Surgical Anatomy of Paraesophageal Hernias

Home , Aortic hiatus, Collis gastroplasty

Roman V. Petrov, MD, PhDa,b,*, Stacey Su, MDb, Charles T. Bakhos, MD, MSa, Abbas El-Sayed Abbas, MD, MSa,b

KEYWORDS Hiatal hernia Paraesophageal hernia Surgical anatomy Esophageal hiatus Gastroesophageal junction

KEY POINTS Incidence of paraesophageal hernias is increasing owing to the increased proportion of advanced age patients and clinicians’ awareness. Minimally invasive, including robotic, surgical techniques are increasing in popularity and produce excellent results. Thorough understanding of anatomic relationship in paraesophageal hernias is required for successful surgical repair regardless of the surgical approach.

NORMAL ESOPHAGEAL ANATOMY enters the chest through the thoracic inlet and is located initially in the superior and then the poste- The esophagus is a tubular organ, approximately rior mediastinum. The midesophagus deviates 25 cm long, which connects the hypopharynx to slightly to the right, usually passing behind the the stomach. Along its course, it traverses 3 left mainstem bronchus and pericardium anterior body areas: the neck, the chest, and the abdomen to the prevertebral fascia of T1 though T10 verte- (Fig. 1A). Accordingly, it is subdivided into 3 bral bodies. Both vagus nerves accompany the anatomic segments: cervical, thoracic, and esophagus throughout its course on each side. abdominal. The descending thoracic aorta is located posteri- The cervical segment of the esophagus starts at orly and to the left, whereas the mediastinal pleura the hypopharynx, from which it is separated by the drapes over both sides of the esophagus. upper esophageal sphincter, at the level of the The abdominal esophagus is a short segment of sixth cervical vertebra. The cervical esophagus ex- the organ, extending from the diaphragmatic hia- tends down to the level of suprasternal notch. It is tus at the level of T10 to the gastric cardia at the located directly behind and partially to the left of level of T11. After passing through the hiatus, the the trachea, in front of C6 and C7 vertebral bodies. abdominal esophagus deviates to the left and en- Laterally, the esophagus is surrounded by the ters the stomach, forming the gastroesophageal lower poles of the thyroid gland and the carotid junction (GEJ). The descending aorta is located sheaths. On the left side, the termination of the posterior to the GEJ, and the inferior vena cava thoracic duct can be found entering the venous is posterior and to the right. It is covered anteriorly angle at the junction of the left internal jugular by the left lobe of the liver. and subclavian veins. In cross-section, the esophagus has 3 layers The thoracic esophagus extends from the (mucosa, submucosa, and muscularis propria) suprasternal notch to the diaphragmatic hiatus. It

Dr. Abbas received honoraria from Boston Scientific and Intuitive. No disclosures for other authors. a Department of Thoracic Medicine and Surgery, Division of Thoracic Surgery, Lewis Katz School of Medicine at Temple University, 3401 North Broad Street C-501, Philadelphia, PA 19140, USA; b Department of Surgical Oncology, Fox Chase Cancer Center, 333 Cottman Avenue C-312, Philadelphia, PA 19111, USA * Corresponding author. Department of Thoracic Medicine and Surgery, Division of Thoracic Surgery, Lewis Katz School of Medicine at Temple University, 3401 North Broad Street C-501, Philadelphia, PA 19140. E-mail address: [email protected]

Thorac Surg Clin 29 (2019) 359–368 https://doi.org/10.1016/j.thorsurg.2019.07.008

1547-4127/19/Ó 2019 Elsevier Inc. All rights reserved. thoracic.theclinics.com Downloaded for Anonymous User (n/a) at Second Military Medical University from ClinicalKey.com by Elsevier on February 15, 2020. For personal use only. No other uses without permission. Copyright ©2020. Elsevier Inc. All rights reserved. 360 Petrov et al

Fig. 1. Anatomy of the esophagus and GEJ. (A) Position of the esophagus, with its locations in the neck, chest, and abdomen. (B) Diaphragm, esophageal hiatus and gastroesophageal junction.

