Wednesday, August 09, 2006

I left early to present my work at a conference, so I haven't described my last week at the hospital nor properly acknowledged the help of the clinicians I worked with. I worked on two research projects and observed surgery for a total hip revision.
The first project I presented a case study on a failed shoulder implant to the biomechanics research group. I looked at the records and radiographs and the removed implant to see what happened. The glenoid socket replacement had worn out, causing the person pain so that she had to get it replaced last year. Shoulder replacements do not last as long as hip or knee replacements and they are much less common. When joint replacements wear, the particles cause an osteolytic response in the immune system that tries to digest the metal or plastic particles, and the surrounding bone. This makes a revision difficult to put in, especially in the shoulder where so little bone exists.
During the hip revision surgery, the attending surgeon showed us the damaged bone affected by osteolysis. It had the consistency of gritty toothpaste. In the surgery the cavity was repacked with synthetic bone replacement.
The other project I worked on was for an in-vivo study of wrist motion to establish a better plane of motion for functional evaluation than the current flexion-extension and radial-ulnar. I worked with a physical therapist to craft a model with thermoplastic used in standard wrist splints but with make-shift hinges to allow the wrist to be positioned in a variety of angles. Then I created a CAD drawing of the same so they can get a machinist to make a working model for their experiments.
A huge thank you goes to Dr Sherry Backus of the Motion Analysis lab for facilitating my stay at Hospital for Special Surgery and helping with the implant project. To Dr Wolfe, hand surgeon, who let me observe a surgery of his and included me in the other research project. Aviva Wolfe and others in Hand Therapy who let me watch their work that also has a lot to do with engineering proper bracing and loadings. Others at the Motion Analysis, Brian, Dr Hillstrom, Corinne... Thanks to Biomechanical engineering, especially Dr Maher who arranged so many visits to the OR and Dr Wright who handled the implant study. Thanks also to BME and Dr Wang for hosting such a great program.

Tuesday, August 08, 2006

More EP

It hasn't been even 24 hours and here I am posting again on the week after the BME immersion term technically ended. Somebody stop me! No, but seriously, since I started later than everyone else I owe it to the program and everyone involved to continue this week in the same way as I have been the previous 5 weeks. While everyone is posting their final post wrapping up the immersion, I'm here to make it last that-much-longer. This time I want to share a few thoughts that I have after being in an several operating rooms.

I hadn't been inside on operating ever before this immersion program. But there were a few things that I noticed almost immediately about how one is run most effectively. The first thing that was readily apparent was the chain of command in the operating room. Well, maybe not so much chain of command as knowledge of ones position and duty. That is to say that everyone in the operating room not only knew exactly what he/she was expected to do, but that he/she also knew what everyone else in the room was expected to do. The top man (or woman) is obviously the attending clinician. This is the person with all the years of school, all the years of training, and all the years of practical experience. From what I saw, whatever this person says is final. That is not to say that they may not ask others in the room for an opinion or suggestion. It is true that most times the attending will ask questions as a way to quiz the other fellows or residents in the room. But there were sometimes that I witnessed when a fellow's or resident's thoughts were actually acknowledged and considered in a operating room scenario. But for all intents and purposes, the attending was always right, and everyone there acted as his/her assistance. Which brings me to the fellow/resident. I've heard the both terminologies for what I consider as the same position, so let me elaborate. This is the person who is only a few years away from being an attending themselves. To make life easier I will call this the 3rd or 4th year fellow. Their main goal is to learn as much as possible by both closely observing all and actually performing some the procedures. Comparing the 3rd and 4th year fellow, you have another interesting dynamic. Because the 4th year fellow has had one more year of experience, they are often required to act as teacher to the 3rd year fellow while at the same time being student to the attending. This is important to the 4th year because it further solidifies his/her knowledge of the subject matter and it is important to the 3rd year because every chance to learn is beneficial. The nurses in the room play an invaluable role in making sure everything runs smoothly in perfect harmony. Previous records, patient comfort, operating room sterility and medical tool retrieval are just a few of their many tasks. The attending and/or fellow constantly rely on these people to keep the operation moving forward. The technician is responsible for all the computers/software/hardware in the room. As technology becomes more and more advanced, more sensors and digital recorders and high powered imaging devices are finding their way into the operating room. A malfunction of any could create major problems and its their job to make sure all of the technology cooperates. The anesthesiologist is in every operating room as well and their job is extremely important to everyone as well because no one wants a patent waking up in the middle of open heart surgery! All in all a smooth operating room is quite a marvel to witness as each piece of the puzzle fits in perfectly to create a masterpiece. (that is the cheeziest line in the whole blog I promise) Another thing to highlight specifically is everyones ability to mutli-task. Just because the jobs are relatively well defined in an OR room, that doesn't mean that everyone has one or two things they are expected to do.

