Yet again, thin film banding of portosystemic shunts is getting a bad wrap (pun intended) for failing to attenuate portosystemic shunts in dogs. Two recent publications in Veterinary Surgery by Dr. Or et al (here and here) described the use of CT angiography to better define portoazygous shunts and the transdiaphragmatic approach required to attenuate them at their insertion within the thoracic cavity. In their study, 9 dogs had transdiaphragmatic attenuation of their portoazygous shunts using either "Marlborough cigarette" wrapping or an ameroid.
'3/5 shunts banded with Marlborough cigarette wrappers (fake cellophane i.e. plastic) remained patent, and the other 2/5 were lost to follow up. 3/5 dogs with patent shunts had revision surgery using ameroids.'
The authors contended that the dogs that had their shunts banded using cigarette packaging failed to attenuate due 'potential differences in the ability of the thoracic cavity to mount a fibrous reaction.' This reasoning is fair, but flawed for the following reasons:
- Ever seen a pyothorax, thoracic neoplasia, migrating foreign body or any form of pleuritis? Remember teasing the lungs from the pleura? The pleura is more than capable of inciting a fibrous reaction that will attenuate a vessel.
- Ameroids are only capable of reducing their internal diameter between 36-48% (Hunt, 2014) of their original internal dimension. This means that the ameroid ring relies on fibroplasia around the vessel induced by the casein to finish off the attenuation.
- Using ameroids in the thorax then would logically not work according to the authors, because they surmised that the thoracic cavity had reduced capacity for fibroplasia, yet only 1/7 ameroids placed failed to attenuate the shunt. Therefore, the problem is not with the pleura or thoracic cavity's ability to induce fibroplasia, but with the Marlborough cigarette packaging - and no, other brands will have the same issues.
- Smoking kills, didn't you know?
When we reached out to the authors for comment they agreed that they were uncertain of the constitution of their cigarette wrapping, and based on their results, duly unimpressed with the outcomes.
To remedy the situation, we have supplied the author's institution with some CelloVet for clinical use, and we are looking into establishing a prospective research project in conjuction with them.
So, yet again, cigarette packaging doesn't work, isn't real cellophane, and its use in clinical patients is of questionable value. Be certain it is cellophane - use CelloVet.