Hiatal Hernia and GERD

Esophagus Anatomy

• The esophagus is a muscular tube connecting the mouth to the stomach.
• It's about 25 cm long.
• At rest, the esophagus is collapsed.
• The upper two-thirds are flat, and the lower third is rounded.
• It starts at the lower edge of the cricoid cartilage (C6).
• It travels down the front of the spine through the posterior mediastinum, passes through the diaphragm, and enters the abdomen.
• It terminates at the cardiac orifice of the stomach, opposite the eleventh dorsal vertebra.
• The average adult esophagus is 18-26 cm long.
• In endoscopic view, the esophagus is 38-40 cm long, measured from the incisor teeth.
• It's conventionally divided into three parts: upper, middle, and lower.
• Unusual arterial supply derived from vessels feeding mainly other organs such as the thyroid, trachea, and stomach.

Venous Drainage

• The upper third of the esophagus drains into the inferior thyroid veins.
• The middle third drains into the azygos veins.
• The lower third drains into the left gastric vein, a tributary of the portal vein.
• Esophageal varices are a complication.

Lymph Drainage

• The upper third of the esophagus drains into the deep cervical nodes.
• The middle third drains into the superior and inferior mediastinal nodes.
• The lower third drains into the celiac lymph nodes in the abdomen.

Nerve Supply

• The sympathetic supply is mediated by intermediate lateral T1-T10 spine. It regulates blood vessel tone, esophageal sphincter tone, and glandular function.
• The parasympathetic supply is mediated by the ambiguous nucleus and the dorsal motor nucleus of the vagus nerves. It provides motor and secretory innervation to the muscles and glands.
• Inferior to the lungs, the vagus nerves join the sympathetic nerves to form the esophageal plexus. The left vagus lies anterior to the esophagus, while the right vagus lies posterior to it.
• The parasympathetic vagus nerve is motor to the muscular layers and secretomotor to glands.
• The sympathetic nerve fibers originates from the thoracic chain and are responsible for contracting the sphincters (tone), relaxation of the wall, and glands, activity, and blood flow.
• Intramural plexus combine all innervation in plexuses and ganglia in muscular layers (myenteric or Auerbach's plexus) and submucosa (Meissner plexus).
• The afferent fibers of the vagus do not play a direct role in visceral pain transmission, rather spinal afferent fibers act as nociceptors. Esophageal pain resembles cardiac pain, with sensitive afferent fibers converging from the heart and the esophageal neurons in the dorsal horn of the thoracic and cervical spine.

Esophageal Functional Anatomy

• Esophagus functions to transport the bolus from the pharynx to the stomach. This also prevents gastroesophageal reflux and allows belching and vomiting.
• The esophagus comprises striated muscle in the upper one-third (cervical esophagus), smooth in the middle two-thirds (thoracic esophagus), and a transition zone of 4-6cm.
• Functional areas:
  1. Upper esophageal sphincter (UES) and pharyngo-esophageal junction
  2. Esophageal body
  3. Lower esophageal sphincter (LES) and esophagogastric junction (EGJ) and crural diaphragm

Esophagus Divided into Sphincters

• Upper Esophageal Sphincter (UES): A 2-4 mm zone of high pressure between the pharynx and esophagus. It corresponds to the cricopharyngeal muscle.
• Lower Esophageal Sphincter (LES): Located at the junction of the esophagus and stomach, often at or just below the diaphragmatic hiatus. Physiological function is notable, but anatomical distinction isn't straightforward.

Esophagus: Anatomy

• The esophagus is the narrowest region of the alimentary tract, except the vermiform appendix.
• It has three indentations during its course.
  • At 15-16 cm from the incisor teeth: cricopharyngeal sphincter (normally closed).
  • At 25-27 cm: aortic arch and left main bronchus.
  • At 40 cm: where it pierces the diaphragm, a physiological sphincter (LES) is situated.

Areas of Esophageal Foreign Body Entrapment

• Most common site of esophageal impaction: thoracic inlet (between clavicles on chest radiographs) due to anatomical transition from skeletal to smooth muscle and cricopharyngeus sling at C6.
• About 70% of blunt foreign bodies lodged in the esophagus reside here.
• Another 15% lodge in the mid-esophagus where the aortic arch and carina overlap.
• Remaining 15% are lodged at the LES at the gastroesophageal junction.

