Thoracoscopic and Laparoscopic Myotomy

Achalasia is an uncommon disorder of the esophagus. The disorder is characterized by inadequate relaxation of the lower esophageal sphincter (LES) and concomitant loss of peristalsis in the body of the esophagus. (See the images below.) Patients are usually young and often present with dysphagia to both solids and liquids at the same time. Other symptoms may include regurgitation, chest pain, aspiration, and weight loss. The disorder is often mistaken for gastroesophageal reflux (GER) disease (GERD), and this mistake is a common reason for a delay in diagnosis of achalasia.

Achalasia is most common between the second and fifth decades of life but has been reported in people of all ages.[1] In the United States, the incidence is about 1 per 200,000 population.

With achalasia, the essential problem involves lack of normal esophageal motility and a hypertonic LES that fails to relax. The aim of surgery is to disrupt the muscle fibers of the LES to relax the esophagus and allow for passage of food.

Today, many surgeons offer a laparoscopic procedure for the treatment of achalasia. Studies have shown that this surgery offers durable results with good short-term benefits. More than 90% of patients have relief of their symptoms immediately after surgery. In addition, the use of minimally invasive surgery has reduced the morbidity associated with open esophageal surgery. A thoracoscopic procedure has also been performed. (See Technique.)

There are many treatments for achalasia. Over the years, the role of surgery has become better defined. For mild cases of achalasia, medical therapies still play a role. Even though several medical therapies are available, the response is variable among patients, and the benefits are not sustained for longer than a few months, at best. Botulinum toxin and pneumatic dilatation may be good choices in patients who want to wait or would like a nonsurgical alternative. However, repeated balloon dilatation is associated with a risk of esophageal perforation, which appears to occur in 1-3% of cases.

Minimally invasive surgery has now supplanted most medical therapies for achalasia.[2, 3, 4, 5, 6, 7] The minimally invasive approaches have a far lower morbidity and mortality than the open technique does. More than 90% of patients find effective relief from dysphagia. For those who have associated GERD, an antireflux procedure can be combined without any added morbidity.

Etiology of achalasia

Achalasia has been known to occur for more than 200 years, but its cause still remains unknown. Biopsy of the mucosa in the affected part of the esophagus often reveals loss of ganglion cells and fibrosis of myenteric plexus.

This process is likely autoimmune-regulated, given that T cells predominate in the inflammatory infiltrate.[8] Additional research has shown that achalasia patients have decreased nitric oxide synthase in the myenteric plexus, resulting in reduced nitric oxide production.[9] Because nitric oxide is a key factor in gastrointestinal (GI) smooth-muscle relaxation, its decreased presence at least partly explains the dysfunction of the LES.

Symptoms of achalasia

The hallmark symptom of achalasia is progressive dysphagia, often first to solids and then to liquids. Because the dysphagia usually worsens very gradually, it is often quite severe upon presentation. Most patients adapt their eating behavior long before the diagnosis is made. Because stress and cold liquids may exacerbate the dysphagia, both liquids and solids may be poorly tolerated simultaneously at presentation.

Chest pain is also a common symptom, and patients often undergo extensive cardiac evaluation prior to diagnosis. Previously, 10-39% of patients suffered bronchopulmonary complications from repeated regurgitation and aspiration.[10] Many of these complications can now be avoided through earlier diagnosis and treatment. Dyspepsia occurs in about one fourth of cases, though it is usually caused by fermentation of unevacuated food in the esophagus rather than GER.[11]  

Also common, though often not mentioned, are the symptoms caused by fungal infection. The residual food in the esophagus makes this structure a prime target for Candida, and the resulting infection can be quite severe. Medical treatment is required to manage the candidal infection, but recurrence is common as long as achalasia persists.[12]

Patients often have a long history of symptoms—in some cases, longer than 30 years. Weight loss is common, though patients usually alter their diets enough to maintain body mass until the disease becomes intolerable and they seek therapy. Acute onset of symptoms or rapid weight loss should be a red flag for clinicians to rule out malignancy. Ruling out pseudoachalasia (presence of a distal esophageal tumor causing dysphagia) in older patients (>55 y) is crucial,[13]  as is ruling it out in those with a shorter duration of symptoms (< 6 mo), or more profound, rapid weight loss (>15 lb [~7 kg]).

