TSRA Content:
Authors: Antonio Lassaletta, MD, and David Odell, MD
Congenital Defects
Diaphragmatic Hernia of Morgagni:
The 18th century anatomist Giovanni Morgagni described a congenital anterior retrosternal diaphragmatic hernia in 1769. Rare conditions make up less than 5% of reported diaphragmatic defects. It occurs between the xiphoid process of the sternum and costochondral attachments of the diaphragm. It results from a failure of myoblast to spread over the area. Hernias commonly occur on the right side as this potential space is covered by pericardium on the left side, even though this hernia is present since birth but is more likely to manifest in adult life and so frequently as a coincidental finding on chest X-ray taken for another reason. The presentation varies from only vague fullness and cramping to obstructive in nature. Pregnant and obese patients are more symptomatic. Radiographic findings may show a mass or even a fluid level. The viscera in the sac usually include one or more of the following: colon, omentum, stomach, and small bowel. An upper gastrointestinal series or barium enema can characterize abdominal contents in the sac. Computed tomographic scanning is particularly useful and sensitive for the diagnosis.
Repair is indicated for all appropriate candidates. The repair is best done via an abdominal approach. A midline or subcostal incision will allow for excellent visualization of the hernia and its contents. Recently, laparoscopic repair has been increasingly used. After the abdomen is entered, Reduction of contents of the sac by gentle traction. Then identification of sac margin followed by resection of the sac. In the rare case of incarceration, the skin incision may be extended across the costochondral arch into the intercostal space to allow bimanual manipulation and reduction of hernia content. Direct repair is performed if there is adequate rim of diaphragm muscle around the hernia defect using heavy, non-absorbable suture placed in interrupted horizontal mattress fashion. A second running layer of sutures applied between the mattress sutures after they have been tied. When there is not enough rim anteriorly, Tensionless suturing of the free edge of the unattached diaphragm to the costal margin with heavy, braided mattress sutures. Non-absorbable mesh or a polytetrafluoroethylene (PTFE) can be used in setting of big defects to avoid tension. When the pleura has been entered, air can be sucked out using a catheter before the last suture is placed or by inserting an intercostal tube connected to water seal drainage. Thoracotomy approach used for highly fixed herniated structures in chest cavity or if defect incidentally found during thoracic procedures.
Diaphragmatic Hernia of Bochdalek:
The 19th century Czech anatomist Vincent Bochdalek described a congenital posterolateral defect in the diaphragm. The most common defect occurs due to failure of the pleuroperitoneal canal to close at the eighth week of gestation allowing herniation of the foregut into the chest as it returns to the abdominal cavity. As a result, failure of the lung bud to mature on the ipsilateral side as well as on contralateral side due to mediastinal shift. The subsequent lung hypoplasia responsible for morbidity and mortality associated with this defect, ranges from mild to a level of severity that is incompatible with life. it is more common on the left, as that side closes last. but can also be right sided or bilateral. Tends to present early with respiratory distress soon after birth. Despite the early diagnosis by prenatal ultrasound, advanced intensive care, modern oscillatory and jet ventilation modality and extracorporeal membrane oxygenation available nowadays, the operative mortality near 20% at best specialized centers. Other anomalies of the cardiovascular system, urogenital, pulmonary, and brain or spinal cord defects should be investigated.
Perioperative management is required before definitive surgical repair. A nasogastric aspiration of air to prevent further pulmonary compromise. Blood gasses optimization, fluid balance management, correction of nutritional status and mechanical ventilation introduced if necessary to obtain required tidal volume with minimal positive end expiratory pressure (PEEP). Infants who do not respond well to maximum treatment may be placed on extracorporeal membrane oxygenation (ECMO). The final word on the timing of operation has not been established, but it is clear that emergency surgical repair is not necessary.
The repair begins with a subcostal transverse abdominal incision, leaving 2 cm to 3 cm below the costal margin. The viscera should be gently reduced. A hernia sac, present in a minority of cases, should be sought out and resected. Care should be taken to identify defect edges and assess feasibility of direct repair versus patch closure. A chest tube can be placed at this time. In direct repair the edges are approximated with non-absorbable interrupted sutures placed in horizontal mattress fashion. A large defect, however, will need to be closed with a prosthetic patch. biosynthetic porcine submucosal matrix (Surgisis), acellular dermal matrix (Alloderm), Marlex, polytetrafluoroethylene (PTFE) or Gore-tex, and abdominal wall muscle flap can be used, the patch cut larger than the defect and sutured in place with non-absorbable interrupted sutures tied over pledgets. If no posterior rim is found, the sutures can be placed around the rib or deep into the intercostal muscles.
After the diaphragm is repaired, the bowel needs to be returned to the abdomen. It may be necessary to create a ventral hernia by just closing the skin, construct a silo or use a mesh to accommodate the viscera without tension. The hernia or pouch can be closed within days. Further efforts needed in the postoperative period to achieve the best possible outcomes for these patients. Attempts have been made to correct the defect in utero, or by temporary tracheal occlusion specially in the setting of liver herniation to gradually enlarge the hypoplastic fetal lung. The final answer for this intriguing problem remains a surgical puzzle.
