Friday, August 04, 2006

Oh, What a Feeling!

This week offered new experiences. We were finally able to “coil” a patient that had previously been rescheduled due to complications. I am glad that it happened this soon as the patient had an aneurysm measuring 14 x 11 mm. Luckily, there was no hemorrhage or any other complications. The case went very well and the patient is expected to make a full recovery.

Cardiothoracic surgery is amazing. I was afforded the opportunity, along with my colleague, Jan Kostecki, to observe a CABG (coronary artery bypass graft). In this procedure, the patient’s vasculature around the heart was badly compromised. The plan was to endoscopically take veins from this patient’s legs to replace the vasculature of the heart. The process of removing the veins from the legs of the patient has come a long way. In the past, a surgeon excised the vein by scalpel, leaving horrible scars and a substantial would to heal from. This procedure was done with only to small incisions above and below the inside of both knees. It was very exciting to see how technology had changed.

While a doctor was getting the replacement vessels, another surgeon was working to prepare the thoracic cavity. For the procedure, the chest was opened via a scalpel and sternum saw. The appropriate vessels were cauterized to minimize bleeding and the patient was put on the heart and lung bypass machine. Cardiothoracic surgery is unlike neurosurgery where a screen shows you everything that the surgeon is doing. In cardio surgeries, one needs to be very close to see what is going on. Both Jan and I were constantly trying to walking around the room to get the best spot. At some point, one of the nurses told us that we could stand on a step stool behind the patient’s head so that we could have a better perspective. We were cautioned to only stay there momentarily as not to upset the attending surgeon, Dr. Krieger. By the time Dr. Krieger showed up, we were only on the outskirts, making sure not to be in anyone’s way. He saw us looking on and asked who we were. I explained that we were graduate students in BME from the main campus. At that point, he told us to reclaim our prior position near the patient’s head. He began explaining everything. The anesthesiologist had to ask us to move to check on the patient’s vitals. Those moments were very short as Dr. Krieger was intent to explain the finer points of this procedure and the procedure was progressing well. We were blown away by the procedure and his kindness. We learned so much and it was really exciting to see a person’s heart and lungs. Books can’t really capture what my eyes beheld. The heart’s beating was fascinating. Even when cooled with ice, this person heart was so strong that it continued to beat. After finishing the procedure, the person was immediately able to come off of the bypass machine and use his own heart to pump blood to his entire body. It was amazing to see and very fortunate for this patient. The procedure was a success and cardiothoracic surgery is a very cool place to be.

My experience really can’t be described in words. During these 6 weeks, I have tried to capture the highlights but my words pale in comparison to the actual experience. I hope that you all have enjoyed the depictions of my experiences. I hope that in the future I am afforded this opportunity again. Besides, the procedures, I was able to have meaningful dialogue with some physicians about potential collaborations and consulting opportunities after graduation. I am very excited and look forward to the future as I think that it will be a bright one. Also, I have a new appreciation for the hard work that so many put forth to take care of patients and give them the best opportunity for a successful recovery. I am glad to have been a participant in the 2006 Biomedical Engineering Summer Immersion at Weil Medical College of Cornell University.

6th week report and acknowledgements

Last week, I continued the clinical study and research in the vascular surgery area. With the previous 5 weeks' study, everything went very well. I could understand, at least partly understand, almost everything that happened in the ER and OR.
Friday, I attended the last day of clinical practice: observing the patients in the examination room. Actually I found that I have met half of the patients. At 1pm, I told Dr Karwowski that I have to leave. He felt very happy for my six weeks' learning and he even told some patients that I knew more than most of his residents(just joking). Anyway, I really learned a lot during these 6 weeks. From my heart, I appreciate that the BME department could offer such a wonderful course that I would never forget. This course gives the biomedical engineering students the unique chance to receive intensively clinical trainning in the one of the best hospitals in the world. For the international students, at least for me, this may be the 1st chance that they could touch the US hopital system. After 6 weeks' learing, we all have the plentiful experience in the clinical practice area.
Besides the above things, the course would definitely have a postive effect on the students' study, research and future career, though we could see it immediately. By touching the art of world biotechniques applied in the hispital, we have a full undestanding of the development of techniques and we know what should be improved and what are really needed by the doctors.
These invaluable training and experience is just the BME students needed.