On another note, I want to express my desire to see operating rooms go completely digital. Maybe its because I'm an engineer, but I really think that in an operating room there not need be one piece of paper. What I mean by this is that everything should be digitized and on some sort of computer. This would make the creating, retrieval, and transfer of data along with all other forms of documentations much more easy to manage. This would save time and everyone knows that time is money. I'm sure it would take boat-loads of money to revamp all operating rooms in the U.S., but I fee like the 6th best hospital in the nation should be a little more 'wired' than it is now.

Vishal's Sixth Week: Acknowledgements and Thanks

I spent my final week at Weill helping Dr. Min finalize and revise our study on plaque type (as measured by MDCT) as a predictor of ischemia (as measured by MPS a.k.a nuclear stress testing). Several physicians have been tremendously generous with their time and were incredibly helpful in different ways. I would like to acknowledge their help here.

Cardiac Catheterization Labs
Dr. Shing-Chiu Wong: Dr. Wong was my 'official' mentor. He allowed me to observe several diagnostic angiography and stent insertion operations, and taught me a lot about cardiac anatomy and function.

Dr. Morin: Dr. Morin is a fellow who works with Dr. Wong. He was an excellent teacher, and also helped me learn a lot about cardiac anatomy

Dr. Robert Minutello: I also observed some surgeries performed by Dr. Minutello, and at one point considered working on a project with him exploring the correlation between stent size and stent fracture.

Interventional Radiology - Cardiovascular
Dr. Priscilla Winchester: Dr. Winchester invited me to observe procedures in interventional radiology, and was instrumental in helping me find a project to work on. She was extremely helpful, and introduced me to several other doctors in an attempt to find work for me.

Dr. David Trost: I also considered working on a project with Dr. Trost, involving a correlation between stent size and patient return visits.

Tim Levi: Tim is a senior medical student spending time in interventional radiology. He was very helpful in explaining some of the procedures.

Division of Cardiology
Dr. Jonathan Weinsaft: Dr. Winchester arranged a meeting for me with Dr. Weinsaft, who happens to be Jan's mentor. He spent some time looking for a project for me, and ultimately helped me find Dr. Min. He also demonstrated the reading of CT images, and explained some of the advantages and disadvantages of CT vs. MR.

Dr. James K. Min: Dr. Min was effectively my mentor for the last 3 weeks. We worked effectively together, and accomplished a lot in those 3 weeks (see other blog entries for details). Working on this project has been a pleasure, and I am grateful for the opportunity.

Dr. Fay Lin: Dr. Lin is a fellow working with Dr. Min. Without her, we wouldn't have had the data necessary to complete our study.

Dr. Todd Pullowitz: Dr. Pullowitz was visiting for a short time to learn how to read CT scans. He was always in the reading room, and always ready to explain the scans.

Dr. Matthew Cham: Dr. Cham is responsible for the evaluation of the lungs in the CT scans. He was also very friendly and helpful.

Finally, I would like to thank the BME department for giving us this opportunity, Rachel Bowles for her help in organizing activities, and Dr. Yi Wang for coordinating the program.