surrounded by the adventitia. After crossing nodes. There is significant overlap in the lymphatic through the hiatus, the esophagus is enveloped drainage between these segments. by the visceral peritoneum, forming a serosa. The The intrinsic nervous system is formed by the muscularis propria, formed in the proximal third submucosal and the intramuscular neural plexi. of the esophagus by striated muscle, is replaced Innervation to the esophagus is supplied by both by smooth muscle in the distal esophagus. It con- vagus nerves, providing the parasympathetic con- sists of an inner circular layer and outer longitudi- trol of esophageal wall motility, the esophageal nal layer. The circular muscle fibers are arranged sphincters, and glandular secretions. Sympathetic in a helical fashion, sometimes giving rise to a innervation is provided by the sympathetic chains corkscrew appearance in many motility and is mostly responsible for vasomotor effects disorders.1 and pain sensation. The vagus nerves arise in the The blood supply to the esophagus is segmental. medulla oblongata as the tenth cranial nerves The cervical esophagus is supplied by branches of and after exiting the skull base run on each side the inferior thyroid arteries, whereas the thoracic of the esophagus. They enter the chest via the esophagus is supplied by small aortoesophageal thoracic inlet and travel caudally along the esoph- arteries, in addition to branches from the bronchial agus to the hiatus. Because of the embryologic and superior phrenic arteries. The abdominal clock-wise rotation of the lower foregut in the esophagus receives blood supply from branches abdomen, the left vagus nerve becomes anterior, of the left gastric artery, the splenic artery, and whereas the right vagus nerve lies posteriorly.1,2 the left inferior phrenic artery. Venous drainage forms a submucosal plexus, draining the cervical STOMACH segment through the inferior thyroid veins and the thoracic esophagus through the azygos system The stomach is a J-shaped saccular expansion of into the superior vena cava. The lower thoracic the foregut, serving as a reservoir for the ingested and abdominal esophagus is drained into the portal food at the beginning of the digestive process system via the gastric veins. In cases of portal hy- (Fig. 2A). It receives the food bolus from the pertension, these lower esophageal veins can esophagus, via the GEJ, below the esophageal hi- dilate, forming esophageal varices. atus. It transitions into the duodenum at the pylo- The lymphatic drainage also starts at the sub- rus. On the right, the concave edge of the mucosal plexus, forming lymphatic channels that stomach is termed the lesser curvature, whereas drain into the regional lymph nodes. The deep cer- the left convex edge is called the greater curva- vical nodes receive lymph flow from the cervical ture. The peritoneal reflections, connecting the and the upper thoracic esophagus. The paraeso- lesser curvature to the liver, form the lesser omen- phageal lymph nodes of the superior and posterior tum, also called the gastrohepatic ligament. It con- mediastinum drain the thoracic segment. The tains branches of the left and right gastric arteries. lower thoracic segment and the abdominal esoph- Peritoneal reflections on the greater curvature side agus drain into the celiac and perigastric lymph form the greater omentum and are subdivided by