Acquired Defects
Hiatal Hernia:
A hiatal hernia is the result of cephalad migration of the stomach or other abdominal contents into the thoracic cavity. The hernia defect results from attenuation of the phrenoesophageal ligament over time, with the greatest incidence in older age groups, however pediatric HHs can occur with unknown true incidence and may be associated with genetic syndromes such as Marfan syndrome. There are four subtypes: Type I - Sliding Hernia: The cardia of the stomach migrates into the posterior mediastinum due to loss of posterior fixation to the preaortic fascia and median arcuate ligament. This allows for the migration of the gastroesophageal junction (GEJ) into the chest without a true hernia sac. This is the most common type with an incidence seven times that of other paraesophageal hernias. Sliding hernias are more common in women and in the 5th and 6th decades of life. Obesity and raised intra-abdominal pressure are contributory factors, but loss of diaphragmatic muscular tone may also occur. They are often found incidentally on imaging or endoscopy. Diagnosis can be difficult on imaging, as sliding hernias may spontaneously reduce. Endoscopically, the classic finding is cephalad extension of the gastric rugal folds beyond the impression caused by the crura of the diaphragm when viewed in retroflexion with full gastric insufflation. The GEJ is intrathoracic so reflux can occur with other consequences. The presence of an asymptomatic sliding hernia does not mandate repair.
Type II - Rolling or Paraesophageal Hernia:
A defect in the esophageal hiatus anterolateral to the esophagus caused by weakness of the phrenoesophageal membrane permitting herniation of the gastric fundus and antrum along-side the esophagus into the chest. The GEJ remains in an intra-abdominal position below the esophageal hiatus and reflux does not occur. Paraesophageal hernias (Type II-IV) have a true hernia sac. Incidence of type II is two to four times greater in women, with the median age of presentation during the 7th decade of life. Diagnosis can be made by plain radiography (air-fluid level seen in mediastinum), endoscopy, or barium swallow - which has near 100% sensitivity. On endoscopic retroflexion, one should note the shaft of the scope coming through an orifice (GEJ) separate but adjacent to the paraesophageal hernia into which rugal folds ascend past the crural indentations. Symptomatic type II hernias are a clear-cut indication for repair. However, due to the potential life-threatening complications and increased morbidity and mortality associated with emergent repair, most surgeons recommend repair electively soon after diagnosis, regardless of symptoms.
Type III - Combined sliding-rolling or mixed hernia:
An upward dislocation of both the cardia and fundus occurs when there is an anterior defect in the hiatus with a concomitant loss of fixation of the cardia. The GEJ is intrathoracic. Endoscopic evaluation reveals the gastric pouch above the level of the diaphragm with the GEJ entering approximately halfway up the pouch. Some surgeons believe that true type II paraesophageal hernias are rare and that most are type III hernias with the sliding component in the reduced position. Indications for repair are the same as type II hernias.
Type IV:
Type IV hernias are similar to type III; however additional organs migrate into the chest along with the stomach. Colon, omentum, and spleen are the organs most commonly involved. These hernias are typically large and surgical repair is indicated.
Giant Paraesophageal Hernias and Volvulus:
The stomach is tethered in the intra-abdominal position by a number of anchors, including the gastrohepatic, gastrosplenic, gastrocolic, and phrenoesophageal ligaments. Laxity in these structures can lead to volvulus of the stomach.
Organoaxial volvulus is the most common type and refers to rotation of the stomach around the longitudinal axis (GEJ to pylorus). Because the duodenum and gastrohepatic ligaments are relatively fixed, the greater curve rotates along this axis, typically anteriorly. A complete organoaxial volvulus results in closed-loop obstruction and is considered a surgical emergency.
Mesoenteroaxial volvulus refers to rotation along the transverse axis (bifurcation of the lesser and greater curves), with the antrum rotating anteriorly and superiorly. This type of volvulus is less common and typically results in transient, recurrent symptoms of partial obstruction. Laxity of the gastrosplenic ligament is thought to result in mesoenteroaxial volvulus. This type of volvulus is not typically associated with paraesophageal hernias.
The term giant paraesophageal hernia typically refers to type II-IV hernias with greater than 33% of the stomach in the intra thoracic position. Large paraesophageal hernias are predisposed to organoaxial rotation. A complete intrathoracic stomach (the entire stomach migrated into the chest) typically requires some degree of volvulus to occur. Giant paraesophageal hernias commonly result in presbyesophagus, as the esophagus becomes fibrotic and shortened from unabated reflux.
Symptoms & Complications
Type I hernias are often asymptomatic or present with minor symptoms of reflux or regurgitation due to a mechanically defective LES. The negative intrathoracic pressure decreases the LES pressure, the hiatus becomes widened, and the geometry of the angle of His is altered. These changes result in failure of the anti-reflux "valve" created by the LES.