The following pricture is for Dr Karwowski and me in the operation room 10(OR 10)


Clinical Mentor: Dr John K. Karwowski ; Course Director: Dr Yi Wang

(NY-Presbyterian Hospital)
Dr K. Craig Kent
Dr Peter L. Faries
Dr Stephanie C Lin
Dr Brian Derubertis
Dr Russell Lam
Dr Soo Rhee

Ms Rachel Gerber
Ms Lisa Chepurko
Ms Monica D. Covington
Mr James Maniglia

Nurses in M014 and OR 10 :
Joyce and Malgorzata melendez

(BME department)

Professor Michael Shuler
Professor William Olbricht
Professor Lawrence Bonassar

Belinda Floyd

Rachel Bowles

Investigation of stent fracture

Investigation of stent fracture and restenosis Part I

In medical area, a stent is either an expandable wire form or perforated tube that is inserted into a natural conduit of the body to prevent or counteract a disease-induced localized flow constriction. The main purpose of a stent is to overcome important decreases in vessel diameter. Although perhaps the most popular use of stents is for the coronary arteries, they are widely used in several other structures, such as peripheral arteries and veins , bile ducts, esophagus, colon , trachea or large bronchi, ureters, and urethra.One of the weak points of vascular stents, however, is the development of a thick smooth muscle tissue inside the lumen, the so-called neointima . Development of a neointima is variable but can at times be so severe as to occlude back the vessel lumen (restenosis ), especially in the case of smaller diameter vessels, which often results in reintervention. Considerable improvements have been made, including the use of more bio-compatible materials, anti-inflammatory drug-eluting stents, resorbable stents, and others. Fortunately, even if stents are eventually covered by neointima, the minimally invasive nature of their deployment makes reintervention possible and usually straightforward.
The follwoing are some stent pictures(more pictures would be shown in the presentation)

Wednesday, August 02, 2006

My HSS project

Hip Implant

For the HSS program, I had to investigate the posible causes of failure of an hip implant, that they gave me. This implant was taking out from one of the patients at HSS, then they replaced it with a different model hip implant and the woman is still walking around the NYC street, actually she lives in Park Ave. !!

I am posting the picture of the implant. When I saw this, I was very curious to find out what happened. You can take a look:

So, I already know after reading the medical records, paper, radiographys and talking with doctors the reason of failure. But I will present the results on the presentation days.

Also, last week I attended to a hip revision surgery and before last week to 2 hip surgeries, this was very useful and interesting for me...


Open vascular surgery II: Bypss surgery

In medicine, a bypass generally means an alternate or additional route for blood flow, which is created in bypass surgery, e.g. coronary artery bypass surgery by moving blood vessels or implanting synthetic tubing. Vessels frequently used for the bypass are large veins taken from the patient's leg. When and where possible, however, an artery is cut from one place and reconnected to another artery, which supplies a region that needs the blood supply more than the original site. Generally the blood flow in the receiving vessel is temporarily interrupted or reduced while the bypass is connected. To create a bypass to a critical artery, the connection can be made while blood is flowing through the receiving vessel with the ELANA operating technique.
Bypss in biomedical engineering:
Artificial blood vessel as bypass
1, vascular graft made from ePTFE
2,engineered blood vessel
For the first one, the current commericial graft could work for more than 20 years, which is pretty successful
For the second one, this area is a new area and it just has been investigated in recent years.