Any patient with a questionable diagnosis should undergo a careful evaluation, to include the use of endoscopic ultrasonography (US) and computed tomography (CT) to rule out pseudoachalasia.[11]

Sigmoid-shaped esophagus or megaesophagus

Some patients with achalasia develop a megaesophagus, which is usually the end stage of achalasia. This disorder is characterized by an aperistaltic esophagus and failure of the LES to relax. Over time, progressive dilatation and lengthening of the esophagus occurs. In the past, the only surgical option these patients had was total esophagectomy because no matter what type of surgery was performed, the dilated and tortuous esophagus had no motility and dysphagia persisted.

In the past decade, some surgeons have been offering laparoscopic myotomy to these patients. The myotomy significantly lowers the morbidity and mortality that is associated with a total esophagectomy. Initial studies indicated that laparoscopic myotomy was beneficial in these patients and provided moderate-to-excellent relief of symptoms. Short-term evaluation of these patients revealed no reflux and improvement of dysphagia. Unfortunately, the majority of these reports are anecdotal case reports. There remains a need for long-term data. 

To be able to undergo a laparoscopic myotomy under general anesthesia, the patient must be surgically fit. A relative contraindication may be prior esophageal or hiatal hernia surgery. Some surgeons feel that a megaesophagus or grade 1V dilatation (>8 cm) is a contraindication for myotomy because poor relief from dysphagia occurs. Instead, these patients may be better served with an esophagectomy.

Another group of patients who may not be served well with surgery are the elderly. These patients may best be managed with medical therapies (eg, botulinum toxin or dilatation). 

In any case, other surgeons feel that a minimally invasive procedure may be attempted, and an esophagectomy can then be performed if the minimally invasive procedure fails.

Best practices

No absolute rule exists regarding the extent of the myotomy. In the past, most surgeons have elected to perform a myotomy of 3-5 cm. (See the image below.) However, numerous studies have shown a direct correlation between length of myotomy and relief from dysphagia. Ample evidence shows that a myotomy shorter than 1 cm on the gastric wall is associated with persistent dysphagia. Most experts recommend making a myotomy of about 1.5 cm over the gastric wall to ensure that no residual dysphagia exists. Some surgeons also recommend that extending the myotomy to about 3 cm has better outcomes, but long-term results with this approach are unavailable.

A controversial aspect of laparoscopic myotomy is whether to perform an antireflux procedure at the same time. Some surgeons recommend performing a simultaneous antireflux procedure each and every time, but others maintain that the addition of the procedure should depend on the patient and the status of the esophagus.[14]

Long-term outcome data from the open surgical era have suggested successful relief of dysphagia in 65-70% of patients. However, most of these patients underwent open thoracotomy with minimal extension of the myotomy onto the stomach. This lack of sufficient myotomy onto the cardia has been proved to be the cause of most recurrent dysphagia after thoracoscopic or open myotomy via the chest. Additionally, many of these late failures were the result of severe, intractable reflux affecting quality of life and necessitating surgical intervention.[15]

Since the advent of the abdominal approach, and because laparoscopic techniques greatly improve visualization and allow longer transabdominal myotomies, success rates have improved dramatically. Several authors have now supported performing the myotomy with intraoperative endoscopic or manometric guidance to ensure complete obliteration of the LES. Specifically, the sling fibers of Willis (the oblique component of the LES) must be surgically divided to provide adequate passage of food.

Transthoracic approaches also make performing an antireflux procedure more difficult. These problems have been substantially corrected with laparoscopic techniques. Long-term outcomes for dysphagia in patients undergoing a laparoscopic Heller myotomy and antireflux procedure have ranged from 80% to 95% in large studies. Results for control of reflux may be inferior to results for dysphagia.

