A myotomy as surgical treatment of achalasia was first described by Heller in 1914 [9]. The original approach, consisting of two trans-abdominal extra-mucosal myotomies on both the anterior and the posterior esophageal wall, was then modified in 1923 by Zaaijer who performed only a myotomy on the anterior wall of the esophagus [10].

During the 1960s and 1970s, a short esophageal myotomy without an antireflux procedure was performed through an open approach, either left transthoracic or transabdominal. The aim of a short myotomy was to treat dysphagia avoiding gastroesophageal reflux For instance, Ellis [11] reported in 1993 his 22-year personal experience with transthoracic short myotomy (only 5 mm onto the gastric wall) without an antireflux procedure in 179 achalasia patients. An overall improvement over a mean postoperative follow-up period of 9 years was reported in 89 % of patients, with no significant deterioration over time. Only nine (5 %) patients experienced poor results with marked gastroesophageal reflux symptoms, suggesting that a short transthoracic myotomy without a wrap was associated with relief of dysphagia in most cases and very low incidence of symptomatic gastroesophageal reflux. Others reported similar results [12, 13].

The open trans-abdominal approach without an antireflux procedure was mostly used in Europe and South America [14–16]. Excellent to good outcomes in terms of relief of dysphagia were reported in 80 to 95 % of patients, while the incidence of postoperative reflux symptoms ranged between 8.5 and 22 %. The trans-abdominal myotomy apparently resulted in a significantly higher incidence of postoperative gastroesophageal reflux than the transthoracic myotomy,. A longer myotomy onto the gastric wall, division of the phreno-esophageal ligament, and the more extensive mobilization of the esophagus were the suggested mechanisms to explain the higher incidence of postoperative gastroesophageal reflux. However, the results of the studies that assessed the occurrence of postoperative reflux were based on evaluation of symptoms only, thus underestimating the real incidence of reflux [17]. In fact, when an objective evaluation by 24-h pH monitoring was performed the incidence of postoperative reflux was significantly higher after a short myotomy. For instance, Streitz et al. assessed the gastroesophageal function by esophageal manometry and 24-h pH monitoring in 14 achalasia patients undergoing a short myotomy without an antireflux procedure [18]. They found that lower esophageal sphincter (LES) pressure decreased from a preoperative mean of 26.7 mmHg to a postoperative mean of 14.6 mmHg, and that the esophageal acid exposure was pathologic in four patients (28.6 %). By multivariate analysis, esophageal acid exposure correlated only with the value of residual LES pressure.

The addition of a partial anterior fundoplication to a long trans-abdominal myotomy with the goal of providing relief of dysphagia and minimizing the risk of postoperative pathologic gastroesophageal reflux was proposed by Dor in 1962 [19]. Since then the evidence supporting this strategy rapidly increased [20–26]. For instance, Csendes reported the long-term outcome in 100 achalasia patients treated by an anterior 6-cm myotomy (extending onto the gastric wall no more than 5–10 mm) associated with anterior fundoplication [22]. With a mean follow-up of 6.8 years in 92 of the 94 patients, occasional postoperative dysphagia was experienced by 8 % of patients only. In three patients, squamous esophageal carcinoma developed 5–9 years after surgery. Pathologic gastroesophageal reflux was present in 19 % of patients undergoing 24-h pH monitoring.

Bonavina et al. evaluated 193 achalasia patients who had undergone transabdominal Heller myotomy (8-cm long on the esophagus and 2-cm long on the stomach) and Dor fundoplication as primary treatment modality [23]. With a median follow-up period of 64.5 months (range, 12–144 months), good to excellent results were reported in about 94 % of patients, recurrent dysphagia occurred in 3.6 % of patients, and abnormal acid exposure at 24-h pH monitoring was found in only about 9 % of patients tested.

In conclusion, the evidence shows that both transthoracic and trans-abdominal myotomies are effective in the relief of dysphagia; however, a trans-abdominal myotomy with a partial anterior fundoplication is associated with significantly reduced postoperative pathologic gastroesophageal reflux rates.

In the early 1990s, minimally invasive surgical approaches were developed for the treatment several abdominal diseases including achalasia [27]. The first minimally invasive esophageal myotomy in the United States was performed with a left thoracoscopic approach in 1991 (Fig. 8.1). Pellegrini et al. published in 1992 the short-term outcomes in the first 17 achalasia patients after either thoracoscopic (n = 15) or laparoscopic (n = 2) myotomy [2]. The patient undergoing a thoracoscopic myotomy was placed in the right lateral decubitus position after insertion of a double lumen endotracheal tube to selectively intubate the right main stem bronchus. Two 5-mm trocars and two 10-mm trocars were used. Under endoscopic guidance, the myotomy was started on the esophageal wall at a point midway between the inferior pulmonary vein and the diaphragmatic hiatus and was extended distally for about 5 mm onto the gastric wall (reproducing the Ellis’ procedure) until wide patency of the lumen at the level of the gastroesophageal junction was evident at endoscopy. Then, the edges of the muscular layers were separated by blunt dissection; a chest tube was placed at the end of the procedure.

A small intraoperative mucosal laceration was reported in two patients; in both cases, conversion to open surgery was needed to suture the defect. A soft diet was resumed on postoperative day 2 in all patients undergoing minimally invasive surgery, and they were all discharged on postoperative day 3. No postoperative morbidity or mortality was reported. Postoperative discomfort was only due to the chest tube that was removed after 24–48 h. The first three patients who were treated by thoracoscopic myotomy had no relief of dysphagia: the reason was a myotomy that was not carried far enough distally onto the gastric wall. All three patients underwent a second myotomy (one by open trans-abdominal approach and two by laparoscopy), with complete relief of dysphagia in two patients. At the end of follow-up, excellent to good results in terms of swallowing status were achieved in 82 % of patients. A postoperative 24-h pH monitoring was performed in four patients 1–13 months after surgery, showing pathologic acid exposure in 60 % of them.