Open vascular surgery I: Amputation surgery

Something about the amputation surgery

Amputation is the removal of a body extremity by trauma or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on individuals as a preventative surgery for such problems. In Islamic countries, amputation of the hands or feet is sometimes used as a form of punishment for criminals. In some cultures and religions, minor amputations or mutilations are considered a ritual accomplishment.
Types of amputation include:

amputation of digits
partial foot amputation (Chopart, Lisfranc)
ankle disarticulation (Syme, Pyrogoff)
below-knee amputation (transtibial)
knee-bearing amputation (knee disarticulation)
above knee amputation (transfemoral)
Van-ness rotation (Foot being turned around and reattached to allow the ankle joint to be used as a knee.)
hip disarticulation

amputation of digits
metacarpal amputation
wrist disarticulation
forearm amputation (transradial)
elbow disarticulation
above-elbow amputation (transhumeral)
shoulder disarticulation and forequarter amputation
The first step is ligating the supplying artery and vein, to prevent hemorrhage. The muscles are transsected, and finally the bone is sawed through with an oscillating saw. Skin and muscle flaps are then transposed over the stump, occasionally with the insertion of elements to attach a prosthesis. In a disarticulation amputation, the bone is removed at the joint.

For vascular surgery, amputation surgery covers the debridement.

What could the biomedical engineer do for the amputation surgery?

1, drug(antibiotics) delivery for anti-infection
2, wound healing drugs orwould healing accelerator

Tuesday, August 01, 2006

5th Week Brings A Change to the Routine

So Monday and Tuesday were the normal routine where I got up early, went in for rounds with the residents on 4 North at 8am, and observed cases till about noon. After that was done, I headed down either to the MRI room or the SPECT room or the CT room and read images with the fellows and attending doctors that were in the room. It has become quite easy to diagnose the common diseases that the doctors see on a regular basis in the hospital and I have become proficient at using the software and manipulating the data/images to make a diagnosis or to show a person that is observing where the problem lies.

During these two days as well, I cleaned up my patient data set that I had already complied and excluded some patients that had complicating factors or that there was not enough data present to make sure that they fit our study. After going through this group and making sure that the patients that we had all fit our criteria, I took the list down to the MRI room to have the data retrieved and placed on the workstation so that I could begin the real data analysis. Suffice to say, retrieving the old records is always put on the back burner, and as I write this blog a week later, I am still waiting for the patient files.

In addition to the work that I had done, on Friday I met up with Dr. Matthew Janik and he showed me the correct way to trace images on the MRI software (the tracings use a complex algorithm that allows for the measurement of size, shape, and functionality of the heart). These tracings are the method in which I am going to obtain the data for our study, but one thing that is blatantly apparent is that the tracings are all subjective to the person that is doing the tracing. Since an MRI image takes a slice of the object, the image has items that are both in and out of the plane, and these items can be either traced or not traced. Therefore, the tracings of the images that we have will be evaluated by three experienced MRI imaging experts and then those opinions will be taken into account for the final values obtained.

Now the fun part of the week begins…well Wednesday and Thursday. So my clinician left for a conference and since I could not do anything related to my project I talked with Julius and asked if I could observe some of the medical procedures that had been going on in his area of expertise. On Wednesday I was able to see an aneurysm get clipped in a 30 year old woman. When we walked into the OR, the woman was already on the table and the fellow had already removed her scalp, pinned it in place, and was beginning to clean up the skull so that there could be access to the brain. At the same time, there was an incision made in the woman’s neck and a clamp was placed on her carotid artery to stop blood flow into the region where the aneurysm was. The first thing that struck me in comparison to the imaging that I had been doing these last few week was the smell of the OR. The smell of tissue being cauterized is something that many people don’t forget, and for those that wonder what its like, I think its like when you singe the hairs on your arms when reaching over a stove or a camp fire. The smell is really that pungent, but you begin to be desensitized to it quite quickly. After that I also realized the amount of instruments and technology that goes into a surgery and how everyone has a specific role to play. Once the skull was cleaned off the surgeon took a tool that looked like a Dremel and went to work cutting out a portion of the skull where the aneurysm was located. After removing the skull and dissecting the way down, the aneurysm was pinpointed on the microscope and tv monitors that were present in the room. The next step was to take small clips (yes, clips like those used to hold laundry on the line) and clip the blood flow to the aneurysm. To make sure that all the blood flow was stopped, both ultrasound was used to see if there was any flow through the area and a fluorescent dye was injected that could be seen under infra red monitors. The clip was in the correct place and then the surgeon popped the vessel and closed up the region. That was an amazing procedure and took about 5 hrs to complete.