Fig. 2. Types of paraesophageal hernias. (A) Normal anatomy of the GEJ. (B) Type I (sliding) hiatal hernia. (C) Type II paraesophageal hernia. The GEJ is retained at the hiatus and fundus has herniated into the mediastinum through a localized defect at the phrenoesophageal membrane, with formation of peritoneal hernia sac. (D) Type III paraesophageal hernia (herniation of the GEJ and various degrees of the gastric fundus and the body into posterior mediastinum, with formation of the peritoneal hernia sac). (E) Type III paraesophageal hernia with totally intrathoracic stomach. (F) Type IV paraesophageal hernia with herniation of the other intraabdominal organs in addition to the GEJ and various degrees of the gastric fundus and the body with formation of the hernia sac. the site of the attachment into gastrophrenic, gas- diaphragm, providing a major contribution to the trosplenic, and gastrocolic ligaments. They respiratory cycle. Several important structures contain both right and left gastroepiploic branches cross the diaphragm. The inferior vena cava enters from the pancreaticoduodenal and the splenic ar- the chest through the opening in the central teries that form an arch along the antrum and the tendon and is accompanied by small branches of body of the stomach about a centimeter lateral right phrenic nerve. The aorta with the accompa- to the stomach wall. The fundus is directly sup- nying thoracic duct traverses the diaphragm plied by the branches of the short gastric vessels. through aortic hiatus between the diaphragmatic crura. The splanchnic nerves, sympathetic chains, DIAPHRAGM hemiazygos vein, and internal thoracic artery travel through an additional minor opening in the dia- The diaphragm is a complex flat dome-shaped phragm. The esophagus with both vagus nerves fibromuscular structure that separates the chest traverses the diaphragm through the esophageal from the abdomen. It has a central fibrous tendon hiatus. and muscular fibers peripherally, attaching to the lumbar vertebrae in the back, lower 6 ribs on THE ESOPHAGEAL HIATUS both sides, and xyphoid process anteriorly. Contraction of the muscular fibers results in the The esophageal hiatus is a slit-like opening in the vertical displacement of the fibrous center of the diaphragm that is formed by the thickened

bundles of the right crus and has a reverse tear- mechanisms. Proximal migration of the LES trans- drop shape. The undersurface of the diaphragm poses it into the negative pressure environment of is covered by the thin endoabdominal fascia, the chest, diminishing the pressure gradient at the which forms the phrenoesophageal ligament at GEJ and obliterating the flap valve function of the the hiatus. This ligament is a fibrotic sheath of con- angle of His. Moreover, lateral traction by the nective tissue that inserts onto the adventitia of the stretched phrenoesophageal membrane further distal esophagus, the GEJ, as well as the intraab- compromises the LES function. Misalignment of dominal esophagus (Fig. 1B). Thus, the GEJ is the LES and the crura leads to pressure applica- usually located below the esophageal hiatus and tion on a funnel-like cardia, which tends to direct is secured in position by the phrenoesophageal intragastric contents into the esophagus with the ligament.3,4 increase of intraabdominal pressure, promoting gastroesophageal reflux.1 THE LOWER ESOPHAGEAL SPHINCTER AND The transdiaphragmatic pressure gradient, ANATOMIC ANTIREFLUX SYSTEM formed by the negative intrathoracic pressure (due to elastic recoil of the lung) and the positive The thickening of the circular layer of the distal intraabdominal pressure (due to the tonic contrac- esophagus above the GEJ is called the lower tion of the abdominal wall muscles), exerts a con- esophageal sphincter (LES). The LES usually mea- stant upward push on the GEJ. The deglutition sures 2.5 to 4.5 cm in length, with the upper part process is associated with foreshortening of the lying within the hiatus and the lower part in the esophagus. These, in addition to large-volume abdomen. The LES serves as a first component of meals, distend the gastric fundus and lead to the antireflux mechanism. Although not a true stretching and weakening the LES, an effect anatomic sphincter, it is defined as a high- similar to that at the neck of an inflated balloon. pressure zone by manometry and is tonically con- Additional stressors on the phrenoesophageal lig- tracted, providing a pressure gradient between ament are associated with increased intraabdomi- the esophagus and the stomach. The short intraab- nal pressure, such as obesity, constipation, urinary dominal segment of the distal esophagus is obstruction, chronic obstructive pulmonary dis- exposed to the positive intraabdominal pressure ease with chronic cough, and job-related heavy and serves as an additional pressure barrier, aiding exertion. Restrictive lung disease may heighten the LES in its antireflux function. The crura of the the transdiaphragmatic pressure gradient owing esophageal hiatus are another component, exert- to increased negative intrathoracic pressures. ing lateral pinching of the distal esophagus, or the Impaired connective tissue integrity may also so-called pinchcock effect. In deep inspiration, play a role in developing a paraesophageal hernia. pressure increases due to crural contraction when Accordingly, paraesophageal hernias frequently transdiaphragmatic pressure gradient also in- present in elderly patients with comorbidities and creases, preventing gastroesophageal reflux.5–7 degenerative diseases. It may also be associated The third component of the antireflux mechanism with familial clustering, suggesting that genetic is the angle of His, a flap valve comprising of the factors may also be a causal factor.1,10,11 fundus, draping along the left side of the abdominal esophagus at an acute angle, which is held in place TYPES OF HIATAL HERNIAS by the phrenoesophageal ligament.8 The final physiologic mechanism for controlling reflux is the Hiatal hernias are classified into 4 types according esophageal peristalsis. Mechanical and chemical to the degree of the intrathoracic prolapse of the receptors in the distal esophagus mediate esopha- GEJ and its relationship to the herniated stomach geal clearance of intraluminal contents. Poor (Fig. 2).1,12,13 esophageal motility, in combination with acid Type I hiatal hernia is the most common type reflux, may lead to esophagitis, which could further and represents more than 95% of all cases (see impair the function and the tone of the LES.9 Fig. 2B).1,13 It is probably the first step in the con- tinuum of the progressive distention of the phre- PATHOPHYSIOLOGY OF HIATAL HERNIA noesophageal membrane and separation of the DEVELOPMENT GEJ and crural diaphragm. It is frequently termed a sliding hernia. Contrary to the common misper- Hiatal hernia occurs when a portion of the gastric ception, it is not because it goes up and down cardia prolapses into the posterior mediastinum but rather because it is a hernia that is formed by through the esophageal hiatus. This leads to the wall of the organ itself, without a hernia sac. misalignment of the LES and the crura, thus dis- Type II paraesophageal hernias form due to a rupting the protective anatomic defense local defect of the phrenoesophageal membrane,

