Minimally invasive surgery for large hiatal hernia

Abstract The majority of large hiatal hernias are paraesophageal hiatal hernias (PEH). Once prolapse of the stomach to the chest cavity reaches a high degree, it is called an intrathoracic stomach. More than 25 years have elapsed since laparoscopic surgery was carried out as minimally invasive surgery for PEH. The feasibility and safety thereof has nearly been established. PEH may cause serious complications such as strangulation and perforation. The outcome of elective repair of PEH is better than emergent repair, so we should carry out elective repair as much as possible. Although not a major clinical problem, following PEH repair the rate of anatomical recurrence increases with age. In order to reduce the recurrence rate, mesh reinforcement by crural repair has been widely performed. Although this improves the short‐term outcomes, the long‐term outcomes are unclear. For PEH repair, fundoplication and gastropexy are believed desirable. We should select the procedure associated with a lower incidence of dysphagia and so on following surgery. While relaxing incision is useful for primary tension‐free closure, it has not contributed to improvement in the recurrence rate.


| INTRODUC TI ON
for PEH. Although the high recurrence rate 2 was initially a problem, there have been more and more reports on its feasibility and safety. 3,4 Most large hiatal hernias (LHH) are PEH. Once prolapse of the stomach to the chest cavity becomes manifested in PEH, it is called an intrathoracic stomach (ITS). Upside-down stomach (UDS) is ITS with nearly 100% of the stomach prolapsed. In this article, we clarify the definition of LHH and ITS and provide a review on minimally invasive surgery for LHH from several viewpoints.
There is no clear international definition for LHH. It is defined by articles in terms of the extent to which the stomach is prolapsed to the chest cavity ( Figure 1). For example, one may define LHH as a stomach prolapse of 50% or more, which is categorized into 50% or more prolapse, 75% or more prolapse, and 100% prolapse. In this case, LHH is equivalent to PEH. On the other hand, SE is used when the esophagogastric junction is located 5 cm or more closer to the rostral side from the normal anatomical position 5 and there are complications such as esophageal ulcer and stenosis as well as fibrosis of the tunica muscularis esophagi. Some argue that SE is carried out when sufficient length of the abdominal esophagus cannot be assured even if the esophagus in the mediastinal space is sufficiently detached during surgery. 6-8 ITS means a prolapse of a substantial part of the stomach to the chest cavity, which is similar to LHH. GHH has almost the same meaning as LHH. Some assert that a prolapse of 50% or more of the stomach to the chest cavity is called GHH. 9 Large PEH and giant PEH therefore mean a prolapse of 1/3 to 1/2 or more of the stomach to the chest cavity. [9][10][11] UDS means prolapse of nearly the entire stomach. However, it is necessary to confirm the definition by articles because it does not necessarily indicate prolapse of the entire stomach.
In summary, most analysis targets on LHH are PEH. Studies on LHH target subjects with a prolapse of approximately one-third or more of the stomach to the chest cavity. Many studies on ITS target subjects with a prolapse of 50% to 75% or more of the stomach to the chest cavity. 12,13 Studies on UDS target subjects with a prolapse of 75% or more of the stomach to the chest cavity, 13 some of which are limited to only 100%. Regarding PEH, the extent of prolapse of the stomach to the chest cavity is as follows: UDS ≥ ITS ≥ LHH ≒ GHH ( Figure 2).

| SURG I C AL IND IC ATI ON S FOR LHH
According to the guidelines by SAGES in 2013, 10 "All symptomatic PEHs should be repaired, particularly those with acute obstructive symptoms or those that have undergone volvulus." Many reports support this statement. 11,14 There is no disputing the surgical indication for symptoms of gastric outlet obstruction and torsion.
The statement "all symptomatic PEHs should be repaired" indicates the importance of the symptoms of PEH patients. The presence or absence of symptoms is controversial. There have been reports on relatively low incidence of symptoms such as heartburn 26%, postprandial chest discomfort or chest pain 23%, dysphagia 21%. 6 Carrott et al divided 270 large-PEH patients in accordance F I G U R E 1 Paraesophageal hiatal hernia. Classification of paraesophageal hiatal hernia according to the degree of gastric prolapse to the chest cavity F I G U R E 2 Concept of paraesophageal hiatal hernia. Regarding paraesophageal hiatal hernia, the extent of prolapse of the stomach to the chest cavity is as follows: upside-down stomach ≥ intrathoracic stomach ≥ large hiatal hernia ≒ giant hiatal hernia with the proportion of ITS into four groups: <50%; 50% or more; 75% or more; and 100%, then examined the symptoms in detail. 15 The occurrence rates of the symptoms were as follows: heartburn: 76%-56%; regurgitation: 54%-38%; chest pain: 48%-50%; and dysphagia: 42%-54%. UDS comes with complications such as strangulation, stomach obstruction, acute bleeding from ulceration, leading to stomach necrosis, perforations and mediastinitis. 16 Fifty percent or more of these patients have GERD symptoms. 17 Going forward, further examination is necessary of the degree and frequency of symptoms.
Because LHH compresses the heart and lungs, it may cause a decline in cardiac function and respiratory function. However, it is difficult to conclude that LHH causes symptoms such as chest pain, palpitations, respiratory discomfort, and coughing. There have been reports on improved cardiac function by HH repair, along with reports on both-side heart failure due to ITS. Carrott et al examined the respiratory function before and after surgery among 120 PEH patients, reporting that respiratory function was improved after surgery, such as forced vital capacity, forced expiratory volume in 1 second, vital capacity, and diffusion capacity of the lungs for carbon monoxide. 18 This improvement was particularly manifested in patients aged 80 or older, patients with large hernias, and patients with decreased preoperative respiratory function. Therefore, disorders in cardiac function or respiratory function may be improved following surgery.
On the other hand, there is a statement which says, "routine elective repair of completely asymptomatic PEH may not always be indicated. Consideration for surgery should include the age and comorbidities of patients." Some argue that we should consider the possibility of volvulus for ITS and UDS involving 75% or more stomach prolapse and carry out surgery even without symptoms. 19 For ITS and UDS with a high degree of prolapse without any symptoms, we will consider age and quality of life (QOL) when it comes to surgery indication.