The rest of Wednesday and Thursday were spent in the Interventional Radiology room on the 5th floor where I was able to observe catheterization procedures that mapped the blood flow in the brain. These procedures were the same as those as I had seen in the cardiology catheterization room, but the focus was on mapping flow through the brain. One patient that we had seen had a tumor that was detected by CT, but upon looking at the blood flow via that catheterization the decision was not to perform surgery because there was no single vessel feeing the tumor and there was no risk to the patient. The rest of the cases were also uneventful but it was interesting to see how the same procedure could be used to diagnose other conditions in the body.

Another week

This week started with me following around Dr. Te, who does laser surgery. The surgery I watched was to reduce the size of a non-cancerous prostate. If a prostate gets too large it can interfere with urine flow, potentially completely blocking it off. Originally the cure was to cut away the excess tissue electrically, however it was a very bloody surgery. This could lead to complications if the patient lost too much blood. Now the procedure is to use a green laser to vaporize the tissue. A green one is chosen because it is at the maximum absorbance of blood. When tissue is vaporized the blood is the main absorber, causing it to clot. While there was some bleeding, it was never excessive. While the technology of the surgery is quite impressive, it is an absurdly tedius surgery to perform. In the first case I saw it consisted of three hours of moving a fiber optic cable back and forth a fraction of an inch while it destroys tissue.

Also this week I took several students to watch robotic surgeries. They typically are a good surgery to watch, since the view the doctor sees in put onto a large 3D screen. Compared to many surgeries this gives a clearer picture of what the doctor is actually doing...

Friday I was finally able to get the health physics people to come and measure radiation emissions from the display on the robot. Rather unsurprisingly, there was essentially nothing. While they did not have the equipment to measure UV, X ray emissions were too low to measure. These are the biggest risk from CRT displays since high energy electrons being flung into a screen on the display can create them. However usually the glass is enough to block all of them. In this case it was clearly true. There is still some risk of UV light, however glass is also an efficient absorber of UV light, which will reduce the risk.

Also, this monday, I saw the first case that I nearly had to walk out on because of the scale of it. A 23 year old on a motorcycle was driving to work when a garbage truck ahead of him made an abrupt left turn. At a speed of around thirty five miles an hour he crashed into the back of the garbage truck. At the point I saw the patient his face was scratched up(his helmet broke) his arm was shattered, and his leg had been amputated at the knee. The side of his amputated leg had a approximately eight inch, by four inch gash where the muscle had turned black with gangrene. When they took the bandages off the smell was almost worse than the sight. The doctors then proceeded to take off more of his leg. First they cut the skin and muscle off of a five inch section of the bottom of his leg. Then they worked up his leg looking for living tissue. At the point I decided I had seen enough, and would probably be sick if I saw more, they had taken one complete thigh muscle out, and appeared like the rest might have to go. There was talk of removing the entire bone at the hip, although the doctors still hoped that could be avoided.

Monday, July 31, 2006

Evan in Radiology

Dr. Prince examines Evan's MRI. Together they are working on a project that will hopefully improve the breath hold technique used in MRI. Evan was the first subject.

Dr. Prince compares the results between the natural breath hold and when the subject was given oxygen. The results seem to hold potential.

Another image from the first trial.

Robby in the Lab

Like Alecia and Daniel, Robby was assigned a failed implant to study and determine the cause of failure. Robby's implant was from a total hip replacement. He has the patient's files and a series of x-rays to study.

Robby compares the actual explanted hip to the image of the hip in the x-ray. The implant was removed from a 50 year old woman after she had experienced frequent hip dislocations.

Robby examines the liner to determine why it failed and how it undwent wear.

The liner experienced wear after impingement as a result of the higher walls of the constrained liner. The implant lasted just two years.

The femoral head shows signs of metallic wear. It was also replaced.