Esophageal Wall Structure

• The esophageal wall has four layers from within outwards: mucosa, submucosa, muscular coat (muscolaris propria), and outer most fibrous layer (adventitia).
• Unlike other gut areas, it lacks a distinct serosal covering but has a thin layer of loose connective tissue.

Esophageal Histology

• The esophageal mucosa is composed of stratified non-keratinized squamous epithelium.
• Layers include squamous epithelium, lamina propria, muscularis mucosae, mucous acini of esophageal glands proper, submucosa, muscularis externa with inner circular and outer longitudinal muscle layers, and adventitia.
• Nerve fibers are also present.

Esophagus-Gastric Junction

• Coronal section anatomy describes the esophagus and gastric junction.
  • Esophageal Mucosa: The inner lining of the esophagus.
  • Submucosa: Connective tissue beneath the mucosa.
  • Phrenoesophageal ligament: Connects the esophagus to the diaphragm.
  • Diaphragm: The muscular partition separating the chest and abdomen.
  • Supradiaphragmatic fascia: The fascia above the diaphragm.
  • Infradiaphragmatic (transversalis) fascia: The fascia below the diaphragm.
  • Cardiac notch: The indentation on the stomach where the esophagus connects.
  • Gastric folds (rugae): The folds in the stomach lining.
  • Phrenoesophageal ligament (descending limb): The portion of the ligament below the diaphragm.

###Esophageal Peristalsis

• Esophageal peristalsis is initiated by deglutition ("primary" peristalsis) or local distension ("secondary" peristalsis).
• Deglutition is a complex reflex, involving voluntary chewing, saliva mixing, bolus formation, and involuntary head and neck muscle contractions.
• The pharyngeal constrictor muscles push the bolus into the esophagus.
• Primary peristalsis, involving sequential circular muscle contraction in the esophageal body, propels the bolus.
• Relaxation and opening of the LES follows, enabling bolus entry to the stomach.
• Secondary peristalsis occurs in response to esophageal body distension (e.g., refluxed gastric contents).

Gastroesophageal Reflux Disease (GERD)

• GERD is a condition where stomach contents reflux into the esophagus causing symptoms and/or complications.
• Montreal definition includes esophageal (symptomatic typical reflux syndrome, Syndromes with Esophageal injury, reflux stricture, reflux laryngitis,) and extra-esophageal (Reflux cough, reflux asthma, Refux laryngitis, Refux dental erosions, atypical symptoms) syndromes.

Epidemiology of GERD

• GERD prevalence is significant in industrialized countries, affecting approximately 20% of the total population.
• Prevalence increases with age, and older patients tend to have less symptomatic but more severe GERD.
• More frequent in Western Europe and North America, less prevalent in Asia-Pacific regions.
• Prevalence trends show an increase from 1970 to 1995 for peptic ulcer disease and GERD.
• Incidence of GERD and esophageal adenocarcinoma rose significantly over this period.

Progression of GERD

• GERD can progress, with normal LES to GERD, Esophagitis, Erosive Esophagitis, Peptic stricture developing. Increased risk of Barrett's Esophagus (BE) (40 times relative to normal), with esophagus adenocarcinoma having the highest risk.

GERD Characteristics

• Pathogenesis is an imbalance between esophageal protective mechanisms(Competence of LES, Esophageal peristalsis, Acid clearance, Mucosal resistance, Saliva buffering) and aggressive factors (Refluxate characteristics: volume, HCL, pepsin, bile, pancreatic enzymes).
• GERD results from impaired anti-reflux barrier function at the gastroesophageal junction, not necessarily from increased acid secretions.

GERD Pathophysiology

• Esophageal protective mechanisms (lower esophageal sphincter resting tone, esophageal peristalsis, mucosal resistance, and salivary buffering) must balance aggressive factors (pH, pepsin, bile, pancreatic enzymes in refluxate).
• Incompetent antireflux mechanisms allow refluxed (gastric) contents to move into and beyond the esophagus.
• This can cause mucosal damage and symptoms.

