Interventional Radiology (IR) involves the use of an imaging technology called fluoroscopy that allows us to “see” into the body indirectly. With this capability, we’re able to perform diagnostics and treatments by entering the body through natural orifices or blood vessels which eliminates the need for traditional surgery.
Examples of Interventional Radiology in human medicine include implantation of coronary artery stents and even treating cancer. We’ve adopted the principles of Interventional Radiology to help our veterinary patients – your pets – as well in procedures such as:
1) Treatment of Ureteral Obstructions
According to a study published in 2013 ureteral obstructions are currently the #1 cause of acute kidney failure in cats.
The ureter is the tiny (under half a millimeter in diameter!) tube that carries urine from the kidney to the bladder. Ureteral obstruction can occur when a kidney stone passing through the ureter gets stuck. This blocks the flow of urine to the bladder which leads to kidney damage and the build-up of uremic toxins in the body–big time bad news. This condition can cause critical illness within hours and requires emergency treatment.
Traditional decompressive surgical treatments for this condition had high complication rates – up to 34-60% patients had an unsuccessful outcome with surgery. With newer techniques that utilize Interventional Radiology the success rate increased to 80-95%.
2) Treatment of Severe Tracheal Collapse
Tracheal collapse is a common problem in small breed dogs that can cause the airway to narrow. This leads to frequent coughing, exercise intolerance, and cyanosis (turning blue from lack of air). Medications can provide effective relief for about 80% of patients.
But for those patients with particularly severe forms of the condition, a tracheal stent can help open the airway, allow them to breathe more normally, and improve their quality of life. Tracheal stents can be placed using Interventional Radiology techniques so patients can often go home the same day.
3) Treatment of Urethral Obstruction
The urethra is the tube that carries urine from the bladder out of the body. This tube can become blocked in patients who have tumors in the bladder or the urethra itself. This type of blockage can be extremely uncomfortable and may lead to urinary tract infections, kidney damage, and rupture of the bladder.
Urethral stenting can be performed relatively quickly and allows us to open the urethra to allow the patient to urinate. As with tracheal stenting, these patients often go home the same day.
4) Treatment of Cancer
Sometimes patients have tumors that are either too big or too close to other vital organs to be removed with surgery. Oral or injectable chemotherapy is generally not very effective for these tumors and exposes the patient to troubling side effects of chemotherapy drugs. In some cases, we can make a very small incision into a blood vessel in the inner thigh and guide a catheter through this blood vessel into the tumor.
From there a strong, targeted dose of chemotherapy can be delivered straight to the tumor, followed by an embolization compound to cut off the flow to the tumor. This technique offers a safe treatment for patients that previously had no other options.
5) Transvenous Coil Embolization for Intrahepatic Portosystemic Shunts
Portosystemic shunts are congenital abnormalities (aka birth defects) in which major blood vessels to the liver grow around the organ rather than into it. When the abnormal (shunt) vessel is located within the liver lobes, it is called an intrahepatic shunt. When the shunting vessel is located some distance away from the liver, it is called an extrahepatic shunt.
Extrahepatic shunts are easily accessed by opening the abdomen, but intrahepatic shunts are much more difficult to access because they are deep within the tissues of the liver. Surgery to fix extrahepatic shunts is very successful, but this is not the case for intrahepatic shunts. Surgery in these cases carries a complication rate of up to 77%, with overall mortality rates as high as 64%.
Using Interventional Radiology techniques, the shunt can be accessed through the jugular vein and treated without ever opening the abdomen. The complication rate for this procedure is about 2%, with good long-term success in about 75% of cases. Patients generally stay the night after the procedure and go home the next day with a small bandage on their neck!
A big thank you to Jodi Kuntz, DVM, DACVIM (SAIM) for helping us with this list…