSCOPIC (HELLER) MYOTOMY

Traditionally, surgical myotomy was accomplished via open transthoracic or transabdominal approach, both of which are associated with the morbidity of a major open procedure and hospital stays of 7–10 days. The application of minimally invasive laparoscopic technique has expanded the use of the Heller myotomy and improved the overall risk-benefit ratio.

The laparoscopic approach has been demonstrated to be superior to both open and thoracoscopic procedures with respect to complications, morbidity, mortality, relief of dysphagia, prevention of postoperative reflux, and operative times.12,13 Additional advantages of the laparoscopic approach include improved visualization of the esophageal muscle layers, better access to perform a longer myotomy owing to improved esophageal and gastric access, and substantial reduction in postoperative pain.

Our preference for the laparoscopic approach to Heller myotomy grew from experience and is based on two distinct reasons. First, we recognized that the limited gastric myotomy (0.5–1.0 cm) afforded by the thoracoscopic approach did not protect the patient from gastroesophageal reflux. In fact, when pH monitoring was performed, 80% of patients had pathologic reflux.14 Second, many patients (17% in our experience) returned with recurrent dysphagia, half of them requiring an extension of the myotomy (on the gastric side) by laparoscopy. The laparoscopic approach permitted a long esophageal myotomy that could be extended onto the stomach (1.5–2.0 cm).

Between 1994 and 1998, 52 patients were operated on using this approach, with the majority having excellent improvement in their dysphagia (over 90%). Still occasional patients had inadequate relief or recurrence of dysphagia, and some of them saw improvement when the myotomy was extended still further on the stomach. Therefore, in 1998, we began extending the myotomy a full 3 cm on the gastric side. We also began performing a Toupet rather than a Dor fundoplication. We reasoned that an anterior fundoplication would be more difficult with a 3-cm cardiomyotomy and suspected that the posterior Toupet would provide better control of reflux.

A comparison of the two approaches confirmed our suspicions. The extended myotomy with Toupet fundoplication more effectively obliterated the LES than the shorter myotomy with Dor fundoplication, as evidenced by the residual LES pressure (9.5 versus 15.8 mm Hg, respectively). Dysphagia was both less frequent (once a month versus once a week on average) and less severe (3.2 versus 5.3 on a 10-point visual analog scale) in the extended myotomy with Toupet fundoplication group. Most important, to date, no patient has required surgical intervention for recurrent dysphagia, and endoscopic treatment is rare (only 2 in more than 100). Moreover, completely obliterating the LES did not result in more reflux because the mean distal esophageal acid exposure was equivalent between the two groups (extended myotomy with Toupet fundoplication 6.0% versus shorter myotomy with Dor fundoplication 5.9%).7

The other major controversy concerns which antireflux fundoplication should be performed. Relief of dysphagia is the ultimate goal of treatment, and no technique exists that always relieves dysphagia without some resulting reflux. Recurrent dysphagia seen in up to 14% of patients is avoided and increased reflux is minimized when a 3-cm cardiomyotomy and partial fundoplication are performed.

OPERATIVE TECHNIQUE

The patient is placed in a modified lithotomy position with a beanbag allowing steep reverse Trendelenburg position. Five standard ports are placed (Fig. 26-4). We position the camera port 10–12 cm medial and caudal to the left upper quadrant port, usually 3 cm left and 3 cm rostral to the umbilicus. Sequentially, the surgeon places his or her left hand in the right upper quadrant near the costal margin, the assistant's right hand is in the left lateral lower quadrant, and a fan liver retractor is located in the right lateral quadrant.

Figure 26-4.

 
 

Positioning and port placement allow access to the hiatus, with care to avoid pressure points and to maintain joint neutrality.

 

Starting at the left anterior diaphragm near the esophageal hiatus, we divide the left phrenogastric ligament, thereby exposing the posterior left crus. This facilitates division of the superior-most short gastric vessels and releases the spleen. We mobilize the gastric fundus, dividing the proximal short gastric vessels and posterior attachments of the proximal stomach to minimize tension on the subsequent fundoplication. We approach the gastrohepatic ligament and anterior phrenoesophageal ligament, advancing over the esophagus. Here it is important to avoid deep dissection and the vagus nerve. We then complete the posterior esophageal window by dissecting the base of the right crus and proceed under the esophagus to the previously exposed left crus (Fig. 26-5).