GERD Pathophysiology: Lower Esophageal Sphincter (LES)

• LES is a 2-4cm portion of a “functionally thickened” smooth muscle at the gastroesophageal junction.
• The LES has a high-pressure resting tone (usually ~20 mmHg, but range is 10-40 mmHg).
• Swallow-associated LES relaxation and transient LES relaxation occur.

Esophagogastric Junction

• LES muscles, although not unusually thicker than esophageal muscles in autopsy specimens, are dynamic in thickness and tone changes, correlating with LES pressure changes.
• The changes due to dynamic LES tone don't show up as clear anatomical distinction in autopsy.

Angle of His

• The intrinsic LES in humans is composed of at least two muscles: circular and gastric sling muscles.
• The gastric sling runs along the left lateral aspect of the sphincter, completing this portion.
• The presence and location of gastric sling muscle may be important to maintain an acute angle of His at the greater curvature of the gastroesophageal junction and potentially facilitate a flap valve function as an anti-reflux mechanism.

High-Resolution Manometry (HRM)

• HRM is a new gastrointestinal motility diagnostic system that measures intraluminal pressure activity using closely spaced pressure sensors.
• HRM is used for measuring multiple pressures simultaneously along the entire esophagus.
• A commercially available high-resolution catheter has 36 solid-state circumferential sensors spaced at 1cm intervals along the entire intracorporal portion of the catheter assembly, allowing for pressure assessment without the need for catheter pull-through maneuvers.
• HRM is more precise than prior methods, reducing procedure time by approximately 50%.

Hiatal Hernia

• A hiatal hernia is a dislocation of the proximal stomach into the chest through the diaphragmatic hiatus, separating the lower esophageal sphincter from the crural diaphragm.
• A sliding hiatal hernia, a more pathogenic mechanism in GERD, may reduce GE junction competence and cause acid to accumulate near the diaphragm, which is lower pressure than the abdomen).
• Hiatal hernia is not synonymous with GERD; GERD requires a dysfunctional LES.

GERD Risk Factors

• Hiatal hernias, high body mass index (BMI), diet factors (e.g., coffee, chocolate, alcohol, fatty foods, citrus fruits, and peppermint), smoking, and certain medications.

GERD Medications to Avoid

• Certain medications, such as beta-adrenergic agonists, theophylline, anticholinergics, progesterone, tricyclic antidepressants, alpha-adrenergic antagonists, diazepam, and calcium channel blockers, can impair LES function.
• Some medications cause damage to the esophageal mucosa such as acetylsalicylic acid and other NSAIDs, tetracycline, quinidine, and bisphosphates.

Causes of GERD

• Idiopathic (over 80% of cases).
• Secondary causes include: obesity, scleroderma, systemic lupus erythematosus, pregnancy (increased estrogen and progesterone lead to increased intra-abdominal pressure).

GERD Diagnosis

• Identify symptoms associated with gastroesophageal reflux (typical include heartburn and acid regurgitation; atypical include dysphagia, non-cardiac chest pain resembling myocardial infarction, odynophagia).
• Identify esophageal inflammation (via endoscopy).
• Various diagnostic modalities are available, including the effectiveness of proton pump inhibitors (PPI) therapy, esophageal-gastro-duodenoscopy (EGD), pH impedance monitoring, and high-resolution esophageal manometry.

GERD Symptoms

• Typical esophageal symptoms include heartburn, acid regurgitation.
• Atypical symptoms include dysphagia, non-cardiac chest pain, odynophagia.
• Extra-esophageal symptoms include sore throat, hoarseness, dysphonia, chronic posterior laryngitis, chronic cough, wheezing, and asthma.

Clinical Spectrum of GERD

• Non-erosive reflux disease (NERD) accounts for over 50% of GERD cases characterized by symptoms without significant macroscopic mucosal lesions.
• Erosive esophagitis and chronic complications are features of more severe GERD cases.
• The clinical spectrum of GERD ranges from mild (NERD) to severe (erosive esophagitis, stenosis, Barrett’s esophagus, and adenocarcinoma).

