Has anyone else also experienced the increase in volume of the pulmonary artery after cannulation in a Langendorff apparatus? So, unlike other Langendorff systems, we only cannulate the aorta, and just puncture the pulmonary artery to decrease pressure build-up in the right ventricle instead of attaching an effluent outlet for it. Could it be pulmonary embolism? But in my case, only the pulmonary artery enlarges, and there is no apparent change in the morphology of the basal outflow trace. I would just like to know how I can avoid this from happening. Thanks!
hello Julius,
I used to work with Langendorff system with retrograde perfusion on rat heart but I cannot understand how the pulmonary artery enlarges, May be it could be better if you send a picture of this problem when happened. I hope to help you.
Hello Dr. Abdelkader!
Thanks for your response! I've attached the photo already. It might appear that it's the aorta that enlarges but as I have previously observed, whenever it happens, the aorta ruptures during enzyme digestion, and it has no change in wall appearance, so I assumed that it was the pulmonary artery. Would you agree that this is the same case as in Figure 1 of this paper on pulmonary embolism? http://physiolgenomics.physiology.org/content/39/1/61
Ok it seems to be the same case as pulmonary embolism showing in Figure 1. This happens when the heparin dose is too low. May be you can adjust in good concentration by checking dilution calculation of heparin.
Wow, this makes much more sense now. We previously thought that we inserted the cannula into the wrong part of the aorta (like between the aortic wall, which is silly to be quite honest). Thank you very much Dr. Abdelkader!
As saw in your image may be the pressure on it more than normal
if you used pulmonary artery the Langendorff model switched to working heart system
Hello, Dr. Shekha!
Thank you for your insight! However, I am sorry but I find it a bit confusing. Well, so far my procedure is concerned, I just puncture the pulmonary aorta with a syringe needle.
I was taught as a graduate student in Mike Rovetto's lab to nick the pulmonary artery just as you are doing to avoid RV pressure buildup. The reason the pulmonary artery frequently increases in volume is due to inadvertently putting the ligature around it when tightening the ligature around the aorta. Perhaps clots in the PA outflow could also cause this problem. Also, pulmonary vein cannulation is used for working heart model.
This is very helpful, Professor Ford! Maybe, I always overlook the PA when I secure the aorta on the cannula, because sometimes, I can only see the side of the heart facing me while attaching the heart onto the cannula. I will take note of this, and thank you very much for your help!
Thank you Dr. Acsai! To be honest, I never realized that until now. I always try to make the aorta as long as possible so that I would have enough distance between the aortic valve and the tip of the cannula. I always try to keep the distance as far as possible. Anyway, this is new information to me. Thank you very much!!!
I agree with Karoly's comment. Looking at the picture, it looks like the enlargement is form the aorta, not the PA. This could be due to the cannula too high, as Karoly mentioned, or simply due to the pressure buildup in the LV, which is common when you do Langendorff perfusion. If you monitor perfusion pressure and see the pressure increases, that's an indication of the pressure buildup in the LV. Depending on your protocol, you can open up the mistral valves by insert a balloon, or a piece of tubing, or simply cut them open. Good luck.
I am sorry for my misleading description, Dr. Wang (and everyone else)! But yes, the enlargement was (and always had been) at the aorta. I did it again yesterday and it happened again because I made it a point that the aorta was long enough to keep a gap between the cannula tip and the aortic valve; and I saw that the PA was just pressed out by the enlarged aorta. Thank you very much for pointing this out!!!
Not a problem. I have seen the same problem at times with the aorta. It is still a good discussion for others that will help in the future. Good luck with your studies.
I would like to know how long it takes for the aorta to become enlarged as on the picture. If it happens relatively early in the perfusion protocol (i.e. soon ater mounting), the most likely problem in my experience is streching of the aorta when mounting. This would also impact on the heart function, so it is to be avoided at all costs. This can happen even if your canula is small enough to easily fit into the aorta. If your hands are not stable during mounting, the aorta is often damaged.
If on the other hand, this happens only late during the perfusion protocol my previous advice would not apply. in such a case, I would start looking at things like pressure build up. In order to aid you in determining things like pressure buildup, coronary flow measurements can be of great value. If fluid is trapped in a compartment in the heart coronary flow is often lower than expected. It can even change during the course of the experiment.
Finally I would like to say that we have often found that if we use thin 100% cotton ropes to hold our hearts in place it causes less damage to the aorta than the more synthetic ropes or sutures which is readily available.
Good luck! I hope you are able to solve this problem soon!
Hello, Mr. Bester! This thread is getting more and more enlightening with every new answer! As a matter of fact, the enlargement of the aorta always happens as soon as I finish mounting the heart onto the cannula; and I will have to admit that I sometimes stretch out the aorta especially when the opening seems too small for the flange to accommodate. I am trying to avoid that now and so far, I haven't experienced it again. I have also applied previous tips by other researchers, and all of it helped greatly. However, I still encounter problems with calcium reintroduction. I am adding increments of 200 uM calcium to a final concentration of 1000 uM but usually, there is cell movement at 400 uM calcium. Maybe a little off topic, but would still greatly appreciate tips and suggestions. Thank you so much!
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