| OUTCOME S OF SURG ERY TRE ATMENT FOR LHH
We need to consider numerous factors when examining surgery treatment outcomes for LHH and PEH, so it is difficult to summarize the treatment outcomes.
The most important patient factors include the degree of stomach prolapse and the presence or absence of a SE. Many surgical factors are considered, including whether or not mesh should be used, the types of fundoplication and whether or not they should be used, and whether to use either emergency repair or elective repair. 11 The evaluation of outcome also differs depending on articles in the definition of recurrence, whether it is recurrence of symptoms or anatomical recurrence. While the recurrence rate of hernias is relatively high following surgery for PEH, 20-23 the hernias are often mild, so many have reported them as not being a clinical problem. 24 Consequently, the evaluation of outcomes is difficult. In this article, we evaluated the outcomes in terms of fundoplication, emergency versus elective, and mesh.

| Fundoplication
The decision on whether or not fundoplication should be carried out following PEH repair, along with what procedures should be performed, is controversial. In general, fundoplication needs to be conducted to prevent postoperative GER, with intra-abdominal gastric fixation recommended to reduce recurrence. 25 On the other hand, some argue that the merits are unclear regarding conducting fundoplication on patients without reflux, 26 while others have reported that fundoplication increased the postoperative incidence of dysphagia, which reached a maximum of 50% following PEH repair. 4 Blake et al reported that fundoplication should not be carried out on patients without a history of significant reflux, or with poor esophageal motility, SE, or debilitating comorbidities. 13 Others reported that the addition of fundoplication to ITS surgery does not contribute to QOL improvement, 27 and that there was no difference in the symptom scores, satisfaction, and use of proton pump inhibitors in accordance with the presence or absence of anti-reflux surgery (ARS). 6 The guidelines state, "Fundoplication must be performed during repair of a sliding type hiatal hernia to address reflux. Fundoplication is also important during PEH repair." It is believed that the addition of ARS to anatomical repair has greater merit. Heartburn, a typical symptom of GERD, was present in 26% to 76% of patients. 6,15,28 Therefore, we believe ARS should be added for patients exhibiting GER symptoms prior to surgery.
Although the latest data show that 90% or more of the surgeries for PEH in the USA are laparoscopic surgery, 29 whether or not laparoscopic surgery is optimal remains controversial. The Belsey Mark IV (BM-IV) method, a transthoracic procedure, results in a high symptom disappearance rate. 12 Laan et al 30 conducted a retrospective study by matching 118 patients to the laparoscopic Nissen method and BM-IV, respectively. Although the recurrence rate and surgery satisfaction were equivalent, the occurrence rate of esophageal leak and the rate of re-surgery were higher in the Nissen group (6.8% vs 0%, 9.3% vs 2.5%, respectively). Laan et al stated that the BM-IV method is more desirable for large PEH (Table 1). 30 New facts may be found if thoracoscopic surgery is carried out going forward.
The fixation method of the stomach, either by posterior fixation or anterior fixation, is also open to question. Hill proposed the Hill method from the idea that maintaining cardiophrenic angles is essential for the control of GER. 31 Park et al compared the cases that underwent laparoscopic Hill surgery for PEH and could be followed up for a long term with cases that underwent laparoscopic Hill surgery for GERD during the same period, reporting there was no difference in the symptoms between the two groups (Table 1). 32 Although there was no mention of the recurrence rate, the satisfac- abdominal wall. The result was that all cases became free of symptoms and had no recurrence. 33 Broeders et al 34