My Farewell

Well, now its time to say, “Farewell.” Overall, I have had an awesome, unforgettable experience. I would like to thank God for giving me everything that He has to sustain me thus far. This is only possible because of you. I would like to thank Dr. Howard Riina in Neurological Surgery. Dr. Riina, you made this an enjoyable experience. You taught and showed me a great deal in these 6 weeks. Because of it, I have a new appreciation for medicine, especially neurosurgery. Next in line is Dr. Kyle Chapple, a Neurological Surgery fellow. I would like to thank you for my interaction with you and your honesty. You also taught me volumes of information and gave me valuable perspective from that of a resident and fellow. Beyond that, you made the experience fun and enjoyable. To the staff in the Neurological Surgery office and in Interventional Neuroradiology, my hat is off to you all. I felt very comfortable with you all and thank you for your time and insight given to me during the procedures. I would like to also thank the Biomedical Engineering Department of Cornell University and all pertinent faculty and staff that made the 2006 Summer Immersion possible. Lastly but not least, I would like to thank my beautiful wife, Dr. LaShanda T. J. Korley, and my unborn child due August 31. You could have objected but you supported me throughout. I can’t wait to see you. To Baby Clara, I am glad that you waited on your dear old dad. We talked several times about you waiting to arrive after the program in NYC was finished. You are listening well at any early age and I truly appreciate it.

Monday, August 07, 2006

Acknowledgments and Thank You

I would like to acknowledge the following people who helped make my experience at the Cornell Medical School and NYPH one that I will never forget:

Dr. Jonathan W. Weinsaft
Dr. Matthew Janik
Dr. Matthew D. Cham
Dr. Howard Riina (for allowing me to observe neurosurgery)
Dr. Karl Krieger (for letting Julius and I observe the CABG)
Dr. Jorge R. Kizer (for being a test subject for your THICK study)
Nurse Lily S. Yee (for explaining the echocardiogram I received for the THICK study)

Thank you to all the nurses and residents in 4 North for answering all my questions; to the technicians in the MRI, CT, SPECT (aka nuclear medicine), Echocardiogram, Interventional Radiology (neurology), and Catheterization (cardiology).

Thank you to my fellow colleagues in the program: Julius for allowing me to see how that aneurysm was clipped along with our adventures throughout the city, Rachel for being able to organize all the events and outings, Christine and Flor for the games of pool, Vishal and Ben for the card and domino games, Jun and Jesse for heading out to grab wings and beer, Evan and Alex for the best locations in the Wholesale district, Robbie and Daniel for your experiences in HSS, and to everyone who related their stories and projects during our meetings and experiences.

A big thank you to Dr. Yi Wang for organizing this opportunity to experience the medical field and also to Belinda Floyd for taking care of all the paperwork, all the arrangements, and accommodations (this would not have worked out if it were not for you!).

Thank you once again to everyone. This experience will not be forgotten.

extra extra EP

So officially the immersion term is over (tear), but since I started a little later then everyone else I will continue to do clinical related work this entire week. Since my last update, I have spent most of my time on the clinical related project that we all have to do. In my project, I am investigating the properties of atrial electrograms in the heart. An example of an electrogram that we recorded is below.

This electrogram was recorded while this person was in atrial fibrillation. A normal recording (I didn't record one) would have a much longer cycle length on the order of one beat per second. This is an example of 'organized' fibrillation. An example of 'complex' fibrillation is below.

This data is from the same patient but in a different position of the atria. I use the terms 'complex' and 'organized' loosely. This is because presently the only way to determine the difference between the two is by qualitative investigation only. 'Complex' atrial fibrillation electrograms are usually described of electrical activity with a 'relatively short cycle length and heterogeneous temporal and spatial distribution in humans' Nademanee et. al.