Before surgery for achalasia is undertaken, the patient's fitness for the procedure must be determined. A significant number of patients with chronic achalasia have weight loss in excess of 20 lb and may not be in ideal physical shape for surgery. In addition, loss of muscle mass in the upper chest may also limit the patient's ability to cough and to be weaned off the ventilator. A thorough evaluation of the patient by an internist may be necessary. In cases of severe weight loss, balloon dilatation may be used first to enable the patient to gain weight. In addition, any candidal infection must be treated before the surgical procedure.

Contrast esophagography

The preferred initial diagnostic test for most patients who present with progressive dysphagia is contrast esophagography. This inexpensive and readily available study often reveals the classic findings of a dilated esophagus, impaired peristalsis, and the pathognomonic smooth tapering at the esophagogastric junction (EGJ) commonly termed "bird's beak" esophagus.

If diagnosed early, the esophagus may be of normal caliber, though most patients present with some element of dilatation. Commonly, an air-fluid level forms as esophageal emptying is delayed, or the barium tablet or marshmallow "hangs up" just above the EGJ and may require several minutes to pass. Food particles are often seen despite patients' fasting for several hours prior to the study, indicating a significant delay in esophageal emptying. In long-standing achalasia, the esophagus can become dilated and tortuous and has been termed sigmoid-shaped or megaesophagus.

Manometry

Manometry is essential in making the diagnosis, with the vast majority of patients exhibiting the classic findings of incomplete lower esophageal sphincter (LES) relaxation and aperistalsis of the esophageal body.[16]  In a minority of patients, manometry tracings show simultaneous contractions, often of normal amplitude, which some have referred to as "vigorous achalasia."

A common misconception is that the LES must also be hypertensive. Although the LES pressure can occasionally be elevated, most patients have normal LES pressures (< 45 mm Hg) with incomplete LES relaxation with deglutition. Unfortunately, manometry is not available in all centers, and many surgeons proceed to surgery without manometric findings. There are data to support the view that manometry is not needed in all cases of achalasia.[17]

Endoscopy

Endoscopy is necessary to exclude pseudoachalasia and to evaluate for atypical anatomy (eg, epiphrenic or traction diverticula). Characteristic endoscopic findings include a dilated esophagus with failure of the LES to open with insufflation and some mild resistance to passage of the scope through the EGJ, commonly described as a "pop." Retained food and debris in the esophagus are common. If suspicion of pseudoachalasia persists, endoscopic ultrasonography (US) with biopsy and computed tomography (CT) should be included in the evaluation. Endoscopy is also useful for obtaining samples to rule out candidal infection.

Positioning

Patients undergoing laparoscopic myotomy are placed in a modified lithotomy position. A beanbag is placed, and the arms are tucked at the sides. The surgeon stands in between the patient’s legs, and the assistant usually stands on the patient’s left side. Monitors are placed at the head of the bed, and one is placed on the right side of the patient so that the assistant can see the screen.

After undergoing surgery, the patient is kept on NPO (nil per os) status until a barium swallow is completed. This imaging study is done to ensure that the operation did not cause a perforation. Typically, patients receive liquids on the evening of their operation and then are advanced to a soft diet and discharged the following day. Nausea must be treated aggressively with antiemetics. Patients are advised to avoid strenuous activity and heavy lifting for 4-6 weeks. Most patients resume normal activities within 1-2 weeks and a regular diet within 2-6 weeks.

Ernst Heller first described the two-cardiomyotomy (one anterior and one posterior) technique along the esophagogastric junction (EGJ) for achalasia in 1914. This technique has since been modified so that only an anterior myotomy is performed. Heller myotomy provides excellent results and relief of dysphagia in 90-95% of patients.[11, 8]

Traditionally, surgery was accomplished via a transthoracic or transabdominal approach. Each was associated with the morbidity of a major open procedure, often with expected hospital stays of 7-10 days. For this reason, patients commonly were treated by by means of less invasive therapies such as pneumatic dilatation, despite the superior long-term results from surgical myotomy.[18]

In the early 1990s, as minimally invasive techniques developed, surgical treatment came to be more widely accepted. The thoracoscopic approach was first described in 1991. This minimally invasive approach decreased postoperative pain and shortened hospital stays without compromising the relief of dysphagia.

