Monday, June 28, 2010

Week 2 - Bailey Cooper

Monday morning began with a bypass scheduled for a 69 year old male suffering from an aneurysm near his left knee. An angiograph was used to image the flow of blood through the aneurysm and to pin point the section of the femoral artery that needed to be bypassed. Since a first attempt, with the catheter placed just above the aneurysm, only provided images of the upper portion of the affected area, the catheter had to be guided into the aneurysm in order to allow the dye to progress further down the artery in order to obtain an image of the end of the affected area. After a clear image of the femoral artery was obtained, the surgical team began isolating a superficial vein from the patient's leg in hopes of grafting it to the artery instead of using a synthetic material. Unfortunately, after hours of painstakingly isolating the vein and securing all of the branches originating from it, the team found that it was not healthy enough to use, and a PTFE (a.k.a. Gore-Tex) graft had to be used instead.

The vein had been affected by thrombophlebitis (vascular inflammation resulting from blood clots), and after removing an occluded portion from the middle, there was still a ridge of scar tissue within the vein that could not be removed while maintaining the necessary length. From an engineering perspective, the PTFE graft was quite interesting since it contained a membrane that allowed it to leak like a sieve when flushed with water but prevented blood from leaving the tube. The PTFE graft was further designed to promote the growth of endothelial cells along its interior lining and coated with heparin to prevent blood clots from forming along the inner surface post-op. (The patient was already on Coumadin due to an angioplasty on this right leg one week prior, so clotting inside the graft was not expected to be an issue.)

Since this was a large artery, the PTFE graft was suitable, but blood clotting issues still prevent PTFE from being effective when bypassing smaller arteries. A new nanocomposite material developed at University College of London aims to solve this problem, and it is scheduled to enter clinical trials later this year. The new material is based on Silsesquioxane and has shown remarkable properties in the earlier tests (prevention of the coagulation cascade, etc.), so I will be interested to see how the clinical studies go.

I was surprised that over an hour of sewing was required in order to secure each of the graft to the artery and to over-sew the corresponding end of the artery containing the aneurism. This has led me to contemplate other materials that could be used to attach the graft to the artery more quickly while providing a reliable seal. I was in the OR for 10 hours, but the surgical team was easily there for over 12 hours. Anything that could be done to save time on such a procedure while reducing the risk of leaks would certainly be welcome.

On a lighter note, I would like to find a way to prevent back pressure from building up when the surgeons are irrigating the graft so those in the OR do not risk being sprayed by the fluid. Oh well, at least I now know how to respond when I am hit with fluids in the middle of an operation. The surgery was a success, and patient has been recovering nicely so far.

During my time in the clinic, I was able to meet many patients and observe a variety of cases, but the one that stood out most in mind was the case of a middle aged man who was no longer able to walk after the successful removal of a malignant tumor 6 weeks ago at Sloan-Kettering left him with a painful blood clot that will now be difficult to treat. It is unclear if his body will be able to resolve the clot on its own or will require surgery, and it is unclear what level of activity the patient will eventually be able to resume. A few weeks ago this man was surfing, running, and generally leading a very active life. Now he is unable to lower his legs without swelling or walk without pain. Ideally, the clot would have been treated 6 weeks ago when it was fresh, but at this point the clot fairly old, so the method of treatment will be different. Further information from the patient's hematologist will need to be considered when deciding the most appropriate course of action. I plan to learn more about the treatment options once the results of his blood work come back.

During a conversation on research, Dr. Bush mentioned a physician-scientist whose work is of great interest to me, and whom Dr. Bush suggested I contact. After a few rounds of e-mails and a forwarding a CV, I was fortunate to be able to meet and discuss my research interests with the PI (who is an investigator with the Howard Hughes Medical Institute and a professor with the Weill Medical College of Cornell University) as well as one of leading researchers in the lab. (Over 15 members of the lab have and MD and/or PhD.) They drew my attention to several recent publications connected to my dissertation topic and offered their perspective on the direction in which the field is progressing - with suggestions on potential modifications to my research. All of this was incredibly helpful, and I eagerly look forward to learning more during my 4 week stent in their lab. We are in the process of establishing a collaboration between their lab and the lab of my mentor, Dr. Putnam. Dr. Bush is also keen to collaborate with them, so this could provide a very nice opportunity to start multiple inter- and intra-campus projects.

The upcoming week holds a couple of key lectures, an opportunity to learn more about a number of projects (both in vivo and in vitro) in the lab, and of course, more time for clinical and surgical observation. There is never a dull moment here, and I am looking forward to what next week has in store.

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