Fig. 3. Radiologic evaluation of paraesophageal hernias. (A) Chest radiograph demonstrating retrocardiac lucency, consistent with paraesophageal hernia. (B) Esophagram, demonstrating type II paraesophageal hernia. Please note normal position of the GEJ. (C) Esophagram, demonstrating type III paraesophageal hernia. (D) Esophagram, demonstrating type III paraesophageal hernia with totally intrathoracic stomach. (E) Barium enema, demonstrating type IV paraesophageal hernia with intrathoracic colon (coronal reconstruction [left] and axial image [right]). (F) Computed tomography (CT) demonstrating type III paraesophageal hernia. (G) CT demonstrating type IV paraesophageal hernia, with totally intrathoracic stomach and colon (coronal reconstruction [left] and axial image [right]). (H) CT, demonstrating type IV paraesophageal hernia with a large posterior component and herniated retroperitoneum and pancreatic tail. (I) Esophagram, demonstrating recurrent paraesophageal hernia with posterior crural disruption, leading to small bowel herniation but normal position of the GEJ (gastric faze, showing normal intraabdominal position of the stomach [left] and intestinal faze, demonstrating transhia- tal herniation of the small bowel [right]). (J) Paraconduit hernia in a patient after previous minimally invasive esophagectomy.

Fig. 3. (continued) operated field with loss of the normal tissue planes techniques esophagectomy has likely led to an in- due to scarring. A clear understanding of the crease in the incidence of paraconduit hernias. anatomic relationship requires extensive preoper- ative workup with functional and cross-sectional RADIOLOGICAL ANATOMY imaging, manometry, and direct visualization via endoscopy (Fig. 3F). Review of the previous oper- Imaging studies are an important step in preoper- ative record is mandatory for extrapolation of the ative patient evaluation. Occasionally, the pres- anatomic relationships after a previous surgical ence of a paraesophageal hernia can be procedure. suspected on a chest radiograph, with demonstra- tion of retrocardiac air-fluid level or lucency PARACONDUIT POSTESOPHAGECTOMY (Fig. 3A). An esophagram with fluoroscopy allows HIATAL HERNIAS a thorough assessment of the anatomy, the configuration of the gastrointestinal tract, and the After esophagectomy, a neoesophageal conduit swallowing function (Fig. 3B–D, I). Computed to- (tubularized stomach or colon) traverses the dia- mography provides further assessment of the phragm. This creates a potential defect between size of the hernia and hiatal defect; configuration the conduit and the edges of the hiatus, potentially of the stomach; size and content of the hernia leading to herniation of abdominal contents into the sac, with the degree of the adjacent structures chest. These hernias can form on any side of the compression; and involvement of the other intra- conduit, although it is the left posterior aspect of abdominal organs (Fig. 3F–H, J).16–18 Additional the hiatus that is more commonly herniated studies might be indicated to assess the involve- (Fig. 3J). Because these hernias have no hernia ment of other organs (Fig. 3E). sac and the peritoneal cavity communicates directly with the pleural space, large segments of ENDOSCOPIC ANATOMY small and large intestines pass through the hiatus and translocate into the chest.14,15 Laparoscopic Endoscopy is mandatory in evaluation of all para- surgery is known to be associated with less fibrosis esophageal hernias before repair. Anatomic evalu- and fewer adhesions than traditional open proced- ation of the paraesophageal hernias during ures. The increasing adoption of minimally invasive endoscopy includes assessment of the hernia