In the mid-1990s, multiple factors led to a shift from the thoracoscopic to the laparoscopic approach, including the following:

• With the increase in the number of laparoscopic fundoplications being performed, surgeons became more adept at laparoscopically operating on and around the esophageal hiatus
• Many recognized that extending the myotomy well onto the stomach was critical for consistent and durable relief of dysphagia
• The incidence of postoperative reflux was high with the thoracoscopic approach even with limited gastric myotomy; this highlighted the need for a fundoplication, which is much easier to perform laparoscopically than via the chest

Additionally, laparoscopy avoids the need for single-lung ventilation with a double-lumen endotracheal tube and tube thoracostomy. The laparoscopic approach has been found to be superior to both open and thoracoscopic procedures with respect to complications, morbidity, mortality, length of hospital stay, relief of dysphagia, prevention of postoperative reflux, and operating time.

University of Washington experience

At the University of Washington (UW), surgeons converted from a thoracoscopic to a laparoscopic Heller myotomy in 1994 for two distinct reasons. First, the surgeons recognized that a limited gastric myotomy (0.5-1.0 cm) failed to protect the patient from gastroesophageal reflux (GER). In fact, when pH monitoring was performed, 80% of patients had pathologic reflux. Second, 17% of patients in their series returned with recurrent dysphagia, and half of them responded to extension of the gastric myotomy between 1.5 and 2.0 cm via the laparoscopic approach.

Between 1994 and 1998, 52 patients underwent laparoscopic myotomy with this longer gastric myotomy, yielding excellent improvement in dysphagia in over 90%. Still, occasional patients had inadequate relief or recurrence of dysphagia, some of whom improved with further extension of the gastric myotomy.

Therefore, the UW surgeons began extending the gastric myotomy a full 3 cm in 1998.[19] They also began performing a Toupet, rather than a Dor, fundoplication. They felt that an anterior fundoplication was more difficult with a 3-cm cardiomyotomy and suspected that the 270° posterior Toupet would provide better control of reflux. A comparison of the two approaches confirmed that an extended myotomy with Toupet fundoplication (EM/Toupet) more effectively obliterated the lower esophageal sphincter (LES) than the shorter myotomy with Dor fundoplication (SM/Dor). 

The evidence for this was a greater reduction in the residual LES pressure (9.5 vs 15.8 mm Hg), as well as better, more durable relief of dysphagia. Dysphagia was both less frequent (once a month vs once a week, on average) and less severe (3.2 vs 5.3 on a 10-point visual analogue scale) in the EM/Toupet group. Most important, in the subsequent 7 years, no patient required surgical intervention for recurrent dysphagia. Furthermore, this complete obliteration of the LES did not result in more reflux; the mean distal esophageal acid exposure was equivalent in the two groups (EM/Toupet, 6.0%; SM/Dor, 5.9%).

Pneumoperitoneum is usually established with a Veress needle and the use of an optical trocar. For a myotomy, four working ports are inserted under direct vision. The port for the camera is placed about 10-12 cm inferior to the left upper quadrant port and about 4-6 cm left of the midline. The remaining ports include a 5-mm trocar inserted in the right upper quadrant, a 10-mm trocar in the left lower quadrant and a 10-mm trocar in the right lower quadrant to retract the liver.

After the ports have been inserted, the patient is usually placed in a steep reverse Trendelenburg position. A 10-mm 30° angled camera is used.

The initial approach involves dividing the left phrenoesophageal and phrenogastric ligaments, allowing exposure of the left crus. Next,  the gastric fundus is mobilized to create a tension-free fundoplication. An ultrasonic dissector (eg, Autosonix; United States Surgical, Norwalk, CT) is used to divide the short gastric vessels, beginning at the inferior pole of the spleen and continuing superiorly to the previously exposed left crus.

