by Dr. John Fondacaro, Diplomate ACVIM & Dr. Sean Hillock, Diplomate ACVIM
Interventional Radiology Techniques (Offered at the Veterinary Medical Center of Long Island Internal Medicine Department)
Bronchoscopic intraluminal stents for tracheal collapse and other occlusive tracheal diseases.
Urethral stents for obstructive urethral diseases.
Transurethral submucosal collagen implantation.
Since there is not an abundance of information about these procedures in the literature, the following general information will help you decide which patients may be possible candidates and allow you to adequately prepare owners prior to referral.
Bronchoscopic intraluminal tracheal stents:
Self-expanding metallic tracheal stents are an effective alternative to surgical placement of extraluminal support rings. They are mainly indicated for patients with severe intra or extrathoracic dynamic tracheal collapse that continue to cough and remain uncomfortable despite aggressive medical management for their conditions. Other potential indications include tracheal stenosis, neoplasia, and strictures. The stents are placed with bronchoscopic guidance after full assessment of the lower and upper airways and careful measurement of the affected segement(s).
Medical management with weight control, corticosteroids, antitussives, bronchodilators, +/- antibiotics, and sedatives should be tried before the patient is referred for stent placement. Not all patients with tracheal collapse are candidates for this procedure. Pre-placement bronchoscopy to fully evaluate the lower airways for bronchomalacia and lower airway collapse will be required. If found to be a candidate, thoracic radiographs with positive end-expiratory pressure and negative pressure applied to the airways will be performed to size the stent for the individual patient.
Owners should be made aware that this is a salvage procedure, continued medical management will be required lifelong, and that complications are more likely to occur over time (especially if coughing is not controlled with medical management). Follow-up bronchoscopy will be strongly recommended, if not required, within the first three months after placement (or sooner if the patient is having difficulties) to check for complications such as granuloma formation, migration, infection, fracture, and adjacent segment collapse.
Urethral stenting is a novel treatment modality for obstructive diseases of the urethra, mainly urethral and prostatic neoplasia. This palliative procedure can allow normal urine flow despite some very aggressive obstructive urethral disease. This procedure will allow time for chemotherapeutic intervention (chemo, NSAIDS) to affect the tumor or to allow time until natural disease progression occurs, if the owners do not elect chemotherapeutic intervention. As with the tracheal stents, careful measurement of the urethra is required. This is done with the use of positive contrast to accurately measure normal urethral diameter and the affected length of the urethra prior to stent placement.
Owners should be made aware of the potential for urinary incontinence (approximately 25-35% of the time), urinary tract infection, re-stricture due to re-growth of tumor at the opposing ends of the stent, and stent migration.
Urethral collagen implantation:
This procedure is a novel treatment for urethral sphincter mechanism incontinence that is non or no longer responsive to medical management with estrogen, PPA, and/or imipramine, etc. This procedure can be performed on an outpatient basis. Bovine collagen is injected at the urethral orifice and acts as an anatomic sphincter to prevent urine leakage. There are few complications associated with this procedure, but mainly include continued urinary incontinence or relapse of incontinence over time. Most patients that relapse will require a repeat injection or concomitant therapy with PPA and/or estrogen.
I am very excited to offer these novel therapeutic interventions to our referring veterinarians and their patients. Over time, I hope to expand the scope of what we can do with similar techniques. Please do not hesitate to contact either Dr. Fondacaro or Dr. Hillock at the VMCLI if you have any questions regarding these new procedures.