Downloaded for Anonymous User (n/a) at Second Military Medical University from ClinicalKey.com by Elsevier on February 15, 2020. For personal use only. No other uses without permission. Copyright ©2020. Elsevier Inc. All rights reserved. Surgical Anatomy of Paraesophageal Hernias 365 size, status of the LES, and presence of complica- left triangular ligament and retracting it to the right. tions, such as strictures, Barret esophagus, or This maneuver exposes both the central tendon even tumors.19 The retroflexion endoscopic view and the esophageal hiatus of the diaphragm. provides important observation into the type and The hiatus is usually obviously dilated. The grading of the GEJ.8 In patients with paraesopha- lesser omentum is stretched over the right crus geal hernias, a Hill type IV junction is present, with and follows the lesser curvature into the medias- the extrinsic impression of the dilated hiatal open- tinum. After manual reduction of the stomach, ing along with the various degree of herniated the previously stretched phrenoesophageal mem- stomach. brane appears floppy after hernia reduction. It is Measurement of the paraesophageal hernia is grasped and opened, allowing visualization and accomplished by subtraction of the distance circumferential mobilization of the esophagus. from the incisors to the Z-line from that of the inci- This is followed by division of the phrenoesopha- sors to the hiatus. Owing to distention of the stom- geal membrane and dissection of the sac.20,21 ach by the insufflated air, most of the organ pops The esophagus is retracted anteriorly and to the back into the subdiaphragmatic position. In cases left, exposing the posterior hiatus. The crura are of large paraesophageal hernias with most of the approximated, leaving at least a 1-cm space be- intrathoracic stomach in organoaxial or mesoaxial tween the esophageal wall and the edge of the hi- rotation, it is sometimes difficult to find the hiatus atus. An antireflux procedure of choice is then and the passage into the subdiaphragmatic stom- performed before conclusion of the repair.22 ach. Any attempt at accurate length measurement in these cases can be unreliable (Fig. 4A-C). TRANSTHORACIC ANATOMY SURGICAL ANATOMY Transthoracic anatomy is usually accomplished Paraesophageal hernias may be approached from through the left chest. Video-assisted thoraco- the abdomen or the chest. The most common mo- scopic surgery (VATS) modification has not gained dality is undoubtedly laparoscopic. However, in wide adoption and there are only limited reports of 23,24 certain cases, an open laparotomy may be neces- VATS. Robotic transabdominal modification of sary. In case of multiple recurrences or a hostile Belsey repair technique has also been 25 abdomen from previous surgeries, the thoracic described. approach may be preferred. The surgeons must The patient is positioned in the right lateral decu- therefore familiarize themselves with the different bitus position and a left posterolateral thoracot- appearanceof theanatomy throughevery approach. omy is performed in seventh or eighth intercostal space. The inferior pulmonary ligament is divided ANATOMIC EXPOSURE WITH LAPAROTOMY and the lung is retracted superiorly. The descending aorta is visible in the field and the esophagus An open hiatal hernia abdominal repair is usually with the paraesophageal hernia is identified imme- performed through an upper midline laparotomy diately anterior and medial to it. The left atrium is with extension above the xyphoid process. Effec- located anteriorly to the hernia sac. Opening of tive elevation of the costal margin is required for the hernia sac allows dissection of the crura. The adequate exposure. The left lobe of the liver esophagus is mobilized sufficiently to allow covers the hiatus and is mobilized by dividing the tension-free repair.