After the left phrenoesophageal ligament is divided, the gastrohepatic ligament is incised. The right and anterior phrenoesophageal ligament and peritoneum overlying the anterior abdominal esophagus are divided, with care taken not to damage the underlying anterior vagus nerve. When a posterior Toupet fundoplication is planned, a posterior esophageal window is created. During this step, the posterior vagus nerve should be visualized and protected. If an anterior fundoplication is performed, only the anterior esophagus requires full exposure.

Adequate mediastinal esophageal mobilization is crucial for a long esophageal myotomy and tension-free fundoplication. A Penrose drain may be placed around the EGJ and used to retract the esophagus caudally and laterally during hiatal and mediastinal mobilization. To clear a path for the myotomy across the EGJ, it is useful to resect the cardioesophageal fat pad to the left of the anterior vagus nerve while simultaneously mobilizing the vagus from the esophagus. This allows a straight plane for performance of the myotomy.

Excellent visualization and exposure are essential to performing a safe and adequate myotomy. A lighted 52-French bougie is placed into the body of the stomach, serving both to illuminate the esophagus and muscle layers and to provide a stable platform for performing the myotomy. The myotomy is begun approximately 3 cm below the EGJ, and an L-shaped hook electrocautery device is used to divide the muscle fibers.

During the myotomy, electrocautery should be avoided unless absolutely necessary. Individual muscle fibers are divided by hooking them and applying gentle upward traction. Bleeding from the muscle or submucosa is controlled with pressure and time. These steps are important to avoid delayed perforation from unrecognized thermal mucosal injury.

Progressive division of the longitudinal and then the circular muscle layer is performed as the myotomy is carried superiorly, 6-8 cm above the EGJ. Once the circular muscles are divided, a mucosal plane is reached with smooth, white, bulging mucosa (see the image below). Thus, the entire myotomy spans approximately 6-10 cm (3 cm below to 6-8 cm above the EGJ). The most difficult dissection involves the 3-cm myotomy on the stomach, where the plane of dissection becomes blurred with intervening sling muscular fibers and the underlying gastric mucosa is thinner, increasing the risk of perforation.

Mucosal perforations are repaired with a fine (4-0 or 5-0) absorbable monofilament suture and rarely require further intervention. In cases with a perforation, performing an anterior (Dor) fundoplication is prudent to buttress mucosal repairs and prevent leakage or fistula formation. Endoscopy can be used to evaluate the completeness of the myotomy and check for a missed perforation.

After satisfactory cardioesophageal myotomy, a Toupet fundoplication is performed. The posterior fundus of the stomach is brought around the esophagus and secured to the right crus and the right cut edge of the myotomy. In a similar (in fact, mirror-image) fashion, the anterior fundus is sutured to the left crus and the left edge of the myotomy. Rarely, patients with large hiatal hernias require crurapexy closure of the hiatus.

Ideal length of myotomy

In general, the length of the myotomy should not exceed 6-8 cm. Sometimes, one may extend the myotomy on the proximal stomach for 2-3 cm. If a longer myotomy is performed, aperistalsis will occur, and the patient will develop severe bloating and dysphagia, which often are not reversible.

Choice of laparoscopic vs thoracoscopic approach

First, it should be understood that myotomy can be performed via either the abdomen or the thorax. The choice of approach depends on the surgeon’s training and personal preference. There is no good evidence for the superiority of one technique over the other with regard to the end result, but there are various technical differences between the two, as follows:

The first involves patient positioning. With the laparoscopic approach, the patient is placed supine, whereas with the thoracoscopic approach, the patient must be placed in the lateral decubitus position and be firmly protected by a bean bag to prevent a fall. Nerve compression injuries are also more likely with the thoracoscopic procedure. In addition, the patient needs a dual-lumen endotracheal (ET) tube, which can often add an extra 30-60 minutes to the procedure. Furthermore, there is always the risk of dislodgment of the ET tube during surgery, which technically complicates the procedure.

