Esophageal Balloon Dilation and Esophageal Stenting
Esophageal strictures are frustrating to treat for both veterinarians and physicians. Patients classically present with signs of regurgitation. Strictures in the esophagus can be secondary to reflex esophagitis (commonly post-anesthesia), caustic substance ingestion, medications sitting on the esophageal mucosa for lengths of time (i.e. doxycycline tablets in cats), from esophageal foreign bodies, etc. Many alternative therapies have been tried because recurrence is very common. Balloon dilation or bougienage procedures using endoscopic guidance is currently the treatment of choice in veterinary medicine.
Regardless of the intervention chosen, many of these strictures recur and present as a monetary and clinical dilemma for our feline and canine patients. In human medicine fluoroscopy, in conjunction with endoscopy, is used for dilation of esophageal strictures, allowing better visualization that the waist of the stricture is not just stretched, but completely broken. With a similar theory to the NPS cases, esophageal strictures would ideally be balloon dilated with a stent left in place to keep the stenotic lesion open for the time it would take the tissue to re-stenose. The biggest concern about doing this in the esophagus is that this area is very motile (vs the nasopharynx) and food will need to pass through the area.
The risk of the stent migrating into the stomach, or proliferative tissue growth around the ends of the stent material, makes permanent stenting for benign disease less than ideal. In order to circumvent these concerns pliable stents with a shape that would ideally hold up again peristalsis (dumb-bell and self expanding) have been tried. Knowing that the stenotic tissue will heal over 14 or more days, having a stent that can be removed or resorbed (polylactic acid or PDS stents) in a few months is being investigated. This has been studied in humans for some time and we too have now been intently investigating this option.
Using both fluoroscopic and endoscopic guidance, the stent is centered over the esophageal stenosis inside its delivery system. Once deployed the stent is expanded in place and tacked with a suture (either endoscopically or manually placed suture) to prevent stent migration into the stomach. The prelimary results thus far have been promising. In the future this may be a consideration at the time of 2nd or 3rd balloon dilation to avoid serial anesthetic procedures and high costs.
Esophageal-jejunal Feeding Tubes
Enteral methods of feeding are preferred over parenteral nutrition in humans due to the benefits on gut mucosal integrity, barrier function, and lower complication rates. Jejunal feeding in small animal patients is controversial. In animals that are intolerant of gastric feedings, have intractable vomiting, have pancreatitis where pancreatic exocrine duct by-pass is desired, or are unconscious and regurgitation or reflux is a concern (ventiled animals), feeding directly into the jejunum is recommended.
Classically this has been done via surgical or laparoscopic technique with a high complication and orad dislodement rates. Due to the ease of placing a nasal feeding tube or an esophagostomy feeding tube, tubes have been able to be placed into the jejunum from the nares (NJ) or esophagus (EJ) with fluoroscopy +/- endoscopy, eliminating the complications associated with septic peritonitis or unnecessary gastric or jejunal orificies. NJ and EJ tube placement is aided with fluoroscopy visualizing the guidewire and catether placement into the duodenum and into the jejunum. If an upper GI endoscopic procedure is being performed at the same time (see pictures in presentation) than wire placement across the pylorus can be done through the endoscope. This technique is fast, effective and fairly inexpensive when compared to surgical placement and parenteral access and intensive care monitoring of TPN.
Colonic Stenting
Colonic obstructions are rare in small animal patients. They can be due to neoplastic lesions, strictures, or granulomatous lesions. In humans, colonic stents have been available for over a decade and are most commonly placed for people with neoplasia who are a prohibitive surgical risk or resection holds little chance of surgical cure. They have been used as a mechanism to help deobstipate for bowel preparation prior to resection and anastomosis.
In humans, colonic stents can either be placed through the endoscope for direct visualization while they are deployed, or they can be placed over a guidewire under fluoroscopy alone. They are preferred to be placed through the scope for precise stricture localization, for proximal tumor locations and to guide the stent across acute angulations in the colon. In humans clinical success is seen in up to 95% of patients. At the University of Pennsylvania we have placed 4 colonic stents in cats to date; 3 for tumors and 1 for a stricture. In all cases colonoscopy was done to visualize the lesion and help localize the lesion fluoroscopically. A guidewire was then advanced through the stenotic lesion. Under fluoroscopic guidance a self-expanding metallic stent (SEMS) was placed across the stenotic lesion or tumor and the stent was deployed.
Patency was re-established immediately in all cases and subsequent deobstipation was achieved. All cats were fecally continent, and no stent migrations were seen. The stent was visualized to be encorporated into the colonic mucosa within 4 days in one cat that was re-scoped