Figure 26-5.

 

Dissection and mobilization of the esophagus.

 

A Penrose drain may be placed behind the esophagus and used to provide caudal and lateral retraction during the mediastinal dissection, but this is usually not necessary. An extensive hiatal and mediastinal esophageal dissection is performed anteriorly to maximize the length of the myotomy and provide a proper tension-free Toupet fundoplication. The left (anterior) vagus is identified, protected, and separated from the esophagus to clear a path for the myotomy from the stomach to the esophagus. This is facilitated by dissecting the GEJ fat pad off the stomach from an inferior to superior approach, essentially lifting the vagus nerve.

A lighted 50F bougie is passed into the body of the stomach, serving both to illuminate the esophagus and the muscle layers and to provide a stable platform on which to perform the myotomy. After the fat pad overlying the cardioesophageal junction is excised, a Babcock clamp is placed open over the bougie, just distal to the GEJ, providing exposure to the myotomy site and gently stretching the muscle fibers to aid in identification and division. The myotomy is performed with an L-shaped hook electrocautery device (Fig. 26-6). Very little cautery is actually required because the individual muscle fibers divide easily under gentle traction. Limiting the exposure to electrocautery also prevents delayed perforations from unrecognized thermal mucosal injury. The longitudinal muscle fibers are divided first, exposing the inner circular muscle, which is divided next, leaving the submucosa intact (Fig. 26-7). Controlling submucosal or muscle bleeding with gentle pressure and time prevents mucosal injury, and further intervention is rarely required. The distal dissection is most difficult owing to poor differentiation of the muscular layers and a thinner mucosa, especially at the GEJ. Care should be taken to extend the myotomy sufficiently onto the gastric cardia and divide all tangential sling fibers to avoid recurrent dysphagia. Mucosal perforations should be repaired with fine (4–0 or 5–0) absorbable suture and rarely require other intervention.

Figure 26-6.

 

The myotomy is carried as far proximally as possible (usually 6–8 cm) and at least 3 cm onto the stomach.

 

Figure 26-7.

 

The muscle fibers are divided to the plane between the circular muscularis and the submucosa.

 

After the myotomy is complete, we perform a standard Toupet fundoplication, securing both edges of the fundus to each side of the myotomy and to the diaphragm (Fig. 26-8). The hiatus is not closed except in the rare case of encountering a very large hiatal hernia. Should mucosal lacerations occur, a prudent choice is to perform a Dor anterior fundoplication to buttress the repaired mucosa to avoid esophageal leak or fistula.

Figure 26-8.

 

A standard Toupet fundoplication is performed after the myotomy, by securing both edges of the fundus to each side of the myotomy and to the diaphragm.

POSTOPERATIVE MANAGEMENT

Patients generally start liquids the night of their procedure, and nausea is treated aggressively with antiemetics. Average hospital stay is 1–2 days, and resumption of normal diet and activities occurs within 2–3 weeks. A trained nutritionist evaluates each patient postoperatively and provides dietary guidance. The patient is followed up at 1–3 weeks, and thereafter, follow-up is tailored to patient needs, including continued nutritionist input. We perform manometry and 24-hour pH studies on our patients 6 months after surgery to evaluate acid exposure, correlate symptoms with pH results, and assess outcomes.

CONTRAINDICATIONS

The inability to undergo surgery or general endotracheal anesthesia is an absolute contraindication. Previous hiatal or esophageal surgery may be a relative barrier to laparoscopic or open surgery. Prior esophageal perforations or thoracic operations may make mediastinal dissection and myotomy technically difficult. Knowledge of laparoscopic and open abdominal and thoracic approaches provides alternatives for those with prior operations or perforation.