A second difference relates to specialty preferences. Thoracic surgeons generally prefer video-assisted thoracoscopic surgery (VATS), whereas general surgeons prefer the abdominal approach. However, if the patient is undergoing other procedures concomitantly, such as cholecystectomy, then an abdominal approach is preferred.

A third difference has to do with certain technical difficulties specifically associated with thoracoscopy. In some cases, identifying the distal LES via the thoracoscopic approach can be difficult, especially in obese individuals. In addition, extending the myotomy to the proximal stomach can also be problematic via thoracoscopy. For patients who have undergone multiple abdominal procedures, the presence of adhesions may make a thoracoscopic approach more practical and safer.

A fourth difference concerns the degree of postoperative pain and morbidity. The pain after a laparoscopic procedure is significantly less than that after a thoracoscopic one, and if by chance the procedure must be converted to an open operation, a thoracotomy is associated with much higher morbidity than a celiotomy is.

A fifth difference is that adding a reflux procedure is also slightly more difficult via the thoracoscopic approach.

In conclusion, as surgeons become more experienced with minimally invasive procedures, it is to be hoped that they may become skilled in both laparoscopic and thoracoscopic approaches to myotomy. No matter which procedure the surgeon elects to perform, the key is to ensure patient safety.

For patients who have recurrence of symptoms, those whose myotomy was inadequate, or those who underwent a prior thoracoscopic myotomy, laparoscopic surgery is the procedure of choice. The procedure allows extension of the myotomy and performance of an additional reflux procedure if required.

To ensure that the dysphagia caused by achalasia is effectively relieved, complete division of the LES muscles is necessary.

Thoracoscopic long myotomy has been performed with moderate success in patients with diffuse esophageal spasm.[20]

It must be kept in mind that a thoracic approach to myotomy does not allow complete extension of the myotomy to the cardia, which is a common reason for recurrence of dysphagia. Redo surgeries are generally more difficult and do require advanced laparoscopic skill and a good understanding of the abdominal and thoracic anatomy.

If the patient has had a myotomy and has recurrence but is not a candidate for surgery, pneumatic dilatation is another noninvasive option. Botulinum toxin has been used to treat achalasia and is an option for patients who are poor candidates for surgery. It should not be used in good surgical candidates, because it induces severe fibrosis and makes surgery difficult. The intense fibrosis often lasts 6-12 months.

With the advent of minimally invasive surgery, laparoscopic Heller myotomy now is the first procedure of choice for most patients.[21, 22, 23]

Robot-assisted surgery has also been used to treat achalasia.[24] Robotic surgery can perform both an anterior reflux procedure and a myotomy without assistance. The chief advantages of robotic surgery include greater flexibility, better visualization, increased range of motion of instruments, and ease of fine manipulations in tiny spaces.

The anatomy of the esophagus lends itself well to robotic surgery because the approach is direct and allows the robotic arms a full range of mobility and flexibility. Once the instruments are inserted, not much maneuvering is required except fine dissection.

To date, however, there have been no studies comparing robotic surgery with manual laparoscopy in the treatment of achalasia. The definitive feature of robotic surgery in this setting is its prohibitively high cost.

Early

Perforation of the esophagus is known to occur in 1-5% of cases. The vast majority of perforations are identified in the operating room and easily repaired with minimal morbidity and no affect on the relief of dysphagia. This is vastly different from the morbidity associated with esophageal rupture that occurs following balloon dilatation for achalasia

Additional complications of surgery seen in 3% of patients include bleeding, pneumothorax, wound infection, and ileus. The pneumothorax rarely requires treatment except for observation with serial chest radiographs. Other rare complications include splenic injury and injury to the vagus nerve.

Late

Late complications from the surgery include recurrent dysphagia. Other common complications include incomplete myotomy, scarring in the hiatal region, and stricture formation.