Before I get to far ahead of myself, let me remind you what AF actually is. This is a scenario when the electrical propagation throughout the atrium is not as it should be but rather is an erratic motion of activity that circles and criss-crosses causing the heart muscle to sporadically 'fibrillate.' The heart will not be pumped in the most efficient manner. I described some of the methods of ablation that fix this problem in my last post. Some clinicians think that these points in the heart that give rise to 'complex' signals could in fact be the primary rotors and pivot points of the atrial fibriallation wave fronts. Maybe a more direct way of saying that is - get rid of the pivot points (via ablation) and get rid of the fibrillation. The only problem is that there is no quantitative way of measuring just what 'complex' means. Thats where I come in. Currently, I am trying several different signal measurement techniques which aim at describing the complex behavior of a particular signal. First was the simple FFT algorithm and I took a look at the basic sinusoidal components of the signal. I also am in the process of using detrended fluctuation analysis (basically a fancy way of doing a root mean square analysis of a random walk) and approximate entropy (gives a value based on the inherent self similarity of the signal). But I don't want to ruin the surprise so you'll have to wait a little longer before you see those results!

Week Six and Its Over

Its amazing to see how fast six weeks in NYC can fly by…it seems that it was only a few days ago that we had arrived at the medical school and were trying to figure out way about the hospital and now we’re all packing up and getting ready to head back home to Ithaca with the research that awaits our return.

This week began in the OR where Julius and I were able to observe a double bypass open heart surgery, otherwise known as a CABG (coronary artery bypass graft). The patient was a 72 year male that needed this surgery to regain circulation in other parts of his heart due to occlusions in the main arteries that supplied blood. The patient was put under anesthesia and was prepped for the operation with a cardiothoracic fellow working on opening up the chest cavity and another surgeon that was harvesting two vessels from the patient’s legs. The surgeon performing the vessel harvest made two incisions on the leg and arthroscopically inserted a tool that had a fiber optic camera, a pair of cauterizing scissors, and hook that allowed the surgeon to capture and isolate the vessel of interest. It was amazing to see the speed and accuracy that the surgeon worked at and in a matter of minutes had isolated the vessel, cut off all the branching arteries from it, and had it outside of the patient and was cleaning the vessel up. During the clean up process, the surgeon attaches little staples to where the cauterized branching vessels were (for this reason during an angiogram the staples appear on the x-ray) and then attaches the vessel to a syringe filled with saline and pressurizes the vessel to determine if there are any leaks. Once the vessel is cleaned up, its placed in a holding container with saline and then the surgeon proceeds to work on the other leg and to retrieve another vessel.

During this same time, the cardiothoracic fellow has been working on the patient’s chest cavity and has cracked the rib cage (actually sawed through the sternum with a power saw and then opened it up with a chest cavity spreader). He then proceeded to cauterize all the blood vessels that he had cut through and began to remove the pericardium that covers the heart. As soon as he had the heart uncovered, he then proceeded to get ready for the bypass which involved inserting hoses into the chest cavity and hooking the heart up to a heart and lung machine. This was an amazing sight to see the amount of blood and saline that is used during the recirculation process and the color and thickness that blood takes on when it is flowing in such volumes. After the patient was hooked up to the machine, the heart was chilled to 10C and the chief surgeon Dr. Krieger came into the OR. Even at 10C, the patients heart was strong enough to keep beating and the surgeons then set on with the second part of the procedure which was identifying where the new vessels were going to be grafted on to the heart. During this time, Julius and I took turns to stand by the anesthesiologists station and look down onto the heart and what was going on. After the back vessels had been attached to the patients heart, Dr. Krieger looked up and asked what we were doing in the hospital, our reply was that we were graduate students in the Immersion program and we were observing. He replied, “Observing? You’re not observing. Get up here and see what we’re doing.” Now this was an amazing treat, we were able to stand again right by the anesthesiologists station and look down on the front part of the heart as it continued to beat. During this part of the procedure the surgeons took the aorta and clamped it, and then punched holes into it to attach the vessel grafts that were sewn onto the punched holes. While this was going on, Dr. Krieger was talking to us and describing the whole procedure in all its details. The patient was taken off the heart and lung machine afterwards without needing his heart restarted because it had continued to beat during the whole procedure and no bleeding was evident. The fellow then closed up the patients chest and the procedure was over in under 6 hrs. To say the least, that procedure was just amazing.