Some believe that megaesophagus or grade IV dilatation (>8 cm) is a contraindication to a myotomy because of poor dysphagia relief and technical difficulty. By using minimally invasive techniques, however, little is lost or risked in attempting a myotomy while reserving esophagectomy for failures. Most patients with severe or even sigmoid-shaped esophagi are relieved of dysphagia and subsequently avoid esophagectomy and its higher associated morbidity and mortality (2–8%).4

COMPLICATIONS

Early Complications

Perforations occur in 1–5% of patients in most series, and most are recognized and repaired, adding little morbidity to or deleterious effect on successful relief of dysphagia. Pneumothorax, bleeding, intraabdominal abscess, and wound infection occur in approximately 3% of patients.15 Pneumothorax rarely requires treatment because the carbon dioxide used for insufflation is readily absorbed. Other complications, such as vagal injuries, unrecognized mucosal perforations, or splenic injuries, are reported but rare.

Bloating and the inability to belch occasionally bother patients after Nissen fundoplication. Patients rarely complain of similar symptoms after esophagomyotomy and fundoplication. Residual dysphagia usually disappears by 4–6 weeks. In most patients, bloating and abdominal discomfort resolve in this time period as well. If symptoms remain after 3 months, investigation with an upper gastrointestinal study and esophagogastroscopy should be performed to assess fundoplication orientation, position, and potential scarring of the myotomy.

Late Complications

Postoperative complications related to recurrent dysphagia and reflux account for most clinically relevant problems with esophagomyotomy and fundoplication. Occasionally, diarrhea occurs, possibly owing to increased bowel osmotic load or changes in gastric emptying. In many patients, recurrent dysphagia is caused by insufficient myotomy length. Lengthening the myotomy can be approached laparoscopically and usually alleviates the dysphagia in these patients.

CONTROVERSIES

Whether to perform an antireflux procedure is no longer controversial. It is uniformly accepted as good practice. The last large American surgical group that advocated against performing fundoplication recently published a randomized study and concluded that a partial fundoplication provided better control of reflux without adversely affecting the relief of dysphagia.16

Dor or Toupet Fundoplication

Which antireflux procedure to perform, however, does remain a matter of debate. Reported results of postoperative reflux after lower esophageal myotomy with Dor fundoplication range from 4% to 25%, with larger studies ranging between 5% and 18%.16,17 Several studies support use of the Toupet fundoplication, reporting similarly successful results.18,19 We find that the Toupet fundoplication provides an effective barrier to reflux while avoiding recurrent dysphagia.

Most surgeons find that performing an antireflux procedure in conjunction with laparoscopic myotomy does not add significant time or morbidity to the operation and is not associated with increased postoperative dysphagia. Certainly, a partial fundoplication (e.g., Dor or Toupet) is the best option. A total fundoplication (e.g., Nissen) may cause a functional obstruction for a nonpropulsive esophagus, resulting in a high incidence of dysphagia.

Both anterior and posterior fundoplications have their merits, and at this point the choice should be at the discretion of the surgeon.

SUMMARY

In this modern era of minimally invasive surgery, for most patients, the initial and only treatment of achalasia should be a laparoscopic Heller myotomy with partial fundoplication. When the LES is completely obliterated by extending the myotomy at least 3 cm below the GEJ, excellent long-term success can be achieved in most patients.

EDITOR'S COMMENT

While I agree that a 3-cm myotomy into the gastric area is important, my preference is to use the Dor fundoplication for two reasons. First, it provides a solution for potential microperforation that may occur during the dissection. Second, it obviates the necessity of dissecting the posterior window, thereby providing additional protection to the vagus nerve.

Another rather common presentation is the patient with dysphagia and achalasia after myotomy (open or minimally invasive). This disorder often is caused by incomplete myotomy of the stomach portion and can be dealt with laparoscopically, regardless of the previous approach. I generally try to create the new myotomy along the greater curve of the stomach and the left lateral wall of the esophagus, which are generally virgin territories.