| Mesh reinforcement
The usefulness of mesh is controversial. There are two statements on it in the guidelines. One is, "The use of mesh for reinforcement of large hiatal hernia repairs leads to decreased short-term recurrence rates." Although mesh involves complications, it reduces short-term recurrence rates. 8,40 The other statement is, "There are inadequate long-term data on which to base a recommendation either for or against the use of mesh at the hiatus." Recently, a report using the data from a period of 48 months following surgery indicated that the use of mesh decreased the recurrence rate.
Mesh may involve serious complications. 17,41,42 Typical complications include esophageal erosion and penetration, along with increased risk of infections. 18 Fatal complications reportedly include strangulation of re-herniated stomachs through a narrowed hiatus reconstructed with mesh and aortal bleeding. Surprisingly, prosthetic mesh reinforcement was reported to require re-surgery for 23 of 28 patients and esophagectomy for seven patients. 41 It was pointed out that the reason for this high rate of complications included two aspects: the procedure of mesh indwelling; and the material of the mesh. Moreover, when the opening of the hiatus esophagus is large and crural repair cannot be performed, using mesh to bridge the hiatal defect may lead to serious complications. 42 In addition, the suture and tacking during mesh fixation may involve serious complications such as cardiac tamponade. Recently, there have been fewer reports on serious complication compared to the past. 40,43,44 It has also been reported that not using prosthesis mesh resulted in a low recurrence rate and good treatment outcomes. 11 During the early 2000s, there were several RCTs but no reports on mesh-related complications. 21

| Emergency surgery versus elective surgery
Paraesophageal hiatal hernias involve complications such as gastric perforations, bleeding, and necrosis due to torsion. 47 The occurrence rate of complications is relatively high without treatment. 6  The majority of reports recommend elective surgery. 13.28 Those operating should be skilled and experienced surgeons. 15 Surgeries in experienced centers reportedly resulted in low morbidity.

LHH often involve an open and large hiatus esophagus. Particularly
for PEH, hiatus reefing often involves excessive tension. Mesh reinforcement after reefing with too much tension results in a high recurrence rate of hernia. 53 Therefore, we perform treatment to relax this tension by making a relaxing incision for these cases. [54][55][56][57][58][59] However, there have been few reports on relaxing incisions so evaluations on the incision site and the effects thereof are insufficient.
The criteria for making a relaxing incision have not been estab- lished as yet. It is used when bringing the left and right crus closer during surgery and there is too much tension thereon. In Western countries, it is common to make a relaxing incision between the right crus and the inferior vena cava, a reportedly simple procedure. [53][54][55][56]58 When the site at which a relaxing incision is to be made has inadequate intensity, is scarred, or the distance between the inferior vena cava and the right crus is close, the relaxing incision should be made on the left side of the hiatus esophagus, but it may be placed on either side when the lateral incision cannot result in adequate relaxation. [53][54][55][56]58 On the other hand, Yano et al made the incision on the left side to avoid injuring the inferior vena cava. 57 For making a relaxing incision on the right side, attention should be paid to avoid injuring the anterior crural vein or the thoracic duct.
Make the incision along the right crus toward the right chest cavity.
Regarding the left side, avoiding injuring the left phrenic nerves is essential. While Yano et al made an incision along the left crus, approximately 1 to 2 cm from the lateral margin of the left crus, it is common in Western countries to make an incision between the left crus and the seventh rib, sometimes reaching the lateral side beyond the spleen to obtain sufficient relaxing effects. 53,57,58 After the incision, hiatal reinforcement using mesh is added. From the above, while making a relaxing incision is useful for primary tension-free closure during surgery when there is too much tension during crural repair, it has yet to contribute to improvement in the recurrence rate.

| COLLIS G A S TROPL A S T Y
SE arises from chronic acid reflux leading to fibrillation and constriction of the esophagus. 6 While the incidence of SE was reportedly 1.53% among GERD patients and 11.87% among PEH patients, 25 it has also been reported that severe transmural esophagitis and fibrosis resulting in true esophageal shortening is a very rare consequence. 17  These reports showed good outcomes as follows: mortality 0%-1.7%; morbidity 8%-28%; postoperative dysphagia 0%-37%; postoperative reflux symptoms 1.9%-28%; and anatomical recurrence 2.5%-16.6%, with a satisfaction level of 93%-98%.
From the above, the CG is effective when it is difficult to ensure an intra-abdominal esophagus.
This article summarized the current state of ARS, as it may be carried out going forward for large PEH, CG, and redo ARS, in which it is difficult to carry out laparoscopic surgery.

| CON CLUS ION
The feasibility and safety of laparoscopic repair for LHH and PEH have been nearly established. Although the outcomes of elective repair are obviously better than emergency repair, attention should be paid to performing elective repair on patients with no symptoms, taking into consideration their age and complications. Although not a major clinical problem, following PEH repair, the rate of anatomical recurrence increases with age. Although it has been a long time since the clinical application of mesh, the long-term effectiveness of mesh remains controversial. We anticipate an early conclusion to this problem by increasing the rate of follow-up as much as possible.

ACK N OWLED G EM ENT
We thank Dr. Hoshino and Dr. Masuda for helping with the article search.
TA B L E 2 Surgical outcomes by the location of the relaxation incision