The rest of the week was spent trying to got old MRI records of patients restored on the workstation so that I could begin tracings for my project with Dr. Weinsaft, but that did not happen till Wednesday. I managed to complete a few tracings before I left, but ended up having to leave the rest of the project for Dr. Janik (a fellow scientist who had been working with Dr. Weinsaft on a previous collaboration). In addition to working on the project, I was able to sit in on a few more MRI/CT readings and go in for a few more morning rounds with the residents on 4 North.

Wednesday evening we had our wrap up meeting with Dr. Yi Wang and had a great meal at an excellent sushi place (except for the air conditioning breaking down), while on Friday it was one last trip to the 55th Street MRI building to see a few more readings, followed by a quick lunch with Dr. Weinsaft, and then last minute packing and laundry before the bus left back to Ithaca.

Overall I must say that the experience this summer was an amazing one. Getting to work at the medical hospital allows us engineers to see how the medical system works, how the doctor and patient interactions occur, how current techniques are used to treat and diagnose disease, and how we can use our own skills to help improve specific problems that currently exist in the medical field. This opportunity that is afforded by Cornell should be extended and modeled at other schools that have a Biomedical program because through these programs, the students really begin to see what the fields really need in terms of devices and new inventions that can bridge the biological and engineering gaps that exist.

Projects, Projects, Projects

It's almost the final week in NYC and I have been busy seeing my last few surgeries and working on my projects. I essentially have two projects including a case study on a retreived constrained acetabular liner and femoral head and the segmentation of the Intervertebral Disc from MRI images. The implant was retrieved from a 50 year old patient with a medical history of lupus and connective tissue disorder. The patient had received a THR which suffered from recurrent hip dislocations. It was decided that due to weak connective tissue the patient would most likely benifit from a constrained acetabular liner.

A constrained acetabular liner has an increased wall liner as well as a constraining component that locks the femoral head into the acetabular compartment. This device has the advantage of preventing the femoral head from slipping out of the acetabular shell and dislocating. There are disadvantages to the acetabular liner. The increased height of the wall liner tends to lead to impingement of the femoral kneck on the liner increasing the tendency of a lever action to create anterior dislocations. In addition, the constrained liners tend to have thin polyethylene and reduce the range of motion of the patient. The impingement of the femoral kneck and the liner can also lead to increased wear and osteolysis of the implant. As a result, these implants are usually considered "last resort" devices.

This patients device was inserted and worked well for two years until it encountered a hip dislocation, and the constrained acetabular component and femoral head were removed and replaced. Severe impingement was discovered on the acetabular liner and was said to be malalligned by the surgeons removing the component, which is consistent with the sever impengment. However, it was not said in what way the cup was malaligned. The radiographs show proper placement of the acetabular shell and femoral head however the placement of the acetbular liner can not be determined from the x rays. It was determined that the malalingment led to the impingement of the wall which led to the dislocation of the femoral head. Impingment was also noted on the posterior of the acetabular shell and metalic markings were noted on the femoral head. It is likely that the markings occured during the dislocation of the head with contact between the femoral head and the acetabular shell. Severe osteolysis was not noted as the femoral stem and the acetabular shell were firmly in place. The case was extremely challanging with my limited background with hip implants but this provided an opportunity to really learn something new as I investigated the case.

In addition to the case study, I was able to observe a total hip revision and see the replacement of an acetabular liner. Dr. Padget took time out to discuss the femoral head component that was removed and the problem of the phase change of the zirconium femoral head from tetragonal to monoclinic that results in the failure of the implant. The femoral head that was removed in my case study will be analyzed for this phase transition as well.