Since an antireflux procedure was deemed not necessary when the myotomy was performed through the chest because there was no disruption of the antireflux barrier [28], the left thoracoscopic myotomy became quickly the recommended minimally invasive approach for the surgical treatment of achalasia patients. The laparoscopic approach was reserved for patients with a previous myotomy or for those who had already a left thoracotomy [2]. However, the evidence showing safety, feasibility and significantly better early and late outcomes after LHM than left thoracoscopic myotomy rapidly increased in the late 1990s [29–43]. LHM and partial fundoplication achieved reduced postoperative pain and discomfort, shorter hospital stay, better relief of dysphagia, and lower incidence of postoperative gastroesophageal reflux than thoracoscopic myotomy (Figs. 8.2 and 8.3). For instance, Patti et al. compared the outcomes in 60 achalasia patients treated by thoracoscopic myotomy (30 patients) or LHM plus anterior fundoplication (30 patients) [33]. Median hospital stay was shorter in the laparoscopic group than in the thoracoscopic group (42 h versus 84 h, respectively). Good to excellent results in terms of resolution of dysphagia were reported in 87 % of thoracoscopic myotomy group patients and 90 % of LHM group patients. A postoperative 24-h pH monitoring was obtained in ten patients in each group: abnormal reflux was found in 60 % of patients after thoracoscopic myotomy and in 10 % only of patients after LHM. Stewart et al. [42] retrospectively reviewed the intraoperative outcomes and postoperative symptoms in 24 achalasia patients treated by thoracoscopic myotomy and 63 patients treated by LHM and partial fundoplication. Mean operating room time was significantly shorter and there were fewer conversions to open surgery (2 % vs. 21 %) in the LHM group than the thoracoscopic group. No postoperative leaks were recorded. Mean postoperative length of stay was significantly shorter for patients undergoing LHM. Persistent dysphagia and heartburn were reported more frequently after thoracoscopic surgery. An incomplete myotomy on the gastric wall was the main cause of persistent dysphagia in patients undergoing thoracoscopic myotomy, while the addition of a fundoplication by laparoscopy was key in preventing reflux [32, 44].

In the second half of the 1990s, several studies compared the results of laparoscopic and open trans-abdominal myotomy with Dor fundoplication [45–49]. For instance, Ancona et al. retrospectively analysed the short-term outcomes in 17 patients who had undergone LHM and 17 patients who had open myotomy [45]. Both groups of patients were similar in age, sex, symptom duration, maximum esophageal diameter, and length of follow-up. LHM took significantly longer than open myotomy. No mortality was observed, and morbidity rates did not differ between the two groups. Pain medications were less frequently requested by patients after LHM, who had a quicker resumption of gastrointestinal function, shorter hospital stay, and quicker return to daily activities. As a consequence total costs were lower after LHM. With a median follow-up of 6 months in both groups, one patient (5.8 %) in the laparoscopic group experienced recurrent dysphagia, and one (5.8 %) patient after open surgery was found to have pathologic acid exposure at 24-h pH monitoring.

Douard et al. [49] compared in a prospective and non-randomized study functional results after laparoscopic and open myotomy with Dor fundoplication: 52 were treated by laparoscopy, 30 by an open approach. Median follow-up was 51 months (range, 12–111). The evaluation included the assessment of presence and severity of dysphagia, chest pain, regurgitation and gastroesophageal reflux by using a clinical score at 3, 6, 12 months after surgery, then every year. Similar rates of excellent to satisfactory results were obtained in terms of relief of dysphagia: 92 % after LHM and 93 % after open myotomy. Median dysphagia score dropped at 3 months after surgery in both groups, with no significant changes over time. Typical reflux symptoms were experienced by 10 % of patients after LHM and 7 % of patients after open myotomy. The presence of pathological esophageal acid exposure was confirmed by 24-h pH monitoring in all symptomatic patients and in two asymptomatic patients.

In conclusion, the evidence shows that LHM achieves better early postoperative outcomes and similar long-term functional results when compared to the open myotomy, thus leading to a progressive switch in clinical practice from open to LHM. These benefits have (a) increased the number of achalasia patients referred for surgery rather than PD; (b) increased the number of patients referred for surgery without any previous endoscopic treatment; and (c) improved the surgical outcome of the procedure [1]. Transabdominal myotomy achieves better symptom control and lower incidence of postoperative gastroesophageal reflux than transthoracic myotomy. Therefore, LHM with partial fundoplication is the procedure of choice for the surgical treatment of achalasia patients [3].

More recently, new approaches, such as the LESS approach and the robotic approach have been developed aiming to further improve the surgical outcome in achalasia patients.

For instance, Barry et al. [8] reviewed the outcomes in 132 patients undergoing trans-umbilical LESS Heller myotomy and anterior fundoplication (66 patients) or conventional LHM and anterior fundoplication (66 patients) for achalasia. The operative time of the LESS procedure was significantly longer than conventional LHM; furthermore additional ports were used in 11 (16 %) LESS patients. No conversion to open surgery occurred in either group. Intraoperative and early postoperative morbidity rates were similar. Similar outcomes in symptom resolution were achieved in both groups (88 % of patients after LESS and 82 % of patients after conventional LHM).

These preliminary data are promising, however, large long follow-up studies are necessary to evaluate the real advantages of the LESS approach in terms of cosmesis, perioperative complications and functional outcomes.