Ben Hawkins: Week #5

NICU Rounds
Rounds in the NICU this week were pretty much more of the same. It was a good week as several patients went home or to non-intensive care facilities. Some of them have conditions that will be with them for the rest of their lives and some will make full recoveries, but its great when they leave the intensive care unit, because they will have a life ahead of them. Of particular interest:

Patient A
Patient A's condition improved over the course of the week, with the "dry gangrene" not advancing beyond her toes, and the body's auto-amputation taking more and more effect. X-rays showed that none of the infection from the foot spread to her bones (this was a concern due to some distal tibial lucency on one series of X-rays; a skeletal study revealed no osteo-damage). She required increased ventilator support, but she no longer suffers from the chronic lung disease that put her on mechanical ventilation in the first place.

Patient B
Patient B is going home this week. His condition is not such that he requires intensive care anylonger. His multiple infections led to eye surgery (bilateral lensectomy), but the optometrist's prognosis was that with contacts his visual acuity would allow him at least to distinguish shapes and would likely permit him the ability to read.

Patient C
Patient C was diagnosed with diastomatomyelia (a malformed vertebra causing spinal nervous tissue to grow exterior to the spinal column, similar to spina bifida, and this tissue bifurcates around a protrusion of the malformed vertebra, forming a mouth-shaped opening in the tissue). Other than this condition the patient was treated for minor conditions. Neurology would not operate on the patient due to his age, and so he will be sent home this week. The parents were told to look for changes in the strength of his lower extremities, and come for a re-evaluation in 6-12 months.

Other patients
Other cases of interest include a patient who was supposed to receive a circumcision. Fortunately there was some continuity of care and he did not receive one because of his hemophilia...

Another patient presented last week with several defects which suggested a possible genetic defect in the "Sonic hedgehog homologue" protein; one of three proteins in the hedgehog signaling pathway. Originally found in fruit flys, three homologues were found in mammals, the desert, Indian, and Sonic hedgehog genes, so-called because a loss of function defect phenotype of the hedgehog protein causes the appearance of spines on the body of the fruit fly. In mammals, the hedgehog pathway affects morphogenesis, specifically in limbs and midline structures. The patient had his heart on the right side of his chest, but not axially mirrored, as is often the case. In addition, he had diaphragmatic eventration, or a loss or weakening of the diaphragm. This condition caused him to lose lung volume as his stomach expanded after eating, causing compression of the lungs, a loss of tidal volume on inspiration, leading to apparent problems with respiration. With the caveat that close observation was necessary after feeding, this patient will be released this week. Much of the information on this topic was taken from: Wikipedia.

Sunday, July 30, 2006

Vishal's Fifth Week

Coronary Artery Plaque Composition Identified by Multidetector Computed Tomography Predicts Stress-Induced Myocardial Ischemia

In the fourth week, I identified 121 patients who had both received computed tomography (specifically multidetector computed tomography, MDCT) scans, and had undergone nuclear stress testing (myocardial perfusion single photon emission computed tomography, MPS). I will give a more detailed description of these techniques in subsections below. Last week, I also entered the MDCT data for those patients into an online database. We also sent the list of patients to the nuclear stress test labs, and they prepared the stress test data for us.

This week, Dr. Min and I combined the MDCT and the MPS data to see if we could find a relationship between coronary plaque type and stress induced ischemia (reduced blood flow). We quantified ischemia by using a standard American Society of Nuclear Cardiology 17-segment model. Each segment was scored by two experienced cardiologists on a scale of 0-5, ranging from no reduction to severe reduction of radioisotope uptake. We found that the frequency and extent of ischemic MPS results were significantly higher in individuals exhibiting higher levels of mixed plaque. Conversely, individuals with higher amounts of soft plaque or calcified plaque did not have higher rates of ischemic MPS. We plan to submit this study for publication, so I will not post the data here.

There are several additional interesting studies we can perform with essentially the same data set. Our next goal is to determine whether we can predict wall motion abnormalities from MDCT images. This requires that we gather the raw image data from optical discs, and reread the images. I spent the rest of the week finding the image data on the discs, and burning them onto conventional CDs so that we can read them at leisure. I should be able to collect the last of that data on Monday. Wall motion abnormalities show up as dark spots on MDCT images. We will make predictions about the wall motion abnormalities using MDCT images, and then compare those results to the nuclear stress test conclusions.

