Friday, August 20, 2010

Week 5

On Monday I was able to observe the final stage of a procedure in which an inferior vena cave (IVC) filter had to be removed from a woman who had undergone surgery for a tumor in her abdomen a few months back. After the tumor had been removed in the initial surgery, chemotherapy had been placed into the abdominal cavity and allowed to rest for a period of time before being removed. This caused the internal organs (esp. the intestines) to have a great deal of scar tissue that essentially fused them together and to the wall of the abdomen. At the time of the initial surgery, and IVC filter had been added as a preventative measure to ensure there would not be problems resulting from potential clots forming after the operation. Unfortunately, and for reasons that are not entirely clear, the IVC filter rotated 90 degrees. The hook at the top of the filter (see image), which is usually used for placement and retrieval, was imbedded in the wall of the vena cava, dangerously close to the illeal conduit. Normally, retrieving the filter in this case would require open abdominal surgery in which the intestines would be pushed to one side so the vena cava could be reached. However, when Dr. Bush and his team make the initial incision, they discovered the sever scaring that had resulted from the chemotherapy agents. This greatly complicated the procedure, but after approximately 6 hours of painstakingly separating the scared intestines, the IVC was reached and the filter was successfully removed.

No one will ever know why the filter rotated just a few months after being put in place. It is possible that force was applied to the IVC at some time during the initial procedure and caused the filter to move. These filters are designed to stay in place and not rotate, so, under normal conditions, they are stable for an extended period of time.

Later, I was able to observe a carotid endarterectomy. In this procedure, an incision is made in the side of the neck, revealing the carotid artery. (Interestingly, Dr. Bush has a unique approach in which he follows the Langer lines, or lines of least tension, along the skin in order to avoid scaring.) Once the location of the plaque is located by palpating the artery, a longitudinal incision is made so the plaque causing the stenosis can be removed. An ultrasound probe is often used in diagnosing carotid artery stenosis, and a similar probe is used after the artery has been closed in order to ensure proper blood flow has returned. Endarterectomy is commonly performed when the artery is narrowed by more than 70%, however each physician seems to have a slightly different threshold when considering patients of advanced age or patients with other medical conditions. It was very interesting to see what the plaque looked like and how ridged it was. Part of the plaque was sent to pathology (as is anything removed from the body), but the remaining portion was slated to go to a researcher at Colombia who is investigating a potential link between bacteria and plaque formation. This is a rather "off the wall" hypothesis in modern medical research, but he claims to have had some promising preliminary results. It will be interesting to see if they are reproducible.

The remainder of the week was dedicated to working on the bioreactor project. Mice were identified for use in the project, then materials were obtained and tested using part of a glove as a pseudo-lung for a dry run. The appropriate growth media (which costs about $1/mL) was identified and obtained. The final version of the system was set up on Friday, and after a 12-14 hour day in the lab, the fully assembled system was knocked over as a final set of photographs were being taken - just moments before it was to be transferred to the incubator. The process began again on Saturday, and with a successful transfer to the incubator, the tissue was left to run for 45 hours.

On Thursday we had NMR training. Having never worked with an NMR before, I found the manual "How to Learn MRI - An Illustrated Workbook" (written by students and Dr. Prince) to be extremely helpful. After reading the lessons for the week, the hands-on course was easy to understand, and everyone seemed to have fun operating the MRI. After working with a phantom for some time, one student volunteered to have their knee scanned. The images were clear, and the scan seems to have been a successful first attempt on the part of the students in the course.

Note: The above image is from