GERD Complications

• GERD complications include peptic stricture, Barrett's esophagus, ulceration, and bleeding.

Barrett’s Esophagus

• A change in esophageal epithelium, characterized by the replacement of normal stratified squamous epithelium with simple columnar epithelium (intestinal metaplasia) just above the gastroesophageal junction (GEJ).
• It can be identified endoscopically and confirmed with biopsy.
• Subtypes of BE include non-dysplastic, low-grade dysplasia, and high-grade dysplasia.

Barrett's Esophagus: Criteria

• The Prague C&M Criteria for evaluating Barrett's esophagus. Includes maximal length (M) and circumferential extent (C) of the metaplastic area of the esophagus, identification of the gastroesophageal junction, and detection of hiatal hernias.

Barrett's Esophagus: Biopsy Protocol

• A minimum of 8 biopsies are needed for proper assessment of intestinal metaplasia (IM) status.
• Biopsies should be taken distally (starting 1-2 cm above the GEJ) and at 2 cm intervals during proximal advancement.
• Targeted biopsies of visible lesions should be performed before random ones in order to avoid missing regions of columnar epithelium. Ideally, the examination should occur after the resolution of erosive esophagitis.

Barrett's Esophagus Screening

• Screening for Barrett's esophagus (BE) in the general population isn't routinely recommended.
• Screening should be considered in individuals with chronic GERD (≥13 years) and at least 3 of the following risk factors: age ≥50, white race, male sex, obesity, and history of hiatal hernia

Barrett's Esophagus Surveillance

• Endoscopic surveillance with biopsy for histologic assessment of disease progression is the only current method for surveillance and follow-up of BE patients.
• Intervals depend on the degree of dysplasia, with more frequent procedures for high-grade dysplasia.
• Patients with BE should receive PPI therapy once or twice daily.

Barrett's Esophagus Treatment

• Treatment options include chemoprevention (PPIs, aspirin, NSAIDs, statins, anti-HER2/neu), ablation (multipolar electrocoagulation, laser therapy, argon plasma coagulation), photodynamic therapy, cryotherapy, radiofrequency wave ablation. and surgery (esophagectomy, endoscopic mucosal resection).

Esophagitis

• Also known as inflammation of the esophagus. Can lead to other complications.

Adenocarcinoma

• One of the severe complications of GERD. The cells have changed and exhibit abnormal growth patterns.

pH monitoring

• Most accurate for reflux episodes in time, frequency, and duration.
• Reflux is determined by pH drops below 4.0 in catheter-based or wireless pH monitoring.

24-hour Esophageal pH Monitoring

• This test documents correlation of reflux episodes and symptoms.
• The percentage of time with pH <4.0 (acid exposure time, AET) is used to distinguish physiological versus pathological reflux.
• It's indicated for symptomatic patients on acid-suppressive therapies, individuals with atypical symptoms and negative endoscopy findings, and pre/post-surgical evaluations.

Impedance pH Monitoring

• The combination of pH with impedance monitoring provides comprehensive assessment of reflux episodes based on physical and chemical properties of the refluxate (liquid, gas, mixed).
• Measures the impedance to alternating current and the pH of the esophageal lumen contents.

High Resolution Esophageal Manometry

• A method that measures multiple pressures simultaneously along the entire esophagus using intraluminal pressure sensors.

Esophageal Manometry Components

• HRM catheter with 36 solid-state circumferentially oriented pressure-sensing elements in spaced 1cm intervals.
• These components include sensors along the entire intracorporal portion for pressure assessment and display components.
• Analysis software is needed for interpretation and storage of data.

Therapeutic Gain

• Statistical analysis of treatment efficacy based on randomized controlled trials.
• Therapeutic gain estimates for various conditions (e.g., esophagitis healing, heartburn/regurgitation relief, chest pain/chronic cough relief, hoarseness/asthma improvement)

Explore the intricate relationship between hiatal hernias and gastroesophageal reflux disease (GERD) in this quiz. Discover how anatomical changes can impact the severity of GERD and understand the physiological mechanisms involved. Test your knowledge on the prevalence of GERD and its connection to other esophageal conditions.