Multidetector Computed Tomography
Detailed lectures on MDCT principles can be found at:

In conventional CT, the patient is placed between an x-ray source and a detector. The source and detector are rotated around the patient, collecting the x-ray attenuation data from many different angles. This data can then be used to reconstruct an image (see, for instance: Multislice detectors incorporate several rows of sources and detectors, which can drastically reduce both the scan time and the radiation dose to the patient. Future generations of MDCT machines will likely reduce the radiation dose to that of a conventional chest x-ray or less.

Myocardial Perfusion Single Photon Emission Computed Tomography (MPS)
In MPS, a 20- to 30-mCi dose of a radioisotope, technetium-99m in our case, is injected into the patient. A gamma camera is then rotated around the patient collecting 2D images, which can be reconstructed into the 3D distribution of the radioisotope using the same methods as in MDCT. Since these images can be gated, quantitative information about wall motion, left ventricular ejection fraction, wall thickness, and cardiac output can be obtained through MPS.

Are We There Yet?

Most of this week was spent trying to define the parameters of my project. I am very lucky to be shadowing Dr. Riina as he is a very busy surgeon. However, that also means that there is less time for defining project parameters and such. However, at this stage my project proposal looks as such.

Before any procedure or operation, most patients desire to know their chances of a successful outcome. In many situations, patients will not move forward with the proposed procedure if their chances are not favorable. Obviously, no doctor keeps track of every single case so it is very hard to calculate any success rate associated with any given procedure. Even more confounding are the different variables associated with each case. Ultimately, a physician’s attempt to give accurate prognostic information is a calculated guess. One can be certain that by no means does a physician intentionally mislead a patient as they are not computers and certainly not omnipotent. What if it was possible to devise a scale with predictive values based on a physician’s body of work? This prognostic indicator would be semi-quantitative and give a more accurate assessment of the patient’s chance of having a successful procedure. It is proposed that the scale would consider and account for the multiple variables effecting patient’s with an aneurysm such as location, size, age of patient. The value generated would then correlate to percentage ranges to be determined. For this type of study, a sample of historical data would be taken from multiple cases. After analysis, this information would be used to incorporate the multiple variables existing in aneurysm cases to be used as tool to give patients a truer assessment of their relative chances of a successful procedure.

This week was slow. Dr. Riina was in the hospital for two days so on the off days, I observed Dr. Pierre Gobin, a neurology interventional radiologist. He performs many of the same procedures as Dr. Riina. I saw an interesting case where this child had a retinoblastoma. To treat this, Dr. Gobin embolized the tumor by stopping its supply of blood with polyvinyl alcohol particles. At this stage, it is a possibility that the tumor will be carefully excised by surgeons at Memorial Sloan Kettering Cancer Center.

I also had a chance to get back to the OR. I saw another aneurysm clipping. This was much like others I have described but they never get old. A couple of the really cool things about this particular procedure were the location of the aneurysm and the clipping of the lower vessel that fed into the aneurysm. The aneurysm was located near the optic nerve. Because of the complexity of the area, a temporary clip was placed on the external carotid artery to stop blood flow to the aneurysm. At this point, Dr. Riina proceeded to clip the aneurysm. For this case, two clips measuring more than 10 mm each were used. One was initially in place but was not sufficient to stop blood flow to the aneurysm. This was because of the location and neck size of the aneurysm. After both clips were in place, Dr. Riina used infrared imaging and a Doppler instrument to check the blood flow integrity and assure that the abnormal vessel was properly repaired.

Well, the last week of this immersion is approaching quickly. I am looking forward to making more progress on my project. I will be collecting the much needed patient data to get the study underway. After receiving the patient data, the meat of the project will begin as I need to investigate if a correlation exists between a successful procedure and any variable or variables associated with each patient’s particular procedure. If all works well, a recipe may exist for each patient to have a successful procedure. Maybe as important, this study could offer semi-quantitative prognostic information for Dr. Riina’s patients in the future.