An important technical pearl concerns the best way to manage bleeding from the esophageal muscle. Here, compression and patience are key, as too much cautery is likely to result in mucosal injury. Finally, I recently discovered that the myotomy can be rapidly and efficiently accomplished by using the LigaSure device (ValleyLab, Boulder, CO).

–RB

REFERENCES

1. Heller E: Extramukose kardioplastik beim chronischen kardiospasmus it dilatation des oesophagus. Mitt Grenzgeb Med Chir 27:141–9, 1914. 

2. Pellegrini CA: Impact and evolution of minimally invasive techniques in the treatment of achalasia. Surg Endosc 11:1–2, 1997.[PubMed: 8994977]

3. Oelschlager B, Pellegrini CA: Surgical management of achalasia. Med Gen Med 5:31, 2003.[PubMed: 14745378]

4. Patti MG, Fisichella PM, Perretta S, et al: Impact of minimally invasive surgery on the treatment of esophageal achalasia: A decade of change. J Am Coll Surg 196:698–703; discussion 703–5, 2003. 

5. Chapman JR, Joehl RJ, Murayama KM, et al: Achalasia treatment: Improved outcome of laparoscopic myotomy with operative manometry. Arch Surg 139:508–13; discussion 513, 2004. 

6. Woltman TA, Oelschlager BK, Pellegrini CA: Surgical management of esophageal motility disorders. J Surg Res 117:34–43, 2004.[PubMed: 15013712]

7. Oelschlager B, Chang L, Pellegrini C: Improved outcome after extended gastric myotomy for achalasia. Arch Surg 138:490–5; discussion 495–7, 2003. 

8. Zaninotto G, Annese V, Costantini M, et al: Randomized, controlled trial of botulinum toxin versus laparoscopic Heller myotomy for esophageal achalasia. Ann Surg 239:364–70, 2004.[PubMed: 15075653]

9. Lendrum F: Anatomic features of the cardiac orifice of the stomach with special reference to cardiospasm. Arch Intern Med 59:474–511, 1937. 

10. Spiess AE, Kahrilas PJ: Treating achalasia: From whalebone to laparoscope. JAMA 280:638–42, 1998.[PubMed: 9718057]

11. Moonka R, Patti MG, Feo CV, et al: Clinical presentation and evaluation of malignant pseudoachalasia. J Gastrointest Surg 3:456–61, 1999.[PubMed: 10482700]

12. Ramacciato G, Mercantini P, Amodio PM, et al: The laparoscopic approach with antireflux surgery is superior to the thoracoscopic approach for the treatment of esophageal achalasia: Experience of a single surgical unit. Surg Endosc 16:1431–7, 2002.[PubMed: 12072992]

13. Luketich JD, Fernando HC, Christie NA, et al: Outcomes after minimally invasive esophagomyotomy. Ann Thorac Surg 72:1909–12; discussion 1912–3, 2001. 

14. Patti MG, Pellegrini CA, Horgan S, et al: Minimally invasive surgery for achalasia: An 8-year experience with 168 patients. Ann Surg 230:587–93; discussion 593–4, 1999. 

15. Martins P, Morais BB, Cunha-Melo JR: Postoperative complications in the treatment of chagasic megaesophagus. Int Surg 78:99–102, 1993.[PubMed: 8354622]

16. Richards WO, Torquati A, Holzman MD, et al: Heller myotomy versus Heller myotomy with Dor fundoplication for achalasia: A prospective, randomized, double-blind clinical trial. Ann Surg 240:405-12; discussion 412–5, 2004. 

17. Donahue PE, Horgan S, Liu KJ, Madura JA: Floppy Dor fundoplication after esophagocardiomyotomy for achalasia. Surgery 132:716–22; discussion 722–3, 2002. 

18. Hunter JG, Trus TL, Branum GD, Waring JP: Laparoscopic Heller myotomy and fundoplication for achalasia. Ann Surg 225:655–64; discussion 664–5, 1997. 

19. Parrilla Paricio P, Martinez de Haro L, Ortiz A, Aguayo J: Achalasia of the cardia: Long-term results of oesophagomyotomy and posterior partial fundoplication. Br J Surg 77:1371–4, 1990. 



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