Fig. 4. Endoscopic anatomy of paraesophageal hernias. (A) Endoscopy, demonstrating type II paraesophageal hernia on the retroflexion view. Please note normal position of the GEJ and herniation of the fundus. (B) Endoscopy, demonstrating type III paraesophageal hernia. (C) Endoscopy, demonstrating, type III paraesophageal hernia, with totally intrathoracic stomach. Please note location of gastric outlet next to GEJ due to organoaxial and mesoaxial rotation.

Fig. 5. Liver retractors. (A) Nathanson liver retractor. (B) Flexible liver retractor. (C) LiVac retractor. (Courtesy of [A] Dr. Warner W. Wang, MD, Marietta, OH; and [C] Dr. Philip Gan, Livac Pty Ltd, Warrnambool, Australia.)

MINIMALLY INVASIVE, LAPAROSCOPIC over the spleen, which may require reapplication ANATOMY of the retractor throughout the procedure. Again, the hiatus is dilated and is oval to round in The laparoscopic approach has enjoyed wide shape (Fig. 6A). The phrenoesophageal mem- acceptance owing to the benefits associated 22,26 brane is stretched and is bulging into the medias- with minimally invasive surgery. Laparoscopy, tinum, augmented by positive intraabdominal either traditional or robotically enhanced, allows a pressure of the pneumoperitoneum. The stomach, significant advantage in visualization and magnifi- unless incarcerated by adhesions, usually freely cation of the target anatomy, facilitating dissection retracts into the abdomen. Occasionally, there is and repair. With the camera usually placed in the a posterior crural diastasis, accompanied by sig- left epigastric area, the viewing trajectory is right nificant posterior component of the hernia sac. In along the esophagus, clearly depicting the hiatus, such scenario, a large volume of the retroperito- gastroesophageal junction, esophagus, and struc- 27–32 neal fat is prolapsed into the chest in the form of tures of the posterior mediastinum. a mediastinal lipoma. This can involve prolapse Exposure of the hiatus requires elevation of the of the retroperitoneal organs (pancreas and left lobe of the liver. Either a Nathanson retractor, spleen) causing the type IV hernia. placed through the subxyphoid area, or a flexible The esophagus is mobilized high into the medi- retractor, placed through right flank port, is used 13,33,34 astinum with a coaxial close-up view of camera for these purposes (Fig. 5A, B). The LiVac visualization. Mobilization starts with opening of vacuum liver retractor (Livac Pty Ltd, Warrnam- the phrenoesophageal membrane and hernia bool, Australia) has recently been introduced into sac, usually anteriorly, which allows entrance in clinical practice for this purpose (Fig. 5C). Obese to the mediastinal tissue.13,28,35 The CO2 creates patients, especially men, may have a significantly a foamy appearance of the loose connective tissue enlarged and fragile left lobe of the liver due to a of the mediastinum, with easy identification of any fatty liver and this is prone to injury and bleeding. vessels (Fig. 6B). With good visualization, mobili- This may complicate exposure of the relevant zation of the thoracic esophagus to the subcarinal anatomy. Women, in contrast, more often have a area is possible. At this point, the surgeon should thin and floppy left lobe of the liver, reaching identify the membranous airway and minimize

Fig. 6. Laparoscopic anatomy of the paraesophageal hernias. (A) Dilated hiatus with totally intrathoracic stomach. Greater curvature is visible in the hernia sac and the greater omentum draping over the hiatus. (B) Foamy appearance of the mediastinal tissue signifies the correct plane of dissection. (C) Subcarinal lymph node pocket and thoracic duct exposed along the thoracic aorta are visible during the dissection.

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