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Endoscopic and Surgical Therapies for Achalasia
With an estimated annual incidence of 1 in 100,000 and prevalence of 10 in 100,000, achalasia is a rare, primary motility disorder of the esophagus, defined by absence of normal peristalsis and failure of swallow-induced relaxation of the lower esophageal sphincter (LES). The first described treatment for “cardiospasm” in the 1600s was self-dilatation with oral passage of a whale rib-bone with an attached sponge. In 1937 Lendrum proposed the pathologic mechanism of failed LES relaxation, leading to the new name of achalasia. The etiology of achalasia remains unclear, but autoimmune, viral, and neurodegenerative factors have been implicated in the development of impaired LES relaxation through loss of ganglion cells in Auerbach myenteric plexus, leading to loss of neurotransmitters, such as vasoactive intestinal peptide and nitric oxide. As the underlying mechanism for achalasia development remains unknown, current treatment options rely on disruption of the LES to relieve outflow obstruction.
Patients typically present with progressive dysphagia, volume regurgitation, and sometimes noncardiac chest pain.
Preoperative Work-Up
An upper gastrointestinal series or esophagram is the usual initial test to evaluate dysphagia, although some clinicians include endoscopy as an initial assessment. An esophagram will often demonstrate a “bird's beak” tapering of the distal esophagus, with progressive dilatation and tortuosity of the esophagus demonstrated in later stages of the disease. The definitive diagnosis requires confirmation by manometry, preferably high-resolution manometry (HRM). Endoscopy is important to rule out pseudoachalasia from an obstruction, such as cancer, and endoscopic ultrasound can be considered when suspicion for malignancy causing obstruction is high. Endoscopy frequently appears normal in early stages of the disease, as dilation of the esophageal body may not have occurred, but esophagitis from stasis and/or yeast esophagitis may be present. Later stages of disease may demonstrate dilatation of the esophageal body with tortuosity or sigmoidization. A timed barium swallow (TBS) provides objective data on esophageal emptying and is commonly used before and as follow-up after treatment for achalasia. TBS involves ingestion of 200 mL of oral contrast, with radiographs taken at baseline and then 1, 2, and 5 minutes after ingestion. The height and width of the barium column at each time period are recorded.
Achalasia Manometric Subtypes
With the advent of HRM, three manometric subtypes of achalasia have been described as part of the Chicago Classification. All three require incomplete or failed relaxation of the LES defined by integrated relaxation pressure (IRP) thresholds. Type I is consistent with the classical consideration of achalasia: incomplete or failed relaxation of the LES with no esophageal body contractility. Type II requires absence of normal peristalsis with at least 20% of swallows having panesophageal pressurization. Type III consists of absent normal peristalsis with secondary and tertiary spastic distal esophageal contractions in at least 20% of swallows. The response of these subtypes to various treatments will be discussed in the sections that follow.
Treatment Options
Surgical myotomy was initially described by Heller in 1913, and was performed as a thoracotomy with two separate 8 cm myotomies, separated by 180 degrees. The technique has undergone several modifications and now involves a single anterior myotomy with addition of a partial fundoplication to reduce the incidence of iatrogenic reflux. Pneumatic dilatation became a common treatment in the 1970s and 1980s. In the early 1990s, laparoscopic and thoracoscopic approaches to the Heller myotomy were described. Peroral endoscopic myotomy (POEM) was developed in the first decade of this century, but has roots in the 1980s. Ortega described an endoscopic myotomy in 1980, consisting of division of the mucosa and muscle of the LES with two short full thickness incisions. Despite satisfactory outcomes, the technique was not adopted, due to concern for esophageal perforation. POEM was first described by Pasricha in 2007 as a “submucosal endoscopic esophageal myotomy” in a porcine model. Inoue presented the first human experience in 2008 with four patients and coined the term “POEM.” He published a series on 17 patients 2 years later.