Paraesophgeal hernias (type II-IV) are more likely to have symptoms of dysphagia, postprandial fullness/early satiety, abdominal pain, and chest pressure. Reflux symptoms are also common in paraesophageal hernias, with the exception of true type II hernias where the GEJ and LES remain intact. Patients may present with anemia and melena from recurrent bleeding ulcerations created in the gastric mucosa (Cameron ulcers). Paraesophageal hernias commonly become incarcerated as the intra-abdominal contents gradually migrate into the chest and subsequently are unable to reduce due to the narrower hiatus. As these hernias enlarge, dyspnea may result as the fixed space of the thoracic cavity is filled with intra-abdominal contents. Strangulation, with associated bleeding, necrosis, and perforation can occur from a complete volvulus with closed-loop obstruction.
Complete obstruction from an organoaxial volvulus is suggested by Borchardt's triad: chest pain, retching with an inability to vomit, and inability to pass a nasogastric tube. As stated previously, this is a surgical emergency.
Principles of Repair
The primary goal of hiatal hernia repair is reduction of the herniated structures to their normal anatomic, intra-abdominal position. A number of key steps are needed to accomplish this. First, the hernia contents must be reduced and the hernia sac completely everted. It is important to enter the correct plane, with dissection being carried out in the avascular, areolar plane outside the hernia sac within the mediastinum. Controversy exists as to whether the sac needs to be excised. Additional mediastinal dissection is needed to mobilize the esophagus to ensure the GEJ is below the diaphragm and at least 2.5 cm of esophagus is located intra-abdominally.
Intrathoracic mobilization should extend from the pericardium anteriorly to the preaortic plane posteriorly, from right to left pleura laterally, and proximally to the inferior pulmonary veins. In cases where the esophagus is shortened despite extensive mobilization, a Collis gastroplasty may be needed. The vagus nerves should be identified and preserved during this dissection. Most recommend an anti-reflux procedure next, as the LES is typically compromised. In addition to providing a barrier to reflux, a fundoplication can serve as a mechanical anchor to maintain thesto1nach within the abdo1nen. Details of fundoplication options are covered in the subsequent chapter. In patients who cannot tolerate a long procedure, are unstable, have a complicated paraesophageal hernia, or have a shortened esophagus, gastropexy may be performed instead of a wrap. In this case, the fundus is sutured to the diaphragm and abdominal wall along the line of the short gastrics to maintain the stomach in proper position. However, reflux can occur with this option and patients should be maintained on proton-pump inhibitors.
The crura are then reapproximated using heavy braided interrupted sutures. Maintaining the integrity of the peritoneal lining of the crus during dissection is vital to assure these sutures do not pull through the soft underlying cn1s muscle. Sutures are placed posteriorly, which pushes the esophagus anteriorly and because of the angle of the crus, provides more intra-abdominal esophageal length. It may be necessary to place additional sutures anteriorly for large hiatuses. Too tight of a crural closure may lead to dysphagia, and too loose a reapproximation may lead to later herniation of the wrap. Experience is helpful in determining how many crural stitches are needed, but a good estimate is made by passage of a finger into the hiatus in open cases or a slightly opened grasper in laparoscopic cases.
Also controversial is the use of mesh, which has been advocated as an adjunct to reinforce the crural repair, especially with very large defects where the crura cannot be approximated in a tension-free fashion. Though some prospective data demonstrate lower recurrence rates using mesh, most surgeons prefer to avoid the use of prosthetic materials due to the risk of erosion into the GI tract. High mediastinal dissection, inducing a left pneumothorax to create a "floppy" diaphragm, mobilizing the splenophrenic attachments, and lateral diaphragmatic relaxing incisions are used to obtain adequate hiatal approximation without tension, and if done properly, should make the need for mesh a rare occurrence.
Surgical Approach:
Currently, most hiatal hernias are approached laparoscopically. However, controversy exists as to whether a laparoscopic or open approach is best, particularly with large hernias. In addition to the more commonly noted benefits of a minimally-invasive approach, laparoscopy provides excellent visualization of the mediastinum and allows extensive mobilization of the esophagus under direct vision. Advocates for an open approach argue that the insufflation needed for laparoscopy puts excessive tension on the diaphragm, thereby complicating re approximation of the crura. However, as stated previously, this can be overcome with a number of maneuvers. A transthoracic approach has historically been the preferred approach for larger or recurrent hernias with suspected esophageal shortening, as reduction of the large hernia and gastroplasty for esophageal lengthening can easily be performed through the left chest (Collis Belsey approach). However, a gastroplasty can also be performed easily via a transabdominal approach, making the pain associated with thoracotomy a less attractive option if the hernia can be reduced via the abdomen.
Results: Surgical repair of paraesophageal hernias achieves symptomatic relief, including resolution of anemia, in 90% of patients at 4 years. Small to moderate radiographic recurrences and reoperation for symptomatic recurrences have been reported in 16% and <5% of cases, respectively, in recently reported series.
References:
1. Kaiser L. Mastery of Cardiothoracic Surgery, third edition 2014.
2. Shields’ General Thoracic Surgery, eighth edition
3. Grivell RM, Andersen C, Dodd JM. Prenatal interventions for congenital diaphragmatic hernia for improving outcomes. Cochrane Database Syst Rev. 2015 Nov 27;2015(11):CD008925. doi: 10.1002/14651858.CD008925.pub2. PMID: 26611822; PMCID: PMC8947621.