Dr. Kramer On: Bronchial Stenting
(Continued from cover page)
...significant collapse -- anywhere from 75%-100% collapse -- of either their left mainstem bronchus or their left caudal lobar bronchus (LB2) or left cranial lobar bronchus (LB1). It seemed that the left caudal lobar bronchus was the one that was most severely affected followed by the left cranial lobar bronchus and, also, to a significant degree, the left mainstem bronchus. There was some partial collapse in some of the dogs of some of the right-sided airways but not to the same degree as on the left side.
The other thing that was very evident was that you could see dynamic compression of the collapse with each beat of the heart during the cardiac cycle. So you could see the bronchi just getting snapped shut each time the heart beat. And that caused a significant amount of irritation and inflammation of that area of the airway. When I looked distal to that area of collapse to assess how the distal airways looked, those airways were essentially normal so there was no distal collapse past that focal area of compression.
The purpose of this study was to see whether we could develop a new therapeutic strategy for dealing with this clinical syndrome, specifically placing a stent in the collapsed bronchus to keep it open thereby relieving or decreasing the cough. But if we found that there was diffuse airway disease or if there was distal airway disease, the stent wouldn't be that appropriate because it probably would not result in improvement of the cough.
Since we found that, distal to the area of collapse, the airways all looked pretty normal, we decided that a stent would be a possible therapeutic option and we've gone ahead as the second part of the study to start placing Nitinol stents in the bronchus to open them up. We've placed them in the most severely collapsed dogs -- that have 100% collapse of their left caudal lobar bronchus -- and it has resulted in significant improvement.
I presented this information at the most recent American College of Veterinary Internal Medicine conference down in San Antonio in June. Click here to see the abstract.
It's still a very preliminary study and we need to look at more dogs with this condition. We've been underwriting the cost of the study through some private money that we've had available to offset the cost to the owners for the workup and the procedures. It's not 100% free but the cost is significantly reduced. We're still looking for more cases that might be appropriate to assess and even possibly stent. The process is similar to what we do for stenting collapsing tracheas which we've been doing for a few years now but it's a little more difficult and the stents are much smaller.
If any of the veterinarians reading this have cases for which they think this procedure might be helpful, they should contact me or have their client contact us to come in and see me for an initial evaluation.