Laparoscopic Heller Myotomy With Partial Fundoplication
By the mid- to late-1990s, laparoscopic Heller myotomy had become the primary treatment for achalasia. The authors' practice is to keep patients on a clear liquid diet for 24 hours before surgery. The procedure requires general anesthesia and is most commonly performed in a split leg position. The procedure is performed with both arms on arm boards. As with all procedures involving the hiatus, steep reverse Trendelenburg positioning is utilized, so patients should be well secured to the operating room table. The authors' preferred positioning involves foot boards at the base of the flat padded and abducted leg boards with sequential compression devices for deep venous thrombosis prophylaxis in place. The legs are covered with a warming device and blankets, and the legs are secured to the leg boards with tape above and below the knee. The operating surgeon stands on the patient's left side, with the assistant standing between the legs ( Fig. 14.1 ).
Standard laparoscopic equipment is required. Atraumatic graspers are necessary for handling the involved tissues, needle drivers for suturing, and a liver retractor to provide adequate visualization of the hiatus. The harmonic scalpel is useful for dissection, but other devices can also be used. Myotomy can be performed with a hook (with or without cautery), laparoscopic scissors (with or without cautery), or the harmonic scalpel. Five laparoscopic ports are necessary, and they can all be 5 mm trocars. Typically, we use a single 11-mm port to allow the use of a larger 45-degree laparoscope. Finally, an upper endoscope should be available for intraoperative evaluation of the anatomy before and after myotomy, as well as perform endoscopic leak test. A bougie can be used during myotomy to better spread the muscle fibers.
Technique
There are four steps to a laparoscopic Heller myotomy: port placement and exposure, dissection of the stomach and hiatus, myotomy, and fundoplication.
Port Placement and Exposure
The setup is identical to that of a laparoscopic fundoplication. A Veress needle is used to establish pneumoperitoneum followed by camera port placement at the same site, to the left of midline and roughly between the umbilicus and the xiphoid. Other ports are placed as illustrated (see Fig. 14.1 ).
Dissection of the Stomach and Hiatus
The amount of dissection depends on the planned fundoplication for the procedure. Most commonly, we perform a partial posterior fundoplication, as described by Toupet. Further discussion of fundoplication choice is detailed in subsequent text. To prepare for myotomy and posterior partial fundoplication, the stomach must be mobilized and the hiatus completely dissected. The assistant retracts the gastroesophageal fat pad inferiorly to reduce any hiatal hernia, and the surgeon then divides the gastrohepatic ligament to expose the right crus. The mediastinum is then entered anteriorly, and the esophagus is mobilized circumferentially. The short gastric arteries are divided. To expose the esophagus for myotomy, the gastroesophageal fat pad is removed, taking care to protect the left vagus nerve.
Myotomy
A bougie is inserted transorally. The myotomy is initiated with the hook cautery, 2 cm above the gastroesophageal junction (GEJ). The myotomy should be performed with a low power setting to avoid transmission to the esophageal mucosa. The longitudinal and circular fibers are dissected off the mucosa and are divided. A fine grasper, such as the Maryland forceps, can be used to elevate the muscle on either side of the myotomy to allow passage of the hook cautery, laparoscopic scissors, or harmonic scalpel into the submucosal plane ( Fig. 14.2 ). Blunt dissection can be used to separate the muscle from the submucosa, which allows for elevation of the muscle away from the submucosa for continued proximal myotomy. The myotomy should be 4 to 5 cm onto the esophagus; bleeding muscle edges can be controlled with delicate cautery or compression. Extending the myotomy above the diaphragm should be avoided, as this can result in a diverticulum in the future. After completing the esophageal myotomy, the distal gastric myotomy is performed for a length of 2 to 3 cm with the energy device. After completing the myotomy, the muscle edges are mobilized laterally to each side to better expose the submucosa. Any remaining circular muscle fibers are divided. The bougie is removed, and an endoscope can be used to evaluate the myotomy and perform an air leak test.
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